五軸CNC插補器設計與動態誤差分析;Five-Axis CNC Interpolator Design and Dynamic Error Analysis

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Please use this identifier to cite or link to this item: http://ccur.lib.ccu.edu.tw/handle/A095B0000Q/116

Title:	五軸CNC插補器設計與動態誤差分析;Five-Axis CNC Interpolator Design and Dynamic Error Analysis
Authors:	吳仕凱;WU, SHIH-KAI
Contributors:	機械工程系研究所
Keywords:	五軸工具機;速度規劃;刀具中心點;動態誤差;Five-axis machine tools;Feedrate planning;Tool Center Point (TCP);Dynamic error
Date:	2018
Issue Date:	2019-05-23 12:52:35 (UTC+8)
Publisher:	機械工程系研究所
Abstract:	為了達到先進製造的目標，五軸工具機是重要的加工技術之一，而電腦數值控制器是其中的核心技術，本論文所提出之五軸刀具中心點插補演算法可產生國際標準ISO 10791-6中的五軸檢測路徑以及多線段軌跡的高速插補命令，首先根據刀具中心點移動距離與機械驅動軸的最大速度來決定速度規劃中刀具中心點單線段的最大速度，並以刀具中心點與旋轉軸的路徑長度結合機械驅動軸的速度限制條件，推導轉角速度差公式，找出刀具中心點路徑上的轉角速度，接著使用S型加減速方法來規劃平滑之刀具中心點路徑與旋轉軸的進給率，最後利用動態模擬驗證轉角速度差法可大幅減少加工時間。同時本論文針對五軸量測路徑建立輪廓誤差模型，在五軸量測路徑中，分別將路徑插補命令代入伺服模型後，此模型可在五軸同動時準確預測動態誤差，穩態輪廓誤差模型(SSCE)在範例中展示三種特定的動態誤差行為:分別是單圓、雙圓以及平移誤差，並提出五軸伺服調整的方法，可以大幅改善由於各軸動態不匹配所導致的體積誤差，本論文所提出的方法已在實驗室之桌上型五軸雕刻機進行驗證，同樣可以有效的修正刀具中心點路徑之動態輪廓精度。此外，利用插補命令結合伺服系統的動態模型來進行擬驗證轉角速度差演算法的效能評估，動態模擬結果顯示除了可達到與商用控制器相似的輪廓精度外，並可有效改善加工時間。 In this paper, the five-axis tool center point (TCP) feedrate scheduling algorithm for measuring paths of ISO 10791-6 and linear multi-blocks trajectory are proposed to generate a high-speed interpolation command. First, the maximum speed in TCP single block segment is determined according to the segment displacement. The feedrate planning is constrained by axis velocity, acceleration and jerk on the machine tool. Each drive axes constraints and kinematical of the machine are employed to derive the five-axis corner velocity difference (FCVD) formulation. Next step, the S-shape Acceleration/Deceleration (Acc/Dec) profile is adapted to generate smoothing TCP and rotary axis feedrate in blocks. Finally, the FCVD method is demonstrated to substantially reduce the cycle time in dynamic simulation.Simultaneously, the TCP contour error model on five-axis measuring paths is derived. The error model can accurately estimate contour error during five-axis synchronized motions by substituting the commands of the measuring trajectory into the servo dynamics models. The steady state contour error (SSCE) model is demonstrated to illustrate three particular dynamic behaviors: the single-circle with amplitude modulation, double-circle effect and offset behavior. Furthermore, a servo tuning approach to achieve five-axis dynamic matching is utilized to improve contouring performance of the cutting trajectory. The contour errors caused by servo mismatch are reduced remarkably. Finally, experiments are conducted on a desktop five-axis engraving machine to verify the proposed methodology can improve dynamic contouring accuracy of the TCP significantly. Furthermore, the servo dynamic model of the five-axis machine is incorporated with the interpolator to evaluate the performances of the FCVD algorithm. The results is also shown that the FCVD has similar velocity characteristics as commercial controller. The FCVD has similar contour error as commercial controller, but it can achieve less machining time.
Appears in Collections:	[機械工程學系] 學位論文

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