The Research On CAD Prototype System For The Plane Double-enveloping Worm-gear Reducer

In order to improve the level of automation design for the plane double-enveloping worm- gear reducer, this paper developed a CAD prototype system for the reducer. TheCAD prototype system included two parts: 1) the optimization design software of the parameter for the worm gear was written by Visual Basic 6.0; 2) the parameter modelling software for the reducer was developed by using AutoCAD2000/VBA. This thesis reviewed the mesh theory of plane double-enveloping worm gearing: the equations including the first enveloping equation, the second enveloping equation, contact line equations of the first enveloping and the second enveloping, boundary equations of the first enveloping and the second enveloping, the equations of relative velocity and absolute velocity. The thesis developed the optimization design software of geometric parameter for the worm gear including strength check module, the drawing contact lines module, the change lines of tooth thickness of worm, and the parametric modelling software for the reducer which includes parametric modelling of parts and assembly. The CAD prototype system is very convenient because of its accessible interfere, simple operation and written in Chinese. By input design parameters,the CAD system can make optimization design and strength check for the worm gear,draw contact lines of tooth flank of worm-gear and change line of tooth thickness of worm,judge if the tooth flanks of worm undercut and if the sideward tooth of worm-gear hob come to a point,make project design and structure design for the reducer and draw its 2D parts and assembly. Finally the thesis gave an application example to verify the advantages of the CAD system.