초록 ▼

When a molten plastic is molded using a metal mold, sufficient cooling time has to elapse before the metal mold is opened, but this cooling time restricts the production per unit time. If a metal mold is opened without sufficient cooling, the plastic undergoes significant deformation by thermal shri

When a molten plastic is molded using a metal mold, sufficient cooling time has to elapse before the metal mold is opened, but this cooling time restricts the production per unit time. If a metal mold is opened without sufficient cooling, the plastic undergoes significant deformation by thermal shrink. If this deformation can be estimated and the metal mold designed so as to make allowance for the anticipated deformation, it will be possible to produce a molding with a shape that is equal to the design dimensions, despite shortening the cooling time. The finite element method is used to obtain the deformation. Mold design can also be performed taking account of the deformation due to the hydrostatic pressure that is produced when the molding is filled with its liquid contents. In addition, as for a portion of an in-mold labelled container which include lamination construction, the deformation due to thermal shrink is not estimated as a container which an in-mold label is not being applied. On this case, we have a method which is simulating deformation after adding parameters relating to the material of this label, said parameters including at least its thermal conductivity and coefficient of linear expansion. The thermal conductivity deformation simulation is by the finite element method. Production per unit time can be increased and metal mold design can be carried out independently of experience.

대표청구항 ▼

[ What is claimed is:] [1.]1. A method for designing a metal mold comprising:simulating the deformation that will occur in the initial shape of a plastic bottle after the plastic bottle has been taken out from the metal mold;calculating the difference between the deformed shape obtained by said simu

[ What is claimed is:] [1.]1. A method for designing a metal mold comprising:simulating the deformation that will occur in the initial shape of a plastic bottle after the plastic bottle has been taken out from the metal mold;calculating the difference between the deformed shape obtained by said simulating and a target molding shape;comparing this difference with a threshold value; andcalculating a change in the initial shape on the basis of this difference when the difference exceeds said threshold value.