立柱移動(dòng)式MK7125精密數(shù)控平面磨床橫向進(jìn)給和縱向進(jìn)給機(jī)構(gòu)及床身設(shè)計(jì)【含CAD圖紙】

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湖 南 科 技 大 學(xué) 畢業(yè)設(shè)計(jì)（論文）任務(wù)書 機(jī)電工程 學(xué)院 機(jī)械設(shè)計(jì)制造 系（教研室） 系（教研室）主任: 康輝民 （簽名） 2015 年 3 月 1 日 學(xué)生姓名: 張志強(qiáng) 學(xué)號: 1003010324 專業(yè): 機(jī)械設(shè)計(jì)制造及其自動(dòng)化 1 設(shè)計(jì)（論文）題目及專題： 立柱移動(dòng)式MK7125精密數(shù)控平面磨床橫向進(jìn)給和縱向進(jìn) 給機(jī)構(gòu)及床身設(shè)計(jì) 2 學(xué)生設(shè)計(jì)（論文）時(shí)間：自 2015 年 3 月17 日開始至 2015 年 5 月 25日止 3 設(shè)計(jì)（論文）所用資源和參考資料： [1]易紅.數(shù)控技術(shù).北京:機(jī)械工業(yè)出版社,2005 [2]張建民等編著.機(jī)電一體化系統(tǒng)設(shè)計(jì).北京:高等教育出版社,2010 [3]文懷心,夏田數(shù)控機(jī)床系統(tǒng)設(shè)計(jì).北京:化學(xué)工業(yè)出版社,2005 [4]李伯民,趙波主編.現(xiàn)代磨削技術(shù).北京:機(jī)械工業(yè)出版社,2003 [5]關(guān)慧貞、馮辛安等編著.機(jī)械制造裝備設(shè)計(jì).北京：機(jī)械工業(yè)出版社,2010 [6]卜云峰.機(jī)械工程及自動(dòng)化簡明設(shè)計(jì)手冊.北京:機(jī)械工業(yè)出版社,2001 [7]聞邦春主編.機(jī)械工程及自動(dòng)化簡明設(shè)計(jì)手冊.北京:機(jī)械工業(yè)出版社,2010 [8]姚峻.CIMT20033平面磨床展品評述.精密制造與自動(dòng)化,2003(3):14 ~18 [9]牛志斌.韋剛主編. 數(shù)控磨床技術(shù)應(yīng)用研究. 北京:機(jī)械工業(yè)出版社,2011 [10] 夏長鳳. 基于SINUMERIK 802D 的數(shù)控平面磨床電氣控制系統(tǒng).機(jī)械工程與 自動(dòng)化，2010（6）：178-180 4 設(shè)計(jì)（論文）應(yīng)完成的主要內(nèi)容： 1.磨床的總體布局設(shè)計(jì)； 2.立柱橫向進(jìn)給機(jī)構(gòu)設(shè)計(jì)，伺服電機(jī)和滾珠絲杠副設(shè)計(jì)計(jì)算，繪制橫向進(jìn)給機(jī)構(gòu)的機(jī)械結(jié)構(gòu)裝配圖；繪制相關(guān)零件圖； 3.工作臺(tái)縱向進(jìn)給機(jī)構(gòu)設(shè)計(jì)，繪制縱向進(jìn)給機(jī)構(gòu)機(jī)械結(jié)構(gòu)裝配圖及相關(guān)零件圖； 4.磨床床身的設(shè)計(jì)，繪制床身零件圖； 5.磨床數(shù)控系統(tǒng)的設(shè)計(jì)與選用； 6.翻譯指定的英文專業(yè)文獻(xiàn)； 7.撰寫畢業(yè)設(shè)計(jì)論文（說明書）。 5 提交設(shè)計(jì)（論文）形式（設(shè)計(jì)說明與圖紙或論文等）及要求： 圖紙工作總量折合A0圖紙3張以上，畢業(yè)設(shè)計(jì)論文字?jǐn)?shù)不少于1.5萬字，參考文獻(xiàn)至少15篇以上 6 發(fā)題時(shí)間： 年 月 日 指導(dǎo)教師： 鄧朝暉 （簽名） 學(xué) 生： 張志強(qiáng) （簽名） 湖 南 科 技 大 學(xué) 畢 業(yè) 設(shè) 計(jì)（ 論 文 ） 題目 立柱移動(dòng)式MK7125精密數(shù)控平面磨床橫向進(jìn)給和縱向進(jìn)給機(jī)構(gòu)及床身設(shè)計(jì) 作者 張志強(qiáng) 學(xué)院 機(jī)電工程學(xué)院 專業(yè) 機(jī)械設(shè)計(jì)制造及其自動(dòng)化 學(xué)號 1003010324 指導(dǎo)教師 鄧朝暉 二〇〇五年 六月三日 摘 要 數(shù)控平面磨床已經(jīng)向著精密化智能化復(fù)合化方向發(fā)展，精密平面磨床是重要的制造裝備，對于國家的制造業(yè)發(fā)展具有十分重要的意義。本畢業(yè)設(shè)計(jì)課題是設(shè)計(jì)一臺(tái)精密數(shù)控平面磨床，能用砂輪周邊磨削各類平面，可以加工各種難加工材料平面。 首先通過對國內(nèi)外平面磨床的發(fā)展現(xiàn)狀進(jìn)行論述，指出我國與國外在平面磨床發(fā)展水平的差距，突顯平面磨床研究的意義，引出課題。然后對當(dāng)前磨床布局的介紹，確定設(shè)計(jì)中磨床的總體布局。第三章從計(jì)算磨削力開始進(jìn)行磨床砂輪架的設(shè)計(jì)計(jì)算。接著進(jìn)行垂直進(jìn)給機(jī)構(gòu)的設(shè)計(jì)計(jì)算，完成之后設(shè)計(jì)立柱并選用合適的磨床數(shù)控系統(tǒng)。最后對設(shè)計(jì)結(jié)論進(jìn)行總結(jié)，并列出了本次設(shè)計(jì)中參考的文獻(xiàn)資料，末尾是對在設(shè)計(jì)中提供幫助的人的致謝。 關(guān)鍵詞：數(shù)控平面磨床；橫向進(jìn)給機(jī)構(gòu)；垂直進(jìn)給機(jī)構(gòu)；數(shù)控系統(tǒng)；床身 Abstract NC plane grinder has towards precision intelligent composite development,precision surface grinder is an important equipment manufacturing for manufacture industry. The graduation design topic is the design of a precision NC grinding machine, the periphery of the grinding wheel can use all kinds of plane, can process all kinds of difficult to machining materials. Firstly, the development situation of domestic and foreign plane grinder is discussed, pointed out that China and abroad on surface grinding machinedevelopment gap, highlighting the surface grinder research significance, present the topic. And then the current layout of the grinder, determine the overall layoutdesign of grinder. The third chapter is calculated from the design calculation togrinding wheel grinding force. Then the design and calculation of vertical feed mechanism, after the completion of design of column and select the appropriatenumerical control system of grinder. The design result are summarized, and listed the reference design,thanks to people who gave help at the end of the essay. Keywords: NC plane grinder; grinding wheel; the vertical feed mechanism; numerical control system 湖南科技大學(xué)本科生畢業(yè)設(shè)計(jì)（論文） 目 錄 第一章 前 言 - 3 - 1.1 課題背景 - 3 - 1.2 國內(nèi)外數(shù)控平面磨床的發(fā)展?fàn)顩r - 4 - 1.2.1 國內(nèi)數(shù)控平面磨床的發(fā)展?fàn)顩r - 4 - 1.2.2 國外數(shù)控平面磨床的發(fā)展?fàn)顩r - 5 - 1.3 課題研究的意義 - 7 - 1.4 課題研究內(nèi)容和方法 - 7 - 1.4.1 課題的研究內(nèi)容 - 7 - 1.4.2 完成設(shè)計(jì)課題的方法 - 8 - 1.5 設(shè)計(jì)的主要技術(shù)參數(shù) - 9 - 第二章 總體布局設(shè)計(jì) - 10 - 2.1 運(yùn)動(dòng)形式的設(shè)計(jì) - 10 - 2.2 機(jī)床的布局方案 - 11 - 第三章 縱向及橫向進(jìn)給機(jī)構(gòu)的設(shè)計(jì) - 12 - 3.1 進(jìn)給系統(tǒng)應(yīng)滿足的要求 - 12 - 3.2 磨削力的計(jì)算 - 12 - 3.2.1 磨削力力學(xué)模型的建立 - 12 - 3.3滾珠絲杠副的設(shè)計(jì)步驟圖 - 14 - 3.4 縱向滾珠絲杠的計(jì)算及伺服電機(jī)的選擇 - 14 - 3.4.1 滾珠絲杠副導(dǎo)程的確定 - 14 - 3.4.2 滾珠絲杠副軸向力的計(jì)算 - 16 - 3.4.3 滾珠絲杠副當(dāng)量載荷及當(dāng)量轉(zhuǎn)速的計(jì)算 - 16 - 3.4.4 確定滾珠絲杠副的預(yù)期額定動(dòng)載荷 - 18 - 3.4.5 按精度要求確定滾珠絲杠副的最小螺紋底徑 - 19 - 3.4.6 確定滾珠絲杠副的螺母代號及規(guī)格代號 - 19 - 3.4.7 滾珠絲杠副預(yù)緊力的計(jì)算 - 20 - 3.4.8 對預(yù)拉伸滾珠絲杠行程補(bǔ)償值C和預(yù)拉伸力Ft的計(jì)算 - 20 - 3.4.9 滾珠絲杠副軸承規(guī)格型號的選擇 - 20 - 3.4.10 滾珠絲杠副工作圖的設(shè)計(jì) - 21 - 3.4.11 滾珠絲杠副驅(qū)動(dòng)電機(jī)的選擇 - 22 - 3.4.12傳動(dòng)系統(tǒng)剛度的計(jì)算 - 26 - 3.4.13 傳動(dòng)系統(tǒng)剛度的校核及滾珠絲杠副精度的選擇 - 27 - 3.4.14 滾珠絲杠副臨界壓縮載荷的校驗(yàn) - 28 - 3.4.15 滾珠絲杠副極限轉(zhuǎn)速校驗(yàn) - 29 - 3.4.16 滾珠絲杠副值校驗(yàn) - 29 - 3.4.17 基本軸向額定靜載荷校核 - 29 - 3.4.18 聯(lián)軸器的選擇 - 30 - 3.5 滾珠絲杠副設(shè)計(jì)使用中應(yīng)注意的問題 - 31 - 3.6 導(dǎo)軌的設(shè)計(jì) - 31 - 3.6.1 導(dǎo)軌應(yīng)滿足的要求 - 31 - 3.6.2 導(dǎo)軌的具體設(shè)計(jì) - 32 - 3.7 縱向進(jìn)給機(jī)構(gòu)的設(shè)計(jì) - 34 - 第四章 磨床床身的設(shè)計(jì) - 35 - 4.1?床身應(yīng)滿足的要求 - 35 - 4.2?床身的設(shè)計(jì) - 35 - 4.2.1 床身材料的選擇 - 35 - 4.2.2?床身壁厚的確定 - 37 - 第五章 數(shù)控系統(tǒng)的選用 - 38 - 5.1 數(shù)控系統(tǒng)的概述 - 38 - 5.2 數(shù)控系統(tǒng)的選用 - 38 - 第六章 設(shè)計(jì)結(jié)論 - 40 - - 1 - Grinding-Some observations For the production of finished components of desired shape,size and accuracy, machining is the commonly used manufacturing process.Machining process involves the usage of single or multiple point cutting tools to remove the unwanted materials form the stock in the form of chips (Komandurai,1993). Among the various metal cutting process available,Grinding is one of the important metal cutting process used extensively in the finishing operation of discrete components. It is a versatile and also finish machining process in the production of components requiring close dimensional tolerances, geometrical accuracies and required surface finish (Rajmohan et al.,1994). Most of the production processes are incomplete without grinding process.According to Subramanian (1999), it is a major manufacturing process,which accounts for about 25% of the total expenditure on machining operations in industrialized countries. Almost all the engineering components are processed in grinding machining machines at some stages of its production. Grinding is a slow process in terms of unit removal of the stock. Hence,other methods are used first to bing the work close to its required dimensions and then it is ground to achieve the desired finish. In some applications,grinding is also employed for higher metal removal rate. In such heavy duty grinding operations more abrasive is consumed. In these cases,the main objective is to remove more amount of material that too as quickly and effectively as possible. Thus,the grinding process can be applied successfully to almost any component requiring precision or hard machining and it is also one of the widely used methods of removing material from the work piece after hardening. In order to decrease the cost and increase the production rate, the grinding machine must be set to operate within the shortest possible grinding cycle time. Hence, it is often important to set the correct grinding machine parameters so as to produce parts of required quality. The selection of grinding parameters if it is done on hit and miss technique not only wastes time but also leads to an inefficient process.To over come this difficulty, Gupta et al. (2001) in their work optimized the grinding process parameters using the enumeration method. The parameters should be selected so as to result in an optimal solution. Selection of grinding process parameters is made easy employing the “Expert system”. Shaji and Radhakrishnan (2002) analyzed the process parameters such as speed, feed, unfeed and mode of dressing as influential factors on the force components and surface finish developed based on Taguchi’s Experimental design methods. Fengguo Cao et al.(2003) developed the concept of integrating neural network, grey relational analysis and genetic algorithm for the optimization of process parameters in increased. Explosive Electrical Discharge Grinding Process lies in the proper selection and introduction of suitable design of experiment at the earliest stage of the process and product development cycles so as obtain quality and productivity improvement. Among the existing types of grinding processes, cylindrical grinding process is the one , which is very widely used in the finish machining of number of automobile components with surfaces of revolution. In cylindrical grinding process, the frictional resistance encountered between the work material and the tool, chip tool interface and the resistance to deformation during shearing of the chips contributes to rise in temperature at the contact zone (Trigger et al. 1951). The temperature generated is not only very high but the temperature gradients are also severe. Such temperatures of sufficient magnitude can cause adverse changes in workpiece metallurgical structure, loss in dimensional accuracy and accelerated wear [or] dulling of the tool (Des Ruisseaux and Zerkle, 1970; Takashi Ueda et al., 1985). In addition to causing surface damage,grinding heat may cause thermal expansion/distortion in the component ground and thus adversely affect the attainable accuracy.Masuda and Shiozaki(1974) demonstrated how grinding heat in plunge surface grinding results in out-of-flatness of the finished part. Better flatness was obtained with smaller depths of cut and higher workpiece velocities. Both of them cause lesser grinding heat and with increased coolant flow rate the cooling of the workpiece is enhanced and the thermal distortion is minimized. Chandrsekar et al. (1996) studied the thermal aspects of surface finishing process. In grinding, the localized abrasive workpiece contact pressures and high sliding speed produce high temperatures at the interface between an abrasive particle and the work surface, as well as in the work sub-surfaces due to frictional heating. High temperatures are the important source of damage on the machined surface. First, the transient temperature and the temperature gradient are the principle sources for residual stresses and micro cracking on ground surfaces. Secondly, the localized temperatures can cause warping of the components being machined, especially, when it is of small size and has a relatively large surface area to volume ratio. This is a serious problem in the finishing of small electronic devices such as recording heads. Thirdly, this high temperature can also lead to phase transformations in the materials being machined. The nature of grinding damage was surveyed by Tarasov (1950), who identified three main kinds of grinding damage, namely cracking, rehardening burn and tempering burn. During grinding of hardened steel, if the surface temperature of the work piece is sufficiently high, the surface reaustenizes and is rapidly quenched. Consequently, there is a formation of brittle, untempered martensite at the surface. This type of thermal damage is also commonly referred to as workpiece burn and is highly undesirable (Tarasov,1950; Torrance,1978). A martensitic type of phase transformation also occurs during the grinding of toughened zirconia. Here, the transient mechanical and thermal stresses generated during grinding drives the transformation. These forms of thermal damage change the mechanical, magnetic and electrical properties of the work materials. The local temperatures play an important role in the degradation of the abrasive particles and the bonding property of the material. The heat generated during grinding is characterized by, i) Instantaneous concentrated source, ii) High rate of liberation,and iii) Very small contact period. Heat associated with the energy expended by grinding is transported away from the grinding zone by the work piece, grinding fluid, grinding chips and grinding wheel. Of particular interest is the fraction of the total grinding energy transported to the work piece at the grinding zone, which causes the rise in workpiece temperature and possible thermal damage. For regular grinding with conventional Aluminum oxide wheels, the energy partition to the work piece typically ranges from 60-80% depending on the actual grinding situation (Malkin and Anderson,1974; Rowe et al., 1995 and 1997). Only a few isolated attempts have been reported so far on experimental analysis of the temperature developed at the wheelwork contact zone, energy partition ratio, grain contact time and thermal damages. At this point, it appears that practical optimization strategy and reliable mathematical models are still required to analyze the thermal damage in grinding. Field and Kahles (1971) investigated the dissipation of heat in grinding and the resulting influence on the surface integrity of the work piece. Guo and Malkin (1992) described that depending on the grinding condition the heat flux takes part mainly via the work piece and leads to a large thermal loading in the surface. This thermal load is superimposed by mechanical load causing a high temperature in the surface. This thermo-mechanical load causes some undesired alterations in the surface layer, like cracks,tempered zone or white etching areas (WEA). Shaw and Vyas (1994) gave an impressive theoretical description of metallurgical changes in ground surfaces. Under abusive grinding conditions, the formation of heat-affected zone was observed. Des Ruisseaux and Zerkle (1970) analyzed that the heat-affected zone under abusive grinding conditions damages the ground surface of the hardened steel very frequently. A thermally damaged component may therefore incur a significant cost to the manufacturer in failing quality standard. Thus, the thermal phenomena play a key role in the economics and mechanics of abrasive machining processes. An estimation of the amount of energy generated ,work surface temperature and an understanding of their role in metallurgical changes on ground surfaces are still challenging to the production engineers (Soyes and Maris 1978). Malkin and Fedoseev (1991) analyzed the method to predict the undesired alterations to avoid thermal damages in grinding gardened steel. In any case, the generated heat quantities in grinding are considered as a restricting factor. The invention of advanced grinding processes, which enabled the surface hardening of steel parts, was described for the first time in 1994. In such operations,named grind hardening, the dissipated heat in grinding is utilized to induced martensitic phase transformation in the surface layer of components (Brinksmeier and Brockhoff, 1997). Better surface finish with increased hardness at the surface by utilizing the heat generated during grinding is possible under optimum operating conditions. Thus, one of the area for the researchers to concern about the unique optimal settings of grinding process parameters - Depth of cut ,Number of passes, Wheel speed and work speed for maximizing the surface hardness and minimizing the surface roughness while grinding AISI steel materials with Al2O3 grinding wheels. “Ishikawa cause effect diagram”of machining is studied to identify the influential process parameters that may affect the surface integrity of grounded parts by Ramamoorthy et al., 2001 and; Harisingh et al., 2004. Taguchi’s parameter design approach has been used to accomplish the objective. A special mathematical tool known as grey relational analysis can be used with response graph approach and signal to noise ratio approach for the optimization. It is well known that physical surface properties can determine the lifetime and the function of highly loaded workpiece and components. For this reason, manufacturing industries require information about the techniques to influence the surface state of workpiece and achieve consistent properties (Kegg, 1982). This interest has its importance due to the fact that magnitude of the residual stress interferes on the fatigue strength of the materials (Novasaki et al., 1996). Residual srtess is the most representative parameter to describe the quality of the surface (Brinksmeier et al., 1982) among various surface alterations like phase transformations, hardness variations, micro cracks,grinding burn etc. Banerjee and Chattopadhyay (1987) investigated the control of residual stress in grinding by cryogenic cooling which results in much less tensile residual stresses. Kruszynski et al. (1991) made an attempt to predict residual stresses in grinding of metals with the aid of a new grinding parameter. Hucker (1994) showed that there was a quantitative relation between the effective work-surface temperature and the residual stress produced on ground surfaces of hardened steels. X-ray diffraction techniques were used to measure the residual stresses. It was reported that CBN grinding is found to produce compressive stress at the surface in contrast to Al2O3 grinding. However, many of the researches proved that under the conditions of martensitic formation (rough grinding) compressive residual stresses are formed when ground with Al2O3 wheel. Brockhoff and Brinksmeier (1997) in their comprehensive view on grind hardening fund out that compressive residual stresses are existing in the White Etching Areas, which continue into the area of etchable martensite and which are compensated by low tensile residual stresses in a greater distance from the surface. Litmann and Wulff (1955) found that for hardened steels, which have been burned during grinding, the workpiece sub-surface consists of a rehardened zone near the surface and a softened tempered zone beneath it. This would suggest that the onset of burning is characterized by the formation of austenite over some portion of the workpiece sub-surface. Rehardening at the surface occurs by acicular martensite ( that appears in the form of parallel needles within former austenite grains ) formation as the cooler material in the bulk of the workpiece quenches the surface. This refers to phase transformation in grinding. After grinding under ideal conditions, the ground surface will be crack free and will exhibit compressive residual stresses favorable for corrosion resistance and long life under cyclic loading conditions. In contrast, many grinding conditions are such that the surface produced suffers tensile stresses, sub-surface cracking and oxidation leading to failure in surface. In order to strike a balance between quality and strength in grounded parts it is desirable to have a control over the residual stress. This necessitates a detailed study of the free work-surface temperature, amount of heat generated and the magnitude of residual stress formed. 對磨削的一些觀察 為了使在零部件的生產(chǎn)中達(dá)到預(yù)期的形狀、尺寸和精度，機(jī)械加工被廣泛運(yùn)用于生產(chǎn)加工工藝中。機(jī)械加工過程中會(huì)運(yùn)用到一個(gè)或多個(gè)切削工具，來去除工件上不需要的部分，使之成為切屑。在眾多已應(yīng)用的金屬切削工藝中，磨削加工是金屬加工工藝常用于零件最終加工的重要加工工藝之一。它用途廣泛，也經(jīng)常用于尺寸公差、幾何精度和表面精度要求高的零件的機(jī)械加工工藝中。絕大多數(shù)產(chǎn)品的生產(chǎn)工藝中都少不了磨削加工。根據(jù)Subramanian的統(tǒng)計(jì)數(shù)據(jù)，在工業(yè)國家的生產(chǎn)支出中，磨削加工占了25%，處于主要地位。幾乎所有的工程零件在其生產(chǎn)的某些階段會(huì)在磨削機(jī)床上加工。 在工件的單元切削中，磨削加工是一個(gè)緩慢的過程。因此，在工件開始加工時(shí)，一般采用其他的加工方式使工件達(dá)到與要求相近的精度，然后采用磨削完成加工。在某些應(yīng)用中，磨削也具備更高的金屬切削效率。在如重載磨削中，更多的磨料會(huì)被消耗，在這些情況下，盡可能快而有效去除更多的金屬材料是主要的目標(biāo)。因而，磨削加工能成功地用于任何高精度或難加工零件的加工過程中，并且它也是可廣泛應(yīng)用于硬化表面材料去除的加工工藝之一。 Shaw曾報(bào)告稱，磨削加工是存在很多相關(guān)變量的復(fù)雜工藝，而這些相互作用的變量是同磨削方式所決定的。在平面磨削中所產(chǎn)生的幾何形狀會(huì)受到如下因素的影響： 1. 砂輪因素：砂輪直徑、磨粒類型和尺寸、砂輪等級、砂輪構(gòu)造、粘結(jié)劑、敷 料工藝、砂輪的平衡等級等。 2. 工件因素：加工表面硬度、構(gòu)造、化學(xué)特征等。 3. 機(jī)床因素：主軸和工作臺(tái)剛度、阻尼、動(dòng)力特性等。 4. 加工參數(shù)：砂輪轉(zhuǎn)速、進(jìn)給量、背吃刀量、磨削液等。 為了減少消耗，提高生產(chǎn)效率，磨削機(jī)床必須設(shè)定加工時(shí)間處于最短的可能磨削周期內(nèi)。因此，設(shè)置正確磨削機(jī)床參數(shù)對獲得需要的精度往往非常重要。如果磨削參數(shù)選擇不符合技術(shù)要求，就會(huì)導(dǎo)致時(shí)間浪費(fèi)效率低下。為了解決這個(gè)問題，Gupta在他們的研究中，采用列表的方法來使磨削參數(shù)最優(yōu)化。參數(shù)的選取應(yīng)使工作方案最優(yōu)化，當(dāng)采用“專家系統(tǒng)”時(shí)，磨削工藝參數(shù)的選取就變得容易了。Shaji和Radhakrishnan在Tagudhi的實(shí)驗(yàn)設(shè)計(jì)方法基礎(chǔ)上分析了砂輪轉(zhuǎn)速、進(jìn)給量、背吃刀量、敷料的方式對磨削力的構(gòu)成、表面加工的影響。Fengguo Cao提出了一體化神經(jīng)網(wǎng)絡(luò)、灰色相關(guān)分性分析、遺傳算法的概念，來對工藝參數(shù)進(jìn)行優(yōu)化提高。 爆炸式電火花磨削工藝正是立足于對最早工藝階段和產(chǎn)品開發(fā)周期的合理實(shí)驗(yàn)設(shè)計(jì)的選擇推廣上，來獲得品質(zhì)和效率的提升。 在已有的磨削工藝形式中，外加磨削廣泛應(yīng)用于汽車回轉(zhuǎn)零件的表面加工中。在外圓，產(chǎn)生于工件材料與刀具之間的摩擦阻力，刀具表面的剪切變形抗力會(huì)使得接觸區(qū)域的溫度上升。產(chǎn)生的溫度很高并且分布很不均勻，這樣劇烈的高溫會(huì)使工件的金相結(jié)構(gòu)發(fā)生不利的改變，使其尺寸精度喪失，并且加速刀具鈍化。 除了導(dǎo)致表面損壞，磨削熱也會(huì)使工件在磨削過程產(chǎn)生熱膨脹或熱變形，從而對工件精度產(chǎn)生不利的影響。Masuda和Shiozaki闡述了磨削熱如何尋到工件表面變得不平整。當(dāng)采用較小的切深和更高的切削速度時(shí)，會(huì)獲得更高的平面度。同時(shí)，也能減少磨削熱的產(chǎn)生。再加快冷卻液的流動(dòng)速率，使工件冷卻效果加強(qiáng)，能使熱變形減小。 Chandrsekar研究了表面加工過程的熱效應(yīng)。在磨削過程中，局部的接觸應(yīng)力和高的滑動(dòng)速度會(huì)在工件和磨削刃接觸面產(chǎn)生高溫，同時(shí)在次層面產(chǎn)生摩擦熱。高溫是造成已加工表面損壞的重要因素。首先，分布不均勻的瞬態(tài)高溫是工件殘余應(yīng)力和表面微裂紋的主要來源。第二，局部高溫會(huì)使已加工的部分發(fā)生形變。尤其是對尺寸較小卻具有較大體積比率的工件，變形尤為嚴(yán)重，這對于某些小型電子設(shè)備如電磁記錄頭的加工，是一個(gè)很嚴(yán)峻的問題。第三，高溫會(huì)導(dǎo)致已加工材料的物相發(fā)生改變。 Tarasov對磨削操作的性質(zhì)做了調(diào)查研究，確定了三種主要的損傷類型，分別是開裂，二次淬火燒傷和高溫?zé)齻?。在磨削硬質(zhì)的鋼材時(shí)，如果表面溫度過高，就會(huì)發(fā)生表面再次奧氏體化，并急速冷卻，從而在工件表面會(huì)形成具有的回火馬氏體。這種形式的熱損傷也是覺的工件燒傷形式，需要避免。在更質(zhì)氧化鋯的磨削過程中，也會(huì)發(fā)生類似馬氏體類型的物相變化。這種變化是同磨削過程中產(chǎn)生的瞬態(tài)機(jī)械應(yīng)力和熱應(yīng)力所導(dǎo)致的。這些形式的熱損傷會(huì)改變加工材料的機(jī)械和電磁特性。 局部的高溫在磨粒鈍化和材料粘合性下降的過程中起主導(dǎo)作用。磨削中產(chǎn)生的熱是由以下因素決定的： 1. 瞬時(shí)的集中源 2. 高速率的釋放 3. 極小的接觸時(shí)間 磨削過程中產(chǎn)生的磨削熱可以通過工件、磨削液、切屑及磨削砂輪傳遞出磨削區(qū)域。而其中通過工件傳遞的磨削熱會(huì)使工件升溫而可能導(dǎo)致熱損傷。對于采用氧化鋁砂輪的磨削加工，由工件傳遞的熱量大約在60%到80%之間視具體磨削狀況而定。到目前只有一少部分單獨(dú)的關(guān)于齒輪接觸區(qū)溫升、能量分配比、磨粒接觸時(shí)間和熱損傷實(shí)驗(yàn)分析的嘗試。在這個(gè)方面，還是需要切實(shí)可行的優(yōu)化方法和可靠的數(shù)學(xué)模型來分析磨削中的熱損傷問題。 Filed和Kahles研究了磨削熱的散失及其對工件表面完整性的影響。Guo和Malkin認(rèn)為依據(jù)磨削所處的加工狀態(tài)，磨削熱主要通過工件傳遞，從而導(dǎo)致工件表面的一個(gè)大的熱應(yīng)力。這個(gè)熱應(yīng)力是由于機(jī)械應(yīng)力在工件表面產(chǎn)生高溫而形成的。這種熱—機(jī)械應(yīng)力會(huì)在工件表層造成不想要的變化，如開裂，回火區(qū)或白蝕區(qū)（WEA）。 Shawl和Vyas給出了一個(gè)令人信服的磨削層金相變化的理論描述。在惡劣的磨削條件下，熱影響區(qū)的結(jié)構(gòu)可以被觀察到。Des Ruisseaux和Zerkle分析，極端磨削條件下熱影響區(qū)會(huì)頻繁地破壞磨削加工表面。一個(gè)熱損傷的零件會(huì)使生產(chǎn)商的品質(zhì)標(biāo)準(zhǔn)失敗，這無疑是一個(gè)很大的代價(jià)。因而，發(fā)熱現(xiàn)象在經(jīng)濟(jì)學(xué)和磨削加工過程中發(fā)揮重要作用對于產(chǎn)生熱量的估計(jì)，工件表面溫度和對金相變化的影響仍舊是產(chǎn)品工程師所面臨的挑戰(zhàn)。Malkin和Fedoseev分析出了在磨削硬化鋼時(shí)可預(yù)測不想要的變化的方法，來避免熱損傷。無論怎樣，磨削所產(chǎn)生的熱是影響加工的負(fù)面因素。能夠用于硬質(zhì)表面加工的先進(jìn)磨削技術(shù)在1994年第一次出現(xiàn)。在如名為硬質(zhì)磨削的加工中，傳導(dǎo)的熱量被用來引起工件表層金屬的馬氏體轉(zhuǎn)變。 在最佳的加工條件下，利用好磨削中的熱來提高表面質(zhì)量和增加表面硬度是可能的。因此，獨(dú)特合理的磨削參數(shù)是研究人員熱衷的領(lǐng)域之一。切削深度、進(jìn)給方式、砂輪轉(zhuǎn)速、工件速度怎么確定，來增加Al2O3砂輪磨削AISI鋼材時(shí)的表面硬度，減小其表面粗糙度。 “Ishikuwa變量效果圖”可用來分析工藝參數(shù)對磨削表面質(zhì)量的影響。“Taguchi參數(shù)設(shè)計(jì)”已被用來完成上面的目標(biāo)。一個(gè)通過分析反應(yīng)曲線和聲音比率數(shù)學(xué)工具可以使得工藝參數(shù)最優(yōu)化。 眾所周知，表面物理特性能決定高負(fù)載工件的能力和使用壽命。正是于此，制造業(yè)需要關(guān)于影響表面質(zhì)量的技術(shù)和統(tǒng)計(jì)學(xué)參數(shù)。這方面的重要性是由殘余應(yīng)力的大小對材料疲勞強(qiáng)度的影響而決定的。殘余是眾多表面變化如物相轉(zhuǎn)變、硬度轉(zhuǎn)變、微觀裂紋、磨削燒傷等中最能描述表面質(zhì)量的代表性參數(shù)。 Banerjee和Chattopadhyay進(jìn)行了可導(dǎo)致更少拉伸殘余應(yīng)力的低溫冷卻磨削的殘余應(yīng)力控制的研究。Kruszyski進(jìn)行了采用新的磨削參數(shù)進(jìn)行磨削，以此評估殘余應(yīng)力的研究。Hucker發(fā)現(xiàn)高效的工作表面溫度與硬質(zhì)鋼磨削表面的殘余應(yīng)力之間存在數(shù)量關(guān)系。X射線衍射技術(shù)被應(yīng)用于殘余應(yīng)力的測定。據(jù)報(bào)道，較之于Al2O3磨削，研究人員發(fā)現(xiàn)CBN磨削產(chǎn)生更能產(chǎn)生壓應(yīng)力。但是，很多研究人員證實(shí)，在馬氏體形成的條件下（粗加工）采用Al2O3砂輪磨削時(shí)產(chǎn)生壓應(yīng)力。 Brokhoff和Brinksmeier在他們對磨削的綜合看法中指出，壓應(yīng)力存在于白蝕區(qū)，并延伸到馬氏體蝕刻區(qū)，從離表面更遠(yuǎn)的距離獲得較小的拉伸殘余應(yīng)力補(bǔ)償。Litman和Wuff發(fā)現(xiàn)已經(jīng)發(fā)生過磨削燒傷的硬質(zhì)鋼，其次表層是由接近表面的再次硬化區(qū)和其下方的回火軟化區(qū)組成。這將表明，燒傷是工件次表層上形成奧氏體所導(dǎo)致的，針狀馬氏體（出現(xiàn)在平等針面的成形前的奧氏體晶粒）的形成成為工件表面淬火的冷卻體，這涉及到了磨削物相變化。 在理想條件下磨削過后，磨削表面不會(huì)開裂，并且會(huì)產(chǎn)生壓應(yīng)力阻礙腐蝕，在循環(huán)應(yīng)力條件下的工作壽命延長。相對地，很多磨削表面處于拉應(yīng)力狀態(tài)，次層裂紋擴(kuò)展和氧化會(huì)使表面質(zhì)量惡化。為了在質(zhì)量精度和工件強(qiáng)度之間達(dá)到平衡，必須控制殘余應(yīng)力。這需要對工作表面溫度、產(chǎn)生的熱量和殘余應(yīng)力的構(gòu)成進(jìn)行詳細(xì)的研究。