Parametric Design And Dynamic Contact Characteristics Research Of Involute Worm Gears

Involute worm drive has the virtue of high bearing capacity, silent running,high transmission efficiency and longevity of service, and has obtainedextensiveapplication in the national defense and civil industry. The fatigue wear and contactperformance of involute gears has a strong impact on the whole machineperformance. Based on the worm meshing principle, contact dynamics theory andthe actual work condition, the parametric design, friction and wear, dynamiccontact characteristics of the involute worm gears are researched in this paper. Themain work can be summarized as follows:(1) The equations of the involute worm gears’ tooth surfaces and contact linesare derived according to the space engagement theory. A mathematical model iscreated based on the equation of the worm gear’s tooth surface, and a series ofpoints on the surface are calculated by Matlab, in the CATIA reverse engineeringmodule, the surface of tooth is constructed by these points, and then the accurategeometric model of worm gear is created. Assemble the model with the worm, thereis no interference occurs, it can be applied to the dynamics simulation and finiteelement analysis. The modeling method provide a reference for the accuratemodeling of other complex institutions and surface.(2) Make the involute worm as an object, by the skeleton modeling method,first define the parameter variables, then create all the geometric elements, lastestablish an entity, the involute worm’s parameterized secondary developmentprogram is completed in the CATIA platform. By inputting the basic parameters ofthe worm in the development interface, the program automatically performsparameter calculation, graphics rendering, Boolean operations and generate thegeometric model of the worm eventually, which provides a convenient for themotion simulation, CNC machining and finite element analysis of the worm gears,also provides a guide for the secondary development of other parts.(3) For fatigue wear failure of the worm drive, the friction and wear experiments ofthree groups of worm gears’ materials are performed in the paper. The friction coefficient,abrasion loss, form of wear are researched in the experiment. By experimentalcomparison: the friction coefficient and abrasion loss between ZQSn10-1and42CrMo(nitride) are minimum. There is no necessary link between the friction coefficient and abrasion loss, the value of friction is greater, the abrasion loss may not be greater.From the wear surface morphology, the abrasive wear is the main forms of wear andtear. Select the optimal performance of a group of materials to dynamic contactanalysis of the worm gears.(4) A method of contact dynamic finite element analysis is introduced. In thisway, an accurate involute worm pair is created by HyperMesh, ANSYS/LS-DYNAis used as solver, the tooth contact-stress, tooth strain, regularity of engagement arestudied in the process of a tooth rotation time of the worm gear under the conditionof the maximum speed-torque output. The result shows that tooth-surface stressdecreases gradually as the meshing of teeth increase, elastic deformation occurs in thiscondition which is checked by Mises criterion. In each moment of the engagement, themaximum stress of worm and worm gear is close to, but the maximum strain always occursin the worm wheel.