After the spiral bevel gear is processed under given grinding conditions, the tooth surface has no obvious defects such as grinding crack or grinding burn. In order to verify the influence of grinding parameters on surface quality, we have made another reference group of maximum cutting depth, in which the process parameters are grinding depth AP = 0.20 mm, grinding speed vs = 30 m / s and gear generation speed w = 14 ° / s. Sparks are generated during machining. At this time, the machine tool has started to alarm due to the protection mechanism, but there is still no grinding damage on the tooth surface. The cleaned tooth surface is shown in Figure 1. This is due to the good lubrication and cooling performance of grinding fluid and the good cutting performance of SG grinding wheel. According to the actual processing and production experience, the grinding burn phenomenon in the grinding link is caused by improper control of heat treatment link and excessive deformation error. If the grinding process parameters are within the specified range, the thermal treatment parameters will not be damaged in general.
After that, the tooth samples cut by wire cutting are cleaned by ultrasonic cleaning machine, and then placed under Kearns laser microscope to observe the micro morphology of tooth surface under different parameter combinations. The results are shown in Figure 2.
It can be seen from (a) and (b) in Figure 2 that when other parameters are fixed, with the reduction of grinding speed, the grinding tooth surface is relatively coarser and the number of surface pits is relatively large. The main reason for the formation of pits is that the abrasive particles fall off and are embedded on the surface of the substrate during grinding. With the decrease of grinding speed, the sliding and extrusion effect of abrasive particles increases, and the phenomenon of abrasive particles fall off and embedded on the substrate is more obvious, resulting in the deterioration of surface quality.
It can be seen from (a) and (c) in Figure 2 that the grinding depth also has a significant impact on the quality of the machined surface. When the cutting depth is too large, on the one hand, the pits formed by the abrasive particles falling off and embedded on the substrate surface increase, on the other hand, the increase of the grinding depth will increase the undeformed thickness of a single abrasive particle in the grinding area, and the groove depth and uplift on both sides of the abrasive particles on the workpiece will be more obvious than that in the case of small cutting depth, resulting in rough and uneven grinding surface, The surface roughness increases significantly.
Therefore, according to the above experimental research on the grinding tooth surface morphology of spiral bevel gear, it can be seen that in the grinding process, the grinding speed should be increased as far as possible within the range of no grinding damage on the tooth surface, and the grinding depth should be reduced on the premise of ensuring the production efficiency, so as to obtain an excellent grinding tooth surface morphology of spiral bevel gear.