用展成法加工渐开线齿轮,当刀具O0的齿顶圆超出理论啮合线的极限点N1(图1)时,将使工件齿轮O1发生根切。 刀具齿顶圆(半径为 0)与点N1的距离 r为式中,啮合角a01应满足下式; 显然,当　r变小,则根切倾向增大,当 r0,则发生根切。 r与模数m的比值 r*称为根切系数。 上式即表明了根 The involute gear is machined by the spreading method. When the tip circle of the tool O0 exceeds the limit point N1 of the theoretical meshing line (FIG. 1), the work gear O1 will be undercut. Tool tip top circle (radius 0) and the distance between the point N1 N1 is the formula, the meshing angle a01 should satisfy the following formula; Obviously, when r becomes smaller, the root cut tends to increase, when r0, the root cut occurs. The ratio of r to the modulus m r * is called the root cut coefficient. The above formula shows the root