Research On The Electrically Assisted Flow Spinning Process Of 30CrMnSiA Cup-shaped Parts

The 30CrMnSiA alloy steel cup-shaped parts is a prefabricated material for the preparation of harmonic reducer flexible wheels,engine inner gear rings and other power transmission and load-bearing core components.Thin-walled cup-shaped parts is usually manufactured by forging and cutting technology,and the materials need heat treatment in the process,the process is more complicated and there are some shortcomings such as unstable parts quality.The plasticity of 30CrMnSiA is poor at room temperature,and its low formability makes it more difficult to manufacture.The electro-plastic effect of metal is widely used in plastic forming,and the flow spinning process is one of the effective methods to produce high quality thinwalled cup-shaped parts.Therefore,the 30CrMnSiA thin-walled cups were manufactured by the electrically assisted flow spinning process.In this paper,the cup blank after deep spinning is studied,according to the theory of heat transfer and electric contact,which combined with the characteristics of the flow spinning tooling and the current application method of electrically assisted flow spinning is studied.Two current application schemes are designed,the test results show that the method of dynamic contact current applied to the blank is effective,it is universal in the manufacture of the whole flexspline;The tungsten-copper alloy with the advantages of resistance to electric wear and high temperature is selected as the contact material.Based on ABAQUS/Standard platform,the 30CrMnSiA cup-shaped parts electrically assisted flow spinning finite element model was established,the regular of flow spinning forming was analyzed.During the process of preenergizing,the blank temperature was evenly distributed in the circumferential direction,and the blank temperature gradually increased along the feeding direction of the rotary wheel,with the maximum temperature at the blank mouth;radial spin pressure > axial spin pressure > tangential spin pressure in the process of flow spinning;As the preelectrification time is longer,the maximum value of three-way rotary pressure decreases.With the increase of feed ratio and single-pass thinning rate,the three-way rotary pressure increases.The test of electrically assisted flow spinning is carried out,the common defects and preventive measures in the test are discussed.In the electrically assisted flow spinning test,the wall thickness deviation of the spinning part decreases gradually with the increase of the total thinning rate,but the roundness was increased;By reasonably setting current parameters and preenergizing time,ensuring smooth contact surface and controlling spinning distance and trace thinning rate,the "electric spark" can be effectively reduced and the spinning defects can be eliminated.The response surface test scheme of two section thick cup-shaped parts was determined,and the process parameters of electrically assisted flow spinning of thin wall cup-shaped parts were optimized.The amount of current and the amount of trace thinning have significant interaction with the wall thickness deviation,the preenergizing time,the roundness of the spinning part and the straightness of the spinning part.According to the prediction of forming quality of spinning parts by ga-bp and the optimal process parameters of thin-walled cup parts manufactured after GA optimization,the current size of 1211.8A,the pre-electrification time of 63.58 s,the feed ratio of spinning wheel 0.411mm/r,and the first-pass thinning rate of 29.87% were proposed.