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STUDY ON HIGHER REMOVAL RATE OF CEMENTED CARBIDE BY EDM

电火花加工较高硬质合金去除率的研究

基本信息

批准号：
12650111
负责人：
TAMURA Takeo
金额：
$ 1.15万
依托单位：
NIIGATA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12650111/
关键词：
EDM cemented carbide deionized water dissolved oxygen material removal rate decomposed and oxidized reaction ワイヤ放電加工

项目摘要

It was found that when a cemented carbide is heated at elevated temperature in the air, a tungsten carbide WC can be decomposed into tungsten and carbon at about 620 ℃. Generally, the machinability with electrical discharge machining (EDM) is governed by thermal than by mechanical material properties. If a cemented carbide can be machined by EDM based on the decomposition of WC, it is possible to machine a cemented carbide at a lower temperature of 620 ℃. In this study, the various experiments were conducted to establish the EDM with higher material removal rate, and the following results are obtained.(1) Explanation of decomposed process for cemented carbides machined by EDM in waterA tungsten carbide can be decomposed into tungsten and carbon under the existence of oxygen. As the EDM will be done using deionized water as a dielectric liquid, the dissolved oxygen (DO) and oxygen generated electrolytically exist in the deionized water. The following results are obtained.(1) Only a tungsten W was detected in the debris through the X-ray diffraction pattern.(2) Carbon separated from WC reacts with oxygen in the deionized water to form carbon dioxide gas.From above results, it was found that when cemented carbides were machined by EDM in the deionized water, tungsten carbide WC could be decomposed into tungsten and carbon.(2) The influence of DO concentration on the material removal rateIn general the maximum amounts of oxygen which can be dissolved in the water is 20 mg/l. The EDM was done in the deionized water where the dissolved oxygen is supersaturated. In the case of the deionized water with higher concentrated DO, the material removal rate is about 30 % higher than that of the deionized water with lower concentrated DO.

结果表明，当硬质合金在空气中高温加热时，碳化钨WC可在620 ℃左右分解为钨和碳。通常，电火花加工（EDM）的可加工性由热而不是由机械材料性质决定。如果可以基于WC的分解通过EDM加工硬质合金，则可以在620 ℃的较低温度下加工硬质合金。在本研究中，进行了各种实验，以建立具有较高的材料去除率的电火花加工，并获得了以下结果。(1)水中电火花加工硬质合金分解过程的解释碳化钨在氧气存在下分解为钨和碳。由于EDM将使用去离子水作为电介质液体进行，溶解氧（DO）和电解产生的氧存在于去离子水中。获得了以下结果。(1)通过X射线衍射图在碎片中仅检测到钨W。(2)WC中析出的碳在去离子水中与氧气反应生成二氧化碳气体，由此发现，在去离子水中电火花加工硬质合金时，碳化钨WC分解为钨和碳。(2)溶解氧浓度对材料去除率的影响一般来说，溶解在水中的最大氧含量为20 mg/l。EDM在溶解氧过饱和的去离子水中进行。在具有较高浓度DO的去离子水的情况下，材料去除速率比具有较低浓度DO的去离子水高约30%。