基于慢刀伺服粗铣环曲面的刀具路径规划与运动特性分析

Tool Path Planning and Kinematics Analysis of Rough Milling Toric Surface Based on STS Method

摘要:

为了获得高质量数控代码，采用慢刀伺服(Slow tool servo, STS)技术粗铣环曲面，对刀具路径规划策略和进给轴运动特性进行了分析。在阐述环曲面及慢刀伺服粗铣工艺系统基础上，采用几何投影法对比刀具偏置法和等距曲面法在刀具路径规划中的性能;选择球头铣刀进行粗铣加工，推导了内凹环曲面等距面方程;比较了2种曲面离散方法和2种曲线离散方法，得到了粗铣环曲面刀具路径规划优选策略。研究优选策略下进给坐标分量运动特性，基于Vericut软件进行了虚拟仿真加工。结果表明，使用几何投影法定性比较刀具偏置和等距离曲面的刀具路径规划性能，在实际中可行;刀具选择球头铣刀，用(a-rd)替换内凹环曲面方程中非一阶常数项a，即可获得内凹环曲面等距面方程;为了实现沿坐标轴的平稳进给，刀具路径规划策略为：等距曲面法、等距螺线导动法和等角度离散法;采用慢刀伺服技术加工环曲面，对Z轴动态响应有较高的要求。综上所述，采用等距曲面法规划刀具路径可行。以平滑坐标运动为目标规划刀具路径，可获得高质量的数控代码。研究结果为加工其他复杂面刀具路径规划提供参考。

Abstract:

When using slow tool servo (abbreviated as STS) technology to rough mill the toric surface, in order to obtain high-quality computer numerical control (abbreviated as CNC) code, the tool path planning strategy and the motion characteristics of the feed axis were studied. Based on the description of the toric surface and its STS process-system, the geometric projection method was used to describe the tool path planning process of the tool-offset method and the isometric surface method. The selected tool was a ball-end milling cutter, and the equation of the concave toric isometric surface was derived. Two surface discretization methods and two curve discretization methods were analyzed separately. The optimal path planning strategy for processing glasses lens was obtained. The motion characteristics of the feed coordinate components were studied. Based on the Vericut software, virtual machining was performed. The results showed that for qualitatively comparing the advantages and disadvantages of tool path planning with the tool-offset and the isometric surfaces, using the geometric projection method was feasible in practice;if the tool was a ball-end milling cutter, replacing the non-first-order constant term a in the concave toric equation with (a-rd), the equidistant surface equation can be obtained;to achieve smooth feed along the coordinate axes, the preferred toolpath planning strategies were as follows: the isometric surface method, the guiding rule of the equidistant spiral method, and the equal-angle discrete method;using the STS technology to machining the toric surface, there were higher requirements for the dynamic response of the Z-axis. In summary, it was feasible to use the isometric surface method to plan the tool path. Aiming at smooth coordinate's movement, planning the tool path was a useful attempt to obtain high-quality CNC code. The method had reference value for tool path planning of other complex curved surfaces.