Mathematical Representation of Friction in Metal Forming Analysis
As recently stressed by Kalpakjian [1]. Schey [2] and many other authors [3-8] the development is an improved friction model is an important topic in metal farming analysis. In the present study a fresh friction approach is suggested. It connects the friction shear stress not only with the normal stress but also with the relative displacement between tool and workpiece and the relative surface increase. The model presented is based on the physical conception of the friction phenomenon as described by Schey [2.4″], Wanheim, [7] and Dautzenberg [8, 9]. Connections with the well known Coulomb model (T Fr = up) and the so called constant friction model [T Fr = m J F /✓3 and discussed. Theoretical findings are verified with experimental data from different tests. Although a few questions are still open, some progress in technical understanding of friction in forming tools could be achieved.
Metal Forming Analysis
There are a wide range of physical defects which occur during metal forming processes. These defects, which may occur on the surface or be internal, are undesirable not only because of the surface appearance, but because they may adversely affect the strength, formability and other manufacturing characteristics of the material. Some physical defects in metal forming processes such as rolling and forging, Defects in forging reduce its strength. Appreciable residual stresses and warping can occur on the quenching of steel forgings in heat treatment. They occur for a number of reasons including faults in original metal, incorrect die design, improper heating and lubrication. Defects of forged product include exterior cracking, interior cracking, laps, cold shuts, warping of the part, improperly formed sections and dead zones. In this project we will analysis the metal of forging and try to reduce metal defects in forging processes. Finite element analysis is used to predict residual stresses in forgings .The objective of this project is to obtain an optimal billet shape in the consideration of the metal flow deformation in closed die forging process. Finite element method in conjunction with optimization algorithm was used to analyze the effect of billet shape on forging load in axisymmetric closed for die forging process. ANSYS was used to simulate closed die forging process and then performing a series of optimization iteration in order to obtain the optimal shape of the billet based on forging load minimization. The material used is aluminum metal matrix composite (ALMgSi matrix with 10% SiC particles). The goal of the simulation and optimization process is to minimize the forging load and produce crack-free forgings. The optimal shape of the billet that gives minimum forging load was obtained after several optimization iterations. The approach used in this study could be extended to the optimization of more complicated forging product. Due to the advances in computer technology based finite element software, the forging load can be easily estimated which is iterative process in the old technique of prototype built up and destructive testing. In the present work consideration 3 critical design parameters with critical plastic strain limit as the state variable and keeping the forging load as the objective function and the billet shape is optimized for different diameter to height.
Traceability strategy for gear-pitch-measuring instruments: development and calibration of a multiball artifact
There is a strong demand to ensure the traceability of gear-measuring instruments (GMIs). We propose a multiball artifact (MBA) for the evaluation of pitch-measuring accuracy. The aim of the MBA is to transfer the minimum uncertainty from a calibrated value at the National Metrology Institute of Japan (NMIJ) to a measured value of GMIs at a shop floor. The MBA is composed of equally spaced high-accuracy balls around an axis. The pitch-measuring accuracy of GMIs is evaluated by measuring the angular pitch deviation of the balls instead of the angular pitch deviation of a gear. We calibrated the angular pitch deviation using a coordinate measuring instrument (CMM) at the NMIJ and adapting a multiple-orientation technique. We proposed a calibration strategy of the angular pitch deviation. The calibration value of the pitch deviation for the MBA at the NMIJ was obtained with a measurement uncertainty (U95) of 0.2 µm. We evaluated the pitch-measuring accuracy of a GMI using the calibrated MBA. Each value of U95 for the cumulative and single pitch deviations for the left and right flanks was less than or equal to 0.5 µm. The small uncertainty was transferred from the NMIJ to the GMI.