PLC-based Automatic Coating Control System Design

The purpose of this article is to develop an automatic painting system that can be used to meet the needs of small and medium-sized enterprises for efficient and accurate automatic painting equipment.The original semi-automatic coating system was improved and optimized by using the TIA Protherm platform to build an industrial control network and add PID control for the level control of the paint storage and transportation part;at the same time,the closed-loop control of the analog control volume by PLC was studied to make the automatic coating discharge link more stable and improve the coating effect;in addition,the coating link was improved by using a single-axis servo system and turntable motor to process the three-dimensional surface of the workpiece to improve the coating efficiency.In combination with the field equipment,Siemens S7-300 series CPU314C-2 PN/DP master station is used for PID adjustment,HMI information collection,calculation and data transmission,and control the start and stop of the slave station.Compared with the old STEP7 300/400 programming software,the TIA application software is more convenient and faster in terms of integration,operability and hardware configuration,and can be debugged through WINCC HMI and 300 simulation module.At the same time,two 200 SMARTs with different functions are used as slaves for on-site control.Among them,S7-200 SR40 SMART is used for the control of indicator lights,valves and some motors,mainly responsible for the operation of paint mixing and part of the paint storage and conveying program;S7-200 ST30 SMART is used for the control of single-axis servo motor,stepper motor control and analog signal control of inverter,mainly for the operation of automatic painting and paint storage and conveying inverter part of the program.The automatic coating system combined with WINCC human-machine interface,after repeated verification and on-site testing,has realized the complete production process of the automatic coating system,providing ideas and solutions for practical engineering applications.It also solves the problem of the stability of horizontal spraying with the rotary motor,which solves the difficulties in the production process and improves the stability and efficiency of the system.