Study On Repair Of Severe Non-Uniform Wear Guide By Laser Chromizing And Carburizing Strengthening Units

Remanufacturing is one of the important ways to realize sustainable development of economy,its essence is to repair the products which have been damaged or scrapped,so that their quality and performance can meet the requirements of reuse.Wear is the main cause of metal failure,and wear failure of the material surface is often hardness,stress distribution is uneven,this is because the material surface of different areas of wear is not uniform,that is,non-uniform wear.For example,machine tool guide surface due to long-term stress uneven,each region uses inconsistent frequency and so on the reason and so on uneven wear,the uneven wear generally exists in the guide rail from the beginning service to the scrap entire process,and along with the service life increment,the uneven wear degree presents the gradual increment tendency,when the guide rail long in the relatively bad environment work,the surface will be a serious uneven wear,resulting in a large reduction in machine tool processing accuracy,and then scrap failure.At present,most of the repairs for scrapped rails are performed by treating the failure surface as a uniform surface,ignoring the performance differences caused by non-uniform wear,adopting uniform mechanical means for overall repair or directly removing the non-uniform failure surface of the rails.It is not only a waste of manpower and material resources,but it also easily leads to difficulty in ensuring the dimensional accuracy in the height direction and increasing the difficulty of repair.This article addresses the problem of uniform wear resistance of non-uniform wear parts and uses rails with severe non-uniform wear as the research object.Due to inconsistent levels of wear in different areas of the rail surface,we need to make differential repairs in laser bionic coupling.The hard phase formed after laser processing is often referred to as a unit body.By changing the shape and distribution density of the unit body,a variety of biomimetic coupling models with different wear resistance can be obtained.Therefore,laser bionic coupling technology is gradually applied to non-uniform wear.Failure surface repair studies.The unit body obtained by laser fused treatment is called a fuser unit body,but its repair ability is limited in areas where the track surface wears more seriously.Therefore,for the repair of severely non-uniform wear guide rails,we need to prepare bionics with stronger wear resistance.In the unit body,the content of Cr and C elements in the unit body is respectively supplemented by laser alloying and laser carburizing,and a Cr-enhanced unit body and a carbon-enhanced unit body are obtained,and the micro-characteristics and performance analysis of the unit body are found.Both of the crystal grains are clearly refined.M₇C₃ type carbides appear in the former.The wear resistance of LMU increases by about 27%to 30%.The iron and carbon compounds in the latter increase significantly,and the C content increases.High-carbon martensite is produced,and its wear resistance is increased by about 60%to 63%relative to LMU.In this paper,the method of hardness zoning is used to repair the surface of the guide rail,the surface of the severe uneven wear guide is divided into five hardness regions?I:250³50HV,II:350⁴50HV,III:450⁵50HV,IV:550⁶50HV,V:650⁷50HV?,and the bionic coupling model is designed and optimized by adjusting the material combination,bionic shape and element spacing,Six kinds of bionic coupling models with12%-15%difference in wear resistance were obtained:The point model of chromium-increasing unit body?LCRU-P?,the strip model of chromium-adding element?LCRU-S?,the point model of the carbon element?LCU-P?,the mesh model of the chromium-increasing unit?LCRU-M?,the mesh model of the chromium+carbon–increasing?LCBU-M?unit and the mesh model of the carbon-increasing unit?LCU-M?.The wear resistance of each model in different hardness zones was obtained by numerical fitting method.Taking the most serious wear area as the fixed datum and setting the wear-resisting target M=85%,the bionic coupling model for each hardness partition matching according to the Wear Resistance law is as follows:LCU-M,LCBU-M,LCBU-M,LCU-P,LCRU-S,and by adjusting the spacing of the inner unit of each partition,the precision of the repair is further improved.In this paper,the experimental results are compared with the theoretical values and the error is 3.62%,which proves the effectiveness of the method.