【作者】 马可；

【导师】 徐鸿钧；

【作者基本信息】 南京航空航天大学 ， 机械制造及其自动化， 2011， 博士

【摘要】 制约高效深切磨削进一步发展的主要瓶颈之一是弧区热量积聚导致的磨削温度过高和工件表面的热损伤。以往只需将足量的磨削液引入到弧区便可确保换热效果的看法其实是一种误解。磨削过程中，在超过临界值的高磨削热流密度下，即使有再多的磨削液进入弧区也无济于事，因为磨削液既已处于成膜沸腾状态，由于工件表面所覆盖的汽膜层的阻挡，磨削液很难真正起到换热作用，如不及时采取相应的措施，工件必定很快发生烧伤。从另外一方面讲，磨削液的大量使用本身也与当前绿色制造的发展趋势相悖。本文从这种现状出发，基于绿色制造的理念，提出了一项可望突破高效深切磨弧区换热瓶颈的全新构想——基于热管的磨削弧区强化换热。该项构想的核心是基于旋（回）转热管技术的传热原理，采用一定的结构和工艺，使磨削弧区的热量直接导入热管蒸发端并经热管迅速疏导出去，使冷却的重心由工件转向砂轮，以达到强化弧区换热、提高材料去除率的目的。围绕此构想，本文主要完成了以下几项工作：1、研制了热管制作平台，在此平台上制作了一个热管磨头。对热管磨头的传热特性进行了测试，并进行了铣磨钛合金试验，结果表明，在其它工艺参数相同的条件下，使用热管磨头时磨削温度低于普通磨头30%以上，证明了热管技术用于磨削弧区强化换热的可行性。2、提出了环形热管砂轮的全新构想，并建立了其简化传热模型。通过求解模型，得到了环形热管砂轮内外壁温度的计算公式。在一定的初始条件下对不同热流密度下的内外壁温度进行了计算，并将计算结果与不带热管的普通砂轮对比，发现环形热管砂轮可以在很大磨削弧区热流密度条件下将其内外壁温度控制在很低水平，这一结果从理论计算上证明了环形热管砂轮的换热潜力。3、设计了环形热管砂轮的基体结构并加工制作，搭建了能定量模拟磨削弧区发热并准确测定弧区温度的模拟热管砂轮传热特性试验平台。对环形热管砂轮基体进行模拟弧区加热试验，最后对比普通砂轮基体的试验结果，证实了其换热优势。4、使用电镀CBN环形热管砂轮和普通电镀CBN砂轮进行了45钢缓进给干磨和往复干磨对比测温试验。试验结果表明，在没有磨削液参与的干磨条件下，环形热管砂轮可以直接疏导磨削热，大幅降低磨削温度。最后进行了一组有磨削液的钛合金TC4缓磨测温试验，结果发现在普通砂轮发生烧伤的工艺参数条件下，使用环形热管砂轮磨削不会出现烧伤，这一结果证明了环形热管砂轮可以依靠其优异的换热能力提高磨削弧区临界热流密度，防止磨削液成膜沸腾造成的烧伤，进而提高磨削材料去除率。更多还原

【Abstract】 One of the bottlenecks which impose restrictions on high efficicency grinding’s furtherdevelopment is high grinding temperature and the burn of the workpiece surface caused by the heataccumulaiton in the grinding contact zone. The traditional point considers that leading a large quantityof coolant into the grinding contact zone can insure the effect on heat exchange is a kind ofmisconception actually. During the grinding process, once the coolant is being film boiling state, thevapor film on the workpiece surface will make the coolant difficult to play a role of heat exchange,consequently, it is no use of much more coolant entering into the grinding contact zone under thecondition of high heat flux exceeding its critial value. So, the workpiece surface will burnimmediately if there is no measure to be carried into effect at this time. Furthermore, abundant use ofcoolant is intradiciton with the trend of green manufacturing at present.Based on the present status mentioned above and green manufacturing conception, a brand-newidea about enhancing heat transfer in grinding zone based on heat pipe technology is put forward inthis paper which will hopfully breakthrough the bottleneck of the heat exchange int the gringdingcontact zone. The kernel of the idea is to use some structures and processes based on rotating heatpipe principle to lead the heat in the grinding contact zone to the vapor section of the heat pipe thus tobe transferred to the circumstance, so that the cooling focal point will move from workpiece togrinding wheel in order to enhance heat transfer in grinding contact zone and decrease the grindingtemperature. According to this idea, some works have been done in this paper:1. A platform for making heat pipe was developed and a heat pipe grinding head was made on it.The transfer characteristics of the heat pipe grinding head were test and the milling-grinding titaniumalloy experiment with it was conducted. The results of the expeirment indicate that, the grindingtemperature of the heat pipe grinding head is30%lower than normal grinding head and it proves thefeasibility of using heat pipe to enhance the heat transfer of grinding contact zone.2. An tentative idea of Loop Heat Pipe Grinding Wheel (LHPGW) was put forward and it’ssimplified model was established by the way of mathematical modeling. According to solving themodel, calculating formulas of external wall temperature and internal wall temperature of theLHPGW were obtained. The temperature of LHPGW’s external and internal wall were calculated withthe formulas then cmpared with the normal grinding wheel without heat pipe.The results indicate thatthe LHPGW could take the internal and external wall temperauture on a very low level under the condition of a very high heat flux from the grinding contact zone. This result proves that the loop heatpipe in the LHPGW has great potential on heat transfer.3. The LHPGW matrix’s structure was designed whereafter was produced. The simulating heattransfer characteristics of LHPGW platform was developed to simulate the heating condition of thegrinding contact zone quantitatively and measure the grinding temperature accurately. On the basis ofthe platform, a simulating heating expeirment of LHPGW was conducted. The experiment resultsprove that the LHPGW’s superiority in heating transfer contrast with the normal grinding wheel.4. The electroplating CBN LHPGW and normal electroplating CBN grinding wheel without heatpipe were respectively used to conduct dry creep feed grinding and dry traverse grinding on45steel.The experiment results prove that the LHPGW can remove the grinding heat directly and decrease thegrinding temperature greatly. Finally, a creep feed grinding experiment with grinding liquid of TC4titanium alloy was conducted. The experiment results show that the workpiece was not to be burnedusing LHPGW on the procesing parameter values which the workpicece was burned with normalgrinding wheel without heat pipe. This proved that the LHPGW could increase the critical heat flux ofthe grinding contact zone and prevent the burn due to the film boiling, thus increase the materialremoval rate of the grinding.更多还原