Experimental And Simulation Study On The High-speed And High Efficient Grinding Of The Hardened Steel Of Narrow-and-deep Slot

In the daily production, it is common that the slot is,often than not, used in rotorstructure of various pump widely whose width is less than2mm,depth is over6mm,and length spectrum is0-50mm, but the realization of the high precisionmachining process has been difficult. This issue aims to apply creep feed grinding tonarrow-deep slot machining by vitrified bonded CBN grinding wheel, what is more，the high efficient deep grinding that functioned in narrow-deep slot by electroplatedCBN grinding wheel is rigorous considered, further study about narrow-deep slotgrinding and high-speed deep grinding mechanisms has been carried out discreetly, acouple of grinding wheel processing are developed which is on the basis ofhigh-efficiency in narrow-deep slot machining, at the premise of surface integrity ofthe workpiece, which services as a catalyst in prompting the application of thosetechnologies in engineering. This paper records the following researches has beentook out by making full use of the experiment equipments:(1) The narrow-deep slot has been processed by vitrified bonded CBN andelectroplated CBN grinding wheel at creep speed, meanwhile, the electroplated CBNgrinding wheel was applied to effective deep grinding test with a high speed. The testresults and grinding mechanism were analyzed, results show that when the maximumnot deformation cutting thickness is the same, specific grinding energy of vitrifiedgrinding wheel can be significantly greater than electroplated grinding wheel.Thecutting performance of electroplated grinding wheel is better than vitrified grindingwheel. Under the same grinding rate, the increase of cutting depth has more influencethan the increase of feed speed on grinding temperature. Both sides grinding fluid jetand down grinding are more suitable to narrow groove grinding.(2) In the paper, the influence of different grinding parameters on the surfacemorphology and surface roughness of workpieces grinded by this two different kindsof grinding wheels has been analyzed. And as for the grinding process of these twodifferent kinds of grinding wheels, the surface defects that are easy to occur, thesurface micro structure and micro hardness changes with different grindingparameters are analyzed.We can learn that materials removal is mainly for plasticremoval, with a small amount of brittleness removal under some parameters. Thesurface texture of workpieces that grinded by electroplated grinding wheel is clear, the trench on the surface of workpiece grinded by vitrified grinding wheel is less, thesurface is more smoother and roughness is better than the electroplated grindingwheel, But when using vitrified grinding wheel surfaces that are grinded are morelikely to appear surface defects such as:surface crack, surface scratches and smallburns and so on. Narrow deep slot material grinding surface is easy to occur a whitelayer of hardness is higher than the matrix organization. subsurface is easy to form thesoftening layer which the hardness is less than the matrix, the surface of themetamorphic layer thickness grinded by vitrified grinding wheel grinding is less thanelectroplated grinding wheel.(3) For narrow deep groove grinding, the workpiece width is narrower than thelength of the grinding contact zone theory under the condition of grinding temperatureprediction and process parameter selection problem,for narrow deep groove grindingthe transient temperature field of3rd finite element simulation has been analyzed.Result shows that they have good consistency, and improving the feed speed of thegrinding have a greater influence on the difference between grinding zone temperatureand machined surface temperature. Combined with the changes of grindingtemperature, changes of the surface micro hardness value and changes of subsurfacemicro structure, the metamorphic layer depth of subsurface were analyzed, resultsshow that the experiment and the simulation of metamorphic layer depth has a goodcorresponding relation, further proved that the accuracy of the simulation and thefeasibility of prediction of under different grinding parameters in of the metamorphiclayer thickness caused by grinding temperature.(4) Combining with the previous mechanism and the analysis of test results, theprocess parameters have been optimized, we get the result that: Grinding wheel linearvelocity at about45m/s, the feed speed is around100mm/min, the machiningefficiency and surface quality are the optimal. The reasonable selection of grindingwheel, grinding condition and the dosage of grinding, Guarantee cooling fully, Andkeep the shapen of the wheel has important role in improvements on the processparameters and improvement of machining efficiency.