FORCES AND TEMPERATURES IN HARD TURNING

In precision machining, due to the recent developments in cutting tools, machine tool structural rigidity and improved CNC controllers, hard turning is an emerging process as an alternative to some of the grinding processes by providing reductions in costs and cycle-times. In industrial environments, hard turning is established for geometry features of parts with low to medium requirements on part quality. Better understanding of cutting forces, stresses and temperature fields, temperature gradients created during the machining are very critical for achieving highest quality products and high productivity in feasible cycle times. To enlarge the capability profile of the hard turning process, this paper introduces prediction models of mechanical and thermal loads during turning of 51CrV4 with hardness of 68 HRC by a CBN tool. The shear flow stress, shear and friction angles are determined from the orthogonal cutting tests. Cutting force coefficients are determined from orthogonal to oblique transformations. Cutting forces, temperature field for the chip and tool are predicted and compared with experimental measurements. The experimental temperature measurements are conducted by the advanced hardware device FIRE-1 (Fiberoptic Ratio Pyrometer).     

内调制光纤比色温度传感器

本文简要地介绍了一种新型的内调制光纤比色温度传感器。这种传感器是利用我们提出的内调制微光技术研制而成,其目的在于解决冶金等行业中高温辐射体的在线测量,为产品质量控制提供必要条件。     

陶瓷刀具在精密轧辊硬车削加工中的应用

在论述硬车削及其加工优点的基础上,提出了在精密轧辊加工中采用硬车削取代磨削的方法。通过对陶瓷刀具的选用、加工机床的选用、刀具结构、刀具切削用量等方面的优化配置,可以实现精密轧辊的加工要求。试验表明,陶瓷刀具在精密轧辊硬车削加工中的应用效果良好。     

高温光纤压力传感器的设计

介绍了一种高温光纤压力传感器的设计。并详细介绍了传感器的结构、工作原理以及信号 检测电路。     

INDUCTION-HEATED TOOL MACHINING OF ELASTOMERS—PART 1: FINITE DIFFERENCE THERMAL MODELING AND EXPERIMENTAL VALIDATION

Experiments and finite difference thermal modeling of the induction-heated tool for end milling of elastomers are investigated. Three sets of experiments are designed to calibrate the contact thermocouple for the tool tip temperature measurement, study the effect of tool rotational speed on induction heat generation and convective heat transfer, and measure the tool temperature distribution for finite difference inverse heat transfer solution and validation of modeling results. Experimental results indicate that effects of tool rotation on induction heat generation and convective heat transfer are negligible when the spindle speed is below 2000 rpm. A finite difference thermal model of the tool and insulator is developed to predict the distribution of tool temperature. The thermal model of a stationary tool can be expanded to predict the temperature distribution of an induction-heated rotary tool within a specific spindle speed range. Experimental measurements validate that the thermal model can accurately predict tool tip peak temperature.     

INDUCTION-HEATED TOOL MACHINING OF ELASTOMERS—PART 1: FINITE DIFFERENCE THERMAL MODELING AND EXPERIMENTAL VALIDATION

ABSTRACT

Experiments and finite difference thermal modeling of the induction-heated tool for end milling of elastomers are investigated. Three sets of experiments are designed to calibrate the contact thermocouple for the tool tip temperature measurement, study the effect of tool rotational speed on induction heat generation and convective heat transfer, and measure the tool temperature distribution for finite difference inverse heat transfer solution and validation of modeling results. Experimental results indicate that effects of tool rotation on induction heat generation and convective heat transfer are negligible when the spindle speed is below 2000 rpm. A finite difference thermal model of the tool and insulator is developed to predict the distribution of tool temperature. The thermal model of a stationary tool can be expanded to predict the temperature distribution of an induction-heated rotary tool within a specific spindle speed range. Experimental measurements validate that the thermal model can accurately predict tool tip peak temperature.     

提高分布式光纤温度传感器测量准确性的方法

分布式光纤温度传感技术是近年来发展起来的一种新型传感技术,它利用一根光导纤维作为温度信息的传感和传导介质,可以测量整个光纤长度上的温度情况。这在解决大型重要结构的实时监控、准确测量等问题以及在组成智能材料结构等方面具有重要价值和应用潜力。本文对基于反斯托克斯／斯托克斯比值的分布式光纤温度传感器系统的温度计算方法和定标进行了理论分析,并提出了采用计算方法消除两路测量通道的损耗系数差异对温度测量的影响。     

声学法工业炉温度场检测技术综述

对声学法工业炉温度场检测技术进行了综述。包括声学法工业炉温度场检测系统的构成、基本工作原理、国内外研究应用现状，分析了声学法在工业炉温度场检测中需要解决的一些问题，肯定了其具有的优越性能，并对其发展前景进行了展望。     

FINITE DIFFERENCE METHOD-BASED SIMULATION OF TEMPERATURE FIELDS FOR APPLICATION TO ORTHOGONAL CUTTING WITH COATED TOOLS

A finite difference method was proposed to model the effect of a variety of tool coatings on the magnitude and distribution of temperatures through the tool-chip contact region and the coating/substrate boundaries. For each workpiece-tool pair tested the intensity of uniformly distributed heat flux and relevant analytically obtained values of the heat partition coefficient were assumed to change with variations of cutting speed and the corresponding friction. In this case the simulation of an orthogonal machining of AISI 1045 steel was performed using special computing algorithm with elementary balances of induced energies (MBE). It is concluded that the temperature contours obtained reflect favorable the specific contact conditions existing at the tool-chip interface and substantial differences can arise from coating effects.     

高精度转向节销的数控车削加工

介绍了在林德－厦门合资叉车产品的国产化过程中，为满足一种高强度，高精度转向节销的数控车削加工的要求所提出的加工方案，工装的配置，设备选型以及采取的措施，采用该方案，成功地实现了这种零件部的高精率批量数控车削加工，提高了加工效率，并节省了设备投资。     

Temperature control in CBN grinding

The main advantage of CBN grinding wheels is the long wheel life owing to the hardness of the CBN abrasive. Recent research has confirmed another advantage of CBN, which is cooler grinding. The new research allows the temperature in grinding to be predicted based on experimentally validated CBN thermal properties. This work also provides for in-process prevention of thermal damage in grinding. A well-documented feature of CBN grinding is the reduced risk of thermal damage to the workpiece. This advantage can allow a marked increase in removal rate whilst maintaining surface quality of the component compared to grinding with conventional abrasives such as aluminium oxide. The reduced risk of thermal damage in CBN grinding is sometimes attributed to the lower grinding specific energies. While lower specific energies when achieved are an advantage, this explanation ignores a fundamental advantage of the CBN abrasive. The experimental investigation has shown that a major advantage of CBN grinding is that a substantially lower proportion of the total grinding energy enters the workpiece compared to grinding with alumina wheels. The results further indicate that the effective thermal conductivity of CBN grains is considerably lower than its reported theoretical value of 1300 W(mK)^–1.     

CO_2气体浓度光纤传感器研究

文中研究了基于光纤扰模的气体浓度传感器的传感机理。研制了CO2 气体光纤传感器 ;并进行了CO2 气体传感实验研究 ,结果表明该传感方法是可行的。该气体传感器结构简单 ,在工业及科研等方面有广泛的实用价值。     

光纤陀螺的时变梯度场效应

给出了时变梯度场对光纤陀螺输出的影响,并给出了实验结果。     

热喷涂镍基合金粉末表面的车削加工

在大型灰口铸铁件表面用镍基合金粉末热喷涂处理后，为保证零件的尺寸精度和形位公差精度符合设计要求，采用了以车代磨加工方法。文章主要介绍了PCBN刀具在该加工中的应用。并从增强刀具的抗冲击性能和延长刀具寿命、降低生产成本等方面作了初步探讨。实践证明该方法是行之有效的。     

电镀CBN锥砂轮磨齿热状态的研究

通过对磨齿过程中砂轮与工件系统的分析 ,建立了锥砂轮磨齿热状态分析模型 ,并分别运用一维传热杆模型及有限单元法分析、计算了磨削所引起的齿面表层的温度场 ;同时 ,用电镀CBN、陶瓷CBN和刚玉砂轮做模拟磨齿试验 ,考察了不同的砂轮及工艺参数对齿面温度的影响。结果表明 ,试验结果与计算结果基本吻合 ,电镀CBN锥砂轮磨削所引起的齿面温升仅是刚玉砂轮的 5 0 % ,比陶瓷CBN砂轮亦低。     

光纤陀螺零偏稳定性研究

以简明的方法推导了干涉型光纤陀螺零偏稳定性表达式,并讨论了它们的适用范围和局限。     

Tool crater wear depth modeling in CBN hard turning

Hard turning has been receiving increased attention because it offers many possible benefits over grinding in machining hardened steel. The wear of cubic boron nitride (CBN) tools, which are commonly used in hard turning, is an important issue that needs to be better understood. For hard turning to be a viable replacement technology, the high cost of CBN cutting tools and the cost of down-time for tool changing must be minimized. In addition to progressive flank wear, microchipping and tool breakage (which lead to early tool failure) are prone to occur under aggressive machining conditions due to significant crater wear and weakening of the cutting edge. The objective of this study is to model the CBN tool crater wear depth (K_T) to guide the design of CBN tool geometry and to optimize cutting parameters in finish hard turning. First, the main wear mechanisms (abrasion, adhesion, and diffusion) in hard turning are discussed and the associated wear volume loss models are developed as functions of cutting temperature, stress, and other process information. Then, the crater wear depth is predicted in terms of tool/work material properties and process information. Finally, the proposed model is experimentally validated in finish turning of hardened 52100 bearing steel using a low CBN content tool. The comparison between model predictions and experimental results shows reasonable agreement, and the results suggest that adhesion is the dominant wear mechanism within the range of conditions that were investigated.     

双辉等离子渗金属中的光电高温计测温研究

分析比较了几种应用在双辉等离子渗金属中的测温手段存在的问题，指出了准确控制工件温度的重要性。为准确测量出工件温度，借助自制的一套热电偶测温实验装置，对光电高温计测温进行了比对实验，探讨了工件温度、保温时间等工艺参数对光电高温计测温精度的影响。实验结果表明：在双辉等离子渗金属过程中，光电高温计测温过程分动态和稳态两个阶段；对不同的工件温度，应用不同的ε值来测量。