JP2021120183A - Gate cutting method, mold, injection molding device, and injection molded body - Google Patents

Abstract

To provide a gate cutting method that can reliably separate a molding from a residual body remaining in a gate or runner in injection molding using a side gate, a mold and an injection molding device used for the method, and an injection molded body molded by the method.SOLUTION: By using: first extrusion means 4 that extrudes an injection molded body 7 molded in a molding space 9 by injecting a soft material having a shore A hardness of 90 or less from a side gate 11 toward a core 3 near a connection part 6 between the molding space 9 and the side gate 11 when a mold is opened; and second extrusion means 5 that extrudes a residual body 8 remaining in an injection flow path 10 including the side gate 11 connected to the injection molded body 7 by the connection part 6 toward a cavity 2 near the connection part 6 when the mold is opened, the injection molded body 7 and the residual body 8 are cut and separated by the first extrusion means 4 and the second extrusion means 5 when the mold is opened.SELECTED DRAWING: Figure 2

Description

The present invention relates to a gate cutting method in injection molding using a side gate, a mold and an injection molding apparatus used therein, and an injection molded body molded by the method.

In conventional injection molding, there are a side gate in which a gate is formed between the core and the cavity facing each other so as to be connected to the side surface of the product, a submarine gate in which the gate is formed through the core, and the like (see Patent Document 1). When a side gate is used among these, the molded product and the resin residue are separated by shifting the extrusion timing of the extrusion of the molded product (product) and the resin residue remaining in the runner after the mold is opened. Was.

Japanese Unexamined Patent Publication No. 2019-014068

However, when a soft material having a shore A hardness of 90 or less, for example, a TPO (olefin thermoplastic elastomer) resin having a shore A hardness of about 65 is used for molding, since the material is soft, the molded product and the inside of the gate or runner Even if an attempt is made to divide the residual resin residue due to a difference in extrusion timing, there is a problem that the residue is only stretched and does not divide.

An object of the present invention is a gate cutting method that enables reliable separation of a molded product and a residue remaining in a gate or a runner in injection molding using a side gate, a mold and an injection molding apparatus used for the gate cutting method, and an injection molding apparatus. An object of the present invention is to provide an injection-molded article molded thereby.

Means for Solving Problems and Effects of Invention

The gate cutting method of the present invention for solving the above problems is
A mold in which a molding space and a side gate for injecting a soft material having a shore A hardness of 90 or less into the molding space are formed between the molded core and the cavity facing each other.
A first extrusion means for extruding an injection molded product molded in the molding space toward the core near the connection portion between the molding space and the side gate when the mold is opened.
A second extrusion that is formed in a form connected to the injection molded body and that extrudes the residue remaining in the side gate or the injection flow path including the side gate toward the cavity side in the vicinity of the connection portion when the mold is opened. Means and
The injection-molded article and the residue are cut and separated at the connecting portion by the first extrusion means and the second extrusion means at the time of opening the mold.

Further, the mold of the present invention is a mold used for the gate cutting method, and the injection molding apparatus of the present invention includes the mold, the first extrusion means, and the second extrusion means. At the time of opening, the injection molded body and the residue can be cut at the connection portion by the first extrusion means and the second extrusion means.

According to the present invention, when the cavity is opened away from the core, the injection molded body molded in the molding space and the residue in the injection flow path including the side gate integrally connected to the injection molded body. On the other hand, the first extrusion means pushes the injection molded body side of those connecting portions (connection portions), and the second extrusion means pushes the side gate side in the opposite direction. As a result, a shearing force acts on the connecting portion (connecting portion) to cut the injection molded body in the molding space and the residue in the side gate or the runner. Furthermore, since this shearing force acts with the mold opening, the injection molded body and the residue can be automatically cut at the time of mold opening, and it is not necessary to perform gate cutting later, so that the processing step can be reduced. .. The present invention relates to a side gate, and does not include a submarine gate or a banana gate that is formed through the core. These gates have a problem that clogging is likely to occur when a soft material is used.

The side gate can be formed to have a shape that tapers toward the molding space side. According to this configuration, the apex portion where either or both of the extruded surface of the second extrusion means on the core side or the surface on the cavity side facing the extruded surface is the connection position between the injection molded body and the residue is formed. Since it has a wedge shape with an acute angle, it becomes a more suitable shape by cutting at the connecting portion.

The first extrusion means and the second extrusion means can be provided in the mold. As a result, the gate of the soft material can be cut by simply installing the mold in the injection molding apparatus.

The injection-molded article of the present invention is an injection-molded article of a soft material having a shore A hardness of 90 or less, which is molded by using the gate-cut method of the present invention, and is formed on the main surface on the cavity side at the time of molding. (I) It may have a pressing mark pressed against the extrusion means. Furthermore, the injection-molded article of the present invention may have a gate mark of the side gate on the side surface when the main surface is the upper surface. The presence of these pressing marks and gate marks makes it clear that the gate cutting method of the present invention is applied.

FIG. 5 is a cross-sectional view schematically showing a cross section of a mold of the injection molding apparatus of this embodiment. FIG. 5 is a cross-sectional view schematically showing a stage immediately after cooling and solidification in the mold of FIG. FIG. 5 is a cross-sectional view schematically showing the first stage of mold opening in the mold of FIG. FIG. 5 is a cross-sectional view schematically showing a second stage of mold opening in the mold of FIG. FIG. 5 is a cross-sectional view schematically showing a step of projecting a molded product in the mold of FIG. A partially enlarged view of FIG. The perspective view which showed an example of an injection-molded article and a residue.

Hereinafter, examples of the present invention will be described with reference to the drawings.

The injection molding apparatus 100 shown in FIGS. 1 to 5 has a mold 1. The mold 1 has a core 3 and a cavity 2, and a molding space 9 and an injection flow path 10 are formed between the molded core 3 and the cavity 2 facing each other, as shown in FIG. Will be done. The tip of the injection flow path 10 is connected to the molding space 9, and the tip (connection portion) thereof is indicated by reference numeral 6.

The injection flow path 10 includes at least a side gate 11. As shown in FIG. 1, the injection flow path 10 here includes a side gate 11 whose tip is connected to the molding space 9 and a runner 12 whose tip communicates with the rear end side of the side gate 11. Both are formed between the molded core 3 and the cavity 2 facing each other. Further, a runner 12 communicates with a spool (not shown) on the cavity 2 side in the injection flow path 10, and an injection nozzle (not shown) of the injection molding apparatus 100 is connected to this spool. The molding material is injected into the spool from the injection nozzle in a molten state, passes through the runner 12, and flows into the molding space 9 from the tip (connecting portion 6) of the side gate 11. After that, when it is cooled and solidified, as shown in FIG. 2, an injection molded product 7 as a product is formed in the molding space 9. On the other hand, in the injection flow path 10, the material remaining in the injection flow path 10 is solidified to form the residue 8.

The molding material of the injection molded product 7 is a soft material having a shore A hardness of 90 or less (more preferably, a soft material having a shore A hardness of 80 or less). Examples of the soft material include PPO (polyphenylene oxide), TPE (thermoplastic elastomer: for example, TPO (olefin-based thermoplastic elastomer)), PP (polypropylene), PE (polyethylene) and the like. Since the injection molded body 7 formed of such a soft material is easily stretchable, it is difficult to cut it, and it may be difficult to separate it from the residue 8 remaining in the injection flow path 10. The injection molded body 7 here is entirely made of a soft material satisfying the above conditions, but it does not have to be the whole, and at least the portion connected to the residue 8 in the side gate 11 is molded with the soft material. All you need is.

Further, as shown in FIGS. 1 to 5, the injection molding apparatus 100 includes a first extrusion means 4 and a second extrusion means 5. The first extrusion means 4 and the second extrusion means 5 here are provided in the mold 1.

The first extrusion means 4 is included in the cavity 2 here. The first extrusion means 4 cores the injection molded body 7 molded in the molding space 9 from the cavity 2 side in the vicinity of the connecting portion 6 from immediately before the mold opening to the middle of the mold opening shown in FIGS. Extrude to the 3 side. Specifically, the first extrusion means 4 here is a cavity of the first extrusion member 4A inserted into the cavity recess 2H provided in the cavity 2 and opened on the core 3 side, and the first extrusion member 4A thereof. It has a first urging means 4B such as a spring member that urges the core 3 side from the 2 side. The first urging means 4B is housed in the cavity recess 2H, and the first extrusion member 4A can reciprocate in the mold opening direction in a form guided by the inner wall surface of the cavity recess 2H.

The second extrusion means 5 is included in the core 3 here. The second extrusion means 5 shows the residue 8 remaining in the injection flow path 10 including the side gate 11 or the side gate 11 formed so as to be connected to the injection molded body 7 by the connecting portion 6, FIGS. From immediately before the mold opening to the middle of the mold opening shown in (1), it is pushed out from the core 3 side to the cavity 2 side in the vicinity of the connecting portion 6. The second extrusion means 5 urges the second extrusion member 5A inserted into the core recess 3H provided in the core 3 on the cavity 2 side and the second extrusion member 5A from the core 3 side to the cavity 2 side. It has a second urging means 5B such as a spring member. The second urging means 5B is housed in the core recess 3H, and the second extruding member 5A urged by the second urging means 5B opens in a form guided by the inner wall surface of the core recess 3H. It is said that it can move back and forth in the direction.

As shown in FIG. 6, “extruding the injection molded body 7 / residue 8 near the connecting portion 6” means the connecting portion 6 (p3) in the orthogonal direction (horizontal direction in the figure) orthogonal to the mold opening direction. It means that the object is extruded so that the ends 4c and 5c on the connecting portion 6 side of the extruded surfaces 4s and 5s of the extruded members 4A and 5A are located within the range D within 1 mm from the above. By extruding the injection molded body 7 and the residue 8 in the vicinity of the connecting portion 6, the connected injection molded body 7 or the residue 8 is reliably cut at the position of the connecting portion 6 (the tip of the side gate 11). Becomes possible. Since FIG. 6 is a schematic view for explanation as in FIGS. 1 to 5, the dimensions of each part do not correspond to the actual dimensions.

Further, as shown in FIG. 6, the extruded members 4A and 5A here are the ends 4c and 5c of the extruded surfaces 4s and 5s on the connecting portion 6 side in consideration of mutual interference at the time of mold opening. The positions are arranged at positions separated by a predetermined width S (for example, a width defined within 1 mm above) in the orthogonal direction (horizontal direction in FIG. 6). Specifically, the first extruded member 4A here is a region from the position p1 directly above the end 4c to the position p2 on the molding space 9 side (left side in FIG. 6) with respect to the injection molded body 7 in the orthogonal direction. It contacts in 7s and pushes it. On the other hand, the second extrusion member 5A has an injection flow from the position p3 at the end 5c, which is separated from the position p1 on the injection flow path 10 side by a predetermined width S (here, 0.5 mm) with respect to the residue 8 in the orthogonal direction. It abuts in the region 8s over the position p4 on the road 10 side (right side in FIG. 6) and pushes it. The position p3 is located within the above range D.

Further, as shown in FIGS. 1 to 5, the injection molding apparatus 100 regulates the extrusion amount of the first extrusion member 4A, the first extrusion regulating means 2a and 4a, and the extrusion amount of the second extrusion member 5A. It has second extrusion control means 3a and 5a. The first extrusion regulating means 2a and 4a and the second extrusion regulating means 3a and 5a here are provided in the mold 1.

The first extrusion regulating means 2a and 4a project in the orthogonal direction (left-right direction in FIGS. 1 to 4) provided in the first extrusion means 4 (here, the first extrusion member 4A) and orthogonal to the mold opening direction. The first protruding portion 4a and the first locking portion 2a provided in the cavity 2 to which the first protruding portion 4a locks when the cavity 2 is separated from the core 3 by a predetermined distance d at the time of mold opening. Have. Here, the first protruding portion 4a protrudes from the rear end side (upper side of FIGS. 1 to 4) of the first extruded member 4A to the injection flow path 10 side (right side of FIGS. 1 to 4) in the orthogonal direction. do. On the other hand, the first locking portion 2a is an opposing wall facing the first protruding portion 4a at a position separated by a predetermined distance d on the core 3 side in the cavity recess 2H at the time of mold clamping shown in FIGS. 1 and 2. be. With this configuration, the first protruding portion 4a and the first locking portion 2a are locked when the amount of protrusion of the first extrusion member 4A with respect to the cavity 2 toward the core 3 reaches the distance d, and the first extrusion is performed. It restricts the further protrusion of the member 4A and prevents the first extruded member 4A from coming out of the cavity recess 2H.

The second extrusion regulating means 3a and 5a are provided with a second extrusion means 5 (here, a second extrusion member 5A), and a second protrusion 5a protruding in an orthogonal direction orthogonal to the mold opening direction and a core 3 are provided. The second locking portion 3a is provided in the above, and the second protruding portion 5a is locked when the cavity 2 is separated from the core 3 by a predetermined distance d at the time of mold opening. Here, the second protruding portion 5a is from the rear end side (lower side of FIGS. 1 to 5) of the second extruded member 5A to the molding space 9 side (in the orthogonal direction) opposite to the first protruding portion 4a (the lower side of FIGS. 1 to 5). It protrudes to the left side of FIGS. 1 to 5). On the other hand, the second locking portion 3a is an opposing wall facing the core recess 3H at a position separated by a predetermined distance d from the second protruding portion 5a at the time of mold clamping shown in FIGS. 1 and 2. be. With this configuration, the second protruding portion 5a and the second locking portion 3a are locked when the amount of protrusion of the second extrusion member 5A with respect to the core 3 toward the cavity 2 reaches the distance d, and the second extrusion is performed. It restricts further protrusion of the member 5A and prevents the second extruded member 5A from coming out of the core recess 3H.

Here, the flow of opening the mold 1 will be described. 1 to 5 show a cross section of a mold 1 of an injection molding apparatus 100, from a mold-clamped state before the molten material is injected (see FIG. 1), and then the molten material is injected and cooled and solidified. The state (see FIG. 2), each state when the mold opening is executed (see FIGS. 3 and 4), and the state when the product is ejected (see FIG. 5) are shown in order.

In the mold clamping state, as shown in FIG. 1, the cavity 2 including the first extrusion member 4A and the core 3 including the second extrusion member 5A face each other, and the molding space 9 and the injection flow path are opposed to each other. 10 is formed. At this time, the first extruded member 4A is in contact with the core 3 at a position not shown in FIG. 1 while forming a molding space 9 with the core 3, and the first urging means 4B is in contact with the core 3 at the contacting position. It is pressed against the core 3. On the other hand, the second extrusion member 5A also forms an injection flow path 10 with the cavity 2 and is in contact with the cavity 2 at a position not shown in FIG. 1, and the second urging means is in contact with the cavity 2. Pressed by 5B.

When the molding space 9 and the injection flow path 10 are formed by molding, the molten material to be a soft material is injected from the injection nozzle described above. The molten material flows into the molding space 9 through the injection flow path 10. After that, as shown in FIG. 2, the injection molded body 7 is formed in the molding space 9 by the molten resin cooled and solidified, and the residue 8 in a state of being connected to the injection molded body 7 in the injection flow path 10. Is formed.

After that, the mold opening is executed. When the mold opening starts, as shown in FIGS. 2 to 4, the first extrusion means 4 extrudes the injection molded body 7 from the cavity 2 side to the core 3 side in the vicinity of the connection portion 6, and the second extrusion means 5 remains. The body 8 is pushed out from the core 3 side to the cavity 2 side in the vicinity of the connecting portion 6. As a result, as shown in FIG. 3, the injection-molded article 7 and the residue 8 are cut and separated at the connecting portion.

Specifically, immediately after the start of mold opening, as shown in FIG. 2, the first extrusion means 4 brings the first extrusion member 4A into contact with the core 3 by the urging force of the first urging means 4B (FIG. The second extrusion means 5 keeps the second extrusion member 5A in contact with the cavity 2 (at a position not shown in the figure) by the urging force of the second urging means 5B. (Abutment). These contact states continue until the separation distance between the cavity 2 and the core 3 after the mold opening reaches a predetermined distance d (see FIG. 3). On the other hand, in the injection molded body 7 and the residual body 8 connected by the connecting portion 6, the injection molded body 7 side faces the first extruded member 4A on the core 3 immediately after the mold opening shown in FIG. 2 starts. Although held between them, the residue 8 side is extruded to the cavity 2 side (upper side in FIG. 2) by the second extrusion member 5A. As a result, the injection molded body 7 side is also extruded to the cavity 2 side (upper side in FIG. 2). However, the injection molded body 7 side is received by the first extrusion member 4A. It can be said that this received state is a state in which the injection molded body 7 side is extruded to the core 3 side (lower side in FIG. 2) by the first extrusion member 4A. That is, immediately after the start of mold opening, the connecting portion between the injection molded body 7 and the residual body 8 is extruded to the upper side of FIG. 2 on the residual body 8 side, and at the same time, is extruded to the lower side of FIG. 2 on the injection molded body 7 side. As a result, shearing force acts. By this shearing force, as shown in FIG. 3, the injection-molded article 7 and the residue 8 are cut at their connecting portions and separated.

When the mold opening further progresses and the cavity 2 is separated from the core 3 by a predetermined distance d or more, the first protruding portion 4a and the first locking portion 2a are locked and the first extruded member is engaged as shown in FIG. Further protrusion of 4A is restricted, and further protrusion of the second extruded member 5A is restricted by locking the second protruding portion 5a and the second locking portion 3a. As a result, the contact state between the first extrusion member 4A and the core 3 (contact at a position not shown in the figure) and the contact state between the second extrusion member 5A and the cavity 2 (contact at a position not shown in the figure). Contact) is resolved. The cavity 2 is completely separated from the injection molded body 7 including the first extruded member 4A, and the injection molded body 7 remains on the core 3.

At this time, as shown in FIG. 4, the residue 8 separated from the injection molded body 7 is separated from the core 3 (including the second extrusion member 5A) and recovered in the injection molding apparatus 100.

After that, as shown in FIG. 5, the protruding member 30 on the core 3 side protrudes the injection molded body 7, the injection molded body 7 is detached from the core 3, and is collected by the injection molding device 100.

As described above, according to the injection molding apparatus 100 of the present embodiment, when the mold is opened, the injection molded body 7 and the residue 8 can be cut at a portion connecting them, and a gate cut can be performed to surely separate the two. become.

The side gate 11 has a shape that tapers toward the molding space 9 side. Therefore, the tip portion 5b of the second extrusion member 5A on the molding space 9 side has a wedge shape (triangular shape) located on the cavity 2 side so that the tip surface 5s on the cavity 2 side faces the molding space 9 side. The shape is suitable for cutting the injection-molded body 7 and the residue 8 when the mold is opened (a shape in which a wedge is driven at the connecting portion 6).

Further, in the injection molded body 7 thus molded by the injection molding apparatus 100 of the present embodiment, as shown in FIG. 7, the first extrusion means 4 (the first extrusion means 4 (the first) is formed on the main surface 7s on the cavity 2 side at the time of molding. It has a pressing mark 7t pressed against the extruded member 4A). The pressing mark 7t here is a mark on which the end 4d (see FIG. 6) of the extruded surface 4s of the first extruded member 4A is pressed. Further, the side gate 7u has a gate mark 7g of the side gate 11 when the main surface 7s is the upper surface. Here, as shown in FIG. 7, since the side gate 11 is connected to the protruding tip surface (side surface 7u) of the plate-shaped protruding portion 7Q of the injection molded body 7, the gate mark 7g is formed on the protruding tip surface (7u). A pressing mark 7t remains on the upper surface (main surface 7s) adjacent to the protruding tip surface (7u) with a corner in between. On the other hand, the residue 8 also has a pressing mark 8t pressed against the second extrusion means 5 (second extrusion member 5A) on the main surface on the core 3 side at the time of molding. The pressing marks 8t here are two, a mark pressed against the end 5c on the connecting portion 6 side of the extruded surface 5s of the second extrusion member 5A, and a mark pressed against the end 5d on the opposite side.

Although one embodiment of the present invention has been described above, this is merely an example, and the present invention is not limited thereto. For example, various changes can be made based on the knowledge of those skilled in the art, such as omitting some of the constituent requirements in the first embodiment and adding other constituent requirements.

Hereinafter, other examples and modifications of the present invention will be described. The same functional parts as those in the above embodiment and similar functional parts will be designated by the same reference numerals, and detailed description thereof will be omitted. In addition, the above-mentioned example and the following examples and modifications can be appropriately combined and carried out within a range that does not cause a technical contradiction.

For example, in the above embodiment, the side gate 11 has a shape that tapers toward the molding space 9 side (connecting portion 6) (see FIG. 2). Therefore, the second extrusion member 5A has a wedge-shaped (triangular) tip portion 5b located on the cavity 2 side so that the tip surface 5s facing the cavity 2 faces the molding space 9 side (FIG. 6). 6), the cavity 2 is provided with a wedge-shaped (triangular) tip portion that is located on the second extrusion member 5A side so that the surface of the second extrusion member 5A facing the tip portion 5b faces the molding space 9 side. It may be provided. Further, both the tip portion 5b of the second extrusion member 5A and the tip portion of the cavity 2 facing the tip portion 5b may have a wedge shape (triangular shape) as described above.

100 Injection molding device 1 Mold 2 Cavity 3 Core 4 First extrusion means 5 Second extrusion means 6 Connection part 7 Injection molding 7g Gate mark 7t Pressing mark 8 Residue 8t Pressing mark 9 Molding space 10 Injection flow path 11 Side gate

Claims (6)

A mold in which a molding space and a side gate for injecting a soft material having a shore A hardness of 90 or less into the molding space are formed between the molded core and the cavity facing each other.
A first extrusion means for extruding an injection molded product molded in the molding space toward the core near the connection portion between the molding space and the side gate when the mold is opened.
A second extrusion that is formed so as to be connected to the injection molded body and that extrudes the residue remaining in the side gate or the injection flow path including the side gate toward the cavity side in the vicinity of the connection portion at the time of the mold opening. Means and
A gate cutting method characterized in that, at the time of opening the mold, the injection molded product and the residue are cut and separated at their connecting portions by the first extrusion means and the second extrusion means. .. The gate cutting method according to claim 1, wherein the side gate has a shape that tapers toward the molding space side. The gate cutting method according to claim 1 or 2, wherein the first extrusion means and the second extrusion means are provided in the mold. A mold used in the gate cutting method according to claim 3. An injection molding apparatus including the mold, the first extrusion means, and the second extrusion means used in the gate cutting method according to any one of claims 1 to 3. An injection-molded article of a soft material having a shore A hardness of 90 or less, which is molded by the gate cutting method according to any one of claims 1 to 3, and is mainly on the cavity side at the time of molding. An injection-molded article having a pressing mark pressed against the first extrusion means on the surface.

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