JPH0524507Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an injection mold for molding a resin molded product having an undercut portion and protrusions such as long ribs.

[Prior Art] A mold as shown in FIG. 5 is known as a mold for molding a resin molded product having protrusions such as undercuts and long ribs by injection molding. That is, on the movable mounting plate 21 at the lower end,
A movable mold 23 is attached via a spacer block 22. A fixed mold 25 is disposed on the movable mold 23 and is fixed to a fixed mounting plate 24 at the upper end. Further, a push-up plate 26 is arranged at the upper center of the movable mounting plate 21.

A through hole 23a is provided in the center of the movable mold 23, and a lower end thereof is rotatably supported by the push-up plate 26, and a molded product P is provided in the through hole 23a.
A push-up cam 27 for pushing out is inserted. A part of the push-up cam 27 is connected to the undercut portion P3 of the first protrusion P1 of the molded product P.
Slanted part 2 for extracting the molded protrusion 27b at the upper end
7a is provided. A backing plate 28 on which the push-up cam 27 comes into sliding contact is attached to the lower part of the center of the movable mold 23 . The movable mold 23, fixed mold 25 and push-up cam 27 cause the first protrusion P to
A cavity 29 is formed for molding a molded product P having first and second protrusions P2.

After molding the molded product P in the cavity 29, the movable mold 23 is separated from the fixed mold 25, and the sixth
As shown in the figure, the push-up cam 27 is pushed up. Then, the diagonal portion 27a of the push-up cam 27 comes into contact with the backing plate 28 and slides, and the push-up cam 27 is pushed up in the diagonal direction. The molded protrusion 27b is extracted.

[Problem to be solved by the invention] However, in the conventional injection mold described above, in order to extract the molding protrusion 27b from the undercut portion P3 of the molded product P, the oblique portion 2 of the push-up cam 27 is
7a is applied to the backing plate 28 in many cases just before the second protrusion P2 of the molded product P is released from the mold. If the slanted part 27a of the push-up cam 27 hits the backing plate 28 too early, as shown in FIG. When pushed up, the push-up cam 27 moves in a certain diagonal direction, so the upper right end of the push-up cam 27 comes into contact with the second protrusion P2 of the molded product P, damaging or deforming the second protrusion P2. A dot is produced.

On the other hand, the slanted part 27a of the push-up cam 27 is
8 late, the molded protrusion 27 of the push-up cam 27
b may not move by the amount necessary to escape from the undercut portion P3 of the molded product P, and in that case, there is a risk that the undercut portion P3 of the molded product P may be damaged and become a defective product. Furthermore, the distance between the end of the push-up cam 27 and the second protrusion P2 of the molded product P when the push-up cam 27 tilts is as follows:
In view of the strength of the push-up cam 27, etc., it is not possible to ensure a large size.

Therefore, there is a problem in that it is difficult to push up the molded product P by the push-up cam 27 while holding it in a predetermined shape and to extract the molded protrusion 27b of the push-up cam 27 from the undercut portion P3.

The purpose of this invention is to be able to easily extract the molded protrusion of the push-up cam from the undercut of the first protrusion of the molded product, and to avoid damaging or deforming the second protrusion of the molded product. The object of the present invention is to provide a mold for injection molding that can smoothly release a molded product.

[Means for Solving the Problems] In order to achieve the above object, the injection molding mold of the present invention has a first undercut portion that protrudes from the main body portion and extends in a direction substantially perpendicular to the direction of the protrusion. An injection mold for forming a molded product having a protrusion and a second protrusion protruding in substantially the same direction as the first protrusion, the injection mold comprising: a fixed mold; A movable mold is arranged to be movable in substantially the same direction as the protruding direction of the protrusion, and forms a cavity for molding the molded product between the fixed mold and the fixed mold during mold clamping, and the fixed mold and the movable mold. In either of them, the first protrusion has a through hole extending in substantially the same direction as the protruding direction, and the first protrusion is movably fitted loosely into the through hole, and the tip of the first protrusion is inserted into the through hole when the mold is clamped. When the mold is opened, the tip protrudes from the through hole and is rotatable around the push-up cam and the base end of the push-up cam that pushes out the molded product between the first projection and the second projection. a push-up member that moves the push-up cam in and out of the through-hole by approaching and separating from the mold having the through-hole; A molding protrusion protruding from the cam surface is formed on one side of the push-up cam, and is inclined so that the closer to the proximal end of the push-up cam, the closer it is to the cam surface in the through hole. a first inclined part for rotating the push-up cam in a direction in which the molded protrusion is pulled out from the undercut part by moving the push-up cam; The molded protrusion is formed on the undercut side and is inclined on the opposite side to the first inclined part, and slides on the cam surface after the molded protrusion is extracted from the undercut part, thereby changing the extraction direction of the molded protrusion. a second inclined portion for restricting the rotation of the push-up cam toward the cam surface; and a second inclined portion for urging the push-up cam toward the cam surface in order to bring the first inclined portion and the second inclined portion into contact with the cam surface. The configuration includes a biasing member that

[Function] By adopting the above configuration, when the injection mold is closed, a cavity is formed between the fixed mold and the movable mold, and a push-up cam is formed in the through hole provided in either mold. The tip is recessed. In this state, molten resin is injected into the cavity by injection molding, and when the molten resin is cooled and solidified, a molded product including a first protrusion having an undercut portion and a second protrusion is formed. Ru.
At this time, the molded protrusion of the push-up cam is engaged with the undercut portion.

When the molded product is removed from both molds when the mold is opened, the push-up member moves toward the side of the mold having the through hole.
With this movement, the push-up cam is projected from the through hole, and the molded product is extruded between the first projection and the second projection. At the beginning of this extrusion, the forming protrusion of the push-up cam remains engaged with the undercut.

As the push-up cam continues to move and the first inclined portion reaches the cam surface within the through hole, the first inclined portion slides on the cam surface. The first inclined portion is inclined so as to approach the cam surface closer to the base end of the push-up cam.
Therefore, as the push-up cam moves, a force that rotates the push-up cam in the direction in which the molded protrusion is extracted from the undercut portion acts on the first inclined portion.

When the first inclined portion passes through the cam surface due to the movement of the push-up cam, the molded protrusion is extracted from the undercut portion. Subsequently, a second inclined part inclined on the opposite side to the first inclined part slides on the cam surface. This sliding movement restricts the rotation of the push-up cam in the direction in which the molded protrusion is extracted.

As described above, when the first and second inclined portions pass through the cam surface, the push-up cam is urged toward the cam surface by the urging member. Therefore, both inclined portions reliably slide on the cam surface.

Therefore, after the molded protrusion of the push-up cam comes out of the undercut, the tip of the push-up cam does not rotate in the extraction direction more than necessary. For this reason,
In the molded product, the first part has an undercut part.
Although the protrusion and the second protrusion protrude from the main body in substantially the same direction, the molded protrusion reliably comes out of the undercut, and the second protrusion
There is no interference with the protrusions of the

[Example] Below are examples 1 to 4 that embody the present invention.
This will be explained based on the diagram.

The injection molding die of this example is for forming a molded product P shown in FIG. 3 by injection molding. This molded product P includes a main body P0, a first protrusion P1, and a second protrusion P2. The first projection P1 projects downward from the main body 0.
The second protrusion P2 protrudes downward from the vicinity of the first protrusion P1 in the main body P0. Therefore, the protrusion direction of the second protrusion P2 is substantially the same as the protrusion direction of the first protrusion P1. The first protrusion P1 is formed with an undercut P3 extending in a direction substantially perpendicular to the protrusion direction (in the left-right direction in FIG. 3).

As shown in FIG. 1, the injection mold of this embodiment includes a fixed mold 5 and a movable mold 3 disposed below the fixed mold. The fixed mold 5 is fixed to the lower surface of the fixed mounting plate 4. Furthermore, the movable mold 3 is mounted on the movable mounting plate 1 via a spacer block 2.

The movable mold 3 is provided with through holes 3a vertically extending therethrough. A backing plate 9 having a cam surface 9b is incorporated into the lower end of the through hole 3a. Also, movable type 3
On the right side of the through hole 3a in the upper part, there is a molded product P.
A hole 3b for forming a second protrusion P2 extends downward.

A push-up cam 7 is movably fitted loosely into the through hole 3a. This push-up cam 7 constitutes a cavity 8 for molding the molded product P together with the movable mold 3 and the fixed mold 5. The tip end (upper end in FIG. 1) of the push-up cam 7 sinks into the through hole 3a during mold clamping when the movable mold 3 contacts the fixed mold 5 (see FIG. 1). Further, the tip of the push-up cam 7 is connected to the fixed mold 5.
When the movable mold 3 separates downward from the mold opening (second,
3) protrudes from the through hole 3a, and pushes the molded product P upward between the first protrusion P1 and the second protrusion P2. A molding protrusion 7c for molding the undercut portion P3 of the molded product P is protruded from the tip of one side (left side in FIG. 1) of the push-up cam 7.

A push-up member 6 is disposed between the movable die 3 and the movable mounting plate 1 so as to be movable up and down. A lower end portion of a push-up cam 7 is rotatably connected to the push-up member 6 by a shaft 6a. By approaching and separating from the movable die 3, the push-up member 6 moves the push-up cam 7 into the through hole 3.
Make it appear from a.

A first inclined portion 7a is formed on one side of the push-up cam 7 (the left side in FIG. 1). The first inclined portion 7a is inclined so that the closer to the base end (lower end in FIG. 1) of the push-up cam 7, the closer it approaches the cam surface 9b inside the through hole 3a. The first inclined portion 7a is for rotating the push-up cam 7 in the direction in which the molding protrusion 7c is pulled out from the undercut portion P3 by sliding on the cam surface 9b when the mold is opened.

A first inclined portion 7a on one side of the push-up cam 7
A second inclined portion 7b is formed closer to the base end of the push-up cam 7, that is, below the first inclined portion 7a. The second inclined portion 7b is inclined on the opposite side to the first inclined portion 7a. The second inclined portion 7b slides on the cam surface 9b after the molded protrusion 7c is extracted from the undercut portion P3, thereby allowing the push-up cam 7 to rotate in the direction in which the molded protrusion 7c is extracted. The purpose is to regulate the

Further, in the backing plate 9, on the other side of the push-up cam 7, a hole 9a is provided which extends in a direction perpendicular to the through hole 3a, as shown in FIG. A spring 10 as a biasing member is inserted into this hole 9a, and the push-up cam 7 is moved toward the cam surface 9b in order to bring the first inclined portion 7a and the second inclined portion 7b into contact with the cam surface 9b. It is biased towards.

The functions and effects of the injection mold constructed as described above will be explained.

During mold clamping when the movable mold 3 is in contact with the fixed mold 5 (first
(see figure), a cavity 8 is formed between both molds 5 and 3, and the tip of a push-up cam 7 is inserted into a through hole 3a formed through the movable mold 3.
In this state, a molten resin is injected into the cavity 8 by injection molding, and when the molten resin is cooled and solidified, a molded resin is formed which includes a first protrusion P1 and a second protrusion P2 having an undercut portion P3. Product P is formed. At this time, the molded protrusion 7c of the push-up cam 7 is engaged with the undercut portion P3.

When the molded product P is removed from both molds 5 and 3 when the molds are opened, the movable mold 3 is separated downward from the fixed mold 5. The push-up member 6 moves upward to approach the movable mold 3. With this upward movement, the tip of the push-up cam 7 is projected upward from the through hole 3a, and the molded product P is pushed up between the first projection P1 and the second projection P2. At the beginning of this push-up, the molded protrusion 7c of the push-up cam 7 remains engaged with the undercut portion P3.

As the upward movement of the push-up cam 7 progresses, the first inclined portion 7
When a reaches the cam surface 9b in the through hole 3a (see FIG. 2), the first inclined portion 7a slides on the cam surface 9b. The first inclined portion 7a is inclined such that the lower side of the push-up cam 7, the closer it approaches the cam surface 9b. Therefore, as the push-up cam 7 moves upward, the first inclined portion 7
A force acts on a to rotate the push-up cam 7 in the direction in which the molded protrusion 7c is extracted from the undercut portion P3 (clockwise in FIG. 2).

When the first inclined portion 7a passes the cam surface 9b due to the upward movement of the push-up cam 7, the molded protrusion 7c is completely extracted from the undercut portion P3. continuation,
A second inclined part 7a is inclined on the opposite side to the first inclined part 7a.
The inclined portion 7b slides on the cam surface 9b (see FIG. 3).

At this time, the second inclined portion 7b of the push-up cam 7 is
When the push-up cam 7 moves upward, its upper right end
It has an inclination angle that does not interfere with the protrusion P2. That is, by sliding the first inclined portion 7a with respect to the cam surface 9b, the push-up cam 7 is moved straight upward at the left and right position when the molded protrusion 7c is extracted from the undercut portion P3 of the molded product P. It has an inclination angle that moves to . Therefore, due to the sliding of the second inclined portion 7b, the molded protrusion 7
The rotation of the push-up cam 7 in the extraction direction of c is restricted.

As described above, the first and second inclined portions 7a, 7b
When passing through the cam surface 9b, the push-up cam 7 is urged toward the cam surface 9b by the spring 10 from the other side (right side). Therefore, both inclined portions 7a and 7b reliably slide on the cam surface 9b.

Therefore, after the molded protrusion 7c of the push-up cam 7 comes out of the undercut portion P3, the tip of the push-up cam 7 does not rotate in the extraction direction more than necessary. Therefore, in the molded product P, although the first protrusion P1 and the second protrusion P2 having the undercut portion P3 protrude from the main body P0 in substantially the same direction (downward in this case), , the molded protrusion 7c reliably comes out of the undercut portion P3. Moreover, even if the gap between both the protrusions P1 and P2 is small, the tip of the push-up cam 7 will not interfere with the second protrusion P2.

As mentioned above, the injection mold of this example is
Since the push-up cam 7 is provided with the first sloped portion 7a and the second sloped portion 7b following the first sloped portion 7a, the molded protrusion 7c can be easily extracted from the undercut portion P3 of the molded product P. Furthermore, after the molded protrusion 7c is extracted, the push-up cam 7 is pushed upward in its left and right positions, so that the molded product P is not damaged or deformed. The mold release can be performed smoothly.

In the above embodiment, the movable mold 3 is provided with the through hole 3a, but instead of this, the fixed mold 5 may be provided with the through hole 3a, and the push-up cam 7 may be inserted into the through hole 3a.

[Effects of the invention] The injection mold of the invention allows the molding protrusion of the push-up cam to be easily extracted from the undercut part of the first protrusion of the molded product, and the molding protrusion of the push-up cam can be easily extracted from the undercut of the first protrusion of the molded product. This has the effect that the molded product can be released smoothly without damaging or deforming the molded product.

[Brief explanation of the drawing]

1 to 4 are views showing embodiments of the present invention, in which FIG. 1 is a sectional view showing an injection mold, and FIG. 2 is a sectional view showing an injection mold.
3 and 3 are sectional views of the injection molding die showing the molded product being released from the mold, and FIG. 4 is an enlarged sectional view of the injection molding die showing the state in which the push-up cam is in contact with the backing plate.
5 to 7 are diagrams showing a conventional example, in which FIG. 5 is a sectional view showing an injection mold, and FIGS. 6 and 7 are injection molds showing the release state of a molded product. FIG. 3... Movable type, 3a... Through hole, 5... Fixed type, 6... Push-up member, 6a... Shaft, 7... Push-up cam, 7a... First inclined part, 7b... Second Inclined portion, 7c... Molded protrusion, 8... Cavity, 9b
...Cam surface, 10... Spring as biasing member, P... Molded product, P0... Main body, P1... First protrusion, P2... Second protrusion, P3... Undercut part .

Claims (1)

[Claims for Utility Model Registration] An undercut portion P3 that protrudes from the main body P0 and extends in a direction substantially perpendicular to the direction of the protrusion.
a first protrusion P1 having a first protrusion P1;
An injection mold for forming a molded product P including a second protrusion P2 protruding in substantially the same direction as the fixed mold 5; and a protrusion direction of the first protrusion P1. a movable mold 3 which is arranged to be movable in substantially the same direction as the fixed mold 5 and forms a cavity 8 for molding the molded product P between the fixed mold 5 and the fixed mold 3 during mold clamping; In either case, a through-hole 3a is provided extending in substantially the same direction as the protruding direction of the first protrusion P1; Immerse yourself in 3a,
A push-up cam 7 whose tip protrudes from the through hole 3a when the mold is opened and pushes out the molded product P between the first protrusion P1 and the second protrusion P2; By approaching and separating from the mold 3 having the through hole 3a, the push-up cam 7 is connected rotatably to the through hole 3a.
a push-up member 6 that protrudes and retracts from the push-up member 6; a molding protrusion 7c that projects from the tip of one side of the push-up cam 7 in order to mold the undercut portion P3 of the molded product P; , the undercut portion P3 is inclined so that the base end side of the push-up cam 7 approaches the cam surface 9b in the through hole 3a, and slides on the cam surface 9b when the mold is opened.
a first inclined portion 7a for rotating the push-up cam 7 in the direction in which the molding protrusion 7c is pulled out; and a base end portion of the push-up cam 7 that is closer to the first inclined portion 7a on one side of the push-up cam 7. The formed protrusion 7c is formed on the side and is inclined on the opposite side to the first inclined part 7a, and after the formed protrusion 7c is extracted from the undercut part P3, the formed protrusion 7c slides on the cam surface 9b. A second sloped part 7b for restricting the rotation of the push-up cam 7 in the direction in which the push-up cam 7c is pulled out; An injection mold characterized by comprising a biasing member 10 that biases the push-up cam 7 toward the cam surface 9b.