Bing Guo

Deformation analysis of micro/nano indentation and diamond grinding on optical glasses

The previous research of precision grinding optical glasses with electrolytic in process dressing (ELID) technology mainly concentrated on the action of ELID and machining parameters when grinding, which aim at generating very “smoothed” surfaces and reducing the subsurface damage. However, when grinding spectrosil 2000 and BK7 glass assisted with ELID technology, a deeply comparative study on material removal mechanism and the wheel wear behaviors have not been given yet. In this paper, the micro/nano indentation technique is initially applied for investigating the mechanical properties of optical glasses, whose results are then refereed to evaluate the machinability. In single grit diamond scratching on glasses, the scratching traces display four kinds of scratch characteristics according to different material removal modes. In normal grinding experiments, the result shows BK7 glass has a better machinability than that of spectrosil 2000, corresponding to what the micro/nano indentation vent revealed. Under the same grinding depth parameters, the smaller amplitude of acoustic emission (AE) raw signals, grinding force and grinding force ratio correspond to a better surface quality. While for these two kinds of glasses, with the increasing of grinding depth, the variation trends of the surface roughness, the force ratio, and the AE raw signals are contrary, which should be attributed to different material removal modes. Moreover, the SEM micrographs of used wheels surface indicate that diamond grains on the wheel surface after grinding BK7 glass are worn more severely than that of spectrosil 2000. The proposed research analyzes what happened in the grinding process with different material removal patterns, which can provide a basis for producing high-quality optical glasses and comprehensively evaluate the surface and subsurface integrity of optical glasses.

Investigation of forming process for micro‐socket connecters

Abstract The development of micro‐electro‐mechanical systems (MEMS) and micro system technology (MST) has improved the development of micro manufacture technologies such as microforming. In this investigation, the micro‐socket connecter was selected as the forming target since it is widely used in micro electronic industries. The forming scheme of micro‐socket connecters was investigated from the viewpoint of three procedures: blanking the contour and locating hole, blanking the socket and the bending process. The forming experiments were performed with T2 copper foil of 0·08u2005mm thickness. The effects of punch speed and grain size on the maximum punch force, bending force, cross‐sectional quality and springback angle were studied in detail. The results show that the maximum punch force decreases with the increase in punch speed and grain size. However, the maximum punch force increases slightly with the increase in grain size in the blanking socket procedure. The smoothly sheared area ratio becomes smaller with the increase in punch speed and grain size. The punch speed has a negative effect and grain size has a positive effect on springback angle. Analysis was carried out by considering the polycrystalline structure of the metallic material.

Analysis of blanking vibration with consideration of the break-through state

Abstract In this paper a method for analyzing blanking vibration is introduced which uses the unloading slope of the blanking force versus stroke curve. A theoretical simple vibration model for analyzing the effects of the unloading slope and the system stiffness on the blanking vibration and the best relationship between them is given also. Many non-linear mechanical factors such as the die structure, the plastic deformation of parts, damping and the gap in joints are considered in the analysis. The results of the analysis will be very useful for die design, machine selection and the development of new methods for decreasing the noise of equipment.