Effects of surface splicing characteristics of the hardened steel mold on the machined surface topography

Abstract

The car cover mold has characteristics of large structure size, complicated surface shape, dimensional precision, and high surface precision. The milling process of the splicing transition zone having different hardness can easily produce load mutation, which has an impact on the tool in the form of vibration. This vibration affects the surface topography of the splicing transition zone. In this article, we propose the surface motion model for ball-end milling cutter with impact vibration and the surface topography prediction model for splicing transition zone which is established based on the Non-Uniform Rational B-Splines (NURBS) surface control point reconstruction. Then, the effects of surface splicing characteristics (different hardness, over-seam scale, etc.) and processing parameters on the surface topography and on the residual height have been analyzed. Finally, based on the hardened steel surface splicing milling experiment, the accuracy of the surface topography model in which vibration impact has been incorporated is verified. At the same time, the corresponding roughness value and fractal dimension are calculated on the basis of two-dimensional contour graph under different splicing characteristics. The results show that the non-linear characteristics of the surface topography of the hardened steel surface are significant, and the best processing parameters can be obtained under different splicing characteristics.