Optimization Design Of Cold Extrusion Process Parameters For Multi-ribs Aluminum Alloy Part

Multi-ribs aluminum alloy parts are widely used in aerospace,automotive and rail transit fields.These parts have the characteristics of thin wall and high rib,and many problems will be encountered in the process of forming such parts.The aluminum alloy billet is obtained by the forging method,and then the ribs are processed by the numerical control method,there will be problems such as unsatisfactory metal filling and stacking,and the cost is too high.When manufacturing such parts using welding and casting methods,problems such as shrinkage cavities and excessively coarse material grains are prone to occur.Multi-ribs aluminum alloy parts often have the advantages of dense structure distribution,higher precision,better surface quality,and excellent mechanical properties,and can be used as high-quality structural parts.In this paper,the cold extrusion forming process of multi-ribs aluminum alloy part was studied,and the simulation scheme of forming target part by closed cold extrusion in one process was proposed.By analyzing the influence of some key parameters on the forming process of target part,reasonable process parameters were selected to obtain the full and qualified part,and the design of cold extrusion die was completed,which can provide an effective reference for the process parameters design in the cold extrusion of such multi-ribs parts.The one-step forming scheme simplifies the processing procedure and can greatly cut down production costs.The main research contents of this paper are as follows:1.The basic theory of metal plastic forming that needs to be used in the analysis of cold extrusion for multi-ribs aluminum alloy part was introduced.The process scheme of cold extrusion for multi-ribs aluminum alloy part was formulated and the process parameters to be explored were determined.The finite element modeling process of aluminum alloy cold extrusion part was introduced,including creation of geometric model,selection of material model,creation of analysis step,creation of interaction,creation of boundary condition and creation of meshes.2.The influence of die structure parameters on the cold extrusion results of multiribs aluminum alloy was studied.The effects of five die structural parameters on the forming results were studied separately,including the shape of outer ribs,the inner diameter of the counter bore,the angle of the punch end,the angle of the outer ribs and the depth of the counter bore.The specific research objects include the extrusion force required in the forming process,the equivalent stress and strain on the part.The flow law of the billet metal during the cold extrusion forming process of the multi-ribs aluminum alloy parts was obtained.The part structure is determined: the width of the outer ribs of the part is 6mm,the thickness of the outer ribs of the part is 4.23 mm,the inner diameter of the counter bore is 17 mm,the angle of the punch end is 6°,the angle of the outer ribs of the part is 9°,and the depth of the counter bore is 6mm.3.After determining the shape of the formed part,the effects of friction condition parameter,extrusion speed parameter and corner radius parameter on the cold extrusion forming results were studied separately.By analyzing the forming results including the extrusion force required in the cold extrusion process,metal flow rate and the equivalent stress and strain on the part,the three process parameters in the cold extrusion for multi-ribs aluminum alloy part were optimized.Finally,the optimized process parameters are as follows: the friction coefficient is 0.1,the extrusion speed is10mm/s,the corner radius of the punch end and the corner radius of the die outer ribs are both 1.5mm.4.According to the force analysis of the die,the double-layer composite die was designed.Through the stress analysis of the combined die,it was found that the maximum equivalent stress on the die at the end of the cold extrusion did not exceed the allowable strength of the die material W6Cr4Mo5V2.The designed die met strength requirement of the cold extrusion process,and the cold extrusion die assembly drawing was designed according to the simulated process parameters.