自由曲面加工理论与应用(第03讲--刀具路径生成算法概述)

自由曲面加工理论与应用
第03讲--刀具路径生成算法概述
刀具路径生成方法的分类
（Taxonomy of tool-path generation）
❑刀具路径生成方法包含的要素（Tool-path generation (TPG) mechanism）
•1）刀具路径规划的区域(Path-planning domain)
在二维区域内规划走刀模式（toolpath patterns），生成刀
具路径
（2D domain where tool-path patterns are planned）
•2）刀具路径生成的曲面(Path-generation surface)
在CC-surface或CL-surface等3D surface上生成刀具路径
（3D surface →CC-surface or CL-surface）。

三种刀具路径规划的区域（Three types of Path-planning domains）
1)参数区域(Parameter-domain(PD)): tool-paths are planned on the u,v-domain of the 3D surface r(u, v), and then they are mapped back to r(u, v).
2)导动平面(Guide-plane(GP)): tool-paths are planned on a separate “guide-plane”, and then they are projected on the surface.
3)导动曲面(Drive-surface(DS)): tool-path are defines as a series of intersection curves between “drive surfaces”and the pare-surface
❑TPG-mechanism = (PD CC , GP CC , DS CC , [PD CL ] , GP CL , DS CL )PD CC ——CC-based parameter-domain method
GP CC ——CC-based Cartesian tool-path
DS CC ——CC-based APT-type tool-path
PD CL ——CL-based parameter-domain method
GP CL ——CL-based Cartesian tool-path
DS CL ——CL-based APT-type tool-path
对3轴刀具路径生成而言，CL-based method have distinct advantedges over the traditional CC-based methods.
Note the combination ‘PD CL ’is optional because it is not likely to be employed in practice.
刀具路径生成方法（Tool-Path Generation Methods）
1) Conventional TPG Methods (CC-based methods)
2) CL-based Method (C-space method)
CC-based TPG methods
种类（对应于三种刀具路径规划的区域）
(1) Isoparametric method: CC-paths are planned on the parameter-domain
(2) CC-Cartesian method: Tool-paths are planned on a guide-plane
(3) APT method: Intersecting the part surface with a series of drive-surfaces.
过程（TPG procedure in CC-based methods）：
1) Mapping: computation of a CL-point for a given ¡domain-point¡.
2) Marching: find the next domain-point from the current point on the path.
3) Side stepping: find the initial domain-point on the next path.
Isoparametric Tool-Path Generation
刀具干涉（Cutter-interference）
❑刀具干涉的种类（Cutter interference types）•曲率干涉（CL-point interference）
gouging occurs at a CL-point.
•运动干涉（CL-line interference）
gouging occurs on a CL-line.
•碰撞（collision）
Dead center collision (round-endmill), holder collision and
shank collision
1）曲率干涉（CL-point interference）
Sufficient condition for concave-gouging：d > 1/ρ　,
2）运动干涉（CL-line interference ，Convex gouge)（1）凸干涉（Convex-gouge）
凸干涉避免方法（Convex gouge avoidance）
method：insert additional CL-points at q i(for i=1,2)参见：Ball-end cutter
interference avoidance
in NC machining of
sculptured surfaces.
CAD
（2）Round-endmill gouge and Vertical gouge (convex)
3）碰撞（collision）
三种（three types）：
Dead center collision (round-endmill) Holder collision
Shank collision
切削仿真和验证（Cutting Simulation and NC Verification）
❑切削仿真的几何模型（Geometric models used for cutting simulation）
Z-map model
Dexel model
Discrete vector model
Voxel model.
切削仿真的类型（Type of cut-sim）
•视觉仿真（Visual cut-sim）
To obtain a visual image of the machined-surface.
•几何仿真（Geometric cut-sim）
To examine the machined accuracy, usually down to 0.01mm.
•物理仿真（Physical cut-sim）
To verify cutting conditions (by computing excepted cutting forces).
Thanks…
谢谢！。