工艺参数对注塑制品包紧力的影响及脱模力测量

注塑制品成型凝固时对型芯产生的包紧力大小及其分布,是影响制品脱模变形或开裂的主要因素。以简单矩形盒状制品为对象,设计制造了单型腔直浇口模具,并对高密度聚乙烯(HDPE)、聚丙烯(PP)及丙烯腈-丁二烯-苯乙烯共聚物(ABS)材料,进行了不同工艺参数作用下的单因素成型实验及制品脱模力的测量,研究了工艺参数变化对制品包紧力产生的作用机理及对脱模力的影响关系。结果表明,制品凝固时其内部分子的结晶、收缩及不平衡应力等,是影响制品包紧力大小的主要因素。而提高脱模温度,会使制品对型芯的包紧力明显减小,脱模力随之减小。     

基于光纤光栅传感的螺纹钻杆复合载荷多节点检测技术

引入光纤光栅应变传感器和温度传感器,结合螺纹钻杆复合载荷（轴向压力、弯矩和扭矩）分离理论,实现对钻进过程中螺纹钻杆多节点处复合载荷自动分离与在线检测,同时对钻进过程中出现的温升进行了补偿。将检测结果与电机施加的载荷（压力和扭矩）进行对比分析,认为螺纹钻杆前端（靠近钻头一侧）受到被钻物侧向挤压和摩擦阻力较大,使得电机施加的压力和扭矩传递损耗较多,导致易磨损、变形;而螺纹钻杆中段和末端只是短暂甚至未进入被钻物,传递损耗相对较少,受弯矩的影响较大。该检测技术为钻杆材料的选择、结构优化和钻进参数的选定提供技术支撑。     

非对称阿基米德螺纹的精密测量

本文导出非对称阿基米德螺纹精密跨线测量和精确公式，并给出了三种实用计算公式。其中：计算Ｍ值的公式和计算一侧最佳量针的公式较已有的公式更为简洁。文章还提出了由Ｍ值计算中径值时，用对称螺纹的公式求解的公式。     

螺纹单一中径的三针和量球法测量公式讨论

本文讨论Berndt公式[1]和苏宗康先生的公式[2]并与文章“螺纹单一中径的三针和量球法测量”[6]中的公式用计算示例进行了比较,得出相应结论：在测量大螺旋升角锯齿螺纹时Berndt公式在测试计算时有明显的误差,而苏氏公式在检验计算时有误差.     

长寿命的铸型用硅橡胶

日本信越化学工业公司最近研制成比以往的硅橡胶耐久性和脱模性好得多的真空铸型用的“KE 1360”硅橡胶,并从1989年8月中旬开始销售。用这种“KE 1360”硅橡胶制成的制品,其耐久性比用树脂和聚氨酯制造的普通制品高20～50％,抗撕裂强度也高。适于制造要求流动性、脱模性好、强度高、形状复杂、精密的真空铸模制品。同时这种硅橡胶     

非对称螺纹精密测量的误差研究

推导出非对称阿基米德螺纹精密线测量中各种微量误差对Ｍ值和ｄ２值影响的误差公式，验证了公式的正确性，并对其应用前景作了探讨。     

非对称螺纹精密测量的误差研究

推导出非对称阿基米德螺纹精密跨线测量中各种微量误差对Ｍ 值和ｄ２ 值影响的误差公式，验证了公式的正确性，并对其应用前景作了探讨     

螺纹拧紧扭矩值的计算公式

在装配过程中为了保证螺纹件的连接可靠,必须给定一个拧紧扭矩值M_(AO)在装配螺纹时使螺栓产生了一个轴向夹紧力F,轴向夹紧力F的大小与螺纹直径、螺纹螺距、螺纹材料、摩擦条件、装配零件的数量、装配方法等有关。目前我国各种手册上一般还查不到各种规格螺纹的装配力矩值。为此参考国外有关资料,根据本人实际工作经验,提出以下计算公式:     

检定扭矩扳子时应注意的问题

一、缓冲器由于动态检测时扭矩扳子的加载方式均为旋转动态加载,在实际工作中通过旋转螺母或螺栓,逐渐加大扭矩直至螺母或螺栓拧紧。因此,在检定时,如果按照常规手动扭矩扳子检测,将会与其工作状态产生很大差异,无法准确测量扭矩扳子实际输出的扭矩值。所以,必须选择一个合适的缓冲器对旋转能量进行缓冲。校准时,将扭矩扳子通过缓冲器与扭矩传感器连接,这样能较好地模拟动态扭矩扳子的实际工作状态。由于多种原因的存在,有的螺纹副需要较长的时间才能拧紧到额定扭矩值,而有的所需时间较少。根据螺纹的连接状态不相同,可分为硬连接和软连接。     

梯形螺纹跨线测量近似公式使用指南

本文用模量方法研究梯形螺纹中径公差和跨线测量近似公式时的计算误差、探讨使用近似公式时是否需要修正的一种判别方法，并给出修正量的新计算方法。     

短碳纤维增强注塑聚醚醚酮复合材料微观结构与力学性能研究

实验结果表明:短碳纤维增强注塑聚醚醚酮(CF/PEEK)注塑板材中存在"皮-芯"次层微结构,用金相显微镜可以表征CF取向度不同的皮层和芯层的厚度,整板材料的力学性能可以根据皮层及芯层的厚度及其强度按"混合规则"计算。DSC法及热烘箱法研究表明,碳纤维取向结构和PEEK在皮层和芯层中的结晶度差异导致了板材内存在较大的内应力。     

基于二次回归正交设计的啮合齿轮表面温度分析

为了缓解齿轮在啮合传动过程中齿面产生的局部高温导致齿轮表面固有熔焊粘附的问题,基于二次回归正交设计方法设计了27组因素水平试验,利用ANSYS软件对单个齿轮通过添加边界条件进行有限元分析,得到单个齿轮本体最高温度.通过Design-Expert软件对试验数据进行分析处理,得出:齿轮的转速z_1、齿轮的转矩z_2、齿轮的齿宽z_3和齿轮压力角z_4均方分别为556.82,1 813.69,278.17,20.02,即影响齿轮本体最高温度响应值的四因素主次顺序为齿轮的转矩z_2、齿轮的转速z_1、齿轮的齿宽z_3和齿轮压力角模数z_4;齿轮本体最高温度会随着齿轮的转速z_1、齿轮的转矩z_2和齿轮的齿宽z_3增大而增大;齿轮本体最高温度随着齿轮压力角z_4增大而减小.这一结论为齿轮的设计提供借鉴意义.     

羊毛角蛋白塑料的制备和力学性能

利用羊毛制备了角蛋白塑料,考察了模压压强、模压温度以及增塑剂等对角蛋白塑料力学性能的影响。结果表明,随着模压压强的增大,塑料的最大拉伸强度升高,断裂伸长率降低。模压温度对塑料的力学性能影响不大。水和甘油都是角蛋白塑料良好的增塑剂,水含量为27%和甘油含量为20%时的增塑作用最好。     

铜合金弯头冷推成形影响因素分析及工艺参数优化

基于有限元模拟软件和三维造型软件,建立有限元铜合金弯头冷推模型,进行模拟试验。结合不同的弯头冷推实际影响因素,分析了摩擦系数、模腔与芯杆间隙、推制速度对弯头冷推弯的影响。采用正交试验分析的方法建立模拟试验组,利用极差分析法分析了冷推弯中各个因素影响的主次关系,得到最优工艺参数组合。结果表明,摩擦系数为0.05,模腔与芯杆间隙为0.75 mm,推制速度为4 mm/s时,弯头冷推弯成形质量最好。实际生产验证结果与模拟结果较为吻合。     

Validation of the modified rule of mixtures using a combination of fibre orientation and fibre length measurements

The goal of this study was to investigate the fibre orientation distribution (FOD), and subsequent mechanical properties, of an injection moulded plate with two different number averaged fibre lengths, termed in this paper medium (1.35 mm) and long (2.40 mm). Fibre orientation measurements (FOD) were made using the 2D elliptical section method and an in-house developed image analyser. The samples were injected from a pin gate located at the centre and top of the plate. Expansion flow on the divergent flow front from this pin gate resulted in a core region with circumferential alignment, while through thickness shear resulted in the usual realignment of fibres in the flow direction either side of the core, termed the shell layers. Two interesting aspects were discovered from these measurements. First, and most importantly, the FOD was found to be independent of the two fibre lengths in this study, and so predominantly controlled by the mould shape and the interaction with the flow front. Second, the fibres in the core region were found to be much closer packed than those in the shell regions.The interaction between the flow front and the mould shape resulted in a range of FOD across the moulded plate, from equal in-plane orientation at the centre of the plate, to highly aligned at the plate edge. This gave a very useful set of samples from which to test out the well known modified rule of mixtures (MROM). Often the fibre orientation distribution cannot be measured directly, but indirectly using the modified rule of mixtures model in reverse. The samples from this moulding (at two different average fibre lengths) gave an excellent opportunity to validate this often used approach.Both the tensile modulus and strength (measured parallel to the injection direction) were found to show a strong correlation with the measured fibre orientation, with a significant increase in both measures between the centre and the edge of both plates. The increased length of the ‘long’ fibre plate was found to give only a small increase in tensile modulus but a much larger increase in tensile strength.The tensile modulus showed a linear dependence with the measured fourth order orientation tensor average, 〈cos⁴ θ〉, with respect to the injection direction of the plate, as predicted by the modified rule of mixtures. Excellent agreement was found between the measured modulus and the predictions from the modified rule of mixtures, based only on measured quantities (matrix modulus, fibre fraction and average fibre length) for both plates.     

一种多向侧抽芯注射模设计

为满足一种小型塑件注射成型时的多向侧抽芯要求,避免模具结构复杂化,设计了一套多向侧抽芯注射模,该模具采用一套侧抽芯装置实现了多向侧抽芯功能,借助开合模运动完成了各向侧型芯的复位、锁紧及抽芯等动作,经实践检验切实可行.     

Effects of cavity surface temperature on reinforced plastic part surface appearance in rapid heat cycle moulding

The influences of the cavity surface temperature just before filling on surface appearance and texture of the moulded reinforced plastic parts in rapid heat cycle moulding (RHCM) are investigated. Two typical reinforced plastics including ABS/PMMA/nano-C_aCO₃ and 20% fibre reinforced polypropylene (FRPP) are tested in experiments. The roughness, gloss and morphology of the part surface are characterized with white light interferometer, gloss meter, and optical microscope, respectively. It is observed that the cavity surface temperature just before filling has a significant influence on part surface appearance. With the increase of the cavity surface temperature just before filling, aesthetic quality of the moulded part can be greatly improved. There is a critical value of the cavity surface temperature just before filling for each plastic. As the cavity surface temperature reaches the critical value, part surface appearance will reach the optimal level with low roughness and high gloss. The weld mark for ABS/PMMA/nano-C_aCO₃ has a V-shaped structure while that for FRPP has a hump-shaped structure. With the increase of the cavity surface temperature just before filling, the width of the V-shaped weld mark reduces gradually until it disappears completely while the height of the hump-shaped weld mark decreases firstly and then increases. The mechanisms for the improvement of surface appearance by increasing cavity surface temperature just before filling and the generation of the V-shaped and hump-shaped weld mark are disclosed.     

Manufacturing process of reproduction plate by nonmetallic materials reclaimed from pulverized printed circuit boards

The aim of this study was to present a new method for resource utilization of nonmetallic materials reclaimed from pulverized waste printed circuit boards. A reproduction nonmetallic plate (RNMP) was prepared by adding resin paste, glass fiber and additives into nonmetallic materials using self-made hot-press former. Principle of manufacturing process and effects of mould temperature and moulding time on the mechanical properties of RNMP were studied. The results showed that when moulding pressure was fixed at 6 MPa, the optimum conditions for the RNMP were as follows: 140/135 degrees C for top/bottom mould temperature, 5 min for moulding time. The maximum content of nonmetallic materials in RNMP was up to 40 wt%. When nonmetallic material content was 20 wt%, the RNMP moulded at optimum conditions had excellent mechanical properties, with impact strength of 5.8 kJ/m(2) and flexural strength of 65.1 MPa.     

注射成型条件下尼龙1010的形态结构与性能的研究

阐述了注射成型条件下尼龙１０１０的表－芯结构，讨论了注射率和模具温度，表－芯结构，冲击强度，拉伸强度和表面硬度等力学性能的关系。     

Effect of nucleating agents and cooling rate on the microstructure and properties of a rotational moulding grade of polypropylene

Rotational moulding consists of coating the inside surface of a metal mould with a layer of plastic by rotating the mould, firstly in an oven and then in a cooling bay to induce solidification to the desired part shape. As the rotational speeds are slow (typically about 10 rev/min), the resulting hollow articles are practically stress free. The primary material used for rotationally moulded parts is polyethylene but there is an increasing interest in using polypropylene to provide stiffer, higher temperature products. Unfortunately the slow cooling combined with the slow crystallisation rate of polypropylene results in brittle mouldings with coarse spherulites. Since the inner surface of the plastic is in contact with air during moulding, degradation is also likely to occur. In order to improve the mechanical properties of the rotationally moulded polypropylene, and nucleating additives were added. The effect of using faster cooling rates was also studied. It was found that heterogeneous nucleation, both of and spherulites, did not improve the ductility of the samples. However, when fast cooling was used, the impact strength of the polypropylene improved markedly, independent of the presence of nucleating additives. In the rotationally moulded polypropylene parts, the fast cooling could only be applied to the outer surface of the mould, which led to asymmetric cooling. This resulted in severe warpage, and uneven morphology. This problem should be overcome by using fast cooling on both the inside and outside surfaces of the plastic.