Transient Phenomenon of Chip Generations and movements in hobbing

本研究旨在通过对滚刀加工过程中瞬态现象的观察，阐明滚刀磨损、滚刀齿表面粗糙度与切屑产生之间的机理。进行了滚刀加工和模拟试验，测量了切屑的飞行轨迹，观察了切削刃与切屑的分离情况。总结了他们的主要成果。(1)刀具与具有不同导热系数的工件材料相结合，会改变卷曲等切屑的形状。根据芯片的形状，将芯片的飞行路线大致分为三种。(2)新芯片与附芯片在一圈之前的干扰因芯片形状不同而不同。退火Cr-Mo钢（JIS SCM415）容易产生切屑干扰。(3)用平面飞刀上铣削时，切屑飞离工件是用金属陶瓷刀具而不是硬质合金刀具。建立了滚刀加工仿真模型，模拟了在滚刀齿数与滚刀机相同的情况下，使用单个飞刀进行滚刀加工时的切削条件。给出了仿真试验中飞刀切削瞬态现象的结果。(4)在涂覆前刀面的情况下，屑没有附着在飞刀前刀面上，导致飞刀脱落。(5)在高速钢飞刀无涂层前刀面干切削的情况下，飞刀在转动一圈之前，将工件与切屑附着在前刀面上，原有的附着切屑被新产生的切屑推出，飞走。(6)上切刃和侧切刃同时产生切屑时，切屑在刃口角处受到强烈干扰，并随着形状的改变而流出。(7)切屑的流动方向因切削刃的切断点而改变。在斜齿轮滚齿，情况下，芯片附在侧面上的耙面多次观察到的切断点是在一个侧面切削刃的根。这种现象被认为是附着在齿面上的侧边切屑脱落，导致齿面质量下降。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