Experimental and numerical study of the temperature field during creep feed grinding

In this study, commercially pure titanium sheets (American Society for Testing and Materials grade?2) were welded by resistance spot welding at various welding parameters. The welded joints were subjected to tensile-shearing tests in order to determine the strength values. In addition, the hardness and microstructural examinations were carried out in order to examine the influence of welding parameters on the welded joints. The experimental results showed that increasing electrode force, welding current and welding time increased the tensile-shearing strength of the welded specimens. Hardness measurement results indicated that welding nugget had the highest hardness and this was followed by the heat-affected zone and the base metal. Microstructural examinations showed the growth of the weld nugget grains with increasing heat input. Besides, due to plastic deformation during the welding process, twins were formed and at the same time twins increased with increasing electrode force, welding current and welding time.     

Numerical and experimental studies on the temperature field in precision grinding of SiCp/Al composites

During precision machining of SiCp/Al composites, the temperature of the workpiece surface directly affects the machining quality. In this paper, a triangle heat source model was used to calculate the heat flow during grinding of SiCp/Al composites, then, a three-dimensional finite element method was employed to investigate the temperature distribution at different process parameters, i.e., grinding depth and feed speed of the worktable. In addition, the temperature measures using embedded thermocouple were applied to compare with predictions from the thermal model. The results indicate that the grinding temperature predicted by the finite element method agrees well with the experiment data, and the triangle heat source model was suitable for estimating the workpiece temperature of precision grinding.     

Investigation of the grinding temperature and energy partition during cylindrical grinding

In this study, the distribution of temperature and energy under the process parameter conditions and thermal physical parameters are investigated using a physics-based model via the finite element modeling (FEM) simulation and experimental validation during cylindrical grinding. A cylindrical grinding model is modeled to simulate the chip removal behavior in the grinding process and to measure the workpiece and chip temperatures by refining the temperature field. Workpiece speed affects the energy partition into chip more obviously than other grinding parameters. Reasonable selection of grinding parameters greatly reduces the energy partition into the workpiece from 80% to 50–30% or even lower. This study offers a comprehensive understanding of heating mechanisms during grinding and thus is very beneficial for process optimization.     

On the temperature and specific energy during electrodischarge diamond grinding (EDDG)

Electrodischarge diamond grinding (EDDG) is a hybrid machining process comprising conventional grinding and electrodischarge machining (EDM) as its constituent processes. It has the potential of shaping advanced engineering materials. Temperature of the workpiece and material removal rate are chosen as responses in full factorial (3³) design with current, pulse-on time, and wheel speed as process parameters. Specific energy is a vital consideration for any machining process. EDM is known for its inefficiency. Experiments were conducted with a specially fabricated bronze disk as tool electrode to evaluate specific energy in EDM, and the results were compared with that of EDDG. It has been found that specific energy required in EDDG is less than that in EDM with a rotating disk electrode.     

A study of the temperature field during ultrasonic-assisted friction-stir welding

Ultrasonic-assisted friction-stir welding is a new solid-state metal welding technology, based on friction-stir welding, in which weld performance is improved through application of ultrasound during welding. In this study, a model for the temperature field in 1.8 mm 2024 aluminum alloy is built based on computational fluid dynamics and elastic-plastic mechanics theory. Result show the impact of the ultrasound’s vibrations on the temperature field is less obvious at lower welding speeds. However, at higher welding speeds, it can provide the additional heat to keep sufficient welding temperature. The numerical results are compared with optical micrographs in order to validate the numerical models. Good agreement is obtained.     

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。     

高速直齿轮本体温度场的仿真与试验研究

综合运用齿轮啮合学、摩擦学和传热学知识,精确计算了轮齿不同啮合位置的摩擦热流密度以及轮齿啮合面、端面的对流换热系数。利用ANSYS软件建立了直齿轮单个轮齿的有限元模型,获得了轮齿的本体温度场,分析了扭矩、转速以及润滑油输入温度等关键参数对轮齿本体温度场的影响。研究结果表明:轮齿最高温度区域分布在轮齿啮合接触面的中心部位,轮齿啮合面温度沿齿宽方向近似呈抛物线分布;轮齿的最高温度随扭矩、转速和润滑油输入温度的增加而增加;仿真值和试验值基本吻合,证明仿真分析方法可用于齿轮本体温度场的研究。     

薄片类零件平面磨削区表面温度场的计算研究

本文针对薄片零件平面磨削过程中表面温度与理论计算值存在偏差的问题,综合两种理论计算方法对薄片零件平面磨削区表面温度场的计算公式进行了修正,结合有限元分析的方法确定了未知参数,并验证了合理性.     

An experimental investigation of temperatures during conventional and CBN grinding

In many grinding applications, the material removal rate is constrained by the undesired thermal effects such as surface burn, tensile residual stresses, and micro-cracks on the ground parts. Thermal damage is a common productivity limitation factor for conventional grinding wheels largely employed in industry due to their convenient cost and known behavior. The development of superabrasive materials having high heat conduction coefficients allowed for higher material removal rates, pushing up the limits of productivity previously achieved with conventional wheels. This paper presents the results of a comparative investigation of maximum surface temperatures generated during the plunge grinding of 52100 steel using Al₂O₃ and CBN wheels. The experiments were conducted under wet as well as dry grinding conditions. The temperatures measured experimentally were compared to those determined analytically. A discussion relative to heat partition coefficients concludes this paper.     

圆环内孔磨削温度场的有限元仿真

运用传热学原理,结合圆环内孔磨削实际情况,并进行合理的简化和假设,建立了圆环内孔磨削的热传导数学模型,利用有限元分析软件ANSYS,对热传递过程进行了仿真,得出了工件内部温度场分布云图,进而分析了磨削过程中温度的分布及变化情况.模拟结果较真实的反映了圆环内孔磨削热状况,为解决圆环内孔磨削表面热损伤和热变形等问题提供了依据.     

钢轨CBN砂轮高速打磨试验台设计与试验研究

研制一种可模拟高速打磨实际工况的高速CBN砂轮打磨试验平台、该试验台可模拟砂轮纵向、垂向进给,并且可以实现±50°偏转,实现钢轨的正向、侧向的打磨。通过试验台模拟打磨试验验证了CBN砂轮高速打磨钢轨的可行性,并得出3#复合结合剂砂轮最适合高速打磨,最优打磨砂轮线速度70m/s^80m/s,最优下压力800N^1000N。     

纳米流体微量润滑磨削硬质合金温度场模型与实验验证

温度过高是目前磨削加工硬质合金的技术瓶颈。相比传统的干磨削工况,纳米流体微量润滑(NMQL)的冷却润滑方式是解决磨削热损伤的有效措施。为了验证纳米流体微量润滑工况下磨削硬质合金的可行性,建立了硬质合金的传热模型,并在此基础上对硬质合金的磨削温度场进行了数值仿真研究。对硬质合金(YG8)进行了不同工况下的表面磨削试验。结果表明,以干磨削工况下的磨削温度(227.2℃),微量润滑(MQL)工况和纳米流体微量润滑工况下磨削区温度分别降低了20.42%和39.48%。数值仿真温度与实验测量温度的误差为6.3%。从宏观参数(比磨削力、磨削温度)和微观参数(砂轮表面形貌)出发,研究了不同工况对砂轮磨损的影响。实验结果,进一步证明纳米流体微量润滑适用于硬质合金的磨削加工。     

On the formation of a quick-stop chip during single grit grinding

An experimental method is described for the provision of quick-stop chips in an authentic grinding grit-workpiece situation. Metallographical and scanning electron microscopical examinations of the chips have provided information to aid the elucidation of the mechanism of metal removed during grinding with abrasive particles having large negative rake angles.     

Temperature field model and experimental verification on cryogenic air nanofluid minimum quantity lubrication grinding

Considering the poor lubricating effect of cryogenic air (CA) and inadequate cooling ability of nanofluid minimum quantity lubrication (NMQL), this work proposes a new manufacturing technique cryogenic air nanofluid minimum quantity lubrication (CNMQL). A heat transfer coefficient and a finite difference model under different grinding conditions were established based on the theory of boiling heat transfer and conduction. The temperature field in the grinding zone under different cooling conditions was simulated. Results showed that CNMQL exerts the optimal cooling effect, followed by CA and NMQL. On the basis of model simulation, experimental verification of the surface grinding temperature field under cooling conditions of CA, MQL, and CNMQL was conducted with Ti–6Al–4V as the workpiece material. Simultaneously, CNMQL exhibits the smallest specific tangential and normal grinding forces (2.17 and 2.66 N/mm, respectively). Further, the lowest grinding temperature (155.9 °C) was also obtained, which verified the excellent cooling and heat transfer capabilities of CNMQL grinding. Furthermore, the experimental results were in agreement with theoretical analysis, thereby validating the accuracy of the theoretical model.     

基于 DEFORM－3D 的固体润滑涂层对磨削温度场的影响仿真研究

针对磨削过程中产生的大量磨削热容易导致磨削灼伤的问题,进行了固体润滑涂层对磨削温度场影响的仿真研究。基于DEFORM－3D有限元仿真软件,模拟了电镀CBN砂轮高速磨削TC4钛合金的过程,比较了电镀CBN砂轮在有无固体润滑软涂层的条件下高速磨削TC4钛合金时温度场的变化规律。研究结果表明,固体润滑涂层应用于高速磨削中,可有效降低磨削温度,避免磨削灼伤。     

An experimental study on grinding parameters for manufacturing PCD micro-milling tool

Micromachining has become a necessary manufacturing process. Micro-milling tool and its evolution play a vital role in the development of micromachining. This study optimizes the grinding process of polycrystalline diamond (PCD) compact for manufacturing PCD micro-tool. The optimization is conducted by using four parameters, i.e., grain size of PCD compact, grain size of abrasive wheel, grinding speed, and feed rate designed by the Taguchi orthogonal array. The study then evaluates two grinding characteristics, i.e., grinding forces and cutting edge radius of the PCD compact. The results of ANOVA show that the most influential parameter on grinding PCD compact is the grain size of the PCD compact, followed by the grain size of the abrasive wheel, feed rate, and grinding speed. As an example, a quadrilateral PCD micro-milling tool with a cutting edge diameter of 80 μm is fabricated by using the optimized parameters.     

平面二次包络四轴四联动数控磨床加工原理及实验研究

分析了平面二次包络四轴四联动数控磨床的加工原理,根据该原理及磨床结构建立了坐标系,推导出了各个相对坐标系间的齐次坐标变换矩阵,创建了理论状态下的数控加工数学模型,并采用基于CDK6150数控车床改造的平面二次包络四轴四联动数控磨床进行切削实验,设置平面二次包络蜗杆参数,编写数控加工程序,验证了其加工原理的正确性.