JPH04325217A - Tunnel gate-structure of mold for injection molding - Google Patents

Abstract

PURPOSE:To provide the tunnel gate-structure of the mold for injection molding in which, in such mold for injection molding, especially the breakage of a runner, etc., is prevented, and smooth molding is guaranteed. CONSTITUTION:In the mold for injection molding which molds a desired molded object by injecting molding material into a cavity and by filling the cavity, a gate sprue 11a and the projected part 11b' for an ejector pin 14 are set in almost same direction.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a tunnel gate in an injection mold, particularly a two-plate type mold that is divided into two parts via a parting line.

0002

[Prior Art] Among the injection molds for forming a desired molded product by injecting and filling a molding material into a cavity, a so-called two-plate type mold has a runner placed on the parting line. The runner and the molded product are removed from the mold each time the mold is opened after molding is completed. FIG. 3 shows the structure of such a two-plate injection mold. In the figure, 1 is a fixed side mounting plate, 2 is a fixed side mold plate, 3 is a movable side mold plate, 4 is a receiving plate,
5 is a spacer block, 6 is an ejector plate, 7 is a movable side mounting plate, 8 is a core, 9 is a spool bush, 1
0 is the spool, 11 is the runner, 12 is the cavity, 1
3 is an ejector pin. The fixed side mold plate 2 and the movable side mold plate 3 are opened and closed via the parting line, but when performing molding, the injection from the spool 10 is shown in FIG. 3, which shows the mold in the closed state. The molding material is filled into the cavity 12 through the runner 11. Further, after the molding is completed, the product formed in the cavity 12 is ejected from the mold by the ejector pin 13.

By the way, in the molding process of such a conventional injection mold, the product formed in the cavity 12 is formed by the gate spool 11a as shown in FIG. 4 when the mold is closed immediately after molding is completed. It is connected to the tunnel gate portion, and the two are separated in the subsequent mold opening process. In that case, the protruding portion 11b of the runner 11 is connected to the protruding pin 14 provided on the movable side.
However, when the runner 11 is ejected with the ejecting pin 14, the direction in which the runner 11 comes out is different from the direction in which the tunnel gate portion of the gate spool 11a comes out, so the so-called forced ejection occurs, as shown in FIG. As shown, there were problems such as deformation of the runner portion or breakage of the runner. Furthermore, the broken part may remain in the mold, causing so-called gate stoppage (gate clogging), and may even lead to molding problems such as double pressing of the mold or cavity piece, reducing production efficiency. This was a problem because it caused a decline in In view of such circumstances, the present invention
It is an object of the present invention to provide a tunnel gate structure for an injection molding mold that can prevent runner bending and the like and ensure smooth molding in this type of injection molding mold.

0004

[Means for Solving the Problems] The tunnel gate structure of the injection molding die according to the present invention provides a tunnel gate structure for an injection molding die in which a molding material is injected and filled into a cavity to form a desired molded product. and the protruding portion for the ejecting pin are set in substantially the same direction.

[0005]

[Operation] According to the present invention, since the gate spool and the protruding part for the ejecting pin are set in almost the same direction, the direction in which the protruding part protruded by the ejecting pin is removed and the tunnel gate part from the gate spool is Since the exit direction coincides with the exit direction, no unreasonable force is applied to the runner or the tunnel gate portion in a direction other than the exit direction, thereby preventing breakage accidents.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a tunnel gate structure for an injection mold according to the present invention will be described below with reference to FIGS. 1 and 2, using the same reference numerals for the same members as in the conventional example. In this embodiment as well, a two-plate type injection mold is used as described in the case of the conventional example, but as shown in FIG. They are set in the same direction, that is, both are inclined upward to the right in the figure with respect to the protruding pin 14.

Since the tunnel gate structure of the injection mold according to the present invention is constructed as described above, when performing the molding process, the molding material injected from the spool 10 passes through the runner 11 when the mold is closed. Through cavity 12
This allows the desired molded product to be obtained. On the other hand, after the completion of molding, the protruding part 11b' of the runner 11 is pushed out by the ejecting pin 14 in the mold opening process, but in this case, the protruding part 11b' is moved into the mold along the direction of arrow A as shown in FIG. Get out of. Since the protrusion 11b' is set in substantially the same direction as the gate spool 11a, the tunnel gate portion of the gate spool 11a also comes out of the gate spool 11a along the direction of arrow A, and the protrusion 11b The direction in which the tunnel gate portion comes out from the gate spool 11a coincides with the direction in which the tunnel gate portion comes out from the gate spool 11a. Therefore, no unreasonable force is applied to the runner 11 or the tunnel gate portion, and as a result, deformation or breakage of the runner portion does not occur when the runner 11 is ejected, and molded products and runner portions are removed from the mold. Removal is performed safely and smoothly. Further, since the broken portion does not remain in the mold and cause gate stoppage, production efficiency can be improved as a result.

In the above embodiments, when polycarbonate, polyacetal, polystyrene, polypropylene, etc., which have relatively high hardness in the solidified state after injection molding, are used as the molding material, these molded products are likely to break. In such cases, particularly excellent effects can be exhibited.

[0009]

As described above, according to the present invention, it is possible to prevent breakage of the runner in this type of injection mold, and also prevent damage to the mold and cavity piece by preventing gate stop and double pressing. can do. Further, by ensuring smooth molding in this type of injection mold, there are advantages such as improved production efficiency.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of a mold according to an embodiment of the tunnel gate structure of an injection mold of the present invention.

FIG. 2 is a sectional view of a main part of a mold for explaining the operation of a tunnel gate structure in an embodiment of the tunnel gate structure of the present invention.

FIG. 3 is a longitudinal cross-sectional view of a conventional injection mold.

FIG. 4 is a sectional view of a main part of a conventional injection mold.

FIG. 5 is a sectional view of a main part of a conventional injection mold for explaining the operation of a tunnel gate structure in the mold.

[Explanation of symbols]

1 Fixed side mounting plate 2 Fixed side template 3 Movable side template 4 Receiving plate 5 Spacer block 6 Ejector plate 7 Movable side mounting plate 8 Core 9 Spool bush 10 Spool 11 Runner 12 Cavity 13 Ejector pin 14 Ejection pin

Claims (1)

[Claims] Claim 1: An injection mold for forming a desired molded product by injecting and filling a molding material into a cavity,
A tunnel gate structure characterized in that a gate spool and a protruding portion for an ejecting pin are set in substantially the same direction.