Research On Mechanism Of High Speed Point Grinding And Experimental Study Of Point Grinding Processing Of Difficult-to-grinding Materials

High speed point grinding is one of the most advanced and efficiency as a method super-high speed grinding, which integrates CNC technology, the technology of CBN wheel and super-high speed grinding. The technology is widely used in machining shafts, which is applied in the fields of machine tools, car manufacturing and tool manufacturing, but this technology is belonged to underway developing. The advantages of this technology are bringing low grinding force and low grinding temperature compared to common grinding, but the research on the mechanism and the controlling of grinding quality is rare in domestic and foreign countries. In conclusion, the details of the study are as following:(1)First, summarize the function, sort trait and development of the high and super-high speed grinding technology, the super-high speed point grinding was emphasized as a key content especially. The intention and significance of the topic research are also introduced.(2) In this paper, the process characteristics and correlative technologies of quick-point grinding have been researched. This paper emphasizes particularly on the abrasive geometry analysis on the quick-point grinding. Based on the technical feature of the point grinding, taking grinding variables angle a and0into the circular grinding geometric model, to analysis the variation tendency of each geometric parameters of the point grinding, which include the equivalent diameter, maximum contact length, undeformed chip thickness and the contact width in edge contact zone, with the change of the grinding variables angle. Through the experiment to verify the point-grinding can guarantee the machining accuracy in compare with the the Common external circular grinding.(3)Based on the Triangular heat source distribution model and the Rowe’s heat transfer model, building the point grinding model to calculating the theoretical grinding temperature in the contact zone, and take the variable angle into the model to analysis it’s effect on the grinding heat in the contact zone. This paper analysis the temperature field distribution on the surface and the undersurface near the contact zone with variable speed of the wheel and cutting depth by FEM when the slant angle is1°. Then do some experiment to checking the conclusion got from the FEM and test the rigidity of the workpiece to analysis The influences of the grinding parameters on micro structures of surface hardened layer of the cylindrical grinding-hardening test were studied. And at last, conduct an experiment to research the affection of variable angle to the grinding temperature.(4)Based on the Super depth of field microscopy to measure the grits’micro protrusion topography and statistics the geometric parameter, such as the abrasive diameter, length-width ratio, angle of cutting edge and the face number of grain. to build the universal grain model.(5)Adopting the3D FEM, and loading the X/Y component velocity by install the each velocity’s Amplitude curve,and then the result is the grain’s curve motion trajectory, to simulate the true grits track., and introduceing the maximum undeformed chip thickness as the grain’s maximum chip thickness. Analysis the change of grinding force and energy with the cutting depth’s growing. This part can be divide into two parts. One is to analysis the influence of different swivel angle on the grinding force;the another is to analysis the influence of different kind of grain and frictional factor, to simulate the effect of material adherency when grinding on the grinding force.(6)Through analyze the fracture theory in grinding brittle materials, the critical force and cutting depth are brought in. Consider the affection for cutting thickness from the swivel angle a between the wheel axis and the wheel axis by geometry analysis. The reasonable finite element model has been built to explore the critical conditions from brittle mode to ductile mode according indentation experiment. The conclusions were drawn at last to provide reference basis for grinding experiment of brittle materials.(7)The experiment of via the point grinding to process three kind of materials, including one kind of high-strength alloy, TC4,and two kind of ceramics, Si3N4and ZrO2.under different experiment conditions, test the finished workpieces’roughness,and analyzing the influence factors and their contributions on the surface integrity,to explore the Practical application of point grinding in the Processing of difficult-to-machine materials.(8)Summarize the conclusions from the paper and give the rational suggestions for further research.