Zhejiang Business Vocational College (No. 1988 Airport Road, Ningbo, Zhejiang Province, 315012, China)
*This project was funded by the Zhejiang Business Vocational College Student Science and Technology Innovation Project.
Abstract This paper presents a simple project design for a CNC single-axis feed device to achieve the movement of an object on the X-axis with very high positioning accuracy.
Keywords: servo control; touch screen; GE PAC
1. Project Background
In actual industrial automation production processes, a large number of equipment involving material processing can be seen everywhere. Early equipment mainly relied on manual or simple mechanical positioning, such as using the effective stroke of a cylinder to achieve positioning. Its characteristics are simple principle, low equipment cost and maintenance cost, but its biggest drawback is low precision and poor consistency.
With the increasing creativity in product and component design, traditional manual or mechanical control methods are no longer sufficient to achieve precise position and speed control across multiple surfaces simultaneously, nor can they improve production efficiency and product quality. The emergence of servo control systems has solved this problem for the manufacturing industry. However, using single-board computers or microcontrollers requires not only software development but also the design of hardware circuits, interface circuits, and drive circuits. The advent of programmable logic controllers (PLCs) has solved this problem. Therefore, this project is a control system design based on GE PAC SYSTEMS, using the X-axis position status as the controlled object, a GE PAC as the controller, and a Quick Panel touchscreen for control. The movement of objects on the X-axis is controlled by GE's program, achieving precise positioning.
Once completed, this project can be applied to the drilling machine shown in Figure 1 to realize various positioning control functions of the drilling machine, and can be set and displayed directly on the touch screen.
2 GE Servo Control Hardware Design
The servo control system uses PLC programming to achieve the positioning and control of an object, including an electrical control loop and fiber optic control signal lines. The electrical control loop mainly consists of relays and a servo motor mounted on the X-axis to realize its electrical circuit control.
The servo control system hardware module is shown in Figure 2, which can be specifically divided into the electric part, the panel part, and the transmission part:
(1) Electric part
A. AC chopper B. Transformer C. Servo controller D. Intermediate relay F. AC contactor
(2) Panel section
A. Orange emergency stop button B. Red stop button C. Green start button
(3) Transmission section
A. Servo motor B. X-axis
3. Setting up and programming the DSM324I servo control module
In this project, the DSM324i module from GE PAC was mainly used, and its settings are shown in Figure 3.
X-axis settings
The main program of the servo control system is shown in Figure 4.
Figure 4 Main Program
Figure 5 shows the jog control interface for the x-axis. Through this interface, users can precisely control the feed and retraction distances of the tool feed device, thereby achieving precision in product processing.
Figure 6 shows the x-axis position control interface. Through this interface, users can set the feed distance, making product processing more flexible and easier to operate.
4. Conclusion
In servo control debugging, the first and most important step is to carefully check the external wiring between the PLC and the servo controller. The external wiring must be accurate. Alternatively, a pre-written test program can be used to scan and power on the external wiring to locate wiring faults. The simulated and debugged program is then loaded into the user memory for further debugging until all parts function normally and can coordinately and consistently perform the control function of the single-axis feed device.
