Programming by the plane curve unwrapped from the helix curve and cutting layer by layer, we created the variable pitch screw on the 3.5 axis NC milling.

文章基于3.5轴数控铣床，利用螺旋线展开的平面曲线编程，分层切削，加工出变螺距螺纹；

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A helix equation of time-varying pitch is established, revolving elliptic cylinder as equal angular velocity and rising as variable velocity at the same time.

建立了绕椭圆柱面以等角速度旋转，又以变速度上升的非定常螺距的螺旋线方程。

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