Research On Improving The Strength Of Coal-Cutter's Pin Gear

Pin gear can be used to transmit torque and drive the coal-cutter. It is one of the important parts of coal-cutter, thus its life-span will directly influence the coal-cutter's working efficiency. The average life of pin gears of domestic high-power coal-cutters is less than three months, so the research on improving the pin gear strength has great importance in production. This paper attempts to improve the pin gear structure from two aspects in order to enhance the contact strength of tooth surface and the bending strength of tooth root.Firstly, by doing loading analysis of coal shearer and its walking device, this paper tries to figure out the pin gear's load situation in its working, then find out the reason of load-excursion that can easily happen in the pin gear, and analyse the pin gera failure form led by this. In order to solve this problem, the paper proposes the method of doing tooth profile modification on the pin gear. According to the Hertz theory, the contacting force between pin gear and the conveyor rail is analyzed, and the modification method and value are confirmed theoretically.Secondly, the formation of tooth profile of the pin gear is analyzed. Based on the epicycloid, hypocycloid and involute formation theories, the combind tooth profile is made up of the epicycloid above the pitch circle and the involute below the pitch circle. The form and formation of transition curve between the epicycloid and the involute are proposed.And then, finite element method is used to analyze the involute tooth profile pin gear and the combind tooth profile pin gear. The tooth profile 3D models of these two pin gears'are separately created in Pro/E, and based on these 3D models, the loading analysis is carried out by ANSYS.Finally, through the comparison analysis of the study results, the pin gear contact situation can be greatly improved and the contact strength of tooth profile and the bending strength of tooth root can be enhanced by modifying the tooth surface of pin gear, using the combind tooth profile and employing the appropriate tooth profile transition curve.