Study On Forming Process Of 5A06 Aluminum Alloy Concave-bottom Cylindrical Parts With Rigid-flexible Composite Deep Drawing Temperature

With the aerospace and rail transit and other fields of equipment parts structure lightweight,precision forming and composite forming technology requirements are higher and higher,coupled with the continuous optimization and upgrading of aviation sheet metal components in structural design,the shape of the required components is more complex and the forming requirements are more stringent.5A06 aluminum alloy has good corrosion resistance and no low temperature brittleness.However,when forming complex thin-walled parts,the surface forming quality of the alloy is poor and the forming performance is limited,which has become a difficult problem.The traditional liquid filling drawing is difficult to achieve one-time accurate forming,resulting in low manufacturing accuracy and low production efficiency.In order to improve the bottleneck problems such as insufficient clamping accuracy and poor forming quality in the local area of aluminum alloy concave bottom cylindrical parts,a rigid-flexible composite drawing warm forming process solution was proposed.Taking aluminum alloy concave bottom cylindrical parts as the research object,the influence of key process parameters on the forming quality of parts was explored by combining numerical simulation with forming experiment.The warm forming process of 5A06 aluminum alloy concave bottom cylindrical parts with independent liquid filling and rigid-flexible composite drawing was numerically simulated.The effects of process parameters such as liquid chamber pressure loading path,preexpansion pressure,punch feed speed and friction coefficient on the forming performance and die bonding of the parts were investigated.The results show that increasing the pre-expansion pressure is helpful to improve the die bonding of the preform,but too large pre-expansion pressure will also aggravate the thinning of the sheet thickness.Different liquid chamber pressure loading paths have great influence on the forming results of liquid-filled drawing parts;in the rigid-flexible composite drawing process of sheet metal,the smaller the forming speed is,the higher the minimum wall thickness of the concave bottom suspension zone of the cylindrical part is.The lower the friction coefficient between the bottom of the punch and the upper surface of the sheet metal,the smaller the maximum thinning rate of the cylindrical part with concave bottom;the larger the friction coefficient between the back pressure die and the lower surface of the sheet,it is beneficial to reduce the radial tensile stress of the sheet,so as to improve the minimum wall thickness of the concave bottom cylinder.Forming experiments were carried out for the independent liquid-filled drawing and the rigid-flexible composite drawing of 5A06 aluminum alloy concave bottom cylindrical parts.The key process parameters that affect the forming quality are discussed,and the influence of different process parameters on the die-fitability of concave bottom is analyzed.By measuring the wall thickness of each mark point of the final forming part and calculating the die sticking rate of the concave bottom,the maximum thinning rate and the die sticking rate are taken as the evaluation indexes,and the liquid chamber pressure and the punch feed speed are taken as variables.Under the process conditions of liquid chamber pressure 20 MPa,sheet metal forming height50 mm and forming speed 1.8 mm / s,the maximum thinning rate of the wall thickness of the concave bottom cylindrical part is 21.3 %,and the die sticking degree is 97.3 %.