❑ General technical requirements
1. Remove oxide scale from parts.
2. There shall be no scratch, scratch and other defects that damage the part surface on the part processing surface.
3. Remove burrs and fins.
❑ Heat treatment requirements
1. After quenching and tempering, HRC50~55.
2. Parts shall be subject to high-frequency quenching, 350~370 ℃ tempering and HRC40~45.
3. Carburizing depth 0.3mm.
4. Carry out high temperature aging treatment.
❑ Tolerance requirements
1. Undeclared shape tolerance shall meet the requirements of GB1184-80.
2. The allowable deviation of unspecified length is ± 0.5mm.
3. The casting tolerance zone is symmetrical to the basic dimension configuration of the blank casting.
❑ Edge angle of parts
1. Undeclared fillet radius R5.
2. Undeclared chamfers are all 2 × 45°。
3. Sharp corner/sharp corner/sharp edge rounding off.
❑ Assembly requirements
1. All seals must be soaked with oil before assembly.
2. It is allowed to use oil heating for hot assembly of rolling bearings, and the oil temperature shall not exceed 100 ℃.
3. After the gear is assembled, the contact pattern and backlash of the gear surface shall comply with the provisions of GB10095 and GB11365.
4. When assembling the hydraulic system, it is allowed to use sealing filler or sealant, but it should be prevented from entering the system.
5. The parts and components (including purchased parts and outsourced parts) to be assembled must have the qualification certificate of the inspection department before assembly.
6. The parts must be cleaned and cleaned before assembly, without burrs, fins, oxide skin, rust, chips, oil stains, colorants, dust, etc.
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, bumped, scratched or rusted during assembly.
9. When fastening screws, bolts and nuts, it is forbidden to strike or use inappropriate screwdrivers and wrenches. The screw groove, nut, screw and bolt head shall not be damaged after fastening.
10. For fasteners with specified tightening torque requirements, torque wrenches must be used and tightened according to the specified tightening torque.
11. When the same part is fastened with multiple screws (bolts), all screws (bolts) shall be tightened crosswise, symmetrically, step by step and evenly.
12. The taper pin shall be painted with the hole during assembly, and its contact rate shall not be less than 60% of the fitting length, and shall be evenly distributed.
13. The flat key and two sides of the keyway on the shaft shall be in uniform contact, and there shall be no gap between their mating surfaces.
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 assembly of the flat key (or spline) of the sliding fit, the corresponding accessories can move freely without uneven tightness.
16. Excess adhesive shall be removed after bonding.
17. The semicircle 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 the color inspection, it shall be in uniform contact with the bearing seat within 120 ° symmetrical to the centerline and with the bearing cover within 90 ° symmetrical to the centerline. 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. The bearing outer ring shall contact the end face of the locating end bearing cover evenly after assembly.
20. The rolling bearing shall rotate flexibly and stably by hand after installation.
21. The joint surface of the upper and lower bearing pads shall be close to each other and cannot be checked with a 0.05mm feeler gauge.
22. When fixing bearing pads with locating pins, drill, ream and match pins under the condition that the pad mouth surface and end face are flush with the opening and closing surfaces and end faces of relevant bearing holes. The pin shall not be loose after driving.
23. The bearing body and bearing seat of spherical bearing shall be in uniform contact, and the contact shall not be less than 70% when checked by painting method.
24. When the surface of alloy bearing liner is yellow, it is not allowed to use it. There is no nucleation within the specified contact angle. The nucleation area outside the contact angle shall not be greater than 10% of the total area of the non-contact area.
25. The reference end face of the gear (worm gear) should fit with the shaft shoulder (or the end face of the positioning sleeve), and cannot be checked with a 0.05mm feeler gauge. The perpendicularity between the gear reference end face and the axis shall be ensured.
26. The interface between the gearbox and the cover shall be in good contact.
27. Before assembly, strictly check and remove the sharp corners, burrs and foreign matters left during part processing. Ensure that the seal is not scratched during installation.
❑ Requirements for castings
1. The casting surface is not allowed to have cold shut, crack, shrinkage cavity, penetrating defects and serious defects (such as under casting, mechanical damage, etc.).
2. The casting shall be cleaned without burr and flash, and the gate and riser on the non machining indication shall be cleaned and flush with the casting surface.
3. The casting words 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. Roughness of non machined surface of casting, sand casting R, not greater than 50 μ m。
5. The casting shall be cleaned of the sprue, riser, flying thorn, etc. The residual amount of gating and riser on the non machined surface shall be leveled and polished to meet the surface quality requirements.
6. The molding sand, core sand and core bone on the casting shall be cleaned.
7. The dimensional tolerance zone of castings with inclined parts shall be symmetrically arranged along the inclined plane.
8. Moulding sand, core sand, core bone, fleshy, sticky sand, etc. on the casting shall be scraped and cleaned.
9. The wrong type and boss casting deviation shall be corrected to achieve smooth transition and ensure the appearance quality.
10. The wrinkle on the non machined surface of the casting shall be less than 2mm deep and more than 100mm apart.
11. The non machined surfaces of machine product castings shall be shot blasted or roller treated to meet the requirements of cleanliness Sa2 1/2.
12. Castings must be treated with water toughening.
13. The casting surface shall be flat, and the gate, burr, sand, etc. shall be removed.
14. The casting shall be free from cold shut, crack, hole and other casting defects detrimental to use.
Coating requirements
1. Rust, oxide skin, grease, dust, soil, salt and dirt must be removed from the surface of all steel products to be coated before painting.
2. Before rust removal, use organic solvent, lye, emulsifier, steam, etc. to remove grease and dirt on the surface of steel products.
3. The time interval between the surface to be painted after shot blasting or manual derusting and the primer shall not be more than 6h.
4. The surfaces of riveted parts in contact with each other must be coated with a thickness of 30-40 before connection μ M Anti rust paint. The overlapping edges shall be sealed with paint, putty or adhesive. The primer damaged due to processing or welding shall be repainted.
❑ Piping requirements
1. Before assembly, all pipes shall be free of flash, burr and chamfer. Use compressed air or other methods to clear the sundries and floating rust attached to the inner wall of the pipe.
2. Before assembly, all steel pipes (including prefabricated pipes) shall be subject to degreasing, pickling, neutralization, water washing and rust prevention.
3. During assembly, screw down the pipe clamp, support, flange, joint and other parts fixed by threaded connection to prevent looseness.
4. The welding parts of prefabricated pipes shall be subject to pressure test.
5. When piping is replaced or transferred, the pipe separation port must be sealed with tape or plastic pipe to prevent any foreign matter from entering, and a label must be attached.
Requirements for repair weldments
1. The defects must be completely removed before welding, and the groove surface should be smooth and smooth without sharp corners.
2. According to the defects of steel castings, the defects in the welding area can be removed by digging, grinding, carbon arc gouging, gas cutting or machining.
3. Sand, oil, water, rust and other dirt in the welding area and within 20mm around the groove must be thoroughly cleaned.
4. During the whole welding process, the temperature of the preheating area of the steel casting shall not be lower than 350 ° C.
5. If conditions permit, welding shall be carried out in horizontal position as far as possible.
6. During repair welding, the welding rod shall not swing laterally.
7. When the surface of steel casting is welded, the overlap between weld beads shall not be less than 1/3 of the weld bead width. The welding flesh is full, and the welding surface is free of burns, cracks and obvious nodules. The appearance of the weld is beautiful, and there is no undercut, slag, air hole, crack, splash and other defects; The welding wave is uniform.
Requirements for forgings
1. The nozzle and riser of the ingot shall have enough removal to ensure that the forgings are free of shrinkage cavity and serious deflection.
2. The forgings shall be forged and formed on a forging press with sufficient capacity to ensure full internal penetration of the forgings.
3. Forgings are not allowed to have visible cracks, folds and other appearance defects affecting use. Local defects can be removed, but the cleaning depth shall not exceed 75% of the machining allowance. Defects on the non machined surface of forgings shall be cleaned and smoothly transited.
4. Forgings are not allowed to have white spots, internal cracks and residual shrinkage cavities.
Requirements for machining parts
1. Parts shall be inspected and accepted according to the process, and can be transferred to the next process only after the previous process passes the inspection.
2. The machined parts are not allowed to have burrs.
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 of rust and other defects that may affect the performance, service life or appearance.
4. The surface for rolling finishing shall be free of peeling after rolling.
5. There shall be no oxide skin on the surface of parts after heat treatment in the final process. The finished mating surface and tooth surface shall not be annealed.
6. The machined thread surface shall be free of defects such as black skin, bump, random thread and burr.