Research On The Cutting Performance Of Stone Plastic Composite(SPC)

Stone plastic composite(SPC),as a new engineering material,is mainly made from the mixture of stone powder,polyvinyl chloride and additive processed by a hot press.Recently,SPC has been widely used in the fields of decorating,flooring,wall tile and so on,becase of its excellent material performance.In the industrial machining,SPC is shaped into flooring by sawing,milling,and planing equiements with corresponding cutting tools.However,there are still some deficiencies during SPC machining,such as low production efficiency,poor cutting surface quality,low form and position tolerance,severe tool wear,and high power consumption and production cost.Furthermore,according to the literature review,no systematic research has focused on the cutting performance of SPC.Thus,in order to solve the problems existed in SPC machining,the cutting performance of SPC was systematically investigated,mainly focusing on the trends of the chip deformation,cutting forces,cutting heat(temperature),cutting quality and tool wear in terms of cutting methods,tool angles and cutting parameters.On the research of SPC chip deformation,SPC orthogonal cutting model was developed by using finite element method with respects of material constitution,damage,chip separation,contact friction,heat conduction and so on.Meanwhile,planing experiment was performed to explore the changes and periodic trends of cutting forces,heat,stress and strain fields by using high-speed camera,dynamometer,thermal infrared imager and surface roughness tester.Finally,the mechanism of SPC chip deformation was revealed by exploring the generating principle of different chip produced in thermo-mechanical coupling,the results are obtained as follows: In the cutting process of SPC,chips can be divided into four categories,mainly including ribbon chip with continuous and spiral shape,serrated chip with irregular particle shape,blocky chip with continuous serrated shape,and granular chip with irregular granular shape.During the deforming processes of SPC chips with different shapes,the cutting process when genering cracking chip has the highest cutting force and fluctuation,followed by blocky chip,serrated chip and ribbon chip.While the cutting process releasing ribbon chip has the greast cutting quality and stability,followed by serrated chip,blocky chip and cracking chip.In general,when ribbon chip is formed,the cutting process has the greast performance during SPC machining.On the research of SPC cutting force,temperature,quality and tool wear,the reasonable tool geometries and milling parameters were obatained based on the results of SPC chip formation.Diamond milling experiments were carried out by response surface method,binary method and micro analysis technology through dynamometer,thermal infrared imager,3D surface measuring tester,scanning electron microscope and energy dispersive spectrometer,mainly discussing the effects of cutting methods(straight-tooth milling,helical milling and tapered milling),tool angles(rake angle,helical angle and taper angle)and cutting parameters(spindle speed,feeding rate and cutting depth)and on the responsing results(cutting forces,temperature,quality and tool wear).Then,the related models were devolped by analyzing the influencing significance of each factor and interaction effects on the results.Finally,the damage of machined surface and tool wear mechanisms were revealed by observing the surfaces of SPC and cutters,and the SPC optimum cutting conditions were determined based on optimization,the main results are shown as follows:(1)Quadratic polynomial regression models were developed in terms of cutting force,temperature and surface roughness.Meanwhile,those models are proposed to be adopted to predict and optimize the actual cutting force,cutting temperature and surface roughness during SPC machining;(2)Vertical wavy stripe was observed on the SPC surface machined by straight-tooth and tapered cutters,while machined surface showed inclined wavy stripe when milled by helical cutters.Both in straight-tooth,helical and tapered millings,the surface damage is mainly distributed in the crest and two axial sides of the cutting wave,and the damage patterns of SPC surface were cracking and pit.(3)During SPC milling,flank wear of diamond cutters increased with the increase of rake angle of straight-tooth cutters and taper angle of tapered cutters,but decrease of helical angle of spiral cutters.Besides,both in straight-tooth,helical and tapered millings,it can be found that the pulling-out of grain,cracking,chipping and flaking observed on the tool surface when milling SPC,and their wear pattern were fatigue wear and adhesive wear.(4)Based on the optimization,the optimal cutting conditions for straight-tooth milling was rake angle of 10°,cutting speed of 37.9 m/s,feed per tooth of 0.32 mm and milling depth of 0.5 mm,the optimal cutting conditions for helix milling was helical angle of 70°,cutting speed of 51.3 m/s,feed per tooth of 0.24 mm and milling depth of 1.1 mm,and the optimal cutting conditions for tapered milling was taper angle of 75°,cutting speed of 46.2 m/s,feed per tooth of 0.26 mm and milling depth of 0.5 mm.(5)Helical cutters have greater durability,stability and material removal rate than helical and tapered cutters,which is advisable to be used in SPC rough machining for great tool life,cutting stability and material removal rate.Meanwhile,the cutting quality machined by tapered cutters is greater than those of straight-tooth and helical cutters,thus tapered cutters were proposal to be applied in SPC fine machining in terms of high cutting quality.This paper firstly investigated the cutting performance of SPC.The results of this paper enrich the theory knowledge of cutting principle and tool application,and provide theoretical guidance and scientific basis for SPC industrial machining.