Research On Fundamental Design Theory And Grinding Technology For Micro End Mill

Micro-cutting is a kind of new micro-machining technology that based on traditionalmetal cutting. It is originated to micro-structure in micro-systems and incorporates manynew technologies. Micro cutting-tool is the executive element in micro-cutting system, soits design and fabrication technology plays an important role in micro-cutting. Microcutting-tool has become to be the bottleneck technique that restricted the development ofmicro-cutting. In this thesis, the fundamental technology of micro cutting-tool design andfabrication was researched. The main of this paper is as follows:1. Based on the tribological characteristic, a suitable choice method for microcutting-tool material was researched. Two kind of friction test with low load and heavy loadwere respectively carried out for sticking friction and sliding friction by considering thetribological conditions of the tool-workpiece-chip contact area in micro-cutting process.With the friction test, the influence of friction conditions on tribological character fordifferent material pair of tool-workpiece were analysised. The friction mechanism wasresearched also. The results indicated that different rubbing pairs had different frictionproperties under different speeds or loads; for stainless steel, high speed steel showed abetter friction performance in low speed and load, while cemented carbide has moreadvantages in high speed or high load. Based on the results of the friction test, a suitablechoice method was proposed for the micro cutting-tool material.2. Based on the dynamic characteristic of cutting-tool, a design method for toolstructure was researched. Forced on the special structure of micro end mill, a dynamicmodel of micro end mill was built based on the segmentation method by using theTimoshenko theory, which considering the effect of shear deformation and moment ofinertia, both. The convergence of the built model was analysised, and the accuracy of modelwas verified by comparing with the calculated result of ABAQUS and Euler model. Basedon the model we had built, the influence of structure parameters of micro end mill on thenatural frequency of tool, such as the tool tip diameter, tip aspect ratio, taper angle, wereresearch. 3. The geometric model and design method of tool edge structure of micro end millwas researched. Based on the geometry of cutting-tool, a universal model for the screwedge and a universal model for the groove of traditional helical end mills were built.Considering the difficulty of tool grinding in micro end mill with helical groove structure, anew design method for micro ball-end mill was proposed based on an elliptic ball-end mill.This tool not only has the S shape edge but also facilitating the process of manufacture.And the work angle of the new tool was calculated based on the geometric model.4. The new designed micro ball-end mill was grinded and a cutting test was carried outto verify the cutting performance of the tool. A new fabrication method was researchedbased on the feature of the new micro ball-end mill, and a grinding test was also carried out.From the detection of laser microscope, a satisfactory edge was got. By a micro-cutting test,the cutting performance of the new designed tool was verified.