Modeling of cutting forces in five-axis milling of sculptured surfaces directly from a CAM tool path

The present work is motivated by the fact that for predicting cutting forces, which arise under various cutting conditions, workpiece-tool pairs and machining depths, the numerical methods are slower and less efficient than the analytical methods. In addition, recent developments in Computer Assisted Machining (CAM) techniques have enabled analytical methods to be applied even with a complex workpiece geometry. The present paper presents a practical and powerful analytical method which is based on the use of the toolpath file as the main information source for the machined surface. This method takes into account tool position and orientation in a five-axis milling process with tool ball-end modeled as a sphere called bull-nose. Also assumptions are made to get a good approximation in the calculation of global and local cutting forces, in the aim of developing an analytical model able to predict the cutting forces for five-axis milling process, easy to apply for any practical case.

Geoheritage of East Kazakhstan

East Kazakhstan is physiographically a diverse region of north-central Asia encompassing a broad array of geomorphic zones and geo-ecosystems from the western open steppes to the interior arid basins with wind-sculptured surfaces of the surrounding rocky highlands aligned by the high alpine mountain ranges. The complex regional geological history gave rise to a mosaic of impressive landforms located within a relatively small area. The extraordinary relief with many unique geo-sites was generated by dynamic processes associated with the late Cainozoic orogenesis in conjunction with the past climatic variations. The cyclicity of bedrock weathering and mass sediment transfer are manifested by Mesozoic fossiliferous formations, large sand dune fields, and loess-palaeosol-cryogenic series providing archives of the Quaternary evolution. Pleistocene glaciations followed by cataclysmic floods from the released ice-dammed lakes during the recessional glacier stages have produced an exceptional imprint in the mountain areas. Many archaeological localities and historic monuments, some being a part of the UNESCO World Natural and Cultural Heritage, are associated with the most prominent topographic places. Geo-tourism focusing on the most exquisite landscapes and spectacular geological settings is the new trend in the country with still minor activities that take advantage of the region’s supreme geoheritage potential. The great geo-diversity accentuates the touristic value of this still marginally explored geographic area. Reconnaissance, documentation, and publicity of the most unique geo-sites and geo-parks provide an impetus for their registration in the national and international nature heritage protection programs under proper geo-environmental conservation policies.

Empirical Models for Surface Roughness and Topography in 5-Axis Milling Based on Analysis of Lead Angle and Curvature Radius of Sculptured Surfaces

The orientation of the tool axis and the variable curvature of the machined profile of a sculptured surface have a significant impact on the roughness and topography of the surface in the process of 5-axis milling by means of a toroidal milling cutter. The selection of the orientation of the toroidal milling cutter axis relative to the radius of curvature of the machined surface profile is very important as it can provide a better surface quality and an even distribution of roughness parameters. In this paper, an attempt to carry out model tests to obtain mathematical relationships was made. These relationships were to determine the impact of the tool axis orientation and the variable curvature radius of the machined profile on the surface roughness and its topography in the 5-axis milling process of sculptured surfaces. The tests were conducted on an example of a turbine blade made of Inconel 718 alloy. A measurable effect of the work undertaken was the development of model relationships that can be applied in specialized modules of CAM (Computer Aided Manufacturing) systems supporting the programming of 5-axis machining of sculptured surfaces. The models developed will also make it possible to obtain an evenly distributed roughness on the machined sculptured surface, especially on the surface of the turbine blades of the Inconel 718 alloy, as indicated by the results of the tests carried out.

Geometric Modeling of Compound NURBS Surfaces

The design of sculptured surfaces occupies an essential area in the field of modern industrial, aerospace, and medical applications. The challenge is to design products that have complex features efficiently with great flexibility of editing in certain regions without affecting other regions, which the designer has no intent to modify. In this paper, we propose a surface design method based on compound NURBS surface to model automotive parts with 400 control points. First, a Non-Uniform B-Spline basis function is derived with a cubic degree and 20 control points. This method is utilized to design car posterior door, car hood, and rear car door as case studies.

An Improved Measurement Uncertainty Calculation Method of Profile Error for Sculptured Surfaces

The current researches mainly adopt “Guide to the expression of uncertainty in measurement (GUM)” to calculate the profile error. However, GUM can only be applied in the linear models. The standard GUM is not appropriate to calculate the uncertainty of profile error because the mathematical model of profile error is strongly non-linear. An improved second-order GUM method (GUMM) is proposed to calculate the uncertainty. At the same time, the uncertainties in different coordinate axes directions are calculated as the measuring points uncertainties. In addition, the correlations between variables could not be ignored while calculating the uncertainty. A k-factor conversion method is proposed to calculate the converge factor due to the unknown and asymmetrical distribution of the output quantity. Subsequently, the adaptive Monte Carlo method (AMCM) is used to evaluate whether the second-order GUMM is better. Two practical examples are listed and the conclusion is drawn by comparing and discussing the second-order GUMM and AMCM. The results show that the difference between the improved second-order GUM and the AMCM is smaller than the difference between the standard GUM and the AMCM. The improved second-order GUMM is more precise in consideration of the nonlinear mathematical model of profile error.