Papers by Keyword: Lapping Uniformity

Abstract: In this paper, a novel lapping method based on regulating the position of carrier centroid is proposed to modify interfacial normal pressure uniformity. Eight special points are selected to represent carrier weight. This lapping process can be divided into initial stage, regulated stage and stable stage. The purpose of initial stage is calculating the position of carrier centroid according to the equivalent mass of eight points. The regulated stage is to decrease total thickness variation (TTV) by regulating the position of weight. Finally, the stable stage will keep uniformity of material removal rate (MRR) uniform at each point. A 3-inch and 400 μm thickness silicon wafer is lapped to demonstrate the feasibility of this method. We can find that TTV of this wafer decreases from initial stage 20 μm to 3 μm and remain constant. Therefore, the uniformity of MRR has been greatly improved by this novel lapping method.

Abstract: Researching the effect that certain parameters have on the lapping process is crucial to understanding the fundamental material removal mechanisms and implementing a procedure that most efficiently produces desired results. This study examines the lapping procedure for polycrystalline diamond compacts (PDCs). Tests were conducted using different sample carriers, PDC arrangements, and abrasive size distributions. Previous studies have focused on the material removal rate (MRR), which is of interest, but this study also examines the MRR uniformity within a group of PDCs lapped together. The goal of this research was to determine the optimal lapping conditions and PDC arrangement required to achieve the highest productivity. Results indicate that a hard specimen carrier is necessary to produce PDCs with uniform MRRs, and the number of PDC samples in a carrier can be increased with certain design constraints kept in mind.

Abstract: The lapping trace distribution on ball surface is one of the key factors during the lapping process, which can affect the sphericity of lapping. The Rotated Dual-Plates lapping mode (RDP lapping mode) can achieve better uniformity of lapping trace distribution on precision ball surface, which ensure the results of forming sphere by lapping. Combining with the basic principle of RDP lapping mode, as well as the analysis of the kinematics of the RDP lapping method, this paper puts forward a basic rule about the material removal at the contact point between the ball and the plate with the material removal rate equation of bearing steel, and the improvement of the sphericity which can be simulated, and is defined as the lapping uniformity according to basic rule equation. The influence caused by the lapping pressure and the speed of the plates are considered in the simulation, the surface of ball is triangle grid divided. The uniformity of lapping is evaluated at different speed ratio, and eventually a better curve of the speed ratio can be got, so the lapping uniformity during the RDP lapping mode can finally be accurately evaluated.

Abstract: The precision and efficiency of lapping for balls are determined by the lapping uniformity. One method of evaluating the ball lapping uniformity for different lapping mode is proposed, which is based on kinematics analysis under the assumption of pure rolling. Lapping experiments of V-groove lapping mode, dual rotating plates (DRP) lapping mode, and dual-rotating eccentric V-groove (DREVG) lapping mode are carried out on steel balls, and the lapping traces are observed. The prediction of the evaluating method is in accordance with the experimental results.

Abstract: To study the sphere-shaping mechanism under dual rotating plates (DRP) lapping mode for ceramic balls, the uniformity of lapping trace distribution is focused in this paper. Methods for simulation and evaluation of the lapping trace uniformity are proposed, and the effect of velocity parameters on the lapping uniformity of ball under DRP lapping mode is analyzed. It is found that the lapping uniformity is dependent not only on the variation range of spin angle θ, but also on the spin angle speed ωb and on the variation form of θ. The analysis results indicate that the effect of amplitude of the speed ratio function on the lapping uniformity is much greater than the effect of phase on that. When the ratio of the inner plate speed to the outer varies from 0 to2, the best lapping uniformity is obtained under the conditions demanded by this paper.

Abstract: A novel lapping mode is developed on the base of present eccentric v-grooves lapping mode for precise balls. The kinematics analysis shows that the ball spin axis can wiggle up to 180° under the developed mode, so the lapping trace will be dispersed onto the whole surface of the ball. The effect of offsetting and groove radius on the lapping uniformity in the developed eccentric v-grooves, the present eccentric v-grooves and the traditional v-grooves lapping mode are compared, and the advantage of the developed mode is that the impact offsetting is less while the groove radius has no impact.