Fundamental Study On Utilization Of Heat Pipe Technology To Enhance Heat Transfer In The Grinding Contact Zone

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.