SIMPLIFICATION IN POLISHING METAL MOLD OF CEMENTED CARBIDE MACHINED BY EDM USING OXIDATION

简化氧化电火花加工硬质合金金属模具的抛光

• 批准号: 08650838
• 负责人: TAMURA Takeo
• 金额: $ 1.47万
• 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: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08650838/
• 关键词: ELECTRICAL DISCHARGE MACHINING; CEMENTED CARBIDE; HIGH-TEMPERATURE OXIDATION; SURFACE MODIFICATION; HEAT-AFFECTED ZONES; INDUCTION HEATING; METAL MOLD; 多孔質酸化層

Recently, the use of cemented carbides has become widespread for various kinds of meal molds because of their superior wear and heat resistance. However, the heat-affected zones (HAZ), in which ihere are many cracks and microcraters, are generated by electrical discharge machining (EDM) of cemented carbides during the metal mold manufacturing process.Under the present situation, HAZ are removed by polishing, which is dependent on hand finishing. However, this process extends the machining time and increases the cost of production of metal molds.Therefore, a surface modification method using oxidation is proposed as a new surface modification method instead of the mechanical removal one. The proposed method uses a high-temperature oxidation of the surface of cemented carbides, softening the layrs with many pores so that they can be easily removed by rubbing with a wire brush.The following results were obtained :(1) The heat-affected zones generated by EDM of cemented carbides could be completely removed by this oxidizing treatment. The oxidzed surface is comprised of cobalt and tungsten oxides.(2) The crystal structures remaining after oxide removal are transformed into the hexagonal lattice of tungsten carbide, WC,in a stable structure. Consequently, the surface modification method is expected to greatly facilitate polishing during the metal mold manufacturing process.

近年来，硬质合金因其优异的耐磨性和耐热性而广泛用于各种金属模具。然而，在金属模具制造过程中，硬质合金的放电加工(EDM)会产生热影响区(HAZ)，其中存在许多裂纹和微缩孔。在目前的情况下，HAZ是通过抛光去除的，抛光依赖于手工精加工。然而，该工艺延长了加工时间并增加了金属模具的生产成本。因此，提出了一种利用氧化的表面改性方法作为替代机械去除表面改性方法的新表面改性方法。该方法通过对硬质合金表面进行高温氧化，软化具有许多孔隙的层，以便用钢丝刷摩擦即可轻松去除它们。获得以下结果：（1）通过这种氧化处理，可以完全去除硬质合金电火花加工产生的热影响区。氧化表面由钴和钨的氧化物组成。(2)去除氧化物后剩余的晶体结构转变为稳定结构的六方晶格碳化钨WC。因此，表面改性方法有望极大地促进金属模具制造过程中的抛光。

项目成果

田村武夫: "酸化現象を利用した超硬合金放電加工面の改質" 精密工学会誌. 61,6. 824-828 (1995)

Takeo Tamura：“利用氧化现象对硬质合金的放电加工表面进行改性”，日本精密工程学会杂志 61,6（1995）。

小嶋久稔,田村武夫: "誘導加熱を用いた放電加工面の改質" 1996年度精密工学会秋季大会学術講演会論文集. 73-74 (1996)

Hisatoshi Kojima、Takeo Tamura：“使用感应加热对放电加工表面进行改性”1996 年日本精密工程学会秋季会议学术会议记录 73-74 (1996)。