微小塑料铰链模内装配注射模设计

分析了采用模内装配技术注射成型微小塑料铰链的工艺特点及其所面临的难题,通过优化微小塑料铰链的结构,合理安排塑件的成型顺序以及塑件的浇口位置和分型面,提出了一种能够有效避免模具微细型芯在聚合物熔体高压作用下发生弯曲变形的成型方案。依据这一成型方案和实验室的设备条件,设计了一副能够在单料筒微注塑机上使用的模内装配技术注射成型微小塑料铰链的模具,不仅解决了微小塑料铰链的塑件之间难以产生运动间隙的问题,而且降低了对成型设备的要求。     

极薄带微轧制技术研究与应用新进展

随着3C产品微型化和微制造技术兴起,在电子、计算机、医疗、能源、交通等相关行业对高质量金属极薄带出现了现实需求和迫切期待,极薄带微轧制生产与研究成为本行业的新热点。介绍了极薄带材的研究、生产和应用状况,分析了极薄带微轧制条件和变形特点,介绍了东北大学极薄带课题组研究工作的新进展,探讨了极薄带微轧制生产与研究的发展方向。     

齿轮模具电火花展成加工研究

从整体上对齿轮模具电火花展成加工方法进行研究,充分利用电火花加工不受工件硬度限制的优点,结合展成法加工齿轮的强制啮合原理,能均化各齿的加工误差,无轴向进给电火花加工所形成的加工锥度。实验证明,加工的齿轮模具完全能满足使用要求。齿轮模具电火花展成加工是齿轮加工方法的一个创新,对齿轮模具制造具有较大的现实意义。     

Dieless incremental micro-forming of miniature shell objects of aluminum foils

Single-point incremental forming of thin aluminum foils, which did not require any die and any backing plate, was developed for fabricating customized parts of thin shell miniature objects. Thin aluminum foils were deformed incrementally using a round-tip single point tool on a desktop type of milling machine controlled with a personal computer. It was found that an aluminum foil 12 μm thick was much smaller in forming limit than an aluminum foil 50 μm thick when a single point tool with a tip radius of 0.5 mm was not rotated, but its forming limit was improved greatly by rotating the tool up to 20,000 rpm. Measured forming forces revealed that the tool rotation decreases the in-plane forces by approximately 50%. Hydrodynamic lubrication at the interface between a rotating tool and aluminum foil must have had a direct and favorable influence on the forming process, while increasing the forming limit of the thinner foil. It was also found that the optimum stepwise axial feed was found to be around the value of foil thickness. Then, incremental forming of arrays of dots 0.1 mm in diameter, miniature pyramids, a miniature car and miniature letters was performed successfully under the optimized conditions at arbitrary positions of 12-μm-thick foils.     

基于ActiveX和MPI优化注射成型保压压力

运用ActiveX技术实现VB对MPI软件的有效控制,开发出优化注射成型保压压力的程序,自动为用户提供2种保压方式:先恒压后线性递减保压和先恒压后阶梯降压保压供用户选择。先恒压后线性递减保压方式较有利于提高塑件的表面质量。当注塑机不能很好实现保压压力线性递减或塑件壁厚变化较大时,则应采用先恒压后阶梯降压保压方式。确定保压方式后优化程序将根据MPI分析结果确定保压时间和保压压力,让用户能快速确定保压参数。     

Analysis of friction between stainless steel sheets and machine hammer peened structured tool surfaces: experimental and numerical investigation of the lubricated interaction gap

Forming of stainless steel with stringent requirements on surface integrity is currently realized using protective foils as a separating agent between tools and workpiece. The protective foils are applied with special machines and need to be removed after the forming process or at the end customer. This approach has pronounced economic and ecological disadvantages. Alternative tribological systems for a foil free forming are insufficiently researched and not yet reliably applicable in a production process. Recent developments in the field of machine hammer peening motivate the investigation of surface modifications for foil free sheet metal forming. The research question of this paper is: under which tribological boundary conditions do structured tool surfaces provide a total separation of tools and workpiece? The performed research work is based on experimental analyses investigating the friction behavior of surface structured tools. Numerical simulations of normal and sliding contact using finite element method enable the investigation of the lubricated interaction gap in order to identify significant tribological process parameters.     

基于CPAC的节能化注塑机控制系统开发

节能将是工业发展的必然趋势,针对鞋模注塑机工作循环中能耗大的特点,提出一种新型鞋模注塑机液压系统。重点阐述了新型鞋模注塑机的节能改造和基于CPAC(Computer Programmable Automation Controller)注塑机控制系统的开发。新型注塑机采用的是直驱式电液伺服系统,通过伺服电机来动态调节定量泵的转速,实现压力和流量两者都是闭环控制,从而达到节能的目的。控制系统采用以HMI为人机交互界面、固高GUC系列通用一体化控制器为控制核心,利用ST语言和梯形图(LD)两种语言开发了开放式模块化注塑机控制系统。     

Laser keyhole micro welding of aluminum foils to lap joints even with large gap sizes

The increasing miniaturization of components leads to increasing demands on manufacturing processes. High-brilliance lasers allow fast, low-heat deep penetration laser welding to produce narrow seams even in metal foils. In micro-joining, adjusting comparatively small gaps is a major challenge. Here, the welding of 100 µm thick aluminum foils in lap joints is investigated. Gaps of > 80% of the foil thickness were bridged. The results show that the seam width can be used to detect not only the gap size but also inner connection defects for quality control purposes. The explanation for this is the increasing gap-bridging keyhole depth, and thus heat input with increasing gap size.     

Oxidation resistance of aluminum-coated Fe-20Cr alloys containing rare earths or yttrium

Aluminum-coated Fe-20Cr-(rare earth or yttrium) alloy foils were developed with oxidation resistance equivalent or superior to Fe-20Cr-5Al-(rare earth or yttrium) alloy foils. The coated foils were made by dipping Fe-20Cr sheet into a salt-covered aluminum bath and then rolling the sheet to foil. Oxidation resistance of the coated foil was enhanced by adding rare earths or yttrium to the Fe-20Cr substrate alloys to insure oxide adherence. Test results indicate that only sufficient addition to tie up sulfur as a stable sulfide is needed in the Fe-20Cr alloy. Aluminum-coated foils show lower oxide growth rates than similar Fe-Cr-Al alloys, most likely the result of fewer impurities (particularly Fe) is the coated foils' growing oxide scale.     

注射成型典型缺陷形成的原因及解决措施

对注射成型过程中常见的成型缺陷进行了分类,并从材料、模具、注塑机和工艺方面分析了缺陷产生的原因,进而提出解决措施。     

锂电池中铝箔表面形貌对电池性能的影响

10～20μm厚的铝箔经常应用于锂电池的阴极。将被化学腐蚀的粗糙表面铝箔与光滑平面的铝箔进行对比,以考察铝箔的表面形貌对锂电池的影响。对于高电导率且颗粒较大的LiCoO2锂电池材料,两种铝箔的锂电池性能没有明显不同。但是对于低电导率且颗粒较小的LiFePO4材料,高倍率放电性有很大的差异。通过优化铝箔的表面形貌及电池材料的颗粒尺寸,可使电池的性能得到提高。     

Robust parameter design of micro-injection molded gears using a LIGA-like fabricated mold insert

Micro-injection molding, with advantages of easy mass production and low cost, is a key technology for producing micro components. Nevertheless, a low yield rate of high-quality molded parts is common due to problems associated with geometric precision, molecular orientation, and optical properties. Solutions to such problems must consider the machine, mold design, and process parameter settings. However, optimal performance becomes relatively less attainable when process parameters deviate due to inevitable process tolerances and change in an operation environment. This study has two goals: (1) fabrication of high-precision mold inserts using UV-LIGA; and, (2) identification of robust parameters that ensure production quality. Two gear mold-inserts with outside diameters of approximate 6 mm and 4 mm, named as the 6 mm and 4 mm gears, are introduced. First, lithography of thick photoresist SU8-50 is utilized as the initial structure seed layer to electroform the Ni gear mold insert. Second, this study investigates two key geometrical dimensions-the outside diameter and tooth thickness of the molded gears. The robust optimization of multiple objectives is introduced to identify robust parameter settings with high dimensional accuracy and high yield rates for molded gears despite process parameter deviations. Experimental results indicate that electroformed Ni mold inserts have good quality and are successfully utilized in the subsequent micro-injection molding process, demonstrating the feasibility of the mold inserts fabricated using UV-LIGA. The micro-injection molding experiments suggest that mold temperature, holding pressure, and injection speed have significant effects on dimensional quality characteristics of molded gears. The robust parameters derived from the proposed method increase yield rates of the 6 mm gear from 10% to 91%, and those of the 4 mm gear from 38% to 93% in comparison with the initial point, thereby demonstrating application effectiveness.     

基于模糊神经网络的注塑机注射缸位置控制研究

针对注塑机注射缸非线性和时变的特点,设计了基于模糊神经网络的复合控制器,并将其应用于高速注塑机注射缸的位置控制.实验结果表明:在注射缸高速变轨迹运动情况下,采用该控制器可获得比常规PID控制更高的位置跟踪精度.研究结论可为高速高精密液压注塑机设计提供参考.     

全闭环控制注塑机的关键技术研究

在综合分析注塑机控制技术发展存在问题以及相关专利的基础上,研究了注塑机的工作循环和注塑过程的三个主要阶段以及影响注塑产品表面质量的主要因素,从总线技术、高速动态响应、模糊控制及电机驱动优化4个方面提出了注塑机全闭环控制的关键技术。结果表明:通过对NCUC-Bus总线协议的应用层进行重新定义,实现了注塑机的压力、位置全闭环控制以及高速动态响应控制和高精度温度控制;通过模糊参数的自寻优得到了全闭环位置控制和全闭环压力控制的边界条件,平滑过渡了二者的切换过程,鲁棒性能良好;同时对交流永磁同步伺服电机优化控制提出了高响应带宽拓宽技术,高刚性抗扰技术,伺服电机在线参数辨识、自整定技术3个实现途径,从而提高了注塑机的性能指标。     

Influences of pulsed power condition on the machining properties in micro EDM

Micro EDM is one of the most powerful technologies which are capable of fabricating micro-structure. However, there are many operating parameters that affect the micro EDM process. Since the EDM is basically a thermal process, the supplying electrical condition can be an important factor. The conditions generally consist of several parameters such as electrical current, voltage, pulse duration, spark gap, and others. Those are decisive in removal rate, wear rate, and machining accuracy, which are characteristics of EDM. In this study, the influences of EDM pulse condition on the micro EDM properties were investigated. Voltage, current, and on/off time of the pulse were selected as experimental parameters based on a simple equation for the material removal rate. The pulse condition is particularly focused on the pulse duration and the ratio of off-time to on-time, and the machining properties are reported on tool wear, material removal rate, and machining accuracy. The experimental results show that the voltage and current of the pulse exert strongly to the machining properties and the shorter EDM pulse is more efficient to make a precision part with a higher material removal rate.     

Influences of cube texture on etched foil capacitance

The influences of aluminum cube texture on etched foil qualities and current efficiency were studied in this paper. The present results indicated that the decrease of cube texture (volume fraction) would lead to the decrease of tunnel densities on etched foils. Current efficiency changed little with cube texture and could reach up to 98%. The same current efficiency led to the same electrochemical corrosion weight loss, which caused the etched foils with a smaller tunnel density had a larger tunnel size. The same electrochemical corrosion weight loss would also lead to the etched foils produced by different cube texture foil have the same folding endurance. The etched foil produced by the foil with a better cube texture would have a larger tunnel density, which caused the capacitance of it was larger.     

高速注塑机注射部件设计及应用

针对高速注塑成型机特点,提出其注射部件的一般设计原则,并对注射部件动力源--蓄能器有关参数进行计算,分析注射部件液压系统原理,同时介绍高速注塑成型机的发展及应用.     

基于网络的注塑机液压远程监控系统研究

利用AMESim仿真软件实现注塑机液压系统的仿真模拟,并运用图形化编程语言LabVIEW作为搭建Web服务器的工具,两者相结合搭建了液压系统监控系统,通过内网穿透技术实现真正意义上的远程监控,旨在解决实际维护时人员不在现场,维护效率低,从而影响生产进度的问题。测试结果表明：所设计的注塑机远程监控系统性能可靠稳定,可实现无人值守,对注塑机的出售和升级换代起到非常积极的作用。     

Mechanical properties of the weld line defect in micro injection molding for various nano filled polypropylene composites

The nano filled functional polymer materials have been widely processed with micro injection molding technology for micro electromechanical systems (MEMS) fabrication. As the unfavorable defect in micro injection molding parts, weld line brings reduced mechanical and physical properties, especially for nano filled composites. In this study, polypropylene (PP) was compounded respectively with carbon nano fibers (CNFs) and TiO₂ nano particles at various weight fractions (10, 20, 30, 35 wt%) through co-screws internal mixing. The morphological, thermal and rheological properties of nano composites were characterized by wider angle X-ray diffraction (WXRD), different scanning calorimeter (DSC) and high pressure capillary rheometer. Additionally, under the constant setting of injection molding process parameters in injection molding machine, micro tensile samples with weld lines for each nano filled PP composite were produced. The tensile tests were served as the characterizing method for weld line mechanical properties. The results show that when the CNFs is filled higher than 10 wt%, the tensile strength of samples with weld lines made of nano composites become lower than neat PP. While the raising CNFs content contributes to the improved E modulus of micro injection molded weld lines. Additionally, with the increasing fraction of CNFs in PP, the weld line area's elongation percent is decreased. Whereas for case of TiO₂, the 10 wt% is the threshold for micro injection molded weld line tensile strength turning from decrease trend to increase. The same as CNFs, elongation of micro weld line samples were in general lower than neat PP as well, due to the addition of TiO₂ nano particles.     

混粉电火花加工技术在粗加工中的应用研究

在对混粉电火花加工机理进行系统研究的基础上，对混粉电火花粗加工中的加工效率和加工表面粗糙度进行了实验研究。结果表明，通过合理选择放电参数，混粉电火花加工在相近加工表面粗糙度时，能显著提高加工效率，从而为混粉电火花加工技术在粗加工中应用提供依据。