| Recently years, with the rapid development of manufacturing industry such as shipbuilding and automobile manufacture, the demands of metal cutting have increased largely. Consumers also have an urgent requirement for higher productivity, improving product quality, solving the problem of labor shortage, reducing quantity of secondary process and improving the working environment. So, the market of automatic NC (numerical control) cutting machine is expanding. Though there are a lot of consumers who have a strong desire of using NC cutting machine, the price of large NC cutting machine makes them hesitate. Portable NC cutting machine is popular with the medium-sized consumers for its low price (1/5~1/10 of the large NC cutting machine price) and integrated functions. Its sales are growing rapidly ever since its appearance. Obviously, it has a bright market prospect and a large developing potential.Commissioned by a cutting machine manufacturer, the essay aims at the design and development of the control system in portable cutting machine. Firstly, the scheme of the whole system is put forward based on the survey of the domestic NC cutting machine industry. DSP and MCU are used as the core components of the system. The main job and characteristic which author has accomplished is summarized as follow.(1) Implemented the hardware design of the system including power module, DSP external interface circuit, step motor control and drive module, LCD control module, USB interface module, input and output module, keyboard module and so on. Through USB interface, system can load the codes in flash disk which is generated by external software. So, there is no need for consumers to do programming themselves. Though the precision of step motor is not as good as that of servo motor but, it is cheaper and qualified for flame cutting whose kerfs is about 4mm. As the control chip of motion, DSP has made full use of its event control module (supports motor steering, generates advanced PWM signals, exchanges data, monitors system, etc.) and meets the requirement of incisal speed and incisal quality as well. Using 320*240 dots LCD to display the real time data is no worse than the large numerical control system.(2) Developed an assistant code generation software which runs on PC and provides a lot of functions including Shape Library, code conversion, text editor, part nester, part repeat, kerfs compensation and so on. The software takes advantage of PC resources to make up the shortage of the portable cutting machine hardware resource. So, it solves the contradiction between cost and performance.(3) Finished the software design of the system which is the brain of the entire system. Software design includes interpolation algorithm of line and arc, motion control (backup and forward on path, I/O logical, etc.) rush job interrupt, USB communication, system monitor and so on. All these functions make the system intelligentized and stable without cost increase.(4) Made the system prototype and used the cutting machine to do the debugging and test after the completion of hardware and software design. After three generations'improving, the system turns out to be running smoothly and performing well. Its highest speed is up to 12000mm/per minute and its precision error is less than 0.5mm.Test results show that the functions and technical indicators of the system have reached customers'requirements. After further testing and reliability assessment, the system is expected to have trial-production. |
PDF Full Text Request