The Design Of Numerical Control System For Piston Soft Template Technology Based On DSP

Soft template technique is widely used in digital control machine tool system for middle-convex and varying ellipse piston machining, due to its high machining efficiency, high ellipticity, high flexibility and so on. The application of soft template technique makes higher performance demands on turning tool feed rates system of machine tool. For instance, high frequency response, precision, rigidity and well controllable must be satisfied.The operating current range of turning tool feed rates system is5A DC-50A DC and operating voltage is550V DC. It has the advantage of simple mechanism configuration, low cost, well controllable, convenient for maintenance and high control precision, because the turning tool feed position is adjusted according to load current variation. The current of turning tool feed rates system is controlled by IGBT on and off under PWM method, as a result, the turning tool move forward and backward by μm along the X axis.This design uses TMS320F2812as the arithmetic and control unit, EPM1270T144C5as the assistant processing and monitoring unit, sufficiently uses the advantage of DSP and CPLD to improve the system response and control precision, and reduce the design of the circuit. DSP compute the output according to the turning tool position feedback and control the soft template machining. In the machining process, the processing unit determines the turning tool relative position of vertical axis (Z axis) and section axis (X axis) of machined piston profile, according to the signal of Z axis and X axis coder, reads the soft template curve data simultaneously and then make a new output data by comparing this curve data with the data of the position sensor and PI operation, controls the turning tool position, realizes piston machining in terms of output curve tracing soft template curve.The aim of this dissertation is searching a new approach of soft template numerical controlled machine tools, using a new turning tool feed rates system controlled by current strain micro-displacement of Giant Magnetostrictive. It provides high machining precision as well as low cost.