Design study of the geometry of a punching/blanking tool

The cost of tooling in sheet metal industries contributes a considerable part to the overall cost of manufacturing a component. It is therefore imperative to keep down this cost by ensuring that the tool works for a long period in production without interruption. One way of achieving this objective is to reduce the stress on the tool during punching/blanking.\ud \ud This paper deals with the study of this problem by using the finite-element technique. 3-D finite-element models of various type of punching/blanking tools have been developed, these models enabling the analysis of the effects of variations in tool geometry on the punching/blanking force and on the deformation of the punch, a parameter highly relevant to the assessment of tool performance in terms of the accuracy of the manufactured components. The model caters also for variation in the characteristics of the tool material, in the sense that a highly wear-resistant tool is normally composed of carbide tips around its cutting profile. Computed results by FE models are checked against design standards by American Society of Manufacturing Engineers (SME). Some suggestions are offered as to how the efficiency of a punching/blanking tool can be improved

Remote sensing of D-region ionosphere using multimode tweeks

Lightning discharges radiate electromagnetic waves in a wide frequency range, with maximum energy in extremely low frequency/very low frequency band. A part of the radiated extremely low frequency/very low frequency wave energy is trapped in the Earth–ionosphere waveguide and travels thousands of kilometers in different modes with lower attenuation. Amplitude, frequency and phase of these waves are used to study the less explored D-region ionosphere at lower latitudes. Extremely low frequency/very low frequency observations are recorded continuously by automatic whistler detector setup installed at low-latitude Indian station Lucknow (Geom. lat. 17.6 ° N; long. 154.5 ° E). In total, 149 cases of tweeks having modes ranging from 3 to 6 have been recorded by automatic whistler detector during December 2010 and analyzed. Result shows that the propagation distance in the Earth–ionosphere waveguide lies between 1.1 and 9.4 Mm. The electron density in the lower D-region varies between 25 and 150 cm - 3 . The upper boundary of the waveguide varies between 80 and 95 km. The reported results are in good agreement with the earlier measurements at different latitudes and longitudes

A process model for air bending

A so called `three-section¿ model for air bending is presented. It is assumed that a state of plane strain exists and that Bernoulli's law is valid. The material behaviour is described with Swift's equation, and the change of Young's modulus under deformation is addressed. As compared with other models, the model described in the paper is capable of generating information such as required punch displacement and the unfolded blank size, very accurately. With in-process measurement of the spring-back angle, the punch displacement can be calculated even more accurately

On the Performance of Pivoted Curved Slider Bearings: Rabinowitsch Fluid Model

The present theoretical analysis is to investigate the effect of nonNewtonian Pseudoplastic & Dilatant lubricants (lubricant blended with viscosity index improver)–Rabinowitsch fluid model on the dynamic stiffness and damping characteristics of pivoted curved slider bearings. The modified Reynolds equation has been obtained for steady and damping states of the bearing. To analyze the steady state characteristics and dynamic characteristics, small perturbation theory has been adopted. The results for the steady state bearing performance characteristics (steady state film pressure, load carrying capacity and centre of pressure) as well as dynamic stiffness and damping characteristics have been calculated numerically for various values of viscosity index improver using Mathematical 7.0 and it is concluded that these characteristics vary significantly with the non-Newtonian behavior of the fluid consistent with the real nature of the problem

Preface

The multiple facets of modern sheet metal manufacturing techniques are applied throughout a wide spectrum of economy, ranging from the automotive industry and machine manufacturing to electrical engineering and electronics. This wide range of applications means that sheet metal manufacturers produce parts from a few grams up to 1000 kg and more — from electro-technical parts up to components in automotive industry — as well as batch sizes ranging from just a few pieces to mass production. Worldwide, around 12,300 companies employing 600,000 workers produce sheet metal goods worth over 732 billion US dollars. These are impressive numbers for sheet metal manufacturing, to which forming processes are central, but also for cutting and joining technologies with their increasing importance. All of these processes have developed dynamically in the recent past, and this trend will no doubt continue

Synthesis, antileishmanial activity and QSAR studies of 2-chloro- N -arylacetamides

ABSTRACT We describe herein the synthesis and evaluation of the antileishmanial activity against promastigote forms of Leishmania amazonensis and cytotoxicity to murine macrophages of a series of 2-chloro-N-arylacetamide derivatives. All compounds were active, except one (compound 3). Compound 5 presented the most promising results, showing good antileishmanial activity (CI50=5.39±0.67 µM) and moderate selectivity (SI=6.36), indicating that further development of this class is worthwhile. Preliminary QSAR studies, although not predictive, furnished some insights on the importance of electronic character of aryl substituent to biological activity, as well as an indirect influence of hydrophobicity on activity