Mechanical knowledge

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1: What are the main forms of metal structures? answer: There are frame structures, container structures, box structures, and general component structures. 2: How many parts can the riveting operation be divided into according to the nature of the process? answer: It is divided into material preparation, setting out, processing and forming, and assembly and connection. 3: What are the methods of connecting metal structures? answer: There are riveting, welding, mixed riveting and welding connections, and bolted connections. 4: In the machinery manufacturing industry, riveters belong to the (thermal processing category). 5: What is thermal processing? answer: The metal material is fully or partially heated and processed into shape. 6: What is the main structure of the truss structure? answer: It is based on profiles. 7: What is the main structure of the container structure? answer: It is mainly made of plates. 8: The box structure and general structure are structures made of a mixture of (plates) and (profiles). 9: Material preparation refers to the preparation of (raw materials) and (part blanks). 10: Steel plates and profiles may be deformed during transportation, hoisting, and storage. 11: The deformation of steel will affect the normal progress of parts (lifting, blanking, gas cutting) and other processes. 12: If the deformation of the parts during processing is not corrected, it will affect the structure (correct assembly) 1 13: The deformation caused by welding will reduce the (accuracy) of the assembly, generate additional stress inside the steel structure, and affect the (strength of the component). 14: The deformations of flat steel include (bending, twisting, and combined bending and torsion deformation). 15: What types of multi-roller straightening machines can be divided into based on the arrangement of the shaft rollers and the position of the adjusting rollers? answer: It can be divided into upper and lower roller row parallel straightening machines and upper and lower roller tilt straightening machines. 16: What are the heating methods for flame correction? answer: There are points, lines and triangles for heating. 17: What factors determine the effect of flame correction? answer: Determined by the heating location and heating temperature. 18: What are the correction methods? answer: Mechanical correction, manual correction, flame correction, and high-frequency thermal correction. 19: What is the first step in making a metal structure? answer: Lofting and numbering are the first steps in making a metal structure. 20: What impact does staking and numbering have on the product? answer: It will directly affect product quality, production cycle and cost. 21: What are the commonly used quantities for lofting? answer: There are wooden folding rulers, rulers, steel tape measures, steel rulers, etc. ２２: What are the commonly used tools for staking? answer: There are planning rules, ground rules, sample punches, marking needles, and small hand hammers. 23: What is the procedure for setting out full scale? answer: The procedures are linear lofting, structural lofting, and unfolding lofting. 24: What does the expansion look like? answer: There are plate thickness processing, unfolding drawings, and number material sample production. 25: What types of templates are classified according to their uses? answer: There are material samples, type verification samples, and positioning samples. 26: What materials are generally used to make samples? answer: Use thin iron sheet with a thickness of 0.5--2 mm. 27: What are the main methods of drawing models and sample poles? answer: There are straight line drawing method and transition drawing method. 28: How to use materials rationally? answer: It is necessary to concentrate on arranging and utilizing remaining materials. 29: What types of curves are there? answer: Divided into plane curves and space curves. 30: What are the methods to find the real length of a straight line segment? answer: There are rotation method, right triangle method, branch line method, and surface changing method. 31: What are the steps to expand this? answer: Through geometric drawing, we first draw intersecting lines, real long lines, and real cross-section shapes, and then make an expanded diagram. 32: What is the basic method for finding plane-solid intersection lines? answer: Edge method and edge method. 33: What is the basic method for finding the intersection line of a curved surface? answer: It is the longitude method and the latitudinal method. 34: What is the main method of finding intersecting lines? answer: They are the auxiliary plane method, prime line method, and spherical method. 35: What are the characteristics of intersecting lines? answer: (1) The intersecting line is the common line and dividing line between two intersecting shapes. (2) Since the shape has a certain range, the intersecting line is always closed. 36: What is an intersection line? answer: The intersection of the cutting plane and the solid surface. 37: What is a prime line? answer: Any position of the busbar on the surface of the component is called a prime line. 38: What are the commonly used expansion methods? answer: There are parallel line method, radial line method and triangle method. 39: What are the common ways to divide a sphere? answer: There are banding method, block method and splitting method. 40: What are the main contents of plate thickness processing? answer: Determine the neutral layer of the bent part and eliminate plate thickness interference. 41: How is the material length of angle steel bent parts calculated? answer: Calculated based on center of gravity layer. 42: What types of shears are there for cutting straight lines? answer: There are gantry bevel shearing machines, horizontal beam bevel shearing machines, and combined punching and shearing machines. 43: What kinds of machine tools are there for shearing curves? answer: There are disc shearing machines and vibrating shearing machines. 44: What are the characteristics of vibrating shears? answer: The vibrating shear can cut various curves and inner holes. 46: What does a combined shearing and punching machine consist of? answer: It consists of diagonal shears, steel shears and small punches. 47: Try to analyze the transmission sequence of the shearing machine. answer: The sequence is from the original moving parts - transmission parts - workpiece. 48: What is the function of the front and rear baffles of the gantry shearing machine? answer: Mainly plays a positioning role. 49: What are the forms of positioning shearing on a gantry or oblique shearing machine? answer: There are shear plate positioning shears, tailgate positioning shears, and baffle positioning shears. 50: What can the shear force exerted by diagonal shears on the material be decomposed into? answer: It can be divided into shear force, horizontal tension force and separation force. 51: What materials are not suitable for shearing machines? answer: Not suitable for cutting alloy materials and quenched materials. 52: How to choose cutting oxygen pressure? answer: The selection should be based on the thickness of the workpiece, the diameter of the cutting torch nozzle, and the purity of oxygen. 53: What is the ignition point of general carbon steel in oxygen? answer: About 1100--1150°c 54: What metal materials can meet the conditions of gas cutting? answer: There are pure iron, low carbon steel, medium carbon steel and ordinary low alloy steel. 55: What is the process of gas cutting? answer: It’s the preheating of the metal, the burning of the metal, and the oxides being blown away. 56: What is the function of round die? What does it consist of? answer: It is a tool used to process external threads. It consists of a cutting part, a positioning part, and a chip removal hole. 57: What does the form of the bevel have to do with? answer: And the type of material, thickness, welding method, mechanical properties of the product. 58: What is frosting? answer: Processing the surface of a workpiece with a grinding wheel is called grinding. 59: What are the main types of grinding tools? answer: There are pneumatic grinders and electric grinders. 60: What deformation will occur to steel during the bending and forming process? answer: Elastic deformation and plastic deformation occur. 61: What are the bending and forming methods commonly used by riveters? answer: There are cold bending, hot bending, manual bending and mechanical bending. 62: What are the forms of material bending deformation during press bending? answer ； There are free bend, contact bend, and correction bend. 63: What is related to the change in the cross-sectional shape of the material during bending? answer: It is related to the relative bending radius, cross-sectional geometric characteristics, and bending mode. 64: What is the method to prevent the blank from deflecting during bending? answer: There are supporting devices and positioning holes. 65: What types of rolling bending machines are included? answer: Including plate rolling machines and steel rolling bending machines. 66: What are the main processes of manual pipe bending? answer: There are marking lines, sand filling, and heating and bending. 67: What are the connection methods for metal structures? answer: There are three types: rivet connection and threaded connection and welding. 68: What should you consider when choosing a join method? answer: Factors such as the strength of the components, working environment, materials, construction conditions, etc. should be considered. 69: What are the forms of riveted joints? answer: There are butt joints and corner joints. 70: What are the forms of solid rivet heads? answer: There are semi-round heads, countersunk heads, and semi-suspended heads. 71: What are the main types of AC arc welding machines? answer: There are BX1--330 type and BX--500 type. 72: What is the basic operation process of hot riveting? answer: Fastening of riveted parts, repairing holes, heating rivets, connecting and threading nails, pushing nails, and riveting. 73: What are the types of riveting? answer: There are strong riveting, tight riveting, and tight riveting. 74: What tools are used for repairing holes? answer: There is a reamer. 75: What are the commonly used anti-loosening measures for threaded connections? answer: It increases friction and mechanically prevents loosening. 76: What does a welding arc consist of? answer: It consists of anode area, cathode area and arc column. 77: What are the main types of welding machines? answer: There are DC welding machines and AC welding machines. 78: What is local deformation? What is included? answer: Refers to the deformation that occurs in a certain part of the component, including angular deformation, wave deformation, and local unevenness. 79: What types of welding are classified according to spatial location? answer: Divided into flat welding, vertical welding, horizontal welding and overhead welding. 90: During the welding process, in what three directions does the welding rod move? answer: There is movement toward the molten pool, movement along the welding direction, and lateral swing. 91: What are the three elements of assembly? answer: It is positioning, supporting and clamping. 92: What are the manual clamps? answer: There are spiral clamps, wedge clamps, lever clamps, and eccentric clamps. 93: What are the non-manual clamps? answer: There are pneumatic clamps, hydraulic clamps, and magnetic clamps. 94: What are the functions of spiral clamps? answer: It has the functions of clamping, pressing, lifting and supporting. 95: What are the commonly used measurement items in assembly? answer: There are linear dimensions, parallelism, perpendicularity, coaxiality, and angles. 96: What is the support form of the workpiece in assembly? answer: There are assembly platform supports and assembly tire frame supports. 97: What types of tire frame assembly can be divided according to their functions? answer: It can be divided into general tire frame and special tire frame. 98: What are the commonly used positioning methods in assembly? answer: There are line positioning, template positioning, and positioning component positioning. 99: What are the basic methods for finding plane intersection lines? answer: There are edge method and edge method. 100: Hot riveting generally consists of four people. What is their division of labor? answer: One person heats and transfers the heat, another person connects the nails and threads them, another person pushes the nails, and another person rivets them. 101: What is the function of the flat tail in a tapered shank drill bit? answer: It is used to increase the transmitted torque and prevent the drill bit from being punched in the spindle hole or drill bushing. 102: What is the function of the guide part in the drill bit? answer: It can maintain the straight drilling direction of the drill bit during the cutting process. At the same time, it has the function of smoothing the hole wall and is also the backup part of the cutting part. 103: What undesirable phenomena will occur when the hole is about to be drilled? answer: When the drill bit just drills through the workpiece, the axial resistance suddenly decreases. Due to the gap in the drilling machine's feed mechanism and the sudden recovery of elastic deformation, the drill bit will automatically cut in with a large feed amount, causing the drill bit to break or the drilling quality to decrease. 104: What is the role of cutting fluid when drilling? answer: Reduce friction, reduce drill bit resistance and cutting temperature, and improve the cutting ability of the drill bit and the surface quality of the hole wall. 105: What is cutting amount? answer: It is the general term for cutting speed, feed, and depth of cut. 106: What is grinding? answer: It is a method of processing the surface of the workpiece with a grinding wheel. 107: What is expansion? answer: The process of spreading the surface or part of a metal structure on a plane in sequence according to its actual shape and size is called unfolding. 108: How many ways are there to draw an expanded diagram? answer: There are parallel line method, triangle method and radial line method. 109: What are the expansion conditions for the parallel line method? answer: It means that the prime lines on the surface of the component are parallel to each other, and the real length is reflected on the projection surface. 101: What does plate thickness processing include? answer: Determine the neutral layer of the bent part and eliminate plate thickness interference. 102: What factors are related to the change in the position of the plate thickness neutral layer? answer: It is related to the bending radius of the sheet and the thickness of the sheet. 103: What are the general principles for processing the plate thickness of intersecting parts? answer: The expansion length is based on the size of the neutral layer of the component, and the height of the curve in the expansion diagram is based on the height of the contact point of the component. 104: What is the main content of staking? answer: Processing of plate thickness, unfolding drawings and making material templates based on the made component unfolding drawings. 105. What are the shearing equipment commonly used by riveters? answer: There are gantry shearing machines, oblique shearing machines, disc shearing machines, punching shearing machines and combined punching and shearing machines. 106: What types of plate rolling machines can be divided into according to the number and arrangement of rollers? answer: It is divided into three types: symmetrical three-roller, asymmetrical three-roller and four-roller. 107: What can punching dies be divided into according to their structure? answer: It is divided into simple mold, mold with guide pillar and composite mold. 108: What are the structural characteristics of the composite punching die? It has a convex and concave mold that functions as both a blanking convex mold and a punching convex mold. 109: What is punching force? answer: Refers to the maximum resistance of the material to the mold during blanking. 110: What stages can the deformation process of sheet metal separation during blanking be divided into? answer: It is divided into elastic deformation stage, plastic deformation stage and shearing stage. 111: What is the minimum bending radius? answer: The minimum radius that can be bent without damaging the material. 112: What are the common methods to reduce springback of press-bending parts? answer: There are correction mold method and pressure correction method. 113: What is the purpose of using a blank holder when stretching? answer: Mainly to prevent the edges of the stretch piece from wrinkling. 114: What is the function of the crank connecting rod mechanism of a crank press? answer: It can not only turn rotational motion into reciprocating linear motion, but also amplify force. 115: What does sheet metalworking manual forming include? answer: Including bending, arching, hemming, hemming, seaming and correction. 116: What are the functions of display templates? answer: It can be used for numbering materials, making separate molds and making milling templates. 117: What is putting aside? What are the formation methods? answer: The operation of stretching and thinning the edge material of the deformed part during the molding process is called edge setting. The formation methods include thinning and stretching. 118: What is fate? answer: The edge of the sheet is processed into a curved workpiece using the methods of edge pulling and edge closing. 119: What is hemming? answer: In order to increase the rigidity and strength of the edge of the workpiece, curling the edge of the workpiece is called crimping. 120: What is a seam bite? answer: The edges of two sheets or the two sides of one sheet are folded and pressed against each other, which is called a seam. 121: What is plate thickness processing? answer: A method adopted to eliminate the influence of plate thickness on the shape and size of the unfolded diagram. 122: What are the general steps for calculating the unfolded length of a bent part? answer: Divide bent parts into straight segments and arc segments ； Calculate the length of each segment separately ； Add the calculated lengths. 123: Under what circumstances should the incision cutting of section steel be used? answer: Angle steel, channel steel, and I-beam are bent into corners. 124: What are the stages of the entire blanking process? Answer: It is divided into three stages. elastic deformation stage ； plastic deformation stage ； Shearing stage. 125: What is blanking? answer: The stamping process uses a stamping plate to separate one part of the sheet from another part along a certain closed line. 126: How many types of bolt connections are there? answer: There are two kinds: Connections subjected to axial tensile loading ； Connections subject to lateral action. 127: What are the anti-loosening measures for bolted connections? answer: increase friction ； Mechanical anti-loosening. 128: What are the methods for mechanical anti-loosening? answer: cotter pin ； Stop washer ； stop washer ； Series wire. 129: What is welding arc? answer: A strong and long-lasting discharge occurs in the gas medium between the two electrodes. 130: What parts does the welding arc consist of? answer: from the cathode area ； It consists of anode area and arc column. 131: What are the three directions of movement of the welding rod? answer: Move towards the molten pool ； Move in the welding direction ； Make a horizontal swing. 132: How many types of welds can be classified according to their spatial position? answer: It is divided into flat welding, vertical welding, horizontal welding and overhead welding. 133: What are the characteristics of intersecting lines? answer: It is both the common line and the dividing line between the surfaces of the two bodies. ； Space is always closed. 134: What is an intersecting line? answer: A component composed of the intersection of two or more geometric bodies. 135: What are the factors that affect blanking quality? answer: Mold clearance ； The center lines of the convex and concave molds do not overlap ； The working edge of the mold is worn and dulled. 136: What are the general principles of mold design? answer: On the premise of ensuring stamping quality, we strive to design molds that are easy to manufacture, simple in process, low in cost, and convenient to use. 137: What is the purpose of calculating rolling force? answer: It is to choose the calendering equipment correctly. 138: What is free bending? answer: When the bending is completed, the punch, blank, and die are matched with each other and no impact will occur. 139: What is corrective bending? answer: Refers to the punch, blank, and die. After the three are matched, there is an impact, which corrects the bent parts. 140: What defects are likely to occur when pressing the head? answer: Wrinkling and bagging ； Straight edge pull marks and pits ； Microcracks on the outer surface ； Longitudinal tear ； Deflection ； oval ； The diameter is inconsistent. 141: What is expansion joint? answer: The deformation of pipes and tube plates is used to achieve sealing and tightening connections. 142: What is the purpose of calculating the punching force? answer: In order to reasonably select equipment capabilities and design molds. 143: What method can be used to reduce the punching force? answer: Inclined edge die ； Step die ； Heating the die. 144: What is the purpose of calculating bending force? answer: In order to select the bending press and design the mold. 145: What does the degree of tensile deformation include? answer: include: Degree of mold sticking ； The extent to which a material is allowed to deform in shape. 146: How to determine the number of drawings of a workpiece? answer: Based on the maximum deformation of the pulled workpiece and the material elongation. 147: How to determine the drawing coefficient? answer: It depends on the properties of the material, the draw wrap angle, the friction coefficient and whether the draw is prefabricated. 148: Which materials are not suitable for cold work? answer: High carbon steel, high alloy steel, cast iron and other brittle materials. 149: What is the correct sequence when angle steel undergoes complex deformation? answer: First correct the distortion, then correct the bend and finally correct the angular deformation. 150What are the causes of deformation of steel structures? answer: One is caused by external force, and the other is caused by internal stress. 151: What are the methods to eliminate welding residual stress? answer: Overall high temperature tempering ； Local high temperature tempering ； Temperature difference stretching method ； mechanical stretching method ； Vibration method. 152: What is overall welding deformation? answer: Refers to the changes in shape and size that occur throughout the structure. 153: What is the hammer expansion method? answer: The fibrous tissue of the metal sheet is elongated by hammering. 154: How is the rivet stem length determined? answer: It is determined based on the total thickness of the connected parts, the diameter gap between the nail hole and the nail rod, the riveting process and other factors. 155: What is the reason why the rivet head is too small after riveting? answer: Because the nail shaft is too short or the hole diameter is too large. 156: According to the different states of the metal during welding, how many types can it be divided into? answer: It is divided into three types: fusion welding, pressure welding and brazing. 157: What is fusion welding? answer: A method of using local heating to bring the welded joint to a molten state. 158: What is clamping? answer: It is to use external force to fix the positioned parts so that they can maintain their position during the processing process. 159: What is the six-point positioning rule? answer: Six positioning points are used to limit the freedom of the part in space to completely determine the spatial position of the part. 160: What is relative parallelism? answer: Refers to the parallelism of the measured line or surface on the part relative to the measurement datum line or surface. 161: What is relative verticality? answer: Refers to the perpendicularity of the measured line or surface on the part relative to the measurement datum line or surface. 162: What types of fixtures are used in assembly? answer: Assembly tools ； Assembly fixture ； Assemble the spreader. 163: What are the commonly used assembly spreaders? answer: There are wire ropes, iron chains, hand chain hoists and special spreaders. 164: How many guide forms do punching dies have? answer: There are two forms: guide posts, guide sleeves and guide plates. 165: How many parts does a punching die consist of? answer: It consists of working part, material positioning part, unloading part and mold base. 166: What is the role of the stretch die gap? answer: Reduce the friction between the material and the die and control the flow of material in the cavity of the die. 167: How many types of bite seams can be classified according to their structure? answer: Can be divided into vertical single bite seam ； Vertical double bite seam ； Horizontal flat seams and various angle seams. 168: What is the reason why the bent part springs back when the external force is removed? answer: This is because when the sheet is bent manually, the outer surface of the sheet is stretched and the inner surface is compressed, causing rebound. 169: How to get cold camber and hot camber? answer: Cold camber is obtained by shrinking the edges of the sheet and spreading the center of the sheet, and hot camber is obtained by shrinking the sheet through heating. 170: How many ways are there to get married? answer: There are two types, one is to use a general tool to remove the edge, and the other is to use a molded tire to remove the edge. 171: What is edge closing? answer: Edge closing is to wrinkle the sheet first, and then flatten the wrinkles to prevent stretch recovery. In this way, the shrinkage length of the sheet is reduced and the thickness is increased. 172 ； What is the basic principle of edge closing? answer: The principle is that for the forming of convex curved edge workpieces, the outer edge material of the curved flat edge shrinks and becomes thicker and shorter, forcing the vertical edge to take on a curved shape. 173: What is the purpose of correction? answer: By applying external force or local heating, the longer fibers are shortened and the shorter fibers are elongated, and finally the fibers in each layer are aligned to achieve the purpose of correction. 174: What is the principle of flame correction? answer: It uses the deformation caused by local heating of metal to offset the original deformation to achieve the purpose of correction. 175: What are the factors that affect the flame correction effect? answer: Have the rigidity of the workpiece ； heating position ； flame heat ； Heating area and cooling method. 176: What are the heating methods for flame correction? answer: There are points, lines and triangles for heating. 177: What are the factors that determine process margin? answer: There is the influence of setting out error ； The impact of errors during part processing ； The impact of assembly errors ； Effect of welding deformation ； Effect of flame correction. 178: What categories can templates be divided into based on their uses? answer: It can be divided into numbering templates, forming templates, positioning templates and sample rods. 179: What are the methods of drawing? answer: There are two types, the direct drawing method and the transitional drawing method. 180: How to generally choose the lofting baseline? answer: Take two mutually perpendicular lines or surfaces ； Take the two center lines as the baseline ； Use a plane and a centerline as a baseline. 181: What is the allowable error for setting out? answer: During the setting out process, due to the influence of factors such as the accuracy of setting out measuring tools and tools, as well as the level of operation, there will be a certain size deviation in the actual sample drawing. Controlling this deviation within a certain range is called the setting out allowable error. 182: What does structural lofting include? answer: Determine the joint position and connection form of each part ； Make necessary changes based on actual production and processing capabilities ； Calculate or measure the material length of parts and the actual shape of flat parts ； Design the tire mold or frame. 183: What are the methods of finding the real length of a straight line segment? answer: rotation method ； right triangle method ； Changing sides ； Branch method. 184: What is the drawing rule for finding the real length of a line segment using the right triangle method? answer: The projection of the line segment on any projection plane is used as one right-angled side of the right triangle, and the projection length of the corresponding projection on the axis perpendicular to the plane is used as the other right-angled side, and its hypotenuse is the actual length of the line segment. 185: What is the rotation method to find the real length? answer: It is to rotate the general position of space around a fixed axis into a parallel line, and then the projection of the line on the projection plane parallel to it reflects the real length. 186: What are the methods to find the actual length of a curve? answer: There is a method of changing faces ； expansion method. 187: What is face-changing method? answer: That is to say, if a new projection surface is parallel to the curve, then the projection of the curve on this surface will reflect the real length. 188: What is the expansion method? answer: The expansion line is obtained by straightening one length in the curve view while keeping the height in the other view unchanged. 189: What are the basic characteristics of intersection lines? answer: The intersection line must be a plane figure surrounded by closed straight lines or curves ； The intersection line is the common line between the section plane and the three-dimensional surface, and is formed by the collection of points that are both on the section plane and on the three-dimensional surface. 190: What are the methods for finding solid intersection lines? answer: Facet method ； Edge method. 191: What are the methods for finding the three-dimensional intersection line of a curved surface? answer: Plain line method and weft line method. 192: What are the characteristics of intersecting lines? answer: One is the common line that intersects the surfaces of two shapes, and is also the dividing line between two intersecting shapes. ； Second, the intersecting lines are all closed. 193: What is the essence of finding intersecting lines? answer: It is to find a certain number of common points on the surfaces of the two shapes, and connect these common points in sequence to achieve the desired result. 194: What are the selection principles for finding intersecting line methods? answer: To find the intersecting line using the prime line method, at least one projection of the intersecting line must be known ； Use the auxiliary plane method to find the intersection line. The intersection line should be the simplest geometric figure. ； The spherical method is only applicable to components whose bodies of revolution intersect and whose axes intersect. 195: Under what conditions does the intersecting line become a plane curve? The front projection of a curve is two intersecting straight lines? answer: When two arbitrary rotating bodies circumscribed on the same spherical surface intersect, their intersecting line is a plane curve. At this time, when the axes of the two rotating bodies are parallel to their basic projection plane, the projection of the intersecting line on the plane is two intersecting straight lines, 196: What is a ruled surface? answer: It is the surface formed by using straight lines as the generatrix. 197: What are the characteristics of cylinders? answer: All prime lines are parallel to each other ； When a cylinder is cut with parallel planes, the cross-sectional shapes will be the same. 198: What are the characteristics of a cone? answer: All prime lines intersect at a point ； When a cone is cut with parallel planes, its cross-sectional shapes are similar ； The intersection line through the top of the cone is a triangle. 199: What are the stages of the plastic deformation process of the material during stretching? answer: Material bends ； Material is stretched and deformed ； Make up. 200: What is pull shape? answer: It is a forming method in which the sheet material is plastically deformed according to an ideal curved surface under tension and overcomes springback. 201: What does plate thickness processing include? answer: Determine the neutral layer of the bent part and eliminate plate thickness interference. 202: What factors are related to the change in the position of the plate thickness neutral layer? answer: It is related to the bending radius of the sheet and the thickness of the sheet. 203: What are the general principles for processing the plate thickness of intersecting parts? answer: The expansion length is based on the size of the neutral layer of the component, and the height of the curve in the expansion diagram is based on the height of the contact point of the component. 204: What is the main content of staking? answer: Processing of plate thickness, unfolding drawings and making material templates based on the made component unfolding drawings. 205What are the shearing equipment commonly used by riveters? answer: There are gantry shearing machines, oblique shearing machines, disc shearing machines, punching shearing machines and combined punching and shearing machines. 206: What types of plate rolling machines can be divided into according to the number and arrangement of rollers? answer: It is divided into three types: symmetrical three-roller, asymmetrical three-roller and four-roller. 207: What can punching dies be divided into according to their structure? answer: It is divided into simple mold, mold with guide pillar and composite mold. 208: What are the structural characteristics of the composite punching die? It has a convex and concave mold that functions as both a blanking convex mold and a punching convex mold. 209: What is punching force? answer: Refers to the maximum resistance of the material to the mold during blanking. 210: What is rebound? answer: During the bending process, when the external force is removed, the material's recovery phenomenon due to elasticity is called springback. 211: What is stretching? answer: A stamping process that uses a press and corresponding molds to make open hollow parts from sheet metal. 212: What is the stretch coefficient? answer: The ratio of the cross-sectional area of ​​the material after each stretch to the end area before stretching is called the stretch coefficient of that time. The tensile coefficient actually reflects the degree of deformation of the tensile part. 213: What is the edge circle? answer: During the stretching process, in order to prevent the edge of the workpiece from becoming unstable and wrinkling, a ring-shaped pressing device is installed at the edge between the concave and convex molds. 214: How does a friction press work? answer: The working principle of friction press is: It uses the contact transmission of flywheel and friction plate, and works by the principle of relative motion of screw and nut. 215: What are the advantages of friction presses? answer: The action is fast and the slider can stop at any position within the stroke. Once overloaded, it will only cause sliding between the flywheel and the friction plate without damaging the machine parts. 216: What are the advantages of the stamping process? answer: (1) High production efficiency. One stroke of the press can complete one process, and sometimes multiple processes. (2) High material utilization rate. (3) The shapes and sizes of stamped parts of the same product are consistent and have good interchangeability. (4) It is simple to operate and facilitates mechanized and automated production. 217: How many categories are the stamping processes divided into? answer: (1) Separation process (2) Forming process (3) Composite process. 218: What is blanking? answer: A stamping method that uses dies to separate sheet metal on a press. 219: How to distinguish punching and blanking? answer: Generally, the sheet material is formed into two parts after punching, namely the punched-out part and the holed part. If the purpose of punching is to produce a workpiece with a certain shape, that is, the punched out part is called blanking.: On the contrary, the purpose of blanking is to process an inner hole of a certain shape, and what is punched out is waste material, which is called punching. 220: What are the stages of material separation during blanking? answer: Elastic deformation, plastic deformation, cracking and separation. 221: How many methods are there to reduce punching force? answer: There are three kinds: (1) Inclined edge punching (2) Stepped punch punching (3) Blank heating and punching. 222: What is the minimum bending radius? answer: The minimum limit value of the bending radius that does not cause damage during bending of a material is called the minimum bending radius. 223: What types of external forces cause deformation of structural parts? answer: Including bending force, torsion, impact force, tension, pressure, etc. 224: What can happen inside a component caused by external forces? When the external force is removed, part of the internal force may remain, and what will form? answer: External forces can cause internal forces to appear inside components: When the external force is removed, internal stress is formed. 225: What is the welding process for metal structural parts? What is the main cause of deformation of components? answer: is an uneven heating and cooling process: It is the main cause of deformation caused by internal stress in components. 226: In which directions does the shrinkage of the weld and the metal near the weld mainly manifest itself? answer: Mainly manifested in shrinkage in both longitudinal and transverse directions. 227: What are the factors that may cause deformation of structural parts in terms of design? answer: There are structural rationality, weld position, welding groove form, etc. 228: What are the factors that may cause deformation of structural parts in terms of process? answer: Welding process regulations, welding sequence, anti-deformation measures, etc. 229: What is the prerequisite for completing correction work with quality and quantity? answer: The premise is: Correct judgment and selection of correction location. 230: When analyzing the causes of component deformation, it is necessary to distinguish what causes the deformation? answer: It is necessary to distinguish whether deformation is caused by external force or internal stress. 231: What are the three deformations of Gong-shaped beams? answer: There are arch deformations, side bends, and corner deformations. 232: What are the two types of deformations of box beams? answer: There is arch deformation and distortion. 233: What is the main contradiction when the two deformations of box-shaped beams appear at the same time? In what order should correction be performed? answer: Distortion is the main contradiction. It should be carried out in the order of twisting first and then arching deformation. 234: What is internal force? answer: When an object is deformed by an external force, a force that resists deformation appears inside the object. This force is called internal force. 235: What is stress? answer: When an object is acted upon by an external force, the internal force that appears on the unit cross-sectional area is called stress. 236: What is internal stress? answer: When there is no external force acting, the stress existing inside the object is called internal stress. 237: What is local deformation? answer: Deformation of a certain part of a component is called local deformation. 238: What is overall deformation? answer: Changes in the shape and size of the entire component are called overall deformation. 239: What is shrinkage deformation? answer: One of the basic forms of deformation mostly refers to the deformation in which an object is shortened and deformed after being heated and cooled. 240: What is distortion? answer: One of the basic forms of deformation is a deformation in which the length of an object does not change, but its straightness exceeds the tolerance. 241: What is angular deformation? answer: One of the basic forms of deformation is when the angle formed between parts of an object changes beyond the tolerance, which is called angular deformation. 242: What is a correction site? answer: The position where correction means is applied to the deformation of the steel structure, sometimes the correction part is not necessarily the deformation part of the component. 243: What are steel structural components? answer: A variety of parts are connected together through various methods such as welding, riveting or bolting. These parts are interconnected and restrict each other to form an organic whole, usually called steel structural parts. 244: What are the causes of deformation of steel structural parts? answer: There are two reasons: (1) Deformation caused by external force (2) Deformation caused by internal stress. 245: What are the basic forms of welding deformation? answer: Longitudinal and transverse shrinkage deformation, bending deformation, twisting deformation, and angular deformation. 246: What are the characteristics of using thin steel plates in steel structures? answer: Thin plates used in steel structures are often assembled or welded together with various types of frames and are limited by the frames. 247: The degree of cross-sectional deformation when the pipe is bent depends on the values ​​of the relative bending radius and relative wall thickness, right? answer: right. 248: When the pipe is bent, the greater the relative bending radius and relative wall thickness, the greater the deformation, right? answer: wrong. 249: If the curvature of the bent pipe is not enough but similar, we can use water cooling on the outside of the pipe to shrink the metal on the inside to increase the curvature, right? answer: wrong. 250: At present, in general on-site pipe bending, when the requirements for bending deformation cross-section ovality are not too strict, anti-deformation devices are often not installed when using coreless pipe bends, right? answer: wrong. 251: According to the transmission mode, pipe bending machines are divided into two types: mechanical transmission and gear transmission, right? answer: wrong. 252: There are two travel switches on the pipe bending machine. The required bending length can be controlled by adjusting the position of the stopper, right? answer: right. 253: The characteristics of the hydraulic pipe bending machine are smooth transmission, reliability, low noise, compact structure, and the ability to bend different pipe blanks, right? answer: wrong. 254: The method of bending or shaping a blank by rotating an axis is called roll bending, right? answer: right? 255: The advantage of roll bending is its strong versatility. When rolling sheet metal, it is generally necessary to add other process devices to the rounding machine, right? answer: right. 256: In order to take out the bent cylindrical workpiece, both ends of the supporting part of the upper shaft roller are movable and the workpiece can be taken out, right? answer: wrong. 257: During the roll bending process, you should always check with a template. It is best not to roll the curvature too small, right? answer: wrong. 258: What are the methods of bending and forming? answer: There are pressure bending, pull bending, bending and manual bending, etc. 259: During the bending process, by adjusting the upper and lower rollers, the blank can be bent to any curvature smaller than the upper roller curvature. answer: Just adjust the relative position of the upper and lower rollers. 260: What are the two categories of rounding machines? answer: There are two categories: discrete and horizontal. 261: Horizontal spheronizing machines are divided into three-axis and four-axis. What are the two types of three-axis? answer: There are two types: symmetrical and asymmetrical. 262: What is the shape of the roller cores of the three rollers of the symmetrical three-axis rounding machine? answer: into an isosceles triangle. 263: When the material is rolled into a cylinder, the distance between the rollers must be adjusted to keep the centers of the rollers aligned with each other. answer: Be sure to keep the centers of the rollers parallel to each other, otherwise the workpiece will taper. 264: When the pipe is bent, what force is exerted on the material outside the neutral layer to cause the pipe wall to become thinner? What force is exerted on the material inside to make the pipe wall thicker? answer: The effect of tensile stress causes the pipe wall to become thinner: The effect of compressive stress causes the pipe wall to thicken. 265: When the pipe is bent, because the cross-section is circular and has insufficient stiffness, what can easily happen when it is bent in a free state? answer: It is prone to flattening and deformation. 266: What are the main processes of manual pipe bending? answer: The main processes are sand loading, marking, heating and bending. 267: When bending a seamed pipe blank, where should the pipe seam be located? answer: center layer. 268: What tests must be carried out on the bent part of the bent pipe to check whether there are any phenomena? answer: Be sure to perform a pressure test to check for leaks. 269: How to eliminate the straight start of the asymmetric three-roller rounding machine? answer: With the asymmetrical three-axis rounding machine, the rolled workpiece only has a straight end at the beginning. As long as the workpiece is turned over and rolled again after the first rolling, the straight ends at both ends can be eliminated. 270: What is the anti-transformation method? answer: That is, before the tube blank enters the bending deformation zone, a certain amount of deformation is given in advance to make the outside of the tube wall bulge to offset or reduce the deformation of the cross-section during bending. 271: When assembling T-shaped beams in small batches or single pieces, what assembly method is generally used? answer: Use scored lines to assemble. 272: When assembling T-shaped beams and I-shaped beams, what assembly is generally used to further increase the assembly speed? answer: Use mold assembly. 273: The longitudinal shrinkage of a weld decreases as the length of the weld increases, right? answer: wrong. 274: The railing of the bridge crane is a truss structure, and its upper camber is the same as the main beam, right? answer: right. 275: Box beams, bridges, and frames must also have a certain camber, and the camber in the middle should be greater than the allowable deflection of the beam, right? answer: wrong. 276: Due to the self-weight of the bridge and the influence of welding deformation, the prefabricated camber of the box girder web should be greater than the camber of the main beam, right? answer: right. 277: When the steel plate is thin and the weld is in the middle of the steel plate, what kind of deformation often occurs after welding? answer: Wave deformation occurs. 278: When the weldment itself cannot overcome the function of the weld, will it cause deformation of the weld body? answer: When the weldment itself cannot overcome the shrinkage of the weld, it will cause deformation of the weld body. 279: What are the methods to prevent and reduce welding deformation? answer: There are anti-deformation methods, correctly selected welding sequences, rigid fixing methods, and hammer welding methods. . 　 280: What are called parallel lines to this projection surface? What is the property of the projection of this straight line? answer: When a straight line is parallel to the projection surface, it is called a parallel line to the projection surface. The projection of this straight line has realism. 281: Any metal sheet has a thickness, and the thickness of the sheet affects the shape and size of the drawing? answer: It has an impact on the shape and size of the expanded diagram. 282: How do the surfaces of spheres, rings, and spiral components develop curves? answer: Its surfaces are all undevelopable surfaces. 283: What expansion method is generally used for the expansion of prisms and cylinders? answer: Generally, the parallel line expansion method is used. 284: If a conical tube and a cylindrical tube intersect at right angles, what method is often used to find the intersection line? answer: It is often obtained using the auxiliary plane method. 285: Which method is most commonly used to find the real length of a curve? answer: Use expansion method frequently. 286: When a friction press is overloaded, it will only cause sliding between what, but not damage to the machine parts? answer: It will only cause slippage between the flywheel and the friction plate, but will not damage the machine parts. 287: The stroke of the slide of an open crank press can be adjusted by changing what and what? answer: By changing the eccentric sleeve on the upper part of the connecting rod ； Adjust the center distance of the spindle. 288: In the deep drawing and extrusion processes, what are the stricter requirements for materials due to the die gap? answer: The requirements for material thickness tolerance are strict. 289: What are the three stages of sheet metal separation process during blanking? answer: 1: elastic deformation, 2: Plastic deformation, 3: Crack separation. 290: The higher the drawing coefficient, the greater the degree of drawing deformation of the material? answer: The smaller the drawing coefficient, the greater the degree of drawing deformation of the material. 291: What is cold stamping? answer: Stamping processing performed at room temperature is called cold stamping. 292: What is a composite process? answer: Combining two or more basic processes and completing them in one stroke of the press is called a composite process. 293: What is a simple punching die? answer: In one stroke of the press, only one punching process can be completed. 294: What is a composite punching die? answer: In one stroke of the press, the punching die can complete multiple processes at the same time. 295: How to interpret the punching force correction coefficient Kp? answer: When calculating the punching force, factors such as the wear of the mold cutting edge, the mold gap, the mechanical properties of the material, etc. are taken into consideration, and the safety factor selected is, in general, Kp equal to 13.296.: What is oblique edge blanking? answer: Inclined edge punching is a method to reduce punching force. That is, the die edge is tilted at a certain angle relative to the blank, so that the contact between the die edge and the blank is gradual during punching, making the load uniform and stable. 297: What is stepped punch punching? answer: Step punch punching is a method to reduce the punching force. When punching multiple holes at the same time, the punch is made into a stepped form with different heights relative to the blank, which can effectively disperse the punching force during punching. 298: What is the difference between an open crank press and a closed crank press? answer: Structurally, the bed of an open crank press has a C-shaped structure, and the connecting rod converts the rotary motion of the eccentric mandrel into the up and down reciprocating motion of the slider. The bed of the closed press has a frame-shaped structure, and the eccentric shaft is replaced by a crank. 299: What are the characteristics of open crank press and closed crank press? answer: The C-shaped bed of the open crank press is open on three sides and is particularly suitable for stamping the edges of large sheets. However, this form of bed structure itself has poor rigidity and therefore can withstand smaller loads. The frame structure of the closed crankshaft press is limited by the columns, the workbench area is limited, and the operating space is small. Therefore, there are certain restrictions on the peripheral dimensions of the stamping parts. The frame-shaped structure of the bed has good rigidity and the load it bears is large and uniform. 300: What are the factors that affect material stamping? answer: There are (1) elasticity (2) plasticity (3) hardness (4) surface state quality of the material (5) thickness tolerance of the material. 301: What impact does die clearance have on blanking quality? answer: If the gap between the convex and concave dies is too small, the cracks in the material near the cutting edge of the convex mold will be staggered outward by a certain distance. In this way, part of the material between the upper and lower grooves will be sheared a second time as the blanking proceeds, affecting the cross-sectional quality. When the gap is too large, the cracks in the material near the punch edge are staggered inward for a certain distance, and the material is greatly stretched. The burrs, sagging angles and slopes on the edge of the material will also affect the cross-sectional quality of the blanking parts. In addition, if the gap is too small or too large, it will have a certain impact on the dimensional deviation of the blanking parts. 302: What are the factors that affect the minimum bending radius of materials? answer: 1: Mechanical properties and heat treatment status of materials, 2: Bending angle of workpiece, 3: Material geometry and dimensions, 4: Bending direction, 5: Other aspects, such as the thickness of the material, the quality of the surface and sides, etc. 303: How is the neutral layer of a material defined during bending? answer: During the bending process of the material, the outer layer is stretched and the inner layer is squeezed. There must be a transition layer on the cross section that is neither stretched nor compressed. The stress is almost equal to zero. This transition layer is called the neutral layer of the material. 304: When correcting components composed of multiple beams and columns, what joint relationships should be fully considered? answer: Fully consider the joint relationship between beams and columns. 305: When correcting the deformation of thin plates in steel structures, what must be ensured to meet the requirements? answer: It is necessary to ensure that the various types of frames meet the requirements before the sheet can be considered for correction. 306: What does the heating point of point heating have to do with the plate? What is the distance between heating points? answer: The heating point of point heating is related to the thickness of the plate. The distance between heating points should be even and consistent. 307: What is longitudinal shrinkage? answer: A form of shrinkage of the weld and the metal near the weld, shrinkage along the length of the weld, is called longitudinal shrinkage. 308: What is lateral shrinkage? answer: A form of shrinkage of the weld and the metal near the weld, which refers to the shrinkage perpendicular to the length of the weld, is called lateral shrinkage. 309: How are internal stresses generated in steel structural parts? answer: The welding process is an uneven heating and cooling process for riveted welded structures, which is the main cause of internal stress in riveted welded structural parts. In addition, each part in the steel structure may have residual stress in its blank state or after being processed into parts. After being assembled and welded into a whole, these residual stresses may aggregate into new internal stresses in the component. 310: Why do some steel structural parts need to undergo stress relief treatment after welding? answer: After welding, some steel structural parts have no obvious welding deformation due to their good rigidity, but the welding stress is quite large. After the steel structure is used for a period of time, it may be released for some reason, causing deformation and even damage. Therefore, for some important steel structures, such as high-pressure vessels, hazardous medium containers, boilers, etc., various methods are used for stress relief treatment after welding. The purpose is to prevent the internal stress in the steel structure from causing harm to the components. 311: What are the factors that affect the welding deformation of steel structural parts? answer: The factors that affect the welding deformation of steel structural parts include design and process. The design aspect refers to the rationality of structural design, the location of welds, the form of welding grooves, etc. The process aspect refers to the reasonable welding process regulations, assembly and welding sequence, the use of various anti-deformation and anti-deformation methods, and the stress relief measures taken. 312: How to understand the intrinsic relationship of steel structure parts? answer: The so-called steel structural parts are a variety of parts connected into one body through various methods such as welding, riveting or bolting. These parts are connected with each other and restrict each other to form an organic whole. 313: What are the key points to correct the deformation of steel structure parts? answer: 1: Analyze the causes of component deformation and find out whether the deformation is caused by external force or internal stress, 2: Analyze the internal connections of components and clarify the mutual constraints of various parts, 3: Choose the correct correction site, resolve the main contradiction first, and then resolve the secondary contradictions, 4: It is necessary to understand and master the properties of the steel used in the components in order to prevent the workpiece from breaking, cracking or springing back during correction. 5: Determine the correction method according to the actual situation, and the order in which multiple methods should be used together. 314: Which method can only be used to correct the deformation of thin plates in steel structural parts?: For the deformation of thin plates in steel structures, local heating (and point heating) can only be used to correct it. 315: What aspects should be paid attention to when spot heating corrects the deformation of thin plates? answer: It should be noted: 1: The heating temperature should be appropriate, which should be enough to cause plastic deformation of the steel, but not too high, generally 650-800. 2: The size of the heating spots and the distance between them should be appropriate. Generally speaking, depending on the thickness of the board, the arrangement should be uniform, usually in a plum blossom shape. 3: The purpose of watering, rapid cooling and wooden hammering is to accelerate the shrinkage of the fiber group of the steel plate. 4: When heating, the gas welding torch should not rock back and forth, the small flame beam should be vertical to the steel plate, and there should not be too many heating points to avoid increasing undue internal stress. 316: What are the characteristics of the deformation of frame components? answer: There are many parts in frame components, which have strong mutual constraints in the structure, and the mutual influence of deformation is great. 317: When the billet is rolled and bent by the simmering machine, it is usually done after heating, right? answer: wrong. 318: When heat bending, to what degree should the material be heated? How about simultaneous heating? How does it work? How low will the final temperature be? answer: The material should be heated to 950-1100. At the same time, the heating should be uniform, and the final temperature should not be lower than 700. 319: What are the possible defects that may occur when bending a cylinder? answer: Defects that may occur when rolling and bending the cylinder include distortion, unequal curvature, excessive curvature, and drum shape in the middle. 320: When rolling and bending a cone, as long as the center of the upper shaft is adjusted to what position and the axis of the roller always coincides with the generatrix of the sector-shaped blank, can it be rolled into a cone shape? answer: Adjust to tilt position. 321: When rolling a cone, which edge of the blank is increased in friction? Make what moves slower than what moves faster? answer: Increase the friction of the small opening of the blank so that the speed of the small opening is lower than the speed of the large opening. 322: There are many types of shafts for cored bent pipes, including round-headed ones, pointed-headed ones, hooked ones and what else? answer: And one-way joint type, universal type, etc. 323: Coreless pipe bending does not require a mandrel. What process is used on the pipe bending machine to control the deformation of the pipe? answer: The anti-deformation process is used on the pipe bending machine to control the deformation of the bent pipe section. 324: When the bending radius of the elbow is greater than how many times the diameter, coreless elbows are generally used? answer: greater than 1. 5 times. 325: Extrusion bending uses the plasticity of metal to press the pipe blank into a mold with what kind of mold at normal temperature to form a pipe elbow? answer: The pipe blank is pressed into a bending mold to form a pipe elbow. 326: When extruding a bent pipe, in addition to the moment of the bending force, what force does the pipe blank also act on and what force is opposite to the axial force? answer: It is also affected by friction forces in the axial direction and in the opposite direction to the axial force. 327: Briefly describe the process of rolling and bending blanks with a rounding machine? answer: During roll bending, the blank is placed on the rounding machine between the lower rollers. Due to the rotation of the rollers and the friction between the upper and lower rollers and the blank, the blank moves, thus continuously forming bends. 328: What are the advantages of four-axis rounding machines? answer: The advantage of the four-axis rounding machine is that both ends of the sheet can be rolled, thereby eliminating straight ends at both ends. Compared with the three-axis rounding machine, the process is simplified, the workload is reduced, and the production efficiency is improved. 329: What are the methods of rolling a cone? answer: It can be divided into partition rolling method, rectangular feeding method, rotating feeding method, small mouth deceleration method, etc. 330: How to reduce the ovality of the cross-section when bending pipe? answer: When bending pipes, in order to reduce the ovality of the cross-section, during the production process, fillers are often added to the pipes, or a roller with a conical groove is pressed on the outside of the pipe, or a mandrel is inserted into the inside of the pipe for bending. 331: What are the advantages of spoon mandrels? answer: The supporting surface between the spoon-type mandrel and the outer wall is large, and the anti-flattening effect is better than that of the pointed type. The surface is not easy to wrinkle when the pipe is bent. The spoon-type mandrel is also more convenient to manufacture, so it is widely used. 332: What are the advantages of coreless bent pipes over cored bent pipes? answer: (1) Reduce a lot of work such as core preparation before bending, thereby improving production efficiency (2) Avoiding the manufacturing of mandrels and reducing costs. (3) No lubrication is required inside the pipe, saving lubricant and oil injection processes. (4) The quality of the bent pipe is ensured. (5) There is no friction between the mandrel and the pipe wall, which reduces the torque when bending the pipe, thus extending the service life of the pipe bending machine. 333: How is the mechanical transmission pipe bending machine driven? answer: The mechanical transmission pipe bending machine is driven by an electric motor through a gear shaft, a reduction mechanism, and a worm gear to drive the pipe bending die to rotate. 334: When assembling the annular seam of connected cylinders on the roller frame, the lateral distance and height position of each pair of rollers cannot be the same, so that the cylinders can be concentric during assembly, right? answer ； wrong. 335 ； If there is a deviation in the diameter of the two cylinder sections, the cylinder section with the larger diameter should be raised during assembly to make the two cylinder sections concentric, right? answer: wrong. 336: The greater the linear expansion coefficient of the weldment material, the greater the shrinkage of the weld seam after welding, right? answer: right. 337: The post-weld shrinkage of carbon steel is greater than that of stainless steel and aluminum, right? answer: wrong. 338: When using the hammer welding method to prevent multi-layer welding from deforming, hammering should be applied to the first and last layers, right? answer: wrong. 339: Using a rigid fixation method will cause great internal stress in the weld area, so this method is suitable for medium carbon steel and alloy steel, right? answer: wrong. 340: What longitudinal seams are often used to assemble the cylinder to improve assembly efficiency? answer: Lever and screw tensioner are often used to improve efficiency. 341: What is often used to adjust the ovality of thin-walled cylinders? answer: Use radial pusher. 342: When slender cylindrical sections are butted together, what can be used to assemble them to ensure that the whole does not bend? answer: Assembling with a roller-type roller frame ensures that the whole unit does not bend. 343: When vertically installing butt joints, what kind of clamping and alignment can be used to clamp and align the circular seams to achieve better results while still obtaining the required gap? answer: Utilizing wedge clamps to clamp and align the ring seams provides better results and provides the required clearance. 344: What positioning should be used when vertically installing overlapping cylindrical ring seams? What is the final clamp? answer: Use retaining iron to position. Finally, clamp it with conical wedges. 345: What does a rivet gun mainly consist of? answer: It is mainly composed of handle, gun body, trigger, pipe joint, etc. 346: Before cold riveting, in order to eliminate hardening and improve the plasticity of the material, how must the rivets be treated? answer: Annealing is required. 347: What are blind rivets made of? answer: It is composed of hollow rivets and mandrels. 348: What happens in the weld area after the weld cools? What force is generated in the weld body? answer: After the weld seam cools, shrinkage occurs in the weld seam area, causing internal stress in the weld body. 349: During multi-layer welding, the shrinkage caused by the first layer is the largest. The shrinkage of the second layer is about several dozen percent of the shrinkage of the first layer? The third layer is approximately several dozen percent of the first layer? answer: (1) Twenty percent (2) Five to ten percent. 350: What is the general camber of the main beam of an overhead crane? answer: One thousandth. 351: What three parts does a bridge crane consist of? answer: Bridge frame, operating mechanism, load-carrying trolley. 352: What does the main beam of the box-row structure consist of? answer: It consists of upper cover plate, lower cover plate, web plate, long and short rib plates, etc. 353: For the web surface of the main girder of the box-row structure, what is the maximum allowable wave peak value for the pressure zone within one meter of length? What is the tension area? answer: For the compression zone it is 0.7t: for the tension zone it is 1.2t. 354: How much allowance is required when cutting out the webs of box beams? How far away from the center can there be a joint? answer: A margin of one and a half thousandths is required: There must be no joints two meters from the center. 355: There are various types and shapes of steel roof trusses according to their uses and needs. What are the general roof trusses? answer: There are triangle, trapezoid, spherical, mesh roof trusses, etc. 356: What is the general height of a triangular roof truss relative to its span? answer: It's one-quarter to one-fifth. seventy-eight: How much is the height of a trapezoidal roof truss relative to its span? answer: From one-sixth to one-twelfth. 357: What methods are commonly used to assemble steel roof trusses? answer: The profiling method is often used for assembly. 358: What is cold riveting? answer: Riveting of rivets at room temperature is called cold riveting. 359: What is riveting? answer: Blind riveting is another riveting method of cold riveting. It uses manual or compressed air as power to rivet the rivets and the riveted parts through special tools. 360: What is hot riveting? answer: Riveting after the rivets are heated is called hot riveting. 361: What is the anti-transformation method? answer: Analyze the direction and size of the deformation that may occur after welding. Before welding, the welded parts should be deformed in the same size and in the opposite direction to offset or compensate for the deformation after welding, so as to prevent post-weld deformation. This method is called the anti-deformation method. 362: What is rigid fixation method? answer: The method of using assembly fixtures or temporary supports to fix the mutual positions of welded parts to prevent deformation after welding is called the rigid fixing method. 363: The layout drawing is a drawing drawn based on the construction drawing, right? answer: wrong. 364: In addition to flat surfaces, there are also cylindrical and conical surfaces that can be developed, right? answer: right. 365: All the drawing lines on the expanded diagram are solid long lines corresponding to the corresponding parts on the component surface, right? answer: right. 366: If one of the projections of a line segment in the three-dimensional projection has accumulation properties, then the other two projections must be realistic, that is, reflect the real length of the line segment, right? answer: wrong. 367: If the two projections of a line segment are perpendicular to the projection axis between them, then the third projection must reflect the actual length of the line segment, right? answer: wrong. 368: The projection of a straight line is always a straight line and nothing else, right? answer: wrong. 369: Generally, the positional straight line in the three-dimensional view sometimes reflects the actual length and sometimes does not reflect the actual length, right? answer: right. 370: For the real length of a straight line in a general position, it is best to use the rotation method, right? answer: wrong. 371: The methods for finding the real length of a line segment include the parallel line method, the triangle method and the radial line method, right? answer: wrong. 372: Right triangle method, rotation method, surface changing method and branch line method are commonly used to draw expanded diagrams in riveting or sheet metal working production, right? answer: right. 373: When using the triangle method to expand a shape, the key is to find the real length of each prime line, right? answer: wrong. 374: Plane curves reflect real length in three views, right? answer: wrong. 375: Prisms, cylinders and cylindrical surfaces can all be expanded using the parallel line method, right? answer: right. 376: The triangle expansion method is suitable for the expansion of shapes where the prime lines on the surface of all components intersect at one point, right? answer: wrong. 377: When using the auxiliary surface method to find intersecting lines, the axes of the rotating body must be parallel and reflect the real length, right? answer: wrong. 378: What presses are commonly used by riveters? answer: There are hydraulic presses and pneumatic presses. 379: What effect does the final riveting temperature have on riveting? answer: If it is too high, it will reduce the initial stress of the nail rod. ； If it is too low, the rivets will become blue brittle380: What is the function of the shank of the drill bit? answer: Holds and transmits the torque and axial force required when drilling. 381: What types of hammers are commonly used by riveters? answer: There are hand hammers, sledge hammers, and type hammers. 382: What types of chisels are commonly used by riveters? answer: There are two categories: flat chisels and narrow chisels. 383: What is steel? answer: Iron-carbon alloys with a carbon content of less than 2.11% are called steel. 384: What is high carbon steel? answer: Steel with a carbon content greater than 0.6% is called high carbon steel. 385: How many categories can steel be divided into based on its uses? answer: It can be divided into structural steel, tool steel and special purpose steel. 386: How many categories can steel be divided into according to its end face shape? answer: It can be divided into plates, pipes, profiles and wires. 387: What are the two basic methods for correcting steel deformation? answer: There are cold work correction and heating correction. 388: What is an assembly fixture? answer: Refers to the process equipment used to apply external force to parts during the assembly process to achieve reliable positioning. 389: What are the basic methods of cold work correction? answer: There are manual correction and mechanical correction. 390: What are the categories of heating correction? answer: It is divided into full heating correction and partial heating correction. 391: What are the shapes of local heating correction heating zones? answer: There are three types: dotted, linear and triangular. 392: What are the types of angle steel deformations? answer: There are three types: twisting, bending, and angular deformation. 393: What are the deformations of channel steel? answer: There are twists, bends, and local deformations of the wing panels. 394: What is cold correction? answer: Correction performed at room temperature is called cold correction. 395: What steps does separation include? answer: It includes three processes: blanking, punching and cutting. 396: What is stamping? answer: The process of separating or shaping sheet metal to obtain parts. 397: What are the advantages of stamping? answer: The product has good quality, high productivity, saves materials, reduces costs, and is easy to realize automation. 398: What is bending forming? answer: A processing method that bends blanks into desired shapes. 399: What are the three basic forms of riveting? answer: Butt joint, overlap joint, corner joint. 400: What is riveting? answer: Rivets are used to connect two or more components into a whole. 401: How many types of rivets are commonly used? answer: There are semi-circular head, countersunk head, semi-countersunk head, flat head, flat cone head, oblate head and flat head. 402: What are the types of riveting? answer: There are strong riveted tight riveted tight riveted. 403: What is assembly? answer: The various parts are combined into components according to certain technical conditions. 404: What are the three elements of assembly? answer: Positioning, supporting, clamping. 405: What are the methods of connecting metal structures? answer: There are welding, riveting, bolting, riveting and welding hybrid connections. 406: What are the commonly used tools for sample prevention? answer: Pink thread, stone pen, drawing needle, ruler, sample punch, hand hammer. 407: What are the main methods of finding intersecting lines? answer: There are prime line method, auxiliary plane method and spherical method. 408: What are the methods to find the real length of a straight line segment? answer: Rotation method, right triangle method, surface changing method, branch line method. 409: What are the methods of making expanded diagrams? answer: There are drawing methods and calculation methods. 410: What are the commonly used expansion methods? answer: There are parallel line method, radial line method and triangle method. 411: What parts can the material shear section be divided into? answer: Slumped corners, bright strips, shear strips, burrs. 412: What types of corrections are there? answer: Divided into manual correction, mechanical correction and flame correction. 413: What is a benchmark? answer: Points, lines, and surfaces used to determine the positions of other points, lines, and cotton on the part drawing. 414: What is plasticity? answer: The ability of metal materials to permanently deform without being damaged under the action of external forces. 415 ； What is resilience? answer: The ability of metal materials not to be damaged under impact loads. 416: What measures can be taken to prevent welding deformation? answer: Anti-deformation method, rigid fixation method, reasonable welding sequence. 417: What are the characteristics of linear projection in space? answer: Authenticity, accumulation, shrinkage. 418: What is an intersection line? answer: Intersection lines produced by planes cutting a shape. 419: What is an intersecting line? answer: Surface intersection resulting from the intersection of two planes. 420: How many types of views are there? answer: Divided into basic view, partial view, oblique view and rotated view. 421: What is a basic view? answer: The view obtained by projecting the machine part onto the basic projection plane. 422: What are the basic views? answer: Main view, top view, left view, right view, upward view, rear view. 423: What types of cross-sectional views are there? answer: It is divided into full section, half section and partial section. 424: What effect does cutting volume have on drilling? answer: Reasonable selection of cutting amount can prevent premature wear or damage of the drill bit. Prevent machine tools from overloading and improve the cutting accuracy and surface roughness of workpieces. 425: What is tapping? answer: Use a tap to cut internal threads into the hole wall. 426: What effect does the size of the bottom hole diameter have on the working wire? answer: If the diameter of the bottom hole is the same as the diameter of the internal thread, the material will jam the tap when it expands, and the tap will easily break. ； If it is too large, the tapped thread profile will not be high enough and will result in scrap. 427: What is casing? answer: Use a die to cut threads on the outer diameter of the round rod pipe. 428: What principles should be paid attention to when choosing a bevel? answer: (1) Minimize the amount of weld metal filling, (2) Ensure weld penetration and avoid cracks, (3) Consider minimum welding deformation, (4) facilitate processing. 429: What is the purpose of leaving a blunt edge when beveling? answer: Prevent joints from burning through. 430: What are the methods of beveling? answer: Use air shovel processing, mechanical processing, gas cutting and carbon arc gouging. 431: What is carbon arc gouging? answer: The high temperature of the carbon electrode arc is used to partially melt the metal, and at the same time, the flow of compressed air is used to blow off the molten metal to achieve the purpose of planing or cutting the metal. 432: What is grinding used for? answer: It can eliminate burrs on the edge of weld scars on the plate surface, grind the welds, and grind the welds of pressure vessels before re-inspection. 433: What is bending forming? answer: Bend flat blanks, profiles or pipes to a certain angle and curvature to form parts of a certain shape. 434: answer: What is rebound phenomenon? answer: When bending, the material undergoes elastic deformation. When the external force is removed, part of the elastic deformation returns to its original state, causing the shape and angle of the bent part to change. 435: What are the bending and forming methods commonly used by riveters? answer: There are press bending, rolling bending, calendering and water-fire bending plates. 436 ； What are the factors that affect bending forming? answer: Bending force, rebound phenomenon, minimum bending radius, cross-sectional shape. 437: How to determine the magnitude of bending force? answer: According to the mechanical properties of the material to be bent, the bending method and nature, and the shape of the bent piece. 438: What are the factors that affect bending rebound? answer: The mechanical properties of the material being bent, the relative bending radius of the material, the bending angle and some other factors. 439: What are the factors that affect the minimum bending radius? answer: The mechanical properties of the material to be bent, the bending angle, the bending direction of the material, the surface quality and shear surface quality of the material, and other factors. 440: What are the factors that affect the change of cross-sectional shape during bending? answer: Mainly include relative bending radius, cross-sectional geometric characteristics and bending method. 441 What is the impact of steel heating on steel bending? answer: After the steel is heated, the required bending force is reduced, the rebound phenomenon disappears, and the minimum bending radius is reduced, which is conducive to controlling deformation according to processing requirements. 442: Under what circumstances is heated bending usually used? answer: Then use it at room temperature. 443: Why should the heating temperature of steel be limited to a certain temperature? answer: Too high a temperature can easily cause overburning of the steel, while too low a temperature can make molding difficult and cause cold work hardening. 444: When using contact bending, what measures are often used to solve the rebound problem? answer: Correct the mold shape, use the pressure correction method, add a blank holder, and reduce the mold gap. 445: What is bending? answer: A processing method that uses a bending die on a press to perform bending and forming. 446: How many forms of bending deformation are there in materials? answer: There are free bends, contact bends, and corrected bends. 447: Why are the dies used by riveters usually of welded construction? answer: Because this not only facilitates manufacturing, shortens the molding cycle, but also improves material utilization and reduces costs. 448: What is rolling bend? answer: A processing method for bending and forming on a rolling machine. 449: What measures are often used to eliminate the straight edges of the workpiece when using a symmetrical three-roller plate bending machine? answer: Pre-bend both ends and leave machining allowance. 450: What are the two types of calendering? Which one is commonly used by riveters? answer: Divided into non-thinning calendering and thinning calendering. Riveters often use non-thinning calendering. 451: What measures should be taken when rolling a tapered surface? answer: Adjust the position of the upper roller so that it is tilted at a certain angle with the lower roller ； Make the feed speed of the small mouth larger than that of the large mouth. 452: How to roll larger workpieces? answer: In order to avoid additional deformation caused by its own weight, the sheet should be divided into three areas, first roll the two sides, and then roll the middle, with the cooperation of a crane if necessary. 453: Any rolling of non-cylindrical workpieces? answer: Areas should be divided on the sheet according to their different curvature radii, and the spacing between the shafts and rollers should be adjusted for rolling. 454: What preparations are required before rolling the workpiece? answer: The shaft roller and the sheet surface should be cleaned, and burrs should be removed to avoid damaging the workpiece and the shaft roller. 455: What is calendering? answer: A pressing process in which a flat plate blank of a certain shape is formed into an open hollow part through a concave mold under the pressure of a punch. 456: What is a water-fire bending plate? answer: The steel plate is locally heated and shrunk by an oxyacetylene flame to form it. 457: What are the uses of water-fire bending plates? answer: Water-fire bending is only suitable for forming parts with small curvature, and is more often combined with rolling to process parts with complex shapes with double bends. 458: What are the methods of water-fire bending? answer: There are strip heating and spot heating. 459: What are the processes for water-fire bending plates? answer: There are options for grilling nozzles, heating temperature and speed, and cooling methods. 460: How many cooling methods are there for water-fire bending plates? answer: There are two types: air cooling and water cooling. Water cooling can also be divided into front and back water cooling. 461: What is air cooling? answer: After local heating by the flame, the workpiece is naturally cooled in the air. 462: What is water cooling? answer: Water is used to force-cool the heated part of the metal, causing it to cool rapidly, reducing heat transfer to the back, expanding the temperature difference between the front and back, and improving the molding effect. 463: What are the characteristics of explosive forming? answer: Can simplify the mold structure ； Can process hollow parts with complex shapes that are difficult to process with rigid molds ； Small rebound, high precision and good quality ； Fast processing and forming speed ； No stamping equipment is required. 464: What is a corner connection? answer: When two plates are connected perpendicular to each other at an angle, angle steel is used as the connecting piece to rivet the workpieces together. 465: What are the main parameters for rivet arrangement? answer: There are rivet spacing, row spacing, and margin spacing. 466: What is rivet distance? answer: The distance between the centers of two adjacent rivets in a row of rivets. 467: What is spacing? answer: Refers to the distance between the centers of two adjacent rows of rivet holes. 468: What is margin? answer: Refers to the distance from the center of the outer row of rivets to the edge of the workpiece plate. 469: What is the relationship between component plate thickness and rivet diameter? answer: When single-row and double-row overlap connections are made, the rivet diameter shall be twice the thickness ； When connecting single row and double row double cover plates, the rivet diameter should be 1.5~1.75 of the plate thickness. 470: What are the principles for determining plate thickness? answer: When overlapping, determine according to the thickness of the thicker sheet material ； When riveting materials with large thickness differences, the thinner sheet should be used to determine ； When riveting steel plates and profiles, take the average thickness of the two ； The total thickness of the connection should not exceed 5 times the rivet diameter. 471: What is the relationship between rivet length and riveting quality? answer: If the rivet is too long, the rivet head will be too large and the rivet stem will bend easily. ； If the rivet is too short, the thickness of the pier will be insufficient and the nail head will be incompletely formed, which will affect the strength and tightness of the riveting. 472: How to determine rivet hole diameter during cold riveting? answer: During cold riveting, the nail rod is not easy to be thickened. To ensure the connection strength, the diameter of the nail hole should be close to the diameter of the nail rod. 473: When hot riveting, is the rivet hole diameter determined? answer: During hot riveting, due to thermal expansion and thickening, the diameter of the nail hole should be slightly larger than the diameter of the nail shank to facilitate perforation. 474: What parts does a rivet consist of? answer: It consists of handle, gun body, switch and pipe joint. 475: What are the characteristics of a rivet gun? answer: It is small in size and easy to operate, and can be riveted in various positions. 476: What are the two methods of riveting? answer: It can be divided into cold riveting and hot riveting. 477: What is cold riveting? answer: It is riveting at room temperature. 478: What is the final riveting temperature for riveting? answer: Between 450~600 degrees Celsius.