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在大中型塑料注射模具(简称塑料模具)设计中通常以刚度计算作为确定型腔壁厚尺寸的依据。本文提出以强度计算为依据,采用设置预应力件的方法提高型腔壁刚性,达到同样效果。文中就两种设计方法进行了比较,后者节约型腔壁材料30％～50％,成本大大降低。深圳亿华机械工业有限公司(以下简称亿华公司)的实践证明,是行之有效的。随着电视机、收录机等家电产品的普及应用,对于大中型塑料注射成型制品提出了更大数量和更高质量的要求。这种模具在注射成形过程中,型腔侧壁承受着较大的塑料流动压力和浇口封闭前一瞬间的保压应力,引起型腔侧壁的变形。此变形如果超越了一定限度,充模的物料增多,不仅造成溢料,而且在物料冷却收缩时,随着型腔压力的下降,侧壁变形要弹性回复,当回复量超过塑料冷却收缩量时,塑料制品的周边被嵌在型腔内难以脱模,损坏塑料件,严重时将损坏模具。因此,在大中型塑料模具设计中,型腔侧壁的刚性问题非常重要。本文从塑料模具设计中强度和刚度计算问题入手,进行了理论分析和经济性比较,提出了新的设计方法,并作了试验。下面分几个方面讨论。
In large and medium-sized plastic injection mold (referred to as plastic mold) design is usually calculated as the stiffness of cavity wall thickness to determine the size basis. In this paper, based on the strength calculation, the method of setting prestressing parts is adopted to improve the rigidity of the cavity wall and achieve the same effect. The article compares the two design methods, the latter saving 30% to 50% cavity material, the cost is greatly reduced. Shenzhen billion China Machinery Industry Co., Ltd. (hereinafter referred to billion Hua company) proved to be effective. With the popularization and application of home appliances such as TV sets and video tape recorders, a larger number and higher quality requirements for large and medium-sized plastic injection molded products have been proposed. The mold in the injection molding process, the cavity wall to withstand greater plastic flow pressure and the gate seal the moment before the packing pressure, causing the deformation of the cavity wall. If the deformation exceeds a certain limit, the increase of mold filling material will not only cause flash, but also reduce the cavity pressure and elastic deformation of the sidewall when the material cools and shrinks. When the recovery exceeds the plastic shrinkage , Plastic products are embedded in the surrounding cavity is difficult to stripping, plastic parts damage, serious damage to the mold. Therefore, in large and medium-sized plastic mold design, the cavity wall stiffness issues are very important. This article starts from the calculation of the strength and rigidity of the plastic mold design, carries on the theoretical analysis and economic comparison, puts forward the new design method and makes the experiment. The following is divided into several aspects to discuss.