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#142 Two-Stage Ejecting Structure

Category : Structural Components
February22, 2013

The two-stage ejecting structure is a structure in which it is possible to carry out the ejecting operation twice at the time of ejecting the molded article from the core.
Although ejection is done only once in the usual injection mold, since in the case of the two-stage ejecting structure it is possible inside the mold to carry out ejection two times with a time gap between them, this is a mechanism that is very convenient in cases in which the molded item cannot be taken out the mold with only one ejecting operation.

For example, in the case of the stripper plate ejecting structure such as that shown in Fig. 1, since the shape of the molded item is engraved on the stripper plate, it becomes difficult for the molded item to fall freely.

Fig. 1

In view of this, if a two-stage ejecting structure as shown in Fig. 2 is used, it is easily possible to make the molded article fall freely.

Fig. 2

On the other hand, in the structure shown in Fig. 3, a technique has been used in which a runner ejecting plate is provided within the ejector plate thereby making only the runner to be ejected earlier than the molded item. This has the effects of improving the gate cutting ability of the tunnel gate and of reducing the cutting scrap.

Fig. 3

Apart from this, it is also possible to carry out two-stage ejection using other mechanisms. This will be a useful hint for solving problems when techniques have to be devised for the molded article ejection, runner, cutting of the gate, etc.