Influence of accuracy characteristics of machine tool on large gear error

From the configuration principle, the accuracy characteristics of such machine tools can be obtained:

① The tooth profile error is composed of contact trace error and helix error. Because the hob and the workpiece have the same relative position on the starting line, the error of each contact trace on each helix is the same. For example, the error of each contact trace with the same size and symbol on the starting line is the same on the helix of tooth top and tooth root.

② The tooth direction error mainly depends on the accuracy of the differential chain of the machine tool and the adjustment of the intersection angle between the interference hob and the workpiece. Referring to the above discussion, the contact trace error generally does not affect the tooth alignment error. The differential chain error is mostly periodic, so it often causes the periodic error of tooth direction. If there is a constant error in the tooth direction, that is, the helix angle is too large or too small, it is often caused by the adjustment error of the staggered angle.

③ Tooth profile error is the synthesis of contact trace error and helix error. As mentioned above, this kind of machine tool directly processes the contact trace rather than the involute. Therefore, the involute tooth profile of each section will be constructed by many contact traces, and its error is the combination of contact trace error and helix error. If the influence of helix error is ignored, and the size of contact trace error on each helix is the same, so the size and phase of tooth profile error curve drawn on each section in the tooth width direction are the same, that is, the consistency of tooth profile error is good.

④ The contact trace error and helix error will directly cause the straight generatrix error of the tooth surface.