Nd-Fe-B烧结永磁材料的车削加工研究

对Nd-Fe-B烧结永磁材料的车削加工进行了试验研究。用线性断裂力学的方法建立了硬脆材料车削加工时的材料去除模型。探讨了车削过程中背吃刀量、进给量和车削速度对车削力及加工表面质量的影响，采用多元回归分析方法得出了主车削力的经验公式，并给出了用于检验回归结果与试验结果符合程度的误差评判参数。分析了Nd-Fe-B烧结永磁材料车削过程中刀具的磨损状况，以及刀具几何参数对加工质量的影响。     

精密硬车加工轴承套圈的表面完整性试验研究

针对磨削加工中套圈精密加工存在的不足,进行精密硬车削加工轴承套圈新工艺的开发,通过加工试验分析了精密硬车加工轴承套圈的表面完整性,探究了基准面平面度、刀具磨损量等工艺参数与加工精度的对应关系。基于精密硬车削套圈试样的表面粗糙度、沟道圆度、显微硬度、热损伤、金相组织、残余应力分布、加工效率等方面的研究,得出了精密硬车削可达到磨削加工精度的结论,且金相组织稳定,不易存在热损伤,具有可控的残余应力分布和较高的加工效率,有利于产业化生产高精密轴承。利用磁性卡盘装夹套圈,分析试样基准面平面度对精密硬车削套圈沟道圆度的影响,发现提高基准面平面度可以有效提高加工套圈的沟道圆度;分析了刀具磨损对硬车削套圈加工精度的影响,得出在精密加工阶段刀具磨损量是控制套圈圆度的重要监控工艺参数的结论。     

基于Deform的旋转车削与硬车削对比

介绍了一种新型加工技术——旋转车削,根据其加工特点提出有限元模型,并用有限元软件对旋转车削和硬车削进行模拟仿真,重点对比分析其等效应变、等效应变率、等效应力和温度。结果表明:在进给量相同的情况下,旋转车削模拟时产生的最大等效应变和最大等效应变率远远小于硬车削的相应参数;两者的最大等效应力比较接近;硬车削模拟时产生的最高温度不仅大于旋转车削,而且在进给量≥0.4mm时,最高温度超过其许用温度,这可视为在切削参数相同时,硬车削所加工的工件表面粗糙度值大于旋转车削。     

特大型调心滚子硬车削工艺试验探究

以某型风电轴承用特大型调心滚子为试验对象,制定硬车削工艺流程,在高精密数控机床上进行硬车削工艺试验.通过对硬车削和传统磨削两种工艺加工产品检测数据进行对比分析,验证了特大型滚子采用硬车削工艺加工的优势和可行性.     

激光加热辅助车削淬硬钢的白层形成临界切削速度预测与实验研究

淬硬钢已加工表面极易产生白层,对零件的服役性能造成很大影响,采用激光加热辅助车削替代常规车削来加工淬硬钢可解决白层形成的问题.利用VDFLUX用户子程序建立了热力耦合移动激光加热辅助车削过程有限元模型并进行仿真.基于有限元模型仿真结果和白层形成临界切削速度预测模型,分析了不同激光预热参数对白层形成临界切削速度的影响.结...     

硬车削滚动轴承套圈的试验研究

针对滚动轴承套圈硬车削加工过程中表面质量存在的问题,对硬车削过程中切削用量和刀具参数对表面粗糙度的影响进行了研究,采用CBN刀具进行了6205滚动轴承套圈的硬车削加工试验,将进给量、切削速度、切削深度和刀尖圆弧半径作为试验因子,通过正交试验分析了它们对零件加工后表面粗糙度的影响规律,并归纳出了该试验范围内的最佳切削用量和刀具参数组合。研究结果表明,进给量对表面粗糙度的影响最大,刀尖圆弧半径对表面粗糙度的影响次之,切削速度对表面粗糙度的有一定影响,切削深度对表面粗糙度的影响非常小。     

金刚石刀具几何参数对已加工表面残余应力的影响

针对微米级切削深度的超精密车削中金刚石刀具几何参数对已加工表面残余应力的影响,采用有限元的方法,建立超精密车削的有限元仿真模型,对硬铝合金的超精密车削过程进行模拟。对车削过程的切削力和切削温度进行分析。采用不同的刀具几何参数进行有限元仿真,得到刀具前角、后角和钝圆半径对已加工表面残余应力的影响和分布规律,为超精密车削中残余应力的控制提供仿真依据。     

硬车削及其加工技术

本文论述了硬车削加工的特点，硬车削加工所需的条件，分析了硬车削应用不广的原因，指出硬车削是一种高效洁净的工艺方法，具有广泛的应用前景。     

硬车削及其加工技术

介绍了硬车削加工的特点，硬车削加工所需的条件；分析了硬车削应用不广的原因，指出硬车削是一种高效洁净的工艺方法，具有广阔的应用前景。     

硬车削技术及其应用

分析了硬车削加工的特点、硬车削加工所需的条件以及硬车削技术在生产中的应用，并对其关键技术进行了探讨，指出硬车削技术是一种高效、洁净的工艺方法，具有广泛的应用前景。     

Surface Integrity and Machineability in Intermittent Hard Turning

Despite the large amount of research on hard turning, there are few results on intermittent hard turning. In this paper, the feasibility of internal intermittent hard turning has been investigated. First, the cutting tools with different cubic boron nitride (CBN) contents were evaluated, based on machineability: tool wear, surface roughness, and cutting forces. In the case of intermittent turning, low CBN content tools had better machineability than high CBN content tools. The depth of the machining damaged layer and the magnitude and distribution of residual stress were evaluated. The experimental results showed that intermittent hard turning can produce surface integrity which is good enough for replacing the grinding process.     

Air–Oil Cooling Method for Turning of Hardened Material

The hard turning process, defined as single-point turning of materials harder than HR C 58, differs from conventional turning because of the hardness of the work materials and cutting tools needed in the process. In hard turning, tool life is very short, of the order of a few minutes, during which time the cutting tool is subjected to extreme stress and tempera-ture. In this regard, it is well known that CBN tools are well suited for this process despite their high cost. In this research, we studied the feasibility of using lower-cost cutting tools such as TiN coated tools. To this end, a new cooling system was designed using an air–oil method, which is based on the principle of air vortex flow, for reducing tool temperature. In this system, the temperature of air at the outlet is lowered by more than 20°C using pressurised air of 5 kgf cm −2 at the inlet. The cooled air ejected at the tip of the cutting tool lowers tool temperature, and reduces the wear of a TiN coated tool to give 30% of CBN tool life with respect to the same cutting length.     

Environmentally conscious hard turning of cemented carbide materials on the basis of micro-cutting in SEM: stressing four kinds of cemented carbides with PCD tools

Environmentally conscious hard turning and technology has placed more importance on the machining process. In this research, the possibility of environmentally conscious hard turning of cemented carbides was studied. The effects of cutting methods of dry and wet (vegetable oil mist, and mineral oil) and work material on cutting resistance and wear characteristics of cutting tools were experimentally investigated. The turning and micro-cutting process in SEM was carried out by using four kinds of tungsten carbides with the PCD cutting tools. Specifically, an emphasis was put on the effect of WC and Co additives in four kinds of cemented carbides on machinability and tool wear characteristics. The tool wear width and the cutting resistances were measured, and the worn flank was observed.     

Study on cutting force and surface micro-topography of hard turning of GCr15 steel

This work investigates the cutting force and surface micro-topography in hard turning of GCr15 bearing steel. A series of experiments on hard turning of GCr15 steel with polycrystalline cubic boron nitride (PCBN) tools are performed on a CNC machining center. Experimental measurements of cutting force, 3D surface micro-topography, and surface roughness of the workpiece are performed. The 3D surface micro-topography of the workpiece is discussed, and the formation mechanism of the 3D surface is analyzed. The influence of cutting speed and feed rate on cutting force and surface roughness are discussed. The 2D and 3D surface roughness parameters are compared and discussed. It is found that feed rate has greater influence on cutting force and surface roughness than cutting speed and there exists the most appropriate cutting speed under which the minimum surface roughness can be generated while a relatively small cutting force can be found. Recommendations on selecting cutting parameters of hard turning of GCr15 steel are also proposed.     

On the finite element modelling of high speed hard turning

The results reported in this paper pertain to the simulation of high speed hard turning when using the finite element method. In recent years high speed hard turning has emerged as a very advantageous machining process for cutting hardened steels. Among the advantages of this modern turning operation are final product quality, reduced machining time, lower cost and environmentally friendly characteristics. For the finite element modelling a commercial programme, namely the Third Wave Systems AdvantEdge, was used. This programme is specially designed for simulating cutting operations, offering to the user many designing and analysis tools. In the present analysis orthogonal cutting models are proposed, taking several processing parameters into account; the models are validated with experimental results from the relevant literature and discussed. Additionally, oblique cutting models of high speed hard turning are constructed and discussed. From the reported results useful conclusions may be drawn and it can be stated that the proposed models can be used for industrial application.     

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).     

硬切削AISI 440C不锈钢切削力建模及试验分析

利用四种不同形状的刀具,采用多因素正交试验的方法,对四种不同硬度的AISI440C不锈钢进行干硬切削。基于多因素正交回归方法,建立了AISI44C不锈钢的切削力经验模型,并对方程进行了显著性检验。通过对方程的研究,分析了切削参数对切削力的影响。     

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).     

Environmentally conscious hard turning of cemented carbide materials on the basis of micro-cutting in SEM (2nd report): stress turning with three kinds of cutting tools

Environmentally conscious hard turning and technology have placed increasing importance on the machining process. Cutting fluids have a significant impact on the environment, thus numerous research works are being performed to minimize their use. However, tool wear is very severe in hard turning cemented carbides without the use of cutting fluids. In this research, the effects of dry and wet cutting methods (vegetable oil mist and mineral oil) and tool material on cutting resistance and wear characteristics of cutting tools were experimentally investigated to study the possibility of creating an environmentally conscious hard turning of cemented carbides. Mist and wet cutting of the cemented carbides using poly-crystalline diamond (PCD) cutting tools were adopted to investigate how tool wear on the basis of micro-cutting in the Scanning Electron Microscope (SEM) can be reduced. Additionally, the poly-crystalline cubic boron nitride (PcBN) and the usual cBN cutting tools were compared with the PCD cutting tools. This paper was presented at the 9^th Asian International Conference on Fluid Machinery (AICFM9), Jeju, Korea, October 16–19, 2007.recommended for publication in revised form by Associate Editor Dae-Eun Kim HEO Sung Jung was born in Busan, R. O. K., in 1958. He received the Ph.D. in Mechanical Engineering from Osaka University, Osaka, Japan. He is a Full Professor of Mechanical Engineering at Doowon Technical College, Ansong -si, Gyonggi-do, Republic of Korea. His current research interests are in the areas of cutting of difficult-to-cut materials, environmentally conscious machining and cutting tool design.