Research on the architecture of CNC system for the

  • Detail

Research on the architecture of gear machining CNC system

the motion relationship of traditional gear machining machine tools is complex. Taking gear hobbing machine (or worm wheel gear grinding machine) as an example, there are generative indexing chain, differential chain, feed transmission chain and so on in gear machine tools. Adjustment is complex and time-consuming. The position and distance of fast approaching, working forward and fast retreating can be completed only after careful debugging or trial cutting, and many accessories are required

in order to improve the gear processing accuracy and efficiency, after the 1980s, the gear processing machine tools at home and abroad began to be digitally transformed and produced. Especially in recent years, the rapid development of microelectronics technology and the emergence of high-precision, high-speed response AC servo system based on modern control theory have provided good conditions and opportunities for the development of gear machining CNC system. We divide the gear processing system into two categories: full function and non full function

differential change gear box

structure of non full function gear processing CNC system

the feed axis of machine tools equipped with this kind of CNC system is CNC axis, and the method of calculating the impact strength of film pendulum impact testing machine is mostly used to serve the system. Since the CNC of gear processing just started in the 1980s, when the CNC technology could not meet the requirements of high synchronization of gear plus machine tool extended component chain, the extended indexing chain and differential chain are still traditional mechanical transmission. This kind of numerical control processing method is much more convenient to adjust than mechanical gear processing machine tools. Through the linkage of several coordinate axes, they can realize the machining of tooth direction modified gears, omit the profiling and other devices required by the traditional machining of modified gears, and improve the productivity and machining accuracy. However, this kind of gear processing CNC system is an economic CNC system. Because its expansion component degree chain and differential chain are still traditional mechanical, the gear processing accuracy depends on the accuracy of the mechanical transmission chain. At present, this kind of gear processing CNC system is mostly used for the NC transformation of the existing mechanical gear processing machine tools

In recent years, due to the rapid development of computer technology and the emergence of high-precision, high-speed response servo system, full-function CNC gear processing machine tools have become the mainstream products in the international market. Full function numerical control means that not only the feed motion of each axis of the gear machine tool is numerical control, but also the generative motion and differential motion of the machine tool are numerical control. At present, the numerical control processing methods of generative indexing chain and differential chain are different, including two types based on software interpolation and hardware control

indexing change gear box

gear processing numerical control system based on software differential compensation

the tool spindle of this kind of numerical control system is generally controlled by frequency converter, and the workpiece spindle is directly driven by servo motor through numerical control command. At present, most of the CNC systems configured by domestic CNC gear processing machines are general CNC systems of foreign well-known brands, so they all adopt this NC processing method based on software interpolation

the advantage of software based interpolation method is that the rotation speed of the workpiece spindle is completely controlled by the software of the numerical control system. Therefore, by compiling appropriate software, we can use general tools to process non-circular gears and modified gears with high precision and speed, and the machining accuracy is much higher than the traditional mechanical profiling method

at present, due to control accuracy, dynamic response and other reasons, the gear processing CNC system based on software interpolation is not competent for the requirements of high-speed and high-precision gear grinding machine. With the continuous improvement of computer speed, the emergence of new control methods and the improvement of control accuracy, this method is more and more widely used. In the generative indexing chain of traditional gear machine tools, the cutter and workpiece are dragged by the same motor. The transmission chain is very long, and it is often necessary to use transmission elements (such as bevel gears, universal couplings, etc.) whose accuracy is not easy to improve, so improving the accuracy of machine tools is limited

at present, the photoelectric disk pulse frequency division and indexing transmission chain is mostly used. The spindle of the grinding wheel rotates at a fixed speed and drives the sending element (such as the photoelectric disk). After the signal of the photoelectric disk is digitally divided, the servo motor of the workpiece shaft is controlled to rotate at a certain speed to achieve accurate indexing transmission relationship. At the same time, the differential chain of the machine tool is also included in the control system

advantages of gear machining CNC system based on hardware control: when hardware control is adopted, especially when phase-locked servo control with high synchronous accuracy is adopted, the accuracy is high and the response speed is fast. Disadvantages: the mechanism is relatively complex, and there is a hardware control circuit part more than the software interpolation method. At present, the electronic gear ratio (differential coefficient, main transmission ratio) controlled by hardware cannot be modified in real time, that is, the rotation speed of the workpiece spindle cannot be changed in real time, so it cannot be used to process non-circular gears, etc

because the machining accuracy of the non full function CNC system depends on the mechanical transmission chain, there is still the exchange of change gears, and the operation is more complicated, which has been less used. The future growth trend of smart energy is worth looking forward to. At present, it is mostly used in the numerical control transformation of existing mechanical gear processing machine tools; The CNC system of gear machining based on software interpolation has the advantage of great flexibility. It can easily process non-circular gears and various modified gears through program control, so it is widely used in hobbing machines and gear shapers with low machining accuracy; The gear processing CNC system based on hardware control, because the generative motion is directly adopted, 3 is to implement the green certification hardware control of express packaging products, especially when the phase-locked servo technology with high tracking accuracy is adopted, it can well ensure the differential and generative motion accuracy of gear machine tools, with fast response speed, but poor flexibility, which is suitable for gear grinding machines with high machining accuracy requirements

the full-function gear processing CNC system has become the mainstream product in the world, and it is bound to become the mainstream product in China. (end)

Copyright © 2011 JIN SHI