The technical requirements for mechanical drawings (including parts drawings and assembly drawings) in “basic requirements for product drawings and design documents drawings” can be roughly divided into the following five aspects:
① The geometric accuracy is shown in the figure below
② The process requirements of processing and assembly refer to the process requirements put forward to ensure the product quality
③ Physical and chemical parameters refer to the requirements for the composition, microstructure and properties of materials
④ Product performance and testing requirements refer to the requirements for use and commissioning
General technical requirements
1. Remove oxide scale from parts.
2. There should be no scratch, scratch and other defects on the surface of parts.
3. Remove burr and flash.
▌ heat treatment requirements
1. After quenching and tempering, hrc50-55.
2. High frequency quenching, 350 ~ 370 ℃ tempering and hrc40 ~ 45 for the parts.
3. Carburizing depth is 0.3mm.
4. High temperature aging treatment.
▌ tolerance requirements
1. The unmarked form tolerance shall meet the requirements of gb1184-80.
2. The allowable deviation of the length dimension not indicated is ± 0.5mm.
3. The casting tolerance zone is symmetrical to the basic dimension configuration of the blank casting.
▌ edges and corners of parts
1. Fillet radius R5 is not noted.
2. The undeclared chamfer is 2 × 45 degrees.
3. Sharp corner / sharp edge blunt.
▌ assembly requirements
1. All seals must be soaked with oil before assembly.
2. It is allowed to use oil heating for hot charging when assembling rolling bearing, and the oil temperature shall not exceed 100 ℃.
3. After the gear is assembled, the contact spot and backlash on the tooth surface shall comply with the provisions of GB10095 and gb11365.
4. When assembling the hydraulic system, it is allowed to use sealing packing or sealant, but it should be prevented from entering the system.
5. The parts and components (including purchased parts and outsourcing parts) entering the assembly must have the certificate of inspection department before assembly.
6. Parts must be cleaned and cleaned before assembly, without burr, flash, scale, rust, chip, oil stain, colorant and dust.
7. Before assembly, the main fit dimensions of parts and components, especially the interference fit dimensions and relevant accuracy shall be rechecked.
8. Parts shall not be knocked, touched, scratched or rusted during assembly.
9. When fastening screws, bolts and nuts, it is forbidden to strike or use improper screwdrivers and spanners. After tightening, the screw groove, nut, screw and bolt head shall not be damaged.
10. For fasteners with specified tightening torque requirements, torque wrench must be used and tightened according to the specified tightening torque.
11. When multiple screws (bolts) are used to fasten the same part, the screws (bolts) shall be tightened crosswise, symmetrically, gradually and evenly.
12. The taper pin and the hole shall be painted for inspection during assembly, and the contact rate shall not be less than 60% of the fitting length, and shall be evenly distributed.
13. The flat key and the two sides of the keyway on the shaft shall be in even contact, and there shall be no clearance on the mating surface.
14. The number of tooth surfaces contacted by spline assembly at the same time shall not be less than 2 / 3, and the contact rate shall not be less than 50% in the direction of length and height of key teeth.
15. After the sliding flat key (or spline) is assembled, the parts can move freely without uneven tightness.
16. Remove the excess adhesive after bonding.
17. The semicircular hole of bearing outer ring, open bearing seat and bearing cover shall not be stuck.
18. The outer ring of the bearing shall be in good contact with the semicircular hole of the open bearing seat and bearing cover. During color inspection, the outer ring of the bearing shall be in uniform contact with the bearing seat within 120 ° symmetrical to the center line and the bearing cover within 90 ° symmetrical to the center line. When checking with a feeler gauge within the above range, the 0.03mm feeler gauge shall not be inserted into 1 / 3 of the outer ring width.
19. After assembly, the outer ring of the bearing shall contact the end face of the bearing cover at the locating end evenly.
20. After the rolling bearing is installed, it should rotate flexibly and smoothly by hand.
21. The joint surfaces of the upper and lower bearing shells should be closely adhered to each other and checked with a 0.05mm feeler gauge.
22. When fixing the bearing bush with locating pin, reaming and pin distribution shall be carried out under the condition that the surface and end face of the Bush mouth are level with the opening and closing surface and end face of the relevant bearing hole. The pin shall not be loose after being driven.
23. The contact between the bearing body and the bearing seat of spherical bearing shall be uniform, and the contact shall not be less than 70% by color coating method.
24. When the surface of alloy bearing liner turns yellow, it is not allowed to use. There is no nucleation phenomenon within the specified contact angle. The nucleation area outside the contact angle shall not be greater than 10% of the total area of non-contact area.
25. The reference end face of gear (worm gear) shall fit with the shaft shoulder (or end face of locating sleeve), and it cannot be checked with 0.05mm feeler gauge. The perpendicularity between gear reference end face and axis shall be ensured.
26. The joint surface of gearbox and cover shall be in good contact.
27. Before assembly, strictly check and remove the residual sharp angle, burr and foreign matter during parts processing. Ensure that the seal will not be scratched when installed.
▌ casting requirements
1. Cold shut, crack, shrinkage cavity, penetrating defect and serious incomplete defect (such as under casting, mechanical damage, etc.) are not allowed on the surface of casting.
2. The casting shall be cleaned without burr and flash, and the riser on the non machining surface shall be cleaned and flush with the casting surface.
3. The casting characters and marks on the non machined surface of the casting shall be clear and legible, and the position and font shall meet the requirements of the drawing.
4. The roughness of the non machined surface of the casting, R in sand casting, is not more than 50 μ M.
5. The pouring riser and flying thorn should be removed. The residual amount of pouring and riser on the non machined surface should be leveled and polished to meet the surface quality requirements.
6. The molding sand, core sand and core bone on the casting shall be removed.
7. For the parts with inclination, the size tolerance zone should be arranged symmetrically along the inclined plane.
8. The molding sand, core sand, core bone, fleshy, sticky sand, etc. on the casting shall be leveled and cleaned.
9. Correct the wrong shape and casting deviation of boss to achieve smooth transition and ensure appearance quality.
10. The depth of the wrinkles on the non machined surface of the casting should be less than 2 mm, and the spacing should be more than 100 mm.
11. The non machined surface of machine product castings should be shot peened or roller treated to meet the requirement of cleanliness Sa21 / 2.
12. Casting must be water toughened.
13. The surface of the casting should be flat, and the gate, burr and sand sticking should be removed.
14. Casting defects such as cold shut, crack and hole which are harmful to use are not allowed.
▌ painting requirements
1. Rust, oxide scale, grease, dust, soil, salt and dirt must be removed from the surface of all steel parts to be coated before painting.
2. Before derusting, use organic solvent, alkali, emulsifier and steam to remove grease and dirt on the surface of steel products.
3. The time interval between shot peening or manual derusting and priming shall not be more than 6h.
4. The surface of riveted parts in contact with each other must be coated with 30-40 μ m antirust paint before connection. Lapped edges shall be sealed with paint, putty or adhesive. The primer damaged by processing or welding shall be repainted.
▌ piping requirements
1. All pipes shall be deburred and chamfered before assembly. Use compressed air or other methods to clear the debris and floating rust on the inner wall of the pipe.
2. Before assembly, all steel pipes (including prefabricated pipes) shall be degreased, pickled, neutralized, washed and antirust treated.
3. During assembly, the pipe clamp, support, flange, joint and other parts fixed by screw connection shall be tightened to prevent loosening.
4. Pressure test shall be conducted on the welding parts of prefabricated pipes.
5. When piping replacement or transfer, the pipe separation port must be sealed with adhesive tape or plastic pipe to prevent any foreign matters from entering, and the label must be tied.
▌ repair weldment requirements
1. The defects must be completely removed before welding, and the groove surface shall be smooth without sharp corners.
2. According to the defects of steel castings, the welding defects can be removed by shovel, grinding, carbon arc gouging, gas cutting or machining.
3. The dirt such as sand, oil, water and rust within 20 mm around the welding area and groove must be thoroughly cleaned.
4. In the whole welding process, the temperature of steel casting preheating zone shall not be lower than 350 ° C.
5. If conditions permit, welding should be carried out in horizontal position as far as possible.
6. During repair welding, the welding rod shall not swing laterally.
7. When stacking welding on the surface of steel castings, the overlap between weld beads shall not be less than 1 / 3 of the weld bead width. The welding flesh is full and there is no burn, crack and obvious nodulation on the welding surface. The weld appearance is beautiful, without defects such as undercut, slag, air hole, crack and spatter, and the welding wave is uniform.
▌ forging requirements
1. The nozzle and riser of ingot should have enough cutting amount to ensure that the forging has no shrinkage cavity and serious deflection.
2. Forgings shall be forged on forging press with sufficient capacity to ensure full internal penetration of forgings.
3. The forgings shall not have visible cracks, folds and other appearance defects that affect the use. The local defects can be removed, but the cleaning depth shall not exceed 75% of the machining allowance. The defects on the non machined surface of forgings shall be cleaned and smoothly transited.
4. There is no white spot, internal crack and residual shrinkage cavity in forging.
▌ requirements for machined parts
1. The parts should be inspected and accepted according to the process, and the next process can be carried out only after the previous process is qualified.
2. No burr is allowed on the machined parts.
3. The finished parts shall not be placed directly on the ground, and necessary support and protection measures shall be taken. The machined surface shall be free from rust and other defects such as bumps and scratches that affect the performance, service life or appearance.
4. There shall be no peeling on the surface after rolling finishing.
5. There should be no oxide scale on the surface of the parts after heat treatment in the final process. There should be no annealing on the finish machined mating surface and tooth surface
6. The machined thread surface is not allowed to have defects such as black skin, bumping, random buckle and burr.