Design Of Control System For Hollow Ingot Electroslag Furnace And Research On Inner Mould "Bite" Problem

Due to its unique structure and solidification characteristics,hollow Ingot has obvious superiority in comparison of ordinary ingot,in the case of production of large cylinder forgings or large diameter thick walled pipe.As an effective technology for production of high quality hollow ingot,more and more attention is being paid to the electroslag remelting(ESR)process which will has wide application prospect.In this paper the control system of hollow ingot electroslag furnace has been designed and the methods for preventing the"bite" of inner mould have been established on basis of the experimental equipment and technology of ESR hollow ingot in the laboratory of the Northeastern University.The experiments have been carried out to verify the proposed scheme.A set of computer control system of the hollow ingot electroslag furnace has been developed with PLC controller as the core.The whole system consists of upper and lower computer structure.An industrial control computer and liquid crystal display(LCD)as the hardware of upper computer,and the WinCC as the software were applied respectively,which realizes monitoring of the electroslag furnace production process,real-time monitoring of various data and alarm information in the operation process,and provides data storage and print functions.S7-200SMART PLC as hardware of lower computer and STEP7-microwin smart as software to programming controller is used respectively,which is responsible for all the control actions of electroslag furnace production process.The connection between upper and lower computer is realized by an industrial Ethernet,and the connection between PLC and drive equipments or some detection devices is realized by Modbus communication.PID control algorithm is used to realize melting power control.The main problems existed in the production of hollow ingot by the conventional electroslag remelting process have been analyzed,and some solutions have been put forward in this paper on the basis of the investigation of ESR hollow ingot process.The double power source and tension sensor technology were used to solve the problem of inner mould "Bite".The designed control system and the improved scheme have been tested in practice.The experimental results show that the proposed scheme significantly improves the success rate of hollow ingot melting,effectively reduce the mould "bite" probability.The surface quality and internal quality of the hollow ingot produced by new process was excellent,with the compact crystalline structure and the high purity.