High speed processing technology of graphite

2020-12-1731

        When making high-speed machining technology, the following aspects should be considered comprehensively: (1) cutting parameters; (2) cutting mode; (3) tool geometry; (4) number of cutting edges and overhanging amount of cutter bar; (5) cooling conditions; (6) clamping mode between tool bar and machine tool; (7) clamping mode of blade, etc. At present, some scholars in Japan and Germany have carried out some research on the optimization of cutting parameters and tool geometry angle in high-speed milling and high-speed turning graphite with large-diameter milling cutter (≠ 12 mm). The results show that: (1) in terms of tool wear, with the increase of cutting speed, the wear area decreases; with the increase of feed rate per tooth of milling cutter, the tool wear increases; with the increase of tool rake angle, the depth KT of crescent depression on the rake face decreases, but the width KB of the dimple on the rake face changes little; with the increase of the back angle, the wear of the back face decreases; the smaller the graphite grain size, the higher the tool life; and the tool life is roughly the same as the resistance The bending strength is proportional to the shore hardness. (2) In terms of cutting force, the cutting force of graphite material is only 10% of that of aluminum, copper and other ductile metals. When turning graphite electrode materials, the cutting force and its fluctuation amplitude increase with the increase of feed rate; the cutting force decreases with the increase of tool rake angle, and the change of cutting force is no longer obvious when the back angle increases to 60C: the higher the bending resistance of material, the greater the cutting force; brittle materials The influence of cutting speed on cutting force is generally negligible. (3) In the aspect of machined surface quality, the increase of cutting speed and cutting feed rate can reduce the surface quality; the increase of tool rake angle leads to the decrease of surface quality. Graphite rough machining aims at cutting off a large number of materials in a short time. Profiling milling or contour milling can be used. The advantages and disadvantages of rough machining process depend on the NC programming according to the function of tool surface contour curve, which makes it possible to carry out fast and simple milling along the contour line of the tool surface. In finishing machining, the influence of milling direction on machining accuracy and surface quality should be considered in the processing of bending angle. When milling along the curved surface, pull milling and drilling milling will occur, and the deformation of the tool will lead to the profile deviation of the workpiece. The best strategy of milling along the plane contour is to use the combination of up milling and plane contour milling. The main problem of prismatic surface machining is the fracture of the local corner of the die, so the direction of cutting force should be considered. At present, the process parameters commonly used in high-speed machining strategy of graphite electrode high-speed machining enterprises in China mainly rely on the experience of programmers and select according to the general principles, but there has not been theoretical and applied research on the programming strategy and process parameter optimization of special structural parts.