Research On Influence Of Axial Forced Vibration Of CFRP Side Milling On Machining Quality And Control Methods

Carbon Fiber Reinforced Plastics(CFRP)is a kind of material which is lightweight,highstrength,and performance-designable.In recent years,it has been widely used in high-end devices such as aerospace vehicles and high-speed railway.CFRP components often achieve material-structure integrated manufacturing in a near-net-shape manner.However,in order to meet the stringent size,shape and position accuracy requirements of high-end equipment components,a large amount of side milling processing is still intensively required before assembly.In an effort to reserve enough space for the tool to pass,the components often need to be suspended from the clamping tool for a certain distance to form a cantilever clamping state during the side milling process.In this clamping form,because of the workpiece to be milled is less constrained in the axial direction of the tool,the workpiece is prone to obvious forced vibration in this direction under the action of the tool cutting,that is,"axial forced vibration".This vibration will directly affect the force state of the fiber in the CFRP under the action of the tool.This makes the co-removal process of fiber and resin more complicated than during stable cutting,in turn,it brings greater difficulties to the formulation of CFRP lowdamage milling processes.In response to this problem,this paper has been established CFRP cutting simulation models that take into account the effect of vibration along the tool axis through the micro-level of fiber and resin removal,and the effect of vibration on the removal process of CFRP material was studied.Based on this,for typical milling tools,a milling process plan with reasonable amplitude control was developed to further improve the milling quality of CFRP components.The specific researchs are summarized as follows:(1)Based on the CFRP milling surface morphology,the sensitivity of the CFRP side milling quality in the typical fiber directions to the axial forced vibration has been compared and analyzed.It is found that 135° is significantly more affected by the vibration than other typical fiber angles.Considering the difference in the axial restraint effect of the CFRP surface layer fiber and the middle layer fiber when they are cut,the micro-cutting models of the CFRP surface layer and the middle layer in the direction of the sensitive fiber under vibration has been established respectively;(2)The CFRP comprehensive milling experiment platform has been rebuilt to realize the "force-vibration" integrated online measurement.Through experiments and simulation methods,the influence of axial forced vibration on the quality of CFRP side milling has been comprehensively analyzed.That is,vibration could disperse the bending deformation of the middle layer fibers in multiple directions,so as to avoid excessive deformation and inhibit surface cavity defects.As for the surface fiber,vibration will aggravate its deformation to the weaker restraint side,and aggravate burr and tear damage;(3)According to the influence of axial forced vibration on the quality of CFRP side milling,for straight-edge milling cutters commonly used in engineering for milling CFRP,process experiments have been carried out to determine that it can improve the quality of the intermediate layer surface milling,and also avoid the axial amplitude range caused by surface damage.On this basis,for CFRP workpieces with different cantilever lengths,by optimizing the radial feed speed and cutting depth of the tool,a reasonable CFRP vibration control process plan was formulated,which effectively improve the quality of side milling;(4)For the special low-damage milling tool for CFRP—multi-tooth milling cutter,the difference in material removal form with straight-edge milling cutters has been analyzed;the amplitude range for improving processing quality has been determined,it is found that appropriately reducing the rake angle of the right-handed edge can increase the length of the left-handed edge to participate in the cutting,and the vibration suppression effect is better and the processing efficiency is improved.By optimizing the feed speed and cutting depth,a vibration control technology scheme suitable for CFRP workpieces with different cantilevers has been worked out.