Analysis and improvement of the processing technology of the semi-axle gear
At present, there are roughly two kinds of processing processes for the differential half shaft gear machine:
1 qualified fine forging blank → cold trimming → shot blasting → drilling → small end face, inner hole → outer circle, mounting surface, back cone → broaching internal spline → heat treatment → grinding outer circle, mounting surface.
The main process in Process 1 is shown in Figure 4.
Drilling--small end face, inner hole--outer round, mounting surface, back cone--grinding outer circle, mounting surface
2 qualified precision forging blanks → shot blasting → small end face, outer circle, mounting surface, back cone → cold trimming → drilling, inner hole → broaching internal spline → heat treatment → grinding outer circle, mounting surface.
Small end face, outer circle, mounting surface, back cone--drilling, inner hole--grinding outer circle, mounting surface
Comparing the hot front and hot post-processing of the above two half-shaft gears, it can be seen that there are many hot pre-processes in Process 1, which leads to more processing equipment, more manpower, and difficult quality control.
The thermal finishing process in the two processes is literally not different, but it can be seen from the process diagram that the fundamental difference between the two is that the positioning criteria are different during processing.
Process 1 is based on internal spline key side positioning and grinding. The manufacturer who executes the process is only to meet the requirements of the pattern and to meet the mechanical behavior of the axle manufacturer according to the acceptance of the figure. There is no working principle from the differential. The short-term behavior of the working state of the gear and the transmission force and torque are carefully analyzed. The internal spline of the semi-axle gear is matched with the external spline of the axle of the car. It is a clearance fit, which only transmits the torque generated by the different angular speeds of the two axles of the two axles caused by the left and right wheels turning.
If it is mechanically copied according to the user's pattern, in order to cope with the internal spline as the reference, the detection of the end face, the end of the outer circle, and the radial runout are bound to be deformed by the spline of the internal spline (in view of the current domestic raw materials, quenching oil) And the current state of the quenching process, the heat treatment spline deformation is difficult to obtain effective and stable control as in foreign countries) and weaken the control of the ring gear.
In addition, the thermal post-processing method of the internal spline positioning expansion is often caused by the different deformation of the internal spline and the irregular shape, so that the taper and the ellipticity of the spline hole are different, and the gear of the component is in the taper spline shaft. The axial position of the upper part is different, and the height of the gear mounting surface which is ground is also large, so that the installation distance of the same batch of the semi-axle gear is extremely unstable. The axial gap of the assembled differential assembly half shaft gear is unstable, and the point card phenomenon and the large gap during the rotation process often occur, so that the assembly workers on the assembly line frequently change the adjustment gasket and affect the assembly efficiency. Or when the assembly is negligent, it is not found that the gap is too large, which will cause the differential to rotate abnormally, resulting in the final disassembly of the assembly.
In the process 2, the toothed shape is positioned, the small end face is pressed, the mounting surface and the outer circle are ground, and the perpendicularity or the end face of the mounting surface relative to the outer cylindrical journal is easily ensured, and the outer circle and the mounting surface are The reference, the anti-measuring bevel gear tooth ring runout, is also easier to control within 0.08mm, which is a good guarantee of the special characteristics of the bevel gear outer circle, mounting surface, tooth shape and other geometric tolerances, The detection standard is finally unified with the final comprehensive detection of the gear, that is, based on the outer circle and the mounting surface of the half-shaft gear, and the inner hole and the spherical surface of the planetary gear are used as the reference, and the above-mentioned rolling is checked on the bevel gear special comprehensive detector. The detection range of the installation distance of a pair of gears, the size of the side gap, the size and position of the contact area of the tooth surface, and the like are similar to the actual reproduction of the assembly, detection and working state in the differential housing.
This basically realizes the uniformity of the positioning reference, the detection reference and the assembly reference or the working reference during the processing of the differential bevel gear, which is beneficial to improve the machining accuracy of the gear and avoid the loss of precision caused by the reference conversion, thereby improving the use of the gear. life.
