Transient Phenomenon of Chip Generations and movements in hobbing

本研究旨在通过观察滚切过程中的瞬时现象，阐明滚刀磨损、被滚齿表面粗糙度与切屑产生之间的机理。进行了滚切和仿真试验，对切屑的飞行过程进行了测量，观察了切屑与刃口的分离情况。主要研究结果如下：(1)不同导热系数的刀具和加工材料的组合改变了切屑的卷曲等形状。根据切屑形状的不同，大致分为三种类型的切屑飞行轨迹。(2)切屑形状不同，一周前新切屑与附加切屑的干涉程度也不同。(3)在平板式飞刀上铣的情况下，用金属陶瓷刀具代替硬质合金刀具，容易使切屑从工件上飞出，建立了滚切仿真模型，用…软件模拟了单飞刀滚切时的加工情况更多相同的滚齿机和滚齿机。给出了仿真试验中飞刀切割瞬变现象的结果。(4)飞刀没有附着在飞刀前刀面上，导致涂层前刀面脱落。(5)在高速钢飞刀无涂层前刀面和干切削情况下，飞刀将附着在前刀面上的工件切割一圈后，旧的附着的切屑被新生产的切屑推出并飞走。(6)当切屑由上刀刃和侧面同时产生时，切屑在刀具的拐角处受到强烈干扰，切屑流动方向随切削刃截止点的变化而变化。在斜齿轮滚齿加工中，由于切断点在一侧刃口的根部，多次观察到切屑侧向附着在前刀面上的情况。这种现象被认为是附着在齿面上的侧向切屑脱落，导致表面质量劣化。较少

This research aims at clarification of mechanisms between hob wear, surface roughness of hobbed tooth and chip generation by observation of transient phenomenon in hobbing. Hobbing and simulation tests, measurement of chip's flight course and observation of separation between cutting edge and chip are performed. Their main results are summarized.(1) The shape of chip such as curl is changed by the combination of cutting tools and work materials having different heat conductivity. Three types of chip's flight courses are divided roughly owing to shapes of chips.(2) The interference between new chip and attached chip before one revolution is differed by shapes of chips. The interference of chips of annealed Cr-Mo steel (JIS SCM415) occurs easily.(3) Chips fly away from work-piece by using cermet tools rather than cemented carbide tools in the case of up milling with plane type flytool.Hobbing simulation is built up, that simulates cutting condition of hobbing by using single flytool with … More identical hob tooth and hobbing machine. The result of transient phenomenon of flytool cutting in simulation tests is shown.(4) The chip doesn't attach on the rake face of flytool, resulting in flying away in the case of coated rake face.(5) In the case of none coated rake face of high speed steel flytool and dry cutting, the flytool cuts in work-piece as attached on the rake face with the chip before one revolution, and then the old attached chip is pushed out by new produced chip and flies away.(6) The chip is interfered strongly at the comer of cutting edge when it is produced by both of the top cutting edge and side one at the same time, and flow out as changing the shape.(7) The flow direction of chip changes by the cut off point of the cutting edge. In helical gear hobbing, the cases that the chips attach sideways on the rake face are observed many times as the cut off point is at the root of one side cutting edge. This phenomenon is considered that the attached sideways chip is tom off on the tooth surface, resulting in degradation of surface quality. Less