Summary of technical requirements for machining mechanical parts
First, the contour processing of parts.
1, unannotated shape tolerance should be in line with the requirements of GB1184-80.
2, not note the length of the size of the allowable deviation ± 0.5 mm.
3, not noted rounded corner radius R5.
4, not noted chamfer are C2.
5.Sharp corner chamfering blunt.
6.Sharp edge chamfering blunt, remove burr flying edge.
Second, the surface treatment of the parts.
1.On the machined surface of the parts, there should be no scratches, abrasions and other defects that damage the surface of the parts.
2, the machined thread surface should not be allowed to have defects such as black skin, bump, messy buckle and burr.
Before painting, all steel parts must be free of rust, oxide, grease, dust, mud, salt and dirt.
3.Before removing rust, remove grease and dirt from the surface of steel parts with organic solvent, alkali, emulsifier, steam, etc.
4.The time interval between the surface to be coated by shot blasting or manual rust removal and the primer coating shall not be more than 6h.
5, riveted parts in contact with each other's surface, before connecting must be coated with a thickness of 30 ~ 40μm anti-rust paint. The edge of the lap joint should be closed with paint, putty or adhesive. The primer damaged due to processing or welding should be repainted.
Third, the heat treatment of parts.
1, by tempering treatment, HRC50 ~ 55.
2, medium carbon steel: 45 or 40Cr parts for high-frequency quenching, 350 ~ 370 ℃ tempering, HRC40 ~ 45.
3, carburizing depth of 0.3mm.
4.High-temperature aging treatment.
Fourth, after finishing technical requirements
1, after finishing parts shall not be placed directly on the ground, should take the necessary support, protection measures. 2, processing surface does not allow rust and affect the performance, life or appearance of the bump, scratch and other defects.
3, rolling finishing surface, after rolling shall not have peeling phenomenon.
4, the final process after heat treatment of the parts, the surface should not have oxide skin. After finishing with the surface, the tooth surface should not be annealed
V. Sealing treatment of parts.
1, each seal must be soaked in oil before assembly.
2, assembly before strict inspection and removal of parts processing residual sharp corners, burrs and foreign objects. Ensure that the seals are not scratched when they are installed.
3.After bonding, the excess adhesive should be removed.
Sixth, gear technical requirements.
1.After gear assembly, the contact spots and side gaps of the tooth surface should conform to the provisions of GB10095 and GB11365.
2, gear (worm wheel) benchmark end face and shaft shoulder (or positioning sleeve end face) should fit, with 0.05mm plug gauge check does not enter. And should ensure that the gear benchmark end face and axis perpendicularity requirements.
4.The combination surface of gear box and cover should be in good contact.
Seventh, casting technical requirements.
1, the casting tolerance zone symmetry in the basic size configuration of the blank casting.
2, the casting surface does not allow cold partition, cracks, shrinkage and penetrating defects and serious defects in the category of defects (such as under-casting, mechanical damage, etc.).
3.Castings should be cleaned up, no burrs, flying edge, non-machining indicates that the sprue should be cleaned up flush with the surface of the casting.
4, castings on the non-machined surface of the castings and signs should be clear and legible, the location and font should be in line with the requirements of the drawings.
5, the roughness of the non-machined surface of the casting, sand casting R, not more than 50μm.
6, castings should be cleared of sprues, flying spurs, etc. The residue of the sprue on the non-machined surface should be leveled and polished to meet the surface quality requirements.
7.Castings on the sand, core sand and core bone should be cleared.
8, the casting has an inclined part, its size tolerance zone should be along the inclined side of the proportional configuration.
9, castings on the type of sand, core sand, core bone, succulent, sticky sand, etc. should be shovel grinding smooth, clean up.
10, the wrong type, tab casting deviation, etc. should be corrected to achieve a smooth transition, a guarantee of appearance quality.
11.The wrinkles on the non-machined surface of the casting, the depth is less than 2mm, and the spacing should be more than 100mm.
12, machine products castings of the non-machined surface are required to be shot peening or roller treatment, to achieve the requirements of cleanliness Sa2 1/2 level.
13.Castings must be treated with water toughness.
14.The surface of the casting should be flat, and the sprue, burr and sticky sand should be cleared.
15.Castings are not allowed to have cold partition, cracks, holes and other casting defects that are detrimental to use.
Eighth, forgings technical requirements.
1.Each ingot should have sufficient removal amount of spout and riser, one to ensure that the forgings are free of shrinkage and serious deflection.
2, forgings should be forged in the forging press with sufficient capacity to ensure that the forgings are fully forged inside.
3, forgings are not allowed to have cracks, folding and other defects that affect the appearance of use visible to the naked eye. Local defects can be removed, but the cleaning depth shall not exceed 75% of the machining allowance, and the defects on the non-machined surface of the forging shall be cleaned up and rounded transition.
4, forgings do not allow the existence of white spots, internal cracks and residual shrinkage.