集成生命周期环境影响评估的塑料管材挤出模具轻量化设计方法

发布时间：2018-06-23 21:08

本文选题：挤出模具 + 轻量化设计　；参考：《重庆大学》2016年硕士论文

【摘要】：随着工业的发展,挤出模具已广泛应用于塑料管材的生产制造。塑料管材挤出模具通常依据设计者的经验设计,为了保证挤出模具具有足够的强度和刚度,往往会在一定程度上增加挤出模具的尺寸,这种不合理的设计方式会导致挤出模具质量过重,造成原材料的浪费。轻量化设计方法是在保证设计产品强度和刚度的情况下减少产品的重量,通过减少原材料的使用来减少对环境造成的影响。然而,轻量化设计之后的产品从全生命周期角度并不总是能够减少产品的环境影响。轻量化在设计阶段对产品结构、材料等的优化,有可能会影响产品在生命周期其它阶段的环境影响,不合理的轻量化设计方法甚至会增加产品全生命周期阶段的环境负荷。而现有的轻量化设计方法仅仅考虑以产品重量为目标,并没有考虑轻量化设计对产品全生命周期内环境的影响。因此,本文针对塑料管材挤出模具提出了一种集成生命周期环境影响评估的轻量化设计方法,用于减少塑料管材挤出模具的重量,同时优化挤出模具生命周期内的环境性能。首先,分析了塑料管材挤出模具的特点,阐述了现有挤出模具及轻量化设计存在的问题。在此基础上,提出了一种面向塑料管材挤出模具轻量化设计方法的框架。该框架集成了生命周期环境影响评估和结构优化方法,以塑料管材挤出模具的重量和挤出模具生命周期内的环境影响为目标函数进行结构优化,选取挤出模具各个零件的形状参数为设计变量,以挤出模具结构的强度和刚度为约束条件。其次,进一步对塑料管材挤出模具结构优化过程中目标函数和约束条件的获取进行研究。为了获得挤出模具的强度和刚度的约束条件,基于有限元法和流体力学原理对熔融塑料进行流体仿真,对塑料管材挤出模具进行热力耦合分析。为了获得挤出模具环境影响的目标函数,基于生命周期评估的原理和方法,评估塑料管材挤出模具生命周期内的环境影响。最后,基于上述的研究,选取塑料管材挤出模具不同零件的形状参数作为设计变量,结合结构优化方法,建立挤出模具轻量化设计的数学模型,并将本文的轻量化设计方法应用于一种塑料管材挤出模具。对比分析原始模型、现有的轻量化设计方法以及本文所提出的轻量化设计方法获得的挤出模具生命周期内的环境影响,验证本文提出的轻量化设计方法的有效性。
[Abstract]:With the development of industry, extrusion die has been widely used in the production and manufacture of plastic pipes. The plastic tube extrusion die is usually designed according to the designer's experience. In order to ensure that the extrusion die has sufficient strength and rigidity, the size of the extrusion die is often increased to a certain extent. This unreasonable design method will lead to excessive quality of extrusion die, resulting in waste of raw materials. The method of lightweight design is to reduce the weight of the product while ensuring the strength and rigidity of the design product, and to reduce the impact on the environment by reducing the use of raw materials. However, the product after lightweight design does not always reduce the environmental impact of the product from a life-cycle perspective. The optimization of the product structure and materials in the design stage may affect the environmental impact of the product in other stages of the life cycle. The unreasonable lightweight design method may even increase the environmental load in the whole life cycle of the product. However, the existing lightweight design methods only consider the product weight as the target, and do not consider the impact of lightweight design on the environment throughout the product life cycle. Therefore, this paper presents a lightweight design method for plastic tube extrusion die, which integrates environmental impact assessment of life cycle, which is used to reduce the weight of plastic tube extrusion die and optimize the environmental performance during the life cycle of the extrusion die. Firstly, the characteristics of plastic tube extrusion die are analyzed, and the existing problems in extrusion die and lightweight design are expounded. On this basis, a framework of lightweight design method for plastic tube extrusion die is proposed. The framework integrates life cycle environmental impact assessment and structural optimization methods, and takes the weight of plastic tube extrusion die and the environmental impact during the life cycle of extrusion die as objective functions for structural optimization. The shape parameters of each part of the extrusion die are selected as design variables, and the strength and stiffness of the extrusion die structure are taken as the constraint conditions. Secondly, the acquisition of objective function and constraint conditions in the process of optimization of plastic tube extrusion die structure is further studied. In order to obtain the constraint conditions of the strength and stiffness of the extrusion die, the fluid simulation of the melt plastic was carried out based on the finite element method and the principle of fluid mechanics, and the thermo-mechanical coupling analysis of the extrusion die for the plastic pipe was carried out. In order to obtain the objective function of environmental impact of extrusion die, based on the principle and method of life cycle assessment, the environmental impact of extrusion die life cycle of plastic pipe was evaluated. Finally, based on the above research, the shape parameters of different parts of extrusion die of plastic pipe are selected as design variables, and the mathematical model of lightweight design of extrusion die is established by combining the structural optimization method. The lightweight design method is applied to a plastic tube extrusion die. Compared with the original model, the existing lightweight design methods and the environmental impact in the life cycle of the extrusion die obtained by the lightweight design method proposed in this paper, the effectiveness of the proposed lightweight design method is verified.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TQ320.724

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