JPH0528024Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a molding die having a side gate.

[Prior Art] Conventionally, in order to reliably pour molten resin into the cavity of a mold, a mold having a side gate is often used. In a molding die equipped with such a side gate, the resin part that has been cooled and solidified at the side gate remains in the molded product.
They are connected together. Therefore, in order to separate the molded product from the residual solidified resin at the side gate, the operator uses a tool such as a nipper to cut and remove the solidified residual resin at the side gate one by one. It is done like this.

On the other hand, Utility Model Application No. 55-99822, Utility Model Application No. 57-156317
As is known from Japanese Utility Model Application Publication No. 58-14621, various molds such as edge gates and submarine gates have been proposed, which automatically cut off the remaining portion at the same time as the mold is released.

However, in such conventional molds, when the molded product is released from the mold, the molded product has not yet completely solidified, and when it is automatically cut within the mold, distortion occurs, which significantly impairs the appearance. Further, there is a problem in that the remaining resin in the gate solidifies and flows into the cavity, causing an unexpected situation such as crushing the mold.

Therefore, depending on the molded product, a method may be adopted in which after the remaining part inside the gate and the molded part are cooled and sufficiently solidified, they are released from the mold as one piece and the remaining part is separated.

[Problems to be solved by the invention] However, in the conventional method described above, when cutting the solidified resin residual part at the side gate using a tool such as a nipper, the gate residual part remains on the molded product. It turns out. Here, the amount of protrusion of this remaining portion of the gate is about 0.7 mm or more, which deteriorates the appearance of the molded product. For this reason, the amount of protrusion of the remaining portion of this gate is
In order to reduce the thickness to 0.3 mm or less so that it can be ignored in terms of appearance, it is necessary to remove the remaining portion of the gate in a separate process after cutting with a tool such as a nipper.

In this way, in the past, it took a long time to actually cut the gate, and there was a risk of damaging the molded product during the process of removing the remaining portion of the gate, resulting in poor productivity and low quality of the molded product. There is a problem that it is difficult to obtain a low price.

This idea was made in view of the above-mentioned problems, and the purpose of this idea is to fold the remaining parts of the molded product after it has been released from the mold by hand folding without using tools such as nippers. To provide a molding die that can be reliably removed without deteriorating its appearance.

[Means for Solving the Problems] In order to solve the above-mentioned problems and achieve the purpose, the molding die according to this invention has a side gate that communicates the runner with the cavity, and also has a side gate that allows the molded product to be cooled. A molding die for forming a molded product so that it can be separated from the molded product by hand folding in a residual part formed by a runner and a side gate after solidifying and releasing the mold, the mold being directed from the runner to the cavity and adjacent to the cavity. a first side gate section provided with a plurality of inwardly projecting protrusions so as to sharply reduce the cross-sectional area at the portion where the cross-sectional area is to be formed; and a second side gate portion provided with a recess formed to steeply reduce the cross-sectional area in a portion adjacent to the cavity, the second side gate portion being connected to the first side gate portion. It is characterized in that a concentrated stress generating part surrounded by a protrusion is formed in the remaining part.

[Function] In the mold configured as above,
The residual portion that adheres to the molded product after the mold release operation and remains and hardens at the side gate is set so that it has the minimum cross-sectional area on the gate opening surface where the side gate opens into the cavity, and this portion is It is considered the most vulnerable part. In this way, when cutting this remaining part from the molded product, by bending this remaining part,
The gate can be separated easily and with the amount of protrusion of the remaining portion of the gate extremely small.

In other words, while ensuring a gate flow path (first and second side gate portions) that can accurately transmit the resin pressure during resin inflow into the cavity, it is possible to reduce the stress generation area at the time of separation in the area adjacent to the cavity. Works to form.

[Example] Below, the configuration of an example of the molding die according to this invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a molding die 10 according to an embodiment. Since this molding die 10 has a substantially vertically symmetrical structure with respect to the central axis, only the upper half is shown and the lower half is omitted. are doing.

This molding die 10 includes a fixed die 12, a movable die 14 provided so as to be able to move toward and away from the fixed die 12 along the axial direction, and the movable die 14.
an ejector member 16 slidably attached to the
and a cavity 20 formed between the fixed mold 12 and the movable mold 14 to define the molded product 18.
It is equipped with.

This fixed mold 12 includes a fixed side mounting plate 22 that is attached to a mounting portion (not shown), and a fixed side mold plate 24 that is fixed to this fixed side mounting plate 22 and defines one surface of the cavity 20. . A spool member 26 in which a spool 26a is formed is attached to the fixed side mounting plate 22 and the fixed side template plate 24 through their central portions.

The movable mold 14 includes a movable mounting plate 28, a receiving plate 32 that is spaced apart from the movable mounting plate 28 via a plurality of spacer blocks 30, and a fixed metal plate that is fixed to the receiving plate 32. The mold 12 includes a fixed side mold plate 24 and a movable side mold plate 34 that is in close contact with the fixed side mold plate 24. A recess 36 defining the other surface of the cavity 20 is formed in the surface of the movable mold plate 34 that faces the fixed mold plate 24 . Further, on the above-mentioned surface of the movable side mold plate 34, there are provided a runner 38 that allows the cavity 20 and the spool 26a to communicate with each other, and a side gate 42 (detailed configuration is shown in FIGS. 2 to 4). It is formed. The movable mold 14 is capable of reciprocating along the axial direction by a drive cylinder (not shown).

The ejector member 16 described above is attached to the movable mold 14
Two ejector pins 44a are provided so as to be movable along the axial direction between the movable side mounting plate 28 and the receiving plate 32, and are arranged to penetrate through the receiving plate 32 and the movable side mold plate 34. , 44b are integrally provided in parallel with each other in a state of extending along the axial direction.
Note that one ejector pin 44a is connected to the cavity 2.
A plurality of ejector pins 44b are disposed along the outer circumference of the cavity 20 in order to release the solidified synthetic resin, that is, the molded product, from the mold.
One spool is provided corresponding to the center of the cavity 20 in order to take out the synthetic resin remaining and solidified within the spool 26a.

This ejector member 16 is urged by a coil spring (not shown) so as to come into pressure contact with the movable side mounting plate 28. In this pressed state, the distal end surface of one ejector pin 44a constitutes one side surface of the cavity 20, and the distal end surface of the other ejector pin 44b constitutes the bottom surface of the runner 38.

Due to the elastic force of the coil spring, the ejector member 16 moves halfway with the movable mold 14 during the mold release process described later, and is fixed to the molding machine. After it comes into contact with a provided ejector rod (not shown), it is stopped and moves to the right in the figure relative to the movable mold 14 while compressing the coil spring.

On the other hand, as shown in FIG. 2, the above-mentioned side gate 42 is composed of a passage that allows the runner 38 and the cavity 20 to communicate with each other. a passage portion 42a, and a second passage portion 42a communicating with the first passage portion 42a and located on the runner 38 side.
A passage portion 42b is provided. Here, the cross-sectional area of the first passage portion 42a is set smaller than the cross-sectional area of the second passage portion 42b, and the width A of the first passage portion 42a and the second passage portion 4
The relationship with the width B of 2b is also set so that B>A.

Here, as is clear from FIG. 2, the cross-sectional shape of the second passage portion 42b is set to have a substantially constant size from the runner 38 toward the cavity 20, and Passage portion 42a of
In other words, the opening surface to the cavity 20 (hereinafter referred to as the gate opening surface) has the smallest cross-sectional shape. That is, this first passage section 42
a is a plurality of protrusions 46a protruding into the passage space from the peripheral wall defining the second passage portion 42b;
46b and 46c, it is defined in a narrowed state.

Here, the length D of this first passage portion 42a
The resin remaining on the side gate 42 (hereinafter referred to as the residual portion) is cooled and solidified, and the molded product 1
8, which is bent and cut to determine the length of the remaining portion (hereinafter referred to as the remaining gate portion), that is, the amount of protrusion, and this amount of protrusion is 0.3 It is set to a predetermined value so that it is less than mm.

Further, in order to form a slit at the joint between the residual portion remaining on the side gate 42 and the molded product 18, the lower surface of the first passage portion 42a is tilted downward by an angle θ from the horizontal plane. Slope 4
It is set to consist of 6a ₁ . In other words, the inclined surface _46a1 and the upright side surface defining the cavity 20 constitute a kind of blunt blade, and a slit corresponding to this blade is formed at the joint between the molded product 18 and the remaining portion. will be formed.

On the other hand, as shown in FIGS. 3 and 4, the fixed mold 12 is located opposite to the movable mold plate 34 of the movable mold 14 provided with the side gate 42.
A side gate 42 is provided on the surface of the fixed side template 24.
A recess 48 is formed in communication with the.
This recess 48 is provided in order to strengthen the strength of the remaining portion, with the resin flowing therein and solidifying being formed integrally with the remaining portion. That is, as will be described later, when the operator bends and cuts this remaining portion, the remaining portion does not break in the middle and is cut into a predetermined molded product 18.
It breaks near the surface of the
In order to prevent the thickness from exceeding 0.3 mm, recess 4
The reinforcing portion defined by 8 is configured to be integrally formed with the remaining portion.

Here, the width C of this recess 48 is the width C of the above-mentioned first
It is set to be larger than the width A of the passage portion 42a, so that C>A. Also, this recess 48
The edge on the side of the cavity 20 is set to coincide with the edge of the cavity 20, or to be separated by a maximum of 0.1 mm.

From the molded product 18 injection-molded using the molding die 10 configured as described above, the side gate 4
The operation of removing the remaining portion remaining and solidified in the molded article 2 and integrally connected to the molded product 18 will be described below.

First, the molding operation will be explained. That is, molten resin is injected into the molding die 10 via the spool member 26. The injected molten resin is brought into the cavity 20 via the spool 26a, the runner 38, and the side gate 42 in this order.
The molten resin brought into the cavity 20 in this way is well distributed throughout the cavity.

After the molten resin has been injected into the cavity 20 and the resin is cooled and solidified, the mold release operation of the molded product 18 is started. This mold release operation is started by moving the movable mounting plate 28 to the left in FIG. This movable side mounting plate 28
As the movable mold 14 moves, the movable mold plate 3
4 and the fixed mold plate 24 of the fixed mold 12, and the molded product 18 is separated from the fixed mold 12 at the mold separation surface L defined by the mutual contact surfaces of the fixed mold plate 24 and the fixed mold plate 24 of the fixed mold 12. While sticking to the movable mold 14, it moves to the left side in the figure together with the movable mold 14.

On the other hand, as described above, the ejector member 16 will once move to the left in the figure together with the movable mold 14 due to the biasing force of the coil spring, but the ejector member 16 will move by coming into contact with an ejector rod (not shown). will be suspended. Therefore, the ejector pins 44a and 44b, which were integrally attached to the ejector member 16, protrude relatively from the movable mold 14 to the right in the figure. In response to the protrusion of the ejector pins 44a, 44b, the molded product 18 is pushed out of the cavity 20 and released from the mold.

Here, the above-mentioned molten resin is cooled and solidified within the cavity 20, and at the same time, the side gate 42
The resin remaining inside is also cooled and solidified as a remaining portion, and is released from the mold as an integral part of the molded product 18.

This remaining portion has a recess 48 as described above.
The resin part that flows into the mold and is cooled and solidified here is formed into one piece. The resin portion defined by this recess 48 functions as a reinforcing member for the remaining portion, thereby connecting the remaining portion to the molded product 1.
The attachment strength at the joint with 8 is relatively weakened compared to other parts. In this way, when the operator cuts the remaining part by bending it, a crack will occur in the middle of the remaining part, and the crack will not break at this point. It will be regulated so that cracks occur at the tip.

On the other hand, a slit is formed at the joint surface between this remaining portion and the molded product 18, as described above.
In this way, fold the remaining part and molded product 1.
8 and the remaining portion, the gate opening surface has the minimum cross-sectional area, and the cracks generated from the tip of the slit mentioned above due to bending will generally occur within the gate opening surface having this minimum cross-sectional area. The amount of protrusion of the remaining part of the gate will be kept within the specified dimension of 0.3 mm.

This is because the synthetic resin material is sensitive to the notch effect, and in order to cut the remaining part from the molded article 18,
This method utilizes the fact that when an external force that bends this is applied to the remaining portion, stress concentration occurs at the tip of the slit, and the synthetic resin breaks with a strength that is less than the material strength of the synthetic resin itself.

In this way, the molding die 10 of this embodiment
According to
It is now possible to regulate it within 0.3mm, and as a result,
The molded product 18 and the remaining portion can be separated from each other by simply folding the molded product 18 by hand without using tools such as nippers. As a result, the molded product 18 will not be damaged by tools such as nippers, and the yield of molded products will be improved.

Furthermore, according to the molding die 10 of this embodiment,
Gate processing can be performed simply by bending, and there is no need to perform finishing processing on the gate marks through post-processing. In this way, it becomes possible to achieve a reduction in the cost of the molded product 18 due to the simplification of the processing steps.

It goes without saying that this invention is not limited to the configuration of the one embodiment described above, and can be modified in various ways without departing from the gist of this invention.

For example, in the configuration of the embodiment described above,
Although it has been explained that a slit having an inclined surface _46a1 is formed on one side (lower side) of the gate opening surface,
This invention is not limited to such a configuration, but may be configured as shown in FIG. 5 as a modified example. In the following description of the modified example, the same components as in the above-described embodiment will be denoted by the same reference numerals, and the description thereof will be omitted.

That is, as shown in FIG. 5, in this modification, the portion of the fixed side mold plate 24 of the fixed mold 12 that defines the gate opening surface, in other words, the boundary portion between the side gate 42 and the cavity 20 is A first passage portion 42a is located in the portion of the fixed side template 24 that is located
A protrusion 50 having a substantially inverted triangular cross section is formed so as to protrude inward. The edge corresponding to the top of this protrusion 50 is set to be located within the gate opening surface, and this gate opening surface has a minimum opening area due to this protrusion 50 and the inclined surface _46a1 . is being done.

In this way, in this modification, when the remaining portion of the molded product 18 is cut by bending, the protrusion 50 and the inclined surface 46a ₁ are formed on both sides in the bending direction.
Since there is an edge, regardless of the direction in which the remaining portion is bent, a crack will be formed on the surface opposite to the direction in which it was bent, and this crack will grow toward the protruding portion on the opposite side. It turns out. As a result, the remaining part can be easily removed, and the protrusion amount of the remaining part of the gate can be reduced to less than the predetermined 0.3 mm.
It will be separated from the molded product 18.

In this way, according to this modification, in addition to the effects achieved by the configuration of the embodiment described above,
The unique effect of not having to choose the bending direction can be achieved.

Further, as explained above, after the mold is released, the remaining portion has sufficient strength to be integrated with the molded product, so after the mold is released, the remaining portion can be separated from the molded product by hand folding.

It goes without saying that this invention is not limited to the configuration of the one embodiment described above, and can be modified in various ways without departing from the gist of this invention.

[Effects of the invention] Therefore, according to this invention, the residual portion attached to the molded product after release can be folded by hand without using tools such as nippers, without deteriorating the appearance of the molded product. A molding die is provided that has a gate flow path that can be removed reliably and that can accurately transmit the resin pressure when the resin flows into the cavity.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the structure of an embodiment of the molding die according to this invention; Fig. 2 is a perspective view showing the shape of the side gate in the forming die shown in Fig. 1; A perspective view showing the shape of the recess connected to the side gate shown in the figure; FIG. 4 shows the runner, side gate, and cavity shown in FIG.
A sectional view taken along the X-ray; and FIG. 5 is a half sectional view showing a modification of the configuration of the embodiment. In the figure, 10...molding mold, 12... fixed mold,
14...Movable mold, 16...Ejector member, 1
8... Molded product, 20... Cavity, 22... Fixed side mounting plate, 24... Fixed side template, 26... Spool member, 26a... Spool, 28... Movable side mounting plate, 30... Spacer Block, 32... Receiving plate, 34... Movable side template, 36... Recess, 38...
...Runner, 42...Side gate, 42a...First passage portion, 46a ₁ ...Slope, 42b...Second passage portion, 44a, 44b...Ejector pin, 48...Recess, 50... It is a protrusion.

Claims (1)

[Claims for Utility Model Registration] (1) It has a side gate that communicates the runner and the cavity, and after the molded product is cooled and solidified and released from the mold, in the remaining part formed by the runner and the side gate, A molding die for molding that can be separated from a molded product by hand folding, the molding die being directed from the runner toward the cavity and protruding inward so as to sharply reduce the cross-sectional area at a portion adjacent to the cavity. a first side gate portion provided with a plurality of protrusions; a first side gate portion connected to the first side gate portion and directed from the runner toward the cavity, and having a cross-sectional area steeply decreasing at a portion adjacent to the cavity; a second side gate portion provided with a recess formed as shown in FIG. A molding die characterized by molding a part where concentrated stress occurs. (2) At least one of the protrusions is configured to gradually protrude inward toward the cavity and is formed with an inclined surface along the manual folding direction of the separation. A molding die according to claim 1 of the utility model registration claim. (3) A protrusion that protrudes inward of the concentrated stress generating section is formed at an end of the recess that faces the protrusion on which the inclined surface is formed, of the plurality of protrusions. A molding die according to claim 1 or 2 of the utility model registration claim, characterized in that: