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高速切削塑性变形的本质是位错的不可逆运动与增殖,切削时固体的黏滞力与位错速度成正比,材料的黏性效应在材料的动态力学行为中起到越来越重要的作用,因此从流体的角度去理解比从固体的方面去认识更符合其特点。本文描述了高速切削的位错阻尼机理,建立了基于流体力学的高速切削理论模型,利用计算机模拟技术得到了高速切削时的速度场、压力场和应变率场,为高速切削研究提供了新的思路。通过分析计算结果得出如下结论:在刀尖上方存在速度滞止点,此处速度为零,压力最大,其位置变化影响着刀具寿命和工件已加工表面的质量;从压力最大点开始,压力值沿前刀面逐渐减小直到某处为零,此点即切屑与前刀面分离点;剪切面(刀尖与自由表面拐角处连线)上应变率最大,然后由此向外依次减小。
The nature of high-speed cutting plastic deformation is the irreversible movement and proliferation of dislocations. The viscosity of solid is proportional to the dislocation velocity during cutting, and the viscous effect of the material plays an increasingly important role in the dynamic mechanical behavior of the material. Therefore, from the fluid point of view to understand more than from the solid to recognize more in line with its characteristics. In this paper, the dislocation damping mechanism of high speed cutting is described. The theoretical model of high speed cutting based on fluid mechanics is established. The velocity field, pressure field and strain rate field of high speed cutting are obtained by computer simulation technology, which provides a new method for high speed cutting research Ideas. Through the analysis of the calculation results, the following conclusions are drawn: there is a velocity stagnation point above the tip of the tool, where the velocity is zero and the pressure is the largest. The position change affects the tool life and the quality of the machined surface of the workpiece. From the point of maximum pressure, The value decreases along the rake face until somewhere is zero, which is the point at which the chip separates from the rake face; the strain rate on the shearing face (the line connecting the tip to the free surface) is the highest and then outward Decrease