First : blank inspection
Before processing, first understand the material of the blank, the state after forging (generally the tempered state, refer to the material certificate of the forging certificate). Secondly, it is necessary to check whether the blank has defects such as lamination and cracks. Measure the dimensions of the blank. The inner and outer diameters of the blank, the height dimension, and the machining allowance are measured, and the number of times of turning in the turning process is accurately estimated.
Second: turning processing
1) Roughing: Roughing according to the turning process drawings, the cutting speed and cutting amount are strictly in accordance with the process regulations (the general cutting speed is 5 rev / min. The cutting amount is 10mm ~ 12mm).
1.jpg2) Roughing aging: After the roughing of the bearing parts is completed, the three-point support and flat release (not allowed to stack) are used, and the aging time is not less than 48 hours before the finishing of the car can be performed.
3) When the precision bearing parts are finished, the cutting speed is 6 to 8 revolutions per minute, and the cutting amount is 0.3 to 0.5 mm.
4) Molding finishing car: When the bearing parts are finally formed into the finished car, in order to prevent the parts from being deformed, the fixed clamping device of the parts must be loosened to make the parts in a state of no stress. The turning speed is 8 revolutions per minute and the cutting amount is 0.2 mm. .
5) Cross-three-row roller slewing bearing inner ring special process: to prevent deformation of the inner ring of the cross-row and three-row roller slewing bearing after heat treatment. When turning, it is necessary to perform pair processing, that is, the back-to-back processing of the raceway, without cutting before heat treatment, and cutting after heat.
6) After finishing the heat: After the heat treatment of the inner and outer rings of the bearing, the finishing procedure and the technical procedure are the same as 2.3 and 2.4.
Third: heat treatment
1) Quenching surface quenching: 2.jpg bearing raceway surface medium frequency quenching, hardness not less than 55HRC, hardened layer depth not less than 4mm, soft belt width less than 50mm, and marked “S” in the corresponding place. (Sometimes customers can request carburizing, nitriding, carbonitriding, etc.)
2) After heat tempering treatment: After the intermediate frequency quenching of the inner and outer rings of the bearing, it must be baked at 200C for 48 hours. To ensure the disappearance of internal stress.
Fourth: rolling, milling processing
For the slewing bearing with internal and external teeth, the hobbing process should be carried out before the grinding process, and the processing should be strictly in accordance with the process requirements, and the accuracy level should reach 8 or more.
1) Marking: After measuring the dimensions of the parts, the lines are scribed and positioned according to the specified dimensions of the drawings. The holes shall not differ by more than 3%.
2) Drilling: Check the size of the scribe line against the drawing to ensure the correct size and then carry out the drilling process. The mounting hole of the slewing bearing of the inner body should be combined and processed, and the error of the hole spacing of the soft band between 180C degrees should not exceed 5%.
Sixth: Grinding processing
1) Rough grinding: using medium corundum, soft three-grain degree of 36 degrees, grinding with atmospheric pore resin grinding wheel, the line speed is controlled at 1500 rpm, to prevent raceway burn. The maximum grinding depth must not exceed 1 mm.
2) Fine grinding: grinding with a particle size of 46 degrees or 60 degrees resin grinding wheel, the grinding amount is less than the rough grinding process, and the finish should reach the level specified in the drawings.
Seventh: assembly, inspection documents
1) Formulation clearance: After the grinding process, the test assembly should be carried out to measure the initial clearance. According to the calculation data and the test clearance, the final grinding process is carried out, and the final drawing specifies the clearance. 2.jpg
2) Parts inspection: After the clearance is completed, the final part inspection should be carried out and recorded accordingly.
3) Demagnetization, cleaning, packaging and issuing a certificate.
In order to provide users with a better understanding of the technical parameters such as the intrinsic quality of the slewing bearing and the material source, the following technical information is provided:
- Circulating bearing certificate.
- Installation instructions for the slewing bearing.
- Bearing parts material certificate (material book).
- Rolling body flaw detection report.
- Bearing heat treatment certificate.