纸浆模塑成型工艺及模具结构优化设计

发布时间：2018-11-26 09:19

【摘要】：纸浆模塑制品主要应用于产品的缓冲包装,它以纸纤维为原材料,具有低成本、容易降解、透气性好等优点。纸浆模塑制品是一种环保包装材料,在生产和使用过程对环境不造成污染。但目前国内纸浆模塑制品生产技术比较落后,特别是制品生产成本高,合格率低等问题限制了纸浆模塑工业制品的发展。本文对现有纸浆模塑成型机的生产工艺进行优化,为实现其工艺优化,重点对吸滤成型模具的吸浆孔结构、模具背腔结构、热压模具的加热板孔道结构以及对吸滤成型模具支架结构进行了优化设计,从而提高制品生产效率及质量,降低生产成本的目的。首先,在吸滤工艺阶段,为缩短模具吸浆时间,提高吸滤成型效率及吸浆均匀性,对纸浆模塑吸滤成型模具的吸浆孔参数进行优化。文章先通过理论分析得出模具吸浆孔的孔径大小及入出口截面突变是影响吸浆过程压力损失的因素,并利用ANSYS/FLOTRAN仿真分析软件分别对不同孔径、不同锥度、不同倒角半径的模具吸浆孔模型进行模拟分析,对比分析得到最优吸浆孔结构参数。其次,为使制品脱模压力更均匀,对吸滤成型模具的脱模工艺进行了研究。首先建立了模具背腔流场的CFD三维数值模型,并对气流分布板不同的开孔率、不同布置位置进行了数值模拟分析,通过对比分析得到了气流分布板的最佳开孔率及安装位置;在确定气流分布板的结构及位置的基础上,对背腔截面突变位置进一步优化,可减小气流的局部能量损失,优化后提高了出口截面的气流平均速度,进一步提高了产品脱模效率。同时,在热压成型工艺阶段,为提高加热板热传递效率及制品质量,缩短制品热压成型时间,采用ANSYS软件的热分析模块对纸浆模塑热压成型模具的加热板进行了研究,即对原加热板的孔道结构进行优化,得到加热板工作面温度分布更均匀的优化方案。再次,利用有限元分析软件ANSYS的Design Opt模块,对纸浆模塑成型设备吸滤成型模具支架进行了减量化、轻量化设计。原吸浆模支架空间布局不紧凑,限制了吸滤模具浸入浆液的深度且强度有较大富裕,存在优化空间。经过优化得到了纸浆模塑吸浆模支架结构轻量化的优化设计方案,减少了支架体积及总质量,节约了生产成本。最后,对优化后得到的模具吸浆孔最优结构参数及热压模具加热板进行改进并进行实验验证,测试结果表明,制品的成型效率及质量都有所提高,优化效果显著。
[Abstract]:Pulp molded products are mainly used in cushioning packaging of products. Paper fibers are used as raw materials, which have the advantages of low cost, easy degradation, good permeability and so on. Pulp molded product is an environmental-friendly packaging material, which does not pollute the environment in the process of production and use. However, the production technology of pulp molded products in China is relatively backward at present, especially the problems of high production cost and low qualified rate limit the development of pulp molded products. In this paper, the production technology of the existing pulp molding machine is optimized. In order to realize the process optimization, the structure of the suction hole and the back cavity of the mould are emphasized. The orifice structure of hot pressing die heating plate and the structure of suction molding die bracket were optimized in order to improve the production efficiency and quality of the products and reduce the production cost. Firstly, in order to shorten the suction time, improve the efficiency and homogeneity of the suction molding, the parameters of the pulp mold were optimized. Through theoretical analysis, it is concluded that the pore size of the suction hole and the sudden change of the inlet and outlet cross section are the factors that affect the pressure loss during the pulp suction process, and the different apertures and different taper are obtained by using the ANSYS/FLOTRAN simulation analysis software. The model of die suction hole with different chamfer radius was simulated and analyzed, and the optimum structure parameters of suction hole were obtained by comparison and analysis. Secondly, in order to make the product demoulding pressure more uniform, the mold removal process of the suction molding die was studied. Firstly, the CFD three-dimensional numerical model of the flow field in the back cavity of the die is established, and the numerical simulation analysis of the different orifice rate and the different arrangement position of the airflow distribution plate is carried out. The optimum opening rate and the installation position of the airflow distribution plate are obtained by comparison and analysis. On the basis of determining the structure and position of the airflow distribution plate, the catastrophe position of the back cavity section is further optimized, which can reduce the local energy loss of the airflow, and increase the average velocity of the airflow at the exit section after the optimization. Further improve the efficiency of product demoulding. At the same time, in order to improve the heat transfer efficiency and product quality of the heating plate and shorten the forming time of the product, the heat analysis module of the ANSYS software was used to study the heating plate of the pulp molding hot pressing mould. In other words, the hole structure of the original heating plate is optimized, and a more uniform temperature distribution scheme of the heating plate working face is obtained. Thirdly, using the Design Opt module of the finite element analysis software ANSYS, the mold support of the pulp molding equipment is reduced and light weight is designed. The space layout of the original suction die support is not compact, which limits the depth of the suction die immersion into the slurry, and the strength is relatively rich, and there is an optimization space. Through optimization, the optimum design scheme of light weight structure of pulp moulding suction mould support structure is obtained, which reduces the volume and total quality of the support and saves the production cost. Finally, the optimized structure parameters of the suction hole and the heating plate of the hot pressing die are improved and verified. The test results show that the molding efficiency and quality of the products are improved, and the optimization effect is remarkable.
【学位授予单位】：湖南工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TB484

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