【摘要】：在難加工材料(如高溫合金)的磨削加工中,由于被加工材料的磨削比能高,且導(dǎo)熱性能差,使其在磨削加工中更容易出現(xiàn)弧區(qū)的熱量聚集,以致引起磨削燒傷、砂輪磨損等問(wèn)題。傳統(tǒng)的解決方案一般是:在加工過(guò)程中澆注大量的磨削液來(lái)實(shí)現(xiàn)磨削弧區(qū)的潤(rùn)滑和冷卻,然而,在磨削液的澆注過(guò)程中,能夠進(jìn)入到磨削弧區(qū)并真正起到換熱作用的液體量相對(duì)較少,并且,加工表面高溫導(dǎo)致磨削液會(huì)瞬間發(fā)生沸騰、汽化而在磨削表面形成蒸汽膜,不僅會(huì)阻礙新的磨削液進(jìn)入磨削區(qū),也會(huì)阻礙磨削弧區(qū)的熱量向外散發(fā)。因此,常規(guī)的澆注冷卻方式難以滿足磨削加工過(guò)程中高溫表面換熱的實(shí)際要求,高效的冷卻方法對(duì)磨削加工就顯得尤為重要。本文基于加壓內(nèi)冷卻技術(shù)與斷續(xù)磨削技術(shù)設(shè)計(jì)制作出加壓內(nèi)冷卻砂輪,以鎳基高溫合金GH4169作為加工對(duì)象,采用理論分析、有限元模擬和實(shí)驗(yàn)研究相結(jié)合的方法,研究了應(yīng)用加壓內(nèi)冷卻砂輪實(shí)現(xiàn)內(nèi)冷卻方式進(jìn)行磨削鎳基高溫合金時(shí)對(duì)磨削弧區(qū)溫度的控制能力。主要研究?jī)?nèi)容如下:(1)設(shè)計(jì)并制備出了用于平面磨削的加壓內(nèi)冷卻砂輪,基于移動(dòng)熱源理論建立了加壓內(nèi)冷卻砂輪平面磨削高溫合金的傳熱學(xué)模型,開(kāi)展了溫度場(chǎng)的理論計(jì)算,建立了仿真湍流模型。(2)基于熱源法建立了加壓內(nèi)冷卻砂輪平面磨削高溫合金的溫度場(chǎng)仿真模型,分析了熱流密度、砂輪轉(zhuǎn)速以及外部壓力三個(gè)因素分別對(duì)磨削弧區(qū)溫度的影響規(guī)律,并在相同熱流密度條件下對(duì)比了砂輪內(nèi)通加壓冷卻液與不加冷卻液兩種方式時(shí)的弧區(qū)溫度。(3)設(shè)計(jì)了單因素實(shí)驗(yàn)方案,進(jìn)行了利用加壓內(nèi)冷卻砂輪磨削鎳基高溫合金的實(shí)驗(yàn)研究,測(cè)量與對(duì)比了不同實(shí)驗(yàn)方案下使用不同冷卻方式時(shí)的磨削力和磨削溫度,觀察了已加工工件表面粗糙度和表面形貌,探討了利用新設(shè)計(jì)的加壓內(nèi)冷卻砂輪在進(jìn)行內(nèi)冷卻磨削高溫合金時(shí)對(duì)磨削弧區(qū)的冷卻效果、對(duì)工件已加工表面質(zhì)量的影響規(guī)律以及各參數(shù)的變化對(duì)磨削性能的影響規(guī)律。另外,將實(shí)驗(yàn)結(jié)果和模擬結(jié)果相結(jié)合的方式對(duì)比分析了不同熱流密度下的弧區(qū)溫度,對(duì)應(yīng)用加壓內(nèi)冷卻砂輪實(shí)現(xiàn)內(nèi)冷卻方式進(jìn)行磨削高溫合金時(shí)可以有效降低磨削弧區(qū)溫度的構(gòu)想的可行性進(jìn)行了分析。
[Abstract]:In the grinding of refractory materials (such as superalloy), because of the high specific grinding energy and poor thermal conductivity of the machined materials, the heat accumulation in the arc zone is more likely to occur in the grinding process, resulting in grinding burns. Grinding wheel wear and other problems. The traditional solution is that a large amount of grinding fluid is poured in the process of machining to realize the lubrication and cooling of the grinding arc area. However, in the process of pouring the grinding fluid, The amount of liquid that can enter the grinding arc area and really heat transfer is relatively small, and the high temperature of the machined surface will cause the grinding fluid to boil, vaporize and form steam film on the grinding surface. It not only prevents the new grinding fluid from entering the grinding area, but also prevents the heat emission from the grinding arc region. Therefore, the conventional casting cooling method is difficult to meet the actual requirements of high temperature surface heat transfer in grinding process, and efficient cooling method is particularly important for grinding process. Based on pressurized internal cooling technology and intermittent grinding technology, a pressurized internal cooling grinding wheel is designed and fabricated in this paper. The method of combining theoretical analysis, finite element simulation and experimental study is used to process nickel-based superalloy GH4169. The control ability of grinding arc temperature in grinding Ni-base superalloy by using pressurized internal cooling grinding wheel is studied in this paper. The main research contents are as follows: (1) A pressurized inner cooling grinding wheel for plane grinding is designed and fabricated. Based on the theory of moving heat source, a heat transfer model for plane grinding of superalloy with pressurized inner cooling grinding wheel is established. The theoretical calculation of temperature field is carried out, and the simulation turbulence model is established. (2) based on the heat source method, the temperature field simulation model of plane grinding superalloy with pressurized inner cooling grinding wheel is established, and the heat flux is analyzed. The three factors of grinding wheel speed and external pressure respectively affect the temperature of grinding arc zone. Under the same heat flux density, the arc zone temperature of the grinding wheel is compared with that of the cooling fluid with or without coolant. (3) A single factor experimental scheme is designed. The grinding force and temperature of Ni-base superalloy with different cooling methods under different experimental schemes were measured and compared, and the surface roughness and surface morphology of the machined workpiece were observed. This paper discusses the cooling effect of the newly designed pressurized internal cooling grinding wheel on the grinding arc zone, the influence of the surface quality of the workpiece and the influence of the parameters on the grinding performance when grinding the superalloy with internal cooling. In addition, the arc-zone temperature at different heat flux density is compared and analyzed by combining the experimental results with the simulated results. The feasibility of using pressurized internal cooling grinding wheel to realize internal cooling grinding of superalloy can effectively reduce the temperature of grinding arc zone is analyzed.
【學(xué)位授予單位】：湘潭大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：TG580.6
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本文編號(hào)：2327304