共查询到19条相似文献,搜索用时 109 毫秒
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介绍了注塑件熔接痕的形成机理,分析了影响熔接痕强度的各种因素,从注塑工艺参数设定、模具结构设计等方面给出了消除熔接痕或提高熔接痕强度的措施。 相似文献
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论述了熔接痕的形成原因,分析了熔接痕的微观结构,介绍了通过改善加工方法增强熔接痕强度的措施,指出了增强熔接痕强度研究的开发方向、技术动态和发展趋势。 相似文献
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材料流变性能对注塑制品熔接痕的影响 总被引:4,自引:1,他引:3
介绍注塑制品熔接痕的分类及其形成,分析材料的流变性能对注塑制品熔接痕外观及性能的影响,着重阐述通过调整注塑工艺参数以改变材料的流变性能,从而改善熔接痕对注塑制品外观及性能的影响,并综合提出减小熔接痕损害的措施与方法。 相似文献
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介绍了影响熔接痕的各种因素,借助Moldflow模拟分析软件对插座上盖注塑成型进行了模拟,根据结果分析了熔接痕并,优化了模具的浇口位置最,终使熔接痕数量减少且处于不重要的部位。 相似文献
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简要介绍了注射成型中熔接痕的影响因素和控制方法,从熔接痕控制方法和聚光片的结构入手,利用Moldnow软件对塑料件进行成型模拟,分析在试模过程中塑料件表面出现熔接痕的原因,通过改变浇口的位置和结构,并进行相应模拟分析,成功解决了聚光片熔接痕缺陷问题,达到了设计要求. 相似文献
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基于数值模拟的汽车外饰件熔接痕分析及其优化设计 总被引:1,自引:0,他引:1
单志;梅益;郭建兵;李阳俊;秦舒浩 《中国塑料》2010,24(4):58-60
采用Moldflow软件对汽车外饰件的熔接痕进行分析,并基于该软件的二次开发原理对熔接痕结果进行量化输出,以量化后的结果作为评价指标,结合正交设计获得了1组最优工艺参数及各工艺参数对熔接痕的影响规律;最后,应用Moldflow软件对最优工艺参数进行验证。 相似文献
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K. Tomari S. Tonogai T. Harada H. Hamada K. Lee T. Morii Z. Maekawa 《Polymer Engineering and Science》1990,30(15):931-936
A major factor that weakens the weld line in injection moldings is the V-notch structure. Though the existence of a V-notch is well known, its depth variation with molding conditions has not been detailed. The aim of this paper is to clarify the V-notch structure and its effect on the strength of general purpose polystyrene injection moldings. A dog bone type tensile specimen with a weld line was molded under several molding conditions. The surface of the weld line was partially eliminated by cutting with a milling machine to seven levels of cut depth (Dc). As a result, the weld strength increased with Dc to about 50%. The relationship between the weld strength and Dc made it possible to determine the V-notch depth, which vas defined as the “depth of the weld line.” From these results, a hypothesis is proposed that the V-notch has a structure with a fine groove on the surface and a poorly bonded inner layer. This study considered the relationships among the weld strength, the depth of the weld line, and molding conditions. 相似文献
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从熔接痕的成型机理出发,考虑了困气状况和熔合温度对熔接痕熔合质量的影响,提出一种以困气改善辅助提升熔接痕熔合质量的方法,建立了以“气穴面积”和“熔接痕处流动前沿温度”为熔接痕熔合质量指标的多目标评价体系,并构建了一种基于Kriging模型和非支配排序遗传算法(NSGA-Ⅱ)的多目标寻优策略,以实现工艺参数的择优选择。以多孔板熔接痕优化为例,选用拉丁超立方抽样(LHS)设计实验,建立并检验反映工艺参数和优化目标之间影响规律的Kriging模型,采用NSGA-Ⅱ确定多目标优化问题的Pareto前沿及其最优解。仿真及生产实验结果表明所建立的多目标优化策略能有效实现熔接痕的多目标优化,同时以困气改善辅助提升熔接痕熔合质量的方法效果显著。 相似文献
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Luís L. Ferrás Yalew Sitotaw Célio Fernandes João M. Nóbrega Olga S. Carneiro 《Polymer Engineering and Science》2018,58(3):249-260
In this work, we present a study on numerical and experimental approaches aiming to improve our understanding about the relation between the flow conditions and the strength of weld lines in extruded profiles. For this purpose, a prototype extrusion die that comprises a movable spider leg is used to produce tapes under different flow conditions, by varying the location of the spider leg and the flow rate. The same case studies are numerically studied, considering a viscoelastic Giesekus constitutive model. The numerical results are then investigated to identify potential relationships between the flow conditions, in which the weld lines are formed, with the strength of the weld line experimentally characterized. The results obtained allow identifying a clear correlation between the flow conditions and the weld‐line strength. POLYM. ENG. SCI., 58:249–260, 2018. © 2017 Society of Plastics Engineers 相似文献
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In this work, the mechanical strength and weld line morphology of injection molded polystyrene/poly(methyl methacrylate) (PS/PMMA) blends were investigated by scanning electron microscopy (SEM) and mechanical property test. The experimental results show that the tensile strength of PS/PMMA blends get greatly decreased due to the presence of the weld line. Although the tensile strength without the weld line of PS/PMMA (70/30) is much higher than that of the PS/PMMA (30/70) blend, their tensile strength with weld line shows reversed change. The viscosity ratio of dispersed phase over matrix is a very important parameter for control of weld‐line morphology of the immiscible polymer blend. In PS/PMMA (70/30) blend, the PMMA dispersed domains at the core of the weld line are spherically shaped, which is the same as bulk. While in the PS/PMMA (30/70) blend, the viscosity of the dispersed PS phase is lower than that of the PMMA matrix, the PS phase is absent at the weld line, and PS particles are highly oriented parallel to the weld line, which is a stress concentrator. This is why weld line strength of PS/PMMA (30/70) is lower than that of PS/PMMA (70/30) blend. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1856–1865, 2002; DOI 10.1002/app.10450 相似文献
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In many injection molded parts weld lines are often unavoidable. These cause optical defects and a reduction of the mechanical properties of the part. Therefore, the predictability of the weld line strength at an early stage of development would provide a significant advantage by avoiding costly iterations of the mold and increases the understanding of the correlation between process history of the melt and weld line strength. For this purpose, a calculation routine has been developed to predict the weld line strength based on injection molding simulation. Different models to calculate the healing of a weld line are compared and analyzed. By adding a factor to consider the shear rate in addition to the temperature and the pressure and after calibration to one design of experiment setting of the experimental data, the prediction of the weld line strength shows good agreement for all examined process setpoints of the experimental data for polystyrene. 相似文献
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Yutaka Kobayashi Gensei Teramoto Toshitaka Kanai 《Polymer Engineering and Science》2011,51(3):526-531
In this article, a weld line placed behind an obstacle in an injection‐molded plaque made of metallic mold‐in‐color polypropylene (PP) was investigated. A broad uneven glossy section was visually observed along the weld line after the v‐notch weld disappeared. Although disk‐shaped metallic pigments were oriented parallel to the wall according to laminar flow, the pigment particles at the weld behind the obstacle were ordered vertically at the center of the depth direction. In PP molded without pigment, a black line was observed at the same position in the metallic weld. Based on a measurement of the crystal structure, the black line was caused by the rapid cooling of molten PP. Elongational flow occurred along the weld line after the diminishing v‐notch weld. The unique flow ordered the pigments obliquely at the advancing flow front and disturbed the subsequent flow of hot PP which transferred heat to the crystallizing mass. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers 相似文献
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《Ceramics International》2023,49(20):32440-32447
The crack of ceramic weld is a worldwide problem for brittle material, high energy laser beam is expected to solve this problem. In this paper, the crack of fiber laser welding of Al2O3 ceramics was studied. The weld crack rate was used to characterize the crack condition of weld, and the influences of laser power, welding speed and defocusing distance on crack characteristics were carried out. The results showed that Al2O3 ceramics weld has obvious crack tendency, and the cracks mainly appeared on the weld center line. When the crack appeared on the weld center line, there was crack-free on the base metal. When the defocusing distance increased from +3 mm to +20 mm, the number of cracks gradually decreased. When the defocusing distance was greater than +17 mm, cracks-free appeared on the weld and base metal. Abaqus software was used to simulate the relationship between crack and stress based on thermal elastoplastic theory. The high crack areas, few crack areas and free crack areas were divided according to the maximum principal stress value. No matter what welding conditions, as long as the maximum principal stress was less than 1576 MPa, there was crack-free on the weld and base metal. 相似文献