本文關(guān)鍵詞： 數(shù)控加工仿真 刀具掃描體 STL模型 布爾運(yùn)算 效率優(yōu)化 空間分解 精度驗(yàn)證　出處：《浙江大學(xué)》2016年博士論文　論文類型：學(xué)位論文

【摘要】：精度和速度的權(quán)衡是數(shù)控加工仿真不可回避的矛盾問題�；赟TL模型的數(shù)控加工仿真方法具有仿真精度高且模型數(shù)據(jù)便于交換的優(yōu)點(diǎn),但是由于STL模型之間的布爾運(yùn)算計(jì)算復(fù)雜且計(jì)算量大,因此也存在著仿真速度慢的不足。為了在保證仿真精度的前提下提高仿真速度,本文提出并實(shí)現(xiàn)了基于STL模型的數(shù)控加工仿真方法,重點(diǎn)研究了仿真效率的優(yōu)化方法。本文研究內(nèi)容如下:刀具掃描體是數(shù)控加工仿真的前提,對切削過程的動(dòng)態(tài)仿真起著重要的作用。本文以包絡(luò)理論為基礎(chǔ),根據(jù)刀具的幾何特點(diǎn)和運(yùn)動(dòng)特點(diǎn),提出了一種結(jié)合插值法、離散法和二分查找法計(jì)算包絡(luò)點(diǎn)位置的方法,實(shí)現(xiàn)了對刀具掃描體的快速準(zhǔn)確建模。同時(shí),對刀具掃描體建模過程中可能出現(xiàn)的自相交問題,提出了預(yù)判與解決的方法。本文提出的刀具掃描體建模方法適用于任意形狀的回轉(zhuǎn)刀具,并且適用于多軸數(shù)控加工仿真。STL模型的布爾運(yùn)算是數(shù)控加工仿真的關(guān)鍵算法,切削過程的動(dòng)態(tài)仿真就是通過工件和刀具掃描體這兩個(gè)STL模型之間的連續(xù)布爾求差運(yùn)算實(shí)現(xiàn)的。為保證數(shù)控加工仿真的精度,本文實(shí)現(xiàn)了一種STL模型的精確布爾運(yùn)算算法,研究了算法中出現(xiàn)的三角面片共面、共邊和無效交線等幾何奇異性問題,提高了算法的可靠性。該算法由三角面片的相交性測試、相交三角形的區(qū)域剖分、相對位置關(guān)系測試等步驟組成。在基于STL模型的數(shù)控加工仿真中,影響仿真速度的關(guān)鍵因素是布爾運(yùn)算中的相交性測試。為了對相交性測試進(jìn)行優(yōu)化,本文綜合實(shí)體分割法和空間網(wǎng)格法的優(yōu)點(diǎn)將兩者結(jié)合使用。首先使用實(shí)體分割法將一個(gè)完整的工件分割為若干個(gè)子工件,通過包圍盒算法快速排除不可能與刀具掃描體相交的子工件。對于可能與刀具掃描體相交的子工件,采用空間網(wǎng)格法將相交三角面片的搜索范圍縮小到空間單元格內(nèi)部,從而減少了相交性測試的計(jì)算量并提高了數(shù)控加工仿真的效率。最后以注塑模具型芯件的加工仿真為例對這兩種方法的優(yōu)化效果做了測試,結(jié)果表明STL模型越復(fù)雜優(yōu)化效果越顯著。在研究刀具掃描體快速造型算法、STL模型布爾運(yùn)算算法以及相交性測試優(yōu)化算法的基礎(chǔ)上,實(shí)現(xiàn)了動(dòng)態(tài)切削仿真并對仿真結(jié)果進(jìn)行了幾何精度驗(yàn)證。幾何精度驗(yàn)證算法主要由采樣點(diǎn)計(jì)算和有向距離計(jì)算兩個(gè)步驟組成。通過幾何精度驗(yàn)證算法可以將仿真結(jié)果與設(shè)計(jì)模型進(jìn)行定量分析比較,從而檢驗(yàn)數(shù)控編程是否滿足精度要求。
[Abstract]:The tradeoff between precision and speed is an unavoidable contradiction in NC machining simulation. The NC machining simulation method based on STL model has the advantages of high simulation precision and easy exchange of model data. However, due to the complexity and complexity of the Boolean operations between STL models, there is also a lack of slow simulation speed. In this paper, the simulation method of NC machining based on STL model is put forward and realized, and the optimization method of simulation efficiency is studied emphatically. The contents of this paper are as follows: tool scanning is the premise of NC machining simulation. In this paper, based on envelope theory and according to the geometric and kinematic characteristics of cutting tools, a new method for calculating the position of envelope points is proposed, which combines interpolation method, discrete method and binary search method. At the same time, the self-intersection problem that may occur in the modeling process of tool scanning volume is realized. The method of tool scanning volume modeling proposed in this paper is suitable for any shape rotary tool, and the Boolean operation of multi-axis NC machining simulation .STL model is the key algorithm of NC machining simulation. The dynamic simulation of cutting process is realized by the continuous Boolean difference operation between the two STL models of workpiece and tool scanning. In order to ensure the accuracy of NC machining simulation, a precise Boolean algorithm of STL model is implemented in this paper. In this paper, the geometric singularity problems such as triangulated plane coplanar, common edge and invalid intersection are studied, and the reliability of the algorithm is improved. The algorithm is tested by the intersection of triangles, and the region of intersected triangles is divided. In the NC machining simulation based on STL model, the key factor affecting the simulation speed is the intersection test in Boolean operation. This paper combines the advantages of entity segmentation method and spatial grid method to combine the two methods. Firstly, a complete job is divided into several sub-jobs by using entity segmentation method. The bounding box algorithm is used to quickly eliminate the sub-workpieces that cannot intersect with the cutter scanning body. For the sub-workpieces that may intersect with the tool scanning volume, the search range of the intersected triangular slices is reduced to the inner of the spatial cells by the spatial grid method. Therefore, the calculation of intersecting test is reduced and the efficiency of NC machining simulation is improved. Finally, the optimization effect of these two methods is tested by taking the machining simulation of injection mould core parts as an example. The results show that the more complex the STL model is, the more significant the optimization effect is. The geometric precision verification algorithm is mainly composed of sampling point calculation and directed distance calculation. The geometric precision verification algorithm can be used to verify the geometric accuracy of the simulation. The results were compared quantitatively with the design model. In order to verify whether NC programming meets the accuracy requirements.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：TG659

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