Research On CNC System For High Feedrate Punching Process And Two-Dimensional Optimum Layout

Being an important category of metal machining, metal sheet punching has its finished parts widely applied in many industries. Considering the ordinary problems in the field of punching process in China, such as low productivity, less CNC punching machine, low level automation and low benefit of the enterprises, this dissertation aims at developing a low-cost and practical high feedrate CNC system for punching process. The CNC system for high feedrate punching process is implemented. And two-dimensional optimal layout of blanking sample on rectangular sheet is also studied.Based on the analysis and referring to CNC system for punching machine at home and abroad, according to characteristics of punching process the mechanical structure of the automatic punching machine are designed. The structure of CNC system based on multi-CPU of single chip microcomputer and CRT display are developed. The multiple task parallel processing of CNC system is realized , and the high feedrate of punching machining is ensured in hardware.As concerning optimum layout of blanking sample, the optimum model establishment is generally based on progressive die technology, which is optimum layout of blanking sample on infinite or finite ribbon. However optimum layout of blanking sample on rectangular sheet is few studied, and the optimum algorithms existed has some problems. In the dissertation, the theory of two-dimensional optimum layout of blanking sample on rectangular sheet is thoroughly studied. Two mathematical models are set up and two optimum algorithms are proposed, which are two-dimensional optimum layout of blanking sample based on one parameter and two parameters respectively. And the optimum software is developed.Increasing/decreasing frequency curve of a stepping motor is one of the key technologies of stepping servo drive unit. According to torque-frequency performance of a stepping motor, the optimum increasing/decreasing frequency curve that is found by the experimental date is proposed. A series of dispersed frequencies and the numbers of running step at every frequency are obtained by experiments, which solves the matching problems of speed-up and speed-down curve with stepping motor, drive circuit and load, brings the torque-frequency performance of a stepping motor into full play.The drive circuit of a stepping motor is another key technology. According to the requirements of high speed punching machining, a new drive manner for a stepping motor, which is run under high voltage constant phase current chopping wave and low voltage locking is put forward and designed.Based on the analysis of the positioning error of punching process, a mathematical model and algorithms of positioning error software compensation is advanced. The modelis suitable to point to point CNC positioning error compensation.The research on the anti-disturbance problem of the CNC punching process is made, and some suitable solving measures under workshop conditions are presented.The CNC system for punching process was mounted and tested in the workshop. It has been used in practical process, and got a good result.