Research On The Error Modeling And Control Of The Worm Gear Grinding Machine

Gear as an important basis part in industrial production, because of its complex shape, technical issues and machining difficulty, has been deeply valued in the industry. With development of science and technology and the improvement of the equipment level, the requirement of transmission gears is increasingly higher. Due to the high production efficiency, it has also raised new demands for the3-6class worm grinding wheel which is suitable to the mass production of medium and small module gears. Now, the CNC system of gear cutting machine is mostly foreign, such as Germany’s SIEMENS, FANUC of Japan and NUM of France or the secondary development based on the general CNC system. But the secondary development, which embeds the gear machining technologies into CNC system, is lack of specificity and not strong in scalability. To improve the gear precision and performance, it is quite essential to develop specialized gear CNC system and then the gear grinding will no longer rely on the foreign CNC system. Therefore, this paper is studied on how to develop an embedded CNC system for worm wheel gear grinding machining and design the software and hardware to further improve the precision of CNC system. The main researches can be summarized as follows:1. Based on the analysis and research on the machining and the movement principle of worm wheel gear grinding and the calculation of grinding trajectory, travel range and the coordinates of the key points of grinding tool, the machining mathematical model of the worm wheel gear grinding has been derived. The machining and the dressing NC code models have been generated by automatic programming system.2. Depend on the requirement of high speed and precision of the CNC system of gear machine tool, a platform of hardware and software embedded with the technology of warm wheel gear grinding has been designed. An embedded CNC system of worm wheel gear grinding has been developed which has the design of human-computer interface, different function modules, interpolation module, the interface of the parameterized automatic programming, grinding technic database, compensation system of geometric error and thermal error. And the embedded CNC system has been experimentally studied on the self-development CNC system platform.3. The topology of CNC worm wheel gear grinding machine has been described on the multi-body system theory and the error has been estimated with the homogeneous transformation matrix on the machine tool error on kinematic principle. The geometry error of worm wheel gear machine has been obtained through the research of kinematic error between the prismatic and revolute pairs on the CNC worm wheel gear grinding machine. Based on the hypothesis of small error dynamitic compensation and the principle of differential transformation, decoupling errors of every axis which have effects on the accuracy of gear grinding is to get the mathematical model for decoupling geometric error.4. Using the grinding basic theory to provide a3D thermal modeling for inverse calculation of heat transfer by the plane grinding experiment and the simulation in theory. The3D thermal model of plane grinding is built with the experiment and the simulation on the finite element software by the temperature and grinding force measured in the machining process. And the temperature value of the grinding contact zone can be obtained based on the result of simulation. The grinding3D thermal model has been built by inversely calculating temperature on the workpiece surface through the measured temperature at the different areas under the grinding contact zone. The result of energy proportion shows that this method is feasible and it is a new method for grinding thermal modeling.5. By the definition of energy proportion, provide a method for researching the dynamic energy proportion by grinding with two workpieces. With the analysis and calculation of the contact length of gear grinding and the value of temperature and force measured several times in the worm wheel grinding process by the two workpiece grinding method, the energy proportion variation can be calculated by the inverse calculation of heat transfer method. And the research result has been used on the thermal modeling of worm wheel gear grinding and an in-depth study has been done about the thermal mechanical coupling. The research result is great helpful to get reasonable machining parameters reduce the tooth surface burn and improve the grinding accuracy of tooth surface.