开槽砂轮缓进给深切磨削时工件表层温度场解析

采用热源法推导出开槽砂轮缓进给深切磨削时磨削弧区工件表层温度分布的理论解析式，并利用理论计算公式结合磨削实验完成了施加水射流冲击条件下工件表层温度场的推演计算，计算结果与实验结果基本吻合，证实了开槽砂轮辅以弧区定向高压水射流冲击强化换热的确具有良好的冷却效果。     

断续磨削温度场的研究

在分析普通磨削和断续磨削温升特点的基础上推导出新的断续磨削温度场解析式,在分阶段析磨削温度时,考虑了冷却液的影响。通过电算,从理论上分析了砂轮沟槽几何参数η和冷却散热系数H对磨削温度影响的规律。试验验证了理论分析的正确性。文中所建立的磨削热模型亦有助于分析诸如铣削、断续切削等其他机械加工中产生的热问题。     

磨削温度场的数值计算

本文对不同导热模型下的4种磨削温度场计算式进行了简化，用简化后的计算式对磨削温度场进行数值计算，并验证了计算结果的准确性，发现按热源强度均匀分布计算出的磨削温度场更接近实际。     

冷作磨具钢Cr12MoV磨削温度场解析模型的建立

磨削温度的研究一直是磨削领域的重点课题,磨削热可能导致零件表面出现热损伤。针对冷作磨具钢Cr12MoV磨削接触区的温度场进行了理论分析,利用热源法建立了磨削温度场的数学模型,并对此温度场的计算机仿真模型进行分析。     

磨削温度场的科学计算可视化研究

论述了科学计算可视化的概念,介绍了科学计算可视化的分类与方法。并利用VisualC 开发平台,对平面磨削力和磨削温度场模型进行了科学计算,用OpenGL工具建立了工件的三维实体模型,并在工件实体上用不同的颜色表示不同温升值,从而实现了磨削温度场的可视化过程。同时,系统可以给出磨削温度场中各点的温升值,以及表面温度场曲线和深度方向的温度曲线。     

超声振动磨削陶瓷的温度场特性研究

采用人工热电偶法,通过普通磨削和超声振动磨削对比实验,对陶瓷材料ZrO2平面磨削的温度场进行了实验研究。并对磨削参数与磨削温度的关系,进行了理论分析及实验验证。结论表明:距磨削表面越远,其磨削温度的峰值越远离热源;增大磨削深度、提高磨削速度和工作台进给速度都会使工件表面温度升高。正交试验表明,磨削深度对温度场的影响较大。普通磨削时工件表层的温度较高,易发生磨削烧伤,采用超声复合磨削能有效降低工件表层温度。     

面齿轮磨削温度场分析

基于蜗杆砂轮磨削面齿轮原理和空间曲面理论,推导了面齿轮齿面磨削点处主曲率和主方向计算公式;基于瞬时椭圆接触理论和磨削热理论,建立了面齿轮磨削温度场理论公式;基于ANASY建立面齿轮磨削温度场有限元模型,完成了磨削温度场有限元仿真;设计完成了磨削温度场实验,验证了有限元法的正确性;基于正交试验法,研究了磨削工艺参数对齿面温度分布的影响规律。     

平面磨削温度场三维有限元仿真及其实验研究

在考虑工件材料物理性能与温度的非线性关系情况下,采用三角形热源模型对一些典型的磨削工况进行了三维有限元仿真,获得了工件的温度分布.采用热电偶法测量了磨削温度,发现有限元仿真值与实验测量值相当吻合,仿真结果能够真实地反映工件的热状况.     

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。     

蜗轮稳态温度场及有限元分析

通过蜗杆传动的传热学、摩擦学及啮合原理的结合上进行研究,建立了蜗轮稳态温度场的数学模型。对对流换热系数和齿面输入的热流密度进行了分析,针对蜗轮齿面的几何特征和运动特征研制了相应的有限元程序,计算结果与实测结果基本一致。这为研究蜗轮的胶合失效和热弹流问题提供了依据。     

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.     

TEMPERATURE DISTRIBUTION DURING ELECTRO-DISCHARGE ABRASIVE GRINDING

The objective of this work is to develop a finite element method (FEM) based mathematical model to simulate the hybrid machining process of grinding and electric discharge machining (EDM), named as Electro-discharge abrasive grinding (EDAG), for temperature distribution in the workpiece. Two different finite element codes have been developed to calculate the temperature distribution due to grinding heat source and EDM heat source separately. The transient temperature field within workpiece due to cut-off grinding is determined due to moving rectangular heat source. Gaussian heat distribution of power within a spark has been considered in the calculation of temperature distribution due to EDM. Temperature distribution in the workpiece due to combined process is obtained by using superposition. The simulation shows a sudden rise in temperature at the spark location. The predicted results can be used for calculation of thermal stresses, which play a major role as far as high-quality product requirements are concerned.     

TEMPERATURE DISTRIBUTION DURING ELECTRO-DISCHARGE ABRASIVE GRINDING

The objective of this work is to develop a finite element method (FEM) based mathematical model to simulate the hybrid machining process of grinding and electric discharge machining (EDM), named as Electro-discharge abrasive grinding (EDAG), for temperature distribution in the workpiece. Two different finite element codes have been developed to calculate the temperature distribution due to grinding heat source and EDM heat source separately. The transient temperature field within workpiece due to cut-off grinding is determined due to moving rectangular heat source. Gaussian heat distribution of power within a spark has been considered in the calculation of temperature distribution due to EDM. Temperature distribution in the workpiece due to combined process is obtained by using superposition. The simulation shows a sudden rise in temperature at the spark location. The predicted results can be used for calculation of thermal stresses, which play a major role as far as high-quality product requirements are concerned.     

NUMERICAL SIMULATION AND EXPERIMENTAL VALIDATION OF THE TEMPERATURE FIELD IN SURFACE GRINDING

Three-dimensional numerical simulations are carried out to investigate the temperature field in the contact zone due to the thermal loading of the workpiece in surface grinding. This technique considers that the thermophysical properties of the workpiece material are non-linear according to temperature, the contact zone between the wheel and the workpiece is assumed as an arc surface, and the heat flux entering the workpiece is assumed as proportional to the local undeformed chip thickness. A good agreement is found between the simulated results and the experimental observations. The high grinding temperature leads to the thermal expansion of the workpiece material, which causes the thickness of the actual material removal layer to be larger than the cutting depth. The grinding temperature at the central portion is higher than that on the side of the workpiece during the wet grinding, thus the material removal layer in the central zone is thicker than that on the side zone, and the workpiece surface is concave across the grinding width.     

INVESTIGATION OF SURFACE TEMPERATURE IN HIGH-EFFICIENCY DEEP GRINDING

A new thermal model with triangular heat flux distribution is given in high-efficiency deep grinding.The mathematical expressions are driven to calculate the surface temperature.The transient behavior of the maximum temperature on contact area is investigated in different grinding conditions with a J-type thermocouple.The maximum contact temperatures measured in different conditions are found to be between 1 000℃ and 1 500℃ in burn-out conditions.The experiment results show good agreement with the new thermal model.     

电热爆炸喷涂层温度场的数值模拟

涂层／基体的结合强度取决于涂层与基体间的热接触作用,尤其是第一层涂层与基体的相互作用。分析电热爆炸喷涂层的温度场特点,建立温度场模型,并对不锈钢基体上电热爆炸喷涂Al涂层进行了温度场的有限元数值模拟。给出了涂层和基体温度场随时间的变化规律。分析不同界面热阻对温度分布以及凝固过程的影响。结果表明涂层组织将在基体表面由于快速凝固而得到细化,仿真结果对于试验具有一定的指导意义。     

COMPARISON AND ANALYSIS OF THREE DIFFERENT NON－CONTACTING FLAME TEMPERATURE FIELD MEASUREMENTS

A much better substitutional means is discussed to calculate the flame temperature field with the application of digital image processing technology. Three non-contacting temperature measurements are used and compared. Such as the traditional two-color temperature measurement,the CCD filtering two-color temperature measurement and the monochromatic temperature measurement. It is indicated that the CCD two-color temperature measurement is not a fully correct means because of its poor theoretical basis. The monochromatic temperature measurement acquires a relatively ideal temperature field distribution in spite of needing a reference temperature. It should be noted that the Abel transformation applied in the plasma diagnosis is for the first time introduced to solve the problem of three-dimensional flame brightness piling.     

基于有限元法的湿式磨削温度场分析

运用有限元法建立了湿式磨削温度场的数学模型,并借助于计算机对磨削温度场进行了仿真,得出了湿式磨削温度场的等温图。与解析解相比,有限元法具有更高的精度,更少的计算量及更广的应用范围。     

平面磨削颤振试验研究

首先,通过平面磨削过程动力学模型,对平面磨削颤振的发生和发展进行分析。然后,设计平面磨削颤振的试验方案,获得磨削颤振和磨削表面波纹度的试验结果,进而研究不同的磨削条件对磨削颤振和磨削表面波纹度的影响,得到与理论分析一致的结果。最后,给出磨削颤振和磨削表面波纹度之间的相互关系,研究表明,在平面磨削过程中,磨削深度是影响磨削颤振和磨削表面波纹度的主导因素;在较大的磨削深度条件下,磨削颤振的幅值和磨削表面的波纹度幅值随着工件速度的增加有显著增大的趋势。