The Study On Laser Cladding Forming Technology Of Two-Dimensional Gradient Material Cutting Edge

Die cutting tool directly determines the performance of die cutting equipment,large size rotary die cutting tool usually adopts integral milling or insert forming method,easy to appear material loss,high scrap rate,poor reliability and other problems,the main reason is the blade hardness is not enough,poor wear resistance,and high wear-resistant material forming difficult to control the reason.High performance blade requires high toughness,deformation and fracture resistance,and high hardness of the blade,wear-resisting without breaking.According to the performance requirements of the die cutting tool edge,the core and the external forming process were studied,and finally realized the two-dimensional gradient material edge laser cladding forming.Firstly,the existing tool material high-speed steel is selected as the core material.The effects of laser power,scanning speed and lap rate on micro-structure,residual stress and micro-hardness of high speed steel multichannel lap cladding were studied by orthogonal test.The results show that there is an obvious bright white band between the cladding layer and the substrate,and the cladding layer has a good metallurgical combination with the substrate.From the matrix to the heat-affected zone to the cladding layer,the micro-hardness increases gradually.Taking the micro-structure of cladding layer with no obvious defects and small residual stress value as the evaluation index,the optimal process parameters of a group of high-speed steel multi-channel lap joints were determined to be 1100 W laser power,100mm/s of scanning speed and 30% lap rate.Secondly,according to the requirements of surface properties of cutting edge with good wear resistance and high hardness,the comparative cladding of tungsten-nickel cemented carbide,tungsten-cobalt cemented carbide and tungsten-cobalt-molybdenum-nickel cemented carbide powder was carried out by compounding three kinds of cemented carbide powder.Determination of the optimum technological parameters and powder ratio of cemented carbide with micro-structure without defects and hardness as evaluation indexes.The results show that there are obvious defects in the cladding layer of tungsten-cobalt cemented carbide,the hardness of tungsten-nickel cemented carbide is less than 75 HRC,and the hardness oftungsten-cobalt-molybdenum-nickel cemented carbide cladding layer is not satisfied,the micro-structure of tungsten-cobalt-molybdenum-nickel cemented carbide cladding layer The wear resistance of tungsten-cobalt-molybdenum-nickel cemented carbide cladding layer and high-speed steel cladding layer is compared with that of high-speed steel.The wear resistance of the cemented carbide is 4.03 times higher than that of high-speed steel.Finally,tungsten-cobalt-molybdenum-nickel cemented carbide is selected as external material.Thirdly,two kinds of materials and processes inside and outside the two-dimensional gradient edge were determined,and the two materials were used to study the lap bonding of different materials.The influence of different splicing rate and sequence on flatness and residual stress of lap zone is studied.The research on macro surface shows that the heat and cooling of cemented carbide cladding layer will be uneven because of lap bonding and high speed steel cladding,after cladding cemented carbide first,and then lap high speed steel,the heat and cooling of the cladding layer of cemented carbide will be uneven because of lap bonding and welding sequence.After thermal expansion,thermal deformation results in cracks,and cracks appear in the lap zone.First cladding high-speed steel,then lap cemented carbide,because the high-speed steel has high heat resistance and heat hardness,small deformation,no obvious defects in the cladding layer;when the bonding rate is 40%,the effect of cladding is the best.Finally,on the basis of obtaining the research and control method of lapping,the two-dimensional gradient cladding layer is prepared,which accords with the requirement of triangle shape and has no obvious defects,and the hardness changes gradients from inside to outside.Meet the requirements of gradient cutting tools,can provide a new method for large-size rotary die-cutting machine tool blade manufacturing.