激光诱导氧化辅助微细铣削硬质合金的基础研究

发布时间：2018-08-26 15:38

【摘要】：硬质合金材料具有硬度高、耐磨、强度和韧性较好、耐热、耐腐蚀等优良特性,主要应用于金属加工的刀具、地质矿山工具、耐磨零件和模具等领域。然而,硬质合金的加工性能差,为改善微细切削硬质合金时存在刀具寿命低、加工效率低和加工质量差等问题,本文提出了激光诱导氧化辅助微细铣削复合加工工艺,利用激光辐射硬质合金工件的待加工区域,使其发生快速可控氧化,生成结构疏松的氧化物,改善材料的切削性能,大幅度提高加工效率、刀具寿命和加工质量。本文进行了激光诱导氧化辅助微细铣削硬质合金的基础研究,主要工作和成果如下:(1)建立了激光辐射下硬质合金的三维瞬态传热模型,对脉冲激光辐射下YG20硬质合金的温度场分布进行了仿真分析;仿真研究了激光平均功率、激光频率、扫描速度和光斑直径等参数对工件温度场分布的影响规律。(2)对YG20硬质合金进行了常规氧化试验,分析了氧化物组分和微观结构。根据常规氧化的试验结果和温度场仿真结果,对YG20进行了激光诱导氧化试验;分析了激光参数和氧化环境对硬质合金氧化反应的影响规律,制定了基于疏松氧化物的激光诱导氧化调控策略。结果表明:YG20硬质合金高温下的氧化产物主要是CoWO4和WO3;大气环境条件下,当激光光斑直径为0.5mm、扫描速度为0.5mm/s、频率小于33kHz、激光平均功率功率为5~6W时,材料发生氧化反应,生成结构疏松的氧化物;功率大于等于7W后,材料发生融化烧蚀;富氧条件下,功率大于等于6W后,材料即发生烧蚀,喷射氧气的氧化辅助作用不明显。(3)对比分析了激光诱导氧化辅助微细铣削工艺与微细铣削工艺,研究了两种工艺在加工YG20微结构过程中铣削力、加工质量和微细刀具寿命。结果表明采用激光诱导氧化辅助微细铣削工艺,可大幅度降低铣削力、提高刀具寿命,相同铣削参数下,随着铣削长度的增加,激光诱导氧化辅助微细铣削加工表面的粗糙度值小于微细铣削,能得到更好的表面加工质量。
[Abstract]:Cemented carbide materials have high hardness, wear resistance, good strength and toughness, heat resistance, corrosion resistance and other excellent properties, mainly used in metal processing tools, geological mining tools, wear-resistant parts and molds and other fields. In this paper, a laser-induced oxidation-assisted micro-milling compound machining process is proposed, in which the area to be processed is irradiated by laser, and the oxides with loose structure are produced. The cutting performance is improved, the machining efficiency, tool life and machining quality are greatly improved. The basic research on laser-induced oxidation assisted micro-milling of cemented carbide is carried out. The main work and achievements are as follows: (1) A three-dimensional transient heat transfer model of cemented carbide under laser irradiation is established, and the temperature field distribution of YG20 cemented carbide under pulsed laser irradiation is simulated and analyzed. (2) The conventional oxidation test of YG20 cemented carbide was carried out, and the oxide composition and microstructure were analyzed. According to the results of conventional oxidation test and simulation results of temperature field, the laser-induced oxidation test of YG20 was carried out, and the laser parameters and oxidation environment were analyzed. The results show that the oxidation products of YG20 cemented carbide at high temperature are mainly CoWO4 and WO3. Under atmospheric environment, when the laser spot diameter is 0.5mm, the scanning speed is 0.5mm/s, the frequency is less than 33 kHz, the average power of laser is 0.5mm/s. When the power is greater than or equal to 7W, the material will melt and ablate; when the power is greater than or equal to 6W, the material will ablate, and the assistant effect of oxygen injection oxidation is not obvious. (3) The laser-induced oxidation assisted micro-milling process and micro-milling worker are compared and analyzed. The results show that the laser-induced oxidation-assisted micro-milling process can greatly reduce the milling force and improve the tool life. Under the same milling parameters, with the increase of milling length, laser-induced oxidation-assisted micro-milling can be added. The roughness of the work surface is smaller than that of the micro milling, and the surface quality can be better.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG54

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