Polygonal extrusion

A sweeping operation called polygonal extrusion is defined to improve the modeling power of CSG-based modeling. It is assumed that a 2D cross-sectional polygon (sweeping polygon) moves in space while its containing plane is kept orthogonal to the tangent direction of the trajectory curve, a planar polygonal chain having no self-intersections. The objective of the paper is to compute the boundary of the swept volume of the sweeping polygon as a set of polygons (or triangles). The most significant challenge to accomplishing this objective is the problem of trimming the swept volume. To solve the trimming problem, 2D-curve offsetting methods are employed. Two algorithms are presented for polygonal extrusion that are based on different offsetting methods, the Voronoi diagram and PWID offset. The proposed algorithms have been implemented and tested with various examples. Published online: 28 January 2003     

大中型连杆锻件的切边、冲孔、校正工艺

在分析大中型连杆类锻件生产难点的基础上，提出了通过优化锻造工艺方案，设计了切边冲孔校正复合模。提高了带大孔的连杆类锻件的产品质量和生产效率。     

基于解析法的裁剪PDE曲面的生成技术

为解决基于偏微分方程的曲面裁剪问题,研究一种广泛应用于偏微分方程曲面的裁剪方法.首先介绍基于偏微分方程的曲面生成方法,其次由参数域内的曲线在曲面上的投影,得到所求裁剪曲面的边界,然后利用解析法求得裁剪后的PDE曲面,最后列举一系列的实例来说明该裁剪方法的应用并且专门研究多个裁剪区域的问题.     

QUANTITATIVE PREDICTION FOR SPRINGBACK OF UNLOADING AND TRIMMING IN SHEET METAL STAMPING FORMING

Based on the elastic-plastic large deformation finite element formulation as well as the shell element combined discrete Kirchhoff theoretical plate element (DKT) with membrane square element, deep-drawing bending springback of typical U-pattern is studied. At the same time the springback values of the drawing of patterns' unloading and trimming about the satellite aerial reflecting surface are predicted and also compared with those of the practical punch. Above two springbacks all obtain satisfactory results, which provide a kind of effective quantitative pre-prediction of springback for the practical engineers.     

Comparison of surface roughness quality obtained by high speed CNC trimming and high speed robotic trimming for CFRP laminate

This paper proposes an experimental approach for evaluating the surface roughness of the CFRP parts produced by high speed CNC trimming and high speed robotic trimming under various cutting conditions. A comparison is made between the surface roughnesses obtained by the two processes. The results obtained show that, the measured profiles obtained from high speed robotic trimming are dominated by a large trajectory deviation, as compared to machine tool trimming results. After the trajectory deviation effect is discounted, the results show that for the +45° ply orientation, the surface quality obtained through high speed robotic trimming is similar to what is obtained with the CNC machine. Furthermore, a significant relationship was observed between the surface quality and the ply orientation, whatever the machining process and the cutting conditions employed. The −45° ply orientation represents the worst case in terms of surface roughness, whatever the machining process. It is 4 times higher compared with that of +45° ply orientations,The results also show that the effect of cutting conditions on surface quality is significant for both machining processes tested.     

Surface profile texture characterization of trimmed laminated composite in the stacking sequence direction

The surface texture characterization of laminate composites is complex due to its heterogeneous structure and to the different stratified surface properties. Profile roughness parameters are highly impacted by those different layer properties, and their distributions are relatively spread out. A new filtering technique is proposed to improve the surface roughness parameter efficiency. To present issues from current filtering methods and to highlight this new approach, profile surface roughness taken from trimmed carbon fibre reinforced plastics samples are inspected in the composite stacking sequence using a contact profilometer. For each measurement, several roughness parameters are calculated. The efficiency of different filtering techniques is investigated through the roughness parameters distribution, calculated for up- and down-milling and for different tool wear. The new proposed technique, based on the separate characterization of plateaus and large deep valleys of the composite surface profiles, is found to be particularly efficient on the down-milling face.     

滤清器外壳一次成型复合模设计

本文主要对滤清器外壳成型方案进行分析和对比，介绍了在液压机上实现一次成型的复合模结构及工作过程，提高了生产效率，降低了废品率，提高了产品质量。     

Robust uniform triangulation algorithm for computer aided design

This paper presents a new robust uniform triangulation algorithm that can be used in CAD/CAM systems to generate and visualize geometry of 3D models. Typically, in CAD/CAM systems 3D geometry consists of 3D surfaces presented by the parametric equations (e.g. surface of revolution, NURBS surfaces) which are defined on a two dimensional domain. Conventional triangulation algorithms (e.g. ear clipping, Voronoi-Delaunay triangulation) do not provide desired quality and high level of accuracy (challenging tasks) for 3D geometry. The approach developed in this paper combines lattice tessellation and conventional triangulation techniques and allows CAD/CAM systems to obtain the required surface quality and accuracy. The algorithm uses a Cartesian lattice to divide the parametric domain into adjacent rectangular cells. These cells are used to generate polygons that are further triangulated to obtain accurate surface representation. The algorithm allows users to control the triangle distribution intensity by adjusting the lattice density. Once triangulated, the 3D model can be used not only for rendering but also in various manufacturing and design applications. The approach presented in this paper can be used to triangulate any parametric surface given in S(u,v) form, e.g. NURBS surfaces, surfaces of revolution, and produces good quality triangulation which can be used in CAD/CAM and computer graphics applications.     

吹氩站多功能精炼技术开发

二炼钢厂吹氩站改造后。钢水吹氩精炼更加能够满足实际生产需要。经过1年多的开发，吹氩站具有以下多种功能：钢包CAS吹氩、微调钢水中[Si]、[Mn]、[Ti]、[Nb]、微调钢水温度、喂铝线微调[Als]、喂碳线微调[C]、出钢前试气提高钢包底吹氩成功率，节约了生产成本缩减工序时间。     

数控化改造外圆磨床砂轮成形修整的应用

介绍了基于国产经济型开通数控系统改造的数控外圆磨床MKA1320/H的方法,针对数控外圆磨床复杂曲面砂轮的成形修整问题进行研究,通过开通数控开放式编程环境,完成了砂轮成形修整的数控编程,最后给出了完整程序。