Research On The Influential Factors Of Tool Failures In High Rotational Speed Milling Of Rosewood

Rosewood is difficult to be fabricated because of its characteristics of high rigidity,high strength and anisotropy.Tool failures including normal tool wear,crack on the edge,the tool nose broken and tool rod broken are often occurred during rosewood machining.If tool failures occur frequently,they will make the machining process interrupted frequently,reduce the efficiency of machine tools and increase the cost of production.Therefore,the research on the influential factors of tool failures in high rotational speed milling of rosewood is significant both in theory and in practical application.Using the methods of experiment and theoretical analysis,this paper studies the tool wear,cutting force and cutting vibration which can affect tool failures in high rotational speed milling of rosewood.The results show that(1)the wear happened on the clearance face and rake face of both the TIN tool and uncoated tool at the same time.There was no typical crater wear of metal cutting on rake face.Coating flaking occurred in TIN coated cutting tool and tipping occurred in non coated double-edged straight groove.The fretting wear mechanisms of both the TIN tool and uncoated tool are adhesion wear,abrasive wear and oxidation wear.Therefore,it is necessary to improve the TIN coating technology and increase the wear resistance and toughness of the tool.(2)With regard to the uncoated tool,the tool wear and cutting vibration acceleration increase with the increasement of spindle speed,feed speed and axial depth of cutting.The component of cutting force increases with the increasement of feed speed and axial depth of cutting.When spindle speed increases,X-axis cutting force increases,Y-axis cutting force decrease and Z-axis cutting force increases at first,then decreases after reaching 16000r/min.(3)The spindle speed plays the most dominant role in the cutter wear,followed by feed speed and the axial depth of cutting is the least one.The X-axial cutting force and Y-axial cutting force are mostly influenced by the axial depth of cutting,followed by the feed speed,and the spindle speed has the least influence.As to the Z-axial cutting force and cutting vibration acceleration,the spindle speed has the most dominant role in them,followed by the axial depth of cutting and the feed speed.By minimizing the tool wear,component of cutting force and cutting vibration,the optimal combination of the spindle speed,feed speed and axial depth of cutting is obtained the models of tool wear,XYZ cutting force and cutting vibration acceleration are established.(4)The typical signal analysis of cutting force shows that the XYZ cutting forces are in periodical fluctuation as sine curve.The test of different processing stages about cutting system shows that the first three processing stages is 24.4Hz,106.9Hz,195.7Hz,respectively.Therefore,the spindle speed near these three frequencies should not be chosen in order to avoid resonance in rosewood cutting which can accelerate the tool failures.