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81.
In-process evaluation of grit protrusion feature for fine diamond grinding wheel by means of electro-contact discharge dressing 总被引:1,自引:0,他引:1
This paper introduces a new in-process evaluation method for grit protrusion feature on wheel surface by monitoring discharge current trace during electro-contact discharge (ECD) dressing of metal-bonded fine diamond grinding wheel. First an impulse discharge machining experiment was carried out to investigate the correlation between metal bond removal and discharge parameters, namely discharge current Ie and discharge pulse duration τe. Then ECD dressing experiment for #600 diamond grinding wheel was conduced to analyses the quantitative effect of the discharge parameters (Ie and τe), derived from discharge current trace between wheel and dresser (electrode), on grit protrusion feature of wheel surface. The result shows that the grit protrusion feature is sensitive to the discharge parameters (Ie and τe) with reference to mean diamond grit size dgm. Further, the discharge parameters (Ie and τe) in ECD dressing should conform to the discharge variables’ requirement of , by which the grit protrusion feature may be evaluated and the dressing process variables may be determined. Finally, the in-process evaluation method was successfully applied to ECD dressing of #1500 diamond grinding wheel for valid grinding of hard-brittle materials. 相似文献
82.
83.
采用浸涂及烧结工艺制备了锌铬膜防腐涂层,用辉光放电光谱分析和纳米压痕/划痕试验技术对其成分和力学性能分别进行了深度剖面分析,并探讨了涂层组成对防腐和力学性能的影响。结果表明,各元素随深度呈不同的分布状态和变化趋势,并与烧结过程相关,硬度、弹性模量的深度分布与元素的深度分布相对应,膜层有较低的失效临界载荷。 相似文献
84.
较详细地介绍了数控高效放电展成加工技术,采用简单超长圆电极,通过计算机控制电极与工件的相对运动并对电极损耗进行在线检测和补偿,展成加工复杂形面的特殊材料的零件.电、机结合达到对难加工特殊材料的高效、高精度的展成加工. 相似文献
85.
86.
Biing Hwa Yan Hsien Chung Tsai Fuang Yuan Huang Long Chorng Lee 《International Journal of Machine Tools and Manufacture》2005,45(3):251-259
Alumina particle reinforced 6061 aluminum matrix composites (Al2O3p/6061Al) have excellent physical and chemical properties than those of a traditional metal; however, their poor machinability lead to worse surface quality and serious cutting tool wear. In this study, wire electrical discharge machining (WEDM) is adopted in machining Al2O3p/6061Al composite. In the experiments, machining parameters of pulse-on time were changed to explore their effects on machining performance, including the cutting speed, the width of slit and surface roughness. Moreover, the wire electrode is easily broken during the machining Al2O3p/6061Al composite, so this work comprehensively investigates into the locations of the broken wire and the reason of wire breaking.The experimental results indicate that the cutting speed (material removal rate), the surface roughness and the width of the slit of cutting test material significantly depend on volume fraction of reinforcement (Al2O3 particles). Furthermore, bands on the machined surface for cutting 20 vol.% Al2O3p/6061Al composite are easily formed, basically due to some embedded reinforcing Al2O3 particles on the surface of 6061 aluminum matrix, interrupt the machining process. Test results reveal that in machining Al2O3p/6061Al composites a very low wire tension, a high flushing rate and a high wire speed are required to prevent wire breakage; an appropriate servo voltage, a short pulse-on time, and a short pulse-off time, which are normally associated with a high cutting speed, have little effect on the surface roughness. 相似文献
87.
Galvannealed coating of high strength interstitial free (IF-HS) steel was characterised by Glow Discharge Optical Emission Spectroscopy (GDOES) and colour-etching techniques. Overalloyed galvannealed coatings with considerably high amount of Γ and Γ1 phases were detected in the first set of experiments. Necessary process modifications in galvannealing furnace were made to maximise the ä phase in the galvannealed coating, which was confirmed through GDOES and colour-etching techniques. As a result, an improvement in galvannealed product quality with a better powdering resistance property during forming has been achieved. 相似文献
88.
In many countries the most common polishing practice in die making is to hand polish the part as a finishing operation after the electro discharge machining process (EDM). The usual polishing abrasives are silicon carbide paper and diamond paste of different grit sizes.However, during the last decade researchers especially in Japan and the USA have tried to combine EDM and electrochemical machining (ECM) in one machine so as to use the positive aspects of each individual process. The ECM process uses high density, typically 50 A/cm2, and also a pulse current with a servo-controlled electrode. These investigators have mostly used sodium nitrate solutions (of different concentrations) as the electrolyte.This paper deals with an experiment that was undertaken in order to assess the effect of four different electrolytes in an electrochemical polishing process (ECP) on the surface topography of EDM surfaces. The primary set of 3D surface parameters was used as a basis to characterise the surface produced by the combined processes in different electrolytic media. 相似文献
89.
采用脉冲电流发生装置对Cr12模具钢中裂纹进行了脉冲放电止裂。放电后,裂纹尖端金属熔化形成焊口和压应力区,使裂纹尖端钝化,达到了止裂的目的。同时在裂纹尖端处得到了超细化的隐晶马氏体和细粒碳化物等微观组织,极大提高了裂纹尖端处的硬度、强韧性和耐磨性。 相似文献
90.