The Process Control System For The Preparation Of Diamond-Like Carbon Films On The Inner Wall Of Tubes

Metal tubes are generally used in relatively harsh environments,and the inner wall of tube is easy to suffer corrosion and damage.Diamond-like carbon films have become one of the new protective materials for metal pipes because of excellent performance.The preparation system of the diamond-like thin film on the inner wall of a metal tube is mainly controlled by instruments,and the process parameters fluctuate intensely during the preparation process.Hence,the stability and accuracy of control system are relatively low and the performance of the prepared films is not excellent,which cannot meet the intelligent production process.In this paper,a process control system for the preparation of diamond-like carbon films on the inner wall of a tube is taken as the research topic.The comprehensive control system scheme for the preparation process of diamond-like carbon film on the inner wall of the tube was designed,and the key parameters involved in the process control system are introduced and the problems of existing instruments are analyzed.According to the characteristics of different parameters,different control algorithms were selected to control parameters and each control algorithm was designed and simulated by the Simulink tool of Matlab software,and the simulation results were analyzed and concluded.Finally,the experiments were conducted using existing equipment to study the effects of power frequency and pulse width on film performance.The research content includes the following parts.After understanding the production process flow and process requirements for the preparation of diamond-like carbon films on the inner wall of the tube,we designed a comprehensive control system scheme for the preparation process of the diamond-like film on the inner wall of the tube.The instrument control and PID control were introduced and some problems of existing instrument control were analyzed,and the characteristics of PID control and its control principles were exhibited in detail.Appropriate control algorithms were selected to control parameters,according to the different characteristics of some parameters.The double closed loop ratio control algorithm is used to control the gas flow,and the double closed loop control system is designed and simulated.The simulation results show that the control accuracy is improved and the ratio of the gas flow of acetylene to silane can be kept constant.The feedforward control algorithm is used to control the pressure,and the feedforward control system is designed and simulated,and the simulation results showed that the control effect is well and the anti-disturbance performance is excellent.The cascade control algorithm is used to control the frequency and pulse width of power supply,and the cascade control system was designed and simulated,and the simulation results showed that the system overshoot and time increased as the frequency and pulse width increased.In addition,with the help of existing platforms and equipment,the effects of the frequency and pulse width on the performance of the film on the inner wall of the tube were studied.As a result,it was found that the uniformity of the film was the best under the conditions of low power frequency and low power pulse width.Therefore,the experimental results indirectly indicate that the simulation results are valid.The purpose of this paper is to make the process control system for the preparation of diamond-like carbon thin film on the inner wall of the tube can approach the automatic control system,and reduce the errors or operation errors as much as possible,and improve the control accuracy.In this paper,the simulation results and experimental results provide a certain theoretical basis for the application of actual control systems,and the design of the integrated control system also provides a guide for the construction of the control system.The diamondlike carbon film preparation process control system on the inner wall of the tube can realize the intelligence of the production process and save the greatest possible people and material resources.