Application of single chip microcomputer control system in EDM machine tool

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Application of single chip microcomputer control system in EDM machine tool [Copy link]

1 Introduction
At present, in the oil pump nozzle industry, most of the traditional nozzle processing relies on manual operation determined by personal skills, with unstable product quality, low production efficiency, high labor intensity and high scrap rate.
This system is designed for an EDM machine tool, which adopts the negative discharge method, that is, the discharge of brass to the workpiece to achieve the processing purpose. Through the test, the consumption ratio of brass to the workpiece is obtained, and the required processing depth is controlled by the program. The processed nozzle seat surface fully meets the requirements, improves the processing speed, ensures the processing accuracy, and completely replaces the traditional wind grinding processing. 2 Design idea According to the nozzle processing technology and the parameters of the processed workpiece, the electrode is driven by the stepper motor to move. It is necessary to accurately and automatically sample in real time, change the working frequency of the stepper motor to control the feed amount of the stepper motor. In order to meet the requirements of the nozzle seat surface, during the processing process, according to the consumption ratio obtained by the test, the table lookup programming method is used to correct the electrode in real time, which is completed by controlling the grinding wheel motor. According to the processing depth of different rough workpieces, the corresponding frequency and the number of steps of control operation are adopted. The process sequence control logic includes: (1) Rapid approach: In order to improve work efficiency, after the workpiece is installed, the stepper motor must quickly approach the surface of the workpiece being processed. (2) Rapid retraction: After the preset processing volume is processed, the stepper motor must retract to the initial position. (3) Rough grinding: For large-sized blanks, in order to improve work efficiency, you can choose to perform rough processing separately. During rough processing, the stepper motor feeds at the rough grinding speed. At the same time, by changing the discharge voltage and switching the discharge capacitor, the discharge spark is controlled, and the discharge is fast to increase the processing speed. (4) Fine grinding: When the processing size is small, in order to ensure the angle and smoothness of the seat surface, fine grinding is used. During fine grinding, the discharge spark is small and the processing voltage is low. This is also achieved by controlling the software to switch the processing voltage and discharge capacitor. (5) Rough and fine grinding: This system can complete rough and fine grinding in one go. Rough grinding is used at the beginning of processing. When the processing is within a certain range ( such as 3 threads ) , the system automatically switches to processing. This not only improves the processing speed, but also ensures accuracy and smoothness. The system can control the amount of spark discharge in two processing modes. We choose a three-phase stepper motor (45BF3) as the electrode feed drive component. The controlled stepper motor has three basic working modes: forward rotation ( feed ) , reverse rotation ( retract ), and stop. Forward and reverse rotation have different operating frequency requirements ( i.e., feed or retract speed ) . The feed and retract speeds are adjusted according to the software. When the three-phase winding of the stepper motor is energized in the order of A → AB → B → BC → C → CA → A , forward rotation can be achieved. Conversely, if it is energized in _the order of A → AC → C → BC → B → AB → A , reverse rotation can be achieved. If the output state remains unchanged, _the motor stops running. The three-phase winding of the motor is controlled by _{P1.0 , P1.1 ,} and P1.2 of the _P1 port of 8031 to control its operating _{mode .} During the processing, the processing voltage and discharge capacitor should be controlled at the same time. When the processing electrode is repaired, the voltage of the workpiece and the motor should be switched. These are all realized by software to control the opening and closing of each relay in a certain sequence. 3 System Hardware Design The hardware of this system consists of four parts, namely the basic system composed of 8031 single -chip microcomputer, 2764EPROM and 74LS373 , the drive circuit, the sampling circuit and the display and keyboard scanning circuit. Here we mainly introduce the basic system and the drive circuit. 3.1 Basic System The system has a 5- digit display and 7 buttons. The display displays the processing mode status, setting value and processing remaining amount respectively. The seven buttons are: start, reset, pause, ten position digit, unit position digit, set number function key, processing mode selection. When the set number button works, the tens position and the unit position can be set. The processing mode selection can choose coarse grinding and coarse fine grinding processing methods. In the software, the processing amount of 1 to 99 wires is converted into corresponding data according to a certain conversion relationship and stored in a table. During processing, the data in the corresponding table can be taken according to different processing amounts. The LED display and keyboard are connected by serial input and parallel output shift register 74LS164 . The system schematic diagram is shown in Figure 1 .

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wein1314121

It's quite detailed. It's a good thing.

guang2009