Study On Extrusion Wheel Service Life Of Continuous Extrusion Machine

Extrusion wheel is a key die in the continuous extrusion forming Machine,because of its work under Comprehensive role of pressure, thermal stress and friction, so has high requirements to the die materials, demanding moreStrength and toughness, generally, we selected hot work die steel of H13 as the continuous extrusion wheel's material, but some of them have the low life,damaged in adnormally failure, a serious result in reducting production efficiency and increasing production cost.Analysys the reasons for its early failure hasa great guide for further improve the extrusion wheel manufacturing process.This text around extrusion wheel life this problem,primarily from failure analysis materials and force to study.First,failure analysis to non-normal damage fracture. Collecting fresh fracture sample from continuous extrusion production. Optical microscope and scanning electron microscope and other instruments were carried out Macro-examination, chemical composition analysis, hardness testing, microstructure examination and fracture analysis on the cracked die. Experimental results show that the extrusion wheel groove have visible machining scratches in the surface, and first formed thermal fatigue crack in the scratch, source of crack initiation, the extrusion wheel happened fatigue fracture under the high stress concentration.Then, study on the process of fracture under stress.Combination of extrusion wheel force in the actual production situation,estabblish ANSYS finite element model to analyze the stress and deformation in the wheel groove and keyway position which in the normal work force state,come to the work area at the extrusion wheel gauge quick access to parts of the stress has the largest stress, round groove has deformed on this stress, a alternate loading work on non-working and working area which consistent with the actual site of fracture.Finally, acorrding to the relationship between crack iniation expansion and microstructure, to research on extrusion wheel's miscrostructure and properties. Mainly to do comparative analysis with ultrafine material's microstructure and properties, comparing the difference of miscrostructure and properties between the them, and analyze the main reason to improve the extrusion wheel's material.Lower tempering temperature can significantly improve the extrusion wheel strength,toughness decreased slightly.