Research On Key Technologies Of Plasma Cutting System Based On MFC For Thick Plate

In the fields of marine engineering,nuclear power engineering,petroleum and chemical industry,the main structure of the devices tend to be larger and more complicated which lead to the constantly increasing requirements on the thermal-cutting technology.At present,there are a lot of problems in the process of plasma cutting for thick plate such as the poor cutting quality,the low efficiency of cutting power supply and the low degree of automation in the plasma cutting process,that seriously influence the popularization and application of thick plate plasma cutting equipment.To solve the problem stated above,a plasma cutting system based on MFC for thick plate is designed in the dissertation.The system is composed of MFC control panel,plasma cutting control cabinet,two digital plasma cutting power suppliess,robot control system,thick plate plasma cutting torch,gas circuit system and cooling system.In the system,the MFC control panel can realized human-machine interaction.With the CAN,the cooperative control and parallel current sharing between the digital power supplies is realized,which can improve the output power so as to promote cutting efficiency and improve cutting quality.Firstly,the research status of plasma cutting is described,the key to improve the cutting performance for thick plates that is to improve the power density and stability of plasma cutting arc is pointed out.With the combination of a series of technologies such as the digital power supply,parallel current sharing and cooperative control system,a plasma cutting system scheme for thick plate based on MFC was designed,combining multiple plasma cutting power supplies and controlling them collaboratively to achieve the current parallel-sharing output that can promote the plasma cutting performance and dynamic response speed of system.Secondly,according to the performance requirements and technical indicators of the plasma cutting power system,plasma cutting power supply and the main circuit of the control cabinet are designed respectively.Using STM32 as the core of the minimum control system,the control circuit was designed to achieve the digital control of the cutting power supply and the control cabinet.Thirdly,a digital current sharing control strategy to solve the problem of current sharing control is proposed,which can achieve the parallel current sharing control between the multiple power supplies by CAN.And a cooperative control system scheme based on MFC control panel is designed,and the human-machine interaction interface and control program based on MFC is developed.With the CAN,The digital collaborative control of plasma cutting process for thick plate is realized.Finally,the experimental platform was set up to test the function and performance of plasma cutting system for thick plate.The performance of single plasma cutting power supply and the performance of plasma cutting system for thick plate with two parallel plasma cutting power supplies are tested.The results show that the system has high working efficiency,good dynamic performance and high current equalization degree of parallel system.Through the process experiment of plasma cutting 30 mm and 40 mm mild steel,it’s shown that the plasma cutting system is reliable with good cutting quality and meets the requirements of plasma cutting for thick plate.