Study Of On-line Monitoring And Control Technology Of Micro-hole Drilling

Micro-holes are welled used in accuracy-machine, electronic device and optics system. Among all methods that applied to produce micro-hole, drilling is most fashion method for the high-quality and efficiency. However, it is difficult to estimate that when the tool is going to break. In the process of drilling, current of the motor of principal axis has direct relation with the tool condition. But the current signal is very weak, changes frequent and with many noise signal. So it is necessary to build up a system based on DSP that acquire and process the signal in real-time, and could feedback to control the motor.In this paper, an experiment platform is built up which is based on DSP. Hardware includes micro-hole drilling machine tool, HALL current sensor, DSP, power magnifier and so on. Software includes data acquisition model, data processing model, subsystem of step-motor and so on. With the TMS320F2812 DSP chip of TI as the core of the system, the chip integrated many advanced peripherals, and offer a good develop platform for motor control and other movement control field.During the process of drilling, the current signal of the primary axis is switched to the voltage signal through the HALL current sensor and is sent to DSP. Then DSP disposes the collected signal, makes judgment of the drilling estate through the change of the current of the primary axis , decides whether keep on drilling or fall back to end drilling. Because the signal sent out from DSP is very feebleness, it is necessary to magnify the pulse signal through power magnifier in order to improve the drive ability of step motor.With the Integration Develop Environment in MATLAB platform, a program is designed in the manner of figure with C28x DSPlib, Simulink and other Arithmetic libraries, and simulated in the Simulink environment. The program is generated executable files with Real-Time Workshop automatic, and loaded to the target DSP to run. Finally, we connect hardware and run the software and debug it.Check various function of the system and execution time of the program.It is verified that the monitoring system based on DSP could predict the tool wear, and quit tool timely and avoid tool break effectively. Provide an effective method for on-line monitoring tool state in micro-hole drilling. The system replaces the former one with DSP chip. This monitoring method greatly increases the process speed, and accordingly improves the real-time ability.