Nozzle Deep Holes Adaptive Drilling System

To solve the problems of low efficiency and the breakage of the drill bit during the process of drilling a deep small hole in a fuel injection nozzle, a system of automatic adaptive drilling has been designed in this paper. An experimental system has been developed and tested. In this system, the drilling torque achieved in the real-time detection is taken as the control variable. The controlled variable, the feed speed of the drill, is calculated according to PID control algorithm, which is then dynamiclly realized by changing the speed of the stepping motor. Two methods have been used to collect a torque signal, one is the method of torque float measurement, and the other is the method of spindle motor current measurement. In the method of torque float measurement, the change of the drill's torque at work is transformed to that of the angle of a rotary potentiometer by means of a torque measurement device of rotation axis; In the method of spindle motor current measurement, the change of the spindle motor current is transformed to that of voltage by means of a hall magnetic current sensor to reflect the change of the working condition of the drill. Mechanical structure of the experimental system has been introduced, including the base of the machine, a stepping motor and the torque measurement device of the rotation axis; The function of each hardware circuit, main electronic components and their connections have also been introduced; The function, the structure and the flow chart of each subroutine have been introduced. The digital PID control algorithm is also introduced in this part; Proportional coefficient and integral coefficient of the PID control algorithm has been setting by means of the PID Control trial-and-error method experiments. Control experiments have been done on the experimental system. The results show that, the experimental system can effectively improve the drilling efficiency and prevent the breakage of drill bits.