Electrocontact Discharge Dressing of a Resin-Bonded CBN Grinding Wheel and its Grinding Performance
Electrocontact Discharge Dressing of a Resin-Bonded CBN Grinding Wheel and its Grinding Performance
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树脂结合剂CBN砂轮电接触放电修整及其磨削性能
DOI：
10.4028/www.scientific.net/kem.238-239.327
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
K. Narita
中科院分区：
文献类型：
--
作者：
J. Tamaki;A. Kubo;Jixin Yan;K. Narita
采用电接触放电（ECD）方法修整导电树脂结合剂CBN砂轮，研究了火花放电和电弧放电两种放电方式对砂轮表面形貌的影响。结果发现，当施加火花放电区域的开路电压或低于20 V的电压时，CBN颗粒与树脂结合剂基体牢固地结合在一起，而覆盖CBN颗粒的镍涂层没有受到侵蚀。对合金钢进行切入磨削，并比较 ECD 方法和使用 GC 杯形砂轮的机械修整方法的磨削性能。当ECD修整采用火花放电模式时，磨削力显示出与GC杯轮法获得的磨削力相同的值。然而，砂轮磨损仅为原始值的二分之一，并且表面粗糙度的恶化程度低于 GC 杯形砂轮法的情况。引言在电接触放电（ECD）修整[1]中，通过施加直流电源的导电砂轮对旋转电极环进行切入磨削，电极切屑和导电结合剂之间发生放电，由于放电的热能而导致结合剂材料的局部腐蚀和吹落。作者[2]通过金属结合剂金刚石砂轮的ECD修整实验阐明，ECD方法甚至适用于非常细粒度的金刚石砂轮。然而，对于超级磨料涂有镍膜的导电树脂结合剂砂轮，有报道[3]，ECD方法不适用，因为镍涂层的选择性侵蚀导致超级磨料颗粒过度脱落。本工作的目的是寻找导电树脂结合剂CBN砂轮ECD修整的合适条件，并研究开路电压对砂轮表面形貌的影响。比较了ECD法修整的砂轮与GC杯形砂轮机械法修整的砂轮的磨削性能，讨论了ECD法在导电树脂结合剂CBN砂轮中的适用性。实验方法图1描绘了单极辅助ECD修整设备的示意图和电极的照片。将修整设备固定在平面磨床的工作台上，使电极的旋转轴位于砂轮宽度的中心线上，以进给量f对旋转电极进行切入磨削进行修整。电极由三环组成。中间有控制放电的电极环，内外有两个陶瓷结合剂GC磨料环。 重点工程材料在线：2003-04-15 ISSN：1662-9795，Vols。 238-239，第 327-332 页 doi:10.4028/www.scientific.net/KEM.238-239.327 © 2003 Trans Tech Publications Ltd，瑞士 保留所有权利。未经 Trans Tech Publications Ltd（www.scientific.net）书面许可，不得以任何形式或任何方式复制或传播本文的任何内容。 (Semanticscholar.org-13/03/20,21:50:20) 表 1 修整条件 B：导电树脂粘合 GC 环 20mm A：陶瓷粘合 GC 环 砂轮 旋转电极 石墨
A conductive resin-bonded CBN grinding wheel is dressed by means of an electrocontact discharge (ECD) method, and the effects of two discharge patterns, spark discharge and arc discharge, on the grinding wheel surface topography are investigated. It is found that the CBN grains are firmly held with the resin-bond matrix with no erosion of the nickel coating which covers the CBN grains when the open-circuit voltage in the spark discharge area or a voltage lower than 20 V is applied. An alloy steel is plunge ground and the grinding performance is compared between the ECD method and the mechanical dressing method using a GC cup-wheel. When the ECD dressing is applied in spark discharge mode, the grinding force shows the same value as that obtained from the GC cup-wheel method. However, the wheel wear is only one-half of the original value and the deterioration of surface roughness is lower than those in the case of the GC cup-wheel method. Introduction In the electrocontact discharge (ECD) dressing [1], a rotary electrode ring is plunge ground by an electro-conductive grinding wheel to which DC power is applied, and an electric discharge which occurs between an electrode swarf and the conductive bond yields local erosion and blowing-off of bond material due to the thermal energy of the electric discharge. The authors [2] have clarified through ECD dressing experiments for a metal-bonded diamond grinding wheel that the ECD method is applicable even for a very fine-grained diamond grinding wheel. However, for a conductive resin-bonded grinding wheel in which superabrasives are coated with nickel film, it has been reported [3] that the ECD method is not applicable because of the selective erosion of the nickel coating which causes an excessive dislodgement of the superabrasive grains. The purpose of this work is to find an appropriate condition for ECD dressing of the conductive resin-bonded CBN grinding wheel, and the effect of open-circuit voltage on the topography of the grinding wheel surface is investigated. The grinding performance is compared between the grinding wheel dressed by the ECD method and that dressed by a mechanical method using a GC cup-wheel, and the applicability of the ECD method to the conductive resin-bonded CBN grinding wheel is discussed. Experimental Method Figure 1 depicts a schematic of the one-pole-aided ECD dressing equipment and a photograph of an electrode. The dressing equipment is fixed on the table of a surface grinding machine so that the rotational axis of the electrode is positioned on the center-line of the grinding wheel width, and the dressing proceeds with the plunge grinding of the rotary electrode with a feed rate f. The electrode consists of triple rings. An electrode ring which governs the electrodischarge is arranged in the middle, and two vitrified-bonded GC abrasive rings enclose the inside and the outside Key Engineering Materials Online: 2003-04-15 ISSN: 1662-9795, Vols. 238-239, pp 327-332 doi:10.4028/www.scientific.net/KEM.238-239.327 © 2003 Trans Tech Publications Ltd, Switzerland All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications Ltd, www.scientific.net. (Semanticscholar.org-13/03/20,21:50:20) Table 1 Dressing conditions B:Conductive resin-bonded GC ring 20mm A:Vitrified-bonded GC ring Grinding wheel Rotary electrode Graphite