Study On Forming Process Improvement Of Reinforcing Plate Of Front Subframe

The research object of this paper is the reinforcing plate of the front subframe on Jiangling Lufeng X7 car.This part is left-right symmetrical.This paper takes the left reinforcing plate as the object.The overall dimension is about 320 ×238 × 55.4 mm.The plane contour is in an L-shape with an average width of about 75 mm.It is a narrow flange shallow drawing / flanging part made of DC01 steel(equivalent to #10steel)plate with a thickness of 1.5mm.There are steps with inclined transition but large drop as a whole,which need to be combined with shallow drawing / flanging and bending deformation.The forming process of a company adopts large process supplement surface,the material utilization rate is 25%,the maximum thinning rate is27.6%,and the contour size of the die is large.In this paper,the rationality of the original forming process is questioned,and a deep drawing forming scheme without process supplementary surface is proposed.The blank shape was improved,and the material utilization rate was increased to58%.The numerical simulation test is mainly carried out with the help of DYNAFORM software.The problems of flange wrinkling and bottom wrinkling in bending area exposed in deep drawing are explored.It is found that the reason of bottom wrinkling in bending area lies in the limitation of part structure.In order to solve this wrinkling problem,the experiments were carried out with four factors as variables: blank holder force,stamping speed,friction coefficient and die clearance.The results show that larger blank holder force and stamping speed can inhibit the wrinkling at the bottom of the bending area.Taking the maximum thinning rate and maximum thickening rate as evaluation indexes,9 groups of orthogonal experiments were carried out to obtain the best combination of factors.However,the factor combination with the maximum thinning rate as the main evaluation index will produce heavy wrinkling at the bottom of the bending area,so it is necessary to increase the blank holder force on the basis of the best factor combination.Then the scheme of pre punching the blank is put forward,which can reduce the maximum thinning rate to 21.7% within a certain blank holder force range,which verifies the feasibility of deep drawing without process supplementary surface.Two sets of drawing / flanging dies with simple structure and small outline size without process supplementary surface are designed(for enterprises to choose).Both sets of dies take into account the influence of lateral force on the die in the forming process.The single action die is mainly borne by the punch fixed on the lower die base,and the lock catch is used in the double action die.A differential drawing die is also designed.The numerical simulation shows that the differential forming scheme can avoid the wrinkling at the bottom of the bending area and only needs a small blank holder force.The research results of this paper can provide reference for the forming process and die design of stamping parts with similar structure.