Analysis of 20CrMnTi tooth surface roughness based on Gear Hobbing

In recent years, the machining of mechanical parts is developing in the direction of intelligence and efficiency. With the increasing complexity of machining materials, the technical requirements for machining parts are higher and higher. The research shows that the tooth surface roughness has an impact on the contact fatigue stress in gear transmission. The greater the tooth surface roughness value, the faster the wear during transmission. The small pits caused by severe wear on the tooth surface lead to stress concentration and reduce the fatigue life of the gear. At present, most of them study how to improve the machining accuracy of hobbing, but there are few studies on the influencing factors of tooth surface roughness. Li linkun mainly studied how to improve the gear hobbing machining accuracy and surface accuracy from the aspects of gear blank machining quality and the accuracy of gear hobbing fixture. Zhao Han and others mentioned the factors and control methods affecting the gear hobbing surface roughness in the cause analysis of shaft gear machining accuracy. These studies did not fully and deeply analyze the causes affecting the gear hobbing surface roughness. This paper will study the hob surface quality, top edge fillet radius and edge shape, comprehensively analyze and verify the influence of gear hobbing on gear surface roughness, so as to provide a reference basis for improving the surface quality of gear hobbing parts in subsequent actual machining.

The influencing factors of gear surface roughness in gear hobbing are analyzed and studied. Through three experiments, the following conclusions are obtained:

1) Higher hob rake face quality makes it easier to get smaller gear surface roughness in gear hobbing. In the later hobbing process, the surface quality of gear parts can be improved by reasonable grinding or new tool surface treatment technology.

2) Under the condition of no transition interference in gear hobbing, large fillet radius of hob top edge can obtain high gear surface quality in machining. The fillet radius of the top edge of the hob shall not be too small, which will aggravate the wear and reduce the service life of the hob.

3) Different hob edge shapes have a great influence on the tooth surface roughness. When hobbing, the surface quality of gear parts obtained by using large edge arc hob is better than that of small hob. The research results can lay a foundation for the research on the cross influence of multiple factors in gear hobbing in the later stage.

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