Encyclopedia Of Mechanical Processing Technology Requirements, Necessary Information For Mechanical Practitioners

General technical requirements

1. Deoxidize the parts.

2. On the processed surface of the part, there should be no scratches, scratches and other defects that damage the surface of the part.

3. Remove burr and flash.

Heat treatment requirements

1. After quenching and tempering, HRC50～55.

2. The parts are subjected to high-frequency quenching, tempering at 350～370℃, HRC40～45.

3. The carburizing depth is 0.3mm.

4. Carry out high-temperature ageing treatment.

Tolerance requirements

1. Unmarked shape tolerances should meet the requirements of GB1184-80.

2. The allowable deviation of the unmarked length dimension is ±0.5mm.

3. The casting tolerance zone is symmetrical to the basic size configuration of the roughcasting.

Part edges and corners

1. No fillet radius R5.

2. All unfilled chamfers are 2×45°.

3. Sharp corners/sharp corners/sharp edges are blunt.

Assembly requirements

1. All seals must be soaked in oil before assembly.

2. Assembling rolling bearings, it is allowed to use oil heating for hot charging, and the temperature of the oil should not exceed 100°C.

3. After the gear is assembled, the contact spots and backlash on the tooth surface should meet the requirements of GB10095 and GB11365.

4. When assembling the hydraulic system, it is allowed to use packing or sealant, but it should be prevented from entering the system.

5. The parts and components (including purchased parts and outsourcing parts) that enter the assembly must have the certificate of the inspection department before they can be assembled.

6. The parts must be cleaned up and cleaned before assembling, and there must be no burrs, flashes, oxide skin, rust, chips, oil stains, colourants and dust.

7. Before assembling, recheck the main matching dimensions of parts and components, especially the interference fit dimensions and related accuracy.

8. The parts are not allowed to knock, bump, scratch and rust during the assembly process.

9. When tightening screws, bolts and nuts, it is strictly prohibited to strike or use inappropriate screwdrivers and wrenches. The screw grooves, nuts and screws, and bolt heads shall not be damaged after tightening.

10. The fasteners with specified tightening torque must be tightened with a torque wrench and tightened according to the specified tightening torque.

11. When the same part is fastened with multiple screws (bolts), each screw (bolt) needs to be tightened crosswise, symmetrically, gradually and evenly.

12. When assembling the tapered pin, the hole should be painted and checked, and the contact rate should not be less than 60% of the mating length and should be evenly distributed.

13. The flat key should be evenly in contact with the two sides of the keyway on the shaft, and there should be no gap between the mating surfaces.

14. The number of tooth surfaces that are in contact with the 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 the length and height of the key teeth.

15. After the flat key (or spline) with sliding fit is assembled, the relative parts can move freely without uneven tightness.

16. After bonding, the excess adhesive should be removed.

17. The semicircular holes of the outer ring of the bearing, the open bearing seat and the bearing cover are not allowed to jam.

18. The outer ring of the bearing should be in good contact with the semi-circular hole of the open bearing seat and the bearing cover. When checking with colouring, it should be symmetrical with the bearing seat at 120° to the centerline and with the bearing cap within the range of 90° symmetrical to the centerline. Even contact. When inspecting 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 should contact the end face of the bearing cap at the positioning end evenly.

20. After the rolling bearing is installed, it should be flexible and stable to rotate by hand.

21. The joint surfaces of the upper and lower bearing bushes should be closely attached to each other, and they cannot be checked with a 0.05mm feeler gauge.

22. When fixing the bearing bush with locating pins, drill the reaming and distributing pins while ensuring that the opening and closing faces and end bread of the bushing surface and the end face of the relevant bearing hole are flush with each other. Do not loosen the pin after driving in.

23. The bearing body of the spherical bearing and the bearing seat should be in uniform contact, and the contact should not be less than 70% when inspected by the colouring method.

24. Alloy bearing linings are not allowed to be used when the surface is yellow, and the nucleation is not allowed within the specified contact angle, and 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) and the shaft shoulder (or the end face of the positioning sleeve) should fit together and cannot be checked with a 0.05mm feeler gauge. And should ensure the verticality requirements of the reference end face of the gear and the axis.

26. The joint surface of the gearbox and the cover should be in good contact.

27. Strictly check and remove the sharp corners, burrs and foreign objects remaining during the processing of the parts before assembly. Ensure that the seal is not scratched when it is installed.

Forging requirements

1. The nozzles and risers of the ingot should be sufficiently removed to ensure that there is no shrinkage and serious deflection of the forging.

2. The forging should be forged on a forging press with sufficient capacity to ensure that the forging is fully penetrated.

3. Forgings are not allowed to have visible cracks, folds and other appearance defects that affect use. Local defects can be removed, but the cleaning depth should not exceed 75% of the machining allowance. The defects on the non-machined surface of the forging should be cleaned and smoothly transitioned.

4. White spots, internal cracks and residual shrinkage holes are not allowed in forgings.

Cutting parts requirements

1. The parts should be inspected and accepted according to the procedure and can be transferred to the next procedure only after the previous procedure has passed the inspection.

2. The processed parts are not allowed to have burrs.

3. The finished parts shall not be placed directly on the ground when placed, and necessary support and protection measures shall be taken. The processed surface is not allowed to have defects such as rust, bumps and scratches that affect performance, life or appearance.

4. The surface finished by rolling shall not peel off after rolling.

5. There should be no oxide scale on the surface of the 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, random buckles and burrs.