Research On Motion Analysis And Control System Of Spiral Bevel Gear NC Milling Machine

IIIBecause of the excellent dynamic performances, spiral bevel gears play a very important role in machinery industry, and are primarily applied to aviation, marine, automobile, precision machine tools and other projects. The processing design of spiral bevel gears is comparatively complicated, and meanwhile, the owners of the technology, such as Gleason corporation, are engaged in a technological monopolization Therefore, many countries are prompted to the technology research and exploration, and the spiral bevel gear drive in the design, manufacture and testing technology has been very active in the field of gear manufacturing. While domestic enterprises have developed several different series of spiral bevel gear NC Machines, the control kernel is the foreign NC systems, such as SIEMENS, FANUC and so on. It makes that the domestic spiral bevel gear design, manufacturing and other areas is still subject to few number of foreign monopolies, seriously hindering our manufacturing development.Supported by natural science foundation of Jiangsu province (BK2003005) and the tackle key problem of science and technology office of Jiangsu province (BE2003031), this dissertation is to study the theory of NC machining spiral bevel gear, to design the open-architecture NC system based on the motion controller independently, and to develop the control system of spiral bevel gear NC milling machine with self-owned intellectual property rights.Firstly, the processing principles of spiral bevel gear, the modification method of tooth surface, and the adjustment of machine-tool settings are investigated. Based on the movement relationship between the cutter head and the work gear in the process of spiral bevel gear machining, the NC generation of gear cutting is realized by means of the vector transformation. The coordinated motion of NC coordinate axes is expressed as quintic parametric spline functions, which use the rotation angle of the work gear as the parameter. Then the computation time is greatly reduced, the interpolation algorithm is easy to implement, and the NC generation can be precisely implemented.To obtain the tooth surface contact point, the implement of quasi-Newton method may make the calculation process easily divergent, and the variable interval constraints are not considered. In this dissertation, it is proposed that the solution of the contact point is conversed to constrained optimization for minimum and the complex method is used to solve this problem. The complex method search speed is slow, especially when the number of variables is large. Therefore, based on the condition of normal coincidence at the contact point of mating gears, the constrained optimization problem is simplified to contain only three design variables. The tooth contact of the spiral bevel gear processed by NC method is analyzed. The method of amendment of gear-cutting calculation in the NC system is proposed to improve the contact condition of the tooth surface.Secondly, an adaptive acceleration-deceleration control method of parametric curve interpolator is presented. In the interpolation preprocessing, the velocity profile is analyzed, where the feedrates are varied due to the contour errors. The accelerations and decelerations are controlled with the consideration of the limited jerk. With the proposed approach, the machining accuracy is guaranteed. The feedrate is adaptively adjusted and smoothed according to the curve shape. The shock imposed on the mechanical parts by the variation of accelerations and jerks is efficiently avoided. Based on such adaptive acceleration-deceleration control method combined with spiral bevel gear NC machining, the high-precision parametric interpolation algorithm of spiral bevel gear NC machining is proposed. The algorithm is applied to the self-developed spiral bevel gear NC milling machine to control the gear cutting.A 6-axis open-architecture NC System with 4-axis simultaneous control based on the motion controller is developed independently. The NC system is based on the PC bus, and the motion controller uses the 486 microprocessor and programmable logic devices (CPLD, FPGA) as the key components. According to the above spiral bevel gear NC machining theory, a control system of spiral bevel gear NC milling machine is developed with self-owned intellectual property rights. Exampls of actual cutting are presented to demonstrate the validity and effectiveness of the proposed spiral bevel gear NC machining theory.High-precision processing of spiral bevel gears with the implement of self-developed spiral bevel gear NC milling machine can break the foreign monopolization of spiral bevel gear NC machining technology, and make contribution to improve our manufacturing level of gears and machine tools.