Research On Hydro-mechanical Deep Drawing Of The Cups Of Conical Bottom

The lubricating oil container of some equipment was welded together by two parts,named as the left and right housings of the oil tank,which were formed in advanced.The left and right housings of the oil tank are conical cups.In order to improving the quality of the formed parts,the hydro-mechanical deep drawing method will be adopted to form this type cups instead of the common way used in the plant.First of all,5A02-O aluminum alloy sheet properties were tested and evaluated according to the deformation characteristics of the part.On the basis of this result,a feasible forming scheme was decided.Then,the forming process window of hydro-mechanical tapered conical parts and influences of the key parameters on hydro-mechanical deep drawing was obtained by simulating and analyzing the process.Finally,hydro-mechanical deep drawing experiment was carried out according to the simulation results.Consequently,the simulation results were verified and qualified products were obtained.The main results are as follows:(1)The main part is conical cup.Cone angle of cone bottom part is 55 degree and the relative height is about 0.19.The cone bottom is a shallow conical part with a high straight wall it which is difficult to manufacture using conventional stamping process.Through hole expanding test,limit expansion rate of 5A02-O aluminum alloy plate is measured to be 51%;Pre-deformation can decrease the plate material expansion rate;After forming of main body parts,the subsequent reaming capacity will decrease due to plastic deformation at expansion site.It is necessary to adopt annealing treatment or special forming process when expand hole.(2)Based on the Dynaform5.7 finite element software,the finite element simulation of the filling and drawing process of the conical cup is carried out.The two turning point of hydraulic loading path maximum pressure constant as the loading path of tapered cylindrical parts,and studies the relationship between inflection point and punch stroke,found the conical cup drawing pressure loading process window;To optimizing the loading path of different cone angle of the conical cup is studied study on the different cone angle,conical cup rupture risk with cone angle conversion.The results show that:(a)The liquid pressure loading path of the 2 inflection points is suitable for the conical cup hydro-mechanical deep drawing.The first turning point is the moment while the punch tip corner center move to the horizontal line that the die corner center located on.The second inflection point is the moment while the punch transition region fillet center move to the horizontal line that the die corner center located on;(b)For the half cone angle is 25-55 degrees within the scope of the tapered cylinder,rupture of dangerous point at the corner of the punch;The half cone angle of 55-75 degrees in the tapered conical parts,fracture zone of hydro-mechanical drawing in the cone wall and straight wall at the joint parts here the thick wall hydro-mechanical deep drawing of the thin.(3)In order to verify the results of the finite element simulation analysis,the experiment on the filling of the right shell of the helicopter oil tank was carried out.Experiments show that when the blank holder force is too large,the parts tend to appear thinning and breakage.When the blank holder force is too small,it is easy to produce wrinkling or insufficient drawing.The results of the experiment and the finite element simulation are basically consistent,and the conical cup which meet the quality requirements are successfully drawn.