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一、气辅成型概述
将气体作为工作介质应用到高分子材料加工技术中来,最先是在注射成型中应用,所以这项技术通常被称作气体辅助注射成型技术。 相似文献
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《实验室研究与探索》2016,(1):43-46
为实现注射成型制品的微观结构调控,在气体辅助注射成型等方法的基础上,设计并实现了高分子材料多熔体多次注射成型的新型加工技术,即对两种聚合物组分,其中一种欠料注射进入模具型腔后,另一种熔体对基体聚合物熔体快速穿透,并推动外层熔体充填满整个型腔。初步探索了多熔体多次注射成型的剪切场分布与结晶性高分子制品的多层次晶体形态。研究发现:与传统注射成型过程不同,多熔体多次注射成型过程由于引入了二次熔体穿透的过程,流场特性情况比传统注射成型更为复杂,剪切速率沿制品厚度方向的分布表现出双峰分布特征。聚合物在多熔体多次注射成型过程中,受到刚性模壁和柔性熔体的双重界面约束,导致制品的形态结构的形成与演变更为复杂。在多熔体多次注射成型制品的次表层和芯层区域有柱晶结构形成,其制品表现出特殊的双"皮-芯"结构。 相似文献
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杨丁 《四川职业技术学院学报》2008,18(1):118-119
介绍气体辅助注射成型的原理,并用Moldflow软件对具体制品做了CAE分析。介绍在Moldflow中实现气辅分析的步骤,并对分析结果在实际工作中的指导意义作了阐述。 相似文献
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磁性材料的注射成型技术 总被引：1，自引：0，他引：1
高广进 《天津职业院校联合学报》2002,4(3):103-104
研究成型工艺时,从阐述磁性材料注射成型的原理,介绍了磁性材料粘合剂、磁性材料颗粒和其注射模具、注射工艺的特点。并且在磁性颗粒塑料粘结剂、模具、工艺等方面分析了该工艺的关键技术。 相似文献
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注射成型制品的表观缺陷及其预防措施 总被引：2，自引：0，他引：2
杨太德 《连云港职业大学学报》1998,11(1):39-41
随着塑料工业的迅速发展,注射成型制品已经被广泛用做工业产品的结构零部件或装饰零件,因此它们的表面质量也就显得越来越重要。在制品的表面质量中,表观成型缺陷不仅影响制品外表的美观,而且往往也是注射成型工艺条件、模具条件和成型物料选择不当的反映,或是制品内部质量不良的外部表征。因此,研究成型缺陷的生成原因及其预防措施,对于注射成型的很重要的意义。制品表观缺陷的种类较多,但归纳起来有以下几个主要方面。 相似文献
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利用CAE模拟分析软件对手机下盖进行注射成型过程动态模拟,预测可能发生的缺陷,并针对缺陷情况提出优化方案,对注射成型工艺、产品壁厚设计和模具浇注系统进行优化,最终获得手机下盖注塑成型的最佳方案。 相似文献
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杨太德 《连云港职业技术学院学报》1998,(1)
随着塑料工业的迅速发展,注射成型制品已经被广泛用做工业产品的结构零部件或装饰零件,因此它们的表面质量也就显得越来越重要。在制品的表面质量中,表现成型缺陷不仅影响制品外表的美观,而且往往也是注射成型工艺条件、模具条件和成型物料选择不当的反映,或者是制品内部质量不良的外部表征。因此,研究成型缺陷的生成原因及其预防措施,对于注射成型有很重要的意义。 制品表观缺陷的种类较多,但归纳起来有以下几个主要方面。 相似文献
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注射成型收缩与模具尺寸 总被引：1，自引：0，他引：1
从塑料材料特性、注射成型工艺条件、塑件形状、模具结构等方面，揭示了注射成型收缩对塑件尺寸精度的影响因素，介绍了减小塑件成型收缩的方法，在文献研究的基础上，提出了一种由实践探索得出的可降低收缩率计算误差的型芯、型腔计算公式。 相似文献
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Souvik Ghosh H.N. Verma Dinesh Chandra P. Nanda 《The Journal of Agricultural Education and Extension》2013,19(1-4):17-26
The key to agricultural development in the eastern region of India, where problems of excess water and water scarcity coexist, is the scientific management of water resources with the adoption of recommended water-management technologies. A vast networking of infrastructure for the development and dissemination of water- management technologies have been designed since the very inception of planned economic change. Despite these concerted efforts, a large number of recommended technologies are either being adopted in piece-meal or not at all. The research and extension systems have been generating and disseminating technologies, therefore, it was felt worthwhile to assess the feasibility and appropriateness of recommended tecnologies as perceived in the first instance by the personnel of the research system and followed by the extension personnel. These steps were felt to be a precursor to screen the recommended technologies for their dissemination and evaluation in different farming systems. The assessment of recommended water-management technologies was performed after their documentation from different organisations working in the field of water management in two eastern India states viz. Orissa and West Bengal. The perception of 30 personnel members of the research system regarding the feasibility of these technologies elucidated that out of 86 documented recommended water-management technologies, 40 were having feasibility scores of ≥ 4.0; 8 technologies with score £ 3.0 and the rest of the 38 technologies with a score between 3.0 and 4.0 on a feasibility continuum range from 1.0 (not feasible) to 5.0 (highly feasible). Out of 40 recommended technologies (already assessed as highly feasible by the research personnel), extension personnel have perceived 16 and 10 technologies as highly appropriate and feasible, respectively. While six and four technologies were found to be less appropriate and feasible, respectively. Correlation of all nine indicators of appropriateness with feasibility of technologies was significant. Five indicators of appropriateness viz. simplicity, physical compatibility, production sustainability, cultural compatibility and cost together constituted 36.8 per cent of the total variation in feasibility with the ‘t’ values and ‘F’ values being significant. It indicates that not appropriateness of technologies alone but other factors influence the feasibility of technologies. 相似文献
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Julie A. Furst-Bowe 《Performance Improvement Quarterly》1996,9(4):57-78
The purpose of this study was to describe computer-based technologies and distance learning systems currently used in employee training and to determine which technologies will be used in future training processes. The competencies needed by trainers to use the various types of technologies were also examined, including preferred sources of competency development. Barriers trainers face when implementing new technologies were also determined. A questionnaire was developed and used to collect the data from 381 ISPI members. The results indicate that organizations are using a wide range of technologies in training, and that the major types of technologies will not change significantly in the next three years. However, there are several newer, more sophisticated technologies that will be used with greater frequency in the future. The respondents indicated that it was more important for trainers to be able to use or assist trainees in the use of a system than to be able to develop new systems or programs. Vendor training and self-study methods were identified as the two most common resources for developing competencies in instructional technology. 相似文献
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Chris Shelton 《British journal of educational technology : journal of the Council for Educational Technology》2014,45(4):748-759
Although there have been many claims that technology might enhance university teaching, there are wide variations in how technology is actually used by lecturers. This paper presents a survey of 795 university lecturers’ perceptions of the use of technology in their teaching, showing how their responses were patterned by institutional and subject differences. There were positive attitudes towards technology across institutions and subjects but also large variations between different technologies. Two groups of technology were identified—“core” technologies, such as Powerpoint, that were used frequently, even when lecturers felt that they were not having a positive impact on learning, and “marginal” technologies, such as blogs, that were used much less frequently and only where they fitted the pedagogic approach or context. Rather than there being “leading” universities that were the highest users of all technologies, institutions tended to be heavier users of some technologies than others. Similarly, subjects could be associated with particular technologies rather than being consistent users of technology in general. The study suggests that university technology policy should reflect different disciplines and contexts rather than “one size fits all” directives. 相似文献
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钛酸系铁电薄膜是铁电薄膜中最重要的一类,其制备技术繁多.虽然很多文献对各种制备技术的优缺点有所论述,对于其适用性则未有全面的分析.本文结合钛酸系铁电薄膜的化学成分特点,对主要的铁电薄膜制备技术进行分类,通过比较分析各种技术的特点,讨论这些技术在实验室基础研究、商业化生产、军工或高附加值产品制备这三方面的适用性,可为铁电薄膜制备技术研究人员在技术选用、方向把握方面提供参考. 相似文献
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Michael Flavin 《Interactive Learning Environments》2016,24(7):1665-1673
This paper examines the usage of institutional and non-institutional technologies to support learning and teaching in UK higher education. Previous work on disruptive technology and disruptive innovation has argued that users prefer simple and convenient technologies, and often repurpose technologies from designers' intentions; this paper evaluates its data in relation to this argument. The paper uses a structured observation as its research instrument; seven participants (three lecturers and four students) were given one of two tasks. Results showed the participants using a narrow range of technologies, and showed a preference for non-institutional over institutional technologies. The paper argues that there is a misalignment between the technologies provided by higher education institutions (HEIs) and the technologies used in practice by students and lecturers, and further argues that disruptive technology and disruptive innovation comprise a useful means of assessing the likely success, in terms of usage, of a technology. 相似文献
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按开放式系统互连参考模型层次的顺序,从下至上地介绍了各层对移动性支持的研究进展,总结其优势和不足,指出切换设计和服务质量保证决定移动互联网的成败,而重叠覆盖网络优化、基于效用模型的服务质量保证技术对移动互联网接入质量至关重要。最终说明容断网络、云平台和数据融合技术的结合可实现以较小代价获得较好的移动互联网质量。 相似文献
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The purpose of this study was to investigate teachers’ beliefs regarding the integration of technologies from the 2011 K-12 edition of the Horizon Report into their local, public school contexts. Teachers read the Horizon Report and then participated in an asynchronous, threaded discussion focusing on technologies they would like to see integrated into their classrooms and technologies they do not see possible in the near term. Qualitative methods were used to analyze the discussion. Findings include the teachers’ desire to see mobile technologies integrated into their classrooms, and their belief that there are significant barriers to game-based learning. 相似文献
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Chris Shelton 《Technology, Pedagogy and Education》2017,26(3):303-321
University lecturers use a wide range of technologies when teaching and there has been much research into how particular technologies are adopted. However, there are also many technologies that, despite early promise, are no longer being used in university teaching and have been abandoned by institutions or individuals. This article presents the results of a qualitative investigation into why university lecturers stop using technology. It used detailed episodic narrative interviews to explore the experiences of lecturers using technology in their teaching at three UK universities. While the data provides examples of technologies that were discarded as they became outdated and were replaced by new devices, this was not the only reason that technologies are rejected. The data also demonstrated that even relatively up-to-date or innovative technologies or practices (e.g. the use of Facebook) may be abandoned. The article discusses the participants’ experiences of ceasing to use technology and demonstrates the importance of context in decisions about using technology and social media in teaching. The article argues that studies of technology adoption should be accompanied by research that revisits the sites of these studies to consider how the implementation of technology continues over time and how it comes to an end. 相似文献
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潘旭 《闽西职业技术学院学报》2014,(3):115-120
从现有各种网络存储技术的基本原理出发,分析了每一种网络存储技术的优点和存在的问题,围绕目前的几种主流网络存储技术进行了讨论。结合大数据的基本概念进行剖析,并对大数据的主要应用和网络存储作简单对比。最后归纳总结大数据时代所面临数据存储的新挑战。 相似文献