Process Research And Numeircal Simulation Of Laser Cladding Fabrication Technology Feeding By Side

The laser cladding fabrication (LCF) with wire feeding by side is a new rapid prototypingtechnology. Basing on the principle of layered-stack, the technology can make metal partsaccording to CAD file inputted the control system by means of melting metal silk absolutelywith the process of wire feeding automatically, needing no mould and cutting tool. Thedensity of the metal parts is close to100%. In recent years, this technology has alreadybecome the research focus in the word. At present, there are two difficult problems ofcladding industrial metal parts directly. Firstly, the problems of thermal deformation, layercollapsing, hot crack and so on remains. Secondly, the study mostly focused on only specificsilk material, without establishing common solutions according to different silk materials orthe scheme of general silk material (such as carbon steel).In view of the above questions, this paper takes making dense metal parts directly withLCF using C45steel as the goal. The LCF system is developed and improved first. Then theprocess of cladding fabrication is researched systematically, in order to get an appropriateLCF scheme under the premise of getting dense metal parts. The main research contents andconclusions are as follows.(1) Firstly, the basic principle of the LCF technology was researched, laying a foundationfor the subsequent improvement of LCF system, and the following investigation on theprocess of LCF.(2) Developing and improving the LCF equipment with wire feeding by side. Discoverthe defects under the condition of knowing the existing function and characteristics of theequipment, laying a foundation for the subsequent improvement of equipment and furtherstudy. The equipment can make simple metal parts, such as thin parts, can not make complexmetal parts duing to the influence of such scanning direction, temperature accumulationfactors and so on.(3) The basic process of LCF is surveyed using C45steel. The effect of cladding qualityand efficiency caused by wire feeding direction and angle, wire feeding speed, laser scanningspeed and laser power is investigated, in order to get suitable cladding fabrication scheme.The microstructure and micro-hardness of the melt track samples is inquired to prove that the LCF can get dense metal organization, and the composition of the melt track is researched byobserving the energy spectrum. As long as the process parameters collocated reasonably, thetrack possessing dense metal organization and smooth surface can be obtained using LCFwith C45steel wire.(4) Through investigating the temperature field and stress field of the melt track bymeans of finite element simulation, the temperature and stress distribution can be gottenwhich can not be gotten without real time measurement and control system, laying afoundation for followed-up introducing feedback control system and controlling the thermaldeformation, hot crack problems and so on. According to the temperature distribution, thecolumnar grain generates expanding from center to around agreeing with the heat transferdirections agreeing with the experimental results. According to the temperature gradient, thetemperature spread fastest in the re-melting area, therefore fine grain generates, causing tohighest hardness value in this area directly, that agrees with experimental results. Accordingto the stress distribution, the thermal deformation of the melt track can be speculated, and thecauses resulting in hot crack and its area will be known.