Research On Warm And Cold Combined Forming Process And Simulation Of Thin-walled Deep Cylindrical Pieces

The forming of thin-walled deep cylindrical pieces is one of the difficulties in forging industry because of the large deformation and complicated process.In recent years,with the development of warm/cold combine forming technology,it has been wildly used in high-strength steel,large deformation,high precision forming.The application of warm/cold combined extrusion forming process improved the quality of forgings greatly,reduce energy consumption in the production of thin-walled parts.This paper analyzes the characteristics of the thin-walled deep cylindrical pieces,and design the warm/cold combined forming process and mold.In the warm/cold combined forming process, a cup was formed in warm forming process and the thin-walled deep cylindrical pieces was forged in cold forming process.The warm forming process include upsetting,ironing,backward extrusion,the cold extrusion is ironing process.The entire forming process was simulated with Deform software.The simulation software provides convenience for program verification and process development.In the research of thin-walled cylinder warm forming,the status of billet temperature change,mold temperature field,mold stress and punch load were pointed out during the whole process simulation.The influence of worm forging and die wear on the main process parameters were analyzed.The result shows that:(1)If the initial temperature of thin-walled cylinder warm forming increased,the forming load dropped significantly,temperature of billet increased.The mold would be overheat when product on the low-speed hydraulic press.(2)When the degree of deformation increased,die stress was also increased,but the load was not directly proportion to the degree of deformation because the raising temperature of billet.(3)If the forming speed increased,the billet temperature raised and the temperature differences wasreduced,die stress decreased,forming load decreased first and then increased.(4)Friction factor has little effect on the billet temperature and the mold stress,but if increase the friction factor,load would increased significantly.(5)Die wear reduced when the initial temperature increased,increased when the degree of deformation and friction factor increased,increased slowly when the extrusion speed increased.Based on the above conclusions,semi-hot forming process was proposed.The new process was simulated.The result increased the product tact and reduced the energy consumption of processing.During the cold forging process,forming load,die stress and billet damage were simulated.Because of the large deformation degree and large deformation resistance the billet can not fully fit the mold.According to the product defects of cold forging,the process modification and optimization were put forward.Take the degree of product defects as the goal,The die angle and the value of billet turning was optimized design.The reasonable die angle ? and the turning value h are obtained, which not only eliminate the deformation defects but also reduce the forming load and the damage value of the parts.This subject comes from enterprise,the pilot production verification was taken in a precision forging enterprises.it shows that the process and mold design is reasonable and product size can achieve accuracy requirements.The results of this study have guiding significance for the actual production, and provides a theoretical basis for the manufacturing of related products.