节点文献
热流道热平衡及测控系统的应用研究
The Research on Application of Thermal Balance and Temperature Control for Hot Runner System
【作者】 李传戈;
【导师】 龚邦明;
【作者基本信息】 西南交通大学 , 机械制造及自动化, 2008, 硕士
【摘要】 热流道可看作是注射成型机的延伸,是注塑模结构的一部分。它连接注塑机喷嘴和模具型腔,把注塑机射出的熔融塑料输送到型腔内部。和传统的冷流道不同,它具有自己的加热系统或采用绝热方式,从而保持流道内的塑料在成型期间始终处于熔融状态。在模具开模时,流道内的塑料熔体不需要固化为废料取出,而滞留在流道内的熔体可以在下一次注射时注入模具型腔,提高了材料利用率。热流道技术是注射成型工艺技术上的一次革命,是注射成型技术的一个重要发展方向。热流道模塑作为注塑模具工业发展的一项前沿技术,目前主要由少数欧美著名热流道公司研制开发和商业化应用。这一技术在国内尚处于逐步推广阶段,前景很好,潜在市场很大,热流道技术的开发应用势在必行。开展对热流道技术相关理论和设计要点的探索,无疑有助于热流道技术在国内的普及应用和更快的发展,以缩短同国外先进热流道技术水平的差距。保证热流道系统的热平衡状态是热流道的关键技术之一。系统的理想状态是保持给定的温度,使塑料熔体控制在恒定状态。加热器能均匀加热,补偿热量的损失。本文在参阅大量国内外资料的基础上,分析了影响热流道热损失的各因素,并计算加热元件所需的功率。根据传热学原理,建立了热流道热平衡的数学模型。同时利用ANSYS进行热分析,优化加热元件的布局,以保证热流道加热的均匀性。开发了基于PID控制的单片机测控系统,利用灵敏的热电偶,对热流道系统的流道板和各喷嘴进行精确的温度控制。
【Abstract】 As components in injection mould, Hot runner system can be seen as an extention of injection molding machine. The purpose of an hot runner system is to feeds plasticised material into the cavity of the mould in a similar state to that in which it left the injection moulding machine nozzle. Different from the traditional cold runner gating system, hot runners has its own heating system or insulation to hold the the melt state during the processing. When open the mold, sprue removal needn’t take out, and can be used in the next cycle time, so raised material utilization ratio. Hot runner technology is a revolution and an important direction of development in injection moulding and processing.As an advanced technology in injection molding industry, hot runner technology is developed and commercial applied by small number of well-known European and American companies, however the application of this technology is still at the stage of gradual promotion in our country. With great prospects and market potential, the development and application of hot runner technology is imperative. It is no doubt that the theory study of hot runner technology will improve far-ranging application and fast development, so as to fill the gap with the advanced country.One of the key points is to hold the hot runner system in a state of thermal equilibrium,which means that heat losses must be compensated for by heating. In the ideal case, an hot runner system will be in an isothermal state.Reference to a large number of information at home and abroad , the paper analyzed the power consumption and how to calculate the power demand. According to the principles of heat transfer, mathematical model of thermal equilibrium is established, and ANSYS software is to be used for the optimal layout of the heating element. According to the MCU regulator with PID control algorithms and sensitive thermocouples, the precision temperature control can be attained.
【Key words】 hot runner; thermal equilibrium; PID; MCU; temperature control;