Electric Discharge Machining Process Research For Serrated Axle Cold Extrusion Mould

As a kind of machining method which need less energy,less material and with better effect.Cold extrusion manufacturing process has positive effect on improving product accuracy and reducing cost.So most automobile corporation attract attention on it.Steering serrated axle is an important transmission component in vehicle industry.In vehicle steering system,using spline to connect different parts has many advantages,such as large contact areas,high carrying capacity,good directional.And compared with gear,spline has shallow root,strains can't be concentrated,so spline has long working life.Generally,steering serrated axle is made by metal,and metal cold extrusion has characteristics as below: high material intensity and high deformation resistance;high cold hardening sensitivity,as cold hardening sensitivity is directly proportional to extrusion force,if handle unproperly,mould will be damaged;plastic forming will make metal particle stick on mould,and cause damage on the surface of mould and workpiece.Also cold extrusion mould has some requirements as below: mould working parts should be designed with smooth fillet,to avoid strains concentrating;mould working parts should be made by material which has high strength and stiffness;keep enough compression areas between up and down baseplate;baseplate should be made by medium carbon steel which has high strength and stiffness;mould vulnerable component should be exchanged conveniently.To deal with these cold extrusion characteristics,some process strategy will be taken as below: use reasonable heat treatment process to soften cold extrusion metal blank;use phosphating surface process and lubricating to reduce unit extrusion pressure;optimize mould construction which can disperse extrusion force;use ideality cold extrusion mould steel.This paper use electric discharge to machining cold extrusion mould to improve components precision.As it is different from cutting machining,electric discharge is a non-contact machining method.It has great superiority on machining extrusion mould.Most studies of electric discharge biology,parameter selection and technique have important significance on product precision controlling.This paper combine traditional manufacturing industry,statistics and computer software,use finite element method to analyse electric discharge physical characteristics,use orthogonal test to choose parameters.This research help mould machining to avoid many duplicate tests.Via computer simulation,various boundary conditions and parameters can be confirmed in early time.So manufacture economic cost can be reduced greatly.The final processed mould fit the expectation,its surface roughness controlled within 3?m,its dimensional accuracy also controlled within 0.03 mm,this make a great improvement than cutting machine work.And also,this mould made successfully at the first time,avoid repeated trial manufacture.So the result prove the feasibility of this research.