JP2600597Y2 - Injection mold - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection mold having an undercut molding function.

[0002]

2. Description of the Related Art When an undercut portion is formed on a side surface of a molded product to form a projection, a slide core is commonly used. If the projection has a hollow boss shape having a height, a seizure failure such as galling or deformation may occur at the time of mold release. As an example of a device to cope with this, actual fair 1-2
No. 6423 can be cited.

[0003]

[Problem to be solved by the present invention]
In the mold releasing apparatus described in Japanese Patent Application Laid-Open Publication No. H10-157, rack processing is performed on the inclined pin, and pinion processing is performed on the rotating shaft connected to the product part, in order to release the product part while rotating the product part from the undercut part. . An object of the present invention is to provide an injection molding die for smoothly releasing a slide core from a deep undercut portion without performing such special processing.

[0004]

According to the present invention, a slide core having a fixed die and a movable die, and having an under-cut molded portion for forming a projection on a side surface of a molded product is incorporated in the movable die. An insertion pin that forms a hollow portion in the protrusion of the molded product is inserted into the slide core so that it can slide in the axial direction by a certain distance, and the insertion pin is urged in a direction to remove the insertion pin from the protrusion of the molded product. Incorporate a spring. In the fixed type, a rod that pushes the insertion pin by a predetermined amount along the sliding direction of the slide core is slidably inserted. And when closing the mold,
The fixed mold is provided with a driving means for pushing out the rod to insert the insertion pin into the projection of the molded article, and immediately before opening the mold, pulling the rod out and pulling out the insertion pin by a predetermined amount from the projection of the molded article.

[0005]

When the mold is closed, the rod is pushed out and the insertion pin is inserted into the projection of the molded product. Immediately before the mold is opened after molding, the rod is retracted, and the insertion pin is pulled out of the projection of the molded product by a predetermined amount by a spring. Then, when the mold is opened and the slide core is pushed open, the undercut molding portion and the insertion pin come off from the molded product.

[0006]

An embodiment will be described with reference to the drawings. 1 to 3, 1 is a molded product, 2 is a fixed mold, 3 is a movable mold,
Reference numeral 4 denotes a slide core incorporated in the movable mold 3 so as to be slidable in the left and right directions as shown in the figure. The slide core 4 has an undercut forming portion 40 and the undercut forming portion 40 for forming the hollow boss 10 on the side surface of the molded product 1.
Is provided with an insertion pin 5 for inserting its own tip. The insertion pin 5 is slidably inserted into a fitting hole 41 whose axis is parallel to the sliding direction of the slide core 4.
To form a hollow portion. The insertion pin 5 has a stepped shape in the order of a middle diameter portion, a large diameter portion, and a middle diameter portion from the small diameter portion to the right in the drawing, and the fitting hole 41 also has a corresponding stepped hole. It is.

Reference numeral 6 denotes a compression coil spring which is fitted between a stepped portion between the large diameter portion and the medium diameter portion of the fitting hole 41 and the large diameter portion of the insertion pin 5. Product hollow boss 10
It is urged in a direction to pull it out of. Reference numeral 42 denotes a restraining bush for preventing the insertion pin 5 from coming off or restricting the insertion pin 5 to move only a predetermined amount in the pulling direction, and is fixed to the opening of the fitting hole 41.

Reference numeral 7 denotes a slide core 4 pierced in the fixed mold 2.
The rod is slidably inserted into the fitting hole 20 in which the sliding direction and the axis are parallel to each other. The rod is arranged so that the axis is located on the extension of the axis of the insertion pin. The rod 7
The diameter of the root (right end in the figure) is increased, and the fitting hole 20
Also supports this. By setting the large diameter portion of the fitting hole 20 to a predetermined length, the movement stroke of the rod 7 is determined. Reference numeral 8 denotes a hydraulic cylinder fixed to face the fitting hole 20 of the fixed die 2, and the cylinder rod 81 is inserted into the fitting hole 20 and connected to the large diameter portion of the rod 7.
When the cylinder rod 81 is pushed out in this manner, the rod 7 is pushed out by a predetermined amount, and the insertion pin 5 is pushed out by a predetermined amount along the sliding direction of the slide core.

The operation of the above mold is as follows. First, at the time of closing the mold (FIG. 1), the cylinder rod 81 of the hydraulic cylinder 8 is pushed out, and the insertion pin 5 is also pushed out through the rod 7 by a predetermined amount. Inserted. When injection molding is performed in this state, a molded product 1 having a hollow boss 10 on the side surface is formed.

Before the molded article 1 is sufficiently solidified or before the mold is opened, as shown in FIG. 2, the cylinder rod 81 is pulled in, and the rod 7 is housed in the fixed mold 2 so as not to hinder the mold opening. As a result, the insertion pin 5 loses the pressing force in the left direction in the figure, is moved right by the compression coil spring 6, and comes into contact with the stop bush 42 and stops. When the insertion pin 5 moves, its tip is extracted from the hollow boss 10 of the molded product 1 by a predetermined amount.

After the above-described operation of removing the insertion pin 5 by a predetermined amount is completed, the mold is opened. As shown in FIG. 3, when the movable mold 3 separates from the fixed mold 2, the slide core 4 slides in a direction perpendicular to the mold opening direction along an inclined pin (not shown) provided between the fixed mold and the slide core. , Get out of the molded article 1. Therefore, the undercut forming section 40 comes off the molded article 1 and the molded article 1 can be protruded. The molded article 1 is ejected from the movable mold 3 by an eject mechanism (not shown).

[0012]

[Effects of the Invention] In the present invention, the insertion pin is pulled out from the hollow boss of the molded product while holding the undercut molding portion before opening the mold, and then the undercut molding portion is removed. The release resistance applied to the portion is reduced, and the release failure can be reduced. Further, the present invention does not require special processing as in the conventional example, and has a simple structure.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an embodiment of an injection mold according to the present invention when the mold is closed.

FIG. 2 is a sectional view showing a state immediately before the mold opening.

FIG. 3 is a sectional view when the mold is opened.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Molded product 10 Hollow boss (projection) 2 Fixed type 3 Moving type 4 Slide core 40 Undercut molded part 5 Insertion pin 6 Compression coil spring 7 Rod 8 Hydraulic cylinder (drive means)

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B29C 45/26-45/44 B29C 33/44-33/50

Claims (1)

(57) [Scope of request for utility model registration] 1. An injection mold having the following elements. a. Fixed type. b. Mobile type. c. A slide core having an under-cut molded portion, which is incorporated in the movable mold and forms a projection on a side surface of a molded product. d. An insertion pin that is inserted into the slide core so as to be slidable in the axial direction by a predetermined distance, and that forms a hollow portion in the protrusion of the molded product. e. A rod which is slidably inserted into the fixed mold and pushes out the insertion pin by a predetermined amount along the sliding direction of the slide core. f. A spring for urging the insertion pin in a direction to pull it out of the protrusion of the molded product. g. When the mold is closed, the rod is pushed out and the insertion pin is inserted into the projection of the molded product when the mold is closed. Driving means to put out.