Effects of molding conditions on injection molded direct joining using a metal with nano-structured surface

Injection molded direct joining (IMDJ) is one of the metal-plastic direct joining processes and is based on a combination of a special surface treatment of a metal piece and an insert molding. This study employed a chemical processing as the special surface treatment to form nano-structures on the metal piece. We investigated relationship between joining strengths and molding conditions; we focused on pressure of a mold cavity and injection speed as molding conditions in this work. To evaluate the IMDJ samples processed under various molding conditions, we carried out tensile-shear tests. Then we compared the results of the tests to discuss how much each condition variation affected the joining strength. From the discussion, we found an interesting effect of the injection speed, which is unique to the IMDJ using a metal piece with nano-structures. The findings of this study will promote a better understanding of the IMDJ.     

Experimental analysis on mechanical interlocking of metal–polymer direct joining

Injection molded direct joining (IMDJ) is a method for direct joining of metals and polymers. In this work, we identified the most influential parameter for IMDJ and explained the reasons for successful joining by considering mechanical interlocking. We prepared hybrid joints of 30% glass-fiber-reinforced polybutylene terephthalate and aluminum alloy (A5052) plates with laser-treated surface dimples via IMDJ under various injection parameters. We studied the effects of the packing and holding pressures and the polymer temperatures on the joining strength. We discussed the reasons for the observed effects by considering mechanical interlocking, including the infiltration depth and the contact between the metal and the polymer. We found the packing pressure to be the most influential parameter. Moreover, the interaction between the packing pressure and the polymer temperature also influenced the joining strength considerably. The increased joining strength under various combinations of injection parameters was a result of deeper infiltration depth and better contact. We anticipate that the findings of this study will aid better selection of injection parameters for IMDJ.     

Experimental and simulative investigation of the effects of laser-structured metal surface on metal-polymer direct joining

Direct joining of metal and polymer consists of surface treatment and injection molding techniques. This study employed a laser machining as the surface treatment to form periodic dimples on a joining surface. We experimentally investigated the effect of surface structures on joining strength under a constant molding condition; we focused on the diameter, aspect ratio and periodicity of the dimple, and the surface texture on its inner wall. Furthermore, we analyzed the effect of the surface texture on the inner wall of the dimple on the joining strength with finite element method. We found that the joining strength became higher with increasing number of dimples when total machined area was same. Another finding was that the joining strength increased with increasing aspect ratio and was saturated above the aspect ratio of 0.6. Furthermore, the experimental and simulated results strongly suggested that roughness on the inner wall of the dimple played an important role to enhance the joining strength. The findings of this study will promote the optimization of the metal surface structure for the metal-polymer direct joining.     

金-塑微结构注射成型仿真与试验研究*

金属-塑料(聚合物)复合高强件具有强度高、质量小、易成型复杂结构等优点,在航空航天、汽车制造、通信等领域日益得到重视。介绍金-塑复合微结构注射成型原理,建立聚合物熔体在金属表面微结构填充流动的数值模型。采用两相流水平集方法追踪获得了微尺度下聚合物熔体在金属表面的流动前沿,研究金属表面微结构尺寸大小、注射速度和金属表面温度等参数对聚合物熔体填充微结构能力的影响规律,为实际产品的生产成形提供理论基础。根据金-塑复合件的成型理论与技术,构建金-塑复合成型试验装置,采用物理喷砂的方式制备了金属表面的微结构,并注射获得了金属-塑料成型的试验试样。通过对获得的试验试样进行拉伸剪切试验,验证了本文仿真结果的合理性。所取得的研究结果对优化金-塑成型工艺参数和改善产品质量有着重要的启发和指导意义。     

微结构模芯的精密磨削及其在微注塑成形中应用

针对微结构聚合物元器件的批量化生产与制造效率低等问题,采用精密修整成V形尖端的金刚石砂轮,在自润滑性和脱模性良好的钛硅碳陶瓷模芯表面加工制造出形状精度可控的V沟槽阵列结构,然后利用微注塑成形工艺将模芯表面的V沟槽阵列结构一次成形复制到聚合物表面,高效注塑成形制造出倒V形阵列结构的聚合物工件。分析了微模芯的表面加工质量与形状精度,研究了熔体温度、注射速度、保压压力、保压时间等微注塑成形工艺参数对微结构聚合物注塑成形角度偏差和填充率的影响。实验结果表明：通过微细磨削加工技术和微注塑成形工艺可以高效率、高精度地制造出规则整齐的微结构注塑工件,注射速度对微成形角度偏差的影响最大,保压压力对微成形填充率的影响最大,微结构模芯的微细磨削形状精度值为4.05 μm,微成形的最小角度偏差和最大填充率分别为1.47°和99.30%。     

聚合物微发泡成型新技术

微发泡成型技术是指以热塑性材料为基体,通过特殊的加工工艺,使制品中间层密布泡孔尺寸从小于一微米到几十微米尺寸的封闭微孔。微发泡注塑成型技术突破了传统注塑的诸多局限,在基本保证制品性能不降低的基础上,可以明显减轻制件重量和成型周期,大大降低设备的锁模力,并具有内应力和翘曲小,平直度高,没有缩水,尺寸稳定,成型视窗大等优势。与常规注塑相比较,特别在生产高精密以及材料较贵的制品中,在许多方面都独具优势,成为近年来注塑技术发展的一个重要方面。     

An investigation of the machinability of PA 6/nano-CaCO3 composite

Nowadays, polymer nanocomposites have attracted manufacturers’ attention because of their good mechanical, thermal, and physical properties. Over the past decade, the requirement of the direct machining of polymer nanocomposites has increased due to the production of most polymer nanocomposites using the extrusion method in simple cross-section and the increased demand for personalized products. In this paper, the effect of milling parameters (spindle speed and feed per tooth) and nano-CaCO₃ content on the machinability properties of PA 6/nano-CaCO₃ composites was studied by analyzing variance. Harmony search-based neural network (HSNN) was then utilized to create predictive models of surface roughness and total cutting forces from the experimental data. The results revealed that the nano-CaCO₃ content on PA 6 decreased the cutting forces significantly, but did not have a significant effect on surface roughness. Moreover, the results for modeling total cutting forces and surface roughness showed that HSNN is effective, reliable, and authoritative in modeling the surface roughness formation and total cutting force mechanism for end-milling of PA 6/nano-CaCO₃ composites.     

Mold surface roughness effects on cavity filling of polymer melt in micro injection molding

Micro injection molding presents many challenges in the injection-molding community. When the dimensions of the part (and thus the cavity of the mold) are small, micro-scale factors such as mold surface roughness may play an important role in the filling of polymer melt. This paper investigates the effects of mold surface roughness on cavity filling of polymer melt in micro injection molding. A disk insert, which has two halves with different surface roughness but with the same roughness mean lines, was used in the investigations. The ratio of flow area of the rougher half with the total flow area of the molded part is used to evaluate the significance of surface roughness effect. The experimental results revealed that mold surface roughness does resist the cavity filling of polymer melt in micro injection molding. For the limited range of injection rate investigated, it is not significant on the surface roughness effects. The increase of mold temperature will decrease surface roughness effects. The change of melt temperature within the range allowed by the process is insignificant for surface roughness effects.     

气辅成型中高压气体射流扩散特征分析

通过试验研究和理论分析,研究了气辅成型工艺中气体穿透聚合物熔体的扩散特征。结果表明,在气体注射点近区,气体对聚合物熔体冲击程度较大,呈现出复杂流动形态及扩散特征;当气泡穿透到离注气点一定距离后才趋于均匀;在气泡末端,由于气体的二次穿透作用而使气泡变得细而长。研究结果对于气辅工艺开发和气辅模具设计有重要指导意义。     

涉水工程装备用聚合物摩擦副材料改性技术研究进展

聚合物作为摩擦副材料在涉水工程装备上应用前景广阔,然而与金属材料相比,聚合物材料存在强度低、蠕变、老化以及吸水等固有缺陷,并且在低速重载工况下难以形成完整的润滑水膜而导致零部件出现严重的磨损与振动问题,随着涉水工程装备运动副所面临复杂多样的极端环境和苛刻工况,极大地限制了聚合物材料作为摩擦副部件在涉水工程装备领域的应用。分析了聚合物材料在涉水极端环境中的主要摩擦学问题和面临的挑战,并从辐照与等离子体表面改性技术、填料共混复合改性技术、织构化表面调控技术,以及功能化水润滑表面调控技术4个方面,综述目前国内外关于涉水工程装备用聚合物摩擦副材料改性技术的研究进展,最后对涉水工程装备用聚合物摩擦副材料的制备技术和摩擦学研究方向进行总结和展望。     

聚合物微器件压力自适应超声波精密联接

将超声波联接技术应用于聚合物微器件的联接,搭建了超声波精密联接系统。为了保证微器件在精密联接中的形状精度,选用工作频率为60 kHz的超声换能器及驱动电源为微器件提供高频、低振幅的超声波振动;以高细分步进电机驱动直线导轨控制超声波工具头的纵向移动,精确控制超声波工具头的位置,并结合力传感器实现了超声波联接过程中聚合物材料力学性能的实时检测。针对联接表面特性差异引起的联接质量不一致问题,提出了基于材料力学性能反馈的压力自适应联接方法,可以对不同零件提供自适应的超声波能量。应用该系统对PMMA材料微器件进行了联接实验,实验结果表明,该方法大幅提高了超声波联接的稳定性,实现了聚合物微器件的超声波精密联接。     

金属-聚合物复合件微纳结构注射成形分析与实验

基于金属-聚合物复合件的成形理论与技术,提出了通过改善金属表面的温度、微观结构和聚合物成形时的黏度、压力等因素,利用注射工艺直接成形金属-聚合物复合件的新方法。研究了金属表面微结构形成的3种方法与形成的表面微结构的特点,构建了金属表面温度控制装置和系统。利用构建的温控系统和制作的模具,获得了直接注射成形的金属-聚合物复合件,并分析了不同的金属表面微结构与金属-聚合物界面结合力学性能的对应关系,验证了直接注射成形金属-聚合物复合件工艺的可行性。     

碱处理剑麻纤维/聚丙烯复合材料的性能研究

选用氢氧化钠溶液对剑麻纤维(SF)进行表面改性,采用注塑成型的方法制备SF/聚丙烯(PP)复合材料,借助扫描电镜(SEM)观察碱处理效果及剑麻纤维在聚丙烯基体中的分散性,通过力学性能和摩擦磨损性能测试研究不同含量SF对复合材料性能的影响。结果表明:氢氧化钠质量分数为10%时可获得最佳的纤维处理效果,但仅用碱处理未在纤维与基体之间形成有效的化学结合。随着SF含量的增加,复合材料的拉伸强度和弹性模量增加,摩擦因数和磨损率下降,SF质量分数为20%时拉伸强度和弹性模量达到最大值,SF质量分数为10%时摩擦因数和磨损率达到最小值。     

阵列式微流道的粉末微注射成形技术

作为一种近净成形技术,粉末微注射成形具有低成本、高精度、高效率的特点,在成形微小型复杂形状的零件方面优势突出。文中详述了粉末微注射成形制备工艺,采用纳米级粉末材料,通过优化成形参数,成功制备了满足实际使用要求的阵列式微流道零件,成形精度误差低,不超过1.5%,降低成本50%以上。此粉末微注射成形制备阵列式微流道技术对电子机械领域微小型电子元器件的设计和制造具有重要的借鉴意义。     

TOX连接技术在板件连接中的应用

现代钣金制造业的激烈竞争和快速发展,对行业中金属板件的连接技术提出了越来越高的要求,传统的点焊、铆接作为业界常用的不可拆卸式金属板件的点连接方法,均存在着经济及技术上的不足和使用上的局限性。TOX连接是一种新的连接技术,又称为无铆钉铆接。本文主要介绍了TOX连接的原理,TOX连接与其他点连接方式相比的优越性,TOX连接采用的模具和设备及其在板件连接中的具体应用。     

An experimental work on the effect of injection molding parameters on the cavity pressure and product weight

The injection molding process is one of the most efficient processes where mass production through automation is feasible and products with complex geometry at low cost are easily attained. In this study, an experimental work is performed on the effect of injection molding parameters on the polymer pressure inside the mold cavity. Also, the effect of these parameters on the final products' weight is studied. Different process parameters of the injection molding are considered during the experimental work (packing pressure, packing time, injection pressure, injection time, and injection temperature). Two polymer materials are used during the experimental work (polystyrene (PS) and low-density polyethylene (LDPE)). The mold cavity has a cuboidal form with two different thicknesses. The cavity pressure is measured with time by using pressure Kistler sensor at different injection molding cycles. The results indicate that the cavity pressure and product weight increase with an increase in the packing pressure, packing time, and injection pressure for all the analyzed polymers. They also show that the increase of the filling time decreases the cavity pressure and decreases the product weight in case of PS and LDPE. The results show that the increase of packing pressure by 100 % increases the cavity pressure 50 % in the case of PS and 70 % in the case of LDPE. They also show that the increase of injection pressure by 60 % increases the cavity pressure 36 % in case of PS and 90 % in case of LDPE at an injection temperature of 220 °C. The results indicate that process parameters have an effect on the product weight for LDPE greater than PS. The results obtained specify well the developing of the cavity pressure inside the mold cavity during the injection molding cycles.     

仪器外壳成型新工艺-反应注射成型技术解析

反应注射成型是指针对多种有机合成的高分子材料，通过改变材料的化学结构，采用物理变化的方法（如温度、重量比例和高剪切等）来生产各种不同性能和用途的产品。反应注射成型起源于聚氨酯塑料，随着工艺技术的进步＇该工艺也扩展到了多种材料的加工中。     

改性水溶性高分子粘结剂的制备及性能的研究

动物胶粘结剂是水溶性天然高分子粘结材料,具有无毒无害、可降解等特性,但其也具有在常温下易凝聚、流动性差、型砂强度低等问题,针对这一问题需要对其进行改性处理。在碱解条件下,采用丙三醇、乙醇和糊精对动物胶进行改性处理。试验表明:在碱解过程中,水胶比为8∶5,Na OH加入量为动物胶质量的5%,在改性过程中,选择的改性剂最佳配比(质量比)为:动物胶∶丙三醇∶乙醇∶糊精=100∶10∶10∶10,改性温度为75℃、改性时间为90 min。测得其表面张力值为26.451m N/m、抗压强度达到3.30 MPa,最后通过红外光谱对改性机理进行理论分析,分析认为改性剂丙三醇、乙醇和糊精可与动物胶发生反应。结果证明丙三醇、乙醇和糊精复合改性剂可以降低动物胶表面张力,提高表面润湿性,最终使得砂型强度增大。     

Experimental investigation of the factors influencing the polymer–polymer bond strength during two-component injection moulding

Two-component injection moulding is a commercially important manufacturing process and a key technology for combining different material properties in a single plastic product. It is also one of most industrially adaptive process chain for manufacturing so-called moulded interconnect devices (MIDs). Many fascinating applications of two-component or multi-component polymer parts are restricted due to the weak interfacial adhesion of the polymers. A thorough understanding of the factors that influence the bond strength of polymers is necessary for multi-component polymer processing. This paper investigates the effects of the process conditions and geometrical factors on the bond strength of two-component polymer parts and identifies the factors which can effectively control the adhesion between two polymers. The effects of environmental conditions on the bond strength are also investigated. Investigation shows that melt and mould temperatures are vital process parameters that influence the bond strength. Besides this, surface roughness of the first-shot part and environmental factors like moisture have profound influence on the bonding of the two materials. The selections of materials and environmental conditions were done based on the suitability of MID production, but the results could be useful for two-component polymer processing for a wide range of industrial applications. The results and discussion presented in this paper are only valid for the two-component plastic parts moulded by over moulding in cavity-transfer process.     

水壶手柄注塑件的模具设计与加工

分析了某款水壶的手柄和壶口一体注塑件的外形和结构,针对加工及出模难点,合理地安排了加工工艺并设计了嵌入式顶针的模芯,该模芯兼有滑块和顶针的双重功能,很好地解决了生产中的难题。