Research On Wear Detecting Of Superalloy Milling Tools

Nickel-based superalloys can maintain good stability and fatigue resistance even in high temperature environment,consequently,they are widely used in heat-resistant parts of aerospace engines,especially turbine blades and turbine disks.However,as a typical difficult-to-machine material,large cutting force as well as high cutting temperature is generated in conventional machining processes of nickel-based superalloys,which can cause serious tool wear.Moreover,excessive wear and damage of tools can easily cause deterioration of the surface quality of workpieces,affecting product processing quality and production efficiency.It will even destroy the machine tool and cause serious economic losses.To avoid the adverse effect of tool blunt,the tool is usually replaced after a fixed processing time.However,the speed of the tool wear varies greatly under different processing conditions.Advance of tool change will not only reduce the machining efficiency,but also reduce the tool utilization rate.Therefore,it is necessary to detect the wear condition of the tool in the machining process and change the tool in time before the tool reaches the blunt standard.In this paper,the tool wear detection system is designed by using machine vision technology.This system overcomes the shortcomings of the traditional tool wear detection method,and has the advantages of non-contact and high efficiency.Based on the established tool wear detection system,the surface milling experiments of nickel-based superalloys were carried out to verify the detection system,and the influence of tool wear on surface roughness was studied.The main research work of this paper is as follows:1.The key technologies of flank wear detection of milling cutters were studied.According to the wear characteristics of milling tools studied by domestic and foreign scholars,the evaluation index of blunt milling tools is proposed,that is,the maximum width of the flank wear of the milling tool and the wear area of the minor flank.2.Flank wear detecting system of the milling tool was designed,and the automatic detection of tool wear in the milling process,including the automatic acquisition of images and the automatic processing of images has been realized.The automatic image acquisition includes auto focusing and triggering the camera to take a picture,and can save the acquired image to a specified path;the automatic image processing realizes automatic image pre-processing,edge detection,sub-pixel detection and extraction of tool wear feature value.3.Coated carbide milling tools were used to carry out milling experiments of nickel-based superalloy,and the experimentally measured results were compared with the results obtained by the microscope to verify the performance of the tool wear detection system.The results show that the wear detecting system has a reliable detection precision and can be used to monitor the wear of the milling tool.4.The effect of tool wear on the surface roughness was investigated.It was found that when the flank wear width is within a certain range,the tool wear has little influence on the surface roughness and morphology.When the flank wear width exceeds a certain critical value,resulting in a sharp increase of the surface roughness value,and pits appear on the surface topography of the workpiece.