Key Engineering Materials Vols. 304-305

Abstract: It is of high importance to avoid scratches in lapping process. A Grain Size Sensitivity (GSS) model is put forward in this paper. The GSS is a relative parameter which defines the relative change of the depth of cutting, influenced by the change of the size of grain powders, by which it is possible to evaluate quantificationally the capability of lapping machines in avoiding scratches. It is useful for designing and using lapping machines. The simulating of lapping processes based on GSS model is carried out. The transferring of error is also discussed and a new structure of lapping plate with spring cells developed by the authors is introduced.

Abstract: Cesium Lithium Borate (CsLiB6O10 or CLBO) is the most effective non-linear crystal which generates ultraviolet harmonics of the Nd:YAG fundamental laser wavelength. In order to enhance the damage threshold, low CLBO surface roughness, by ultra-precision machining, is needed. Because the CLBO crystal has easy hydroscopic reaction and micro scratches in machining, ultra-precise machining of the CLBO crystal is a difficult technical problem. In this paper, the new lapping slurry and polishing slurry are introduced. And the deliquescence degree of CLBO is fallen to lowest. A new working technology is also adopted. After rough polishing, the concentration of ultra-precision polishing slurry is increased properly. So does the ultra-precision polishing speed, and the wiping speed is faster than the deliquescence speed. The CLBO crystal surface roughness can achieve 1nm and keep the surface quality well.

Abstract: To understand the mechanism involved in the lapping process of the silicon nitride balls, the wear mode is investigated in this paper. The abrasion tests were performed on a ball-plate wear test apparatus with different loads (0~2N/ball) and slurry concentrations (5%wt~30%wt W20 B4C3). The abraded surface is observed by optical telescope. A wear-mode map, which defines the regimes for two-body abrasion or three-body abrasion dominating in the micro-scale abrasion test, is plotted with two axes: load and concentration of abrasive. An empirical formula for the wear mode transition is adopted to calculate the transition point S*, which can then used to predict the wear mode in lapping process of silicon nitride ball.

Abstract: The theory and effect of gear-honing are wholly different between electroplated CBN hard honing wheel and epoxy resinoid soft honing wheel. In the paper, through deeply analyzing the mechanical character and engaging situation of both plated CBN hard honing wheel and gear, the bending deformation, contact distortion and cutting depth are calculated at engaging point. At last, the manufacturing technology combining conventional CBN electroplating and thermal diffusion in vacuum to produce gear-honing wheels for hardened tooth is introduced. These are important to improve the machining accuracy and finish of hardened gear tooth surface.

Abstract: Vibration disk has certain influence on the resonance frequency of ultrasonic honing vibration system when ultrasonic honing device is designed. The results of theoretical calculation are basically conformed to that of experiments, which have been investigated by means of experimental and theoretical calculation method. This study provides a basis for the development of ultrasonic honing device. Undergoing practice we can find that the efficiency ultrasonic honing system as above described can be extended and applied to production. The system is a typical non-conventional machining, but it can be applied not only to conventional honing machine , its technology effect as good as high precision machine tool , but also to developing and studying ultrasonic vibrating numerical controlling honing machine tool which will provide a new type, efficient, high quality low consumption, equipment for working precision hole.

Abstract: The removal of redundant layer of deposited metal of the micro coils is one difficult problem in the fabricating of micro-mechanical electromagnetic relay. In view of the machining efficiency and quality, the paper introduced lapping and polishing technology. The paper also analyzed the characteristic of lapping and polishing and introduced the appropriate abrasives. Then the main procedures were presented and the measuring result was given in the paper. The surface roughness of the coil could satisfy the next layer fabricate requirements of the micro-mechanical electromagnetic relay. At last the paper concluded the optimized lapping and polishing parameters.

Abstract: Based on the direction-parallel path planning method, this paper constructs a kinematics model and an inverse kinematics model for a robotic ultrasonic EDM polishing system, and it presents the arithmetic on joints’ rotating displacements and joints’ rotating speeds. A set of computerized solutions to the two models is developed for the robotic polishing system under the conditions of keeping feed speed Vf and machining angle λ at some constants on free-form surfaces. In this way, it puts forward an easy and efficient way for robot in free-form surfaces polishing.

Abstract: In this paper, a novel bipod parallel grinder with four controlled degrees of freedom is introduced. The moving platform of this 2-leg parallel grinder can always keep moving in horizontal plane by means of four-parallelogram mechanism (Π joints). The closed-form solutions of forward and inverse kinematics are derived.