Search | Engineering

订阅投稿

首页工程期刊工程焦点工程成就工程前沿关于我们 English

资源类型

期刊论文 23

会议视频 1

年份

2023 2

2022 3

2021 4

2020 1

2019 1

2018 4

2017 4

2016 2

2009 1

2007 1

2000 1

展开︾

关键词

气体辅助注射成型 2

兆瓦级电力电子 1

光刻 1

加强筋 1

单壳体结构 1

可切换移相器 1

可重构超表面 1

天线 1

对跖Vivaldi天线；超宽带；高介电常数；双极化；超表面透镜 1

广义混杂系统 1

建模仿真 1

建筑 1

成像 1

扩展半球介质透镜 1

扫描阵列 1

数值凸透镜 1

智能制造 1

柔性成型系统 1

桥梁设计 1

展开︾

检索范围：

排序：展示方式：

Review of small aspheric glass lens molding technologies

Shaohui YIN,Hongpeng JIA,Guanhua ZHANG,Fengjun CHEN,Kejun ZHU

《机械工程前沿（英文）》 2017年第12卷第1期页码 66-76 doi: 10.1007/s11465-017-0417-2

摘要：

Aspheric lens can eliminate spherical aberrations, coma, astigmatism, field distortions, and other adverse factors. This type of lens can also reduce the loss of light energy and obtain high-quality images and optical characteristics. The demand for aspheric lens has increased in recent years because of its advantageous use in the electronics industry, particularly for compact, portable devices and high-performance products. As an advanced manufacturing technology, the glass lens molding process has been recognized as a low-cost and high-efficiency manufacturing technology for machining small-diameter aspheric lens for industrial production. However, the residual stress and profile deviation of the glass lens are greatly affected by various key technologies for glass lens molding, including glass and mold-die material forming, mold-die machining, and lens molding. These key technical factors, which affect the quality of the glass lens molding process, are systematically discussed and reviewed to solve the existing technical bottlenecks and problems, as well as to predict the potential applicability of glass lens molding in the future.

关键词： aspheric glass lens mold-die manufacturing lens molding molding process simulation

HTML PDF 收藏

Precision glass molding: Toward an optimal fabrication of optical lenses

Liangchi ZHANG,Weidong LIU

《机械工程前沿（英文）》 2017年第12卷第1期页码 3-17 doi: 10.1007/s11465-017-0408-3

摘要：

It is costly and time consuming to use machining processes, such as grinding, polishing and lapping, to produce optical glass lenses with complex features. Precision glass molding (PGM) has thus been developed to realize an efficient manufacture of such optical components in a single step. However, PGM faces various technical challenges. For example, a PGM process must be carried out within the super-cooled region of optical glass above its glass transition temperature, in which the material has an unstable non-equilibrium structure. Within a narrow window of allowable temperature variation, the glass viscosity can change from 10⁵ to 10¹² Pa·s due to the kinetic fragility of the super-cooled liquid. This makes a PGM process sensitive to its molding temperature. In addition, because of the structural relaxation in this temperature window, the atomic structure that governs the material properties is strongly dependent on time and thermal history. Such complexity often leads to residual stresses and shape distortion in a lens molded, causing unexpected changes in density and refractive index. This review will discuss some of the central issues in PGM processes and provide a method based on a manufacturing chain consideration from mold material selection, property and deformation characterization of optical glass to process optimization. The realization of such optimization is a necessary step for the Industry 4.0 of PGM.

关键词： precision glass molding optical lens constitutive modeling optimization manufacturing chain Industry 4.0

HTML PDF 收藏

density measurement for plastic injection molding via ultrasonic technology

《机械工程前沿（英文）》 2022年第17卷第4期 doi: 10.1007/s11465-022-0714-2

摘要： Density variation during the injection molding process directly reflects the state of plastic melt and contains valuable information for process monitoring and optimization. Therefore, in-situ density measurement is of great interest and has significant application value. The existing methods, such as pressure−volume−temperature (PVT) method, have the shortages of time-delay and high cost of sensors. This study is the first to propose an in-situ density measurement method using ultrasonic technology. The analyses of the time-domain and frequency-domain signals are combined in the proposed method. The ultrasonic velocity is obtained from the time-domain signals, and the acoustic impedance is computed through a full-spectral analysis of the frequency-domain signals. Experiments with different process conditions are conducted, including different melt temperature, injection speed, material, and mold structure. Results show that the proposed method has good agreement with the PVT method. The proposed method has the advantages of in-situ measurement, non-destructive, high accuracy, low cost, and is of great application value for the injection molding industry.

关键词： ultrasonic measurement melt density in-situ measurement injection molding

HTML PDF 收藏

Microcellular injection molding process for producing lightweight thermoplastic polyurethane with customizable

Thomas ELLINGHAM, Hrishikesh KHARBAS, Mihai MANITIU, Guenter SCHOLZ, Lih-Sheng TURNG

《机械工程前沿（英文）》 2018年第13卷第1期页码 96-106 doi: 10.1007/s11465-018-0498-6

摘要：

A three-stage molding process involving microcellular injection molding with core retraction and an “out-of-mold” expansion was developed to manufacture thermoplastic polyurethane into lightweight foams of varying local densities, microstructures, and mechanical properties in the same microcellular injection molded part. Two stages of cavity expansion through sequential core retractions and a third expansion in a separate mold at an elevated temperature were carried out. The densities varied from 0.25 to 0.42 g/cm³ (77% to 62% weight reduction). The mechanical properties varied as well. Cyclic compressive strengths and hysteresis loss ratios, together with the microstructures, were characterized and reported.

关键词： thermoplastic polyurethane microcellular injection molding cavity expansion compressive strength hysteresis loss ratio

HTML PDF 收藏

Recent advancements in optical microstructure fabrication through glass molding process

Tianfeng ZHOU,Xiaohua LIU,Zhiqiang LIANG,Yang LIU,Jiaqing XIE,Xibin WANG

《机械工程前沿（英文）》 2017年第12卷第1期页码 46-65 doi: 10.1007/s11465-017-0425-2

摘要：

Optical microstructures are increasingly applied in several fields, such as optical systems, precision measurement, and microfluid chips. Microstructures include microgrooves, microprisms, and microlenses. This paper presents an overview of optical microstructure fabrication through glass molding and highlights the applications of optical microstructures in mold fabrication and glass molding. The glass-mold interface friction and adhesion are also discussed. Moreover, the latest advancements in glass molding technologies are detailed, including new mold materials and their fabrication methods, viscoelastic constitutive modeling of glass, and microstructure molding process, as well as ultrasonic vibration-assisted molding technology.

关键词： optical microstructure microgroove microlens glass molding process single-point diamond cutting

HTML PDF 收藏

气辅注塑成型注气压力的模糊神经网络控制研究

欧长劲

《中国工程科学》 2007年第9卷第5期页码 27-32

摘要：

针对气辅注塑成形的注气压力精确控制要求，设计了具有５层结构的模糊神经网络控制器和控制算法，利用神经网络的学习能力实现对模糊逻辑规则的优化，改善了系统的适应性。对系统３段压力控制的仿真分析，验证了模糊神经网络控制模型的可行性，控制效果良好。

关键词：气体辅助注射成型模糊神经网络注气压力控制

HTML PDF 收藏

Characterization of aerodynamic performance of wind-lens turbine using high-fidelity CFD simulations

Islam HASHEM, Aida A. HAFIZ, Mohamed H. MOHAMED

《能源前沿（英文）》 2022年第16卷第4期页码 661-682 doi: 10.1007/s11708-020-0713-0

摘要： Wind-lens turbines (WLTs) exhibit the prospect of a higher output power and more suitability for urban areas in comparison to bare wind turbines. The wind-lens typically comprises a diffuser shroud coupled with a flange appended to the exit periphery of the shroud. Wind-lenses can boost the velocity of the incoming wind through the turbine rotor owing to the creation of a low-pressure zone downstream the flanged diffuser. In this paper, the aerodynamic performance of the wind-lens is computationally assessed using high-fidelity transient CFD simulations for shrouds with different profiles, aiming to assess the effect of change of some design parameters such as length, area ratio and flange height of the diffuser shroud on the power augmentation. The power coefficient ( ) is calculated by solving the URANS equations with the aid of the SST model. Furthermore, comparisons with experimental data for validation are accomplished to prove that the proposed methodology could be able to precisely predict the aerodynamic behavior of the wind-lens turbine. The results affirm that wind-lens with cycloidal profile yield an augmentation of about 58% increase in power coefficient compared to bare wind turbine of the same rotor swept-area. It is also emphasized that diffusers (cycloid type) of small length could achieve a twice increase in power coefficient while maintaining large flange heights.

关键词： shroud diffuser-augmented wind turbine (DAWT) Betz limit aerodynamics computational fluid dynamics (CFD)

HTML PDF 收藏

用于毫米波焦面阵成像系统的扩展半球介质透镜

孙忠良,窦文斌

《中国工程科学》 2000年第2卷第3期页码 42-47

摘要：

毫米波成像是近年来毫米波领域的一个研究热点，而焦面阵成像因其具有实时成像的优点更加受到重视。文中分析可用于焦面阵成像的扩展半球介质透镜。这种焦面阵成像结构将集成天线阵贴附在透镜背面接收透镜聚焦的功率，消除了集成天线工作在毫米波频段时存在的表面波对天线性能的影响，具有尺寸紧凑、损耗小的特点。采用Stmtton-Chu公式和射线追迹分析了电磁波人射到扩展半球透镜上时在其背面的场分布，即透镜的焦区场分布，以获得透镜用于焦面阵成像时的性能。为验证分析方法的正确性，对平面波垂直人射和会聚高斯束入射两种情形进行了实验验证，实验结果与理论分析吻合较好。该透镜天线还可用来消除常规集成毫米波系统中抛物面天线与集成前端之间的过渡，以降低损耗，改善系统性能，也可用于与准光系统的连接或耦合。该文结果将对上述应用提供理论指导。

关键词：毫米波天线成像扩展半球介质透镜

HTML PDF 收藏

Three-dimensional numerical simulation for plastic injection-compression molding

Yun ZHANG, Wenjie YU, Junjie LIANG, Jianlin LANG, Dequn LI

《机械工程前沿（英文）》 2018年第13卷第1期页码 74-84 doi: 10.1007/s11465-018-0490-1

摘要：

Compared with conventional injection molding, injection-compression molding can mold optical parts with higher precision and lower flow residual stress. However, the melt flow process in a closed cavity becomes more complex because of the moving cavity boundary during compression and the nonlinear problems caused by non-Newtonian polymer melt. In this study, a 3D simulation method was developed for injection-compression molding. In this method, arbitrary Lagrangian-Eulerian was introduced to model the moving-boundary flow problem in the compression stage. The non-Newtonian characteristics and compressibility of the polymer melt were considered. The melt flow and pressure distribution in the cavity were investigated by using the proposed simulation method and compared with those of injection molding. Results reveal that the fountain flow effect becomes significant when the cavity thickness increases during compression. The back flow also plays an important role in the flow pattern and redistribution of cavity pressure. The discrepancy in pressures at different points along the flow path is complicated rather than monotonically decreased in injection molding.

关键词： injection-compression molding simulation injection molding melt flow cavity pressure

HTML PDF 收藏

Micro-optical fabrication by ultraprecision diamond machining and precision molding

Hui LI, Likai LI, Neil J. NAPLES, Jeffrey W. ROBLEE, Allen Y. YI

《机械工程前沿（英文）》 2017年第12卷第2期页码 181-192 doi: 10.1007/s11465-017-0444-z

摘要：

Ultraprecision diamond machining and high volume molding for affordable high precision high performance optical elements are becoming a viable process in optical industry for low cost high quality microoptical component manufacturing. In this process, first high precision microoptical molds are fabricated using ultraprecision single point diamond machining followed by high volume production methods such as compression or injection molding. In the last two decades, there have been steady improvements in ultraprecision machine design and performance, particularly with the introduction of both slow tool and fast tool servo. Today optical molds, including freeform surfaces and microlens arrays, are routinely diamond machined to final finish without post machining polishing. For consumers, compression molding or injection molding provide efficient and high quality optics at extremely low cost. In this paper, first ultraprecision machine design and machining processes such as slow tool and fast too servo are described then both compression molding and injection molding of polymer optics are discussed. To implement precision optical manufacturing by molding, numerical modeling can be included in the future as a critical part of the manufacturing process to ensure high product quality.

关键词： ultraprecision machining slow tool servo fast tool servo compression molding injection molding microlens arrays optical fabrication

HTML PDF 收藏

基于超构表面等离激元透镜的高速并行近场直写纳米光刻系统 Article

胡跃强, 李苓, 王榕, 宋剑, 王鸿栋, 段辉高, 纪佳馨, 孟永钢

《工程（英文）》 2021年第7卷第11期页码 1623-1630 doi: 10.1016/j.eng.2020.08.019

摘要：

具有简单、高效、低成本和高灵活性等特点的纳米加工技术在纳米尺度基础研究和原型验证中不可或缺。研究已证明，采用表面等离激元的近场光刻技术（即等离激元光刻）是一种有前景的解决方案。基于高速旋转基底上高刚度被动纳米间隙控制的加工系统是其中一种高效率加工方案。但是，为了研发出新一代具有高分辨率且可靠高效的纳米加工技术，需要探索一种更小更稳定的纳米间隙和新型等离激元透镜及其并行加工方案。因此，本文设计了一套并行等离激元直写纳米光刻系统。该系统应用了新型等离子浮动磁头，当转速为8~18 m⋅s⁻¹时，其最小飞行高度可实现15 nm并且具有高平行度。本文还研制了一种多级的基于超构表面的偏振不敏感等离激元透镜。与传统的等离激元透镜相比，该透镜耦合的功率更大，焦点的范围更集中。该原型系统实现了约26 nm最小线宽的纳米结构并行光刻。该系统有望应用于高自由级、低成本的纳米加工技术，如平面光学元件和纳米机电系统。

关键词：纳米加工表面等离激元光刻等离子体飞行头超构表面

HTML PDF 收藏

微型罗特曼透镜在无线通信中的应用 Research Articles

Bao-hua SUN, Qiu-yan LIANG, Gao-nan ZHOU

《信息与电子工程前沿（英文）》 2020年第21卷第1期页码 144-158 doi: 10.1631/FITEE.1900501

摘要：罗特曼透镜是一种具有实时延迟特性、多波束性能和宽带等优点的波束成形网络，在当今无线通信系统中得到广泛应用。然而，在无线通信系统中，传统罗特曼透镜尺寸相当大，可能会影响其与基站天线的集成。介绍3种微型化罗特曼透镜技术（切比雪夫阻抗变换器、功率分配器和带能量分配槽的截断端口）设计透镜，减小端口尺寸，从而减小罗特曼透镜所占总面积。仿真和测量结果表明，该方法可实现透镜主体与馈线之间良好的阻抗匹配。利用该带能量分配槽的截断端口，可大大减小罗特曼透镜尺寸，同时不降低透镜性能或增加生产成本。此外，研究了该微型罗特曼透镜在无线通信系统中两种可能的应用。罗特曼透镜不仅可沿阵列端口提供多个相位差信号实现多波束，还可生成平顶辐射等高性能成形波束。

关键词：罗特曼透镜；微型化；多波束；波束形成器；无线通信

HTML PDF 收藏

数值凸透镜——实现兆瓦级电力电子系统广义混杂动力学行为的状态离散建模解算 Article

施博辰, 赵争鸣, 朱义诚, 虞竹珺, 鞠佳禾

《工程（英文）》 2021年第7卷第12期页码 1766-1777 doi: 10.1016/j.eng.2021.07.011

摘要：

建模仿真已经成为构建虚拟数值实验平台和分析研究复杂工程系统必不可少的基础方法。然而，随着工程领域面对的系统越来越复杂，建模仿真方法也面临越来越大的挑战。这些复杂系统内部的动力学过程不仅包括连续状态，还包括离散事件，而且其动态过程跨越多个时间尺度。本文将这类复杂系统定义为“广义混杂系统”。兆瓦级电力电子系统是一类典型的广义混杂系统，已经被广泛应用于现代电网等多个关键领域，然而其建模解算仍然是一个瓶颈问题：要么计算时间太长，要么仿真不能收敛。为解决这一瓶颈问题，本文提出一种数值凸透镜方法，实现了广义混杂系统基于状态离散的建模解算。这一方法将传统的面向纯连续系统的时间离散仿真方法转变为面向广义混杂系统的状态离散仿真方法。本文将这一方法应用于一个面向新能源发电的大规模兆瓦级电力电子变换系统，与目前的通用仿真软件相比解算速度提高了1000倍。与此同时，所提方法首次实现了这一兆瓦级系统的开关瞬态仿真，仿真结果与实验测试结果相吻合，且仿真没有收敛性问题。本文提出的数值凸透镜方法实现了复杂的广义混杂系统多时间尺度动力学行为的高效建模解算，提升了工程领域基于虚拟数值实验认知和分析复杂动力学系统的能力。

关键词：广义混杂系统兆瓦级电力电子建模仿真数值凸透镜

HTML PDF 收藏

气辅成型工艺参数对制品成型质量的影响趋势研究

邱水金,姜少飞 ,柴国钟,鲁聪达

《中国工程科学》 2009年第11卷第4期页码 84-90

摘要：

对截面形状为s-3的加强筋进行工艺参数优化分析，讨论了气辅成型工艺参数对成型质量的影响程度，获得了一组较好的工艺参数组合。以此为参考标准，改变某一个工艺参数而保持其他工艺参数不变，对比研究4种不同截面形状加强筋在气辅成型条件下的成型情况，并考察了单个工艺参数对成型质量的影响趋势情况。

关键词：气体辅助注射成型加强筋正交试验设计

HTML PDF 收藏

Intelligent methods for the process parameter determination of plastic injection molding

Huang GAO, Yun ZHANG, Xundao ZHOU, Dequn LI

《机械工程前沿（英文）》 2018年第13卷第1期页码 85-95 doi: 10.1007/s11465-018-0491-0

摘要：

Injection molding is one of the most widely used material processing methods in producing plastic products with complex geometries and high precision. The determination of process parameters is important in obtaining qualified products and maintaining product quality. This article reviews the recent studies and developments of the intelligent methods applied in the process parameter determination of injection molding. These intelligent methods are classified into three categories: Case-based reasoning methods, expert system-based methods, and data fitting and optimization methods. A framework of process parameter determination is proposed after comprehensive discussions. Finally, the conclusions and future research topics are discussed.

关键词： injection molding intelligent methods process parameters optimization