| In high speed cutting,the surface morphology of the machined material changes due to the change of cutting parameters,and the surface morphology has a certain influence on the service life of the parts.Therefore,it is of great significance to study the relationship between machined surface morphology and surface roughness and machining parameters,establish the relationship between cutting parameters and fatigue life based on Peterson model,and explore the influence rule of high-speed cutting parameters on fatigue life,in order to improve the surface morphology and then improve the fatigue life of materials.In this paper,taking Ti-6Al-4V of titanium alloy as the research object,two single-factor turning tests were carried out.The fatigue test was completed for the specimen in the second turning test.The roughness value of the machined surface of the two turning tests was measured,the surface morphology was observed and the fatigue fracture of the specimen in the high-cycle fatigue test was observed and studied.The main contents and conclusions of this paper are as follows:1.For the first turning experiment,observe and test the machined surface roughness and surface morphology after cutting,and explore the change rule of surface roughness and surface morphology of high-speed cutting Ti-6Al-4V.The results show that the roughness of the machined surface increases first and then decreases with the increase of cutting speed,but the change is not obvious.With the increase of feed,the roughness value of the machined surface increases gradually and the change is very obvious.With the increasing of cutting depth,the roughness value of the machined surface of Ti-6Al-4V titanium alloy has no obvious change rule.2.According to the second turning experiment,the influence law of feed change on the surface contour 3D morphology characteristic parameters was explored.The research shows that:the characteristic parameters representing the three-dimensional morphology of the surface contour increase with the increase of feed.When the feed is 0.1mm/r?0.2mm/r,the sensitivity of surface geometric parameters R_z and S_a to the change of feed is relatively low.At this time,the sensitivity changes slowly and it is suitable for machining high-precision parts.When the feed is 0.2mm/r?0.3mm/r,the sensitivity of surface geometric parameter S_a to feed change increases suddenly,which is not conducive to parts with high machining accuracy.3.Aiming at the high-cycle fatigue experiment,combined with the influence of feed change on the surface morphology during machining,the fatigue fracture was analyzed and the influence of cutting parameters on the fatigue life of titanium alloy Ti-6Al-4V was deeply explored by Peterson model.Research shows that the effective stress concentration factor K_f as comprehensive embody the surface stress concentration produced by geometrical parameters effect on fatigue performance of functions,along with the increase of feed,K_f also gradually increased,and the effective stress concentration factor K_f and assumes the inverse proportion relationship between fatigue life,the greater the effective stress concentration factor,the lower the fatigue life. |
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