Q&A on Basic Mechanical Processing Knowledge

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1. The main forms of metal structures include: frame structures, container structures, box structures, and general component structures. 2. Stamping operations can be classified according to the nature of the process into: material preparation, pattern making, shaping, and assembly and connection. 3. The connection methods for metal structures include: riveting, welding, hybrid riveting and welding, and bolt connection. 4. In the machinery manufacturing industry, riveters belong to the heat processing category. 5. Hot working: Metal materials are shaped by heating them entirely or partially. 6. A frame structure is a structure manufactured with (profiled materials) as its main component. 7. The container structure is a structure manufactured with (sheet metal) as the main material. 8. The box structure and the general structure are both structures manufactured by combining (sheet materials) and (profiled materials). 9. Material preparation refers to the preparation of (raw materials) and (part blanks). 10. Steel plates and profiles may become deformed during (transportation, lifting, storage). 11. The deformation of steel can affect the proper progress of processes such as lifting, cutting, and oxygen cutting of parts. 12. If the deformation that occurs to parts during processing is not corrected, it will affect the proper assembly of the structure. 13. The deformation caused by welding reduces the (accuracy) of assembly, generates additional stresses within the steel structure, and affects the (strength of the components). 14. The deformations of flat steel include bending, torsion, and combined bending-torsion deformation. 15. Multi-roller straightening machines can be classified into parallel upper and lower roller row straightening machines and inclined upper and lower roller straightening machines, based on the arrangement of the shaft rollers and the positioning of the adjustment rollers. 16. The heating methods for flame correction include point, line, and triangular heating. 17. The effect of flame correction is determined by (the location of heating and the heating temperature). 18. The correction methods include: mechanical correction, manual correction, flame correction, and high-frequency heat bending. 19. Lofting and marking are the first steps in manufacturing metal structures. 20. Lofting and marking: These factors have a direct impact on both the production cycle and costs, as well as on the quality of the product. 21. Common measuring tools used for lofting include: wooden rulers, straightedges, steel tape measures, and steel ruler strips. 22. Common tools used for lofting include compasses, square sets, pattern punches, marking needles, and small hammers. 23. The procedures for true-size lofting are: linear lofting, structural lofting, and development lofting. 24. The contents of the layout demonstration include: plate thickness treatment, layout drawing, and production of pattern templates. 25. Templates are classified by their purpose into: material sampling templates, fit-checking templates, and positioning templates. 26. Thin iron sheets with a thickness of 0.5–2 millimeters are generally used to make prototypes. 27. The main methods for drawing patterns and templates include: the straight-line pattern drawing method and the transition pattern drawing method. 28. How to use materials reasonably? Answer: Concentrate scheduling and make use of leftover materials. 29. Curves are divided into planar curves and spatial curves. 30. Methods for finding the actual length of a straight line segment include: the rotation method, the right triangle method, the branch line method, and the plane transformation method. 31. The steps for developing a pattern are: first, use geometric drawing to draw the intersection lines, actual length lines, and cross-sectional shapes, and then create the developed pattern. 32. The basic methods for finding the intersection line of a plane and a solid are: the edge-line method and the edge-face method. 33. The basic methods for finding the solid intersection line of a surface are: the meridian method and the parallel method. 34. The main methods for finding the intersection line are: the auxiliary plane method, the generatrix method, and the spherical method. 35. What are the characteristics of intersection lines? Answer: (1) The intersection line is the common line and boundary line of two intersecting shapes. (2) Since the shape has a certain extent, the intersection line is always closed. 36. Intersection line: The line formed by the intersection of a cutting plane and the surface of a solid. 37. Element line: Any position of the bus bar on the surface of a component is called an element line. 38. Common expansion methods include: the parallel line method, the radial line method, and the triangle method. 39. The common methods for dividing a sphere include: zonal division, block division, and petal division. 40. The main aspects of plate thickness treatment are: determining the neutral layer of the bent part and eliminating plate thickness interference. 41. The material length for bent angle steel members is calculated based on the (center of gravity layer). 42. Shearing machines for cutting straight lines include: gantry slant-cutting shears, crossbeam slant-cutting shears, and combined punching and shearing machines. 43. Machine tools with shear curves include disc shears and vibratory shears. 44. What are the characteristics of a vibrating shear machine? Answer: Vibration shear machines can cut various curves and internal holes. 45. The combined shearing and punching machine is composed of (bevel shear, section steel shear, and small punch). 46. Analyze the transmission sequence of the shear machine as follows: prime mover → transmission element → workpiece. 47. The front and rear guards of the Longmen shear machine serve a positioning function. 48. On gantry or slanting shear machines, positioning shearing includes: sheet positioning shearing, back plate positioning shearing, and guard plate positioning shearing. 49. The shear force exerted by a miter shear on the material can be broken down into: shear force, horizontal tensile force, and separation force. 50. Shearing machinery: Not suitable for shearing alloy materials and quenched materials. 51. The cutting oxygen pressure should be selected based on: workpiece thickness, nozzle diameter of the torch, and oxygen purity. 52. The ignition temperature of ordinary carbon steel in oxygen is: 1100–1150°C. 53. Metal materials that meet the conditions for gas cutting include pure iron, low-carbon steel, medium-carbon steel, and ordinary low-alloy steel. 54. The process of oxy-cutting is: preheating of the metal, combustion of the metal, and blowing away of the oxides. 55. What is the function of a round file? What are its components? Answer: It is a tool used for machining external threads, consisting of a cutting part, a positioning part, and chip removal holes. 56. What does the shape of the groove depend on? Answer: The type and thickness of the material, the welding method, and the mechanical properties of the product. 57. Grinding: The process of machining the surface of a workpiece using a grinding wheel is called grinding. 58. The main grinding tools include: pneumatic grinders and electric grinders. 59. What kind of deformation occurs in steel during bending processing? Answer: Elastic deformation and plastic deformation will occur. 60. The common bending methods used by riveters include: cold bending, hot bending, manual bending, and mechanical bending. 61. The bending deformations of materials during press bending include free bending, contact bending, and corrective bending. 62. The change in the shape of the material’s cross-section during bending is related to: the relative bending radius, the geometric characteristics of the cross-section, and the method of bending. 63. The methods to prevent the blank from shifting during bending are: a supporting device and positioning holes. 64. Rolling bending machines include: rolling plate machines and section steel rolling bending machines. 65. The main steps in manual pipe bending are: marking, sand filling, and heating for bending. 66. The connection methods for metal structures include riveting, threading, and welding. 67. When selecting a joining method, factors such as the strength of the components, the operating environment, the materials, and the construction conditions must be taken into account. 68. The joint forms for riveting include butting and corner lap joints. 69. The shapes of solid rivet heads include: half-round head, countersunk head, and semi-countersunk head. 70. The main types of AC arc welders are the BX1--330 type and the BX--500 type. 71. The basic procedure for hot riveting is: securing the parts to be riveted, drilling holes, heating the rivets, inserting and passing the rivets, pushing the rivets in, and performing the riveting. 72. The types of riveting include: strong riveting, tight riveting, and secure riveting. 73. The tool used for drilling holes is a reamer. 74. Common anti-loosening measures for threaded connections include increasing friction and mechanical anti-loosening methods. 75. The welding arc consists of an anode region, a cathode region, and an arc column. 76. Welding machines mainly include: DC welding machines and AC welding machines. 77. Local deformation: refers to the deformation that occurs in a certain part of a component, including angular deformation, wavy deformation, and local unevenness. 78. Welding is classified by spatial position into flat welding, vertical welding, horizontal welding, and overhead welding. 79. During welding, in which three directions does the welding rod move? Answer: Moving in the direction of the molten pool, moving along the welding direction, and swinging laterally. 80. The three elements of assembly are: positioning, supporting, and clamping. 81. Manual clamps include: screw clamps, wedge clamps, lever clamps, and eccentric clamps. 82. Non-manual clamps include pneumatic clamps, hydraulic clamps, and magnetic clamps. 83. Screw clamps have functions such as clamping, pressing, pushing, and supporting. 84. Common measurement items used in assembly include: linear dimensions, parallelism, perpendicularity, coaxiality, and angles. 85. The support methods for workpieces during assembly are: support on an assembly platform and support using an assembly jig. 86. According to their function, mounting jigs can be divided into general-purpose jigs and special-purpose jigs. 97. Common positioning methods used in assembly include: marking for positioning, template positioning, and positioning with positioning elements. 88. The basic methods for finding the intersection line of planes are: the edge-face method and the edge-line method. 89. Hot riveting usually involves four people – what are their roles? Answer: One person is responsible for heating and transferring heat, another for driving and passing the nails, another for holding the nails in place, and yet another for riveting them. 90. What is the purpose of the flat tail in a cone-shaped drill bit? Answer: It is used to increase the torque transmitted, preventing the drill bit from breaking out in the spindle hole or drill sleeve. 91. What is the function of the guiding portion in the drill bit? Answer: It maintains the drill bit’s straight cutting direction during the cutting process. It serves both to smooth the wall of the hole and as a backup for the cutting portion. 92. What adverse phenomena occur when a hole is about to be drilled through? Answer: When the drill bit just penetrates the workpiece, the axial resistance suddenly decreases. Due to the sudden recovery of the clearance and elastic deformation in the drilling machine’s feed mechanism, the drill bit will automatically advance at a large rate, which can lead to the breakage of the drill bit or a decrease in the quality of the drilled hole. 93. What is the role of cutting fluid during drilling? Answer: It reduces friction, lowers drill bit resistance and cutting temperature, thereby improving the cutting capacity of the drill bit as well as the surface quality of the hole walls. 94. Cutting parameters: refers to the combination of cutting speed, feed rate, and depth of cut. 95. Grinding: It is a method of processing the surface of a workpiece using an abrasive wheel. 96. Unfolding: The process of laying out the surface or a part of a metal structure on a flat surface according to its actual shape and size is called unfolding. 97. The methods for drawing exploded diagrams include: the parallel line method, the triangle method, and the radial line method. 98. The condition for applying the parallel line method is that the generatrices on the surface of the component are parallel to each other and reflect their true lengths in the projection plane. 99. Plate thickness treatment includes: determining the neutral layer of the bent part and eliminating plate thickness interference. 100. The change in the position of the neutral layer thickness is related to: the bending radius of the sheet and the thickness of the material. 101. The general principle for dealing with the plate thickness of intersecting members is: the developed length shall be based on the dimension of the neutral layer of the member, and the curve height in the developed diagram shall be based on the height at the point where the members meet. 102. The main contents of lofting are: plate thickness treatment, drafting, and preparing cutting templates based on the drafted drawings of the components. 103. The common shearing equipment used by riveters includes: gantry shears, slant-edge shears, disc shears, and combined punching-shearing machines. 104. Sheet rolling machines can be classified into three types based on the number and arrangement of the rollers: symmetrical three-roller, asymmetrical three-roller, and four-roller types. 105. Punching dies can be classified by structure into: simple dies, dies with guide pillars, and compound dies. 106. The structural feature of a compound blanking die is that it has a punch and die pair that functions both as a blanking punch and as a punching die. 107. Blanking force: refers to the maximum resistance exerted by the material on the die during blanking. 108. The deformation process of sheet metal separation during blanking can be divided into: the elastic deformation stage, the plastic deformation stage, and the shear stage. 109. Minimum bending radius: The smallest radius at which a material can be bent without suffering damage. 110. Common methods to reduce the springback of press-bent parts include the die correction method and the pressure correction method. 111. The purpose of using a flanging ring during drawing is to prevent wrinkling at the edges of the drawn part. 112. What is the function of the crank-slider mechanism in a crank press? Answer: It can not only convert rotational motion into reciprocating linear motion, but also act as a force amplifier. 113. Manual forming in sheet metalworking includes: bending, cambering, flanging, curling, butting, and straightening. 114. Development templates can be used for marking dimensions, manufacturing separation molds, and producing milling templates. 115. Flanging: The process of stretching and thinning the edge material of the deformed area during the shaping process is called flanging. The formation methods include thinning and drawing. 116. Edge bending: Using edge bending and trimming methods to process the edges of sheet metal into curved components. 117. Trimming: Curling the edges of a workpiece to increase its edge stiffness and strength is called trimming. 118. Butt joint: When the edges of two sheet metals or the two sides of a single sheet metal are folded together and pressed against each other, it is called a butt joint. 119. Plate thickness treatment: Methods adopted to eliminate the influence of plate thickness on the shape and size of the developed drawing. 120. The general steps for calculating the developed length of a bent part are: dividing the bent part into straight segments and arc segments ； Calculate the length of each segment separately ； Add up the calculated lengths. 121. Under what circumstances should cut-to-length processing be used for shaped steel? Answer: Angle steel, channel steel, and I-beam are bent into corners. 122. The entire blanking process is divided into: the elastic deformation stage ； Plastic deformation stage ； Shearing stage. 123. Blanking: A stamping process in which a die is used to separate one part of a sheet metal from another along a specific closed line. 124. Bolted connections: There are two types: those that withstand axial tensile loads ； Connection subjected to lateral forces. 125. Measures to prevent loosening in bolted connections include: increasing friction ； Mechanical lockout. 126. Mechanical anti-loosening methods include: split pins ； Retaining washer ； Stop washer ； Series-wound steel wire. 127. Welding arc: A strong and sustained discharge phenomenon that occurs in the gaseous medium between two electrodes. 128. The welding arc consists of: the cathode region ； It consists of an anode region and an arc column. 129. What are the three directions of movement for welding rods? Answer: Move in the direction of the molten pool ； Move in the welding direction ； Make a lateral swing. 130. Welds can be classified by spatial position into: flat welding, vertical welding, horizontal welding, and overhead welding. 131. What are the properties of intersection lines? Answer: It is both a common line on the surfaces of the two shapes and a boundary line ； In space, it is always closed. 132. Intersection line: A component formed by the intersection of two or more geometric solids. 133. The factors affecting blanking quality are: die clearance ； The center lines of the punch and die do not coincide ； The working edge of the mold is worn and blunted. 134. The general principle of mold design is to strive for molds that are easy to manufacture, have simple processes and low costs, as well as are convenient to use, all while ensuring good stamping quality. 135. The purpose of calculating the rolling force is to properly select the rolling equipment. 16. Free bending: When the bending is complete and the punch, the blank, and the die fit together, no impact force is generated any longer. 137. Correction of bending: It refers to an additional impact applied after the punch, the blank, and the die are aligned with each other, thereby correcting the bent part. 138. What defects are likely to occur when pressing head covers? Answer: Wrinkling and bulging ； Straight-edge scratch indentation ； Microcracks on the outer surface ； Longitudinal tear ； skew ； ellipse ； The diameters vary. 139. Swaging: A joining method that achieves sealing and fastening by deforming the tube and the tube sheet. 140. The purpose of calculating the blanking force is to reasonably select the equipment capacity and design the die. 141. What methods can be used to reduce punching force? Answer: Bevel die ； Step die ； Heat the die. 142. The purpose of calculating bending forces is to select the bending press and design the mold. 143. What does the degree of deformation include? Answer: Degree of mold adhesion ； The degree of deformation allowed for material drawing. 144. How to determine the number of drawing passes for a workpiece? Answer: Based on the maximum deformation of the workpiece being pulled and the elongation rate of the material. 145. How is the drawing coefficient determined? Answer: It depends on the properties of the material, the drawing angle, the friction coefficient, and whether drawing is performed in advance. 146. Brittle materials such as high-carbon steel, high-alloy steel, and cast iron are not suitable for cold working. 147. When angle steel experiences complex deformation, the sequence for straightening it is: first correct the twisting, then the bending, and finally the angular deformation. 148. Causes of deformation in steel structures: one is caused by external forces, and the other is caused by internal stresses. 149. Methods to eliminate residual welding stresses include: overall high-temperature tempering ； Local high-temperature tempering ； temperature difference stretching method ； Mechanical stretching method ； Vibration method. 150. Welding overall deformation: refers to the changes in the shape and size of the entire structure. 151. Hammer spreading method: Extending the fiber structure of metal sheets by hammering. 152. Rivet shank length: It is determined based on factors such as the total thickness of the components to be joined, the gap between the rivet hole and the shank diameter, and the riveting process. 153. The reason for an excessively small rivet head after riveting is a short shank or an oversized hole diameter. 154. Depending on the state of the metal during welding, it can be divided into fusion welding, pressure welding, and brazing. 155. Fusion welding: A method that uses local heating to bring the weld joint to a molten state. 156. Clamping: It involves using external force to fix the parts once they have been positioned, so that their position remains unchanged during the processing stage. 157. Six-point positioning rule: Six positioning points are used to restrict the freedom of a part in space, thereby determining its exact spatial position. 158. Relative parallelism: refers to the degree of parallelism between the line or surface being measured on a part and the reference line or surface used for measurement. 159. Relative perpendicularity: refers to the degree of perpendicularity of the line or surface being measured on a part, with respect to the reference line or surface for measurement. 160. The tools used in assembly include: assembly tools ； Assembly fixture ； Assemble the lifting fixture. 161. Commonly used lifting tools include steel wires, chains, hand chain hoists, and specialized lifting equipment. 162. How many types of guidance are there for blanking dies? Answer: There are two types: guide posts, guide sleeves, and guide plates. 163. How many parts does a blanking die consist of? Answer: It consists of a working section, a material positioning section, a unloading section, and a mold base. 164. What is the function of the drawing die clearance? Answer: Reduce the friction between the material and the die, and control the flow of the material within the die cavity. 165. Joint gaps can be classified by their structure into: vertical single joint gap ； Vertical double-groove ； Horizontal flat joint seams and various angled joint seams. 166. What is the reason why a bent part rebounds after the external force is removed? Answer: It is because when bending manually, the outer surface of the sheet is under tension while the inner surface is under compression, which results in springback. 167. Cold camber is achieved by expanding the middle of the sheet while contracting its edges, while hot camber is obtained by heating the sheet to cause it to contract. 198. There are two methods for stripping the edge: one is to use general tools, and the other is to use a die. 169. Edge finishing: In edge finishing, the sheet metal is first wrinkled, and then the wrinkled area is flattened while preventing it from stretching back; as a result, the length of the sheet metal decreases and its thickness increases. 170. The basic principle of edge finishing is that, for workpieces with convex curved edges, the forming process involves the contraction of the material on the outer edge of the flat edges, resulting in thickening and shortening, which forces the vertical edges to take on a curved shape. 171. The purpose of correction is to shorten longer fibers and lengthen shorter fibers by applying external force or local heating, thereby bringing the fibers in each layer into alignment to achieve the goal of correction. 172. The principle of flame correction is to use the deformation resulting from local heating of the metal to counteract the original deformation, thereby achieving correction. 173. Factors that affect the effectiveness of flame correction include: the stiffness of the workpiece ； Heating position ； Flame heat ； Heating area and cooling method. 174. The heating methods for flame correction include spot, line, and triangular heating. 175. The factors that determine the process allowance include: the influence of lofting errors ； The impact of errors during part processing ； Impact of assembly errors ； Impact of welding deformation ； The impact of flame correction. 176. Molds can be classified by their purpose into: material sampling molds, shaping molds, positioning molds, and sample bars. 177. The methods of pattern drawing include direct pattern drawing and transitional pattern drawing. 178. How are lofting baseline lines generally selected? Answer: With two lines or planes that are perpendicular to each other ； Using the two center lines as reference lines ； Using a plane and a center line as a reference. 179. Allowable lofting error: During the lofting process, due to factors such as the precision of the lofting tools and equipment as well as the skill level of the operator, certain dimensional deviations may occur in the resulting model. Controlling such deviations within a specified range is what is referred to as the allowable lofting error. 180. Structural lofting includes: determining the joining positions of various components and the forms of connection ； Make the necessary adjustments based on the actual production capabilities ； Calculate or measure the length of the parts and the actual shape of planar parts ； Design jigs or fixtures. 181. Methods for finding the actual length of a line segment include: the rotation method ； Right triangle method ； Face-changing method ； Branch method. 182. What are the drawing rules for determining the actual length of a line segment using the right triangle method? Answer: It uses the projection of the line segment on any given projection plane as one leg of the right triangle, and the length of the projection of the same line segment onto the axis perpendicular to that plane as the other leg; the hypotenuse is then the actual length of the line segment. 183. Determining the actual length by rotation: This involves rotating a point at a general position in space around a fixed axis until it becomes parallel to a certain line; the projection of this line on the plane parallel to it reflects the actual length. 184. Methods for finding the actual length of a curve include: the surface transformation method ； Expansion method. 185. The face-changing method: This involves establishing a new projection plane parallel to the curve, so that the projection of the curve on this plane reflects its true length. 186. Unfolding method: It involves straightening a length in one curve view while keeping the height in another view unchanged; the resulting unfolding line is what is sought. 187. The basic characteristic of an intersection curve is that it must be a planar figure enclosed by closed straight lines or curves ； The intersection line is the common line between the cutting plane and the surface of the solid; it is formed by the set of points that are simultaneously on the cutting plane and on the surface of the solid. 188. Methods for finding the intersection line of solids include: the edge-face method ； Edge line method. 189. The methods for finding the solid intersection lines of a surface of revolution are: the generatrix method and the meridian method. 190. What are the characteristics of intersection lines? Answer: First, it is the line common to the surfaces of the two intersecting shapes, and it also serves as the boundary between them ； Second, the intersection lines are all closed. 191. The essence of finding the intersection line is to identify a certain number of common points on the surfaces of the two solids, and then connecting these common points in sequence to obtain the desired line. 192. The principle for selecting a method to find the intersection line is as follows: when using the element line method to determine the intersection line, at least one projection of the intersection line must be known ； When using the auxiliary plane method to find the intersection line of intersecting solids, the resulting intersection should be the simplest geometric shape ； The spherical method is only applicable to the intersection of solid bodies with intersecting axes. 193. Under what conditions is the intersection line a planar curve? Is the front projection of the curve two intersecting lines? Answer: When two arbitrary solids that are tangent to the same sphere intersect, their line of intersection is a planar curve. In this case, if the axes of both solids are parallel to their corresponding principal projection planes, then the projection of the line of intersection on those planes is formed by two intersecting lines. 196: A ruled surface is a surface that is formed using straight lines as its generatrices. 197: What are the characteristics of a cylinder? Answer: Yes, all the filaments are parallel to each other ； When a cylindrical surface is cut by mutually parallel planes, the cross-sectional shapes are identical. 198: What are the characteristics of a conical surface? Answer: Yes, all the prime threads intersect at one point ； When a conical surface is cut by mutually parallel planes, their cross-sectional shapes are similar ； The intersection line passing through the apex of the cone is a triangle. 199: During drawing, the plastic deformation process of the material involves: bending of the material ； The material is deformed by stretching ； Additional pull. 200: Drawing: It is a forming method in which the sheet metal is subjected to tensile forces, resulting in plastic deformation along an ideal surface while overcoming springback. 201. Plate thickness treatment includes: determining the neutral layer of the bent part and eliminating plate thickness interference. 202. The change in the position of the thickness neutral layer is related to the bending radius of the sheet and its thickness. 203. The general principle for dealing with the plate thickness of intersecting members is: the development length shall be based on the dimension of the neutral layer of the member, and the curve height in the development diagram shall be based on the height at the point where the members meet. 204. The main aspects of lofting include: plate thickness treatment, drafting, and preparing cutting templates based on the drafted drawings of the components. 205. The common shearing equipment used by riveters includes: gantry shears, bevel shear machines, disc shear machines, and combined punching-shearing machines. 206. Sheet rolling machines can be classified into three types based on the number and arrangement of the rolls: symmetrical three-roller, asymmetrical three-roller, and four-roller types. 207. Punching dies can be classified by structure into: simple dies, dies with guide pillars, and compound dies. 208. The structural feature of a compound punching die is that it has a punch and die combination that serves both as the blanking punch and as the punching die. 209. Blanking force: refers to the maximum resistance exerted by the material on the die during blanking. 210. Springback: In the bending process, the phenomenon of the material returning to its original shape due to elasticity after an external force is removed is called springback. 211. Drawing: A stamping process method that uses a press and corresponding dies to convert sheet metal into open hollow parts. 212. Strain coefficient: The ratio of the cross-sectional area of a material after each stretch to its original end area is known as the strain coefficient for that stretch. The stretch coefficient actually reflects the degree of deformation of the stretched part. 213. Flanging ring: A circular compressing device placed at the edge between the die and punch during the stretching process to prevent wrinkling in the edge area of the workpiece due to instability. 214. The working principle of a friction press is: it utilizes the contact between the flywheel and the friction disc for power transmission, and 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. Stamping processes are divided into: separation processes, forming processes, and bonding processes. 218. Blanking: A stamping method that uses dies to separate 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 part that is cut off is what is needed, this is called blanking. Conversely, if the purpose of blanking is to create an internal hole of a certain shape, and the material that is cut off is waste material, this is called punching. 220. During blanking, into which stages is the material separation process divided? Answer: Elastic deformation, plastic deformation, cracking and separation. 221. Methods to reduce blanking force include oblique-edge blanking, stepped punch blanking, and heated blanking. 222. Minimum bending radius: The minimum limit value of the bending radius at which a material can be bent without suffering damage is called the minimum bending radius. 223. The external forces that cause deformation in structural members include: bending force, torsional force, impact force, tensile force, compressive force, etc. 224. What can external forces cause 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 the welding process for metal structural components? 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. Factors that may cause deformation of structural members in terms of design include: the rationality of the structure, the location of welds, and the type of welding groove, etc. 228. Factors that may cause deformation of structural components in terms of processing include: welding procedure specifications, welding sequence, and deformation prevention measures. 229. The prerequisite for completing correction work with both quality and quantity ensured is correct judgment and the proper selection of the 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. The deformations of I-beams include arching, lateral bending, and angular deformation. 232. The deformations of box girders include arching 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. Internal force: A force that arises within an object as a resistance to deformation, occurring simultaneously when the object is deformed under the action of external forces; this force is known as an internal force. 235. Stress: The internal force that appears per unit cross-sectional area in a body when it is subjected to an external force is called stress. 236. Internal stress: The stress present within an object when no external forces are applied is called internal stress. 237. Local deformation: Deformation that occurs in a certain part of a component is called local deformation. 238. Global deformation: A change in the shape and size of the entire component is referred to as global deformation. 239. Shrinkage deformation: One of the basic forms of deformation, referring to the reduction in size of an object as a result of heating and cooling. 240. Twisted deformation: One of the basic forms of deformation, in which the length of an object remains unchanged, but its straightness exceeds the allowable tolerance. 241. Angular deformation: One of the basic forms of deformation, it refers to a change in the angle formed between the components of an object that exceeds the allowable tolerance. 242. Correction site: The location where corrective measures are applied to correct the deformation of a steel structure; sometimes, this site is not necessarily the area where deformation occurs in the component. 243. Steel structural members: Various 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 steel structural members. 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. The basic forms of welding deformation include longitudinal and transverse contraction deformation, bending deformation, torsional 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 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. 248. When a pipe is bent, the degree of deformation does not increase as the relative bending radius and relative wall thickness increase. 249. If the curvature of the bent pipe is insufficient but still fairly close to what’s needed, can the curvature be increased by cooling the outside of the pipe with water to cause the inner metal 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 methods often do not involve the use of counter-deformation devices, right? Answer: No. 251: Pipe benders are classified into mechanical transmission and gear transmission types based on their drive mechanism, right? Answer: No. 252: The pipe bender is equipped with two travel switches, and the desired bending length is controlled by adjusting the position of the stops. 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: The method of bending or shaping a blank by using a rotating axis is called roll bending. 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. 256: In order to remove the cylinder workpiece after it 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: Bending methods include press bending, draw 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: Rolling mills are divided into two main categories: vertical and horizontal. 261: Horizontal rolling mills come in three-axis and four-axis types; what are the two subtypes 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: The main steps in manual pipe bending are: filling with sand, marking lines, heating, and bending. 267: When bending a grooved pipe billet, where should the pipe seam be located as much as possible? Answer: Central layer. 268: The bent portion of the elbow must undergo a pressure test to check for any leaks. 269: How does an asymmetric three-roller rolling mill 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 roll and rolling it once more, the straight ends at both ends can be eliminated. 270: Anti-deformation method: This involves applying a certain amount of deformation to the tube blank before it enters the bending zone, causing the outer side of the tube wall to bulge out, thereby compensating for or reducing the deformation of the cross-section during bending. 271: When assembling T-beams in small batches or as individual units, marking and assembly is generally adopted. 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 guardrails of bridge cranes have a truss structure, with the same camber as the main beam. 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, the precast camber of the box girder web should be greater than that of the main girder. 277: When the steel plate is thin and the weld is located in the middle of the plate, wave deformation often occurs after welding. 278: When the welded piece itself is unable to counteract the contraction of the weld, it leads to deformation of the welded joint. 279: Methods for preventing and reducing welding deformation include: counter-deformation method, proper selection of welding sequence, rigid fixation method, and hammering the weld seam. 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: A common method for finding the actual length of a curve is the expansion method. 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 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: The separation process of sheet metal during blanking can be roughly divided into: elastic deformation, plastic deformation, and cracking 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: Cold stamping: Stamping operations carried out at room temperature are called cold stamping. 292: Compound process: Combining two or more basic processes together and completing them within one stroke of the press is called a compound process. 293: Simple blanking die: A die that can perform only one blanking operation per stroke of the press. 294: Compound punching die: A punching die that enables the completion of multiple stamping operations in a single 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 Kp = 13.296. Oblique-edge blanking: 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: Stepped punch blanking: A method to reduce 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 press machines and closed-crank press machines? 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 material. However, this type of bed structure has relatively poor rigidity, and thus 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 small operating space; therefore, there are certain limitations on the dimensional dimensions of the stamped parts. Frame-type structural beds have good stiffness, and can withstand large and uniform loads. 300: The factors that affect material stamping include elasticity, plasticity, hardness, the quality of the material’s surface condition, and 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. The 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) Mechanical properties of the material and heat treatment condition; 2) Bending angle of the workpiece; 3) Geometric shape and dimensions of the material; 4) Bending direction; 5) Other factors such as material thickness, and the quality of the surface and sides. 303: The neutral layer of a material during bending is as follows: when the material is bent, the outer layers are under tension while the inner layers are under compression; therefore, there must be a transition layer in its cross-section 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 interconnections need to be fully considered? Answer: The interconnection 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: Longitudinal contraction: A form of contraction of the weld and the metal surrounding it, with contraction occurring along the length of the weld; this is referred to as longitudinal contraction. 308: Transverse contraction: A form of contraction that occurs in the weld and the metal surrounding it; it refers to the contraction perpendicular to the length of the weld, and 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, in the various components of steel structures, residual stresses may exist either in their raw material state or after they have been 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 necessary for some steel structural components after welding? Answer: After welding, some steel structural components exhibit no significant welding deformation due to their high stiffness, but the welding stresses are quite substantial. After being in use for a period of time, these stresses may be released for some reason, resulting in deformation and ultimately leading to failure. 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: Both 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 be familiar with 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: Which method can be used to correct the deformation of thin plates in steel structures? Answer: To correct the deformation of thin plates in steel structures, only local heating (and 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 stresses. 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 influence on deformation. 317: When using a bending machine to bend round blanks, it is usually done after heating, right? Answer: No. 318: When heating for bending, the material should be heated to 950–1100°C. The heating should be even at the same time, with the final temperature not falling below 700°C. 319: Defects that may occur when bending cylinders include warping, uneven curvature, excessive curvature, and bulging in the middle. 320: When rolling a conical shape, 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 billet does friction increase? What should be moved in at a slower speed than what? Answer: Increase the friction at the small edge of the blank, so that the speed at which the small edge moves in is lower than the speed at which the large edge moves in. 322: There are many types of shaft shapes for core bent pipes, including round-headed, pointed, hooked, and what other types? Answer: Compared to single-direction joint types, universal types, 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: More 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 bending tubes by extrusion, in addition to the torque exerted by the bending force, the tube blank is also subjected to an axial force as well as a frictional force in the opposite direction 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 rollers of the rolling machine. Due to the rotation of the rollers, and through the friction between the upper and lower rollers and the blank, the blank moves, thereby continuously forming a bend. 328: The advantages of a four-axis rolling machine are 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: Methods for rolling cones include sectional rolling, rectangular feeding, rotary feeding, and reduced-speed small-mouth 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 to the outside of the pipe with rollers having conical grooves, or to bend the pipe by inserting a mandrel into its interior. 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 is bent. 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 amount of work required for preparing the mandrel before bending, thereby improving production efficiency. (2) It eliminates the need to manufacture a mandrel, thus 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 bender. 333: How is power transmitted in a mechanically-driven pipe bender? Answer: The electric motor drives the bending die to rotate through a gear shaft, a reduction mechanism, and a worm gear drive. 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 aligned concentrically 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 material being welded, the greater the contraction of the weld after welding. 337: Is it true that carbon steel experiences more contraction after welding compared to stainless steel and aluminum? 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? 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 is commonly 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 grooves in an upright position, what clamping and alignment methods for the grooves 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 position? What will be used for clamping in the end? Answer: Position it with a stop iron. Finally, clamp it with a conical wedge. 345: A rivet gun mainly consists of a handle, gun body, trigger, pipe joint, etc. 346: Before cold riveting, in order to eliminate hardening and improve the plasticity of the material, the rivets must be annealed. 347: What are core pulling 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: The camber of the main girder of a bridge crane is generally: one per thousand. 351: What components does a bridge crane consist of? (Girder, driving mechanism, load car) 352: The main beam of the box girder structure 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, and 1.2t for the tensile zone. 354: How much margin is required when cutting the web of the box girder? 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 purpose and requirements, steel roof trusses come in a variety of shapes, including triangular, trapezoidal, spherical, and mesh-shaped trusses. 356: The typical height of a triangular roof truss is 1/4 to 1/5 of the span. 357: Steel roof trusses are usually assembled using the profiling method. 358: Cold riveting: Riveting with rivets at room temperature is called cold riveting. 359: Pull riveting: Pull riveting is another type of riveting method that belongs to cold riveting. It uses manual force or compressed air as power, and specialized tools to fasten rivets to the components being riveted together. 360: Hot riveting: Riveting that involves heating the rivet is called hot riveting. 361: Counter-deformation method: This involves analyzing the direction and magnitude of deformation that may occur in a welded joint after welding. Before welding, the parts to be joined are subjected to deformations of equal magnitude but in opposite directions, in order to offset or compensate for the deformation that occurs after welding and thus prevent such deformation. This method is known as the counter-deformation method. 362: Rigid fixation method: A method that uses assembly fixtures or temporary supports to fix the relative positions of the welded parts, thereby preventing deformation after welding, is called the rigid fixation method. 363: A lofting diagram is a drawing created based on the construction drawings, right? Answer: No. 364: In addition to planes, developable surfaces also include cylinders and cones. 365: All the lines on the developed view are the actual lengths of the corresponding parts on the surface of the component. 366: If one of the three projections of a line segment is convergent, then the other two projections must be real, 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 drawings of a line in an ordinary position, it sometimes shows its true length and sometimes does not. 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 radii 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. 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 line method. 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 intersection lines, the axes of the rotating bodies must be parallel and their actual lengths must be considered, right? Answer: No. 378: The common presses used by riveters 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 brittle phenomenon. 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: The hammers commonly used by riveters include: hand hammers, sledge hammers, and claw hammers. 382: The chisels commonly used by riveters fall into two main categories: flat chisels and narrow chisels. 383: An iron-carbon alloy with a carbon content of less than 2.11% is called steel. 384: Steel with a carbon content of more than 0.6% is called high-carbon steel. 385: Steel can be classified according to its use into structural steel, tool steel, and special-purpose steel. 386: Steel can be classified by the shape of its end faces into sheets, tubes, profiles, and wires. 387: The basic methods for correcting steel deformation are cold working correction and heating correction. 388: Assembly fixture: Refers to the process equipment used during assembly to apply external forces to parts in order to achieve a reliable positioning of them. 389: The basic methods of cold working correction are manual correction and mechanical correction. 390: Heating correction types: full heating correction and partial heating correction. 391: The shapes of the heating zone corrected by local heating are point-shaped, line-shaped, and triangular. 392: The deformations of angle steel include twisting, bending, and angular deformation. 393: The deformations of channel steel include twisting, bending, and local deformation of the flanges. 394: Cold working correction: Correction carried out at room temperature is called cold working correction. 395: Separation includes three processes: blanking, punching, and cutting. 396: Stamping: The process of shaping sheet metal by separation or deformation to obtain finished parts. 397: What are the advantages of stamping? Answer: Good product quality, high productivity, material savings, cost reduction, and easy automation. 398: Bending forming: A processing method in which the blank is bent into the desired shape. 399: The basic forms of riveting are: butting, lap jointing, and corner jointing. 400: Riveting: Using rivets to join two or more components together into a single unit. 401: Common types of rivets include: half-round head, countersunk head, semi-countersunk head, flat head, flat-cone head, oval head, and flat head. 402: The types of riveting include: strong riveting, tight riveting, and secure riveting. 403: Assembly: The process of combining various parts into components in accordance with certain technical requirements. 404: The three elements of assembly are: positioning, support, and clamping. 405: The connection methods for metal structures include welding, riveting, bolted connections, and a combination of riveting and welding. 406: Common tools used for pattern making include chalk lines, slate pencils, drawing needles, rulers, pattern punches, and hand hammers. 407: The main methods for finding the intersection line are: the element line method, the auxiliary plane method, and the spherical surface method. 408: Methods for finding the actual length of a straight line segment include: the rotation method, the right triangle method, the plane transformation method, and the branch line method. 409: The methods for creating an expanded diagram include graphical methods and computational methods. 410: Common expansion methods include: the parallel lines method, the radial lines method, and the triangle method. 411: The shear fracture surface of materials can be divided into: chamfered corners, bright zones, shear zones, and burrs. 412: Correction methods: manual correction, mechanical correction, flame correction. 413: Datum: Points, lines, and planes on a part diagram used to determine the position of other points, lines, and planes. 414: Plasticity: The ability of metal materials to undergo permanent deformation without breaking under external forces. 415: Toughness: The ability of metal materials to resist destruction under impact loads. 416: Methods to prevent welding deformation include the counter-deformation method, rigid fixation method, and proper welding sequence. 417: Spatial linear projection has authenticity, accumulation, and contraction. 418: Intersection line: The line formed by the intersection of a plane with a solid. 419: Intersection line: The line where the surfaces are intersected as a result of the intersection of two planes. 420: View types: basic view, partial view, inclined view, rotated view. 421: The basic views include: front view, top view, left view, right view, bottom view, and rear view. 422: Types of sectional views: full section, half section, and partial section. 423: 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. 424: Tapping: Using a tap to cut internal threads on the wall of a hole. 425: 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. 426: Tapping: Using a tap to cut threads on the outer diameter of a round rod or tube. 427: 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. 428: Leaving a bevel edge when cutting grooves can prevent the joint from burning through. 429: Methods for cutting grooves include wind-blade machining, mechanical machining, gas cutting for grooving, and carbon arc gas gouging for grooving. 430: Carbon arc gouging: This method uses the high temperature of a carbon electrode arc to melt a portion of the metal, and then compressed air is used to blow away the melted metal, thereby achieving the purpose of gouging or cutting the metal. 431: Grinding can be used to remove burrs from the edges of weld scars on metal sheets, to polish welds, and to prepare welds on pressure vessels for further inspection. 432: Bending forming: Curving flat blanks, profiles, or tubes at a certain angle and with a specific curvature to create parts of a particular shape. 433: Springback phenomenon: When a material is bent, it undergoes elastic deformation; once the external force is removed, part of this elastic deformation is reversed, resulting in changes to the shape and angle of the bent component. 434: The common bending methods used by riveters include press bending, roll bending, rolling, and hot and cold plate bending. 435 ； Factors affecting bending forming include: bending force, springback, minimum bending radius, and cross-sectional shape. 436: How is the magnitude of the bending force determined, based on the mechanical properties of the material being bent, the method and type of bending, as well as the shape of the bent part? 437: The factors that affect the elastic recovery of bending include the mechanical properties of the material being bent, the relative bending radius of the material, the bending angle, and some other factors. 438: 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. 439: The factors affecting the change in cross-sectional shape during bending include the relative bending radius, the geometric characteristics of the cross-section, and the bending method. 440: What is the impact of heating steel on its bending processing? Answer: When steel is heated, the bending force required decreases, the springback phenomenon disappears, and the minimum bending radius is reduced, which facilitates controlling deformation according to processing requirements. 441: Is heating and bending usually used at room temperature? 442: Why is the heating temperature of steel restricted 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. 443: 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. 444: Bending: A processing method that uses bending dies on a press to achieve bending formation. 445: The bending deformations of materials include free bending, contact bending, and corrective bending. 446: 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. 447: Roll bending: A processing method for bending shapes on a rolling bench. 448: On symmetric three-roll plate rolling machines, (pre-bending at both ends and leaving machining allowance) is often used to eliminate the straight edges of the workpiece. 449: Into which two types can rolling be divided? Which one do riveters usually use? Answer: There are non-thinning calendering and thinning calendering. Riveters commonly use non-thinning rolling. 450: When rolling conical surfaces, it is necessary to 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.