Computer simulation of the rotary cutting edges with helical teeth on the complex surfaces
this paper researched the forming theory of the cutting tools with helical teeth and complex surfaces. Deduced the nonlinear equations of the movement of NC system to generate such tools, presented the way to find the solution of the equations, calculated the cross section graphics of the teeth profile and computer simulation of NC machining.
A manufacturing model of carbide-tipped spherical milling cutters
Abstract The paper presents a manufacturing model for use in grinding the front-end surfaces of a carbide-tipped spherical milling cutter. The concepts of radial equidistant lines and oblique equidistant surfaces are presented. Based upon these concepts, a model of the cutting edge of a spherical milling cutter is derived by solution for the intersection of the spherical front-end surface of the cutter and the equation of a sphere. A special mechanism model is also presented for grinding the rear cutting-edge surface of the cutter. To ensure that the mechanism model is valid, the cutting-edge curve of the cutter is also on the rear cutting-edge surface. The associated geometric and manufacturing parameters are further optimized to ensure that the best quality of the carbide-tipped spherical milling cutter can be achieved. The mechanism is also used to study the manufacturability of spherical milling cutters for slightly varying specifications. A numerical example is presented to illustrate the effectiveness of the proposed modelling procedure for producing carbide-tipped spherical milling cutters. Numerical results indicate that the proposed manufacturing model and grinding procedure are capable of producing a family of carbide-tipped spherical milling cutters with an accuracy up to the user-provided specific tolerance. Some major contributions of the proposed approach are summarized in the conclusions.
Ultrathin Wafer Pre-Assembly and Assembly Process Technologies: A Review
Ultrathin silicon wafer technology is reviewed in terms of the semiconductor applications, critical challenges, and wafer pre-assembly and assembly process technologies and their underlying mechanisms. Mechanical backgrinding has been the standard process for wafer thinning in the semiconductor industry owing to its low cost and productivity. As the thickness requirement of wafers is reduced to below 100 μm, many challenges are being faced due to wafer/die bow, mechanical strength, wafer handling, total thickness variation (TTV), dicing, and packaging assembly. Various ultrathin wafer processing and assembly technologies have been developed to address these challenges. These include wafer carrier systems to handle ultrathin wafers; backgrinding subsurface damage and surface roughness reduction, and post-grinding treatment to increase wafer/die strength; improved wafer carrier flatness and backgrinding auto-TTV control to improve TTV; wafer dicing technologies to reduce die sidewall damage to increase die strength; and assembly methods for die pick-up, die transfer, die attachment, and wire bonding. Where applicable, current process issues and limitations, and future work needed are highlighted.