Research And Development Of Electrostatic Powder Coating Control System For Aluminum Profile

Since the 21st century,China has become a major manufacturing and consuming country of aluminum products,of which more than 60%are the aluminum profiles.The coating of aluminum profile usually adopts the way of electrostatic powder coating,because of the high degree of automation coating control system,large enterprises have high production efficiency and good product quality;small and medium-sized enterprises have more general product quality due to the limitation of cost and the control system is not intelligent enough.With the people's pursuit of a better life,the aluminum profile of good quality could not meet the national demand.Small and medium-sized enterprises need an electrostatic powder coating control system with cost-effective,high degree of automation and good coating quality stability,so as to enhance product quality and improve production efficiency.In this paper,according to the actual needs of the enterprises,the electrostatic powder coating control system for aluminum profile is researched and developed.The lower computer system realizes logic control and the collection of sensor information.Parameter adjustment,data transmission and other functions are completed by upper computer software.Based on the experimental research,the multivariable distribution model of the coating thickness of aluminum profiles is established and integrated on the software.Automatic coating control and adjustment guidance of coating parameters on the production line are realized.Finally,the application and operation of the control system are carried out in the enterprise.The main research work is as follows:First,based on the workflow and control requirements of the production line,the control schemes of the control system,lower computer system and upper computer software are formulated.The system control process is determined.And the platform hardware is set up,which includes industrial computer,gun controller and gun,CAN module,PLC and light curtain sensors.Combined with the hardware of the lower computer system,I/O points of PLC are allocated and based on the Step7 software,the main program and subroutine of PLC are designed.Compared the communication protocols supported by the PLC Ethernet port,the high-speed and stable S7 protocol is selected.The S7 protocol messages and the data frame structure of the CAN module are studied.Secondly,in view of the long debugging process of electrostatic powder coating parameters and the lack of theoretical guidance for parameter adjustment,the influencing factors of electrostatic powder coating are analyzed.And the experimental variables are determined as electrostatic voltage,powder flow rate and coating speed.The coating experiments are carried out by control variable method.Based on the Gaussian distribution,the fixed-point experimental data are fitted and optimized by varying the Gaussian peak width.The effects of electrostatic voltage,powder flow rate,coating speed and gun spacing on the film thickness distribution are analyzed by the experimental data.A multivariable variable Gaussian distribution model of electrostatic powder coating is established.Besides,based on QT 5.12,the upper computer software is designed in hierarchical architecture mode,and developed by the optimized FLUX mode.Data and messages are transmitted separately through event router mechanism,which improves the running efficiency of the software.A clear,intuitive and interactive view interface is designed,a UML class object model of the software is established,and the core services such as system controller,file accessor,data communication service,state cache and film thickness simulation module are designed and implemented with emphasis.Finally,the application and operation of the control system are carried out in an aluminum profile manufacturing enterprise in Zhaoqing city,Guangdong Province.The operation results show that the variable Gaussian distribution model is accurate and effective,and the electrostatic powder coating control system for aluminum profile can realize automatic coating,which meets the production requirements of enterprises.At present,the control system has been worked in more than ten domestic aluminum profile production enterprises,and could keep running for a long time,improving the quality of aluminum profile products and the production efficiency of the enterprises.