二、齿轮精车的切削运动学(续) (一)预备定理 如空间曲线A在平面C上的投影曲线为A’,又曲线A上任一点α在曲线A’上的投影点为α’,则过α’关于曲线A’的切线α’t’,就是空间曲线A过α点之切线at在C面的投影(图11)。 关于它的证明可见一般的微分几何。 (二)刀具的工作表面及 Second, the fine kinematics of the cutters (Continued) (a) the preparatory theorem, such as space curve A in the plane C on the projection curve A ’, and any point on the curve A on the curve A’ projection point α ’ Then α ’tangent α’t’ to curve A ’is the projection of the tangent at at α of the spatial curve A over the C surface (Figure 11). The proof on it shows the general differential geometry. (B) the working surface of the tool and