Most of the inherent accuracy of the gear hob can be destroyed. Therefore, if the tolerance of tooth profile is very small, the diameter jump of automobile gear hob must be strictly controlled. First of all, the jumping of automobile gear hob leads to out of tolerance of tooth profile, and all teeth of automobile gear hob cannot be cut at the required position. For multi head hobs and even three head hobs, runout can produce tooth thickness change and tooth profile deviation. The inspection method of runout of automobile gear hob will be described in detail later.
In order to facilitate the calibration of hobs on the cutter shaft of automobile gear hobbing machine, all hobs will have a plane with the assembly center for inspection. There are two planes, which are located on both sides of the hob, and are machined on the same benchmark as the hob teeth of automobile gear.
Before the automobile gear hob is installed on the mandrel, the runout on the mandrel must be checked first. Checking with a dial indicator ensures that the spindle is OK. This inspection must be carried out on the support without bearing. If it is necessary to loosen it, only use the terminal for support. The dial indicator shall be less than 0.005mm on all sections of the mandrel. The same inspection procedure is also applicable to rod hobs.
Similarly, the automobile gear hob should also be checked with a dial indicator. Fix the automobile gear hob to be checked on the tool bar. For taper hole hobs, the torque of the fastening nut should be repeatedly practiced and verified, and it can’t be too tight or too loose. Select appropriate anti loose gasket and nut to ensure that the nut will not be loosened easily.