Design And Implementation Of The Automatic Screw Machine Control System Based On PLC

Screw fastening,as one of the most common processes in industrial manufacturing,has led to increasing market demands for high-performance and efficient automatic screw machines.In this paper,a dual-channel automatic screw machine control system based on PLC is designed and developed.By combining PLC control technology,servo drive technology,and pneumatic technology,the system achieves automatic control of workpiece screw fastening and punching processes,improving the precision of screw fastening and punching while further enhancing processing speed and efficiency.The research content mainly includes the following aspects:(1)Taking the screw fastening requirements of a specific workpiece as a starting point,the process flow of fastening two small diameter ratio self-tapping screws on both sides and positioning punching is analyzed.The structural components required for each process action are designed: vibration screw feeding assembly,fixture movement mechanism,screw fastening mechanism,punching mechanism,and transfer mechanism.The overall technology plan for the automatic screw machine control system is designed: using a vibrating plate combined with a pneumatic pick-up method to supply screws,with two vibration screw feeding assemblies for supplying two types of screws;two fixture movement mechanisms carrying workpieces to be fastened to the fastening points and capable of flipping the workpieces;two screw fastening mechanisms carrying electric batches to complete the tasks of picking,feeding,and locking screws;a punching mechanism for carrying workpieces to the punching points;and two transfer mechanisms for loading and unloading punched workpieces.(2)The hardware configuration of the control system is designed and selected based on the technology plan of the automatic screw machine.The design incorporates torque detection control during the screw fastening process,sets up a flipping device to fasten screws on both sides of the workpiece at a fixed angle,and introduces a CAN bus to control the servo system’s movement target.The vibration screw feeding assembly,fixture movement mechanism,screw fastening mechanism,punching mechanism,transfer mechanism,PLC,and touch screen,and other hardware are designed and selected,and the control system circuit is designed.(3)By analyzing the control system’s technology plan and hardware structure,a software scheme for the automatic screw machine control system based on the CAN bus is studied.The servo PDO variable mapping is defined,and the process flowcharts and servo point diagrams of screw fastening,fixture movement,and punching are drawn by analyzing the process flows.PLC programs are designed using SoMachine software,and touch screen interface programs are designed using MCGS software.(4)The hardware and software of the automatic screw machine control system are debugged,including communication debugging,pneumatic circuit debugging,servo system operation debugging,and overall system operation debugging.This thesis aims to solve the problems of high labor costs and low efficiency of screw fastening and punching in a certain enterprise.Considering the enterprise’s demand for fastening two types of screws on both sides of the workpiece and addressing common issues such as slip lock and floating lock in the screw fastening process,an automatic control system for screw fastening and positioning punching is designed and tested.Field operation results show that the system has a fast processing speed,completing screw fastening and punching tasks for a single workpiece within an average of 12 seconds,with a yield rate of 94.5%,significantly improving processing efficiency and meeting enterprise requirements.