粉末回转成型简介

介绍了粉末树脂回转成型的发展、原理、工艺、设备、原料及回转成型产品的特性,分析了回转成型的前景。     

回转成型用塑料及设备、工艺研究进展

综述回转成型塑料、设备与工艺的研究进展。探讨了可用于回转成型的各类塑料,尤其是聚乙烯的研究开发情况。指出必须积极开发回转成型用塑料品种,扩大原料范围,降低成本,才能加快回转成型业发展。     

滚塑成型工艺与设备发展状况

1 滚塑成型工艺及其优势 滚塑是中空塑料制品成型的一种工艺方法，又称旋转成型、旋转模塑或回转成型。滚塑过程是将塑料粉末加入模具中，然后加热模具并使之沿相互垂直的两根轴连续旋转，模具内树脂在重力和热量的作用下逐渐均匀地涂布、熔融黏附于模具内表面上，从而形成所需要的形状，然后冷却模具，脱模得到制品。     

回转钢带冷却成型机组的设计与应用

以回转钢带制片机为例,介绍了回转钢带冷却成型机组的工艺流程和常见形式,并初步估算了冷凝时间。讨论了回转钢带冷却成型机组的工艺设计与计算方法。     

炸药粉末压制工艺参数对药柱质量的影响

为了提高炸药粉末的压制成型质量,采用将炸药粉末视为连续体的建模方法,利用Shima-Oyane材料模型,以Φ26mm×22mm的JO-9159炸药药柱为例,采用高级非线性Msc.Marc建立了粉末压制过程仿真模型,分析了不同位置粉末位移及相对密度变化规律,研究了压制速率、初始密度对炸药粉末成型后相对密度及回弹量的影响。结果表明,Shima-Oyane材料模型可以较好地模拟粉末压制成型过程;炸药粉末流动的方向主要为轴向流动,与模具接触区域流动相对缓慢;压制速率以及初始密度影响炸药粉末成型后的质量,初始相对密度的提高有助于提高炸药粉末成型后的质量;压制速率在230~250mm/s时,粉末成型后相对密度较为均匀、回弹量较小,即粉末成型质量较好。     

粉末注射成型技术及其发展

从塑料加工成型的角度详细讨论了粉末注射成型的工艺过程和技术特点，该技术的关键是配制分散良好的喂料、在尽可能少用黏结剂和获得良好的熔体流动性之间达成平衡，并精确控制注射过程的温度、压力和速度。通过2个粉末注射成型实例进一步说明了粉末注射工艺控制的高要求。对粉末注射成型工艺的最新发展进行的总结表明，粉末注射成型与其他新工艺技术的结合是这一技术进一步发展的趋势。最后分析了我国粉末注射成型的现状，建议我国粉末注射成型的未来发展应该注重加强粉末冶金、高分子材料、塑料加工等多个学科研究人员的密切合作。     

陶瓷注射成型技术及其新进展

详细阐述了陶瓷注射成型技术的关键因素,全面介绍了国内外的新进展和动态,重点介绍了粉末共注成型、低压注射成型和微粉末注射成型等新技术。在此基础上评价和展望了该技术的发展前景。     

粉末注射成型技术的研究和应用

介绍了粉末注射成型技术的概念和工艺,包括金属粉末注射成型(MIM)、陶瓷粉末注射成型(CIM),讲述了黏结剂的使用发展情况;阐述了粉末注射成型专用注射成型机的特点,PIM粉末注射专用塑化系统,PIM专用料斗滑块装置,镶套式机筒座等,介绍了PIM技术在诸多行业中的应用,3C行业,医疗行业,汽车行业等,并展望了PIM研究的发展方向。     

大型异形铸型尼龙中空制品材料研究及其回转成型技术

采用双向回转成型技术,在铸型尼龙配方、成型工艺参数上进行了研究,并设计加工了成型设备,制得了大型异形中空制品。     

注塑成型新技术的发展概况

综述了近年来注塑成型技术的发展状况,介绍了新型气辅注塑成型、多组分注塑成型、粉末注塑成型、微孔发泡注塑成型、微注塑成型等技术的特点及最新动向。     

塑料滚塑制品缺陷分析及解决方案

简要介绍了旋转滚塑成型的方法和用途,指出了研究并解决滚塑制品缺陷的目的和意义。通过对滚塑制品较常见的几种缺陷的形成原因进行分析,从制品原材料、模具结构设计、滚塑成型工艺等方面提出了旋转滚塑成型的基本要求,同时提出了为获得高质量滚塑制品时应避免或减少各种缺陷的解决方案。     

滚塑发泡成型技术及其发展方向

介绍了一种新型的发泡成型技术———滚塑发泡成型技术。该技术既继承了传统滚塑成型的众多优点,同时又具有其独有的特点,即:具有发泡的芯层的同时又有光滑的表面,能大大提高产品的力学性能,弥补传统滚塑成型技术的缺点。主要从滚塑发泡成型技术的发展历程、工艺流程、加工原理、影响因素以及技术特点等几个方面,详细地介绍了如何利用滚塑发泡成型技术加工具有非发泡外壳和发泡内芯的塑料制品,并且着重介绍了一步法滚塑发泡成型工艺原理及影响因素,展望了滚塑发泡成型未来的发展方向。     

浅谈滚塑工艺在钢衬塑储罐方面的技术与应用

随着滚塑工艺的成熟发展,特别是在滚塑钢衬塑储罐以及化工防腐设备等领域的应用非常广泛,并具有强力的市场需求。这一技术的应用凸显了它的工艺结构、特点、原材料、生产设备等方面的独特优势,对产品性能、质量的稳定有了很大提高。本论文以滚塑成型工艺技术在钢衬塑产品方面的应用为分析对象,在理论与实践的基础上,对滚塑钢衬塑工艺技术、特点、原材料、成型设备、衬塑方案以及常见问题的解决方法,逐一进行了论述和总结,可为相近类型企业生产提供参考。     

滚塑工艺传热模型的研究进展

首先介绍了研究滚塑工艺传热机理的重要性,分段说明了滚塑工艺的传热过程。详细阐述了国内外在建立和发展滚塑工艺传热模型方面的研究进展。然后对现有模型进行分类和比较,并分析了造成其误差的主要原因。最后对未来的研究工作进行了展望。     

Processing enhancers for rotational molding of polyethylene

Rotational molding is a zero shear process used to manufacture hollow plastic parts. One disadvantage of this process is long cycle times, which are significantly affected by the sintering rates of thermoplastic powder. The objective of this work was to evaluate low molecular weight additives as sintering enhancers for polyethylene and to validate the results in rotational molding. The following additives were blended with linear low‐density polyethylene: mineral oil, glycerol monostearate and pentaerythritol monooleate. The additives resulted in decreased melt viscosity and/or elasticity at low shear rate. The reduction in melt elasticity was particularly significant. Sintering studies confirmed that the additives resulted in significantly faster coalescence. In uniaxial rotational molding, the decreased melt viscosity and elasticity obtained with mineral oil were observed to result in much faster densification and bubble removal. Part thickness was uniform and there was no warpage. Adding mineral oil to polyethylene reduced the cycle time in uniaxial rotational molding and the peak impact strength was identical to that obtained without any additive. Biaxial rotational molding experiments confirmed that the use of mineral oil resulted in shorter cycle time without sacrificing peak impact strength.     

单轴滚塑成型传热过程的数学建模

阐述了滚塑成型技术的基本原理、工艺特点。以单轴滚塑成型实验为依据,对工艺过程进行了适当简化和假设,着重对粉料在加热及熔融状态下的物理过程进行了分析,详细提出了单轴滚塑成型传热过程的数学模型,对模具加热时间、粉料熔融时间、熔融温度场时间函数、半径函数及温度场分布进行了求解。     

玻璃钢管的高速旋转模塑成型工艺研究

介绍了一种高速旋转模塑工艺成型纤维增强树脂基复合材料制品新技术，研究了该工艺的工艺方法及成型原理。并以成型玻璃钢管为例进行实验研究，分析了成型过程中所选转速对制品质量的影响及制品成型的时间控制问题。结果表明：该方法通过增强树脂浸润纤维的驱动力可以提高制品质量和制品的生产效率。     

Study of polyamide 12 crystallization behavior within rotational molding process

Our study is focused on the investigation of polyamide 12 (PA 12) grade behavior in rotational molding process. Hence, some rotational molding tests of polyamide 12 were conducted on a STP LAB 40 machine. To simulate the cooling stage within the rotational molding, the crystallization behavior of polyamide 12 was studied using differential scanning calorimetry technique and the obtained results for non-isothermal crystallization were fitted with Ozawa model. Furthermore, morphology survey has been carried out by a hot stage method using a microscope to investigate the spherulites evolution which depends on the temperature. The micro-tensile properties have been studied using micro-tensile bench (MVTV2) to explain the mechanical behavior of polyamide 12 during crystallization. As a result, the rotational molding of PA 12 was successfully carried out. The simulation of the melting and crystallization stages, by application of Ozawa model coupled with enthalpy method gave a good representation of experimental data on one hand. On the other hand, all characterization revealed useful information to understand the different phenomena that govern the rotational molding process.     

Bubble removal in rotational molding

Closed form solutions have been obtained for bubble dissolution in typical polymer melts encountered in rotational molding. The solutions are in excellent agreement with experimental data available in the literature. Using these solutions, it is shown that under typical rotational molding conditions the polymer melts may be almost saturated. As a result, bubble shrinkage occurs over long periods. Depending on the degree of saturation, surface tension may contribute substantially to the concentration gradient that drives bubble shrinkage. It is also shown that a pressure increase imposed on a nearly saturated polymer melt leads to a steep concentration gradient at the bubble/melt interface that can cause extremely fast bubble shrinkage. Applied to the rotational molding process, such a pressure increase can result in substantial cycle‐time shortening through elimination (or reduction) of the currently used excessive heating. A further benefit may be that additional resins, which at present cannot be used because of oxidation at sustained high‐temperatures, can become available to the rotational molding industry. Under the under‐saturated conditions created by a pressure increase, the effect of surface tension on the rate of bubble shrinkage is negligible.