CNC Machining · 2021年5月7日

Encyclopedia of mechanical drawings and technical requirements, the collection of the first

General technical requirements

1. Remove the oxide scale of the parts.

2. There should be no scratches, abrasions and other defects that damage the surface of the part on the processed 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 aging 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 rough casting.

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. The assembly of rolling bearings 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 seal 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 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 scales, rust, chips, oil stains, colorants and dust.

7. The main matching dimensions of parts and components, especially the interference fit dimensions and related accuracy should be rechecked before assembly.

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 forbidden 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 the 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), the screws (bolts) must 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 in uniform 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, remove the excess adhesive flowing out.

17. The semi-circular 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 semicircular hole of the open bearing seat and the bearing cover. When checking with coloring, 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 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 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 of the bushing surface and the end face of the relevant bearing hole and the end bread are flush. 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 coloring method.

24. Alloy bearing linings are not allowed to be used when the surface is yellow, and 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) 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 gear box 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.

Casting requirements

1. No cold partition, cracks, shrinkage holes, penetrating defects and serious incomplete defects (such as under-casting, mechanical damage, etc.) are allowed on the surface of the casting.

2. The castings should be cleaned up without burrs and flashes. The pouring risers on the non-processing indications should be cleaned and flush with the surface of the castings.

3. The casting characters and marks on the non-machined surface of the casting should be clear and identifiable, and the position and font should meet the requirements of the drawing.

4. The roughness of the non-machined surface of the casting, sand casting R, is not more than 50μm.

5. Castings should be clear of pouring risers, spurs, etc. The remaining amount of the pouring 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. The castings have inclined parts, and the 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 castings should be smoothed and cleaned up.

9. Correct and wrong type, boss casting deviation, etc. should be corrected to achieve a smooth transition and ensure the appearance quality.

10. The wrinkles on the non-machined surface of the casting should have a depth of less than 2mm, and the spacing should be greater than 100mm.

11. The non-processed surface of the machine product castings needs to be shot peened or roller processed to meet the requirements of the cleanliness Sa2 1/2 level.

12. The casting must be water toughened.

13. The surface of the casting should be smooth, and the gate, burr, sticky sand, etc. should be removed.

14. Castings are not allowed to have casting defects such as cold partitions, cracks, holes, etc. that are detrimental to use.

Painting requirements

1. Before painting the surface of all steel parts that need to be painted, rust, oxide scale, grease, dust, soil, salt and dirt must be removed.

2. Before rust removal, use organic solvents, lye, emulsifier, steam, etc. to remove grease and dirt on the surface of steel parts.

3. The time interval between shot blasting or manual derusting of the surface to be coated and primer coating should not be more than 6h.

4. The surfaces of the riveting parts in contact with each other must be painted with a thickness of 30-40μm anti-rust paint before connecting. The lap edges should be sealed with paint, putty or adhesive. The primer damaged by processing or welding must be repainted.


Piping requirements

1. Before assembling, all pipes should be free of flashing, burrs and chamfering. Use compressed air or other methods to remove debris and rust attached to the inner wall of the pipe.

2. Before assembly, all steel pipes (including prefabricated pipes) must be degreased, pickled, neutralized, washed with water and rust-proof.

3. When assembling, tighten the pipe clamps, supports, flanges and joints to prevent loosening.

4. The welded parts of the prefabricated pipe must be subjected to a pressure test.

5. When piping is replaced or transferred, the separation port of the pipeline must be sealed with tape or plastic pipe to prevent any debris from entering, and label it.

Repair weldment requirements

1. Defects must be thoroughly removed before welding, and the groove surface should be repaired smoothly and without sharp corners.

2. According to the defects of the steel castings, the defects in the welding zone can be removed by shoveling, grinding, carbon arc gouging, gas cutting or mechanical processing.

3. The dirt, sand, oil, water, rust and other dirt within 20mm around the welding area and the groove must be thoroughly cleaned up.

4. During the whole welding process, the temperature of the preheating zone of the steel castings shall not be lower than 350°C.

5. When conditions permit, weld as much as possible in a horizontal position.

6. When repairing welding, the welding rod should not make excessive lateral swing.

7. When surfacing welding on the surface of steel castings, the overlap between the weld beads shall not be less than 1/3 of the weld bead width. The welding meat is full, and the welding surface is free of burns, cracks and obvious nodules. The welding seam has a beautiful appearance, and has no defects such as meat biting, slagging, pores, cracks, and splashes; the welding wave is uniform.

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. Forgings should be forged on a forging press with sufficient capacity to ensure that the forgings are fully forged.

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 machined 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.​