JP7300354B2 - ELASTIC MOLD AND METHOD FOR MANUFACTURING MOLDED PRODUCT - Google Patents

Description

The present invention relates to elastic molds and methods of manufacturing molded articles.

An elastic mold used in a molding method in which a mold is filled with a molding material, the molding material is solidified, and then the mold is expanded by an air pressure difference to take out a molded product. An elastic mold having a film thickness of 1 to 5 mm and a film hardness of 10 to 60 [value measured by JIS-K6301 spring hardness test (A type)] is disclosed ( See Patent Document 1).

Also, an elastic mold used in a molding method for taking out a molded product by expanding the mold due to an air pressure difference, wherein the mold is made of a crosslinked fluorosilicone rubber-containing elastomer, and the fluorosilicone rubber-containing elastomer is a fluorosilicone rubber-containing elastomer. An elastic mold comprising 30 to 99.9 parts by weight of silicone rubber and 70 to 0.1 parts by weight of silicone rubber is disclosed (see Patent Document 2).

Japanese Patent No. 4070898 Japanese Patent No. 4210000

The elastic molding die is provided with an opening serving as an ejection port for the molded product and an injection port for the molding material. An elastic molding die is installed with the opening facing upward, a liquid molding material is injected into the cavity through the opening, and the molding material is solidified to produce a molded product. When a liquid molding material is injected into the elastic molding die, most of the air in the cavity escapes from the opening, but some air remains in the upwardly convex portion of the cavity, forming air pockets. There is something. If the molding material is solidified in the presence of air pockets, the air pockets will not be molded and the shape of the molded product will be incomplete. For this reason, conventionally, after the molding material is injected into the elastic molding die, the excess air in the cavity is discharged by a technique such as compressing the elastic molding die.

SUMMARY OF THE INVENTION An object of the present invention is to make it possible to reduce air entrapment in a cavity of an elastic mold without requiring extra man-hours when a liquid molding material is injected into the cavity of the elastic molding die.

The elastic molding die according to the first aspect is made of silicone rubber and is elastically stretchable, and has a mold body formed with a cavity for molding a molded product by injecting a liquid molding material into the interior. an opening provided in the mold body for taking out the molded product from the hollow portion; and an air release portion provided in a portion of the hollow portion that protrudes upward when the molding material is injected; have

In this elastic molding die, an air vent is provided in a portion of the hollow portion that protrudes upward when the liquid molding material is injected, so the air collected in the portion is discharged to the outside from the air vent.

A second aspect is the elastic mold according to the first aspect, wherein the maximum inner dimension of the cavity is formed to be larger than the maximum opening width of the opening.

In this elastic mold, since the maximum internal dimension of the cavity is larger than the maximum opening width of the opening, it is possible to manufacture a molded article having a so-called undercut. Even such a molded product can be demolded by deforming the elastic mold.

A third aspect is the elastic mold according to the first aspect or the second aspect, wherein a brim-shaped base is integrally provided around the opening.

In this elastic mold, since a brim-shaped base is integrally provided around the opening, by holding the base, unnecessary deformation of the cavity can be suppressed, and the elastic mold in the molding apparatus can be can be easily held.

A fourth aspect is the elastic mold according to the third aspect, wherein the base portion is provided with a tapered portion whose diameter increases as it separates from the opening portion in the direction in which the molded product is taken out.

In this elastic molding die, since the tapered portion is provided at the base portion, the periphery of the opening is easily deformed compared to the case where the tapered portion is not provided. Therefore, it becomes easier to remove the molded product from the elastic mold. Also, the durability of the elastic mold can be improved.

A method for manufacturing a molded product according to a fifth aspect includes a mold body that is made of silicone rubber and that is elastically expandable and has a cavity formed therein for molding a molded product by injecting a molding material. an opening provided in the mold body for taking out the molded product from the hollow portion; and an air release portion provided in a portion of the hollow portion that protrudes upward when the molding material is injected; Using an elastic molding die having a a first step of discharging and filling the cavity with the molding material; a second step of solidifying the molding material in the cavity; and a third step of taking out.

In this method for manufacturing a molded article, in the first step, when the molding material is injected into the cavity through the opening with the opening facing upward, the cavity becomes convex upward through the air vent. Excess air can be expelled from the part. Therefore, it is possible to reduce the amount of air trapped in the hollow portion without requiring extra man-hours.

According to the present invention, when a liquid molding material is injected into the cavity of the elastic molding die, it is possible to reduce air entrapment in the cavity without requiring extra man-hours.

1 is a front view showing an elastic mold according to this embodiment; FIG. FIG. 2 is a perspective view showing the elastic molding die according to the present embodiment upside down. (A) is an enlarged cross-sectional view of a portion A in FIG. 1, showing a through hole as an example of an air vent. (B) is an enlarged cross-sectional view of the A portion of FIG. 1, showing a slit with a V-shaped cross section as an example of the air vent. (A) is an enlarged front view showing a through hole as an example of an air vent. (B) is an enlarged front view showing a cross-shaped slit as an example of an air vent. (C) is an enlarged front view showing a state in which the slit of (B) is opened. (D) is an enlarged front view showing a cross-shaped slit with a V-shaped cross section as an example of an air vent. (E) is an enlarged front view showing a state in which the slit of (D) is opened. (A) is a partial cross-sectional view showing an example in which the circumference of the opening in the base is flat. (B) is a partial cross-sectional view showing an example in which a tapered portion is provided around the opening in the base. FIG. 4 is a cross-sectional view showing a state in which a liquid molding material is injected into an elastic molding die, a rod is inserted into the molding material, and the rod is supported by a support member. (A) is an enlarged cross-sectional view of a portion B of FIG. 6, showing a state in which an air reservoir is formed in a portion of the hollow portion that protrudes upward when the molding material is injected. (B) is an enlarged cross-sectional view of the B portion of FIG. 6, showing a state in which the air in the air reservoir is discharged from the through hole. (C) is an enlarged cross-sectional view of the B portion of FIG. 6, showing a state in which air pockets are eliminated. (A) is an enlarged cross-sectional view of a portion B of FIG. 6, showing a state in which an air reservoir is formed in a portion of the hollow portion that protrudes upward when the molding material is injected. (B) is an enlarged cross-sectional view of the B portion of FIG. 6, showing a state in which the air in the air pool is discharged from the V-shaped cross-sectional slit. (C) is an enlarged cross-sectional view of the B portion of FIG. 6, showing a state in which air pockets are eliminated. FIG. 7 is a sectional view showing a state in which the molding material is solidified in FIG. 6; FIG. 10 is a cross-sectional view showing a state in which the elastic mold is inflated by an air pressure difference in FIG. 9; It is a front view which shows the completed molding.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments for carrying out the present invention will be described based on the drawings. 1 and 2, an elastic mold 10 according to this embodiment has a mold body 12, an opening 14, and an air vent 16. As shown in FIG.

The mold body 12 is made of silicone rubber and is elastically expandable. Inside the mold body 12, a cavity 22 is formed into which the liquid molding material 18 is injected to mold the molding 20. As shown in FIG. The shape of the hollow portion 22 is a three-dimensional shape corresponding to the outer shape of the molded product 20 . A molding 20 is manufactured by solidifying the molding material 18 in the cavity 22 . The molded product 20 is, for example, an ice cream stick with an animal-like character (FIG. 11). The molding material 18 is the material for this popsicle stick.

The solidification is not limited to solidification by cooling, but includes solidification by heating, solidification over time, and the like. Moreover, the molded product 20 is not limited to a hard one, and includes an elastic body. Therefore, specific examples of the molded product 20 include three-dimensional objects such as ice candy, chocolate candy, baked sweets, gummy candies, erasers, plastic models, and dolls.

The hardness of the silicone rubber is, for example, 30 degrees or less, and may be 20 degrees or less. This hardness is a value measured by a JIS-K6301 spring type hardness test (A type). By using a highly heat-resistant silicone rubber, it is also possible to bake the elastic mold 10 into which the molding material 18 is injected in an oven to produce baked goods.

In FIG. 6, the maximum internal dimension W of the cavity 22 is formed larger than the maximum opening width w of the opening 14 . That is, there is a relationship of W>w. In other words, the hollow portion 22 has a so-called undercut, which is a portion that cannot be demolded unless the mold body 12 is deformed or the mold body 12 is not a split type. Since the mold body 12 is elastically stretchable, it is possible to remove the mold even if there is an undercut.

In FIG. 2 , the opening 14 is provided in the mold body 12 and is a part for taking out the molded product 20 from the cavity 22 . The opening 14 also serves as an injection port for injecting the liquid molding material 18 into the cavity 22 . Note that the inlet and the opening 14 serving as the outlet may be provided separately.

In FIGS. 2 and 5A, a brim-shaped base 24 is integrally provided around the opening 14 . The base portion 24 is formed, for example, in a circular shape and has an opening 14 formed in the center. For example, a cylindrical wall portion 26 is erected on the outer periphery of the base portion 24 . Note that the configuration of the base 24 is not limited to this. In the example shown in FIG. 5(B), the base portion 24 is provided with a tapered portion 32 whose diameter increases with increasing distance in the direction of arrow U, which is the direction in which the molded product 20 (FIG. 10) is removed from the opening 14. .

A support member 28 can be attached to the inner side of the wall portion 26 during molding. The support member 28 is formed, for example, in a disk shape so as to fit inside the cylindrical wall portion 26 . A hole 28A into which the rod 30 is inserted is formed in the central portion of the support member 28. As shown in FIG. The rod 30 is a member that serves as a handle portion of the molded product 20 . As shown in FIG. 6, when the molded product 20 is molded, the rod 30 is fitted into the hole 28A of the support member 28 and supported.

1 to 3 and 6, the air vent portion 16 is provided in a portion of the hollow portion 22 of the mold body 12 that protrudes upward when the molding material 18 is injected. When the molding material 18 is injected, the opening 14 serving as an injection port for the molding material 18 is directed upward. At this time, the upwardly convex portion is the tip portion of the arm 42 . Therefore, in the illustrated example, the air vents 16 are provided at the tip portions of the left and right arms 42, respectively. In the upright state (FIG. 1) of the elastic molding die 10 (character), the air vent portion 16 is provided in a portion of the hollow portion 22 that protrudes downward. The shape, position, number, etc. of the air vents 16 can be changed as appropriate according to the shape of the hollow portion 22 .

As shown in FIGS. 1, 2, 3A, and 4A, the air release portion 16 is, for example, a pinhole having a diameter of about 0.5 mm. is set to a size that does not leak out. The configuration of the air vent portion 16 is not limited to this, and may be, for example, the configurations shown in FIGS. 3(B) and 4(B) to (E).

In the example shown in FIG. 3B, the air vent portion 16 is a slit with a V-shaped cross section. This slit is configured to elastically open and close in response to changes in pressure within the cavity 22 (FIG. 8).

In the example shown in FIG. 4B, the air vent portion 16 is a cross-shaped slit when viewed from the front. A crack growth suppressing portion 34 is formed at the end of the slit. The crack growth suppressing portion 34 is a corresponding circular hole or recess. This cross-shaped slit is configured to elastically open and close as the pressure inside the cavity 22 increases. FIG. 4(C) shows a state in which the slits of FIG. 4(B) are opened.

In the example shown in FIG. 4D, the air vent portion 16 is a cross-shaped slit when viewed from the front and has a V-shaped cross section. A crack growth suppressing portion 34 is formed at the end of the slit. This cross-shaped slit is configured to elastically open and close as the pressure inside the cavity 22 increases. FIG. 4(E) shows a state in which the slits of FIG. 4(D) are opened.

(Action)
The operation of the elastic mold 10 according to this embodiment will be described together with the method of manufacturing the molded product 20. FIG. In the elastic molding die 10, a brim-shaped base portion 24 is integrally provided around the opening portion 14. By holding the base portion 24, unnecessary deformation of the hollow portion 22 is suppressed and the molding apparatus can be operated. It is possible to easily hold the elastic molding die 10 in the .

The method for manufacturing the molded product 20 uses the elastic mold 10 and includes a first step S1 to a third step S3. 6, in the first step S1, the molding material 18 is injected into the hollow portion 22 from the opening 14 with the opening 14 facing upward, and excess air is removed from the upwardly convex portion through the air vent 16. is discharged, and the cavity 22 is filled with the molding material 18 . At this time, the molding material 18 is injected to a position higher than the air vent portion 16, which is an example of the air vent portion 16, so that the pressure around the air vent portion 16 increases. As a result, as shown in FIGS. 7A to 7C, the air 36 accumulated in the upwardly convex portion is discharged from the pinhole in the direction of the arrow OUT. As shown in FIG. 7(C), by adjusting the size and number of the pinholes, the molding material 18 is prevented from leaking out of the pinholes when the cavity 22 is filled with the molding material 18. be able to.

As shown in FIGS. 8A to 8C, when the air vent portion 16 is a slit with a V-shaped cross section, the slit elastically opens and closes as the pressure inside the hollow portion 22 changes. Specifically, when the molding material 18 is injected to a position higher than the slit, the pressure near the slit increases and the slit opens. As a result, the air 36 accumulated in the upwardly convex portion is discharged from the slit in the direction of the arrow OUT. When the injection of the molding material 18 is completed, the slit is restored in the closing direction, thereby suppressing the leakage of the molding material 18 . At this time, the slit does not have to be completely closed.

As described above, in the elastic molding die 10, the air vent portion 16 is provided at a portion of the hollow portion 22 that protrudes upward when the liquid molding material 18 is injected. 16 to the outside.

Mounted on the base 24 inside the wall 26 is a support member 28 in which a rod 30 is fitted. The support member 28 closes the opening 14 . The rod 30 is fitted into the hole 28A of the support member 28 and supported by the frictional force between it and the surrounding portion of the hole 28A. One end of the rod 30 is immersed in the molding material 18 filled in the cavity 22, and the other end of the rod 30 protrudes outside the cavity 22 (above the support member 28).

In FIG. 9, in the second step S2, the molding material 18 inside the hollow portion 22 is solidified. In this embodiment, in order to manufacture the popsicle stick as the molded article 20, the liquid molding material 18, which is the material for the ice cream bar, is frozen and solidified. At this time, as shown in FIGS. 7(C) and 8(C), a portion of the molding material 18 may remain in the air vent portion 16 . This is because fine burrs are removed during die cutting.

Next, in the third step S3, the mold body 12 is expanded by the pressure difference, and the solidified molded product 20 is taken out. Specifically, for example, the mold body 12 is housed in the container 38 and the wall portion 26 is fitted inside the container 38 . Then, the air inside the container 38 is sucked in the direction of the arrow V through the suction port 40 provided in the container 38 to evacuate the container 38 . Then, an air pressure difference is generated between the inside and outside of the mold body 12, and the mold body 12 expands as shown in FIG. In FIG. 10, the mold body 12 is inflated until it comes into close contact with the inner wall of the container 38, but it may be inflated to such an extent that the molded product 20 can be removed from the mold. By removing the supporting member 28 from the rod 30 in the direction of the arrow U and performing die-cutting, the molded product 20 can be obtained (FIG. 11).

In the elastic mold 10, the maximum inner dimension W of the cavity 22 is formed larger than the maximum opening width w of the opening 14, that is, it has an undercut (FIG. 6). Even the molded product 20 having such a shape can be demolded by deforming the elastic mold 10 .

If the inside of the container 38 is returned to the atmospheric pressure, the elastic mold 10 can be restored to its original shape and can be used repeatedly. Further, as shown in FIG. 5B, when the tapered portion 32 is provided on the base portion 24, the opening is larger than that when the tapered portion 32 is not provided (FIG. 5A). The periphery of the portion 14 is easily deformed. Therefore, it becomes easier to remove the molded product 20 from the elastic mold 10 . Moreover, since the tensile stress acting around the opening 14 during demolding is reduced, the durability of the elastic mold 10 can be improved.

As described above, according to the present embodiment, when the liquid molding material 18 is injected into the cavity 22 of the elastic mold 10, air pockets in the cavity 22 can be reduced without requiring extra man-hours. can make it possible. In addition, this makes it possible to form, for example, the arm 42 of the molded product 20, which is likely to be chipped due to air pockets, without chipping up to its tip.

[Other embodiments]
An example of the embodiment of the present invention has been described above, but the embodiment of the present invention is not limited to the above, and can be modified in various ways without departing from the spirit of the present invention. Of course there is.

Although the maximum inner dimension W of the cavity 22 is formed to be larger than the maximum opening width w of the opening 14 (W>w), the size relationship between these dimensions is not limited to this, and W≤W. It may be w.

Moreover, although the brim-shaped base 24 is provided integrally around the opening 14, the base 24 may be provided separately, or the structure may not have the base 24. .

10 Elastic mold 12 Mold body 14 Opening 16 Air vent 18 Molding material 20 Molded product 22 Cavity 24 Base 32 Taper 36 Air S1 First step S2 Second step S3 Third step

Claims (5)

a mold body that is made of silicone rubber and that is elastically expandable and that has a cavity formed therein for molding a molded product by injecting a liquid molding material;
an opening provided in the mold body for taking out the molded product from the cavity;
an air vent portion provided at a portion of the hollow portion that protrudes upward at the time of injection of the molding material , and has a cross-shaped slit when viewed from the front and a V-shaped cross section ;
An elastic mold having a 2. The elastic mold according to claim 1, wherein the maximum inner dimension of said cavity is formed to be larger than the maximum opening width of said opening. 3. The elastic mold according to claim 1, wherein a brim-shaped base is integrally provided around the opening. 4. The elastic mold according to claim 3, wherein the base portion is provided with a tapered portion that increases in diameter as it separates from the opening portion in the ejection direction of the molded product. a mold body that is made of silicone rubber and that is elastically expandable and that has a cavity formed therein for molding a molded article by injecting a molding material;
an opening provided in the mold body for taking out the molded product from the cavity;
an air vent portion provided at a portion of the hollow portion that protrudes upward at the time of injection of the molding material , and has a cross-shaped slit when viewed from the front and a V-shaped cross section ;
Using an elastic mold having
The molding material is injected into the cavity from the opening with the opening facing upward, and excess air is discharged from the upwardly convex portion through the air vent, and the A first step of filling the molding material;
a second step of solidifying the molding material in the cavity;
a third step of expanding the mold body by the pressure difference and taking out the solidified molded product;
A method for producing a molded article having

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