Abstract:

For milling of  free-form impeller channel using nonorthogonal 4-axis machine,a tool axis control method was proposed, which interpolated tool axis by rotating it through a revolution axis in a constraint surface.Through analyses of the tool axis constraint conditions,a unit cone which met the constraint conditions was established in work coordinate system.An algorithm was presented to calculate initial tool axis of  the clean-up machining,then the interference-free tool axis of every contact point was generated in a clean-up tool path.Sequentially the surface area on the unit cone was calculated, which determined by the corresponding clear-up tool axis,and interpolated clean-up tool axis by rotating it in a same angle on this area to get the tool axis of the impeller channel milling,finally a machine kinematics constraints was established to smooth it.Examples show that the method can calculate the smooth and interference-free tool axis of the impeller channel accurately and efficiently when it is machined by using non-orthogonal 4-axis machine.

Key words: impeller channel, non-orthogonal 4-axis machining, rotating interpolation, tool axis control

摘要：

针对自由曲面叶轮流道非正交四轴加工,提出了一种在刀轴约束面上旋转插值的刀轴控制方法。通过分析刀轴约束条件,在工件坐标系下建立满足约束条件的单位圆锥面。采用清根切触点处初始刀轴的计算方法求解清根轨迹上每一个切触点处无干涉的刀轴矢量。按照清根切触点序列依次计算流道两侧对应清根刀轴在单位圆锥面上确定的扇形曲面区域,并在该区域等角度旋转插值清根刀轴,从而获得流道加工的刀轴矢量,最后建立机床运动学约束条件并对其进行光顺处理。结果表明,该方法能够准确有效地计算叶轮流道非正交四轴加工光滑且无干涉的刀轴矢量。

关键词: 叶轮流道, 非正交四轴加工, 旋转插值, 刀轴控制