The Fracture Failure Analysis Of Extrusion Dies For Steel Wheel Balancers

Wheel balancer is a kind of indispensable automobile parts. As a kind of high quality,efficiency, low consumption production technology, extrusion technology has been used inthe industrial production of steel wheel balancers. Extrusion is able to produce dozens ofpieces per minute. However,because the billets for wheel balancers is made of carbon steel,the extrusion die will bear huge stress in process of extrusion production. Thus, the failureof extrusion dies is inevitable and the early failures of extrusion will cause huge losses forenterprises, among which fracture failure is the mainly and the most dangerous early form.This paper analyzes the fracture failure of extrusion die through a system study ofexamples, studies the reasons of fracture failure, and put forward the correspondingimprovement measures.The beginning part is an analysis of the fracture combing the specific workingconditions. After making sure that the form of fracture is fatigue fracture, a further analysisof such kind fracture failure will be carried out. problems can be analyzed from twoaspects including the mechanical performance of material and the stress status. Thematerial mechanical properties of the die would affect the working life of the die directly.Instruments such as the microscope, scanning electron microscope, and energy dispersespectroscopy and so on are applied to explore the matrix organization, mechanicalproperties of the die materials. Test results show that the hardness of the material is uneven,there are a lot of large-size carbides in the steel and the alloying elements in steel areunevenly distributed. What’s more some the content of kinds of alloying elements in steelis out of limit. All these lead to the poor impact toughness of the material.The stress levelis closely related to die life. What’s more, during the extrusion process, the stressdistribution and variation are complicated and difficult to actual measured. In this paper,the DEFORM software is applied to simulate the extrusion process of steel balancers andchange the set of process parameters of Finite Element Simulation to analyze the die stressunder different conditions and explore the linkages between the extrusion technology andfracture failure on basis of examples. Orthogonal experiments with multiple parameters and levels should be made to rank the process parameters affecting the die’s stress and thusget the optimum parameters constitute.The conclusion made through an analysis of the extrusion die fracture is that thefailure form of the extrusion die is fatigue fracture and the material is the main factorleading to the failure. The numerical simulation has high credibility and stressconcentration is the immediate cause of early failure of the die and the actual fracturefailure happens in the high stress area of numerical simulation. Actual productionverification shows that strict control over the mould‘s materials and optimizing processparameters to improve the stress conditions of such cold extrusion moulds will have goodeffect on extending the service life and preventing early fracture failures.