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41.
An axial-feed mirror finish grinding of hard and brittle materials is proposed by controlling grain protrusion parameters. In this grinding, the grinding wheel feed is along the wheel axial direction rather than in the traditional wheel cutting direction. The objective is to understand how micron-scale grain protrusion parameters influence ductile-mode grinding and ultimately to realize efficient mirror finish grinding using a coarse diamond grinding wheel. In this study, the grain tip truncation (GT-truncation) was performed after dressing to improve grain protrusion topography. First, a formation model of axial-feed ground surface was constructed to analyze the effect of grain protrusion parameters and grinding parameters on the critical cutting depth transferred from brittle-mode removal to ductile-mode removal; then GC dressing and GT-truncation of #180 diamond grinding wheel were experimentally performed to investigate surface roughness and ductile-mode grinding behavior with reference to grinding parameters and grain protrusion parameters; finally, a truncated coarser #60 diamond grinding wheel was employed for mirror finish grinding to observe active grain number and grain protrusion angle. Theoretical analysis shows that this ductile-mode grinding is dominated by active grain number, active grain protrusion angle, wheel rotating speed and axial-feed speed, but it does not depend on the depth of cut assumed to be less than the grain protrusion height. Experimental results indicate that the GT-truncation may increase active grain number and grain protrusion angle for ductile-mode grinding when the axial-feed speed decreases to some extent. Moreover, the micro tip radius of diamond grain also influences the ground surface. It is confirmed that by increasing active grain number and grain protrusion angle synchronously, a truncated #60 diamond grinding wheel can be applied for efficient mirror finish grinding of the SiC ceramic plate at the axial-feed speed of 50 mm/min and the tool path interval of 0.1 mm. 相似文献
42.
Experimental study on ultrasonic elliptical vibration cutting of hardened steel using PCD tools 总被引:1,自引:0,他引:1
Diamond tools cannot usually be applied for machining hardened steels while applying conventional cutting technique. As an alternative, ultrasonic elliptical vibration cutting (UEVC) technique was successfully applied for obtaining mirror surface on such steels using single crystal diamond (SCD) tools. In order to reduce production cost without compromising mirror surface quality, polycrystalline diamond (PCD) tools may be tested against highly expensive SCD tools. However, study on machining of hardened steel using PCD tools applying the UEVC technique has not yet been reported. The current research presents an experimental study on UEVC of hardened stainless steel (a typical Stavax, hardness 49 HRC) using the PCD tools. Face turning experiments were carried out to investigate the effects of three machining parameters: nominal depth of cut, feed rate, and nominal cutting speed on output performances such as cutting force, tool flank wear, surface roughness, and chip formation. Experimental results show that nominal cutting speed has very strong influence on the output performances, compared to the other two parameters. The surface roughness improves with a decrease in cutting speed. A mirror-like surface of approximately 804 mm2 with a roughness value Ra of 11 nm was achieved at a lower cutting speed. Theoretical explanations have been given to support the results drawn from the UEVC experiments. It can be concluded that, while applying the UEVC technique, the inexpensive PCD tools instead of the SCD tools can be effectively applied to obtain optical surface for producing precise molds from the hardened steel. 相似文献
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Mehmet Karaçalı Sait Bulut Muhsin Konuk Kemal Solak 《International Journal of Food Properties》2013,16(5):1007-1017
The seasonal variations of fatty acids compositions in the muscle, liver, and ovarian tissues of mirror carp (Cyprinus carpio) living in Örenler Dam Lake were determined by using gas chromatography. The results obtained were subjected to statistical analyses by employing SPSS software and p < 0.05 was accepted as significant value. In the statistical analyses, multiple comparisons tests were performed. The results showed that monounsaturated fatty acids levels were found to be higher than that of polyunsaturated fatty acids and saturated fatty acids in all seasons. Palmitic and stearic acid levels were the highest in ovaries (19.95% in winter and 7.79% in summer, respectively). Oleic and palmitoleic levels were at the highest levels in liver tissues (34.53% in summer and 18.37% in winter, respectively). Docosahexaenoic (C22:6ω3, DHA), eicosapentaenoic (C20:5ω3, EPA), eicosatrienoic acid, and arachidonic (C20:4ω6, AA) levels were at the highest level as 17.27, 2.54, and 8.41% in ovaries in the winter and 6.37% in muscle tissues in the spring, respectively. ω3/ω6 ratios were 0.62–0.98 in muscle, 1.54–2.82 in the liver, and 2.82–3.89 in the ovaries. From the point of total fatty acid variations, the highest variations were observed as follows: muscle in spring (26.73%), liver in winter (33.85%), and ovaries in winter 36.38%. 相似文献
45.
Ductile mode machining of brittle materials such as ceramics is recognized as an emerging technology with important applications. Ductile machining is possible if the depth of cut is less than the critical depth of cut of the machined material. By using a new device for dressing a resin-bonded diamond wheel and an improved coolant system proposed here, ductile mode grinding of silicon and glass was achieved using an inexpensive, conventional surface-grinding machine. The low-cost dressing device also ensured minimum disruption to the grinding operation and a higher level of safety. A flooding supply of coolant at the grinding zone provided better cooling performance and lubrication. A relationship appeared to exist between the surface finish and the lightness values of ground silicon surfaces. 相似文献
46.
我国塑料成型模具用材料的进展 总被引:5,自引:0,他引:5
系统地描述了我国近年来塑料模具材料研制、应用和模具材料标准的发展,介绍了一些新材料的牌号、化学成分、热处理工艺、性能和用途,并对我国塑料模具材料今后的发展提出了一些建议。 相似文献
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本文阐述了计算机铝合金磁盘基片的镜面车削技术。讨论了影响磁盘基片加工精度及粗糙度的主要因素以及有关磁盘加工车床,金刚石车刀,工件材质,工作环境和切削条件等方面的问题。 相似文献