Abstract: On the basis of the controllability of wall thickness distribution of a mold product by a preform shape, the number of fabrication steps and the cost required for a design and trial formation of a preform forming metal mold are reduced by designing a preform shape such that a thickness distribution of the preform leads a wall thickness distribution of an aimed mold product to thereby obtain a mold product having an ideal rigidity and stability thereof.

Abstract: In order to provide a mold of a shape which has been designed to take into account the deformation occurring during the cooling process, the mold cavity is formed so that the external volume of a molded product obtained by blow molding in this cavity ultimately shrinks by a prescribed percentage of the volume of the mold cavity, and so that in the region of maximum shrinkage the external size of the body portion of the molded product shrinks by a prescribed percentage of the size of the corresponding portion of the mold cavity.

Abstract: In order to provide a mold of a shape which has been designed to take into account the deformation occurring during the cooling process, the mold cavity is formed so that the external volume of a molded product obtained by blow molding in this cavity ultimately shrinks by a prescribed percentage of the volume of the mold cavity, and so that in the region of maximum shrinkage the external size of the body portion of the molded product shrinks by a prescribed percentage of the size of the corresponding portion of the mold cavity.

Abstract: In order to provide a mold of a shape which has been designed to take into account the deformation occurring during the cooling process, the mold cavity is formed so that the difference between the maximum and minimum shrinkage of the external size of the body portion of the molded product relative to the size of the mold cavity has a prescribed value.

Abstract: 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.

Abstract: Simulations are performed for (1) the change in shape of the molten resin when a parison is formed by extruding said resin through the gap between the extruder die and core, (2) the change in shape of the molten resin due to clamping the mold around the extruded parison and blowing compressed air into the parison, and (3) the thermal deformation that will occur in the molded product due to cooling after the molded product, obtained when the molten resin has solidified in the mold, is removed from the mold in a high-temperature state. The shapes of the mold, extruder die and core that will give the desired shape of molded product are determined from the results of these simulations.

Abstract: A cubic Bezier curve is converted to a fifth Bezier curve so as to preserve the gradients at the initial and final points of the cubic Bezier curve and in such a manner that the fifth Bezier curve will assume a shape substantially the same as that of the cubic Bezier curve. Parameters giving points on the cubic Bezier curve are calculated at equal intervals. Points on the cubic Bezier curve are calculated using the calculated parameters and control points defining the cubic Bezier curve. Unit tangent vectors at the initial and final points of the cubic Bezier curve are calculated. Control points defining the fifth Bezier curve are calculated using the calculated parameters, the calculated points on the cubic Bezier curve and the calculated unit tangent vectors at the initial and final points of the cubic Bezier curve.