Blank Error’s Effect On Cold Drawing Transmission Shaft’s Precision And Simulation Analysis Of Die Diameter Control

Cold drawing blank’s tolerance is generally lower than IT14, the drawing accuracy is difficult to achieve higher requirements(lower than IT8) if directly drawn it one time. In order to improve the drawing precision, one way is measuring and grouping the blank, than using different die to draw, certainly, It will increase the workload and the number of die; the other way is drawing more than one time, it will affect the efficiency and the cost.The article bases on drawing 30 transmission shaft, research the regularity that blank error on the cold drawn transmission shaft’s forming accuracy, put forward a kind of variable diameter mould, through the ANSYS Workbench platform to simulate、analyse the process of transmission shaft’s cold drawn,find control method to improve the precision of cold drawing.For the same batch blanks 32..,simulate the process of cold drawn under the conditions that the pretreatment process(pickling, phosphating, saponification) and the die( 30) have been optimized, the results show that: the smaller the blank’s diameter, the smaller the cold drawing forming error, conversely, the greater; due to blank error, cold drawn transmission shaft’s diameter error range 16 um to 47 um.Then simulates the process that the blanks 32.. draw in the different diameter die, the results show that: drawing different diameter blank by appropriate diameter die can greatly reduce the cold drawing forming error, for the blank 32,using 29.98 mould to draw it, the forming error is 16, it reduces 53 percentage compare to using 30 mould.Through the ANSYS Workbench platform, analysis the diameter’s change of variable diameter mould(the material is ER5 steel) when give different radial pressure on it at the static condition, the results show that: the deformation of mould’s diameter ranges 25 um to 36 um when the pressure rangs 30 Mp to 50Mp; in a certain range, the greater the pressure, the greater the deformation of the die’s diameter, then the cold drawing forming error of drive shaft reduces,when the pressure is 30~40Mp, the error’s decrease is 10~15um when drawing the 30 transmission shaft.Through the orthogonal experiment method, simulate and optimize the main technical parametersmain(the length of diameter zone Ld、entrance angle α,、the interval between diameter zone and concave L), the results showed that: the three parameters’ effect order to variable diameter mould cold drawn is : the interval between diameter zone and concave L > entrance angle α > the length of diameter zone Ld; after optimization, the optimal combination of parameters is: the interval between diameter zone and concave L=4mm, entrance angle α=12°, the length of diameter zone Ld=5mm, simulate and analysis these results, it showed: for the different blank 31.6 32.0 32.4, respectively Apply different pressure of 10Mp、20Mp、30Mp, the transmission shaft’s forming error of cold drawn are 21um、20um、18um, it reached IT7 level precision.