共查询到20条相似文献,搜索用时 15 毫秒
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Fuzeng Wang Jun Zhao Anhai Li Hongxia Zhang 《The International Journal of Advanced Manufacturing Technology》2014,73(1-4):137-146
In the present study, high-speed side milling experiments of H13 tool steel with coated carbide inserts were conducted under different cutting parameters. The microhardness and microstructure changes of the machined surface and subsurface were investigated. A finite element model, taking into account the actual milling process, was established based on the commercial FE package ABAQUS/Explicit. Instantaneous temperature distributions beneath the machined surface were analyzed under different cutting speeds and feed per tooth based on the model. It was found that the microhardness on the machined surface is much higher than that in the subsurface, which indicates that the surface materials experienced severe strain hardening induced by plastic deformation during the milling process. Furthermore, the hardness of machined surface decreases with the increase of cutting speed and feed per tooth due to thermal softening effects. In addition, optical and scanning electron microscope (SEM) was used to characterize the microstructures of cross sections. Elongated grains due to material plastic deformation can be observed in the subsurface, and white and dark layers are not obvious under present milling conditions. The thickness of plastic deformation layer beneath the machined surface increases from 3 to 10 μm with the increase of cutting speed and feed per tooth. The corresponding results were found to be consistent and in good agreement with the depth of heat-affected zone in finite element analysis (FEA). 相似文献
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钛合金高速铣削表面完整性研究 总被引:2,自引:0,他引:2
研究了钛合金TC4的高速铣削。着重讨论了高速铣削钛合金TC4已加工表面完整性的问题,重点研究了表面粗糙度、表面变质层等因素对表面完整性的影响。研究结果表明,切削速度在v=200~350m/min范围,钛合金TC4高速铣削获得的加工表面完整性较好。 相似文献
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The aluminum alloy AlMn1Cu has been broadly applied for functional parts production because of its good properties. But few researches about the machining mechanism and the surface roughness were reported. The high-speed milling experiments are carried out in order to improve the machining quality and reveal the machining mechanism. The typical topography features of machined surface are observed by scan electron microscope(SEM). The results show that the milled surface topography is mainly characterized by the plastic shearing deformation surface and material piling zone. The material flows plastically along the end cutting edge of the flat-end milling tool and meanwhile is extruded by the end cutting edge, resulting in that materials partly adhere to the machined surface and form the material piling zone. As the depth of cut and the feed per tooth increase, the plastic flow of materials is strengthened and the machined surface becomes rougher. However, as the cutting speed increases, the plastic flow of materials is weakened and the milled surface becomes smoother. The cutting parameters (e.g. cutting speed, feed per tooth and depth of cut) influencing the surface roughness are analyzed. It can be concluded that the roughness of the machined surface formed by the end cutting edge is less than that by the cylindrical cutting edge when a cylindrical flat-end mill tool is used for milling. The proposed research provides the typical topography features of machined surface of the anti-rust aluminum alloy AlMn1Cu in high speed milling. 相似文献
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Junfeng Xiang Siqin Pang Lijing Xie Xin Hu Song Peng Tao Wang 《The International Journal of Advanced Manufacturing Technology》2018,98(5-8):1237-1251
This paper focused on high-speed milling of Al6063 matrix composites reinforced with high-volume fraction of small-sized SiC particulates and provided systematic experimental study about cutting forces, thin-walled part deformation, surface integrity, and tool wear during high-speed end milling of 65% volume fraction SiCp/Al6063 (Al6063/SiCp/65p) composites in polycrystalline diamond (PCD) tooling. The machined surface morphologies reveal that the cutting mechanism of SiC particulates plays an important role in defect formation mechanisms on the machined surface. In high-speed end milling of Al6063/SiCp/65p composites, the cutting forces are influenced most considerably by axial depth of cut, and thus the axial depth of cut plays a dominant role in the thin-walled parts deformation. Increased milling speed within a certain range contributes to reducing surface roughness. The surface and sub-surface machined using high-speed milling suffered from less damage compared to low-speed milling. The milling speed influence on surface residual stress is associated with milling-induced heat and deformation. Micro-chipping, abrasive wear, graphitization, grain breaking off, and built-up edge are the dominated wear mechanism of PCD tools. Finally, a series of comparative experiments were performed to study the influence of tool nose radius, average diamond grain size, and machining parameters on PCD tool life. 相似文献
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基于最小二乘支持向量机的铣削加工表面粗糙度预测模型 总被引:3,自引:0,他引:3
在分析以往所建立的表面粗糙度预测模型方法不足的基础上,将一种基于最小二乘支持向量机的预测模型引入铣削加工领域,并给出了相应的步骤和算法。该模型能方便地预测铣削加工参数对加工表面粗糙度的影响,并能利用有限的试验数据得出整个工作范围内的表面粗糙度预测值,有助于准确认识已加工表面质量随铣削参数的变化规律。通过具体实例及与其他几种预测方法的对比表明,在相同样本条件下,其模型构造速度比标准支持向量机方法高1~2个数量级,模型预测误差约为支持向量机方法的40%,预测精度比常规BP模型高1个数量级。因此,基于最小二乘支持向量机方法建模速度快、预测精度高、适合加工表面粗糙度预测。 相似文献
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针对超声辅助加工在工件表面形成微刻划表面可以提高高强铝合金表面的微结构性能的现象,进行了单激励旋转超声纵扭复合铣削表面微观结构的试验,基于水接触角理论和纵扭铣削运动学理论分析了加工参数对水接触角的影响;搭建了单激励超声纵扭铣削试验平台,采用正交试验法研究了不同加工参数对表面粗糙度、铣削力以及表面润湿性能的影响。结果表明:超声振幅为4μm时表面质量最佳,切削速度和进给量与表面粗糙度和水接触角呈正相关的关系;超声加工方式下的表面水接触角较普通方式更大,而在超声加工时低振幅加工比高振幅加工的表面水接触角大,当转速达到一定值时,高振幅和低振幅所加工的表面水接触角差别不大。合适的加工参数条件下超声纵扭加工方式可以降低加工表面的粗糙度,改变表面的润湿性。 相似文献
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This article is concerned with the cutting forces and surface integrity in high-speed side milling of Ti-6Al-4V titanium alloy. The experiments were conducted with coated carbide cutting tools under dry cutting conditions. The effects of cutting parameters on the cutting forces, tool wear and surface integrity (including surface roughness, microhardness and microstructure beneath the machined surface) were investigated. The velocity effects are focused on in the present study. The experimental results show that the cutting forces in three directions increase with cutting speed, feed per tooth and depth of cut (DoC). The widths of flank wear VB increases rapidly with the increasing cutting speed. The surface roughness initially decreases and presents a minimum value at the cutting speed 200 m/min, and then increases with the cutting speed. The microstructure beneath the machined surfaces had minimal or no obvious plastic deformation under the present milling conditions. Work hardening leads to an increment in micro-hardness on the top surface. Furthermore, the hardness of machined surface decreases with the increase of cutting speed and feed per tooth due to thermal softening effects. The results indicated that the cutting speed 200 m/min could be considered as a critical value at which both relatively low cutting forces and improved surface quality can be obtained. 相似文献
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Cusp error reduction under high speed micro/meso- scale milling with ultrasonic vibration assistance
Jeong Hoon Ko Kah Chuan Shaw Han Kwang Chua Rong Ming Lin 《International Journal of Precision Engineering and Manufacturing》2011,12(1):15-20
In the conventional use of vibration assisted machining, vibratory motion is mostly applied to the continuous machining processes
such as turning where the cutting speed is much lower than the vibration speed. Even the recent articles on vibration assisted
milling processes are also quite limited to low spindle speed less than 3k RPM. This study investigates vibration assistance
that is applied to the workpiece in a high speed micro/meso-scale intermittent milling system where the cutting speed is much
higher than the vibration speed. In addition to this, the vibration effect is analyzed considering feed and cross-feed directional
application separately, which gives an idea of a right vibration assistance direction for surface quality improvement. To
validate this, a one-directional ultrasonic vibration assisted milling system with ultrasonic frequency at 40 kHz and with
amplitudes of a few microns is designed and its effect on the machined surface quality is investigated at high spindle RPMs
over 15k. As a result, cusp heights are found to be reduced with ultrasonic vibratory motion of cutting edge in high cutting
speed. Furthermore, the machined surface quality clearly tells that feed directional vibration assistance is able to generate
better surface quality with reduced wavy burrs than cross-feed directional vibration assistance. 相似文献
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Influence of cutting speed on surface integrity for powder metallurgy nickel-based superalloy FGH95 总被引:1,自引:1,他引:0
Du Jin Zhanqiang Liu Wan Yi Guosheng Su 《The International Journal of Advanced Manufacturing Technology》2011,56(5-8):553-559
Powder metallurgy (PM) nickel-based superalloy FGH95 has been widely used for components, which requires the greatest service performance. The surface integrity is becoming more and more important in order to satisfy the increasing service demands. However, the machined surface of FGH95 is easily damaged due to its poor machinability. The purpose of this paper is to investigate the effects of dry milling process parameters on the surface integrity of FGH95. Experiments were conducted on a CNC machining center under different cutting speeds. The machined surface is evaluated in terms of surface roughness, microhardness and white layer. Experiments results show milled surface integrity of FGH95 is sensitivity to the cutting speeds. The machined surface roughness decreases with increase of the cutting speed, but with further increase of cutting speed between 80?m/min to 100?m/min an increase in surface roughness appears. For microhardness, it can be seen that the machined workpiece surface hardens seriously. It can also draw the conclusion that cutting speed has the marginal effect on the white layer thickness generated in the machined subsurface. 相似文献
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The work refers to analysis of various factors affecting surface roughness after end milling of hardened steel in high-speed milling (HSM) conditions. Investigations of milling parameters (cutting speed v(c) , axial depth of cut a(p) ) and the process dynamics that influence machined surface roughness were presented, and a surface roughness model, including cutter displacements, was elaborated. The work also involved analysis of surface profile charts from the point of view of vibrations and cutting force components. The research showed that theoretic surface roughness resulting from the kinematic-geometric projection of cutting edge in the workpiece is significantly different from the reality. The dominant factor in the research was not feed per tooth f(z) (according to the theoretical model) but dynamical phenomena and feed per revolution f. 相似文献
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Lin Yang Shi Wu Xianli Liu Zhijing Liu Meiwen Zhu Zhonghua Li 《The International Journal of Advanced Manufacturing Technology》2018,98(1-4):151-163
In the milling process of automobile panel mold of hardened steel, the characteristic of free-form surface is one of the dominant factors for surface topography. In this paper, the trajectory of cutting edge is firstly modeled to analyze the residual height of the free-form surface in ball-end milling of hardened steel. Furthermore, the non-uniform rational B-splines (NURBS) surface reconstruction is utilized to generate the surface topography. Subsequently, the influences of surface curvature, lead angle, milling vibrations on the machined surface topography, and residual height are investigated, respectively. Finally, the accuracy of the surface topography and the roughness prediction model are validated by the milling experiments of free-form surface, where two-dimensional contour maps could be obtained. The simulation and experimental results demonstrate that the machined surface topography of hardened steel is fitted by means of NURBS surface reconstruction. In that manner, the effects of surface characteristics on the machined surface topography can be accurately predicted. 相似文献
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数控铣削加工中常常会遇到一些复杂轮廓棱边倒圆角的加工。针对使用软件自动编程的加工方法的缺陷问题,建立了倒圆角数学模型,讨论了复杂轮廓的宏程序实现及变半径补偿的编程方法,提出了一类复杂轮廓的倒圆角的加工程序编制方法,并举例说明了编程方法。该倒圆角方法可提高产品的加工效率和产品圆角表面质量。 相似文献