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青島理工大學(xué)本科畢業(yè)設(shè)計(jì)（論文）說明書
附件1
機(jī)電一體化技術(shù)
機(jī)電一體化又稱機(jī)械電子學(xué)，英語稱為Mechatronics，它是由英文機(jī)械學(xué)Mechanics的前半部分與電子學(xué)Electronics的后半部分組合而成。機(jī)電一體化最早出現(xiàn)在1971年日本雜志《機(jī)械設(shè)計(jì)》的副刊上，隨著機(jī)電一體化技術(shù)的快速發(fā)展，機(jī)電一體化的概念被我們廣泛接受和普遍應(yīng)用。隨著計(jì)算機(jī)技術(shù)的迅猛發(fā)展和廣泛應(yīng)用,機(jī)電一體化技術(shù)獲得前所未有的發(fā)展?，F(xiàn)在的機(jī)電一體化技術(shù)，是機(jī)械和微電子技術(shù)緊密集合的一門技術(shù)，他的發(fā)展使冷冰冰的機(jī)器有了人性化，智能化。
機(jī)電一體化技術(shù)具體包括以下內(nèi)容：
（1） 機(jī)械技術(shù) 機(jī)械技術(shù)是機(jī)電一體化的基礎(chǔ)，機(jī)械技術(shù)的著眼點(diǎn)在于如何與機(jī)電一體化技術(shù)相適應(yīng)，利用其它高、新技術(shù)來更新概念，實(shí)現(xiàn)結(jié)構(gòu)上、材料上、性能上的變更，滿足減小重量、縮小體積、提高精度、提高剛度及改善性能的要求。在機(jī)電一體化系統(tǒng)制造過程中，經(jīng)典的機(jī)械理論與工藝應(yīng)借助于計(jì)算機(jī)輔助技術(shù)，同時(shí)采用人工智能與專家系統(tǒng)等，形成新一代的機(jī)械制造技術(shù)。
（2） 計(jì)算機(jī)與信息技術(shù)
其中信息交換、存取、運(yùn)算、判斷與決策、人工智能技術(shù)、專家系統(tǒng)技術(shù)、神經(jīng)網(wǎng)絡(luò)技術(shù)均屬于計(jì)算機(jī)信息處理技術(shù)。
（3） 系統(tǒng)技術(shù)
系統(tǒng)技術(shù)即以整體的概念組織應(yīng)用各種相關(guān)技術(shù)，從全局角度和系統(tǒng)目標(biāo)出發(fā)，將總體分解成相互關(guān)聯(lián)的若干功能單元，接口技術(shù)是系統(tǒng)技術(shù)中一個(gè)重要方面，它是實(shí)現(xiàn)系統(tǒng)各部分有機(jī)連接的保證。
（4） 自動(dòng)控制技術(shù)
其范圍很廣，在控制理論指導(dǎo)下，進(jìn)行系統(tǒng)設(shè)計(jì)，設(shè)計(jì)后的系統(tǒng)仿真，現(xiàn)場(chǎng)調(diào)試，控制技術(shù)包括如高精度定位控制、速度控制、自適應(yīng)控制、自診斷校正、補(bǔ)償、再現(xiàn)、檢索等。
（5） 傳感檢測(cè)技術(shù)
傳感檢測(cè)技術(shù)是系統(tǒng)的感受器官，是實(shí)現(xiàn)自動(dòng)控制、自動(dòng)調(diào)節(jié)的關(guān)鍵環(huán)節(jié)。其功能越強(qiáng)，系統(tǒng)的自動(dòng)化程序就越高?，F(xiàn)代工程要求傳感器能快速、精確地獲取信息并能經(jīng)受嚴(yán)酷環(huán)境的考驗(yàn)，它是機(jī)電一體化系統(tǒng)達(dá)到高水平的保證。
（6） 伺服傳動(dòng)技術(shù) 包括電動(dòng)、氣動(dòng)、液壓等各種類型的傳動(dòng)裝置，伺服系統(tǒng)是實(shí)現(xiàn)電信號(hào)到機(jī)械動(dòng)作的轉(zhuǎn)換裝置與部件、對(duì)系統(tǒng)的動(dòng)態(tài)性能、控制質(zhì)量和功能有決定性的影響。
機(jī)電一體化系統(tǒng)組成
1.機(jī)械本體 機(jī)械本體包括機(jī)架、機(jī)械連接、機(jī)械傳動(dòng)等，它是機(jī)電一體化的基礎(chǔ)，起著支撐系統(tǒng)中其他功能單元、傳遞運(yùn)動(dòng)和動(dòng)力的作用。與純粹的機(jī)械產(chǎn)品相比，機(jī)電一體化系統(tǒng)的技術(shù)性能得到提高、功能得到增強(qiáng)，這就要求機(jī)械本體在機(jī)械結(jié)構(gòu)、材料、加工工藝性以及幾何尺寸等方面能夠與之相適應(yīng)，具有高效、多功能、可靠和節(jié)能、小型、輕量、美觀的特點(diǎn)。
2.檢測(cè)傳感部分 檢測(cè)傳感部分包括各種傳感器及其信號(hào)檢測(cè)電路，其作用就是檢測(cè)機(jī)電一體化系統(tǒng)工作過程中本身和外界環(huán)境有關(guān)參量的變化，并將信息傳遞給電子控制單元，電子控制單元根據(jù)檢查到的信息向執(zhí)行器發(fā)出相應(yīng)的控制。
3.電子控制單元 電子控制單元又稱ECU（Electrical Control Unit ），是機(jī)電一體化系統(tǒng)的核心，負(fù)責(zé)將來自各傳感器的檢測(cè)信號(hào)和外部輸入命令進(jìn)行集中、存儲(chǔ)、計(jì)算、分析，根據(jù)信息處理結(jié)果，按照一定的程度和節(jié)奏發(fā)出相應(yīng)的指令，控制整個(gè)系統(tǒng)有目的地進(jìn)行。
4.執(zhí)行器 執(zhí)行器的作用是根據(jù)電子控制單元的指令驅(qū)動(dòng)機(jī)械部件的運(yùn)動(dòng)。執(zhí)行器是運(yùn)動(dòng)部件，通常采用電力驅(qū)動(dòng)、氣壓驅(qū)動(dòng)和液壓驅(qū)動(dòng)等幾種方式。
5.動(dòng)力源 動(dòng)力源是機(jī)電一體化產(chǎn)品能量供應(yīng)部分，其作用是按照系統(tǒng)控制要求向機(jī)械系統(tǒng)提供能量和動(dòng)力使系統(tǒng)正常運(yùn)行。提供能量的方式包括電能、氣能和液壓能，以電能為主。
機(jī)電一體化主要課程
機(jī)械方面：機(jī)械制圖，機(jī)械設(shè)計(jì)，工程材料，工程力學(xué)，數(shù)控編程技術(shù)，autoCAD，Mastercam軟件，C#
電工方面：可編程控制器PLC，單片機(jī)，自動(dòng)控制原理，數(shù)字電路，電工電子
實(shí)習(xí)課程：電力拖動(dòng)，PLC，單片機(jī)，鉗工，普通車、銑、刨床，數(shù)控車、銑，加工中心
本專業(yè)的培養(yǎng)目標(biāo)
本專業(yè)培養(yǎng)德、智、體、美全面發(fā)展，具有創(chuàng)業(yè)、創(chuàng)新精神和良好職業(yè)道德的高等專門人才，掌握機(jī)械技術(shù)和電氣技術(shù)的基礎(chǔ)理論和專業(yè)知識(shí)；具備相應(yīng)實(shí)踐技能以及較強(qiáng)的實(shí)際工作能力，熟練進(jìn)行機(jī)電一體化產(chǎn)品和設(shè)備的應(yīng)用、維護(hù)、安裝、調(diào)試、銷售及管理的第一線高等技術(shù)應(yīng)用型人才。
本專業(yè)職業(yè)面向
機(jī)電一體化專業(yè)是一個(gè)寬口徑專業(yè)，適應(yīng)范圍很廣，學(xué)生在校期間除學(xué)習(xí)各種機(jī)械、電工電子、計(jì)算機(jī)技術(shù)、控制技術(shù)、檢測(cè)傳感等理論知識(shí)外，還將參加各種技能培訓(xùn)和國(guó)家職業(yè)資格證書考試，充分體現(xiàn)重視技能培養(yǎng)的特點(diǎn)。學(xué)生畢業(yè)后主要面向珠江三角洲各企業(yè)、公司，從事加工制造業(yè)，家電生產(chǎn)和售后服務(wù)，數(shù)控加工機(jī)床設(shè)備使用維護(hù)，物業(yè)自動(dòng)化管理系統(tǒng)，機(jī)電產(chǎn)品設(shè)計(jì)、生產(chǎn)、改造、技術(shù)支持，以及機(jī)電設(shè)備的安裝、調(diào)試、維護(hù)、銷售、經(jīng)營(yíng)管理等等。
1、主要就業(yè)崗位：機(jī)電一體化設(shè)備的安裝、調(diào)試、維修、銷售及管理；普通機(jī)床的數(shù)控化改裝等。
2、次要就業(yè)崗位：機(jī)電一體化產(chǎn)品的設(shè)計(jì)、生產(chǎn)、改造、技術(shù)服務(wù)等
傾斜表面移動(dòng)熱源模型
在磨削加工中，大部分產(chǎn)生的能量會(huì)轉(zhuǎn)換成熱量。磨削加工區(qū)的高溫對(duì)工件表面質(zhì)量、磨削精確度、磨削效率和砂輪的磨削磨削表現(xiàn)都有很重要的影響。因此對(duì)磨削熱方面的就顯得相當(dāng)重要并且在多年來一直作為磨削加工中的重要研究課題。
1 引言
對(duì)于磨削溫度的計(jì)算，目前大多數(shù)熱源模型都將熱源平面假設(shè)為以速度v沿半無限體移動(dòng)，即忽略磨削深度并將磨削上下表面當(dāng)作同一表面。熱源平面與移動(dòng)方向平行（圖1，=0）。對(duì)于普通的淺磨來說，這種假設(shè)很好地接近實(shí)際情況的，但是對(duì)于深磨的情況，例如緩進(jìn)給磨削和高效深切磨削，磨削深度大約能達(dá)到10毫米。這種圖1(b)所示的簡(jiǎn)化的熱量轉(zhuǎn)移情況表明熱源平面與它的移動(dòng)方向之間存在一個(gè)傾斜角，傾斜平面熱以速度v轉(zhuǎn)換和預(yù)熱材料直接在前面的這個(gè)平面在不斷消除。很明顯對(duì)于深磨情況上述的假設(shè)需要被修改且磨削深度、傾斜角應(yīng)該被考慮。
圖1 熱源平面和它在深磨中的運(yùn)動(dòng)
對(duì)于垂直磨削的磨削區(qū)溫度的研究也需要考慮熱源平面的傾斜移動(dòng)。有一個(gè)比較好的的方法是通過假設(shè)一個(gè)統(tǒng)一的溫度帶來表現(xiàn)磨削區(qū)熱源平面以磨削速度在加工表面移動(dòng)，該平面與有一個(gè)傾斜角，表面被當(dāng)作半無限體。Jaeger的解決方案是直接用在剪切面和是與溫度有關(guān)的解決方案，在切屑方面。雖然一個(gè)比較明確和直接的解決辦法是源自與假設(shè)，Dawson和Malkin的求解方法仍然存在一些值得商榷方面，由于相對(duì)過度簡(jiǎn)化指出的那樣。在現(xiàn)實(shí)中熱源對(duì)剪切機(jī)不會(huì)移動(dòng)，沿剪切面，但動(dòng)作與切削速度對(duì)材料在前面的剪切機(jī)，一部分熱量進(jìn)入到工件是不斷帶走的物質(zhì)拆除之前，它可以轉(zhuǎn)移到該地區(qū)下方的前沿。
簡(jiǎn)化的解決方案，與直接利用Jaeger理論對(duì)剪切面，缺乏理論的合理性，雖然也是必要的精度，特別是在較大的剪切角度和更高的切削速度時(shí)。Rapier的方法則解決了這個(gè)問題與數(shù)值計(jì)算方法，這是一種基于一維穩(wěn)定傳熱移動(dòng)無限熱平面均勻的溫度分布在一個(gè)無限固體的方法;問題是處理在這方面，不僅速度垂直切變，平面不可或缺的作用，對(duì)熱轉(zhuǎn)移在剪切帶。為案件高切削速度，劍桿織機(jī)的解決方案是一個(gè)較好的逼近，但未能得到有效的，當(dāng)磨削情況有較低的切削速度和較小的剪切角時(shí)不適合的分析磨削區(qū)溫度。
在此基礎(chǔ)上的基本微分方程穩(wěn)定的傳熱和統(tǒng)一熱流的假設(shè)，Dawson和Malkin解決了傳熱問題的斜平面移動(dòng)源的有限元方法，并取得了一系列的數(shù)值解，根據(jù)不同的熱條件。熱兩方面正交切削和緩進(jìn)給磨削進(jìn)行了分析與這些解決方案。與統(tǒng)一的熱流所承擔(dān)的熱源平面，最高量綱溫升在于大約在磨削尾區(qū)，這是并非如此，在普通和緩進(jìn)給磨削中。雖然整體的有限元分析應(yīng)提供最準(zhǔn)確的分析估計(jì)的溫度所產(chǎn)生的（即前面所提到的Dawson和Malkin的方法），這種方法是相當(dāng)復(fù)雜的，必須反復(fù)為每一個(gè)情況都考慮。他們的結(jié)果還出現(xiàn)一些分歧，與其他研究者的分析方法仍然是一個(gè)直接的方法由于其方便的利用和明確的理論意義，如果一個(gè)理性的解析解可以得到。
上面所提到的熱傳遞的熱分析中存在的問題在本論文中得到了比較好的解決。本論文中建立了三中相關(guān)聯(lián)的熱傳遞熱源模型，其中平均熱源模型和三角形熱源模型都分別進(jìn)行了一維或二維熱傳遞分析。這三種熱源模型都將熱原平面的傾斜移動(dòng)考慮在內(nèi)，這對(duì)于研究高效深切磨削和大傾斜角熱源平面都有很重要的意義。從這些熱源模型中得到的溫升求解方案，在高效深切磨削中也做了研究。該論文中提出的熱源模型可以用作對(duì)深切磨削和垂直磨削的問題進(jìn)行分析，其中對(duì)垂直磨削的分析只是簡(jiǎn)短的討論了一下。
2 一維傾斜移動(dòng)熱源模型
2.1統(tǒng)一熱流量模型
直角坐標(biāo)系如圖2所示，引起AB面溫度升高的熱量在工作平面中，來自同一個(gè)熱源，熱源在臨近的以速度v移動(dòng)的平面上，熱源沿z軸一維傳遞。坐標(biāo)值z(mì)當(dāng)平面靠近平面AB時(shí)減小，熱量逐漸由B傳遞到A，直到平面與平面AB重合。
平面與平面AB近似取作相等，AB==L，L是磨削弧的長(zhǎng)度。熱源平面在平面AB上的作用時(shí)間。
在熱量傳遞的一瞬間，平面?zhèn)鬟f的熱量為，是熱源平面的平均熱流量，被當(dāng)作半無限體的平面，平面AB上點(diǎn)E(x,0)的溫升即由和點(diǎn)E的座標(biāo)共同決定，根據(jù)半無限體表面瞬態(tài)熱源的鏡像原理，即可計(jì)算出該熱量值[14,15]：
(1)
其中：，，（見圖2），分別是比熱容，密度，熱分散率和熱傳導(dǎo)率。點(diǎn)E從熱源面開始受熱的時(shí)間是：，。從到時(shí)間內(nèi)，E點(diǎn)的溫升為：
(2)
求解得：
圖2 一維統(tǒng)一熱流量熱源模型
(3)
方程（3）的無量綱形式為：
(4)
其中：
，，
2.2 三角形熱源模型
沿磨削加工區(qū)，切屑的厚度并不一致，在磨削加工區(qū)的前沿厚度最大而在磨削加工區(qū)的尾部磨屑厚度接近零，所以三角形熱源模型更合理。在熱源平面上假設(shè)一個(gè)三角形熱源模型，如圖3所示。那么在時(shí)刻內(nèi)（），在點(diǎn)E(x,0)上來自熱源平面的熱量是，這一時(shí)刻至的時(shí)間間隔等于。
點(diǎn)E靠近半無限體上的熱源平面的溫升受到熱發(fā)散率的影響，也可以用和方程(1)類似的方法計(jì)算這個(gè)溫升，即：
(5)
在時(shí)間內(nèi)E點(diǎn)的溫升為：
(6)
該方程可以通過以下幾步進(jìn)行積分求解：
(7)
方程(6)的無量綱形式為：
(8)
圖3 一維三角形熱源模型
3 二維傾斜移動(dòng)熱源模型
處理二維熱傳遞問題需要通過幾個(gè)步驟來求解。首先要認(rèn)為在y方向上有一條無限長(zhǎng)的熱源線，且其在無限體內(nèi)沿x軸方向上的熱流率q和速度為，有一點(diǎn)M(x,y,z)在固體內(nèi)以速度沿z軸移動(dòng)(見圖4)。
圖4 在無限體中的無數(shù)條無限熱源線
在時(shí)刻，由熱源平面的熱流量引起單位點(diǎn)M(x,y,z)的溫升（這與y坐標(biāo)軸無關(guān)）可以根據(jù)在無限體內(nèi)的無限熱源線方程式求解：
(9)
變量間的關(guān)系如圖4所示，。移動(dòng)坐標(biāo)系采用：，。從時(shí)刻到時(shí)間內(nèi)，M點(diǎn)的溫升可以根據(jù)方程(10)來計(jì)算，即：
(10)
求解得：
(11)
其中：
當(dāng)時(shí)，可近似認(rèn)為
傾斜平面AB的熱源可視作無數(shù)條沿y方向的熱源線，且移動(dòng)坐標(biāo)系以速度移動(dòng)，如圖5所示：
圖5 二維統(tǒng)一熱流量熱源模型
每條熱源線的移動(dòng)速度為，即，。在單獨(dú)一條熱源線的作用下，點(diǎn)的溫升可以用等式(11)附加鏡像熱源法則來計(jì)算，即等式(12)：
(12)
在全部熱源平面作用下點(diǎn)的溫升如下用等式(13)來計(jì)算：
(13)
在熱源平面上：
(14)
求解得：
(15)
其中：
表面溫升的無量綱形式為：
(16)
當(dāng)，時(shí)：
(17)
這與Jaeger的求解方法一致，即Jaeger的方法是傾斜移動(dòng)熱源模型的一種特殊形式，這就進(jìn)一步證明了上面的假設(shè)與得出的結(jié)論的正確性。
附件2
Mechatronics
Electrical machinery and electronics, also known as the integration of science, English as Mechatronics, it is by English mechanics of the first half of Mechanics and Electronics of the latter part of a combination of Electronics. Mechatronics 1971, first appeared in Japanese magazine, "Machine Design" on the supplement, with the mechanical-electrical integration of the rapid development of technology, electromechanical integration, the concept was widely accepted and we have universal application. With the rapid development of computer technology and extensive application of mechatronics technology unprecedented development. Mechatronics present technology, mechanical and micro-electronics technology is closely a set of technologies, the development of his machine has been cold humane, intelligent.
Specific mechanical and electrical integration technologies, including the following:
(1) mechanical engineering machinery and technology is the basis of mechatronics, mechanical technology, focused on how to adapt to mechanical and electrical integration technologies, the use of other high and new technology to update the concept, the realization of the structure, materials, the performance changes to meet the needs to reduce weight, reduce the size and improve accuracy, increase the stiffness and improving the performance requirements. Mechatronic systems in the manufacturing process, the classical theory and technology of mechanical computer-aided technology should help, while the use of artificial intelligence and expert systems, the formation of a new generation of mechanical manufacturing technology.
(2) Computer and Information Technology
Which information exchange, access, computing, judge and decision-making, artificial intelligence techniques, expert system technology, neural networks are computer information processing technology.
(3) System Technology
System technology that is the concept of the overall application of related technology organizations, from the perspective of the overall objectives and systems will be interconnected into the overall number of functional units, system interface technology is an important aspect of technology, it is an organic part of the realization of system guarantee connectivity.
(4) Automatic Control Technology
Its scope is broad, under the guidance of the control theory for system design, design of system simulation, live debugging, control technology include, for example, high-precision positioning control, speed control, adaptive control, self-diagnosis calibration, compensation, reproduction, retrieval, etc. .
(5) Sensor detection technology
Sensor detection technology is the feeling of organ systems, is to achieve automatic control, the key to automatic adjustment. The stronger its functions, the system the higher the automation process. Engineering requirements of modern sensors can be fast and accurate access to information and are able to withstand the harsh environment of the test, it is the mechanical-electrical integration systems to achieve a high level of assurance.
(6) Servo-drive technology, including electric, pneumatic, hydraulic and other types of actuators, servo system is a signal to the mechanical action to achieve the conversion devices and components, the dynamic performance of the system, control the quality and features have a decisive impact.
Mechatronics system
1. Machinery ontology ontology including mechanical rack, mechanical connections, such as mechanical transmission, which is the basis of mechanical-electrical integration, play a support system of other functional units, transmission of the role of movement and power. And compared to purely mechanical products, electrical and mechanical systems integration technology to improve performance, enhanced functionality, which requires mechanical ontology in the mechanical structure, materials, processing technology, as well as the areas of geometry to adapt, with high efficiency, multi-functional, reliable and energy-saving, small, lightweight, aesthetically pleasing characteristics.
2. Detection sensor detecting sensor part includes a variety of sensors and signal detection circuit, and its function is to detect the process of mechatronic systems in the work itself and the external environment changes in the relevant parameters and information to the electronic control unit, electronic control unit checks the information in accordance with the actuator to the corresponding control issue.
3. Electronic Control Unit, also known as electronic control unit ECU (Electrical Control Unit), is the core of Mechatronic Systems, responsible for testing the sensor from the external input signal and centralized command, storage, computing, analysis, information processing based on the results of according to a certain extent and pace of the instructions issued to control the destination for the entire system.
4. Executor's role in the implementation of electronic control unit in accordance with the order-driven movement of mechanical components. Implementation is moving parts, usually electric, pneumatic and hydraulic drive, such as driving a number of ways.
5. The power source power source is a mechanical-electrical integration products part of the energy supply, the role of system control in accordance with the requirements of mechanical systems to provide energy and power system normal operation. Way to provide energy, including electricity, gas, energy and hydraulic energy, mainly electricity.
Main Courses Mechatronics
Mechanical aspects: mechanical drawing, mechanical design, engineering materials, engineering mechanics, numerical control programming techniques, autoCAD, Mastercam software, C #
Electrical connection: Programmable Logic Controller PLC, MCU, Automatic Control Theory, Digital Circuits, Electrical and Electronic
Internship Program: Power Drive, PLC, MCU, fitter, ordinary cars, milling, planer, NC cars, milling, machining center
The professional training objectives
Professional training of the moral, intellectual, physical, and aesthetic development, entrepreneurial, innovative spirit and the high professional ethics expertise, master mechanical technology and electrical technology, basic theory and professional knowledge; have the appropriate practical skills, as well as strong practical work the ability to carry out skilled mechanical and electrical integration products and equipment, maintenance, installation, commissioning, sales and management of front-line personnel in high technology applications.
The professional career-oriented
Mechatronics is a professional, to adapt to a wide range of students in school during the study in addition to a variety of mechanical, electrical electronics, computer technology, control technology, sensor detection, such as theory of knowledge, will also participate in a variety of skills training and National Vocational Qualification Certificate Examination, fully embodies the characteristics of attention to skills development. Students graduated from the Pearl River Delta will be mainly oriented company engaged in processing and manufacturing, household appliances production and after-sales service, the use of CNC machine tool equipment maintenance, property management system for automation, electrical and mechanical product design, production, transformation, technical support, as well as electrical and mechanical equipment installation, commissioning, maintenance, sales, management and so on.
1, the main jobs: electromechanical integration equipment, installation, commissioning, maintenance, sales and management; general machine tools, such as modification of the NC.
2, secondary jobs: mechatronics product design, production, transformation, and other technical services
Analytical Thermal Models of Oblique Moving Heat Source for Deep Grindingand Cutting
Author:Professor G. Q. Cai, School of Mechanical Engineering and Automation, Northeastern University
Three related analytical thermal models of plane heat source moving obliquely along the surface of a semi-infinite solid are presented. The temperature distribution of grinding zone under deep-cut conditions is investigated with these models. It is proposed that the oblique angle of the heat source plane to its moving direction has an essential influence on the grinding zone temperature rise and its distribution of high efficiency deep grinding(HEDG). Compared with that in creep-feed grinding, HEDG has a different form of heat flux distribution in grinding zone and should be treated with different thermal models. The temperature distribution at the shear zone of orthogonal cutting is also briefly discussed with the thermal models. The models developed in the paper provide a more rational and integrated analytical basis for dealing with the heat transfer problems of inclined moving heat sources.
1 Introduction
In grinding, most of the energy dissipated in the process is converted to heat. Elevated temperatures generated at the grinding zone have essential influences on the surface quality, grinding precision and efficiency, and also on the performance of the grinding wheel. Investigation into the thermal aspects of grinding is thus of considerable importance and has been a subject of much research for many years.
For the calculation of grinding temperatures, most thermal models developed up to now handle the conditions in which the heat source plane is assumed to move with feed velocity v along the surface of a semi-infinite solid, i.e., ignore the existence of grinding depth and take the ground and unground surfaces as the same one; the source plane is thus parallel to its moving direction(Fig.1: =0) For ordinary shallow-cut grinding conditions, the assumption above is a good approximation to reality,but for those with quite deep cuts, e.g., in creep-feed grinding and high efficiency deep grindingHEDG, the depth of cut can reach the level of some 10 mm. The simplified heat transfer condition in Fig.(1)b shows that the heat source plane has an oblique angle to its moving direction, the oblique heat plane translates with velocity v and the preheated materials directly in front of the plane are continually removed. It is obvious that for the heat transfer solution under deep-cut conditions the above assumption should be modified and the effects of depth of cut and oblique angle should be taken into account.
The analysis on the shear zone temperature of orthogonal cutting also involves the oblique moving heat source problems. The well known method simplifies the solution by assuming that a uniform heat band presenting the shearing heat source moves with shearing velocity on the shear plane, which has an oblique shear angle to the cutting direction and is taken as the surface of a semi-infinite solid. Jaeger’s solution is then directly used on the shear plane and is related to temperature solution at chip side. Although a relatively clear and direct solution is derived with the assumption, there still exists some questionable aspects due to the relative excessive simplifications, as pointed out by Dawson and Malkin.In reality the heat source on the shear plane does not move along the shear plane but moves with cutting speed towards the material in front of the shear plane, a part of the heat entering to workpiece is continually taken away by the material removed just before it could transfer to the area beneath the cutting edge. The simplified solution with direct use of Jaeger’s theory on the shear plane thus lacks the theoretical rationality and also the necessary precision, especially in the case of larger shear angle and higher cutting speed. Rapier solved the problem with a numerical method, which is based on the one-dimensional stable heat transfer of a moving infinite heat plane with uniform temperature distribution in an infinite solid; the problem is handled in that only the velocity perpendicular to the shear plane has an essential effect on the thermal transfer at shear zone. For the case of high cutting speed, Rapier’s solution is a better approximation, but fails to be valid in the case of lower cutting speed and smaller shear angle and is also not suited for the analysis of grinding zone temperatures.
Based on the basic differential equation of stable heat transfer and the uniform heat flux assumption, Dawson and Malkin solved the heat transfer problem of oblique moving plane source with finite element method and obtained a series of numerical solutions under diverse thermal conditions. The thermal aspects of both orthogonal cutting and creep-feed grinding were analyzed with these solutions. With the uniform heat flux assumed on the source plane, the maximum dimensionless temperature rise lies approximately at the tail of the grinding zone, which is not the case in ordinary and creep-feed grinding. Although an overall finite element analysis should provide the most accurate analytical estimation of the temperature generated,(as mentioned by Dawson and Malkin) such a method is quite complex and must be repeated for each case at hand. Their results also show some differences with other authors. The analytical approach is still a straightforward way due to its convenience of utilization and clear theoretical meaning if a rational analytical solution can be derived.The heat transfer problem mentioned above is solved in this paper with analytical methods. Three related thermal models are developed in which both uniform and triangular heat flux distribution are respectively considered with the approach of one or two dimensional heat transfer analysis. All the three models take account of the oblique movement of the heat source plane, which is of particular importance for the conditions of high moving speed and large oblique angle of the heat source plane. With the solutions gained from the models the temperature and heat flux distribution at the grinding zone of HEDG is investigated. The models proposed in this paper can be used for the analysis of heat transfer problems of both deep-cut grinding and orthogonal cutting; the latter is briefly discussed.
2 One-Dimensional Heat Transfer Models of Oblique Moving Heat Source
2.1 Uniform Heat Flux Model.
The coordinate system is shown in Fig.2.The heat causing the temperature rise of plane AB in the workpiece comes from the uniform heat source on the vicinal surface plane which moves with velocity v and