室温快速固化高性能环氧树脂胶粘剂研究

为了提高胶粘剂在室温条件下的固化速度,并改善其力学性能,研究了固化剂含量、填料含量对环氧树脂胶粘剂固化速度和力学性能的影响.结果表明,当固化剂含量为95～100 phr,填料含量为60～ 80 phr时,胶粘剂的综合性能最好;该新型胶粘剂在室温12 min即可快速固化,剪切强度可达13.8 MPa,拉伸强度和弯曲强度分别达到了43.1MPa和83.2 MPa.     

基于环氧树脂快速制模技术鞋底模具的制造

分析了环氧树脂模具的制造流程,研究了鞋底环氧树脂快速模具的制造技术.经生产实践证明,应用环氧树脂快速模具可以缩短产品开发周期,并可获得满意的结果.     

环氧树脂胶粘剂微波固化研究

利用自主研制的腔外加热式微波设备固化环氧树脂胶粘剂,采用差示扫描量热分析(DSC)、红外光谱(FT-IR)及扫描电子显微镜(SEM)分析方法,考察了微波与加热两种固化方式下环氧树脂胶粘剂的固化行为.结果表明:微波固化不能改变固化的最终产物,但能显著提高胶粘剂的固化速度,在固化转化率相同的情况下,微波固化时间是加热固化的1/24;微波能有效改善纳米粉体与树脂基体之间的相容性,提高界面结合性能.     

快速成形及其在快速制模中的应用

快速成形（ＲＰ＆Ｍ）作为一种新兴的先进制造技术,已成功地实现了快速原型制造,正向快速制模（ＲＴ）方向迅速发展。本文介绍了快速成形技术的现状及其在快速制模尤其是快速金属模具制造方面的应用,探讨了制约快速制模技术发展的关键问题和该技术的发展趋势。     

激光固化快速成型树脂加热器的研究

对激光固化快速成型技术进行了简单阐述,介绍分析了树脂加热的两种主要的加热器,提出了一种热风加热器的设计方案,此方案在实际应用中能较好地满足使用要求,具有一定的工程意义。     

抗震底座树脂模具强度研究

SLS技术处理后的烧结件用于模具时,为提高树脂模具的强度,对影响树脂模具强度的树脂混合液涂料质量、涂抹时间和涂抹后的固化处理工艺进行研究。试验表明,受树脂混合液涂料成分的影响,树脂混合液涂料应在45min内均匀涂抹在烧结件上;不同的烧结件所需要的树脂混合液涂料质量也有所不同;涂抹后的烧结件在常温下放置一段时间后再放入恒温干燥箱进行渐次升温固化处理可以明显提高树脂模具的强度。     

基于快速原型的硅橡胶模具快速制造技术

介绍了快速原型制造技术的主要方法、基本原理及主要应用领域,详细地描述了以叠层实体原型为母模快速翻制硅橡胶模具的制造工艺及其相关的技术细节。     

基于快速成型的制造冲压模具及产品的方法

对快速成型技术及Ｄｕａｌｆｏｒｍ 工艺作了简要的介绍,并在此基础上对二者各自的特点、优越性、适用范围及结合后可能产生的巨大效益和发展前景进行了论述及展望。     

基于快速原型的硅橡胶模具快速制造技术

介绍了快速原型制造技术的主要方法、基本原理及主要应用领域，详细地描述了以叠层实体原型为母模快速翻制硅橡胶模具的制造工艺及其相关的技术细节。     

Indentation experiment and analysis on mold and resin material during the nanoimprint process

Analysis and experiment on mold and resin materials for the nanoimprint process are conducted in this study. We developed FEM analysis of indentation stress induced in mold materials when they come in contact with 1MPa expanded uniaxial stress. Experimental analyses of viscosity, thermal expansion coefficient, and shrinkage rate of acrylate-based UV resin are likewise undertaken. Experimentally, Hertzian indentation and adhesion tests are used as model test systems for the micro/nanoimprint process. For the study, indentation test variables investigated are the contact load for various mold materials such as Si, glass, and PDMS(polydimethylsiloxane). The adhesion test is performed to measure the maximum uniaxial load required to separate the mold from the resin material. The results highlight that the adhesion stresses are not negligible during the demoulding process, while the indentation stresses are negligible during the imprint process. This paper was presented at the 4th Asian Conference on Multibody Dynamics(ACMD2008), Jeju, Korea, August 20–23, 2008. Kee Sung Lee received Ph.D. degrees from KAIST in 1998. He worked as a Post doctor of NIST, USA in 1999 and 2000. Dr. Lee is currently a Professor at the School of Mechanical and Automotive Engineering at Kookmin University in Seoul, Korea. Dr. Lee’s research interests are in the area of material and fracture.     

Effect of process induced variations on machining characteristics of a model epoxy resin system

The present work aims to understand the effect of process induced variation on mechanisms of failure, deformation and damage mechanisms in a model epoxy resin system during machining. Process variations have been introduced for a 5052 Huntsman epoxy resin system by considering three post-cure temperature and cycles, viz., 50°C for 15 h, 80°C for 8 h and 100°C for 4 h. Detailed orthogonal cutting experiments have been carried out at different cutting speeds, rake angles and uncut chip thicknesses. Studies of chip formation characteristics, cutting force signatures and fractography indicate a significant brittle-like behavior with increasing post-cure temperature resulting in discontinuous chips that became more pronounced for a positive rake angle. Concurrently, extensive mechanical characterization under different strain rates and temperatures has been carried out using dynamic mechanical analyzer for the epoxy specimens. In addition, standard tensile tests have also been conducted that indicate a correlation between mechanical properties and post-cure temperature cycles. Results are indicative of a strong correlation between post-cure variations and associated failure, fracture characteristics during machining that can be used as a tool for assessing the in-situ cure characteristics in a composite structure.     

Premature melt solidification during mold filling and its influence on the as-cast structure

Premature melt solidification is the solidification of a melt during mold filling. In this study, a numerical model is used to analyze the influence of the pouring process on the premature solidification. The numerical model considers three phases, namely, air, melt, and equiaxed crystals. The crystals are assumed to have originated from the heterogeneous nucleation in the undercooled melt resulting from the first contact of the melt with the cold mold during pouring. The transport of the crystals by the melt flow, in accordance with the socalled “big bang” theory, is considered. The crystals are assumed globular in morphology and capable of growing according to the local constitutional undercooling. These crystals can also be remelted by mixing with the superheated melt. As the modeling results, the evolutionary trends of the number density of the crystals and the volume fraction of the solid crystals in the melt during pouring are presented. The calculated number density of the crystals and the volume fraction of the solid crystals in the melt at the end of pouring are used as the initial conditions for the subsequent solidification simulation of the evolution of the as-cast structure. A five-phase volume-average model for mixed columnar-equiaxed solidification is used for the solidification simulation. An improved agreement between the simulation and experimental results is achieved by considering the effect of premature melt solidification during mold filling. Finally, the influences of pouring parameters, namely, pouring temperature, initial mold temperature, and pouring rate, on the premature melt solidification are discussed.     

Design optimization of clutch housing mold by fluid flow and solidification simulation

Aluminum die casting is so complex where flow momentum is critical matter in the mould filling process due the high velocity of the liquid metal. Actually, in complex parts the exact calculation of mould filling performance with using experimental knowledge is almost impossible. Aluminum die castings play a definitive role in the manufacturing of lightweight automobile bodies. Hence it is more essential today that these castings be produced with the high quality methods. In this condition the simulation is becoming more important in the designing procedure. This saves time and reduces the cost of the casting system design, which is an advantage of using simulation programs. Also, economical utilization of materials can be obtained when the quantity of test castings is decreased. This paper describes the advantages of the clutch housing die casting mold simulations to achieve better casting system design in High pressure die castings (HPDC). Filling analysis is used to determine the size and location of the gate as well as proper runner system design for ensuring a complete and balanced filling of the clutch housing part.

     

Prediction of solidification time during solidification of aluminum base alloy castings cast in CO2-sand mold

Solidification of molten metals during various casting methods poses many practical problems associated with phase transformation and heat transfer processes. Evaluation of solidification time is one of the very important parameters used for assessing the properties of the material. In the present study, experimental investigation was carried out to measure the solidification time in a cylindrical hollow casting cast in CO₂-Sand molds and the same has been compared with the results obtained through computed by using an implicit alternating direction (IAD) method, including the treatment of interfacial nodes between metal and mold, and boundary nodes at the mold surface. Aluminum-4.5% copper alloy has been used. Computed cooling curves at various locations and temperature distributions in core-metal-mold were presented. The results shows that the solidification time obtained by experimental study compares well with the one predicted by the analysis made through IAD modeling. A successful comparison with reported experimental results shows that the technique is appropriate for simulation of solidification process of aluminum castings.     

计算机辅助树脂传递模塑成型工艺系统研究

针对树脂传递模型工艺参数种类多、难以管理、数据不能共享的弊病,将基于事例推理的工艺设计方法应用于复合材料树脂传递模塑成型工艺中,提出了复合材料树脂传递模塑成型计算机辅助工艺设计的系统结构,给出了系统流程框架,研究了相似事例检索方法、增强体铺层参数和固化成型参数确定等关键技术。最后,采用面向对象和组件技术实现了该工艺系统,并通过实例验证了该系统的可行性。     

Research on thermal stress, deformation, and fatigue lifetime of the rapid heating cycle injection mold

Rapid heating cycle molding (RHCM) is a novel plastic injection molding process. It can be used effectively to prevent many defects of products produced in conventional injection molding process. In this paper, the panel of large-size liquid crystal display TV was taken as an example. Thermal, deformation, and fatigue analysis models for RHCM injection mold were established. Firstly, by analyzing the heat transfer process of the RHCM mold, the temperature distributions on the mold cavity surface were studied. Secondly, through numerical simulation, the tendency of the stress and deformation of the RHCM mold was obtained. It showed that the fixing mode between the stationary mold insert and the stationary mold plate had a great influence on the thermal stress and deformation of the mold. As a result, a new fixing mode for the stationary mold insert was proposed which could effectively decrease the deformation caused by the temperature changing. Lastly, the lifetime of the mold under different fixing modes was evaluated, and reasonable suggestions which could improve the lifetime of RHCM mold were also proposed. Application in engineering proved that it was a very effective way to improve the lifetime of RHCM mold by using the suggested fixing mode.     

基于DLP的珠宝树脂3D打印工艺研究

DLP(数字光处理技术)是一种以面曝光的方式逐层成型的3D打印技术.在DLP的3D打印工艺过程中,当分层厚度确定时,零件的打印精度主要取决于曝光时间和成型方向.设计一个测试试样,研究了采用DLP工艺打印珠宝树脂材料过程中的单层曝光时间和零件成型方向对不同特征打印精度的影响规律.研究结果表明:对于所采用的珠宝铸造树脂曝光...