Study On High Efficiency Grinding With Heat Pipe Grinding Wheels

At present, one of the most problems exposed in the high efficiency grinding of strength andtoughness difficult-to-cut materials such as titanium alloy and superalloy is the workpiece burn causedby high grinding temperature in the grinding contact zone. The traditional theory considers thatmaking a large quantity of coolant into the grinding contact zone is an effective method to ensure itseffect of heat transfer enhancement. But actually, with the continuously increase of the grinding speed,grinding depth and workpiece feed-speed in the grinding, and superadd the grinding contact zone is arelatively closed area, it will be much more difficult to make coolant into the grinding contact zone.On the other hand, once the condition of heat flux input in the grinding contact zone exceeds thecritical value whose the coolant will occur to film boiling state, the coolant will loss the function ofheat exchange with the contact zone due to the obstruct of formed vapor film on the workpiecesurface.To solve the above trouble, one novel conceive about utilization of heat pipe technology to achievethe high efficiency grinding for strength and toughness difficult-to-cut materials is proposed in thispaper. Moreover, A new grinding wheel——heat pipe grinding wheel (HPGW) which owns a loopheat pipe in the wheel matrix is designed and manufactured. That new grinding wheel can rapidly takethe heat accumulating in the grinding contact zone away by means of its loop heat pipe in the grinding,and thus realize the purpose to further strengthen the heat transfer in the grinding contact zone as wellas reduce the grinding temperature. Based on the above mentioned conceive, some works have beencompleted in this paper:(1) Designed and manufactured one HPGW structure and then the sealing and structural strength ofHPGW were detected. The test results show that the sealing performance can guarantee HPGWhaving a long service life in future and the structural strength of HPGW is also able to satisfy the userequirements in the high efficiency grinding. After that, an electroplated CBN HPGW applied in thehigh efficiency grinding was developed through an established heat pipe making platform.(2) A heat transfer performance evaluation system platform for HPGW was developed. The heattransfer superiority of HPGW was verified obviously by comparing with the conventional grindingwheel without heat pipe and the influence of some factors on heat transfer capacity and start-up timeof HPGW were analyzed by the heat transfer experiments. According to the experiment results, heattransfer mechanism of HPGW in working condition was probed. Furthermore, the equivalent thermal resistances of HPGW and conventional grinding wheel without heat pipe were compared. The resultsprove that the heat transfer capacity of HPGW relative to conventional grinding wheel can beimproved by an order of magnitude due to the heat transfer effect of heat pipe, and thus further verifythe heat transfer potential of HPGW to take grinding heat away from the contact zone in the grinding.(3) Based on the Computational Fluid Dynamics software, a three-dimensional heat transfer modelof HPGW in the grinding was developed to analyze the influence of different parameters of thegrinding speed, cooling condition and heat flux input on the grinding temperature. The simulationresults show that the grinding temperature can be dramatically reduced by using HPGW in thegrinding.(4) Grinding contrast experiments using the electroplated CBN HPGW and conventionalelectroplated CBN grinding wheel without heat pipe were carried out in the grinding of Titaniumalloy Ti-6A1-6V and Inconel718under the same condition. Results suggest that using HPGW in thecreep feed grinding and high efficiency deep grinding can further take the grinding heat away fromthe grinding contact zone, and thus maintain the grinding temperature at a low level as well as preventthe burnout.