JP6279426B2 - Undercut processing jig and undercut processing method - Google Patents

Description

  The present invention relates to an undercut processing jig suitable for processing an undercut provided in a molded product when performing resin injection molding.

Conventionally, when an undercut is formed on a resin molded product having a concave or hole-shaped undercut on the molding surface, an inclined piece or a slide core is provided on the mold. Thus, when the molded resin molded product is removed from the mold, a method of driving the tilting piece and the slide core has been adopted.
In such a method, for example, when using an inclined piece, it is necessary to form an inclined fitting portion corresponding to the inclined piece in the mold, and there is a space for moving the inclined piece when the resin molded product is removed. There is a problem that it is necessary and cannot be applied depending on the product shape of the resin molded product.
Moreover, when using a slide core, since it is necessary to provide the mechanism or shape for sliding and releasing from a metal mold | die, there exists a problem that the structure of metal mold | die itself will become complicated.

  In order to solve these problems, for example, when a rotatable insert block is arranged in a part of a mold element and the wall portion of the molded resin product is bent, the bending deformation is followed. A method is known in which the undercut is released from the insert block when the insert block is rotationally displaced autonomously (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 11-77698

In the method described in Patent Document 1, a coil spring is provided between the insert block and the block main body, and the coil spring returns to the normal position when the insert block is always clamped. Power is given.
With such a configuration, in the method described in Patent Document 1, in a state where the mold is opened, the convex portion of the insert block is in close contact with the resin molded product, and in order to release the resin molded product from this convex portion, This is implemented by rotating the insert block in the direction opposite to the restoring force by driving the upper block provided in the core block to bend a part of the resin molded product.
However, in the method described in Patent Document 1, it is necessary to form an upper block for releasing the resin molded product in a part of the core block. There existed a problem that the process and cost for providing the said upper block were needed.
Therefore, the present invention provides a jig that does not require an additional configuration for removing the jig in the mold for providing an undercut to a resin molded product.

As a configuration for solving the above-described problems, the undercut processing jig of the present invention is an injection mold including an upper mold and a lower mold that are relatively displaced , in order to form an undercut in a molded product, An undercut processing jig provided on either the upper mold or the lower mold,
A rotating piece, a main body part containing the rotating piece, and a spring member arranged between the main body part and the rotating piece to urge the rotating piece to rotate,
The rotary piece has a first cutout part in a part of an outer peripheral surface, and the first cutout part is formed by a convex part corresponding to the shape of the undercut and the injection mold. A contact portion that is in contact with a part of the molded product ,
When the spring member is relatively displaced so that the upper die and the lower die are separated from each other, the convex portion is removed from the undercut , and the contact portion is used to determine whether the molded product is the upper die or the lower die. It is arranged so as to urge the rotary piece in a direction to release from either of them,
It is characterized by that.

According to the present invention, in a jig for forming an undercut in a resin molded product, it is not necessary to provide an additional configuration for removing the jig in the mold.
Therefore, the number of parts of the mold itself can be reduced, and the processing cost can be reduced.
Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

It is sectional drawing which shows the principal part of the injection molding apparatus to which the injection mold of this invention is applied. It is sectional drawing of the principal part which shows the state at the time of injection molding of the undercut processing jig | tool attached to the lower mold | type in the 1st Example. It is sectional drawing of the principal part which shows the state at the time of mold release of the undercut processing jig | tool attached to the lower mold | type in the 1st Example. It is sectional drawing of the principal part which shows the state at the time of the injection molding of the undercut processing jig | tool attached to the lower mold | type in 2nd Example. It is sectional drawing of the principal part which shows the state at the time of mold release of the undercut processing jig | tool attached to the lower mold | type in the 2nd Example.

Embodiments of the present invention will be described below with reference to the drawings.
Example 1
FIG. 1 is a cross-sectional view showing a main part of an injection molding apparatus to which an injection mold according to the present invention is applied.
As shown in FIG. 1, the injection mold 10 of the present invention includes a lower mold 20 that is a movable mold and an upper mold 30 that is a fixed mold. When the lower mold 20 and the upper mold 30 are in contact with each other, a gap having a predetermined shape is formed therein, and a high-temperature molten resin is poured into the gap, whereby the resin molded product 1 having the predetermined shape is molded.
The lower mold 20 and the upper mold 30 of the injection mold 10 are respectively attached to the movable side structure 40 and the fixed side structure 50 of the injection molding apparatus.

The movable side structure 40 includes a movable attachment plate 41 attached to the stroke means (not shown) of the injection molding apparatus, a spacer block 42, and a movable side mold plate 43.
Inside the spacer block 42 are provided an ejector pin 44 and ejector means 45 for driving the ejector pin 44 up and down.
In addition, a concave portion having a shape corresponding to the lower mold 20 of the injection mold 10 is formed in the movable side mold plate 43, and the lower mold 20 is held so as to fit into the concave portion.

The fixed side structure 50 is attached to the casing (not shown) of the injection molding apparatus so as to face the movable side structure 40, and includes a fixed side mounting plate 51, a runner plate 52, and a fixed side structure. Side mold plate 53.
A concave portion having a shape corresponding to the upper mold 30 of the injection mold 10 is formed in the fixed-side mold plate 53, and the upper mold 30 is held so as to fit into the concave portion.
A sprue bushing 54 is disposed inside the fixed side mounting plate 51 and the runner plate 52, and a flow path 55 communicating with the sprue bushing 54 is formed in the fixed side mold plate 53 and the upper mold 30. .
With these configurations, high-temperature molten resin is supplied into the injection mold 10 through the sprue bushing 54 and the flow path 55.

2 and 3 are cross-sectional views of the main part showing the undercut processing jig 21 attached to the lower mold 20 in the first embodiment. 2 shows a state at the time of injection molding in which the lower die 20 and the upper die 30 are brought into contact with each other, and FIG. 3 shows a state at the time of releasing from which the lower die 20 and the upper die 30 are separated.
As shown in FIGS. 2 and 3, an undercut processing jig 21 is attached to the lower mold 20 at a portion corresponding to the width (molding length) of the resin molded product 1.
The undercut processing jig 21 includes a main body 22, a rotary piece 23 in which a notch 23 a is formed in a part of a cylindrical member, and a spring member 24 that biases the rotary piece 23 in the rotation direction. Including.
The main body 22 has a notch formed at a position corresponding to the notch 23a of the rotary piece 23 and a recess corresponding to the outer diameter of the rotary piece 23. 23 is integrated in a manner to be inserted.

At least one convex portion 23b is formed in the cutout portion 23a of the rotary piece 23 at a position where the undercut 2 is formed.
In addition, a gap 25 for mounting the spring member 24 is further formed on the inner peripheral surface of the recess of the main body 22, and when the rotary piece 23 is inserted into the recess of the main body 22, The spring member 24 is disposed in the gap 25 so as to be always biased.
At this time, the gap 25 has an abutting surface 25 a that comes into contact with one end of the spring member 24 in the expansion / contraction direction, and the other end of the spring member 24 is disposed so as to be opened to the concave portion of the main body portion 22.

In the undercut processing jig 21 according to the first embodiment, the spring member 24 is attached to the gap 25 so that the rotary piece 23 becomes the natural length of the spring member 24 at a position where the rotary piece 23 is removed from the undercut 2 of the resin molded product 1. It is done.
As shown in FIG. 2, during mold clamping and injection molding, the upper mold 30 abuts and presses against the notch 23 a of the rotary piece 23, so that the rotary piece 23 compresses the spring member 24 (illustrated). The projection 23b is arranged at a position corresponding to the undercut by rotating clockwise.

When the resin molded product 1 is removed from the undercut processing jig 21 after the injection molding, the upper die 30 is separated from the notch 23a of the rotary piece 23 as shown in FIG. By applying an urging force to return to the length to the rotary piece 23, the rotary piece 23 rotates counterclockwise in the figure, and the convex portion 23 b of the rotary piece 23 is detached from the resin molded product 1 to form an undercut 2.
With such a configuration, the rotary piece 23 is always urged to rotate in the direction in which the convex portion 23b is removed from the undercut 2 by the spring member 24, so that only the operation of releasing the mold clamping and removing the upper die 30 is performed. The convex portion 23 b can be removed from the undercut 2.
Therefore, an additional configuration for releasing the undercut from the lower mold applied to the injection molding becomes unnecessary, and as a result, the number of parts of the mold can be reduced and the processing cost can be reduced.

  Further, the rotary piece 23 is formed by forming a notch in a part of a cylindrical member, and the concave portion of the main body portion 22 is provided with a circle that is substantially the same as the outer circumferential circle of the cylindrical member of the rotary piece 23. By doing so, the outer peripheral surface of the rotary piece 23 is configured to fit freely into the inner peripheral surface of the main body portion 22 without any gaps, so that, for example, the rotary shaft member provided in the insert block of Patent Document 1 is unnecessary. Thus, the structure can be simplified.

(Example 2)
4 and 5 are cross-sectional views of the main part showing the undercut processing jig 21 attached to the lower mold 20 in the second embodiment. 4 shows a state at the time of injection molding in which the lower die 20 and the upper die 30 are brought into contact with each other, and FIG. 5 shows a state at the time of release from which the lower die 20 and the upper die 30 are separated.
As shown in FIGS. 4 and 5, an undercut processing jig 21 is attached to the lower mold 20 at a portion corresponding to the width (molding length) of the resin molded product 1.
Similar to the first embodiment, the undercut processing jig 21 according to the second embodiment includes a main body 22, a rotary piece 23 in which a notch portion 23 a is formed in a part of a cylindrical member, and the rotary piece 23. And a spring member 24 biased in the rotational direction.
The main body 22 has a notch formed at a position corresponding to the notch 23a of the rotary piece 23, and a recess corresponding to the outer diameter of the rotary piece 23. The rotating piece 23 is integrated in an inserted manner.

In the first embodiment shown in FIGS. 2 and 3, the spring member 24 is arranged vertically (upward and downward in the drawing) inside the main body 22, but in the second embodiment shown in FIGS. 4 and 5, A spring member 24 is disposed laterally (in the left-right direction in the figure) inside the main body 22.
That is, a gap 25 for mounting the spring member 24 is further formed on the inner peripheral surface of the concave portion of the main body portion 22, and when the rotary piece 23 is inserted into the concave portion of the main body portion 22, The spring member 24 is disposed in the gap 25 so as to be always biased.
At this time, the gap 25 has abutting surfaces 25 a and 25 b that can come into contact with both ends of the spring member 24 in the expansion / contraction direction.

When removing the undercut 2 from the undercut processing jig 21 of the present invention, as shown in FIG. 4, the upper die 30 abuts against the notch of the rotary piece 23 during injection molding, so that the rotary piece 23 becomes a spring member. 24 is rotated in the direction of compressing (clockwise in the figure) and is arranged at a position where the convex portion 23a protrudes.
As shown in FIG. 5, when the resin mold part 1 is released from the lower die 20, the rotary piece 23 is rotated counterclockwise by the urging force of the spring member 24 when the upper die 30 is separated from the rotary piece 23. The protrusion 23a of the rotary piece 23 is detached from the resin molded product 1 to form an undercut 2.
With these configurations, a gap is formed inside the main body portion 22 and the spring member 24 is disposed sideways. Therefore, when the rotary piece 23 is attached to the main body portion 22, the spring member 24 is held in the gap and attached. Sometimes it does not jump out of the main body 22.
Therefore, when the undercut processing jig 21 is assembled, the positioning of the spring member 24 is facilitated, and the time for assembly and assembly can be shortened.

In addition, this invention is not limited to an above-described Example, Various modifications are included.
For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described.
Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment.
Furthermore, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

DESCRIPTION OF SYMBOLS 1 Resin molding 2 Undercut 10 Injection mold 20 Lower mold 21 Undercut processing jig 22 Main body part 23 Rotating piece 23a Convex part 24 Spring member 30 Upper mold

Claims (7)

In an injection mold including an upper mold and a lower mold that are relatively displaced, in order to form an undercut in a molded product, an undercut processing jig provided in either the upper mold or the lower mold There,
A rotating piece, a main body part containing the rotating piece, and a spring member arranged between the main body part and the rotating piece to urge the rotating piece to rotate,
The rotary piece has a first cutout part in a part of an outer peripheral surface, and the first cutout part is formed by a convex part corresponding to the shape of the undercut and the injection mold. A contact portion that is in contact with a part of the molded product ,
When the spring member is relatively displaced so that the upper die and the lower die are separated from each other, the convex portion is removed from the undercut , and the contact portion is used to determine whether the molded product is the upper die or the lower die. An undercut processing jig, which is disposed so as to urge the rotary piece in a direction to release from one of them. A gap for accommodating the spring member is formed in the recess of the main body,
The undercut processing jig according to claim 1, wherein the rotary piece is formed with a second cutout portion that receives the force of the spring member. The undercut processing jig according to claim 2, wherein the gap is provided with an abutting surface only on one end side in the expansion / contraction direction of the spring member. 3. The undercut processing jig according to claim 2, wherein the gap includes abutting surfaces on both ends of the spring member in the expansion / contraction direction. 4. The rotary piece is formed by processing a cylindrical member, and the concave portion of the main body has an inner peripheral surface having the same diameter as the cylindrical outer peripheral surface of the rotary piece. Item 5. The undercut processing jig according to any one of Items 1 to 4. The upper mold, and the lower mold, for injection molding, which comprises an undercut processing jig according to any of claims 1 to 5 which is provided on one of the upper mold and the lower mold Mold. After creating a molded article using the injection mold according to claim 6, by releasing the clamping of the lower mold and the upper mold, the rotary piece under the force of the spring member undercut processing method but, wherein the convex portion of the rotary piece with the rotating disengaged from the undercut.

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