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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    

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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    

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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    

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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    

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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    

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Numerical study of ignition mechanism of n-heptane direct injection compression-ignition engine

Xiaoping GUO, Zhanjie WANG,

《能源前沿（英文）》 2009年 第3卷 第4期   页码 432-439 doi: 10.1007/s11708-009-0050-9

摘要： A detailed chemical dynamical mechanism of oxidation of n-heptane was implemented into kiva-3 code to study the ignition mechanism of a high-temperature, high-pressure, three-dimensional-space, transient turbulent, non-homogeneous, mono-component fuel in the engine. By testing the quantity of the heat released by the chemical reaction within the cylinder cell, the elementary reaction showing an obvious increase in the cell temperature was defined as ignition reaction and the corresponding cell as ignition position. The main pathway of the ignition reaction was studied by using the reverse deducing method. The result shows that the ignition in the engine can be divided into low-temperature ignition and high-temperature ignition, both of which follow the same rule in releasing heat, called the impulse heat releasing feature. Low-temperature ignition reaction, whose ignition reaction is c5h9o1-4=ch3cho+c3h5-a, follows the oxidation mechanism, while high-temperature ignition reaction, whose ignition reaction is c2h3o1-2=ch3co, follows the decomposition mechanism. No matter which ignition it is in, the chemical reaction that restrains the ignition reaction from lasting is the deoxidization reaction of alkylperoxy radicals.

关键词： compression-ignition engine     ignition mechanism     elementary reaction     n-heptane    

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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    

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Control of homogeneous charge compression ignition combustion in a two-cylinder gasoline direct injection

WANG Zhi, WANG Jianxin, SHUAI Shijin, MA Qingjun, TIAN Guohong

《能源前沿（英文）》 2007年 第1卷 第3期   页码 311-315 doi: 10.1007/s11708-007-0045-3

摘要： Homogeneous charge compression ignition (HCCI) has challenges in ignition timing control, combustion rate control, and operating range extension. In this paper, HCCI combustion was studied in a two-cylinder gasoline direct injection (GDI) engine with negative valve overlap (NVO). A two-stage gasoline direct injection strategy combined with negative valve overlap was used to control mixture formation and combustion. The gasoline engine could be operated in HCCI combustion mode at a speed range of 800–2 200 r/min and load, indicated mean effective pressure (IMEP) range of 0.1–0.53 MPa. The engine fuel consumption is below 240 g/(kW

关键词： Homogeneous     control     combustion     consumption     extension    

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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    

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methodology for regulating fuel stratification and improving fuel economy of GCI mode via double main-injection

《能源前沿（英文）》 2023年 第17卷 第5期   页码 678-691 doi: 10.1007/s11708-022-0859-z

摘要： Gasoline compression ignition (GCI) combustion faces problems such as high maximum pressure rise rate (MPRR) and combustion deterioration at high loads. This paper aims to improve the engine performance of the GCI mode by regulating concentration stratification and promoting fuel-gas mixing by utilizing the double main-injection (DMI) strategy. Two direct injectors simultaneously injected gasoline with an octane number of 82.7 to investigate the energy ratio between the two main-injection and exhaust gas recirculation (EGR) on combustion and emissions. High-load experiments were conducted using the DMI strategy and compared with the single main-injection (SMI) strategy and conventional diesel combustion. The results indicate that the DMI strategy have a great potential to reduce the MPRR and improve the fuel economy of the GCI mode. At a 10 bar indicated mean effective pressure, increasing the main-injection-2 ratio (Rm-2) shortens the injection duration and increases the mean mixing time. Optimized Rm-2 could moderate the trade-off between the MPRR and the indicated specific fuel consumption with both reductions. An appropriate EGR should be adopted considering combustion and emissions. The DMI strategy achieves a highly efficient and stable combustion at high loads, with an indicated thermal efficiency (ITE) greater than 48%, CO and THC emissions at low levels, and MPRR within a reasonable range. Compared with the SMI strategy, the maximum improvement of the ITE is 1.5%, and the maximum reduction of MPRR is 1.5 bar/°CA.

关键词： gasoline compression ignition     injection strategy     fuel stratification     high efficiency     high load    

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Improvement of engine performance with high compression ratio based on knock suppression using Millercycle with boost pressure and split injection

Haiqiao WEI, Jie YU, Lei ZHOU

《能源前沿（英文）》 2019年 第13卷 第4期   页码 691-706 doi: 10.1007/s11708-019-0621-3

摘要： In theory, high compression ratio has the potential to improve the thermal efficiency and promote the power output of the SI engine. However, the application of high compression ratio is substantially limited by the knock in practical working process. The objective of this work is to comprehensively investigate the application of high compression ratio on a gasoline engine based on the Miller cycle with boost pressure and split injection. In this work, the specific optimum strategies for CR10 and CR12 were experimentally investigated respectively on a single cylinder DISI engine. It was found that a high level of Miller cycle with a higher boost pressure could be used in CR12 to achieve an effective compression ratio similar to CR10, which could eliminate the knock limits at a high compression ratio and high load. To verify the advantages of the high compression ratio, the fuel economy and power performance of CR10 and CR12 were compared at full and partial loads. The result revealed that, compared with CR10, a similar power performance and a reduced fuel consumption of CR12 at full load could be achieved by using the strong Miller cycle and split injection. At partial load, the conditions of CR12 had very superior fuel economy and power performance compared to those of CR10.

关键词： high compression ratio     knock     Miller cycle     split injection     engine performance    

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喷射策略对低负荷下天然气——柴油双燃料预混压燃燃烧的影响研究 Article

Hyunwook Park, Euijoon Shim, Choongsik Bae

《工程（英文）》 2019年 第5卷 第3期   页码 548-557 doi: 10.1016/j.eng.2019.03.005

摘要：

双燃料预混压燃（dual-fuel premixed charge compression ignition, DF-PCCI）燃烧因其氮氧化物（NOx）和颗粒物

关键词： 双燃料     反应可控压燃     预混压燃     天然气     喷射策略     废气再循环    

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Characteristics and energy distribution of modulated multi-pulse injection modes based diesel HCCI combustion

LIU Bin, SU Wanhua, WANG Hui, HUANG Haozhong

《能源前沿（英文）》 2007年 第1卷 第4期   页码 420-427 doi: 10.1007/s11708-007-0061-7

摘要： Cycle fuel energy distribution and combustion characteristics of early in-cylinder diesel homogenous charge compression ignition (HCCI) combustion organized by modulated multi-pulse injection modes are studied by the engine test.

关键词： combustion     compression     homogenous     in-cylinder     modulated multi-pulse    

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Performance and emission characteristics of QHCCI dimethyl ether engine

WANG Ying, LI Wei, ZHOU Longbao, LIU Shenghua, HU Tiegang

《能源前沿（英文）》 2008年 第2卷 第4期   页码 401-405 doi: 10.1007/s11708-008-0075-5

摘要： Experimental investigation into the effects of different pilot amounts of dimethyl ether (DME) on the performance and emission of a single-cylinder direct-injection DME engine is conducted. The results show that a DME engine can operate at a wider range of speeds and loads at quasi-homogenous charge compression ignition (QHCCI) mode. The brake thermal efficiency increases while the exhaust temperature decreases. NO emission decreases by about 30%–50% although there is a slight increase in HC and CO emissions. NO, HC and CO emissions increase with an increase in the amount of DME pilot. QHCCI is a good way to increase thermal efficiency and decrease NO emission.

关键词： Experimental investigation     single-cylinder direct-injection     exhaust temperature     dimethyl     compression ignition    

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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    

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标题 作者 时间 类型 操作

Three-dimensional numerical simulation for plastic injection-compression molding

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

期刊论文

density measurement for plastic injection molding via ultrasonic technology

期刊论文

Microcellular injection molding process for producing lightweight thermoplastic polyurethane with customizable

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

期刊论文

Micro-optical fabrication by ultraprecision diamond machining and precision molding

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

期刊论文

气辅注塑成型注气压力的模糊神经网络控制研究

欧长劲

期刊论文

Numerical study of ignition mechanism of n-heptane direct injection compression-ignition engine

Xiaoping GUO, Zhanjie WANG,

期刊论文

Intelligent methods for the process parameter determination of plastic injection molding

Huang GAO, Yun ZHANG, Xundao ZHOU, Dequn LI

期刊论文

Control of homogeneous charge compression ignition combustion in a two-cylinder gasoline direct injection

WANG Zhi, WANG Jianxin, SHUAI Shijin, MA Qingjun, TIAN Guohong

期刊论文

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

期刊论文

methodology for regulating fuel stratification and improving fuel economy of GCI mode via double main-injection

期刊论文

Improvement of engine performance with high compression ratio based on knock suppression using Millercycle with boost pressure and split injection

Haiqiao WEI, Jie YU, Lei ZHOU

期刊论文

喷射策略对低负荷下天然气——柴油双燃料预混压燃燃烧的影响研究

Hyunwook Park, Euijoon Shim, Choongsik Bae

期刊论文

Characteristics and energy distribution of modulated multi-pulse injection modes based diesel HCCI combustion

LIU Bin, SU Wanhua, WANG Hui, HUANG Haozhong

期刊论文

Performance and emission characteristics of QHCCI dimethyl ether engine

WANG Ying, LI Wei, ZHOU Longbao, LIU Shenghua, HU Tiegang

期刊论文

Review of small aspheric glass lens molding technologies

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

期刊论文