Research On The High Speed And High Precision Control And Error Compensation Algorithms Of Electronic Gearbox

As the important fundamental parts of the machinery industry,the processing efficiency and accuracy requirements for gears are getting higher and higher.CNC gear processing is a significant means to achieve high speed high precision machining of gears.And it has a vital role to improve the gears machining quality and efficiency.High performance gear processing CNC system is the key to realize high speed and high precision gear processing.The Electronic GearBox(EGB)whose control accuracy decides the capacity of the CNC system and the gear machining accuracy directly is the core technology of high performance gear machining CNC system.Carrying out the research on high speed and high precision control and error compensation algorithm of EGB is of great theoretical and practical significance to improve the performance of gear machining CNC system and realize high precision and high precision NC gear machining.For the development of high performance worm wheel gear grinding CNC system,in this dissertation the basic principle of the worm wheel gear grinding and the machine tool structure of CNC worm wheel gear grinding machine are studied.On this basis,the movement process of the worm wheel gear grinding machine is analyzed and the linkage mathematical models of worm wheel gear grinding processing and worm wheel dressing are deduced.Through the EGB phase synchronization control technology,the automatic phase synchronization between worm wheel and gear and diamond wheel is achieved when the gear is grinded and the worm wheel is dressed.With above research work,the EGB of the worm wheel gear gringing processing and the worm wheel dressing are designed.And the EGB are realized and inserted in the self-developed gear machining CNC system by complete software mode.The control performance and the validity of the EGB control system software are verified through the software and control test.For the questions of EGB high speed and high accuracy tracking control,the model of servo feed drives are built firstly in this article.The feed drive parameters are identified based on the proposed unbiased least square method.And the composite tracking controller based on dynamic model feedforward,optimal cascaded PID/PI control and velocity/acceleration feedforward is proposed to achieve the single axis trajectory tracking control of EGB contrl system.In order to reach the aim of high precision synchronization control,the effects of multi-axis sync error on the gear machining error are analyzed and the EGB synchronous coupling control strategy is proposed.The test results show that it can effectively improve the multi-axis synchronous accuracy of EGB control system.In the field of multi-axis coordination control,the contour error is a more important evaluation index than the tracking error.In view of the generating machining contour control error,the mapping principle between the control error of EGB and gear machining error is studied,and the contour error model of gear generating machining is constructed.The experimental results show that the gear machining error causing by the EGB motion control error can be accurately estimated with the constructed gear tooth surface contour error model.For the sake of attaining high precision contour error control of multi-axis system,the EGB contour error precompensation control method is put forward based on the traditional contour error compensation control.According to the EGB control system feed drive models,the tracking errors of each machine tool axis are predicted and the gear tooth surface contour error also can be obtained based on the gear generating machining contour error model.With the preposed error precompensation module,the estimated contour error can be compensated in advance.Current non-circular gear manufacturing process all use discrete machining method,which breaks the instantaneous meshing relationship between the cutter and workpiece gear,generates a large number of small line segments without smooth kinematic characters,etc.To deal with these questions,the non-circle gear continuous generating machining method is proposed in this paper.The non-uniform transmission ratio EGB linkage control models aiming at completing non-circle gear absolute generating enveloping processing are designed combining the mathematical model of gear hobbing and gear shaping.They are embedded in the gear machining CNC system mentioned previously.The trajectory path characteristics of each gear cutting machine axis are analyzed through a processing instance.The results show that using the continuous generating machining method proposed above the reference trajectory has smooth kinematic profile feature during the whole machining process.It plays a key role in the computer control of machine tools.Meanwhile,the machine tool has a large tracking error fluctuation range when the velocity and acceleration of the reference tracjectory change real-time during the machining process.And it will lead to the inconsistent processing quality on different location of a same gear.To solve the problem,the non-uniform transmission ratio EGB repetitive learning control strategy is proposed to realize steady precision tracking the real-time varying velocity and acceleration reference tracjectory.The experimental results show that the non-circle gear machining precision can be improved effectively by the proposed continuous generating machining method.And the flow meter indication error can be reduced up to 90%or more.