| SKD11 is a kind of cold work die steel which is widely used domestically, as well as internationally. Subjected to high impact load and fatigue stress, so high requirements are put forward on surface integrity, fatigue performance and friction and wear properties, etc. Multi-axis CNC machining is an effective way widely used in aviation, aerospace, mold and other field of manufacturing. Therefore, it is theoretically and practically significant to investigate the influence of multi-axis machining process on SKD11 steel surface integrity, and fatigue performance and friction and wear properties.The easy-failure areas of typical parts stamping die are predicted by means of through the finite element simulation. The reliability of the simulation is verified by die processing and stamping test. The change of the roughness of the working surface of the die is tested, and the failure mechanisms of the die are studied.Multi-axis ball end milling of SKD11 steel single factor cutting experiments are conducted to study the influence of tool paths, cutting speed, radial depth of cut and feed per tooth on machined surface roughness, residual stress and microhardness .SKD11 steel three-point bending fatigue tests are conducted based on multi-axis ball end milling experiment. SKD11 steel samples fatigue lives under different processing parameters are obtained. Influence of multi-axis milling parameters on SKD11 steel fatigue lives were researched. And results show that tool paths have an important effect on fatigue performance. On one hand, the sample has a longer fatigue life if tool paths are parallel to tensile force direction. On the other hand, it is bad for fatigue performance if the two directions are perpendicular. Influence of each parameter on fatigue performance is not the same when the tool paths are different.Therefore, the machining methods for high fatigue life are put forward based on the test result.According to configuration of ball-on-dish reciprocate friction tests, friction coefficient and the wear quantity on ball end milled surface with different milling parameters are studied. And results show that the wear quantity is smaller relatively if the tool path is perpendicular to the direction of friction while the wear quantity is the biggest if the angle between tool path and the direction of friction is 45°. Influence of each parameter on friction coefficient is not the same when the tool paths are different. |
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