Key Engineering Materials Vol. 693

Abstract: Through injection molding simulation software and examples of injection,This paper analyzes the causes of the weld line when injection molding products, the impact on the quality of products, analysis of the injection mold gate location selection problems and defects produced by principle, think weld line has a great influence on the quality of injection molding, on this basis, put forward in view of the weld line, the influence of the mold gate location selection method in the practical work of is: reasonable choose the location of the gate, to control the degree of weld line, as far as possible to reduce the number of the weld line, or make them produce not important position in the mold. Etc.

Abstract: The selection of geometric parameters of cryogenic tap has a direct effect on the reliability of tools and the precision of processed workpiece. Based on nonsubstitute Type-I Censoring Life Tests, a mathematical model in dynamic reliability of cryogenic tap is built, and the change of its reliability is explored. Combined with cutting tool life expansion equation, the effects of geometric parameters on wear life are presented. The results show that of the geometric parameters, rake angle taps in its effect on reliability with the increase in machining time and impact loading action, thus the quality of rake angle should be controlled directly or indirectly so as to reduce its influence on reliability of cutting tool, which can ultimately improve the reliability of cutting tool and the precision of processed workpiece. Meanwhile, the proposed method provides a theoretical basis for improvements of the reliability of tool system.

Abstract: With the development of China's manufacturing industry, the multi axis NC Machining Technology is rapidly popular. In the case of impeller shaft processing, this paper introduces the NC machining method and of three axial impeller based on Cimatron software, It is important practical significance and reference value to realize multi axis machining by the three axis CNC equipment.

Abstract: The process parameters affect the lapping efficiency and the surface quality of work pieces. The fixed abrasive pad of w3-5 diamond abrasive was used for lapping magnesium aluminate spinel wafers in orthogonal experiment. The affection of lapping pressure, plate speed and slurry type on material removal rate (MRR) and surface roughness Ra were investigated. Finally, the process parameters were optimized. The results showed that lapping efficiencies were higher and the surface quality was better on the conditions of Zhongjing slurry, lapping pressure 10.37Kpa and plate speed 100rpm.

Abstract: This paper performed a series of finite element method (FEM) simulation to investigate the influence of the tool wear on the cutting temperature in the diamond ultra-precision cutting of the aluminum alloy mirror. The two-dimensional FEM model including the diamond tool with the different average width of wear land on flank face was established. A series of ultra-precision cutting experiments using different cutting distance was performed. The tool wear was detected by scanning electron microscopy (SEM), and the cutting temperature was detected by infrared thermal imager. The comparison of the simulation investigations and the experimental investigations was done. The results revealed that the cutting temperature increases with an increase of the average width of wear land on flank face in the FEM simulation. And in the ultra-precision cutting experiments the diamond tool wear becomes severe as the cutting distance increases, meanwhile the severe tool wear results in the higher cutting temperature. Consequently the FEM simulations prove to be right.

Abstract: Slender shaft is of high slenderness ratio and bad rigidity. The factors, for example, cutting force, cutting heat, vibration and so on, which are produced in the processing, will affect directly the size precision of workpieces. In this research, slender shaft is 304 stainless steel bar, with length of 450mm and diameter of 10mm. In order to resolve the problem of slender shaft machining with CNC slant bed lathe not configured with the follow-rest, a self-made follow-rest was developed. With both ends clamped processing mode, it is possible to use the CNC lathe turning slender shaft. Moreover, better effect of turning of slender shaft can be attained if ultrasonic vibration cutting technology is involved. After turning process is completed, size accuracy is checked to evaluate the effect of self-made follow-rest and both ends clamped processing mode. In this study, the experimental results show that quality of the slender shaft processing has been significantly improved with the use of self-made follow-rest and both ends clamped processing mode, which has definite effects on solving the practical problems of processing.

Abstract: Polycrystalline Cubic Boron Nitride (PCBN) tool is suitable for cutting powder metallurgy valve seat, which has high hardness and contains hard particles. By hard dry cutting different materials of powder metallurgy valve seat, the results show that: tool life when cutting melting copper powder metallurgy valve seat is longer; breakage failure is the main failure forms of tool and wear mechanism contains hard spots scratches, adhesive wear, diffusion wear and oxidation wear.

Abstract: High-speed grinding experiment of titanium matrix composites is carried out with cubic boron nitride (CBN) superabrasive wheels in this work. The heat transfer into the titanium matrix composites (TMCs) is discussed based on theoretical analysis. A calculation method of thermal ratio passing into the workpiece is represented. Results obtained show that high-speed grinding of PTMCs using vitrified CBN wheel has a greater thermal ratio passing into the workpiece than using electroplated CBN wheel. Moreover, a linear relationship is established between e_s and d_s^1/4a_p^-3/4v_w^-1/2.

Abstract: This paper presents a study of the influence of cutting conditions (cutting velocity, feed, cutting depth and lubrication) on turning TC11 (Ti-6.5Al-3.5Mo-1.5Zr-0.3Si) titanium alloy. Taguchi methodology design was adopt for carrying out experiments. Turning process parameters such as cutting speed, feed rate and depth of cut were varied to study their effect on process responses such as cutting force (Ft), surface roughness (Ra) and temperature on cutting zones (T). Minimum quantity lubrication (MQL) technology was adopt to increase the lubricating and cooling effect. Meanwhile, CVD diamond coating was deposited on the cemented carbide insert to reduce its friction with workpiece and increase its wear resistance. From the analysis of orthogonal tests, depth of cut contributes the most for the main cutting force and cutting temperature, while feed rate had the most significant effect on surface roughness on the workpiece. MQL can reduce the cutting temperature at the cutting zones, especially for the uncoated cutting inserts whose temperature decreases by an average of 60~80°C. The cutting force, surface roughness and cutting temperature of CVD diamond coated inserts were all higher than those of uncoated tools, especially with MQL lubrication. Considering the cutting efficiency and cost, the optimal parameters in the turning process of TC11 for minimizing the cutting force, surface roughness and cutting temperature are obtained as Vc=115m/min, f=0.08mm, a_p=0.5mm under MQL lubricating with uncoated cemented carbide as the cutting tool.

Abstract: In this paper, ultra-precision cutting experiments were carried out with titanium alloy material Ti-6A1-4V by using single crystalline diamond tools. Experimental results show that the wear patterns of rake face of diamond tools are crater wear and groove wear, the wear patterns of flank face of diamond tools are uniform wear and groove wear, and the wear mechanisms of single crystalline diamond tool are chemical wear and mechanical wear. Graphitization and microcosmic cleavage of the diamond tools occur in the cutting process.