During the work of the mechanical designer, every small point must be considered very clearly.
As a rigorous worker, you must understand those complicated mechanical knowledge points.
1. The main forms of metal structure are: frame structure, container structure, box structure, general component structure.
2. According to the nature of the process, the riveting operation can be divided into: preparation, setting out, processing and forming, assembly and connection.
3. The connection methods of metal structure are: riveting, welding, riveting and welding hybrid connection, bolt connection.
4. In the machinery manufacturing industry, riveting workers belong to the category of thermal processing.
5. Hot processing: All or part of the metal materials are processed by heating.
6. The structure of the hanger structure is mainly made of (profile).
7. The container structure is a structure mainly made of (plate).
8. The box structure and general structure are made by mixing (plate) and (profile).
9. Material preparation refers to the preparation of (raw materials) and (part blanks).
10. Steel plates and profiles can cause deformation during (transport, lifting, storage).
11. The deformation of the steel will affect the normal operation of parts (lifting, blanking, gas cutting) and other processes.
12. If the deformation of the parts during processing is not corrected, it will affect the correct assembly of the structure.
13. The deformation caused by welding will reduce the (precision) of the assembly and cause additional stress inside the steel structure, affecting (the strength of the component).
14. The deformation of flat steel includes: bending, twisting, bending and twisting combined deformation.
15. The multi-roll straightening machine can be divided into: parallel straightening machine for upper and lower roller rows and tilt straightening machine for upper and lower rollers according to the arrangement of shaft rollers and the position of adjusting rollers. (Source: metal processing)
16. The heating methods for flame correction are: point, line and triangle heating.
17. The effect of flame straightening is determined by (heating position and heating temperature).
18. The methods of correction are: mechanical correction, manual correction, flame correction, high-frequency heat correction.
19. Lofting and numbering materials are the first process of making metal structures.
20. Lofting and numbering materials: will directly affect product quality and have a direct impact on production cycle and cost.
21. Commonly used quantities for lofting include: wooden folding ruler, ruler, steel tape measure, steel ruler, etc.
22. Common tools for setting out are: drawing rule, ground rule, sample punching, drawing needle, small hammer.
23. The procedure for setting out the full scale is: linear setting out, structural setting out, and opening out.
24. The contents of the exhibition open sample include: plate thickness processing, unfolding drawing, and production of sample materials.
25. The model is divided according to its use: material model, model inspection model, positioning model.
26. The model is generally used: a thin iron sheet with a thickness of 0.5–2 mm.
27. The drawing methods of template and sample rod mainly include: straight drawing method and transition drawing method.
28. How to use reasonable materials?
Answer: It is necessary to concentrate the use of rows and surplus materials.
29. The curve is divided into plane curve and space curve.
30. The methods for finding the real length of a straight line segment include: rotation method, right triangle method, branch line method, and surface replacement method.
31. The steps to develop the opening pattern are: to draw intersecting lines, solid long lines, and cross-sectional solid shapes through geometric drawing, and then to make an unfolded drawing.
32. The basic method of finding the plane three-dimensional intercept line is: ridge method and prism method.
33. The basic method of finding the three-dimensional intersection line of a curved surface is: the meridian method and the weft method.
34. The main methods of finding intersecting lines are: auxiliary plane method, prime line method, spherical method.
35. What are the characteristics of intersecting lines?
Answer: (1) Intersecting lines are the common lines and dividing lines that intersect two bodies.
(2) Because the shape has a certain range, the intersection line is always closed.
36. Intersection line: The intersection line of the section plane and the three-dimensional surface.
37. Prime line: The bus bar is called prime line at any position on the surface of the component.
38. Commonly used unfolding methods are: parallel line method, radiation method, triangle method.
39. The division method of spherical surface usually includes: banding method, block method, and lobe method.
40. The main content of the plate thickness treatment is: to determine the neutral layer of the bending piece and to eliminate the interference of the plate thickness.
41. The material length of angle steel bending parts is calculated by (center of gravity layer).
42. Shearing machines for cutting straight lines include: Longmen diagonal shearing machine, horizontal wood diagonal shearing machine, combined punching and shearing machine tool.
43. The shear curve machine tools include: disc shears and vibration shears.
44. What are the characteristics of vibrating shears?
Answer: The vibrating shear can cut various curves and inner holes.
45. The combined shear punching machine consists of (inclined shear, steel shear, small punch).
46. Try to analyze the transmission sequence of the shearing machine as follows: original moving part → transmission part → workpiece.
47. The front and rear baffles of the gantry shearing machine have: positioning function.
48. On the gantry or oblique shearing machine, the positioning shears are: shearing shear positioning, tailgate shearing, baffle shearing.
49. The shearing force acting on the material by the oblique shear can be decomposed into: shearing force, horizontal pulling force and separating force.
50. The shearing machine is not suitable for shearing alloy materials and hardened materials.
51. The cutting oxygen pressure should be selected according to: workpiece thickness, torch nozzle aperture, and oxygen purity.
52. Generally, the ignition point of carbon steel in oxygen is 1100-1150 ℃.
53. Metal materials that can meet the conditions of gas cutting include pure iron, low carbon steel, medium carbon steel, and ordinary low alloy steel.
54. The process of gas cutting is: the preheating of the metal, the burning of the metal, and the oxides are blown away.
55. What is the role of circular die? What is it composed of?
Answer: It is a tool for machining external threads, which consists of cutting part, positioning part and chip discharge hole.
56. What is the form of the bevel?
Answer: with the type of material, thickness, welding method, and mechanical properties of the product.
57. Frosting: processing the surface of the workpiece with a grinding wheel is called frosting.
58. Grinding tools mainly include pneumatic grinders and electric grinders.
59. During the bending process, what deformation will happen to the steel?
Answer: Elastic deformation and plastic deformation will occur.
60. The bending forming methods commonly used by riveters include cold bending, hot bending, manual bending, and mechanical bending.
61. Material bending deformation during bending and bending includes free bending, contact bending, and correction bending.
62. The change of the cross-sectional shape of the material during the bending process is related to the relative bending radius, the geometric characteristics of the cross-section, and the bending method.
63. The method to prevent the blank deviation during the bending process is to have a material holding device and a positioning hole.
64. Roll bending machines include plate rolling machines and section steel bending machines.
65. The main processes of manual bending include scribing, sand filling and heating bending.
66. There are three connection methods for metal structures: rivet connection and threaded connection welding.
67. The selection of the connection method should consider the strength of the components, working environment, materials, construction conditions and other factors.
68. The riveted joints have butt joints and corner joints.
69. The forms of solid rivet heads are semi-circular head, countersunk head, and semi-counter-sunk head.
70. The AC arc welding machines mainly include BX1-330 and BX-500.
71. The basic operation process of hot riveting is to be fastened by riveting parts, repairing holes, heating rivets, nailing and piercing, top nailing and riveting.
72. The types of riveting include: strong riveting, tight riveting, and tight riveting.
73. Tools for repairing holes are: reamer.
74. Commonly used anti-loosening measures for threaded connections are: increased friction and mechanical anti-loosening.
75. The welding arc consists of: anode area, cathode area and arc post.
76. Electric welding machines mainly include: DC welding machines and AC welding machines.
77. Local deformation refers to the deformation of a part of the component, including angular deformation, wave deformation, and local unevenness.
78. Welding is divided into horizontal welding, vertical welding, horizontal welding and overhead welding according to the spatial position.
79. In the welding process, which three directions of electrode movement?
Answer: There is movement in the direction of the molten pool, movement in the welding direction, and lateral swing.
80. The three elements of assembly are positioning, support and clamping.
81. The manual clamp has a screw clamp, a wedge clamp, a lever clamp, and an eccentric clamp.
82. Non-manual clamps have pneumatic clamps, hydraulic clamps, and magnetic clamps.
83. The screw clamp has the functions of clamping, pressing, pushing and supporting.
84. Commonly used measurement items in assembly include linear dimension, parallelism, perpendicularity, coaxiality and angle.
85. The support form of the workpiece in the assembly is assembly platform support and assembly tire frame support.
86. Assembled tire frames can be divided into general tire frames and special tire frames according to their functions.
87. Commonly used positioning methods in assembly include scribe line positioning, model positioning, and positioning component positioning.
88. The basic methods for finding the plane intersection line are the facet method and the edge method.
89. Hot riveting is generally composed of four people. What is their division of labor?
Answer: One person heats and passes, one person wears the nail, one person pushes the nail, and one person rivets.
90. What is the role of the flat tail in a tapered shank bit?
Answer: It is used to increase the transmitted torque to prevent the drill bit from hitting in the spindle hole or drill sleeve.
91. What is the role of the guide in the drill bit?
Answer: It can maintain the straight drilling direction during the cutting process. At the same time, it has the function of smoothing the hole wall and is also a backup part of the cutting part.
92. What bad phenomena will occur when the hole is about to be drilled?
Answer: When the drill bit just drills through the workpiece, the axial resistance suddenly decreases. Due to the clearance of the feed machine of the drilling machine and the sudden recovery of elastic deformation, the drill bit will automatically cut in at a large feed rate, causing the drill bit to break or the drilling quality reduce.
93. What is the role of cutting fluid when drilling?
Answer: Reduce friction, reduce bit resistance and cutting temperature, improve the cutting ability of the bit and the surface quality of the hole wall.
94. Cutting usage is the general term for cutting speed feed and cutting depth.
95. Grinding is the method of machining the surface of the workpiece with a grinding wheel.
96. Unfolding The process of spreading the surface or parts of a metal structure on a plane in order according to its actual shape and size is called unfolding.
97. The methods of drawing the unfolded drawing include parallel line method, triangle method and radiation method.
98. The development condition of the parallel line method is that the prime lines on the surface of the component are parallel to each other and reflect the real length on the projection surface.
99. Plate thickness processing includes: determining the neutral layer of the bending piece and eliminating the interference of the plate thickness.
100. The change of the position of the plate thickness neutral layer is related to: the plate bending radius and the plate thickness.
101. The general principle for the treatment of the thickness of intersecting parts is: the length of the expansion is based on the size of the neutral layer of the component, and the height of the curve in the expansion is based on the height of the contact point of the component.
102. The main contents of lofting are: plate thickness processing, unfolding drawing and making number material template based on the developed component unfolding drawing.
103. Shearing equipment commonly used by riveters include: gantry shears, bevel shears, disc shears, punching shears combined punching shears.
104. According to the number and arrangement of shaft rollers, the plate bending machine can be divided into three types: symmetrical three-roller, asymmetrical three-roller and four-roller.
105. The punching die can be divided into simple die, guided die and compound die according to the structure.
106. The structural feature of the compound punching die is that it has a convex and concave die that functions as both a blanking punch and a punching die. (Source: metal processing)
107. Punching force: refers to the maximum resistance of the material to the die during punching.
108. The deformation process of sheet material separation during punching can be divided into: elastic deformation stage, plastic deformation stage and shearing stage.
109. Minimum bending radius: The minimum value of the bending radius that the material can bend without damage.
110. Common methods to reduce the springback of crimped parts are: modified mold method and pressure correction method.
111. The purpose of using a blank holder during stretching is to prevent the edges of the stretched piece from wrinkling.
112. What is the function of the crank connecting rod mechanism of the crank press?
Answer: It can not only turn the rotary motion into a reciprocating linear motion, but also amplify the force.
113. Sheet metalworking manual forming includes: bending, arching, edge extraction, hemming, biting and correction.
114. Expansion model can be used for: material, manufacturing separation mold and manufacturing milling model.
115. Edge setting: The operation of stretching and thinning the edge material of the deformed part during the forming process is called edge setting. There are thinning and thinning methods.
116. Pulling edge: Using the method of pulling and closing, the edge of the sheet is processed into a curved and curved workpiece.
117. Hemming: To increase the rigidity and strength of the edge of the workpiece, curling the edge of the workpiece is called curling.
118. Bite seam: The edge of two sheets or the two sides of a sheet are turned and bitten and pressed against each other, called the bite seam.
119. Board thickness treatment: a method adopted to eliminate the influence of the board thickness on the shape and size of the unfolded drawing.
120. The general steps for calculating the unfolded length of a curved piece are: divide the curved piece into straight sections and circular arc sections, calculate the length of each section separately, and add the calculated lengths.
121. Under what circumstances should the cut-out of profiled steel be used?
Answer: Angle steel, channel steel and I-beam are bent into a folded angle.
122. The whole punching process is divided into elastic deformation stage, plastic deformation stage and shearing stage.
123. Punching is a stamping process that uses a punching template to separate a part of a sheet from another part along a certain closed line.
124. There are two types of bolt connections: those that are subjected to axial tensile loading and those that are subjected to lateral effects.
125. The anti-loosening measures of the bolt connection include increased friction and mechanical anti-loosening.
126. Mechanical anti-loosening includes cotter pins, anti-back washers, anti-stop washers, and tandem wires.
127. The welding arc generates a strong and long-lasting discharge in the gaseous medium between the two electrodes.
128. Welding arc consists of cathode area, anode area and arc column.
129. What are the three directions of movement of the electrode?
Answer: Move in the direction of the molten pool; move in the welding direction; swing horizontally.
130. Welding seams can be divided into horizontal welding, vertical welding, horizontal welding, and overhead welding according to their spatial positions.
131. What are the characteristics of intersecting lines?
Answer: Both the public line and the dividing line on the surface of the two bodies are always closed in the space.
132. Intersecting line: A component composed of two or more geometric bodies intersecting each other.
133. The factors that affect the punching quality are: the gap between the dies; the center line of the male and female dies does not coincide; the working edge of the dies becomes blunt.
134. The general principle of die design is: strive to design the die under the prerequisite of ensuring stamping quality, easy to manufacture, simple process, low cost, and easy to use.
135. The purpose of calculating the calendering force is to select the calendering equipment correctly.
136. Free bending: When the bending is finished, the punch, blank, and die no longer impact each other.
137. Correction of bending: refers to the punch, blank, and die, and there is one impact after the three match, which corrects the bending piece.
138. What defects are easy to produce when pressing the head? (Source: metal processing)
Answer: Wrinkling and wrapping; straight edge pull marks and dents; micro-cracks on the outer surface; longitudinal tearing; deflection;
139. Expansion connection: the use of tube and tube sheet deformation to achieve a sealed and fast connection.
140. The purpose of calculating the punching force is to select the equipment capacity and design the mold reasonably.
141. What method can be used to reduce the punching force?
Answer: Diagonal blade die; step die; heating die.
142. The purpose of calculating the bending force is to select the bending press and design the mold.
143. What are the contents of tensile deformation?
Answer: The degree of die-attachment; the degree to which the material is allowed to deform.
144. How to determine the drawing times of the workpiece?
Answer: According to the maximum deformation and material elongation of the workpiece being pulled.
145. How to determine the stretch coefficient?
Answer: It depends on the properties of the material, the draw angle, the friction coefficient and whether the preform is prefabricated.
146. Brittle materials such as high carbon steel, high alloy steel, and cast iron are not suitable for cold work.
147. When the angle steel has complex deformation, the order of correction is: first correct the distortion, then correct the bending and finally correct the angle deformation.
148. Causes of deformation of the steel structure: one is caused by external force and the other is caused by internal stress.
149. Methods to eliminate welding residual stress 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 change in shape and size of the entire structure.
151. Hammer spreading method: the fiber structure of the metal plate is elongated by hammering.
152. The length of the rivet rod: determined according to the total thickness of the connected parts, the gap between the nail hole and the diameter of the nail rod, the riveting process and other factors.
153. The reason why the rivet head is too small after riveting is that the nail rod is short or the hole diameter is too large.
154. Welding can be divided into: welding, pressure welding, brazing according to the state of the metal.
155. Fusion welding: A method of using local heating to bring a welded joint to a molten state.
156. Clamping: It is to fix the parts after positioning with the help of external force, so as to keep the position unchanged during the processing.
157. Six-point positioning rule: Use six positioning points to limit the freedom of the part in space, so as to obtain the spatial position of the part.
158. Relative parallelism: refers to the parallelism of the measured line or surface on the part relative to the measurement reference line or surface.
159. Relative perpendicularity: refers to the perpendicularity of the measured line or surface on the part relative to the measurement reference line or surface.
160. The work clamps used in assembly include: assembly tools; assembly fixtures; assembly spreaders.
161. Commonly used assembly cranes include: wire ropes, iron chains, chain hoists and special spreaders.
162. How many guide forms are there for punching die?
Answer: There are two types of guide post, guide sleeve and guide plate.
163. How many parts are there in the punching die?
Answer: It consists of working part, material positioning part, unloading part and mold base.
164. What is the role of the gap between the drawing dies?
Answer: Reduce the friction between the material and the die and control the material flow in the cavity of the die.
165. According to its structure, the bite seam can be divided into: vertical single bite seam; vertical double bite seam; horizontal flat bite seam and various angle bite seams.
166. When the external force is removed, what is the reason why the bending piece springs back?
Answer: When bending manually, the outer surface of the sheet is tensioned and the inner surface is compressed, so springback occurs.
167. Cold arch is obtained by shrinking the edge of the sheet and placing it in the middle of the sheet, and hot arch is obtained by shrinking the sheet by heating. (Source: metal processing)
198. There are two methods to extract the edge, one is to use a common tool to extract the edge, and the other is to use the type tire to extract the edge.
169. Edge trimming: Edge trimming is to wrinkle the sheet first, and then flatten the wrinkle while preventing the stretch from recovering. In this way, the length of the sheet is shrunk and the thickness is increased.
170. The basic principle of edge trimming is that for the forming of convex curved flanges, the outer edge of the curved flat edge is contracted and thickened and shortened, forcing the vertical edge to have a curved shape.
171. The purpose of correction is to shorten the longer fibers and extend the shorter fibers by applying external force or local heating, so that the fibers of each layer tend to be consistent to achieve the purpose of correction.
172. The principle of flame correction is to use the deformation of the metal after local heating to offset the original deformation to achieve the purpose of correction.
173. The factors that affect the flame correction effect are: the rigidity of the workpiece; the heating position; the flame heat; the heating area and the cooling method.
174. The heating methods of flame correction are: point, line and triangle heating.
175. The factors that determine the process margin are: the influence of the lofting error; the influence of the error in the processing of the part; the influence of the assembly error; the influence of the welding deformation; the influence of the flame correction.
176. The model can be divided into: material model, forming model, positioning model and model rod according to its use.
177. Drawing methods include: direct drawing method and transition drawing method.
178. How to choose the baseline for lofting?
Answer: Take two perpendicular lines or planes; take two center lines as reference lines; take one plane and one center line as reference.
179. Stakeout tolerance: During the re-stakeout process, due to the influence of factors such as stakeout gage and tool accuracy and operation level, the actual sample drawing will have a certain size deviation. If this deviation is controlled within a certain range, it is called the stakeout permission error.
180. The structural lofting includes: determining the joint position and connection form of each part; giving necessary changes according to the actual production and processing capacity; calculating or measuring the material length of the part and the actual shape of the planar part; designing the tire tool or tire frame.
181. The methods for finding the real length of a straight line segment are: rotation method; right triangle method; changing surface method; branch method.
182. What is the drawing rule of the right triangle method to find the real length of a line segment?
Answer: The projection of the line segment on any projection plane is used as a right-angle side of the right triangle, and the projection length of the corresponding projection on the axis perpendicular to the plane is used as the other right-angle side, and the hypotenuse is the real length of the line segment.
183. The rotation method to find the real length: it is to rotate the general position of the space around a fixed axis into a parallel line, then the projection of the line on the projection plane parallel to it reflects the real length.
184. The methods to find the real length of the curve include: the method of changing faces; the method of expansion.
185. The method of changing surfaces: it is to set up a new projection surface parallel to the curve, then the projection of the curve on the surface reflects the real length.
186. Expansion method: It is to straighten one length in the curve view and keep the height in the other view unchanged.
187. The basic feature of the intercept line is that the intercept line must be a plane figure enclosed by a closed straight line or curve; the intercept line is the common line between the intercept plane and the three-dimensional surface. It is also assembled from the points on the three-dimensional surface.
188. The methods of finding the three-dimensional intercept line are: the facet method; the edge method.
189. The methods to find the three-dimensional intersection line of the curved surface are: the plain method and the weft method.
190. What are the characteristics of intersecting lines?
Answer: One is the common line intersecting the surfaces of the two bodies, and also the dividing line of the intersecting bodies; the second is that the intersecting lines are closed.
191. The essence of finding the intersecting line is to find a certain number of common points on the surface of the two bodies, and connect these common points in turn to obtain the desired point.
192. The selection principle of the method for finding the intersecting line is: using the prime method to obtain at least one projection of the intersecting line; using the auxiliary plane method to obtain the intersecting line, the intersection line should be the simplest geometric figure ; The spherical method is only applicable to the components where the rotating bodies intersect and the axes intersect.
193. Under what conditions, the intersection line is a plane curve? Is the front projection of the curve intersecting two straight lines?
Answer: When any two revolving bodies tangent to the same spherical surface intersect, the intersecting line is a plane curve. At this time, when the axes of the two revolving bodies are parallel to their basic projection surfaces, the intersecting line is on that surface The projection of is the intersection of two straight lines,
196: Straight grain surface: It is a surface formed by taking a straight line as a generatrix.
197: What are the characteristics of the cylinder?
Answer: All the prime lines are parallel to each other; when the cylinder is cut with parallel planes, the cross-sectional shape is the same.
198: What are the characteristics of the cone surface?
Answer: All the prime lines intersect at one point; when the cone is cut with planes parallel to each other, the cross-sectional shape is similar; the cut line crossing the top of the cone is a triangle.
199: During the deformation, the plastic deformation process of the material is divided into: the material bends; the material is stretched and deformed;
200: Stretching: It is a forming method in which the sheet material is plastically deformed according to an ideal curved surface under tension and overcomes springback.
