Materials Science Forum Vols. 626-627

Abstract: A method was presented for calculating the temperature distribution of primary shear zone in orthogonal high speed cutting based on the non-uniform volume moving heat source. The temperature distribution of primary shear zone in orthogonal high speed cutting was calculated by the dynamic plastic constitutive relationship and the distribution of strain and strain rate of primary shear zone. The results show that the temperature distribution of primary shear zone is uneven, from the original plane to the cutoff plane, the cutting temperature increases continuously. In the middle of primary shear zone, the change of cutting temperature is larger, at the position near to original plant and cutoff plane, the change of cutting temperature is smaller. The cutting temperature increases with the increase of cutting speed and cutting depth, but decreases with the increase of rake angle. The comparison with existing method shows that the method presented in this paper is not only available, but also simple, convenient and more accord with the fact of orthogonal high speed cutting.

Abstract: This paper presents the research on calibration for a 6-component huge force sensor. 6-component huge force sensor is used to measure the loading forces Fx, Fy, Fz and moments Mx, My, Mz. Static calibration equipment is studied. In order to express the relationship between input force signal and output electric signal when the sensor is used, a coupling matrix is needed. In this paper, a method for establishing the coupling matrix is developed. The matrix is used to calculate the input signal when sensor works in the simulation application, and the result shows it serves the sensor well.

Abstract: A new approach is presented to optimize the tool life of solid carbide end mill in high-speed milling of 7050-T7451 aeronautical aluminum alloy. In view of this, the multi-linear regression model for tool life has been developed in terms of cutting speed and feed per tooth by means of central composite design of experiment and least-square techniques. Variance analyses were applied to check the adequacy of the predictive model and the significances of the independent parameters. Response contours of tool life and metal removal rates were generated by using response surface methodology (RSM). The analysis results show that it is possible to select an optimum combination of cutting speed and feed per tooth that improves metal removal rate without any sacrifice in tool life.

Abstract: Complex surface mold has been widely used in various industries, and high efficiency and high quality can been achieved through high-speed CNC milling processing. Surface roughness including transverse and longitudinal roughness is an important criterion for mold quality. A high-speed milling experiment was performed in mold steel P20 using cemented carbide ball-end mill to investigate the surface roughness. The effects of process parameters on roughness including spindle speed, feed per tooth and radial cutting depth were examined, and an analysis on the mechanism for two kinds of roughness of different tool paths was finished. The experimental results show that the longitudinal roughness improve obviously while the spindle speed and the feed per tooth increase on the high-speed conditions, and the transverse roughness increase significantly when the radial cutting depth increases. And for a smaller roughness value, the tool path should be selected along the direction in which the curvature changes evidently.

Abstract: High-speed machining thoroughly hardened tool steels has emerged as a competitive finishing technology for making dies and molds. The objective of this paper is to develop an optimization method for the better (i. e., lower value) surface roughness in terms of cutting parameters when high-speed milling hardened H13 steel. The cutting parameters to be considered were cutting speed, feed per tooth, radial depth of cut, and axial depth of cut, respectively. A series of high-speed milling experiments of hardened H13 steel using PVD coated carbide inserts without any cutting fluids were performed to measure the surface roughness data. Taguchi orthogonal arrays, signal-to-noise (S/N) ratio, and analysis of variance (ANOVA) were used to evaluate the effects of cutting parameters on surface roughness and to find the optimal factor/level combination for the better surface roughness. The investigations of this study would be used for design optimization of cutting parameters to obtain the better surface roughness.

Abstract: Through analysis of the thermal errors affected NC machine tool, a new prediction model based on BP neural networks is presented, and ant colony algorithm is applied to train the weights of neural network model. Finally, thermal error compensation experiment is implemented, and the thermal error is reduced from 35μm to 6μm. The result shows that the local minimum problem of BP neural network is overcome, and the model accuracy is improved.

Abstract: This paper analyses the tire building hub mechanism, and the law in the course of working is studied. In accordance with principles of variable topology, the characteristics of the topology of the tire building hub is researched, and kinematics simulation analysis and verification are carried out. Based on the parallel mechanism, the new hubs are given, the types of the parallel mechanism are enumerated, which can achieve trajectory of the hub, and the folding way and controlling method of the tire building hub are ameliorated.

Abstract: Polishing is one of the important methods in manufacturing of Si wafers and in thinning of completed device wafer. This study will report the evaluation on abrasion of wafer according to processing time; machining speed and pressure which have major influence on the abrasion of Si wafer polishing, for this, this study design the head unit and analysis head unit. After that, apply to experiment. It is possible to evaluation of wafer abrasion by load cell and infrared temperature sensor. The evaluation of abrasion according to processing condition is selected to use result data that measure a pressure, machining speed, and the processing time. This result is appeared by abrasion in machining condition. Through that, the study cans evaluation a wafer abrasion in machining. It is important to obtain mirror-like wafer surface.

Abstract: Engineering ceramics are hard and brittle materials, that is very easy to crack when grinding, and processing mechanism is rather complex than that of metallic materials. One kind of AE signal based grinding contact detection and feeding control method for ceramic material processing is presented in this paper based on ceramic grinding mechanism study. Through a large number of experimental data analyzing, the relationship between grinding touch and the feature of AE signals is obtained, and the automatic and intelligent grinding process can be realized by grinding contact signal driving grinding numeral program. Application results indicate this method can prove grinding efficiency and process quality.

Abstract: In the grinding process, grinding fluid is delivered for the purposes of chip flushing, cooling, lubrication and chemical protection of work surface. Due to high speed rotating grinding wheel, the boundary layer of air around the grinding wheel restricts most of the grinding fluid away from the grinding zone. Hence, conventional method of delivering grinding fluid that flood delivery is not believed to fully penetrate this boundary layer and, thus, the majority of the grinding fluid is deflected away from the grinding zone. The flood grinding typically delivers large volumes of grinding fluid was ineffective, especially under high speed grinding conditions. In the paper, a theoretical model is presented for flow of grinding fluid through the grinding zone. The model shows that the flow rate through the contact zone between the wheel and the work surface depends on wheel porosity and wheel speed as well as depends on nozzle volumetric flow rate and fluid jet velocity. Furthermore, the model was tested by a surface grinding machine in order to correlate between experiment and theory. Consequently, the effective flow-rate model was found to give a good description of the experimental results and the model can well forecast the effective flow-rate in flood delivery grinding.