STUDY ON REDUCTION OF POLISHING TIME OF METAL MOLD USING LASER IRRADIATION

激光照射缩短金属模具抛光时间的研究

• 批准号: 14550097
• 负责人: TAMURA Takeo
• 金额: $ 1.6万
• 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: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14550097/
• 关键词: EDM; laser irradiation; crack; polishing process; surface roughness; metal mold; 残留応力; 表面粗さ

At present, the cold working die steel, SKD11 is commonly being used as the metal molds due to its superior wear and corrosion resistance. In electrical discharge machining(EDM) of die steel, a hard white layer, that is different from the base metal, is formed on the metal mold surface causing rapid heating and cooling. Cracks and micro-craters appear on the surface of white layer depending machining conditions used. Such heat-affected zones(HAZ) can greatly shorten the life of metal molds. Therefore, the removal of this layer after EDM is necessary. Under the present situation, HAZ is removed by hand finishing. However, this process extends the machining time and raises the price of metal mold manufacturing.Therefore, a laser surface modification with melting has been proposed as a new surface modification method instead of the mechanical removal method. This method releases defects such as cracks and micro-craters and improves surface roughness using melting and solidifying HAZ by us … More ing a laser beam as the heat source. In this study, the laser beam was irradiated in three-dimensional metal mold with a area of 50 x 50mm^2. The surface modification was conducted using a 1kW CW carbon-dioxide laser. Argon gas was used on the metal mold coaxial with the laser beam in order to avoid oxidation of the surface. The laser beam was irradiated onto the electrical discharge machined surface with a laser output power of 800W, a feed speed of200 mm/min, a defocused condition of 5mm and step width of 1mm. As the result, the following conclusions are obtained.(1)Surface defects such as cracks and micro-craters generated by EDM could be released due to melting of surface layer. Subsequently, a melting layer could be obtained which is distributed uniformly after irradiation. It could be therefore shown that the new surface modification method improved the electrical discharge machined surface.(2)The surface roughness of about 25μmRy in the electrical discharge machined surface of metal mold could be decreased to 2〜5μmRy due to the overlapped laser treatment. The increase in surface roughness could be observed in the case of overlapped laser treatment surfaces. Less

目前，冷作模具钢SKD 11由于其上级耐磨性和耐蚀性而被广泛用作金属模具。在模具钢的电火花加工（EDM）中，在金属模具表面上形成不同于基底金属的硬白色层，引起快速加热和冷却。白色层的表面会出现裂纹和微坑，这取决于所使用的加工条件。这样的热影响区（HAZ）会大大缩短金属模具的寿命。因此，在电火花加工后去除该层是必要的。在目前的情况下，热影响区是通过手工精加工去除的。然而，这种方法延长了加工时间，提高了金属模具制造的价格，因此，激光表面改性与熔化已被提出作为一种新的表面改性方法，而不是机械去除方法。该方法利用热影响区的熔化和凝固，消除裂纹和微坑等缺陷，提高表面粗糙度 ...更多信息 使用激光束作为热源。在这项研究中，激光束照射在三维金属模具中，面积为50 x 50 mm^2。采用1 kW连续波二氧化碳激光器进行表面改性。在与激光束同轴的金属模具上使用氩气，以避免表面氧化。在激光输出功率为800 W、进给速度为200 mm/min、离焦量为5 mm、台阶宽度为1 mm的条件下，将激光束照射到电火花加工表面上。作为结果，得到以下结论。（1）电火花加工产生的裂纹、微坑等表面缺陷会由于表面层的熔化而释放。随后，可以获得在照射后均匀分布的熔融层。因此，可以表明，新的表面改性方法改善了电火花加工表面。（2）金属模具电火花加工表面的粗糙度约为25μ mRy，经激光叠加处理后，表面粗糙度可降低到25 μmRy。在重叠激光处理表面的情况下，可以观察到表面粗糙度的增加。少

项目成果

田村武夫, 小林禎将: "レーザビームを用いた冷間ダイス鋼放電加工面の改質"精密工学会誌. 68・3. 425-429 (2002)

田村武夫、小林贞正：“利用激光束对冷模具钢的放电加工表面进行改性”，日本精密工程学会杂志 68・3（2002 年）。