International Journal of Machine Tools & Manufacture最新文献

Combining in situ synchrotron X-ray imaging and multiphysics simulation to reveal pore formation dynamics in laser welding of copper 结合原位同步辐射 X 射线成像和多物理场模拟揭示铜激光焊接中的孔隙形成动力学

IF 14 1区工程技术 Q1 ENGINEERING, MANUFACTURING

International Journal of Machine Tools & Manufacture

Pub Date : 2024-10-28 DOI: 10.1016/j.ijmachtools.2024.104224

T. Florian , K. Schricker , C. Zenz , A. Otto , L. Schmidt , C. Diegel , H. Friedmann , M. Seibold , P. Hellwig , F. Fröhlich , F. Nagel , P. Kallage , M. Buttazzoni , A. Rack , H. Requardt , Y. Chen , J.P. Bergmann

Laser beam welding has emerged as a powerful tool for manufacturing copper components in electrical vehicles, electronic devices or energy storage, owing to its rapid processing capabilities. Nonetheless, the material’s high thermal conductivity and low absorption of infrared light can introduce process instabilities, resulting in defects such as pores. This study employs a hybrid approach that combines in situ synchrotron X-ray imaging with compressible multiphysics process simulation to elucidate pore-forming mechanisms during laser beam welding of copper. High-speed synchrotron X-ray imaging with an acquisition rate of 20,000 images/second facilitates the identification of relevant process regimes concerning pore formation during laser beam welding of copper with a wavelength of 1070 nm. Furthermore, in situ observations with high temporal and spatial resolution present a unique database for extensive validation of a multi-physics process simulation based on welding processes using different concentric intensity distributions. These validated simulation results enable thorough comprehension of process-related pore formation based on the interaction between keyhole, melt pool and resulting flow field. The findings show that pore formation is driven by four different mechanisms: bulging, spiking, upwelling waves at the keyhole rear wall and melt pool ejections. The synergy of high-speed synchrotron X-ray imaging and multi-physics modeling provides a fundamental understanding of the chronological sequence of events leading to process-related pore formation during laser beam welding of copper.

激光束焊接因其快速的加工能力，已成为制造电动汽车、电子设备或能源储存领域铜部件的有力工具。然而，铜材料的高热导率和对红外光的低吸收率会导致加工过程不稳定，从而产生气孔等缺陷。本研究采用了一种混合方法，将原位同步辐射 X 射线成像与可压缩多物理场过程模拟相结合，以阐明铜激光束焊接过程中的孔隙形成机制。以每秒 20,000 张图像的采集速度进行的高速同步辐射 X 射线成像有助于确定波长为 1070 纳米的铜激光焊接过程中孔隙形成的相关过程机制。此外，具有高时间和空间分辨率的现场观测还提供了一个独特的数据库，用于广泛验证基于使用不同同心强度分布的焊接过程的多物理过程模拟。这些经过验证的模拟结果使我们能够根据钥匙孔、熔池和由此产生的流场之间的相互作用，透彻地理解与工艺相关的孔隙形成。研究结果表明，孔隙的形成是由四种不同的机制驱动的：隆起、尖峰、键孔后壁的上涌波和熔池喷射。通过高速同步辐射 X 射线成像和多物理场建模的协同作用，可以从根本上了解铜激光束焊接过程中与工艺相关的孔隙形成事件的时间顺序。

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引用次数: 0

A distinctive material removal mechanism in the diamond grinding of (0001)-oriented single crystal gallium nitride and its implications in substrate manufacturing of brittle materials 金刚石磨削（0001）取向单晶氮化镓时的独特材料去除机制及其对脆性材料基底制造的影响

IF 14 1区工程技术 Q1 ENGINEERING, MANUFACTURING

International Journal of Machine Tools & Manufacture

Pub Date : 2024-10-23 DOI: 10.1016/j.ijmachtools.2024.104222

Yueqin Wu , Qijian Rao , Zhiyuan Qin , Shuiping Tan , Guoqin Huang , Hui Huang , Xipeng Xu , Han Huang

Single crystal gallium nitride (GaN) substrates are highly demanded for fabricating advanced optoelectronic devices. It is thus essential to develop high efficiency machining technologies for this difficult-to-machine material, which in turn necessitates a thorough understanding of its deformation mechanism. In this study, the deformation and removal characteristics of (0001)-oriented single crystal GaN involved in diamond grinding were systematically investigated. The material removal exhibited a brittle mode when using relatively coarse diamond abrasives of 2000 in mesh size, while ductile removal was achieved when diamond abrasives of 6000 in mesh size were utilized. A novel peeling phenomenon was observed along (0001) lattice plane (c-plane) in the coarse grinding, as the crystal has a hexagonal crystal structure with c-planes serving as the preferable slip/cracking planes. Peeling observed in material removal agrees well with the findings that lateral planar defects were prone to initiate in nanoscratching in comparison to nanoindentation in the ductile regime, indicating that the effect of tangential grinding force is significant. The application of Molecular dynamics (MD) simulations, employing smaller indentation/scratching models, provided additional confirmation of the crucial role played by lateral force in initiating planar defects on c-planes. Furthermore, larger-scale MD scratching models substantiated the occurrence of peeling in the deformation process on c-plane, a finding corroborated by scratching experiments conducted in the brittle regime. Conversely, such peeling is absent on m- and a-planes. Complementary to the simulations, specifically designed grinding experiments were conducted to empirically demonstrate that peeling phenomena were intensified with elevated rotational wheel speeds. This enhancement was attributed to the increased tangential grinding force associated with higher speeds. These findings contribute to a comprehensive understanding of the intricate relationship between rotational wheel speed, tangential grinding force, and the observed peeling mechanisms in the context of single crystal GaN machining.

制造先进光电设备对单晶氮化镓（GaN）衬底的需求量很大。因此，开发针对这种难加工材料的高效加工技术至关重要，这反过来又要求对其变形机理有透彻的了解。在本研究中，系统地研究了金刚石磨削过程中(0001)取向单晶氮化镓的变形和去除特性。当使用目数为 2000 的相对较粗的金刚石磨料时，材料去除呈现出脆性模式，而当使用目数为 6000 的金刚石磨料时，则实现了韧性去除。在粗磨过程中，沿（0001）晶格面（c-平面）观察到了一种新的剥离现象，因为该晶体具有六方晶系结构，c-平面是理想的滑移/开裂平面。在材料去除过程中观察到的剥离现象与韧性机制中的纳米压痕相比，横向平面缺陷更容易在纳米划痕中产生的发现完全一致，表明切向磨削力的影响是显著的。采用较小的压痕/划痕模型进行分子动力学（MD）模拟，进一步证实了横向力在引发 c 平面上的平面缺陷方面所起的关键作用。此外，更大尺度的 MD 划痕模型证实了在 c 平面的变形过程中出现了剥离现象，在脆性体系中进行的划痕实验也证实了这一发现。相反，在 m 平面和 a 平面上则不存在这种剥离现象。作为对模拟的补充，还进行了专门设计的磨削实验，以经验证明剥离现象随着砂轮转速的提高而加剧。这种现象的加剧归因于与更高转速相关的切向磨削力的增加。这些发现有助于全面了解砂轮转速、切向磨削力和单晶氮化镓加工中观察到的剥离机制之间的复杂关系。

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引用次数: 0

Strengthening flat-die friction self-pierce riveting joints via manipulating stir zone geometry by tailored rivet structures 通过量身定制的铆钉结构操纵搅拌区的几何形状来强化平模摩擦自冲铆接接头

IF 14 1区工程技术 Q1 ENGINEERING, MANUFACTURING

International Journal of Machine Tools & Manufacture

Pub Date : 2024-10-19 DOI: 10.1016/j.ijmachtools.2024.104223

Bowen Zhang , Yunwu Ma , Feilong Yu , Yunpeng Liu , Entao Zhou , Zhilei Fan , Ende Ge , Yongbing Li , Zhongqin Lin

Achieving high-strength joints with flat surfaces is of significant importance for reducing wind resistance and enhancing aesthetic appeal. In this study, a novel flat-die friction self-piercing riveting (flat-die F-SPR) process is proposed. The rivet flaring without die guidance was achieved through the sophisticated design of rivet structures. Three types of rivets with different internal structures were designed to manipulate the material flow and microstructure evolution during the joining process. Based on the method of emergency stop, the load-stroke curves, evolutions of macroscopic morphology, and microstructure of the joints made with different rivets were investigated. A novel mechanism for solid-state bonding of joints was proposed to elucidate the generation and evolution of fine grain regions. The results indicate when downward pressure is applied to the material inside the rivet cavity, a central stirring zone appears. By using a rivet with an annular boss structure, the base material flows continuously into the stirring zone and piled up in the rivet cavity, forming a unique conical-shaped fine grain zone. Finally, a comprehensive assessment of the strength of different types of joints and the transition of the fracture modes were conducted based on different lower sheet thicknesses. The joints of Rivet_B and Rivet_C demonstrate 11.1 % and 6.9 % strength enhancement compared with the joint of Rivet_A, respectively. Two strategies for enhancing the strength of solid-state bonding are proposed, which offers insights for the optimizations of rivet structures.

实现表面平整的高强度接缝对于降低风阻和提高美观度具有重要意义。本研究提出了一种新型平模摩擦自冲铆接（平模 F-SPR）工艺。通过对铆钉结构的精密设计，实现了无模具导向的铆钉翻边。设计了三种具有不同内部结构的铆钉，以控制连接过程中的材料流动和微观结构演变。基于急停方法，研究了使用不同铆钉制造的接头的载荷-行程曲线、宏观形态和微观结构的演变。提出了接头固态粘接的新机制，以阐明细晶粒区域的生成和演变。结果表明，当铆钉腔内的材料受到向下的压力时，会出现一个中心搅拌区。通过使用环形凸台结构的铆钉，基体材料不断流入搅拌区并在铆钉腔内堆积，形成了独特的锥形细晶粒区。最后，根据不同的下片厚度，对不同类型接头的强度和断裂模式的转变进行了综合评估。与 Rivet_A 的接头相比，Rivet_B 和 Rivet_C 的接头强度分别提高了 11.1% 和 6.9%。本文提出了提高固态粘接强度的两种策略，为铆钉结构的优化提供了启示。

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引用次数: 0

A novel method of induction electrode through-mask electrochemical micromachining 感应电极通罩电化学微加工新方法

IF 14 1区工程技术 Q1 ENGINEERING, MANUFACTURING

International Journal of Machine Tools & Manufacture

Pub Date : 2024-10-13 DOI: 10.1016/j.ijmachtools.2024.104221

Xiaochen Yang , Liqun Du , Aoqi Li , Mengxi Wu , Changhao Wu , Jingmin Li

Through-mask electrochemical micromachining (TMEMM) is a key method for fabricating metal microstructures. However, the accuracy of TMEMM often falls short of the stringent requirements for many applications, primarily due to the uncontrolled electric field during the machining process. To overcome this limitation, this paper introduces a novel method: induction electrode through-mask electrochemical micromachining (IETMEMM). In this method, two feeder electrodes act as the anode and cathode, generating an electric field where the wireless workpiece is placed. This study explores the principles of electric field control in IETMEMM and develops a simulation model to highlight the method's unique advantages under specific electric field distributions. The findings indicate substantial improvements. Leveraging the self-stopping feature, a MEMS inertial switch was fabricated with high accuracy, achieving a non-uniformity of just 3.8%—a remarkable 96.2 % enhancement in accuracy compared to traditional TMEMM. Additionally, the gradient etching advantage facilitated the creation of both gradient-depth and V-shaped microchannel arrays. Moreover, the parallel machining advantage enabled the simultaneous fabrication of three identical microstructures in just 20 s. These outcomes demonstrate the significant potential of IETMEMM for industrial applications.

掩膜电化学微机械加工（TMEMM）是制造金属微结构的一种关键方法。然而，TMEMM 的精度往往达不到许多应用的严格要求，这主要是由于加工过程中电场不受控制。为了克服这一限制，本文介绍了一种新方法：感应电极通过掩模电化学微加工（IETMEMM）。在这种方法中，两个馈电电极充当阳极和阴极，在放置无线工件的地方产生电场。本研究探讨了 IETMEMM 的电场控制原理，并开发了一个仿真模型，以突出该方法在特定电场分布下的独特优势。研究结果表明，该方法有很大改进。利用自停止功能，制造出了高精度的 MEMS 惯性开关，非均匀性仅为 3.8%，与传统的 TMEMM 相比，精度显著提高了 96.2%。此外，梯度蚀刻的优势还有助于创建梯度深度和 V 形微通道阵列。这些成果证明了 IETMEMM 在工业应用方面的巨大潜力。

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引用次数: 0

Investigation on the material removal mechanism in ion implantation-assisted elliptical vibration cutting of hard and brittle material 离子注入辅助椭圆振动切割硬脆材料的材料去除机理研究

IF 14 1区工程技术 Q1 ENGINEERING, MANUFACTURING

International Journal of Machine Tools & Manufacture

Pub Date : 2024-10-03 DOI: 10.1016/j.ijmachtools.2024.104220

Jinyang Ke , Jianguo Zhang , Xiao Chen , Changlin Liu , Gui Long , Hao Sun , Jianfeng Xu

Ductile-regime machining has been used to generate damage-free surface of hard and brittle materials by setting the cutting depth to be smaller than the ductile-brittle transition depth (DBTD). However, the ductile-regime cutting of sapphire remains challenging owing to its extreme hardness, small DBTD, serious surface fractures, and severe tool wear. To solve this problem, ion implantation-assisted elliptical vibration cutting (Ii-EVC) has been proposed in this study to enhance the machinability of hard and brittle materials. Taking sapphire as an example, high-energy phosphorus ions were implanted into the workpiece to modify its surface. Nanoindentation tests revealed that the modified materials undergo plastic and elastic deformation more easily due to the decrease in hardness and modulus. Compared with nanocutting without implantation assistance, the DBTD of implanted sapphire has been increased by more than five times. The advantageous effects of Ii-EVC achieve great enhancement in machinability, including surface fractures suppression, tool-wear reduction, chips morphology transformation from discontinuous to continuous, and cutting force decrease. Furthermore, even near the cracks in the brittle region after Ii-EVC, the subsurface microstructure showed a more complete lattice arrangement and a strain distribution close to zero, indicating that crack propagation was effectively suppressed. Due to the promoted localized plastic deformation, the stress distribution in the implanted material is much smaller than that in pristine workpiece. Implantation-induced defects not only serve as a core for absorbing external energy from the high-frequency vibration and improving the in-grain deformation but also facilitate the formation of shear bands. The interface with high distortion between the modified layer and substrate can effectively dissipate strain energy and hinder crack propagation to the free surface. The turning experiments verified that Ii-EVC can achieve better surface quality, less tool wear and higher optical transmittance. Overall, Ii-EVC addresses the challenges of tool breakage and surface fracture caused by high-frequency collision between tool and workpiece in traditional EVC, overcomes the problem of limited modification depth in ion implantation, and increases the ductile-regime removal depth of extremely hard and brittle materials to several microns. Such findings demonstrate that Ii-EVC is a promising method for the ultra-precision manufacturing of advanced materials.

通过将切削深度设定为小于韧性-脆性过渡深度（DBTD），韧性-韧性加工已被用于加工硬脆材料的无损表面。然而，由于蓝宝石的硬度极高、DBTD 较小、表面断裂严重以及刀具磨损严重，蓝宝石的韧性-韧性切削仍然具有挑战性。为解决这一问题，本研究提出了离子注入辅助椭圆振动切割（Ii-EVC）技术，以提高硬脆材料的加工性能。以蓝宝石为例，将高能磷离子植入工件以改变其表面。纳米压痕测试表明，由于硬度和模量的降低，改性材料更容易发生塑性和弹性变形。与没有植入辅助的纳米切割相比，植入蓝宝石的 DBTD 增加了五倍以上。Ii-EVC 的优势效应大大提高了加工性能，包括抑制表面断裂、减少刀具磨损、切屑形态从不连续性转变为连续性以及降低切削力。此外，即使在 Ii-EVC 后脆性区域的裂纹附近，表层下的微观结构也显示出更完整的晶格排列和接近零的应变分布，表明裂纹扩展得到了有效抑制。由于促进了局部塑性变形，植入材料的应力分布远小于原始工件。植入引起的缺陷不仅可以作为吸收高频振动外部能量和改善晶粒内部变形的核心，还能促进剪切带的形成。改性层与基体之间的高畸变界面可有效耗散应变能，阻碍裂纹向自由表面扩展。车削实验验证了 Ii-EVC 可以获得更好的表面质量、更少的刀具磨损和更高的光学透射率。总之，Ii-EVC 解决了传统 EVC 中刀具与工件高频碰撞导致的刀具破损和表面断裂难题，克服了离子注入中改性深度有限的问题，并将极硬极脆材料的韧性--定常去除深度提高到几微米。这些研究结果表明，Ii-EVC 是一种很有前途的先进材料超精密制造方法。

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引用次数: 0

Cutting mechanism of reaction-bonded silicon carbide in laser-assisted ultra-precision machining 激光辅助超精密加工中反应结合碳化硅的切削机理

IF 14 1区工程技术 Q1 ENGINEERING, MANUFACTURING

International Journal of Machine Tools & Manufacture

Pub Date : 2024-10-02 DOI: 10.1016/j.ijmachtools.2024.104219

Changlin Liu , Jinyang Ke , Tengfei Yin , Wai Sze Yip , Jianguo Zhang , Suet To , Jianfeng Xu

Reaction-bonded silicon carbide (RB-SiC) is an important material used in aerospace optical systems. Due to the property mismatch between Si and SiC phases, the underlying cutting mechanism in ultra-precision machining of RB-SiC remains relatively unclear. Recently, laser-assisted machining (LAM) has emerged as an effective technique to improve the machinability of hard and brittle materials, which brings the question that how the high temperature affects the machining mechanism of RB-SiC. To elucidate these aspects, a series of grooving experiments and MD simulations were conducted in this study. The interaction mechanism between phases on material removal and subsurface damage was revealed and the effect of cutting temperature on Si-SiC interaction was explored. The results indicate that in conventional ultra-precision machining, SiC grains could affect the deformation of Si phase, whereas the influence of Si phase on SiC deformation is limited. As the cutting temperature increases, the Si-SiC interaction is less apparent and the deformation of Si and SiC becomes more independent. Meanwhile, the prominence of phase property mismatch on subsurface damage are reduced while the extension of disordered phases into boundaries merges as an important mechanism in subsurface damage formation. This research helps to understand the thermal effect on material interaction between phases during machining and aid to improve the performance of LAM on RB-SiC.

反应结合碳化硅（RB-SiC）是航空航天光学系统中使用的一种重要材料。由于 Si 相和 SiC 相之间的性质不匹配，RB-SiC 超精密加工的基本切削机制仍相对不清楚。最近，激光辅助加工（LAM）已成为提高硬脆材料可加工性的有效技术，这就带来了高温如何影响 RB-SiC 加工机制的问题。为了阐明这些问题，本研究进行了一系列开槽实验和 MD 模拟。研究揭示了材料去除和表面下损伤相之间的相互作用机理，并探讨了切削温度对 Si-SiC 相互作用的影响。结果表明，在传统超精密加工中，SiC 晶粒会影响 Si 相的变形，而 Si 相对 SiC 变形的影响有限。随着切削温度的升高，Si-SiC 的相互作用变得不那么明显，Si 和 SiC 的变形变得更加独立。同时，相性质不匹配对次表面损伤的影响减小，而无序相向边界的扩展合并成为次表面损伤形成的重要机制。这项研究有助于理解加工过程中热对材料相间相互作用的影响，并有助于改善 RB-SiC 的 LAM 性能。

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引用次数: 0

Leveraging artificial intelligence for real-time indirect tool condition monitoring: From theoretical and technological progress to industrial applications 利用人工智能进行实时间接工具状态监测：从理论和技术进步到工业应用

IF 14 1区工程技术 Q1 ENGINEERING, MANUFACTURING

International Journal of Machine Tools & Manufacture

Pub Date : 2024-09-12 DOI: 10.1016/j.ijmachtools.2024.104209

Delin Liu , Zhanqiang Liu , Bing Wang , Qinghua Song , Hongxin Wang , Lizeng Zhang

Tool condition monitoring (TCM) during mechanical cutting is critical for maximising the utilisation of cutting tools and minimising the risk of equipment damage and personnel injury. The demand for highly efficient and sustainable machining in modern industries has led to the development of new processes operating under specific conditions. Real-world datasets obtained under harsh cutting conditions often suffer from intense interference, making the anti-interference capabilities of TCM methods crucial for effective industrial applications. Previous literature reviews on TCM have focused on theoretical methods for monitoring tool wear and breakage. However, reviews of the scientific methodologies and technologies employed in TCM for industrial production are limited. The lack of scientific understanding relevant to the monitoring of cutting tools in industrial production should be addressed urgently. The current data processing, feature dimensionality reduction, and decision-making methods utilised in TCM may not adequately fulfil the real-time and anti-interference demands. The TCM methods also face the challenges of small sample sizes and imbalanced data during real-world dataset processing. Therefore, this study conducts a systematic review of TCM methods to overcome these limitations. First, the theoretical guidelines for the application of TCM methods in industrial production are provided. The sensing system, signal processing, feature dimensionality reduction, and decision-making methods for TCM methods are comprehensively discussed in terms of both their advantages and limitations for applications in industrial production. Considering the effects of real-world datasets with small samples and imbalanced data caused by the harsh environment of a real factory, a systematic presentation is proposed at the data, feature, and decision levels. Finally, the challenges and potential research directions of TCM methods for industrial applications are discussed. A research route for smart factory-oriented machining system management is proposed based on published literature. This review bridges the gap between theoretical research and the industrial application of TCM techniques in industrial production. Prospective research and further development of TCM systems will provide the groundwork for establishing smart factories.

机械切削过程中的刀具状态监测（TCM）对于最大限度地利用切削刀具、降低设备损坏和人员伤害风险至关重要。现代工业对高效和可持续加工的需求促使人们开发出在特定条件下运行的新工艺。在苛刻的切削条件下获得的真实数据集通常会受到强烈干扰，因此 TCM 方法的抗干扰能力对于有效的工业应用至关重要。以往有关 TCM 的文献综述主要集中在监测刀具磨损和破损的理论方法上。然而，有关工业生产中使用的 TCM 科学方法和技术的综述却十分有限。对工业生产中切削工具监测缺乏科学认识的问题亟待解决。目前中医药中使用的数据处理、特征降维和决策方法可能无法充分满足实时性和抗干扰性的要求。在现实世界的数据集处理过程中，中医方法还面临样本量小和数据不平衡的挑战。因此，本研究对中医方法进行了系统回顾，以克服这些局限性。首先，为 TCM 方法在工业生产中的应用提供了理论指导。全面讨论了 TCM 方法的传感系统、信号处理、特征降维和决策方法在工业生产中应用的优势和局限性。考虑到小样本真实数据集和真实工厂恶劣环境造成的不平衡数据的影响，从数据、特征和决策三个层面提出了系统的介绍。最后，讨论了 TCM 方法在工业应用中面临的挑战和潜在的研究方向。根据已发表的文献，提出了面向工厂的智能加工系统管理的研究路线。这篇综述弥补了理论研究与 TCM 技术在工业生产中的工业应用之间的差距。中医药系统的前瞻性研究和进一步发展将为建立智能工厂奠定基础。

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引用次数: 0

Optimal milling cutter helix selection for period doubling chatter suppression 优化铣刀螺旋选择，抑制周期加倍颤振

IF 14 1区工程技术 Q1 ENGINEERING, MANUFACTURING

International Journal of Machine Tools & Manufacture

Pub Date : 2024-09-10 DOI: 10.1016/j.ijmachtools.2024.104211

M. Sanz-Calle , A. Iglesias , L.N. López de Lacalle , Z. Dombovari , J. Munoa

In high speed milling, interrupted cutting conditions can lead to period doubling chatter vibrations. While many studies have already confirmed that the use of helical tools can effectively shrink or remove these regions of unstable cutting, none of them has provided clear guidance to select the minimum helix that completely cancels the period doubling lobes. This study addresses this gap by introducing a novel analytical formula for a critical tool helix pitch: if the helix pitch is below the critical flip depth of cut of the straight helix cutter multiplied by $π$ , the flip lobes will totally vanish. This rule is not only valuable for chatter-free process planning purposes, but it also establishes exact limit below which the fast and simple zeroth order stability algorithm can provide exact stability boundaries for helical tools. The effectiveness of the formula is numerically corroborated over three different milling scenarios: thin wall milling, slender tool and machine tool structure chatter cases. Finally, the findings are validated through experimental cutting tests.

在高速铣削中，断续切削条件会导致周期倍频颤振。虽然许多研究已经证实，使用螺旋刀具可以有效地缩小或消除这些不稳定的切削区域，但没有一项研究为选择能完全消除周期倍频振叶的最小螺旋度提供了明确的指导。本研究针对这一缺陷，提出了一个新颖的临界刀具螺旋间距分析公式：如果螺旋间距低于直螺旋刀具的临界翻转切削深度乘以 π，翻转裂片将完全消失。该规则不仅对无颤振工艺规划很有价值，而且还建立了精确的极限，在该极限以下，快速简单的零阶稳定性算法可以为螺旋刀具提供精确的稳定性边界。该公式的有效性通过三种不同的铣削情况进行了数值验证：薄壁铣削、细长刀具和机床结构颤振情况。最后，通过切削实验验证了上述结论。

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引用次数: 0

Achieving fine tailoring of elastocaloric properties of laser powder bed-fused NiTi alloy via laser beam manipulation 通过激光束操纵实现激光粉末床熔融镍钛合金弹性特性的微调

IF 14 1区工程技术 Q1 ENGINEERING, MANUFACTURING

International Journal of Machine Tools & Manufacture

Pub Date : 2024-09-10 DOI: 10.1016/j.ijmachtools.2024.104210

Jianbin Zhan , Kun Li , Ruijin Ma , Liang Zhu , Jiahui Fang , Huajun Cao , David Z. Zhang , Lawrence E. Murr

Laser powder bed fusion (LPBF) technology enables the development of NiTi alloys with complex geometries and tunable phase-transformation temperatures (PTTs). This technology is increasingly acknowledged as promising in the field of elastocaloric (eC) refrigeration. However, the mechanisms governing the manner in which this technology tunes the eC performance remain ambiguous. This study evaluated the fine-tuning of the eC properties by regulating Ni evaporation through laser manipulation. Our results demonstrate that although adjusting Ni loss via laser heat input can effectively control the PTTs, inappropriate combinations of laser parameters may result in lower than anticipated cooling capacity (ΔT_ad) and coefficient of performance (COP_mat) of produced samples. An excessive heat input results in Ni evaporation and in grain coarsening through the remelting and combination of fine grains owing to overlapping molten pools. Lower Ni enhances the phase-transformation enthalpy (ΔH_tr). However, larger grains increase the energy dissipation and thereby, counteracting ΔT_ad improvements. Theoretical analysis and experiments revealed that finer grains increase the misorientation angles. This hinders the dislocation motion and thereby, enhances the mechanical properties. Meanwhile, coarser grains can more conveniently promote PT and thereby, increase ΔH_tr. Thus, based on the naturally controllable grain size heterogeneity in LPBF-manufactured NiTi alloys, we propose optimizing the eC properties by controlling the morphology of the molten pool. Thermal-history simulations could balance this relationship. Ultimately, we developed two NiTi alloys for both high-temperature (70 °C) and room-temperature (25 °C) refrigeration. This study has provided effective insights for customizing high-performance eC components such as multistage caloric cascade regenerators, using additive manufacturing.

激光粉末床熔融（LPBF）技术能够开发出具有复杂几何形状和可调相变温度（PTT）的镍钛合金。这项技术在弹性制冷（eC）领域的前景日益广阔。然而，该技术调整 eC 性能的机制仍不明确。本研究评估了通过激光操作调节镍蒸发来微调 eC 性能的情况。我们的结果表明，虽然通过激光热输入调节镍损耗可以有效控制 PTT，但激光参数组合不当可能会导致生产的样品冷却能力（）和性能系数（）低于预期。过多的热量输入会导致镍蒸发，并由于熔池重叠导致细小晶粒的重熔和组合而使晶粒变粗。镍含量越低，相变焓（）越高。然而，较大的晶粒会增加能量耗散，从而抵消改善作用。理论分析和实验表明，晶粒越细，错向角越大。这阻碍了位错运动，从而提高了机械性能。同时，较粗的晶粒可以更方便地促进位错运动，从而提高机械性能。因此，基于 LPBF 制造的镍钛合金中自然可控的晶粒尺寸异质性，我们建议通过控制熔池的形态来优化 eC 性能。热历史模拟可以平衡这种关系。最终，我们开发出了两种适用于高温（70 °C）和室温（25 °C）制冷的镍钛合金。这项研究为利用增材制造技术定制高性能 eC 组件（如多级热量级联再生器）提供了有效的启示。

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引用次数: 0

Magnetic and ultrasonic vibration dual-field assisted ultra-precision diamond cutting of high-entropy alloys 磁场和超声波振动双场辅助超精密金刚石切割高熵合金

IF 14 1区工程技术 Q1 ENGINEERING, MANUFACTURING

International Journal of Machine Tools & Manufacture

Pub Date : 2024-09-03 DOI: 10.1016/j.ijmachtools.2024.104208

Yintian Xing , Yue Liu , Tengfei Yin , Denghui Li , Zhanwen Sun , Changxi Xue , Wai Sze Yip , Suet To

Despite the remarkable achievements in single-energy field-assisted diamond cutting technology, its performance remains unsatisfactory for processing high-entropy alloys (HEAs), targeted for next-generation large-scale industrial applications due to their exceptional properties. The challenge lies in overcoming the limitations of current single-energy field-assisted processing to achieve ultra-precision manufacturing of these advanced materials. This study proposes a multi-energy field-assisted ultra-precision machining technology, the magnetic and ultrasonic vibration dual-field assisted diamond cutting (MUVFDC), to address the current challenges. The phenomenological aspects of the dual-field coupling effect on HEAs are explored and investigated through comprehensive characterization of the workpiece material, ranging from macroscopic surface morphology to microscopic structural features. These analyses are performed based on experimental results from four different processing technologies: non-energy field, magnetic field, ultrasonic vibration field, and dual-field assisted machining. Research results demonstrate that MUVFDC technology effectively combines the advantages of a vibration field, which enhances cutting stability, and a magnetic field, which improves the machinability of materials. Additionally, this coupling technology addresses the challenges associated with single-energy field machining: it mitigates the difficulty of controlling surface scratches caused by tiny hard particles in a vibration field and suppresses the rapid tool wear encountered in a magnetic field. Furthermore, the gradient evolution of the subsurface microstructure reveals that the vibration field suppresses the severe matrix deformation induced by magnetic excitation. Simultaneously, the magnetic field reduces the size inhomogeneity of recrystallized grains caused by intermittent cutting. Overall, MUVFDC technology enhances surface quality, suppresses tool wear, smooths chip morphology, and reduces subsurface damage compared to single-energy field or non-energy-assisted machining. This work breaks through the performance limitations of traditional single-energy field-assisted processing and advances the understanding of the dual-field coupling effects in HEAs machining. It also presents a promising processing technology for the future ultra-precision manufacturing of advanced materials.

尽管单能场辅助金刚石切割技术取得了令人瞩目的成就，但在加工高熵合金（HEAs）时，其性能仍不尽如人意。如何克服当前单能量场辅助加工的局限性，实现这些先进材料的超精密制造，是一项挑战。本研究提出了一种多能量场辅助超精密加工技术--磁场和超声波振动双场辅助金刚石切割（MUVFDC），以应对当前的挑战。通过对工件材料从宏观表面形态到微观结构特征的全面表征，探索和研究了双场耦合效应对 HEA 的现象学影响。这些分析基于四种不同加工技术的实验结果：非能量场、磁场、超声振动场和双场辅助加工。研究结果表明，MUVFDC 技术有效地结合了振动场和磁场的优势，前者可提高切削稳定性，后者可改善材料的可加工性。此外，这种耦合技术还解决了与单能场加工相关的难题：它减轻了控制振动场中微小硬质颗粒造成的表面划痕的难度，并抑制了磁场中刀具的快速磨损。此外，表面下微观结构的梯度演变表明，振动场抑制了磁激励引起的严重基体变形。同时，磁场减少了间歇切削造成的再结晶晶粒尺寸不均匀性。总体而言，与单能量场或非能量辅助加工相比，MUVFDC 技术可提高表面质量、抑制刀具磨损、平滑切屑形态并减少表面下损伤。这项工作突破了传统单能量场辅助加工的性能限制，加深了人们对 HEAs 加工中双场耦合效应的理解。它还为未来先进材料的超精密制造提供了一种前景广阔的加工技术。

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引用次数: 0