本文選題：高階切觸 + 切觸階��； 參考：《北京理工大學(xué)》2015年碩士論文

【摘要】：自由曲面外觀精美、動(dòng)力學(xué)性能突出,在各行各業(yè)得到廣泛應(yīng)用。目前復(fù)雜自由曲面造型技術(shù)已經(jīng)相當(dāng)成熟,但其復(fù)雜的造型和高精度的要求對加工提出了難題。五軸聯(lián)動(dòng)加工是工業(yè)中復(fù)雜高性能零件高效加工的重要手段,能夠加工連續(xù)、平滑、復(fù)雜的自由曲面。由于其自由度的增加,導(dǎo)致加工過程中刀具姿態(tài)控制以及刀具路徑規(guī)劃復(fù)雜度提高,因此,在復(fù)雜自由曲面零件的五軸數(shù)控加工中,對刀具姿態(tài)調(diào)整以及刀具路徑規(guī)劃的研究具有重要的實(shí)際意義。本文分析了自由曲面加工中的幾何學(xué)原理,基于曲面高階切觸性質(zhì)提出二階切觸法,對曲面加工過程中的刀具姿態(tài)調(diào)整和刀具路徑規(guī)劃進(jìn)行研究,主要包括:(1)應(yīng)用微分幾何曲線論和曲面論,討論了曲面之間關(guān)系與曲面自身特性的聯(lián)系,針對曲面之間的相切接觸,引入切觸階的概念,研究了切觸階與曲面主曲率、法曲率的關(guān)系并將其應(yīng)用于刀具包絡(luò)曲面局部重建模型中。(2)基于曲面高階切觸性質(zhì)分析,從二次曲面與自由曲面的切觸特性出發(fā),建立回轉(zhuǎn)刀具加工自由曲面的局部幾何模型,計(jì)算出回轉(zhuǎn)刀具包絡(luò)面與自由曲面在某一法截面內(nèi)二階切觸時(shí)的刀軸矢量函數(shù)式,進(jìn)而推廣到切觸點(diǎn)鄰域內(nèi)任意法截面,得到刀具包絡(luò)面與自由曲面二階切觸時(shí)的刀軸傾角函數(shù),并解析求解出該狀態(tài)下的刀具姿態(tài)方程。(3)針對刀軸矢量函數(shù)表達(dá)式,選擇開闊參數(shù)凹曲面作為研究對象,并對其進(jìn)行仿真分析,得到各離散刀觸點(diǎn)處刀具包絡(luò)面與待加工自由曲面二階切觸時(shí)的曲率函數(shù)曲線,驗(yàn)證了刀軸傾角函數(shù)曲線在同一離散刀位下有公共交點(diǎn),并且在同一參數(shù)線上不同離散刀位處的刀軸傾角變化平穩(wěn),加工過程穩(wěn)定。(4)以加工行距最大為目標(biāo)優(yōu)化加工方向,將尋求加工方向的過程轉(zhuǎn)變?yōu)閷Υ庸ぷ杂汕孀钚≈髑史较虻钠ヅ溥^程。提出了等弓高誤差變步長算法,基于黃金分割法由區(qū)間逼近求取最大弓高誤差點(diǎn)參數(shù),并根據(jù)初始刀觸點(diǎn)與臨時(shí)離散刀觸點(diǎn)之間的曲率半徑關(guān)系,對最大實(shí)際弓高誤差進(jìn)行校核。(5)通過計(jì)算機(jī)數(shù)值模擬,以仿真結(jié)果驗(yàn)證了本論文所提算法的可行性及其可靠性,其后又通過實(shí)驗(yàn)分析,表明文中所建立的模型不僅能滿足加工表面精度的要求,并且能在很大程度上提高加工效率,具有實(shí)際的借鑒意義。
[Abstract]:The free-form surface has been widely used in various industries because of its fine appearance and outstanding dynamic performance. At present, the modeling technology of complex free-form surface has been quite mature, but its complex modeling and high precision requirements put forward a difficult problem for machining. Five-axis linkage machining is an important method for efficient machining of complex and high performance parts in industry. It can process continuous, smooth and complex free-form surfaces. Due to the increase of the degree of freedom, the tool attitude control and tool path planning complexity increase in the machining process. Therefore, in the five-axis NC machining of complex free-form surface parts, The research on tool posture adjustment and tool path planning is of great practical significance. In this paper, the geometric principle of free-form surface machining is analyzed. Based on the high-order contact property of surface, a second-order contact method is proposed to study the tool attitude adjustment and tool path planning in the process of surface machining. In this paper, the relation between the relationship between surfaces and their own characteristics is discussed. According to the tangent contact between surfaces, the concept of contact order is introduced, and the contact order and principal curvature of surfaces are studied. The relationship of normal curvature and its application in the local reconstruction model of tool enveloping surface. (2) based on the analysis of high order contact property of surface, the local geometric model of machining free surface with rotary tool is established based on the contact characteristics of Quadric and free surface. The vector function of cutter axis is calculated when the enveloping surface and free surface of rotary tool are in the second order contact of a certain normal section, which is extended to any normal section in the neighborhood of tangent contact. The cutter axis inclination function of the second order contact between the tool envelope and the free surface is obtained, and the tool attitude equation under this condition is solved analytically. (3) aiming at the expression of the cutter axis vector function, the open parameter concave surface is chosen as the research object. The curve of curvature function between the cutter envelope at the contact point of the discrete knife and the second order contact of the free-form surface is obtained, and the curve of the inclination function of the cutter axis has a common intersection point under the same discrete cutter position. At the same parameter line, the inclination of the cutter shaft at different discrete positions is stable, and the machining process is stable. 4) the maximum line spacing is the objective of optimizing the machining direction. The process of seeking the machining direction is transformed into the matching process of the minimum principal curvature direction of the machining free surface. A variable step algorithm for equal bow height error is proposed. Based on the golden section method, the maximum arch height error point parameters are obtained by interval approximation, and the curvature radius relationship between the initial cutter contact point and the temporary discrete knife contact point is also discussed. By computer simulation, the feasibility and reliability of the proposed algorithm are verified by computer simulation, and then the experimental analysis is carried out. It is shown that the model established in this paper can not only meet the requirements of machining surface precision, but also improve the machining efficiency to a great extent, which is of practical significance.
【學(xué)位授予單位】：北京理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TG659

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