Spiral groove of automobile gear hob

The groove type of automobile gear hob is divided into straight groove and spiral groove. The straight groove is very convenient for users to grind again. When the lead angle is very small, the straight groove will only cause a small change in the tooth profile. If the lead angle is large enough to have a great impact on the tooth profile, the spiral groove will be a normal angle for the tooth direction. When the lead angle is less than 4 °, the tooth direction angle of automobile gear hob is usually ignored, that is, the form of straight groove is adopted.

The number and width of spiral grooves are determined by the diameter and full tooth depth of automobile gear hob. The width of spiral groove shall ensure enough chip holding groove and grinding space of grinding wheel. For most standard direct automotive gear hobs, the number of chip holding grooves can basically ensure the normal grinding and use of the tool. When a larger chip holding groove is required, the standard diameter of automobile gear hob will generally be increased.

All standard and most special automobile gear hobs adopt 0 ° rake angle. However, the rake face of some automotive gear hobs will also be designed into positive rake angle and negative rake angle. These requirements are based on special working conditions. The positive rake angle is sharper for ordinary cutting, while the negative rake angle automobile gear hob is more limited.

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