Mechanical Knowledge Question Bank (3)

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201: What does plate thickness treatment include? Answer: Determine the neutral layer of the bent part and eliminate thickness interference. 202: What factors are related to the change in the position of the neutral layer in plate thickness? Answer: It is related to the bending radius of the sheet and the thickness of the material. 203: What are the general principles for dealing with plate thickness in interpenetrating parts? Answer: The unfolded length is based on the dimension of the member’s neutral axis, while the height of the curve in the unfolded diagram corresponds to the height at the point where the members meet. 204: What is the main content of lofting? Answer: Plate thickness processing, lofting drawing, and creating cutting templates based on the lofted drawings of the components already made. 205 What are the common shearing tools used by riveters? Answer: There are gantry shears, bevel shear machines, disc shears, and combined punching-and-shearing machines. 206: How can roll formers be classified based on the number of shaft rollers and their arrangement? Answer: They are divided into three types: symmetrical three-roller, asymmetrical three-roller, and four-roller. 207: How can punching dies be classified according to their structure? Answer: They are divided into simple molds, molds with guide pillars, and composite molds. 208: What are the structural features of a compound punching die? A male and female die that serves both as a blanking punch and as a punching die. 209: What is blanking force? Answer: It refers to the maximum resistance of the material to the die during blanking. 210: What is rebound? Answer: In the bending process, the phenomenon of the material returning to its original shape due to elasticity after the external force is removed is called springback. 211: What is stretching? Answer: A stamping process method that uses a press and corresponding dies to transform sheet metal into open hollow parts. 212: What is the strain coefficient? Answer: The ratio of the cross-sectional area of the material after each stretch to its original end area before stretching is called the stretch coefficient for that stretch. The stretch coefficient actually reflects the degree of deformation of the stretched part. 213: What is a flanging ring? Answer: During the stretching process, a circular compressing device is installed at the edge between the male and female dies to prevent wrinkling in the edge area of the workpiece due to instability. 214: What is the working principle of a friction press? Answer: The working principle of a friction press is as follows: it utilizes the contact between the flywheel and the friction disc for power transmission, and it operates based on the principle of relative movement between the screw and the nut. 215: What are the advantages of friction presses? Answer: It operates quickly, allowing the slider to stop at any position within its range of motion. In the event of overload, it only causes sliding between the flywheel and the friction disc, without damaging the components. 216: What are the advantages of the stamping process? Answer: (1) High production efficiency. One stroke of the press can complete one processing step, and sometimes multiple steps as well. (2) High material utilization rate. (3) The shapes and dimensions of the stamped parts of the same product are consistent, ensuring good interchangeability. (4) It is simple to operate, facilitating mechanized and automated production. 217: How many major categories are there in stamping processes? Answer: (1) Separation process (2) Forming process (3) Laminating process. 218: What is blanking? Answer: A stamping method in which a die is used to separate a sheet metal on a press. 219: How to distinguish punching from blanking? Answer: Under normal circumstances, after blanking, the sheet metal is divided into two parts, namely the trimmed part and the part with the hole. If the purpose of blanking is to produce a workpiece with a specific shape, where the material that is removed corresponds to what is needed, this is called blanking. On the other hand, if the purpose of blanking is to create an internal hole of a certain shape, and the material that is removed is waste material, then this is called punching. 220: During blanking, into which stages is the separation of the material divided? Answer: Elastic deformation, plastic deformation, cracking and separation. 221: How many methods are there to reduce blanking force? Answer: There are three types: (1) oblique edge blanking, (2) stepped punch blanking, (3) heated blanking. 222: What is the minimum bending radius? Answer: The minimum limit value of the bending radius at which a material does not fail during bending is called the minimum bending radius. 223: What are the external forces that cause deformation in structural members? Answer: These include bending force, torque, impact force, pulling force, pressure, etc. 224: What can external forces cause to occur inside a component? When the external force is removed, some internal forces may remain. What is formed? Answer: External forces can induce internal forces within a component; when these external forces are removed, internal stresses are generated. 225: What kind of process is welding for metal structural components, and what other aspects does it involve? What is the main cause that leads to deformation in components? Answer: It is a process of uneven heating and cooling; it is the main cause of internal stresses in components, leading to deformation. 226: In which directions does the contraction of welds and the metal surrounding them occur primarily? Answer: It is mainly manifested as contraction in both vertical and horizontal directions. 227: What are the factors related to design that may cause deformation of structural components? Answer: There is structural rationality, the position of the welds, the type of welding groove, etc. 228: What are the factors related to manufacturing processes that may cause deformation of structural components? Answer: Welding procedure specifications, welding sequence, deformation prevention measures, etc. 229: What are the prerequisites for completing correction work with both quality and quantity ensured? Answer: The prerequisite is: making the correct judgment and selecting the appropriate correction location. 230: When analyzing the causes of component deformation, it is necessary to determine what is responsible for that deformation Answer: It is necessary to determine whether the deformation is caused by external forces or by internal stresses. 231: What are the three types of deformation in I-beams? Answer: There is arch deformation, lateral bending, and corner deformation. 232: What are the two types of deformation in box girders? Answer: There is arch deformation and twisting. 233: When two types of deformation occur simultaneously in a box girder, what is the primary contradiction? In what order should corrections be carried out? Answer: Distortion is the main contradiction. It should be carried out in the order of twisting first and then arch deformation. 234: What is internal force? Answer: When an object deforms under the action of an external force, a force that resists this deformation arises within it; this force is called an internal force. 235: What is stress? Answer: When an object is subjected to external forces, the internal force that appears per unit cross-sectional area is called stress. 236: What is internal stress? Answer: When no external force is applied, the stress existing within an object is called internal stress. 237: What is local deformation? Answer: When a certain part of a component deforms, it is called local deformation. 238: What is overall deformation? Answer: When the shape and size of the entire component change, it is called overall deformation. 239: What is shrinkage deformation? Answer: One of the basic forms of deformation refers to the shortening and deformation that occurs in an object after it is heated and then cooled. 240: What is distortion? Answer: One of the basic forms of deformation is when the length of an object remains unchanged, but its straightness exceeds the allowable tolerance. 241: What is angular deformation? Answer: One of the basic forms of deformation is angular deformation, which occurs when the angles between the components of an object change and exceed the allowable tolerances. 242: What is the correction site? Answer: The location where corrective measures are applied to address steel structure deformation is not necessarily the same as the area where deformation occurs in the component. 243: What are steel structural components? Answer: Multiple components are joined together through welding, riveting, bolted connections, or other methods; these components are interrelated and interdependent, forming an integrated whole, which is commonly referred to as a steel structural member. 244: What are the causes of deformation in steel structural members? Answer: There are two reasons: (1) deformation caused by external forces, and (2) deformation caused by internal stresses. 245: What are the basic forms of welding deformation? Answer: Longitudinal and transverse shrinkage deformation, bending deformation, torsional deformation, 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 to various frames, and are constrained by those frames. 247: The degree of deformation of the cross-section when a pipe is bent depends on the values of the relative bending radius and relative wall thickness, right? Answer: Yes. 248: When a pipe is bent, the greater the relative bending radius and relative wall thickness, the greater the deformation, right? Answer: No. 249: If the curvature of the bent pipe is not sufficient but is fairly close to what’s needed, can the curvature be increased by cooling the outside of the pipe with water, thereby causing the metal on the inside to contract? Is that correct? Answer: No. 250: Currently, when bending pipes on site under normal conditions, where the requirement for the ellipticity of the bent section is not very strict, coreless bending is often used without the installation of any counter-deformation device, right? Answer: No. 251: Are pipe benders classified into mechanical transmission and gear transmission types based on their drive mechanism? Answer: No. 252: There are two travel switches on the pipe bender; by adjusting the position of the stops, the desired bending length can be controlled, right? Answer: Yes. 253: The hydraulic pipe bender is characterized by smooth and reliable operation, low noise, a compact design, and the ability to bend different types of pipe blanks, right? Answer: No. 254: Is the method of bending or shaping a blank by using a rotating axis called roll bending? Answer: Right? 255: The advantage of roll bending is its versatility. When bending sheet metal, it is generally necessary to add other processing devices to the rolling machine, right? Answer: Yes. 256: In order to remove the cylinder workpiece that has been bent, both ends of the supporting part of the upper shaft are movable, allowing the workpiece to be taken out, right? Answer: No. 257: During the bending process, it is advisable to use templates for inspection; the curvature should not be made too small, right? Answer: No. 258: What are the methods of bending forming? Answer: There are press bending, tension bending, folding, and manual bending, etc. 259: During the bending process, by adjusting what on the upper and lower rollers, it is possible to bend the blank into any curvature that is less than the curvature of the upper roller. Answer: It’s sufficient to adjust the relative position of the upper and lower rollers. 260: Into which two main categories are rolling mills divided? Answer: There are two main categories: discrete and horizontal. 261: Horizontal rolling mills come in three-axis and four-axis types; what are the two types of three-axis mills? Answer: There are two types: symmetrical and asymmetrical. 262: For a symmetrical three-axis rolling machine, what shape are the cores of its three rollers? Answer: It becomes an isosceles triangle. 263: When rolling materials in a cylindrical roller, how should the distance between the roller shafts be adjusted so that the centers of the shafts are aligned? Answer: It is essential to keep the centers of the rollers parallel to each other; otherwise, it will cause the workpiece to develop a taper. 264: When a pipe bends, what force acts on the material outside the neutral layer, causing the pipe wall to thin? What force acts on the inner material, causing the wall of the tube to thicken? Answer: Tensile stress causes the wall thickness to decrease, while compressive stress causes it to increase. 265: When a pipe bends, due to its circular cross-section which results in insufficient stiffness, what happens easily when it bends in a free state? Answer: It is prone to flattening deformation. 266: What are the main processes in manual pipe bending? Answer: The main processes include filling with sand, marking lines, heating, and bending. 267: When bending a seamned pipe billet, where should the pipe seam be located as much as possible? Answer: Central layer. 268: What tests must be carried out on the bent part of a elbow to check for any abnormalities? Answer: A pressure test must be carried out to check for any leaks. 269: How does an asymmetric three-roller rolling machine eliminate straight ends at the start? Answer: For an asymmetric three-axis rolling machine, the workpiece produced has straight ends only at its starting point; by turning the workpiece around after the first round of rolling and rolling it again, the straight ends on both sides can be eliminated. 270: What is the anti-deformation method? Answer: It means that before the tube blank enters the bending deformation zone, a certain amount of deformation is applied in advance to make the outer side of the tube wall bulge, thereby compensating for or reducing the deformation of the cross-section during bending. 271: What assembly method is generally used when assembling T-beams in small batches or as individual units? Answer: Assembly is done by marking and fitting. 272: What assembly methods are generally used when assembling T-beams and I-beams to further increase the assembly speed? Answer: Assembly is done using molds. 273: Does the longitudinal contraction of a weld decrease as the length of the weld increases? Answer: No. 274: The railing of a bridge crane has a truss structure, and its camber is the same as that of the main beam, right? Answer: Yes. 275: Box girders, bridges, and decks also need to have a certain degree of camber; the camber in their middle section should be greater than the allowable deflection of the girder, right? Answer: No. 276: Due to the self-weight of the bridge deck and welding deformations, should the precast camber of the box girder’s web be greater than that of the main girder? Answer: Yes. 277: When the steel plate is thin and the weld is located in the middle of the plate, what kind of deformation usually occurs after welding? Answer: Wave deformation occurs. 278: When the welded piece itself is unable to overcome what effect of the weld, does it cause deformation of the welded structure? Answer: When the weldment itself is unable to counteract the contraction of the weld, it leads to deformation of the welded structure. 279: What are the methods for preventing and reducing welding deformation? Answer: There are the counter-deformation method, proper selection of welding sequence, rigid fixation method, and hammering the weld method. . 　280: What makes it a parallel line to that projection plane? What properties does the projection of this line have? Answer: When a line is parallel to a projection plane, it is called a line parallel to that projection plane. The projection of this line is genuine. 281: Any metal sheet has a thickness, and how does this sheet thickness affect the shape and size of the diagrams produced? Answer: It does affect the shape and size of the developed diagram. 282: How are the surfaces of spherical, toroidal, and helical elements developed? Answer: Their surfaces are all non-developable surfaces. 283: What unfolding method is generally used for the development of prisms and cylinders? Answer: Generally, the parallel line expansion method is used. 284: When a conical tube and a cylindrical tube intersect orthogonally, what method is commonly used to determine their intersection line? Answer: It is commonly obtained using the auxiliary plane method. 285: Which method is commonly used to find the actual length of a curve? Answer: Use the expansion method more often. 286: When a friction press is overloaded, what does it cause to slide against what, without damaging the components? Answer: It will only cause sliding between the flywheel and the friction disc, without damaging any components. 287: The stroke of the slider in an open-crank press can be adjusted by changing what and what? Answer: It can be done by changing the eccentric sleeve on the upper part of the connecting rod ； It is adjusted by the center distance of the spindles. 288: In drawing and extrusion processes, due to the die clearance, what are the strict requirements regarding the material? Answer: The tolerance requirements for the material thickness are quite strict. 289: Into which three roughly distinct stages can the separation process of sheet metal during blanking be divided? Answer: 1: Elastic deformation, 2: Plastic deformation, 3: Cracking and separation. 290: How does the drawing coefficient affect the degree of deformation of the material during drawing? Answer: The smaller the drawing coefficient, the greater the degree of deformation of the material during drawing. 291: What is cold stamping? Answer: Stamping operations carried out at room temperature are called cold stamping. 292: What is a compound process? Answer: Combining two or more basic processes and completing them within one stroke of the press is called a compound process. 293: What is a simple blanking die? Answer: In one stroke of the press, only a die for one blanking operation can be used. 294: What is a compound punching die? Answer: A die that can simultaneously complete multiple stamping operations in one stroke of the press. 295: How to explain the blanking force correction coefficient Kp? Answer: When calculating the blanking force, factors such as the wear of the die edges, die clearance, and the mechanical properties of the material are taken into account. The safety factor selected is generally set to Kp equal to 13.296. What is oblique-edge blanking? Answer: Diagonal cutting is a method to reduce the blanking force. It involves making the die edge inclined at a certain angle relative to the blank, so that during punching, the contact between the die edge and the blank occurs gradually, resulting in a uniform and steady load. 297: What is stepped punch blanking? Answer: Stepped punch blanking is a method to reduce the blanking force. During porous simultaneous blanking, the punch is designed in a stepped shape that varies in height relative to the blank, which helps to effectively distribute the blanking force. 298: What is the difference between open crank press and closed crank press? Answer: Structurally, the bed of an open-crank press has a C-shaped design, and connecting rods are used to convert the rotational motion of the eccentric shaft into up-and-down reciprocating motion of the slider. The bed of a closed-type press has a frame-shaped structure, with a crank replacing the eccentric shaft. 299: What are the characteristics of open-crank presses and closed-crank presses? Answer: The C-shaped bed of an open-type crank press has three open sides, making it particularly suitable for stamping the edges of large sheets of metal. However, this type of bed structure has relatively poor rigidity, and therefore can withstand only a small load. The frame structure of closed-type crank press is constrained by the columns, resulting in a limited worktable area and limited operating space; therefore, there are certain restrictions on the dimensional dimensions of the stamped parts. Frame-type structural beds have good stiffness, and can withstand large and uniform loads. 300: What are the factors that affect material stamping? Answer: Yes. These include (1) elasticity, (2) plasticity, (3) hardness, (4) the quality of the material’s surface condition, and (5) the thickness tolerance of the material. 301: What is the impact of die clearance on blanking quality? Answer: When the gap between the punch and die is too small, the cracks in the material near the punch edge shift outward by a certain distance. As a result, the material in the area between the upper and lower cracks is affected by a second shear action during the stamping process, which impacts the quality of the cut surface. When the gap is too large, the cracks in the material near the punch edge shift inward by a certain distance; the material is subjected to significant stretching. Moreover, burrs, collapsed corners, and large slopes at the material edges also affect the quality of the cross-section of the stamped part. Furthermore, either too small or too large a gap has a certain impact on the dimensional tolerance of the cut parts. 302: What are the factors that affect the minimum bending radius of materials? Answer: 1: The mechanical properties of the material and its heat treatment condition; 2: The bending angle of the workpiece; 3: The geometric shape and dimensions of the material; 4: The direction of bending; 5: Other factors such as the thickness of the material and the quality of its surface and sides. 303: How is the neutral layer of the material defined when it is bent? Answer: During bending, the outer layer of the material is under tension while the inner layer is under compression. In its cross-section, there must be a transition layer that is neither under tension nor under compression, with stress nearly equal to zero; this transition layer is known as the neutral layer of the material. 304: When correcting components made up of multiple beams and columns, what interrelationships need to be fully considered? Answer: The interrelationship between beams and columns must be fully considered. 305: What must be ensured to meet the requirements when correcting the deformation of thin plates in steel structures? Answer: It is necessary to ensure that all types of frames meet the requirements before considering straightening the thin plates. 306: What is the heating point of spot heating related to in the sheet material? What should be the distance between the heating points? Answer: The heating point of spot heating is related to the thickness of the sheet. The distance between the heating points should be uniform. 307: What is called longitudinal contraction? Answer: A form of contraction of the weld and the metal surrounding it; the contraction along the length of the weld is known as longitudinal contraction. 308: What is called lateral contraction? Answer: A form of contraction of the weld and the metal surrounding it, referring to the contraction perpendicular to the length of the weld, is known as transverse contraction. 309: How are internal stresses generated in steel structural members? Answer: For riveted and welded structures, the welding process is a process of uneven heating and cooling, which is the main cause of internal stresses in such structural components. Furthermore, the various components of steel structures may have residual stresses either in their raw state or after being processed into components; once these components are welded together, these residual stresses can combine to form new internal stresses within the structure. 310: Why is stress relief treatment required for some steel structural components after welding? Answer: After welding some steel structural components, they exhibit little welding deformation due to their high stiffness, but the welding stresses are quite significant. After the structures have been in use for a while, these stresses may be released for some reason, causing deformation that can lead to damage. Therefore, for steel structures used in certain critical applications, such as high-pressure vessels, containers for hazardous materials, and boilers, various stress-relief methods are employed after welding, with the aim of preventing the internal stresses in the steel components from causing damage to them. 311: What are the factors that affect welding deformation in steel structural members? Answer: The factors affecting the welding deformation of steel structural members include design and process aspects. In terms of design, this refers to the rationality of the structural design, the location of welds, and the shape of welding grooves, etc. In terms of processes, this refers to reasonable welding procedure specifications, the sequence of assembly and welding, the use of various methods to prevent and counter deformation, as well as the stress-relief measures taken. 312: How to understand the internal relationships of steel structural components? Answer: So-called steel structural components are formed by joining various parts together using methods such as welding, riveting, or bolting. These parts are interconnected and interdependent, forming an organic whole. 313: What are the key points for correcting the deformation of steel structural members? Answer: 1: Analyze the causes of component deformation to determine whether it is caused by external forces or internal stresses. 2: Examine the internal relationships within the component to understand the constraints between its various parts. 3: Select the appropriate location for correction, addressing the main issues first before dealing with the secondary ones. 4: It is necessary to understand and know the properties of the steel used in the component, in order to prevent breakage, cracks, or springback during the correction process. 5: Determine the correction method based on the actual situation, as well as the sequence in which multiple methods are used. 314: What is the only method that can be used to correct deformation in thin plates in steel structures? Answer: To correct deformation in thin plates within steel structures, only local heating (and specifically point heating) can be employed. 315: What aspects should be considered when using spot heating to correct thin plate deformation? Answer: It should be noted that: 1. The heating temperature must be appropriate – it should be high enough to cause plastic deformation in the steel, but not too high; generally, it ranges from 650 to 800 degrees. 2: The size of the heating points and the distance between them should be appropriate. Under normal circumstances, depending on the thickness of the sheet material, the arrangement should be even, often in a plum-blossom pattern. 3: The purpose of rapid cooling by watering and hammering with a wooden mallet is to accelerate the contraction of the fiber structure in the steel plate. 4: When heating, do not move the gas welding torch back and forth; the small flame beam should be perpendicular to the steel plate, and avoid using too many heating points to prevent unnecessary internal stress. 316: What are the characteristics of deformation in framed structural members? Answer: Frame-type components have many parts, and there are strong inter-restrictive relationships within their structure, resulting in significant mutual influences on deformation. 317: When using a bending machine to bend round blanks, it is generally done after heating, right? Answer: No. 318: To what temperature should the material be heated during heating bending? How should heating be done at the same time? How do I operate it? What is the minimum ending temperature? Answer: The material should be heated to 950-1100. The heating should be even at the same time, with the final temperature not falling below 700. 319: What are the possible defects that can occur when rolling curved cylinders? Answer: Defects that may occur when rolling curved cylinders include warping, uneven curvature, excessive curvature, and bulging in the middle. 320: When rolling a cone, by adjusting the position of the center of the upper shaft in such a way that the axis of the roller shaft always coincides with the generatrix of the fan-shaped blank, can a cone be formed? Answer: Adjust it to an inclined position. 321: When rolling a cone, which edge of the blank increases friction? What should be made to move in at a slower speed than what? Answer: Increase the friction at the small opening of the blank, so that the speed at which the small opening moves in is lower than the speed at which the large opening moves in. 322: There are many types of shafts for core bent pipes, including round-headed, pointed, hooked, and what other types? Answer: Like single-direction joint type, universal type, etc. 323: Coreless bending involves the use of no mandrel; what process is employed on a bending machine to control the deformation that occurs during bending? Answer: It is a method that uses the reverse deformation process on a pipe bending machine to control the deformation of the pipe bend cross-section. 324: When is a coreless bending process generally used, namely when the bending radius of a bent pipe is greater than what multiple of its diameter? Answer: Greater than 1. 5 times. 325: Extrusion bending of pipes involves utilizing the plasticity of metal; at room temperature, the pipe blank is pressed into a mold with certain shapes to form a pipe elbow Answer: The pipe billet is pressed into a mold with a bend to form a pipe elbow. 326: When extruding bent pipes, in addition to the torque exerted by the bending force, what other force acts on the pipe blank, as well as what force in the opposite direction to the axial force? Answer: It is also subjected to axial forces and frictional forces in the direction opposite to the axial force. 327: Briefly describe the process of bending blanks using a rolling machine? Answer: During rolling, the blank is placed between the rolls of the rolling machine. Due to the rotation of the rolls, and through the friction between the upper and lower rolls and the blank, the blank moves, thereby continuously forming a bend. 328: What are the advantages of a four-axis rolling machine? Answer: The advantage of a four-axis rolling machine is that it allows both ends of the sheet metal to be rolled, thereby eliminating straight edges at those ends. It simplifies the manufacturing process compared to a three-axis rolling machine, reduces the amount of work required, and improves production efficiency. 329: What are the methods for rolling cones? Answer: It can be divided into methods such as segmented rolling, rectangular feeding, rotary feeding, and reduced-speed small-opening methods. 330: How to reduce the ellipticity of the cross-section when bending pipes? Answer: When bending pipes, in order to reduce the ellipticity of their cross-section, it is common in the production process to use fillers inside the pipe, or to apply pressure from rollers with conical grooves on the outside of the pipe, or to insert a mandrel into the interior of the pipe for bending. 331: What are the advantages of spoon-shaped mandrels? Answer: The spoon-shaped mandrel has a larger contact area with the outer wall surface, which provides better protection against flattening; the surface is less likely to wrinkle when the tube bends. Additionally, it is easier to manufacture a spoon-shaped mandrel, which is why it is widely used. 332: What are the advantages of coreless bent pipes over cored bent pipes? Answer: (1) It reduces the need for extensive preparatory work such as preparing cores before bending, thereby improving production efficiency. (2) It eliminates the need to manufacture mandrels, reducing costs. (3) Lubrication is not required inside the tube, saving lubricant and the oil injection process. (4) It ensures the quality of the bent pipes. (5) There is no friction between the mandrel and the tube wall, which reduces the torque required during bending, thereby extending the service life of the pipe bending machine. 333: How does a mechanically driven pipe bender transmit power? Answer: A mechanically-driven pipe bender is one in which an electric motor, via a gear shaft and a reduction mechanism as well as worm gear transmission, drives the pipe bending die to rotate. 334: When fitting the circumferential seams of the connected cylinders on the roller frame, the lateral distance and vertical position of each pair of rollers must not be identical; only in this way can the cylinders be concentric during assembly, right? Answer ； No. 335 ； If there is a difference in the diameters of the two cylinder sections, should the cylinder section with the larger diameter be raised during assembly so that the two sections are concentric? Answer: No. 336: The greater the linear expansion coefficient of the weld material, the greater the shrinkage of the weld after welding, right? Answer: Yes. 337: The post-weld shrinkage of carbon steel is greater than that of stainless steel and aluminum, right? Answer: No. 338: When using the hammering of welds to prevent deformation in multi-layer welding, should hammering be applied to the first layer and the last layer as well? Answer: No. 339: Using a rigid fixation method generates significant internal stresses in the weld area; therefore, this method is suitable for medium-carbon steel and alloy steel, right? Answer: No. 340: What are the common methods used to seal the longitudinal seams of cylinders in order to improve assembly efficiency? Answer: Levers and screw tensioners are commonly used to improve efficiency. 341: What is commonly used to adjust the ellipticity of thin-walled cylinders? Answer: A radial pusher is used. 342: When elongated cylindrical sections are butted together, what is used for assembly to ensure that the whole structure does not bend? Answer: Using a roller-type jig for assembly ensures that the whole structure does not bend. 343: When welding butt circular girth joints in an upright position, what clamping and alignment methods for the girth joints can yield good results while also ensuring the desired gap? Answer: Using wedge clamps to clamp and align the ring seam yields good results, as well as allowing for the desired gap to be achieved. 344: What is used for positioning when welding circular ring seams in a standing seam configuration? What will be used for clamping in the end? Answer: Use a stop iron for positioning. Finally, clamp it with a conical wedge. 345: What are the main components of a rivet gun? Answer: It is mainly composed of a handle, gun body, trigger, pipe fittings, etc. 346: Before cold riveting, in order to eliminate hardening and improve the plasticity of the material, how must the rivet be treated? Answer: Annealing treatment must be carried out. 347: What are core pull rivets made of? Answer: It is composed of a hollow rivet and a mandrel. 348: What is formed in the weld area after the weld has cooled? And what force is generated within the weld? Answer: After the weld cools, contraction occurs in the weld area, resulting in internal stresses within the weld. 349: During multi-layer welding, the first layer causes the greatest contraction; what is the contraction amount of the second layer, as a percentage of that of the first layer? Is the third layer about a few percent of the first layer? Answer: (1) Twenty percent. (2) Five to ten percent. 350: What is the typical camber of the main girder in a bridge crane? Answer: One in a thousand. 351: What are the three components of a bridge crane? Answer: Cable tray, operating mechanism, load carrier. 352: What does the main beam of a box girder structure consist of? Answer: It consists of an upper cover plate, a lower cover plate, web plates, and long and short stiffening plates. 353: For the web flatness of the main girder in a box girder structure, what is the maximum peak value allowed per meter of length in the compressed zone? What is the tensile zone? Answer: 0.7t for the compressed zone; 1.2t for the tensile zone. 354: How much margin is required when cutting the web of box girders? At what distance from the center must there be no joints? Answer: A margin of 0.15% is required: there must be no joints at a distance of two meters from the center. 355: Depending on their use and requirements, steel roof trusses come in a variety of types and shapes. What are the common types of roof trusses? Answer: There are triangles, trapezoids, spheres, grid-shaped roof trusses, etc. 356: What is the typical height of a triangular roof truss in relation to its span? Answer: It’s one-quarter to one-fifth. 78: What is the height of a trapezoidal roof truss in relation to its span? Answer: It is from one-sixth to one-twelfth. 357: What methods are commonly used for assembling steel roof trusses? Answer: The profiling method is commonly used for assembly. 358: What is cold riveting? Answer: Riveting rivets at room temperature is called cold riveting. 359: What is riveting? Answer: Pull riveting is another type of riveting method besides cold riveting. It uses manual force or compressed air as power, and specialized tools to fasten rivets to the components being riveted together. 360: What is hot riveting? Answer: Riveting after heating the rivet is called hot riveting. 361: What is the anti-deformation method? Answer: By analyzing the direction and magnitude of deformation that may occur in the welded joint after welding, it is necessary to induce deformations of equal magnitude but in opposite directions in the parts to be welded before welding. This helps to offset or compensate for the deformation that occurs after welding, thereby achieving the goal of preventing such deformation. This method is known as the counter-deformation method. 362: What is rigid fixation? Answer: The method of using assembly fixtures or temporary supports to fix the relative positions of the welded parts in order to prevent deformation after welding is called rigid fixation. 363: A lofting drawing is a diagram created based on the construction drawings, right? Answer: No. 364: In addition to planes, developable surfaces also include cylinders and cones, right? Answer: Yes. 365: Are all the lines on the developed view the actual lengths of the corresponding parts on the surface of the component, right? Answer: Yes. 366: If one of the three projections of a line segment has an accumulative property, then the other two projections must be truthful, that is, they must reflect the actual length of the line segment, right? Answer: No. 367: If the two orthogonal projections of a line segment are both perpendicular to the projection axis between them, then the third projection must reflect the actual length of that line segment, right? Answer: No. 368: The projection of a straight line is always a straight line; there are no other possibilities, right? Answer: No. 369: In the three-view projection, a line in an ordinary position sometimes shows its true length and sometimes does not, right? Answer: Yes. 370: For the actual length of a line in an arbitrary position, it’s best to use the rotation method, right? Answer: No. 371: The methods for finding the actual length of a line segment are the parallel lines method, the triangle method, and the radial lines method, right? Answer: No. 372: In the production of riveters or sheet metal workers, methods such as the right triangle method, rotation method, face transformation method, and branch line method are commonly used to draw development drawings, right? Answer: Yes. 373: When developing a shape using the triangular method, the key is to determine the actual length of each element line, right? Answer: No. 374: Does a planar curve show its true length in all three views? Answer: No. 375: Prisms, cylinders, and cylindrical surfaces can all be developed using the parallel lines method, right? Answer: Yes. 376: Is the triangular development method applicable to the development of shapes whose generatrices intersect at a single point on all component surfaces? Answer: No. 377: When using the auxiliary surface method to find the intersection line, the axes of the rotating bodies must be parallel and their actual lengths must be considered, right? Answer: No. 378: What are the common presses used by riveters? Answer: There are hydraulic presses and pneumatic presses. 379: What is the impact of the final riveting temperature on riveting? Answer: Too high, and it will reduce the initial stress of the pin rod ； Too low, and the rivets will suffer from blue brittleness. 380: What is the function of the shank of a drill bit? Answer: It clamps and transmits the torque and axial force required for drilling. 381: What are the common types of hammers used by riveters? Answer: There are hand hammers, sledge hammers, and claw hammers. 382: What are the common types of chisels used by riveters? Answer: There are two main categories: flat chisels and narrow chisels. 383: What is steel? Answer: An iron-carbon alloy with a carbon content of less than 2.11% is called steel. 384: What is high-carbon steel? Answer: Steel with a carbon content of more than 0.6% is called high-carbon steel. 385: Into how many categories can steel be divided based on its use? Answer: It can be divided into structural steel, tool steel, and special-purpose steel. 386: Into how many categories can steel be divided based on the shape of its end face? Answer: It can be divided into sheets, pipes, profiles, and wires. 387: What are the two basic methods for correcting the deformation of steel? Answer: There is cold working correction and heating correction. 388: What is a mounting fixture? Answer: It refers to the process equipment used during assembly to apply external forces to components in order to achieve a reliable positioning of them. 389: How many categories are there for the basic methods of cold working correction? Answer: There are manual correction and mechanical correction. 390: What are the categories of heat correction? Answer: It is divided into full heating correction and local heating correction. 391: How many ways are there to correct the shape of the heating area using local heating? Answer: There are three types: dot-shaped, line-shaped, and triangular. 392: What are the types of deformation in angle steel? Answer: There are three types: distortion, bending, and corner deformation. 393: What are the types of deformation in channel steel? Answer: There is warping, bending, and local deformation of the wing panels. 394: What is cold working correction? Answer: Correction carried out at room temperature is called cold working correction. 395: What processes are included in separation? Answer: It includes three processes: blanking, punching, and cutting. 396: What is stamping? Answer: The process of obtaining a finished part by separating or shaping sheet metal. 397: What are the advantages of stamping? Answer: Good product quality, high productivity, material savings, cost reduction, and easy automation. 398: What is bending forming? Answer: A processing method for bending the blank into the desired shape. 399: What are the three basic forms of riveting? Answer: Butt joint, lap joint, corner joint. 400: What is riveting? Answer: Rivets are used to connect two or more components into a single unit. 401: How many types of rivets are commonly used? Answer: There are half-round head, countersunk head, semi-countersunk head, flat head, flat tapered head, oval, and flat. 402: What are the types of riveting? Answer: There are strong riveting, secure riveting, and tight riveting. 403: What is assembly? Answer: The process of combining various parts into components according to certain technical requirements. 404: What are the three elements of assembly? Answer: Positioning, support, clamping. 405: What are the various methods of connecting metal structures? Answer: There are welding, riveting, bolt connection, and hybrid riveted-welded connections. 406: What are the common tools used for sample prevention? Answer: Powder line, stone pencil, drawing needle, ruler, template punch, hammer. 407: What are the main methods for finding the intersection line? Answer: There are the straight line method, the auxiliary plane method, and the spherical surface method. 408: What are the methods for finding the actual length of a straight line segment? Answer: Rotation method, right triangle method, face transformation method, branch line method. 409: What are the methods for creating an exploded view? Answer: There are graphical methods and computational methods. 410: What are the common expansion methods? Answer: There are the parallel lines method, the radiation method, and the triangle method. 411: Into which parts can the cross-section of a cut material be divided? Answer: Chipped corners, bright bands, cleavage zones, burrs. 412: What are the types of corrections? Answer: There are manual correction, mechanical correction, and flame correction. 413: What is a benchmark? Answer: The points, lines, and surfaces on a part diagram used to determine the position of other points, lines, and surfaces. 414: What is plasticity? Answer: The ability of metal materials to undergo permanent deformation without breaking under external forces. 415 ； What is resilience? Answer: The ability of metal materials to resist destruction under impact loads. 416: What measures can be taken to prevent welding deformation? Answer: Anti-deformation method, rigid fixation method, proper welding sequence. 417: What are the properties of spatial linear projection? Answer: Authenticity, accumulability, contractility. 418: What is an intersection line? Answer: The intersection lines formed by a plane intersecting a solid figure. 419: What is an intersection line? Answer: The line of intersection of surfaces formed by the intersection of two planes. 420: How many types of views are there? Answer: They include basic views, partial views, inclined views, and rotated views. 421: What is a basic view? Answer: The view obtained by projecting the machine parts onto the basic projection plane. 422: What are the basic views? Answer: Front view, top view, left view, right view, rear view, back view. 423: What are the different types of sectional views? Answer: There are full sectioning, half-sectioning, and partial sectioning. 424: What is the impact of cutting parameters on drilling? Answer: Choosing appropriate cutting parameters can prevent the drill bit from wearing out prematurely or being damaged. Prevents machine tool overload and improves the cutting accuracy and surface roughness of workpieces. 425: What is tapping? Answer: A tap is used to cut internal threads on the wall of the hole. 426: What is the impact of the bottom hole diameter on the tap? Answer: If the diameter of the bottom hole is the same as that of the internal thread, the tap will get stuck as the material expands, and in such cases the tap is prone to breaking ； If it is too large, the height of the thread profile formed will be insufficient, resulting in defective products. 427: What is thread tapping? Answer: Use a die to cut threads on the outer diameter of a round rod tube. 428: What principles should be considered when selecting a groove? Answer: (1) Minimize the amount of weld metal filler, (2) Ensure full penetration and avoid crack formation, (3) Consider minimizing welding deformation, (4) Facilitate machining. 429: What is the purpose of leaving a bevel edge when cutting grooves? Answer: To prevent the joint from burning through. 430: What are the methods for grooving? Answer: Machining with a air chisel, mechanical processing, gas cutting for grooving, and carbon arc gouging for grooving. 431: What is carbon arc gas gouging? Answer: The high temperature of the carbon electrode arc is used to melt a local area of the metal, and then a stream of compressed air is used to blow away this melted metal, thereby achieving the purpose of planing or cutting the metal. 432: What is the use of grinding? Answer: It can remove burrs at the edges of weld scars on the plate surface, grind welds, and perform grinding before re-inspecting the welds of pressure vessels. 433: What is bending forming? Answer: Bend flat sheet blanks, profiles, or tubes at a certain angle and with a specific curvature to form parts of a particular shape. 434: Answer: What is the rebound phenomenon? Answer: When bent, the material undergoes elastic deformation; once the external force is removed, part of this elastic deformation is reversed, causing changes in the shape and angle of the bent piece. 435: What are the common bending methods used by riveters? Answer: There are press bending, roll bending, rolling, and hydrothermal bending of plates. 436 ； What are the factors that affect bending forming? Answer: Bending force, springback phenomenon, minimum bending radius, cross-sectional shape. 437: How to determine the magnitude of the bending force? Answer: Depending on the mechanical properties of the material to be bent, the bending method and type, as well as the shape of the bent part. 438: What are the factors that affect the elastic recovery of bending? 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 being bent, the bending angle, the direction in which the material is bent, the surface quality of the material and the quality of the cut surface, as well as other factors. 440: What are the factors that affect the change in cross-sectional shape during bending? Answer: The main factors are the relative bending radius, the geometric characteristics of the cross-section, and the bending method. What is the impact of heating 441 steel on its bending processing? Answer: When steel is heated, the bending force required decreases, the springback phenomenon disappears, and the minimum bending radius shrinks, which facilitates controlling deformation according to processing requirements. 442: Under what circumstances is heating bending typically used? Answer: Use it at room temperature again. 443: Why must the heating temperature of steel be limited to a certain level? Answer: Excessively high temperatures can cause the steel to overheat, while too low temperatures make shaping difficult and lead to cold work hardening. 444: What measures are commonly used to address the springback issue when contact bending is employed? Answer: Modify the mold shape, use pressure correction methods, add a blank holder, and reduce the mold gap. 445: What is bending? Answer: A processing method that uses bending dies on a press for bending formation. 446: What are the various forms of bending deformation of materials? Answer: There are free bending, contact bending, and corrective bending. 447: Why are the dies used by riveters usually of welded construction? Answer: Because this not only makes manufacturing easier and reduces the mold-making cycle, but also improves material utilization and lowers costs. 448: What is roll bending? Answer: A processing method for bending and shaping on a rolling bed. 449: What measures are commonly used with symmetric three-roll plate rolling machines to eliminate straight edges on the workpiece? Answer: Bend at both ends and leave machining allowance. 450: Into which two types can rolling be divided? Which one do riveters use commonly? Answer: There are non-thinning calendering and thinning calendering. Riveters commonly use non-thinning rolling. 451: What measures should be taken when rolling conical surfaces? Answer: Adjust the position of the upper roller so that it is tilted at a certain angle relative to the lower roller ； Make the feed speed for small openings greater than that for large openings. 452: How to roll larger workpieces? Answer: To avoid additional deformation caused by its own weight, the sheet metal should be divided into three sections; roll the two sides first, then the middle, with the assistance of a crane if necessary. 453: Any rolling for non-cylindrical workpieces? Answer: Areas on the sheet metal should be divided according to their different radii of curvature, and the spacing between the rollers should be adjusted for rolling. 454: What preparations are needed before rolling the workpiece? Answer: The surface of the rollers and the sheet metal should be cleaned thoroughly, and burrs should be removed to avoid damaging the workpiece or the rollers. 455: What is calendering? Answer: It is a pressing process in which a flat blank of a certain shape is deformed under the pressure of a punch to form an open hollow part through a die. 456: What is a water-fire bent plate? Answer: It is formed by locally heating the steel plate with an oxy-acetylene flame to cause it to contract. 457: What are the uses of water and fire bent plates? Answer: Water and fire bending is only suitable for shaping parts with low curvature; it is more often used in combination with rolling to process parts with complex shapes that involve double bending. 458: What are the methods for bending plates in water and fire? Answer: There is strip heating and spot heating. 459: What are the processes for bending plates in water and fire? Answer: There are options for the heating element, heating temperature and speed, as well as the cooling method. 460: How many cooling methods are there for water and fire bending plates? Answer: There are two types, air-cooled and water-cooled; among water-cooled types, there is further distinction between front-and-back water cooling. 461: What is air cooling? Answer: After local heating by the flame, the workpiece cools naturally in the air. 462: What is water cooling? Answer: Forcing cooling of the heated part of the metal with water allows it to cool down rapidly, reducing heat transfer to the back side and increasing the temperature difference between the two sides, thereby improving the shaping effect. 463: What are the characteristics of explosive forming? Answer: It can simplify the mold structure ； Hollow parts with complex shapes that are difficult to manufacture using rigid molds ； Low rebound, high precision, excellent quality ； Fast processing and shaping speed ； No stamping equipment is required. 464: What is corner jointing? Answer: When two plates are connected at an angle to each other, angle steel is used as a connecting element at the joint 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 pitch? Answer: The distance between the centers of two adjacent rivets in a row of rivets. 467: What is pitch? Answer: It refers to the distance between the centers of adjacent rows of rivet holes. 468: What is a margin? Answer: It refers to the distance from the center of the outward-facing rivet to the edge of the workpiece plate. 469: What is the relationship between the thickness of the component plate and the diameter of the rivet? Answer: For single-row and double-row lap joints, the rivet diameter is taken as twice the thickness ； When connecting single-row and double-row double covers, the rivet diameter should be 1.5 to 1.75 times the plate thickness. 470: What are the principles for determining plate thickness? Answer: When overlapping, it is determined based on the thickness of the thicker plate ； When riveting materials with significant differences in thickness, the thinner sheet shall determine the parameters ； When riveting steel plates and profiles together, use the average thickness of the two ； The total thickness of the joined parts should not exceed 5 times the diameter of the rivet. 471: What is the relationship between rivet length and riveting quality? Answer: If the rivet is too long, its head becomes too large, making the shank prone to bending ； If the rivet is too short, the amount of bulging will be insufficient, and the head of the rivet will not be properly formed, which affects the strength and tightness of the riveting. 472: How is the rivet hole diameter determined during cold riveting? Answer: During cold riveting, it is difficult for the rivet shank to become thicker; to ensure connection strength, the diameter of the rivet hole should be close to that of the rivet shank. 473: When performing hot riveting, how is the rivet hole diameter determined? Answer: During hot riveting, the material expands and thickens due to heat; to facilitate piercing, the diameter of the rivet hole should be slightly larger than the diameter of the rivet shank. 474: What components does a rivet consist of? Answer: It consists of a handle, gun body, switch, and pipe fitting. 475: What are the features of a rivet gun? Answer: It has a small volume, is easy to operate, and can be used for riveting in various positions. 476: Into which two types can riveting be divided? Answer: It can be divided into cold riveting and hot riveting. 477: What is cold riveting? Answer: It refers to riveting at room temperature. 478: What is the final riveting temperature? Answer: Between 450 and 600 degrees Celsius.