磨削温度的试验研究

经过试验和理论计算,研究了磨削区的最高磨削温度.详细探讨了热电偶测温技术的实质和过程.利用热电偶测量了磨削接触区的最高温度.对测量温度值与理论计算值进行了比较,试验结果与采用磨削热模型理论的计算结果基本一致.     

高效深磨中磨削温度和表面烧伤研究

介绍了一种高效深磨的磨削热模型——圆弧热源模型，该模型和直线倾斜平面模型相比改进了温度的预测；给出了圆弧热源磨削温度的积分公式和量纲一温度计算式；详细分析了热流量，推导了工件、砂轮、磨削液和磨屑的对流因子计算公式，在此基础上给出了最大接触温度的计算公式；使用J形热电偶测量了磨削接触面接近磨削烧伤时的最高磨削温度和磨削液沸腾的温度。实验结果与理论计算值对比表明，测量温度与理论计算温度有极好的一致性。     

金刚石节块与花岗石界面锯切温度的测量与分析

通过实验研究了干锯切花岗石过程中金刚石节块—花岗石接触界面的温度特性 ,并用康铜—纯铁薄膜热电偶在线测量了磨削弧区的温度响应。将实验结果与理论计算结果进行拟合 ,得到了热量传入花岗石的比例。实验结果表明 ,测得温度与三角形热源模型的计算结果吻合良好 ,薄膜热电偶完全可满足锯切实验条件对时间响应的要求 ,干锯切花岗石过程中传入金刚石工具的热量占总热量的 90 %以上     

铝合金Al6061微尺度磨削力热特性试验分析

微磨削加工是微尺度加工领域的一种重要的加工方法。基于铝合金Al6061建立微磨削力热特性的理论模型。设计铝合金Al6061材料的微磨削单因素试验,分析试验结果得出不同磨削参数对微磨削力和磨削温度影响规律。针对不同的磨削深度,研究微磨削表面温度和表面下不同深度位置的温度分布情况,并对加工表面进行热烧伤检测。根据试验数据结果对所建立微磨削力和微磨削温度的理论模型的准确性进行了验证,并通过试验测量得到微磨削后最高表面温度为78.5 ℃。试验研究结果也为进一步研究零件表面完整性和提高零件表面质量提供重要依据。     

花岗石磨削中的界面热特性分析

对垂直轴磨削花岗石和平面磨削花岗石加工过程中磨削弧区的温度场进行了理论解析，并采用铁-康铜热电偶测量了磨削弧区温度。通过将实际测量的温度结果与理论解析结果进行拟合得出了传入工件的能量比例。结果表明，垂直轴干磨削花岗石过程中磨削弧区内的花岗石表面的平均温度不超过100℃。工具与工件接触界面中约5l％的热量传入工件，其它的热量传到了树脂结合剂砂轮。在平面磨削花岗石的过程中，磨削弧区温度不超过120℃，工具与工件接触界面中约有3l％的热量传到工件，其它的热量传到了树脂砂轮。本文的研究结果对减小金刚石工具消耗，提高加工效率和石材表面质量有实际指导意义。     

平面磨削温度场有限元仿真及实验

在考虑不同磨削参数对温度场的影响的情况下,根据三角形热源模型对磨削工件进行了有限元仿真,获得了工件的温度分布。采用热电偶法测量了工件的磨削温度,发现有限元仿真值与实验测量值相当吻合,仿真结果能够真实反映工件的温度场。该有限元仿真方法对磨削过程中工件温度场的研究具有实际意义,为避免磨削烧伤提供了技术支持。     

陶瓷磨削温度对表面残余应力的影响

研究了磨削热对陶瓷表面残余应力的影响。采用夹式热电偶结构和高精度信号调理器测试陶瓷磨削温度，根据正交设计法测量的磨削温度实验结果说明：磨削温度随着磨削深度和砂轮速度的增加而提高；磨削深度ap=30μm是磨削残余应力和磨削温度曲线的转变点；磨削温度随着连续磨削次数的增加而增加，在磨削过程中磨削温度具有明显的累积效应。     

平面磨削温度及其对表面质量影响的实验研究

采用热电偶和三向测力仪分别测量了不同磨削条件下接触区的温度和力,并使用电子扫描显微镜和表面轮廓仪对已磨表面形貌和粗糙度进行了观测。实验表明,磨削参数对磨削温度有很大影响,同时磨削温度和实际接触长度相互影响。从切屑的形成机理和变形状态的角度出发,分析了顺磨时磨削温度高于逆磨时磨削温度的原因。讨论了磨削温度同已磨表面形貌及粗糙度之间的关系,结果发现,当磨削温度不足以使已磨表面出现明显烧伤时,磨削温度对表面粗糙度值的影响不大。     

防弹钢PRO500磨削过程有限元仿真与试验

对难加工材料防弹钢PRO500进行了有限元仿真分析,获得了这一材料的磨削温度分布。同时通过热电偶法对防弹钢PRO500进行了磨削温度测量,结果表明有限元仿真值与试验测量值吻合,确认磨削加工中水蒸气冷却相比低温气动喷雾冷却与常规乳化液冷却具有更好的效果。所做仿真与试验可以为防弹钢PRO500磨削过程中合理选择冷却方式、磨削参数提供参考。     

建筑石材磨削过程中的热特性分析

运用点热源叠加法理论对两种不同磨削方式加工过程中磨削弧区的温度场进行了理论解析.并采用夹丝热电偶法实际测量了磨削弧区温度.通过将实验结果与理论解析结果进行拟合得到了传入工件的能量与传入工具的能量百分比.研究结果表明,垂直轴干磨削花岗石过程中磨削弧区内的花岗石表面的平均温度不超过100℃.工具与工件接触界面中约51%的热量传入工件,其它的热量传到树脂结合剂砂轮.在平面磨削花岗石的过程中,磨削弧区温度不超过120℃,工具与工件接触界面中约有31%的热量传到工件,其它的热量传到了树脂砂轮.研究结果对减小金刚石工具消耗,提高加工效率和石材表面质量有实际指导意义.     

Variable heat flux in numerical simulation of grinding temperatures

In this paper, temperature results obtained by numerical simulations based on three different methods of defining the heat flux load distribution are compared to directly measured temperatures acquired using infrared camera measurement techniques. The heat flux calculations are based on recorded instantaneous grinding power, average grinding power, and power calculated by multiplying the measured tangential forces and the cutting velocity (referred to as calculated power). The results show that the method applied to characterize the input flux load in the numerical model has a significant effect on the estimated grinding temperatures and that the calculated power data produce the best temperature results.     

SG砂轮磨削航空合金温度研究

钛合金和高温合金的导热性差,磨削过程中产生的高温不仅加速砂轮的磨损,而且降低工件表面质量,磨削温度是影响磨削过程的重要参数。本文重点阐述了夹丝半人工热电偶法测温原理及标定方法,并对不同磨削条件下磨削航空合金的温度进行了实验研究。实验选用新型陶瓷氧化铝SG砂轮和普通GC砂轮,分析磨削温度信号的物理意义,系统地研究了磨削用量、磨削方式、砂轮类型以及工件材料对航空合金磨削时温度的影响,为航空合金的高效高精度磨削加工工艺优化提供实验依据。     

Analysis of temperature distributions in surface grinding with intermittent wheels

An analytical model was established to calculate the curve of temperature distributions in surface grinding with intermittent wheels. In order to predict the numbers of the pulses imposed on the fluctuating temperature profile, a new quantity, the dynamic number of wheel segments in the grinding zone, was defined. The temperatures at the grinding zone were measured by using a foil thermocouple. It is found that the new quantity, the dynamic number of wheel segments, can be used to accurately predict the pulses on the measured temperature curves in the grinding zone. Through matching the calculated temperature curves with the measured results, it is found that the temperature profile is greatly dependent on the wheel segment-engaging states even at identical grinding parameters. However, the wheel segment-engaging states have little influence on the values of peak and valley temperatures.     

TEMPERATURE AND ENERGY PARTITION IN HIGH-SPEED GRINDING OF ALUMINA WITH A BRAZED DIAMOND WHEEL

An investigation is reported on the temperatures and energy partitions for high speed grinding of alumina with a brazed diamond wheel. The grinding temperature at the wheel-workpiece interface was measured using a pair of grindable foil thermocouples. The energy partition to the workpiece was evaluated by matching the analytical temperatures to the measured results. The influences of the grinding conditions, including wheel speed, the depth of cut, workpiece velocity, and material removal rate, on the temperatures and energy partitions were investigated. In all tests, the maximum grinding zone temperature rise was below 260°C. The energy partitions to the workpiece obtained under different grinding conditions varied from 30% to 75%. The calculated diamond tip temperature might be over 1000°C if the circular grain contact radius of contact was less than a critical value.     

Determination of the Partition Coefficient for the Grinding of a Hard WC-Co-Cr Coating with a Diamond Wheel

□ Determination of the partition ratio is fundamental to a thermo-mechanical approach to the grinding process. To establish the energy balance, accurate measurements and numerical modelling must be combined. In this work, such a method is applied to the grinding of a HVOF WC-Cr-Co hard coating. A double pole grindable thermocouple was developed to measure the temperature in the arc of cut, and its effective length. The heat flux absorbed by the workpiece is found by fitting the numerical solution to the temperature profile measured during the cooling phase, behind the contact. Identical results for the heat flux may be obtained by fitting the results to the analytical solution from moving heat source theory, but the maximum interface temperature is underestimated. A finite element solution, using MSC Marc software allows a closer approach to the maximum temperature measured at the interface during grinding, provided that the thickness of the coating is correctly modelled.     

A study of the measurement of surface temperature at a cam/tappet contact

Cam/tappet wear is one of the most difficult reliability and durability problems to predict during the development of a prototype engine valve‐train system. In the present study, the cam/tappet surface temperature was measured and calculated to determine the effect of surface temperature on the lubricating conditions at a cam/tappet contact. The measurement method, sometimes called the dynamic thermocouple technique, was based on the Seebeck effect: by using different materials for the cam and tappet, the cam/tappet contact point becomes the hot junction of a ‘thermocouple’. The cam/tappet contact surface temperature can therefore be measured continuously. The measured temperature results show good agreement with predictions. Temperature spikes, however, were not found in the test using new oil, but were shown by the theoretical model. Such results indicate that the cam/tappet interface operates in effective lubricating conditions, even when the oil temperature is relatively high. Further research with degraded oil supplied at high temperature is needed for a thorough understanding of abnormal cam wear.     

Study on the convection heat transfer coefficient of coolant and the maximum temperature in the grinding process

Grinding fluid is typically applied in order to achieve reduced surface grinding temperatures, improved workpiece surface integrity, and extended wheel life compared to that which can be achieved in the dry situation. This paper presents the results of an investigation concerned with methods to determine the value of the convection heat transfer coefficient. The work is based on the theory of fluid dynamics and heat transfer that are used to describe the heat transfers within the grinding zone under different grinding conditions. The simulation research is made by means of the FEM for the wet grinding temperature distribution, and the three-dimensional topology map of the temperature distribution is obtained. Temperature is measured with the clamped thermocouple in different grinding conditions. The experimental result is approximately suitable to the simulated result. The simplicity and accuracy of the method allow the application to a wide range of grinding regimes from shallow-cut to high-efficiency deep grinding.     

An experimental investigation of temperatures and energy partition in grinding of cemented carbide with a brazed diamond wheel

An experimental investigation is reported of the temperatures and energy partition in the grinding of cemented carbide with a vacuum brazed diamond wheel. During the experiments, the temperature distributions along the workpiece surface were measured using a sandwiched foil thermocouples and the energy partition to the workpiece estimated using a temperature matching method. The effects of the various grinding conditions, including wheel velocity, feed rate, and depth of cut, on the temperatures and the energy partition were investigated. The measured temperature responses were found to be in good relation with the analytical results of a moving heat source with a triangular distribution at the grinding zone. It was found that the grinding temperatures measured under different grinding conditions varied from 10°C to 100°C. The energy partition to the workpiece in dry grinding was found to be from 35% to 70%. Based on the energy partition values obtained from the experiments, the diamond tip temperature was calculated and found to be over the temperature necessary for the graphitization of diamond if the circular grain contact of radius is smaller than a critical value.     

EXPERIMENTAL ANALYSIS OF TEMPERATURE IN GRINDING AT THE GLOBAL AND LOCAL SCALES

The purpose of the article is the experimental estimation of the global and local heat fluxes and the corresponding energy partition to the workpiece for regular grinding of 100Cr6 steel with aluminium oxide wheel. By using a grindable thermocouple, the temperature and the real contact length allow determination of the global heat flux and the partition ratio at the wheel scale. The high frequency analysis of the signal has shown maximum flash temperatures of about 1000°C corresponding to the local temperature under the chip-grain unit with very high heating speed of about 100°C/µs. The comparison between theoretical temperature decay and experimental cooling has demonstrated that the time response of the sensor is fast enough for the estimation of the local temperature and power due to the sliding of grain and to the plastic strain of ground materials.