Design Of The Focus Control System For Mental Laser Cutting Machines

After 50 years of development,laser cutting technology has become an important part of advanced manufacturing technology,the characteristics of high-precision,high efficiency,small pollution and so on make it has been widely used in metal cutting fields.Focus control system is a vital part of a metal laser cutting machine.It is directly related to the consistency and accuracy of the distance between the laser focus and the workpiece,which determines the cutting quality of the metal workpiece.So the design of a focus control system for laser cutting of metal has very important significance.Therefore this thesis designs focus control system for laser cutting machine of metal with the DSP as the controlling core.At first,the paper introduces the research background and significance,then analyzes the research status and the development trend for the domestic and international focus control system.It analyzes the requirement of the metal laser cutting machine focus control system,and complete the overall framework of the system design.By comparing the advantages and disadvantages of the various position detecting means,according to the characteristics of the metal laser cutting systems,select capacitive displacement sensor as a sensor to detect the distance between the laser focus and the workpiece.Combined with the traditional PID control theory and fuzzy control theory,it achieves the closed-loop control for the laser focus position,and designs fuzzy PID controller for the focus control systems of the metal laser cutting machine.Through the analysis of the mechanical structure and electrical characteristic of the laser cutting capacitance sensor,the mathematical relationship between the laser focus and the workpiece is derived.It adopts theoretical calculation of the changes in capacitance to provide theoretical support for the design of the capacitor capacitance detection circuit and the capacitor signal processing.The paper designs the capacitance detection circuit with Pcap01 as the core chip,and sends capacitance signals to the focus position control module by SPI communication.The paper complete the hardware and software design of the laser focus control system with DSP as the core chip.Collocating with hardware circuit,the software module of system achieves the function of laser focus control system.Among them,the program of the least squares curve algorithms is designed for non-linear correction capacitor data to obtain linear measurements of the focus position;Combined with the traditional PID control algorithm and fuzzy control algorithm,it designs a fuzzy PID controllers focusing on this particular applications of laser cutting.The paper also simulates for the controller,and achieves the implementation with software method.Finally,a test platform is set up to test the performance of metal laser cutting machine focus control system.By comparison,the experimental results can match the performance requirements.