1. Cutter compensation heat treatment distortion
The tooth profile of hypoid gear is complex, which has the problems of difficult tooth surface correction, large heat treatment distortion, high grinding cost and low efficiency. In the actual production process, the quality control of the contact area in the heat treatment stage is particularly important. According to the principle of contact zone offset and the distortion law of heat treatment, we cut the teeth inversely to the spiral angle of the concave surface of the tooth before heat treatment, and use the cutting teeth to compensate the distortion of heat treatment. After several trial cuts, a new tooth model is obtained, so that the spiral angle error of the concave surface of the tooth after heat treatment is controlled within – 6 ‘, so as to ensure that the contact area is located at the reasonable position of the middle and small end after heat treatment.
2. Verification of tooth surface error after cutting compensation heat treatment
In order to further test whether the tooth surface error of the model after heat treatment meets the expected requirements, the trial production is carried out according to the new gear cutting model, and 360 gears in the same cutter head processing cycle are sampled and inspected with 350gmm. First number 360 gears, and then perform gear cutting in sequence. The sampling inspection method adopted is: the first 5 pieces, the last 5 pieces and one piece every 20 pieces in the middle. Among them, the main teeth are marked as A1, A2, A3, A4, A5, A20, a40,…, A340, A356, A357, a358, a359 and a360 in sequence according to the gear cutting processing sequence, with a total of 27 pieces; The teeth to be cut are marked as B1, B2, B3, B4, B5, B20, b40,…, b340, b356, b357, b358, b359 and b360 in turn according to the cutting sequence, with a total of 27 pieces. Put the sampled samples of the driving and passive teeth into the rack separately for heat treatment processing. After processing, conduct 350gmm tooth surface error detection for the sampled driving and passive teeth, and obtain the tooth surface error detection results as shown in Figure 1.
According to the analysis of the tooth surface error detection results after heat treatment in Figure 1, after the cutting teeth are adjusted reversely to compensate the abnormal variables after heat treatment, the concave helix angle error after heat treatment of the tooth is roughly distributed in the range of – 6 ‘~ – 4’, which meets the expected requirements.
3. Verification of contact area after cutting compensation heat treatment
In order to further test whether the contact area of the model after heat treatment meets the expected requirements, select the main teeth after heat treatment and the teeth with helix angle error of concave surface after heat treatment of – 6 ‘, – 5’, – 4 ‘respectively for roll inspection on 600htt. The results are shown in Figure 7, and the specific change trend of the contact area.
By observing Fig. 2, it can be clearly found that after the cutter is reversely adjusted to compensate the distortion of heat treatment, the concave contact area of the tooth is separated from the small end area after heat treatment and located at the middle to small end, which meets the expected requirements.