滚动轴承滚道磨削表面形貌及变质层研究

发布时间：2018-01-03 16:43

本文关键词：滚动轴承滚道磨削表面形貌及变质层研究　出处：《山东大学》2014年博士论文　论文类型：学位论文

【摘要】：高性能滚动轴承是重大装备及精密装备的核心部件,高速、重载、高精度滚动轴承的自主研发能力落后,已成为严重制约我国装备制造业快速发展的瓶颈。全面提升轴承的设计和制造水平、改进制造工艺已成为轴承行业亟待解决的问题。滚动轴承滚道作为轴承的工作表面,其表面质量及尺寸精度将直接影响到轴承的工作性能和使用寿命。轴承滚道磨削工艺作为关键制造工序之一,磨削过程在轴承滚道表层产生的不良影响将延续到轴承成品,影响轴承的工作性能。磨削过程作为高比能的加工工艺过程,去除单位体积的材料需要更高的能量投入,由高比能转化产生的高温对工件材料的影响是很难避免的。因此,选择合理的磨削参数,尽可能降低磨削过程对滚道表面质量所带来的负面影响,是提升磨削工艺水平的关键问题。本文以磨削表面形貌和磨削变质层为研究对象,以磨削弧区中磨粒与工件材料的微观相互作用为切入点,建立了磨削参数与磨削表面粗糙度、磨削变质层厚度之间的数值关系,搭建了轴承滚道磨削实验平台并进行了实验研究,结合理论研究提出了综合考虑粗糙度、变质层厚度及加工效率的轴承滚道磨削工艺参数规划方法,对进一步提升轴承滚道磨削工艺具有一定的理论意义和实用价值。本文主要研究工作如下： (1)对磨削弧区中磨粒与工件材料微观作用机理进行了深入分析研究,建立了相关数学模型。基于磨粒粒度服从正态分布、位置服从随机分布,给出了砂轮单位体积磨粒数量的计算方法。将磨削弧区重新定义为“磨削弧长×磨削宽度×最大未变形切屑厚度”的空间区域,认为磨粒在经过磨削弧区时,经历了未接触、滑擦、耕犁和切削四个阶段。分析得到了这四个阶段各自的起始位置及长度与磨粒直径、磨粒突起高度和磨粒位置之间的数学关系。通过求解由微观上推导出的切削磨粒所去除材料的总体积,等于宏观上的比去除率的方程得到最大未变形切屑厚度。通过对磨粒在磨削弧区内各阶段的分析,得到满足磨削弧区内各类磨粒的磨粒直径、磨粒突起高度和磨粒位置这三个变量的积分区间,从而得到了磨削弧区内各类磨粒的数量。将磨削弧区离散,在每一区间内计算各类磨粒数量,得到各类磨粒在磨削弧区中的分布。理论分析及实例计算结果表明,未接触磨粒数量占磨粒总数量的一半且沿磨削弧长减少,滑擦磨粒在整个磨削弧区中都存在且沿磨削弧长增加,耕犁及切削磨粒在磨削弧区中的某一位置处才开始出现。对磨削弧区微观作用机理的分析研究为本文后续工作奠定了理论基础。 (2)建立了考虑砂轮修整和磨损影响的磨削表面形貌模型,得到磨削参数与磨削表面粗糙度之间的数值关系。在工件表面定义轮廓线LA,描述表面形貌,认为砂轮表面的磨粒依次经过并改变轮廓线的形状。根据磨粒突起高度、磨粒直径以及磨粒位置和磨粒切入深度之间的数学关系,同时考虑了磨粒粒度、磨粒位置的分布特性,确定了经过轮廓线的磨粒的直径、磨粒在工件表面法向和磨削宽度方向上的位置。所有磨粒经过后,得到了磨削表面形貌LA*及粗糙度Ra。将理论计算结果与相关文献实验数据进行对比,验证了理论模型,分析了磨削参数对磨削表面粗糙度的影响。考虑砂轮修整和磨损的影响,建立了砂轮修整磨损轮廓线Ldw,得到了考虑修整和磨损影响的磨削表面形貌及粗糙度模型。当磨粒经过轮廓线LA之前,被修整磨损轮廓线Ldw改变其形状,将修整和磨损的影响带入到磨削表面形貌中。进行了修整导程单因素磨削实验,将理论计算结果与实验数据进行对比,验证了理论模型,分析了修整参数对磨削表面粗糙度的影响。将平面磨削参数等价转换为轴承滚道磨削参数,将相关理论应用于轴承滚道磨削过程中,得到了轴承滚道磨削参数与表面粗糙度之间的数值关系。结果表明,轴承滚道磨削表面粗糙度只与精磨阶段的磨削参数相关,精磨阶段磨削深度较小,滚道粗糙度受工件转速的影响较大。基于修整参数与表面粗糙度之间的数值关系,可评价修整导程及修整深度的合理性,基于磨削参数与表面粗糙度之间的数值关系,可选择满足磨削工艺粗糙度要求的工件转速。 (3)建立了磨削参数与磨削暗层厚度之间的数值关系,提出了考虑暗层厚度、粗糙度和加工效率的轴承滚道磨削参数规划,分析了磨削白层的产生机理。建立了单颗磨粒磨削力模型,结合各类磨粒数量在磨削弧区的分布,得到了总热流密度在磨削弧区的分布。在磨削弧区各区间内计算热量分配比,得到了传入工件的热流密度的分布。建立有限元模型,将传入工件的热流密度加载,计算得到了磨削温度场。基于磨削温度场内工件表层各点的温度变化历程,得到了磨削暗层的厚度。将磨削暗层的计算方法应用于轴承滚道磨削过程中,得到了磨削参数对轴承滚道磨削暗层厚度的影响规律。结果表明,轴承滚道磨削暗层厚度受磨削深度的影响较大。基于磨削参数对轴承滚道磨削粗糙度和磨削暗层厚度的影响规律,提出了综合考虑磨削粗糙度、变质层厚度和加工时间的磨削工艺参数规划的方法。根据本方法得到的轴承滚道磨削工艺参数,既可满足工艺对粗糙度的要求,还可保证不产生磨削暗层,同时加工效率也是最高的。基于单颗磨粒切削的有限元模拟,分析了磨削白层的产生机理,结果表明,当磨削弧区总体温升低于工件材料相变温度时,由单颗磨粒切削也会产生白层组织,此时白层组织在工件表面的分布是随机和不连续的。 (4)搭建了角接触球轴承B7008C内圈磨削力及磨削温度实验平台,进行了实验研究。通过测量砂轮电机功率获取切向磨削力,采用改进的顶式热电偶方法测量获取了磨削温度场,在金相显微镜下观察了工件表层的变质层的组织及深度。将测量及理论计算数据进行了对比,结果表明理论计算结果吻合良好,其中切向磨削力预测误差小于7%、磨削温度场分布及变化历程、磨削暗层厚度、磨削白层特征均与本文理论预测结果相符合,从而证明了本文理论适用于轴承滚道磨削研究。
[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.

【学位授予单位】：山东大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TH133.33

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