General Technical Requirements
1. Descaling of parts.
2. On the machined surface of the parts, there should be no scratches, abrasions and other defects that damage the surface of the parts.
3. Remove burrs and flash.
heat treatment requirements
1. After quenching and tempering treatment, HRC50～55.
2. The parts are subjected to high-frequency quenching, tempering at 350-370°C, HRC40-45.
3. Carburizing depth 0.3mm.
4. Carry out high temperature aging treatment.
Tolerance requirements
1. Unmarked shape tolerances should meet the requirements of GB1184-80.
2. The allowable deviation of the unmarked length is ±0.5mm.
3. The casting tolerance zone is symmetrical to the basic dimension configuration of the rough casting.
Part edges and corners
1. Fillet radius R5 is not specified.
2. All the chamfers not marked are 2×45°.
3. Sharp corners/sharp corners/sharp edges blunt.
Assembly requirements
1. Each seal must be saturated with oil before assembly.
2. Assembled rolling bearings are allowed to be heated by engine oil for thermal assembly, and the temperature of the oil must not exceed 100°C.
3. After the gear is assembled, the contact spots and backlash of the tooth surface should meet the requirements of GB10095 and GB11365.
4. Sealing packing or sealant is allowed when assembling the hydraulic system, but should be prevented from entering the system.
5. Parts and components entering assembly (including purchased parts and outsourced parts) must have a certificate of conformity from the inspection department before they can be assembled.
6. Parts must be cleaned and cleaned before assembly without burrs, flashes, scale, rust, chips, oil stains, colorants and dust, etc.
7. Before assembly, the main matching dimensions of parts and components, especially the interference fit dimensions and related precision, should be rechecked.
8. Parts are not allowed to be bumped, bumped, scratched or corroded during the assembly process.
9. When tightening screws, bolts and nuts, it is strictly forbidden to strike or use unsuitable screwdrivers and wrenches. After tightening, the screw slots, nuts and screws, and the head of the bolt must not be damaged.
10. For fasteners with specified tightening torque requirements, a torque wrench must be used and tightened according to the specified tightening torque.
11. When the same part is fastened with multiple screws (bolts), each screw (bolt) must be tightened crosswise, symmetrically, step by step, and evenly.
12. When the taper pin is assembled, it should be painted and checked with the hole, and its contact rate should not be less than 60% of the mating length, and it should be evenly distributed.
13. The flat key should be in uniform contact with both sides of the keyway on the shaft, and there should be no gap on the mating surface.
14. The number of tooth surfaces that the spline assembly contacts 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 the length and height of the spline teeth.
15. After the flat key (or spline) of sliding fit is assembled, the matching parts can move freely, and there must be no uneven tension.
16. After bonding, the excess adhesive that flows out should be removed.
17. The outer ring of the bearing and the semicircular hole of the open bearing housing and the bearing cover are not allowed to be stuck.
18. The outer ring of the bearing should be in good contact with the semicircular hole of the open bearing seat and the bearing cover. When checking with coloring, it should be within the range of 120° symmetrical to the centerline of the bearing seat and 90° symmetrical to the centerline of the bearing cover. Even contact. When checking with a feeler gauge within the above range, the 0.03mm feeler gauge must not be inserted into 1/3 of the width of the outer ring.
19. After assembly, the outer ring of the bearing should be in even contact with the end surface of the bearing cap at the positioning end.
20. After the rolling bearing is installed, it should be turned flexibly and smoothly by hand.
21. The joint surfaces of the upper and lower bearing bushes should be closely attached, and cannot be checked with a 0.05mm feeler gauge.
22. When using positioning pins to fix the bearing bush, drilling, reaming and pin distribution should be carried out under the condition that the joint surface and end surface are flush with the opening and closing surface and end surface of the relevant bearing hole. Do not loosen after the pin is driven in.
23. The bearing body of the spherical bearing should be in uniform contact with the bearing seat, and the contact should not be less than 70% by coloring method.
24. Alloy bearing bushings are not allowed to be used when the surface is yellow, and no nucleation is allowed within the specified contact angle, and the area of nuclei outside the contact angle must not exceed 10% of the total area of the non-contact area.
25. The reference end face of the gear (worm gear) should be in close contact with the shaft shoulder (or the end face of the positioning sleeve), and cannot be checked with a 0.05mm feeler gauge. And the perpendicularity requirements between the gear datum end face and the axis should be guaranteed.
26. The joint surface of the gearbox and the cover should be in good contact.
27. Strictly check and remove sharp angles, burrs and foreign objects remaining during part processing before assembly. Make sure that the seal is not scratched when it is installed.
casting requirements
1. Cold snaps, cracks, shrinkage cavities, penetrating defects, and serious incomplete defects (such as undercasting, mechanical damage, etc.) are not allowed on the surface of the casting.
2. The castings should be cleaned without burrs and flashes, and the risers on the non-processing surface should be cleaned flush with the surface of the castings.
3. The casting characters and marks on the non-machined surface of castings should be clearly identifiable, and the position and font should meet the drawing requirements.
4. The roughness of the non-machined surface of the casting, sand casting R, is not greater than 50μm.
5. Castings should be cleaned of sprues, flying spurs, etc. The residual amount of the gate riser on the non-processed surface should be leveled and polished to meet the surface quality requirements.
6. The molding sand, core sand and core bone on the casting should be cleaned.
7. For the inclined part of the casting, its dimensional tolerance zone should be arranged symmetrically along the inclined plane.
8. The molding sand, core sand, core bone, succulent, sticky sand, etc. on the casting should be smoothed and cleaned.
9. The right and wrong type, the casting deviation of the boss, etc. should be corrected to achieve a smooth transition and ensure the appearance quality.
10. Wrinkles on the non-machined surface of the casting, the depth is less than 2mm, and the spacing should be greater than 100mm.
11. The non-processed surfaces of castings of machine products need to be shot blasted or rolled to meet the requirements of cleanliness Sa2 1/2.
12. Castings must be water toughened.
13. The surface of the casting should be flat, and the gate, burr, sticky sand, etc. should be cleaned.
14. Castings are not allowed to have casting defects such as cold shuts, cracks, holes, etc. that are detrimental to the use.
Painting requirements
1. The surface of all steel parts that need to be painted must be free of rust, scale, grease, dust, mud, salt and dirt before painting.
2. Before derusting, use organic solvent, lye, emulsifier, steam, etc. to remove grease and dirt on the surface of steel parts.
3. The time interval between shot blasting or manual rust removal and priming shall not exceed 6 hours.
4. The surface of the riveted parts in contact with each other must be coated with anti-rust paint with a thickness of 30-40 μm before connection. Lap edges shall be closed with paint, putty or adhesive. Primer damaged by machining or welding shall be recoated.
Piping requirements
1. Before assembly, all pipe ends shall be deburred, deburred and chamfered. Use compressed air or other methods to remove debris and floating rust attached to the inner wall of the pipe.
2. Before assembly, all steel pipes (including prefabricated pipes) must be degreased, pickled, neutralized, washed and rust-proofed.
3. When assembling, tighten the pipe clamps, supports, flanges, joints and other parts that are fixed by threaded connections to prevent loosening.
4. The welded parts of the prefabricated pipes must be subjected to a pressure test.
5. When the piping is replaced or transferred, the separation port of the piping must be sealed with tape or plastic pipe plugs to prevent any debris from entering, and a label must be fastened.
Requirements for Repair Welding Parts
1. 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 shoveling, grinding, carbon arc gouging, gas cutting or mechanical processing.
3. Dirt such as sticky sand, oil, water and rust within 20mm around the welding area and groove must be thoroughly cleaned.
4. During the whole welding process, the temperature in the preheating zone of steel castings shall not be lower than 350°C.
5. If conditions permit, weld in a horizontal position as much as possible.
6. When repairing welding, the electrode should not swing too much laterally.
7. When surfacing 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 weld meat is full, and the welding surface has no burns, cracks and obvious nodules. The appearance of the welding seam is beautiful, without defects such as meat biting, slag addition, pores, cracks, and splashes; the welding wave is uniform.
Forging requirements
1. The nozzle and riser of the ingot should have enough cut off to ensure that the forging has no shrinkage cavity and serious deflection.
2. The forging should be forged on a forging press with sufficient capacity to ensure that the inside of the forging is fully forged.
3. Forgings are not allowed to have visible cracks, folds and other appearance defects that affect the use. Local defects can be removed, but the cleaning depth should not exceed 75% of the machining allowance, and the defects on the non-machined surface of the forging should be cleaned up and transitioned smoothly.
4. Forgings are not allowed to have white spots, internal cracks and residual shrinkage cavities.
Cutting parts requirements
1. Parts should be inspected and accepted according to the process, and can only be transferred to the next process after passing the inspection of the previous process.
2. The processed parts are not allowed to have burrs.
3. The finished parts should not be placed directly on the ground when they are placed, and necessary support and protection measures should be taken. Defects such as rust, moth, bumps and scratches that affect performance, life or appearance are not allowed on the processed surface.
4. Roll the finished surface, and there must be no peeling after rolling.
5. There should be no scale on the surface of parts after heat treatment in the final process. Finished mating surfaces and tooth surfaces should not be annealed
6. The surface of the processed thread is not allowed to have defects such as black skin, bumps, chaotic buckles and burrs.
