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滾動軸承滾道磨削表面形貌及變質(zhì)層研究

發(fā)布時間:2018-01-03 16:43

  本文關(guān)鍵詞:滾動軸承滾道磨削表面形貌及變質(zhì)層研究 出處:《山東大學(xué)》2014年博士論文 論文類型:學(xué)位論文


  更多相關(guān)文章: 軸承滾道磨削 磨削變質(zhì)層 表面粗糙度


【摘要】:高性能滾動軸承是重大裝備及精密裝備的核心部件,高速、重載、高精度滾動軸承的自主研發(fā)能力落后,已成為嚴(yán)重制約我國裝備制造業(yè)快速發(fā)展的瓶頸。全面提升軸承的設(shè)計和制造水平、改進制造工藝已成為軸承行業(yè)亟待解決的問題。滾動軸承滾道作為軸承的工作表面,其表面質(zhì)量及尺寸精度將直接影響到軸承的工作性能和使用壽命。軸承滾道磨削工藝作為關(guān)鍵制造工序之一,磨削過程在軸承滾道表層產(chǎn)生的不良影響將延續(xù)到軸承成品,影響軸承的工作性能。磨削過程作為高比能的加工工藝過程,去除單位體積的材料需要更高的能量投入,由高比能轉(zhuǎn)化產(chǎn)生的高溫對工件材料的影響是很難避免的。因此,選擇合理的磨削參數(shù),盡可能降低磨削過程對滾道表面質(zhì)量所帶來的負(fù)面影響,是提升磨削工藝水平的關(guān)鍵問題。本文以磨削表面形貌和磨削變質(zhì)層為研究對象,以磨削弧區(qū)中磨粒與工件材料的微觀相互作用為切入點,建立了磨削參數(shù)與磨削表面粗糙度、磨削變質(zhì)層厚度之間的數(shù)值關(guān)系,搭建了軸承滾道磨削實驗平臺并進行了實驗研究,結(jié)合理論研究提出了綜合考慮粗糙度、變質(zhì)層厚度及加工效率的軸承滾道磨削工藝參數(shù)規(guī)劃方法,對進一步提升軸承滾道磨削工藝具有一定的理論意義和實用價值。本文主要研究工作如下: (1)對磨削弧區(qū)中磨粒與工件材料微觀作用機理進行了深入分析研究,建立了相關(guān)數(shù)學(xué)模型;谀チA6确䦶恼龖B(tài)分布、位置服從隨機分布,給出了砂輪單位體積磨粒數(shù)量的計算方法。將磨削弧區(qū)重新定義為“磨削弧長×磨削寬度×最大未變形切屑厚度”的空間區(qū)域,認(rèn)為磨粒在經(jīng)過磨削弧區(qū)時,經(jīng)歷了未接觸、滑擦、耕犁和切削四個階段。分析得到了這四個階段各自的起始位置及長度與磨粒直徑、磨粒突起高度和磨粒位置之間的數(shù)學(xué)關(guān)系。通過求解由微觀上推導(dǎo)出的切削磨粒所去除材料的總體積,等于宏觀上的比去除率的方程得到最大未變形切屑厚度。通過對磨粒在磨削弧區(qū)內(nèi)各階段的分析,得到滿足磨削弧區(qū)內(nèi)各類磨粒的磨粒直徑、磨粒突起高度和磨粒位置這三個變量的積分區(qū)間,從而得到了磨削弧區(qū)內(nèi)各類磨粒的數(shù)量。將磨削弧區(qū)離散,在每一區(qū)間內(nèi)計算各類磨粒數(shù)量,得到各類磨粒在磨削弧區(qū)中的分布。理論分析及實例計算結(jié)果表明,未接觸磨粒數(shù)量占磨?倲(shù)量的一半且沿磨削弧長減少,滑擦磨粒在整個磨削弧區(qū)中都存在且沿磨削弧長增加,耕犁及切削磨粒在磨削弧區(qū)中的某一位置處才開始出現(xiàn)。對磨削弧區(qū)微觀作用機理的分析研究為本文后續(xù)工作奠定了理論基礎(chǔ)。 (2)建立了考慮砂輪修整和磨損影響的磨削表面形貌模型,得到磨削參數(shù)與磨削表面粗糙度之間的數(shù)值關(guān)系。在工件表面定義輪廓線LA,描述表面形貌,認(rèn)為砂輪表面的磨粒依次經(jīng)過并改變輪廓線的形狀。根據(jù)磨粒突起高度、磨粒直徑以及磨粒位置和磨粒切入深度之間的數(shù)學(xué)關(guān)系,同時考慮了磨粒粒度、磨粒位置的分布特性,確定了經(jīng)過輪廓線的磨粒的直徑、磨粒在工件表面法向和磨削寬度方向上的位置。所有磨粒經(jīng)過后,得到了磨削表面形貌LA*及粗糙度Ra。將理論計算結(jié)果與相關(guān)文獻實驗數(shù)據(jù)進行對比,驗證了理論模型,分析了磨削參數(shù)對磨削表面粗糙度的影響?紤]砂輪修整和磨損的影響,建立了砂輪修整磨損輪廓線Ldw,得到了考慮修整和磨損影響的磨削表面形貌及粗糙度模型。當(dāng)磨粒經(jīng)過輪廓線LA之前,被修整磨損輪廓線Ldw改變其形狀,將修整和磨損的影響帶入到磨削表面形貌中。進行了修整導(dǎo)程單因素磨削實驗,將理論計算結(jié)果與實驗數(shù)據(jù)進行對比,驗證了理論模型,分析了修整參數(shù)對磨削表面粗糙度的影響。將平面磨削參數(shù)等價轉(zhuǎn)換為軸承滾道磨削參數(shù),將相關(guān)理論應(yīng)用于軸承滾道磨削過程中,得到了軸承滾道磨削參數(shù)與表面粗糙度之間的數(shù)值關(guān)系。結(jié)果表明,軸承滾道磨削表面粗糙度只與精磨階段的磨削參數(shù)相關(guān),精磨階段磨削深度較小,滾道粗糙度受工件轉(zhuǎn)速的影響較大;谛拚麉(shù)與表面粗糙度之間的數(shù)值關(guān)系,可評價修整導(dǎo)程及修整深度的合理性,基于磨削參數(shù)與表面粗糙度之間的數(shù)值關(guān)系,可選擇滿足磨削工藝粗糙度要求的工件轉(zhuǎn)速。 (3)建立了磨削參數(shù)與磨削暗層厚度之間的數(shù)值關(guān)系,提出了考慮暗層厚度、粗糙度和加工效率的軸承滾道磨削參數(shù)規(guī)劃,分析了磨削白層的產(chǎn)生機理。建立了單顆磨粒磨削力模型,結(jié)合各類磨粒數(shù)量在磨削弧區(qū)的分布,得到了總熱流密度在磨削弧區(qū)的分布。在磨削弧區(qū)各區(qū)間內(nèi)計算熱量分配比,得到了傳入工件的熱流密度的分布。建立有限元模型,將傳入工件的熱流密度加載,計算得到了磨削溫度場。基于磨削溫度場內(nèi)工件表層各點的溫度變化歷程,得到了磨削暗層的厚度。將磨削暗層的計算方法應(yīng)用于軸承滾道磨削過程中,得到了磨削參數(shù)對軸承滾道磨削暗層厚度的影響規(guī)律。結(jié)果表明,軸承滾道磨削暗層厚度受磨削深度的影響較大;谀ハ鲄(shù)對軸承滾道磨削粗糙度和磨削暗層厚度的影響規(guī)律,提出了綜合考慮磨削粗糙度、變質(zhì)層厚度和加工時間的磨削工藝參數(shù)規(guī)劃的方法。根據(jù)本方法得到的軸承滾道磨削工藝參數(shù),既可滿足工藝對粗糙度的要求,還可保證不產(chǎn)生磨削暗層,同時加工效率也是最高的;趩晤w磨粒切削的有限元模擬,分析了磨削白層的產(chǎn)生機理,結(jié)果表明,當(dāng)磨削弧區(qū)總體溫升低于工件材料相變溫度時,由單顆磨粒切削也會產(chǎn)生白層組織,此時白層組織在工件表面的分布是隨機和不連續(xù)的。 (4)搭建了角接觸球軸承B7008C內(nèi)圈磨削力及磨削溫度實驗平臺,進行了實驗研究。通過測量砂輪電機功率獲取切向磨削力,采用改進的頂式熱電偶方法測量獲取了磨削溫度場,在金相顯微鏡下觀察了工件表層的變質(zhì)層的組織及深度。將測量及理論計算數(shù)據(jù)進行了對比,結(jié)果表明理論計算結(jié)果吻合良好,其中切向磨削力預(yù)測誤差小于7%、磨削溫度場分布及變化歷程、磨削暗層厚度、磨削白層特征均與本文理論預(yù)測結(jié)果相符合,從而證明了本文理論適用于軸承滾道磨削研究。
[Abstract]:High performance rolling bearing is the core component, and precision equipment for major equipment of high speed, heavy load, high precision rolling bearing ability of the independent research and development lags behind, has become a serious bottleneck restricting the rapid development of China's equipment manufacturing industry. To enhance the bearing design and manufacturing level, improve the manufacturing process has become an urgent problem in the rolling bearing industry. As the working surface of the bearing rolling bearing, the surface quality and dimensional accuracy will directly affect the working performance and service life of the bearing. The bearing raceway grinding process as one of the key manufacturing process of grinding process, adverse effects on the surface of the bearing raceway will continue to affect the working performance of finished bearings, bearing the grinding process. As the processing technology of high energy process, the removal of unit volume material requires higher energy input, high temperature produced by the high energy conversion of the workpiece material. Sound is very difficult to avoid. Therefore, reasonable choice of grinding parameters, reduce the negative impact brought about by the grinding process of raceway surface quality as much as possible, is the key to improve the level of the grinding process. The surface topography and grinding affected layer as the research object, in the grinding zone in the abrasive and workpiece material micro interaction as the starting point, establish the grinding parameters and grinding surface roughness, the numerical relationship between the grinding affected layer thickness, build a bearing raceway grinding experimental platform and experimental research, combined with theoretical research is proposed considering road roughness, grinding parameters and planning method of roll bearing metamorphic layer thickness and processing efficiency to further enhance the bearing raceway grinding process has a certain theoretical significance and practical value. The main research work are as follows:
(1) of particles and the micro mechanism of workpiece material grinding arc area were studied in this paper, the mathematical model was established. The particle size obeys normal distribution based on the position of random distribution, calculation method of grain number per unit volume of grinding wheel is presented. Will be redefined as "grinding arc length x grinding width * maximum undeformed chip thickness" region of grinding zone, that abrasive after grinding arc area, has not contact, sliding, ploughing and cutting four stages. Analysis of the four stages of their starting position and length and particle diameter, height and abrasive the mathematical relationship between wear particle position. Through cutting solution derived from micro abrasive particle total volume of material removal, the removal rate is equal to the macro than the equation to get the maximum undeformed chip thickness. The abrasive in the grinding zone within the Stage of the analysis, to satisfy all kinds of grinding abrasive diameter arc zone abrasive, abrasive grain protrusion height of integral interval and the three variable abrasive position, resulting in various types of abrasive grinding arc zone number. The discrete grinding zone, all kinds of abrasive grain quantity calculation in each interval. Get all kinds of abrasive particles in the grinding zone distribution. The theoretical analysis and example calculation results show that the no contact number of abrasive particles accounted for half of the total number of grain grinding and grinding along the arc length decreases, the sliding abrasive in the grinding zone are grinding and along the arc length increases, ploughing and cutting abrasive in the grinding zone in a position began to appear. Analysis of the grinding zone, micro mechanism provides a theoretical foundation for the follow-up work.
(2) the establishment of the dressing and wear surface topography model considering the influence of grinding parameters and grinding surface, get the numerical relationship between the degree of roughness on the surface of the workpiece contour. The definition of LA, describe the surface morphology, the abrasive wheel surface that passes and change shape. According to the abrasive grain protrusion height, mathematics the relationship between particle size and particle position and between the abrasive cutting depth, considering the particle size, distribution characteristics of abrasive position, determined by particle diameter profile of the abrasive particles on the surface of the workpiece and the grinding method to the width direction of the position. All debris after, get the grinding surface roughness of LA* and Ra. will compare the theoretical results with the literature experimental data, verify the theoretical model, analysis of the grinding parameters on the grinding surface roughness. Considering the grinding wheel wear and the whole Influence of established grinding wear contour Ldw, the dressing and morphology of worn surface grinding effect and roughness model. When abrasive through previous contour LA, wear contour be trimmed Ldw change its shape into the dressing will affect and wear to the grinding surface. The dressing lead single factor grinding experiment, comparing the theoretical calculation results and the experimental data, verify the theoretical model, analysis of the dressing parameters on the grinding surface roughness. The influence of grinding parameters will be converted to equivalent bearing raceway grinding parameters, the relevant theory is applied to the bearing raceway grinding process, the grinding parameters of bearing raceway between surface roughness and the numerical relationship. The results show that the bearing raceway surface roughness of grinding and fine grinding stage grinding parameters, grinding grinding depth, roughness of the raceway Influence of workpiece speed greatly. The dressing parameters and surface roughness based on the numerical relationship between the degree of rationality, can evaluate the dressing lead and dressing depth, grinding parameters and surface roughness based on the numerical relationship between the degree of choice, meet the requirements of rough grinding workpiece speed.
(3) to establish the numerical relationship between grinding parameters and grinding surface layer thickness, considering the dark layer thickness, roughness and machining efficiency of the bearing raceway grinding parameter planning, analyzes the produce mechanism of grinding white layer. A single grinding force model, the combination of all kinds of distribution of grain number in the grinding mill the arc area, obtained the distribution of total heat flux in the grinding zone. In each interval in grinding area calculation of heat distribution ratio, the heat flux distribution of workpiece. The finite element model is established, the incoming heat flux load calculation to workpiece, the grinding temperature field. The temperature change process of grinding temperature at each point on the surface of the workpiece, grinding dark layer thickness is obtained. The application of calculation method of grinding dark layer in bearing raceway grinding process, the law of the effect of grinding parameters on the bearing raceway grinding dark layer thickness. Results Show that the roller bearings influence road grinding thickness by dark grinding depth. The grinding parameters on the bearing raceway grinding effect of roughness and grinding dark layer thickness based on the comprehensive consideration of surface roughness of grinding method, grinding parameters planning metamorphic layer thickness and processing time. According to the bearing obtained by this method. Way of grinding process parameters, can satisfy the process on the roughness of the requirements, but also can ensure no grinding dark layer, and the processing efficiency is the highest. Single grain cutting based on finite element simulation and analysis of the formation mechanism of white layer in grinding. The results show that when the overall temperature rise below the transition temperature of grinding zone the workpiece material, the single grain cutting will produce a white layer, the white layer in the workpiece surface distribution is random and discontinuous.
(4) to build a B7008C inner ring angular contact ball bearing grinding force and grinding temperature experimental platform was studied. To obtain the tangential grinding force by measuring wheel motor power, using top thermocouple improved method acquire grinding temperature field, under the microscope to observe the metamorphic layer of the workpiece surface and the organization depth measurement and theoretical calculation. The data were compared, the results show that the theoretical calculation results are in good agreement, the cutting error is less than 7% to predict the grinding force, grinding temperature field distribution and the change process of grinding dark layer thickness, white layer characteristics are consistent with the theoretical prediction of grinding results, which proved that this theory is suitable for bearing study of roll grinding.

【學(xué)位授予單位】:山東大學(xué)
【學(xué)位級別】:博士
【學(xué)位授予年份】:2014
【分類號】:TH133.33

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