五軸刀具中心點插補及刀具軸向控制之研究

Study on Tool Center Point Interpolation and Tool Orientation Control for Five-axis Machine

邱婉婷(Wan-Ting Chiu)

指導教授 ： 林明宗

國立虎尾科技大學/工程學院/機械設計工程研究所/碩士(2014年)

https://doi.org/10.6827/NFU.2014.00161

摘要

本研究提出一五軸刀具中心點插補及刀具軸向控制技術並應用於高速高精度五軸加工上。研究目的主要是針對五軸工具機多軸同動路徑，進行刀具中心點插補與控制，用以提升五軸工具機多軸同動的追蹤及輪廓精度。首先，依據五軸工具機之運動構型推導順逆向運動學方程式，再利用CAM軟體UG/NX規劃刀具路徑，接著使用其後處理器產生HEIDENHAIN控制器具有刀具中心點功能(M128/M129)之五軸NC碼。讀入並解譯NC碼後，將多軸同動路徑分成短線段長旋轉、長線段短旋轉、短線段短旋轉、長線段長旋轉等四種形式，並設計出能處理這四種TCP路徑的五軸插補演算法。此五軸插補演算法的主要步驟如下:(1)偵測NC線段間轉角並決定轉角速度;(2)比較TCP與旋轉軸的位移量選取主動軸，並使用推導的五軸速度公式決定此線段的最高進給速度;(3)針對NC線段、TCP及旋轉軸的位移量以及急衝限制決定最高進給速度;(4)使用主動軸進行速度規劃，並依據TCP與旋轉軸的位移量等比例規劃其速度;(5)利用逆向運動學方程式求得線性軸的速度。此演算法使用S型加減速針對TCP以及旋轉軸進給速度進行平滑化，同時也考慮刀具中心點以及五軸的速度、加速度以和急衝度限制以防止激發機台共振。最後，藉由在配備有PC-based控制器的桌上型五軸雕刻機上進行數值模擬和切削實驗，驗證本研究所提出的刀具中心點插補及刀具軸向控制技術能大幅提升五軸加工的追蹤及輪廓循跡性能。

關鍵字

刀具中心點 ； 刀具軸向平滑化 ； 急衝控制 ； 五軸工具機

並列摘要

In this paper, a tool center point (TCP) interpolation with tool axis orientation (TAO) smoothing technology is developed to achieve high-speed high-precision machining for five-axis machine tool. The objective is to improve tracking and contouring performance of TCP on multi-axis synchronized motions by using the proposed method.
Forward and inverse kinematics equations are derived based on kinematic configuration of five-axis machine tool. Tool paths are planned by means of CAM system, UG/NX. The postprocessor generates NC codes with TCP control function (M128/M129) which is compatible with the standard of HEIDENHAIN controller. After interpreting NC commands, multi-axis trajectories are classified into four types: Short segment large rotation(SSLR), long segment small rotation(LSSR), short segment small rotation(SSSR) and long segment large rotation (LSLR). The five-axis interpolation algorithms are proposed to deal with above TCP paths. The proposed algorithms include five steps: (1)Sharp corners between two NC blocks are detected and corner feedrates are determined; (2)Master axis is chosen by checking which movements of TCP and rotation axes is largest, maximum feedrate in the block is determined using derived five-axis velocity formulation; (3)Maximum feedrate is constrainted by the jerks and movements of TCP and rotary axes; (4)Feedrate palnning of master axis is performed, velocities of TCP and rotary axes are palnned according to movement ratios among master axis, TCP and rotary axes. (5)Velocities of linear axes are obtained using inverse kinematics equations. The proposed algorithms achieve feedrate smoothing on TCP and rotary axes by utlizing S-shape acceleration/ deceleration (ACC/DEC) method. Kinematic constraints of velocity, acceleration and jerk on TCP and five-axis are all taken into consideration to avoid exciting structure vibration of machine tools.
Finally, simulations and cutting experiments are carried out on a five-axis engraving machine with a PC-based controller. The experiment results shows the efficiency of the proposed technology in improvement of tarcking and contouring accuracy.

並列關鍵字

Tool center point ； Tool orientation smoothing ； Jerk control ； Five-axis machine tool

參考文獻

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