JP7514670B2 - Molding die components - Google Patents

Description

The present invention relates to a molding die component for molding, for example, a heated and melted synthetic resin container lid.

Conventionally, synthetic resin container lids made of synthetic resin materials such as polyethylene or polypropylene are known and are used, for example, for sealing containers. Such synthetic resin container lids are generally mass-produced using molding dies used for injection molding, compression molding, etc., as shown in, for example, Patent Document 1.

The molds used in this type of molding are generally manufactured by cutting, but in recent years, it has also been proposed to manufacture molds by three-dimensional modeling using so-called 3D printers.

For example, Patent Document 2 proposes that by using 3D modeling of a metal mold using metal powder to simultaneously form a temperature control circuit when the mold is molded using laser light, machining constraints are eliminated and the degree of freedom in designing the temperature control circuit is improved compared to conventional metal molds in which a temperature control circuit is created by machining after the mold is molded.

Furthermore, for example, Patent Document 3 proposes that when manufacturing a resin mold for three-dimensionally molding a photocurable resin using a three-dimensional printing device, the cooling pipe through which the cooling medium for cooling the mold flows is bent along the contact surface where the molded product comes into contact with the mold, and that 60% or more of the area of the contact surface is set within 8 mm of the cooling pipe.

Japanese Patent Application Laid-Open No. 1-235615 Japanese Utility Model Application Publication No. 11-348045 JP 2017-124592 A

Indeed, by using the above-mentioned three-dimensional printing equipment to manufacture the molding die as a single unit, it is possible to simultaneously manufacture cooling channels and the like in accordance with the shape of the molded product.
When the synthetic resin container lid is screwed onto the mouth of the container, a screw thread is formed on the inside of the skirt wall. Here, the diameter of the container lid is about 20 to 30 mm, and the screw thread is relatively small. However, if the heat is removed too much after molding, the molded product will be damaged when released from the mold, and if the heat is not removed enough, the molded product will be deformed.

In other words, in molding dies for molding synthetic resin container lids, proper heat removal from the molded product is important, but the conventional technologies, including the patent documents mentioned above, have not addressed the issues described below, and it is difficult to say that they still meet market needs.
SUMMARY OF THE PRESENT EMBODIMENTS Accordingly, one object of the present invention is to provide a molding die component capable of properly removing heat from a molded product in a molding die for molding a synthetic resin container lid.

In order to solve the above problems, one embodiment of the present invention provides a molding die part (1) that is a molding die member for use in a molding die, comprising a male die and a female die that are 3D-molded as a single unit by sintering metal powder with laser light, and into which molten resin flows to form a sealing body that seals a container by forming a thread, the molding die part having a thread groove convex portion for forming the thread of the sealing body, formed on one of the male die or the female die, and a cooling flow path portion that is disposed inside the thread groove convex portion and through which a cooling medium flows to cool the sealing body in opposing directions along the flanks of the thread, the cooling flow path portion being a spiral flow path that does not branch out from an inlet port through which the cooling medium that cools the molten resin flows in to an outlet port from which the cooling medium is discharged .
In order to solve the above-mentioned problems, a molding die part in one embodiment of the present invention is (2) a molding die member for use in a molding die comprising a male die and a female die which are 3D-molded integrally by sintering metal powder with laser light, and into which molten resin flows to form a sealing body which seals a container by forming a thread, the molding die part having a thread groove convex portion formed in one of the male die and the female die, and a cooling flow path portion through which the cooling medium flows in such a manner that the cooling medium flows in an inlet port for cooling the molten resin and an outlet port disposed inside the thread groove convex portion, the cooling flow path portion being opposed along the flanks of the thread, the cooling flow path portion being arranged so that at least a portion of the cooling flow path portion is accommodated in the thread groove between the threads which are adjacent to each other in the vertical axial direction in the sealing body to be molded.

In the molding die parts described in (1) or (2) above, ( 3 ) it is preferable that the cooling flow passage portion is formed so as to be continuous in the circumferential direction along the flank and continuous in the up-down axial direction of the thread.

In addition, in any of the molding die parts described in (1) to (3) above, (4) the sealing body is a cap that screws onto the mouth of the container, and the male mold defines the inner surface of the top wall of the cap, the inner surface of the skirt wall that hangs down from the top wall, and the thread formed on the inner surface of the skirt wall, and the female mold defines the outer surface of the top wall and the outer surface of the skirt wall.

The present invention makes it possible to realize a molding die part that can prevent damage or deformation of a synthetic resin container lid caused by improper heat removal.

FIG. 2 is a front view showing the appearance of the molding die part according to the embodiment. FIG. 2 is an external perspective view of a molding die part according to the embodiment. FIG. 2 is a cross-sectional view (part 1) showing a structure of a refrigerant flow path in a molding die part according to an embodiment. FIG. 2 is a cross-sectional view (part 2) showing the structure of a refrigerant flow path in a molding die component according to an embodiment. 1A to 1C are schematic diagrams illustrating a molding die including a molding die part according to an embodiment and a molded product. FIG. 1 is a schematic diagram showing a molding die having a conventional structure as a comparative example.

The following describes an embodiment for implementing the present invention. In this embodiment, for the sake of convenience, the X, Y, and Z directions are appropriately set in the explanation using the figures, but this is for the sake of convenience and does not excessively limit the present invention. In addition, for mechanisms other than the configurations described in detail below, the structure of a molding die used for known synthetic resin container lids, including those described in Patent Document 1 above, may be appropriately applied.

[Molding die 1000]
First, as shown in Figure 5 and other figures, the molding die 1000 in this embodiment is composed of a male LDM (core) and a female UDM (cavity) that are 3D shaped integrally by sintering metal powder with laser light.

Molten resin flows into the molding die 1000 through the runner RN and gate GT in the molding die 1000 to form a sealing body CAP that forms a screw thread 3 and seals a container (not shown). As an example, in this embodiment, molten resin heated to about 150°C to 200°C is injected into the molding die 1000 and cooled by a known refrigerant (such as water) at about 10°C to 30°C.

The resin material that can be used in this embodiment is not particularly limited as long as it is a meltable resin used in injection molding or compression molding, and known synthetic resin materials such as polypropylene and polyethylene can be used. Also, in this embodiment, injection molding is described as an example of the application of a molding die, but the present invention can also be applied to other molding methods such as the above-mentioned compression molding and extrusion molding.

More specifically, the molding die 1000 in this embodiment is configured to include a molding die part 100 as a screw core that is inserted inside the molded product (sealing body CAP), a cavity 200 that contacts the outside of the top wall and skirt wall of the molded product (sealing body CAP), a stripper bushing 300 that is used when performing so-called forced removal, a cooling core 400 in which one of the refrigerant flow paths CW is formed, and a cooling bar 500 that is inserted into the cooling core 400 to control the flow of the refrigerant.

[Molding die part 100]
As shown in Figures 1 to 4, the molding die part 100 of this embodiment can be incorporated into the above-mentioned molding die 1000, and is configured to include a thread groove protrusion 10, a thread groove portion 11, an interrupted wall 12, a TE forming portion 13, an end forming portion 14, and a cooling flow path portion 20.
The molding die component 100 of this embodiment is integrally manufactured using the above-mentioned known three-dimensional modeling device such as a so-called 3D printer. There is no particular limitation on the material of the molding die component 100 of this embodiment, and various known metal powders capable of three-dimensional modeling can be used.

The thread groove protrusion 10 is used to form the thread 3 of the sealing body CAP described above. The thread groove can be formed in either the male or female mold depending on the shape of the sealing body CAP. Therefore, the thread groove protrusion 10 of this embodiment is formed in either the male or female mold corresponding to the above. The thread groove protrusion 10 forms a thread groove in the sealing body CAP after molding.

In this embodiment, the sealing member CAP is preferably a synthetic resin cap that is screwed onto the mouth of a known container such as a PET bottle. However, the sealing member CAP suitable for this invention is not limited to the container lid (cap) described above as long as it has a screw structure, and may be other known sealing members with a screw structure, such as a spout.

In this embodiment, the sealing body CAP is a cap that screws onto the mouth of the container as described above (see also FIG. 5(b) as appropriate), and the male LDM described above defines the inner surface of the top wall 1 of the cap, the inner surface of the skirt wall 2 that hangs down from the top wall 1, and the thread 3 formed on the inner surface of the skirt wall 2. Similarly, as shown in the same figure, the outer surface of the top wall 1 and the outer surface of the skirt wall 2 are each defined by the female UDM described above.

As can be seen from Figures 1 and 2, the thread grooves 11 are arranged above and below the thread groove protrusions 10 in the vertical axial direction (Z direction) so that a helical thread 3 is formed in the sealing body CAP after molding.

The interrupted walls 12 are arranged at a predetermined interval in the circumferential direction so that the threads 3 and thread grooves of the sealing body CAP described above are interrupted along the circumferential direction (θz direction). Note that when the threads 3 of the sealing body CAP are made to be a continuous spiral, such interrupted walls 12 are omitted.

The TE forming portion 13 is a groove portion for forming a tamper evident in the molded sealed body CAP, which indicates that the sealed body CAP has been opened. There are no particular limitations on the structure of such a tamper evident, and any known tamper evident structure can be applied.

The end forming portion 14 is the portion where the lower end of the sealing body CAP will be located after molding. In the molding die part 100 of this embodiment, as an example, the lower side of the end forming portion 14 is tapered with a gradually expanding diameter.

The cooling flow passage portion 20 is disposed inside the thread groove protrusion portion 10, and a cooling medium flows in a manner to face the flank f of the thread 3 of the sealing body CAP molded along the flank f of the thread 3 of the CAP shown in FIG. 5(b). Note that the cooling medium in this embodiment can be a known liquid or gas, such as water whose temperature has been adjusted as described above.

5, the cooling channel portion 20 of this embodiment is composed of three cooling channels, a first cooling channel _CW1 , a second cooling channel _CW2 , and a third cooling channel _CW3 . Among these, the first cooling channel _CW1 is disposed on the side of the above-mentioned cavity 200, and is responsible for cooling the molten resin toward the outer circumferential surface of the skirt wall 2 of the sealing body CAP.

In addition, the second cooling flow passage _CW2 constituting the cooling flow passage portion 20 of this embodiment is arranged inside the above-mentioned thread groove convex portion 10, and the cooling medium flows along and facing the flank f of the thread 3 of the molding sealing body CAP.
The remaining third cooling flow path _CW3 constituting the cooling flow path section 20 is disposed within the above-mentioned cooling core 400, and is responsible for cooling the molten resin toward the inside of the skirt wall 2 of the sealing body CAP (for example, the inner ring 4, the outer ring 5, or the inner surface of the top wall 1, etc.).

In this embodiment, the cooling flow path section 20 is configured by a total of three cooling flow paths as described above, but is not limited to this example and may be configured as a single flow path or may be configured by two or four or more flow paths as long as at least the second cooling flow path _CW2 is provided.

As can be seen from Figures 3 and 4, the cooling channel section 20 in this embodiment is preferably formed so as to be continuous in the circumferential direction along the inclined surface (flank f) of the thread 3 of the sealing body CAP described above, and to be continuous in the up and down axial direction (Z direction in the figure) of this thread 3. This allows the cooling channel section 20 to be arranged close to the flank f of the thread 3, which is difficult to remove heat properly, and the necessary and sufficient heat removal from the molten resin after molding can be achieved.

5A, at least the second cooling flow passage _CW2 of the cooling flow passage portion 20 of this embodiment preferably has a spiral flow passage that does not branch from an inlet port _CW2IN into which a cooling medium (such as cooling water) for cooling the molten resin flows to an outlet port _CW2OUT from which the cooling medium is discharged, thereby making it possible to efficiently and appropriately remove heat from the sealing body CAP without complicating the device configuration.

3 and 4, it is preferable that the cooling channel portion 20 (second cooling channel _CW2 ) of this embodiment is provided so that at least a part of it is accommodated in the thread groove between adjacent threads 3 in the vertical axial direction of the sealing body CAP (Z direction in the figures) from the viewpoint of the sealing body CAP to be molded. This makes it possible to efficiently assign one cooling channel to the flanks f of both adjacent threads 3.

As shown in Fig. 4, in this embodiment, the distance R3 from the bottom of the thread groove 11 (the portion that becomes the top of the thread 3 of the sealing body CAP) to the central axis O is greater than the distance R1 to the central axis O of the coolant flow passage located on the outermost side of the second cooling passage _CW2 . However, this embodiment is not limited to the above, and for example, R1 = R3 or R1 > R3 may be set. In this case, when R1 ≥ R3, the thread 3 of the sealing body CAP (particularly the flank f portion) can be cooled more efficiently.

<Advantages over conventional mold structures>
As described above, although the technology of three-dimensional molding using metal powder or resin powder is known, in the field of manufacturing sealing bodies CAP, molding dies formed by cutting/grinding processes are often used as shown in Fig. 6. In this case, for example, when the sealing body CAP is a cap or a spout, the flow path arranged in the die is relatively small, so that the molded part is processed by multiple pieces such as two pieces.

Because molded parts are thus made up of multiple pieces, special packing P (see Figure 6 for an example) is required, particularly to prevent leakage from the refrigerant flow paths. However, as mentioned above, the diameter of the flow paths arranged inside the mold is small, so such packing must also be custom-made, resulting in increased costs.

As can be seen from Figure 6, in the past, it was not easy to place the refrigerant flow path close to the thread 3 of the sealing body CAP in order to maintain the strength of the mold, and it had to be placed at a position relatively far away from the top of the thread 3. Therefore, compared to the molding mold 1000 of this embodiment (see Figure 5), the temperature of the molten resin had to be controlled by the cooling medium from a position far away from the thread 3, and it could not be said that cooling was sufficient, especially up to the flank f of the thread 3.

In contrast, the molding die part 100 of this embodiment has a cooling flow passage section 20 that is arranged inside the thread groove protrusion 10 and through which a cooling medium flows to cool the thread 3 in an opposing manner along the flank f of the thread 3. This makes it possible for the molten resin injected into this molding die to maintain a degree of elasticity sufficient to withstand the above-mentioned forced removal, while also suppressing deformation caused by insufficient heat removal.

In other words, in the field of molding the encapsulated body CAP, strict temperature control is required where neither overcooling nor insufficient cooling is permitted, but according to this embodiment, it is possible to realize a molding die part that can suppress damage and deformation of the synthetic resin container lid caused by improper heat removal. Furthermore, according to this embodiment, as described above, since it is possible to perform integral molding using three-dimensional modeling technology, it is possible to reduce the cost required for mold manufacturing and also eliminate the need for expensive packing to prevent leakage.

The above embodiment is a suitable example for implementing the present invention, and the elements of the embodiment may be modified or combined as appropriate to form a new molding die or molding die part without departing from the spirit of the present application.

4, the distances R from the central axis O of the cooling flow passage sections 20 (second cooling flow passages CW ₂ ) arranged along the vertical axial direction (Z direction) are uniform in this embodiment, but may be different from each other. More specifically, for example, the distance R2 from the central axis O of the cooling flow passage section 20 on the side relatively closer to the top wall 1 of the sealing body CAP may be set to be greater than the distance R1 from the central axis O of the cooling flow passage section 20 on the side relatively farther from the top wall 1.

Also, as shown in the figure, the hole diameters of the cooling flow passage sections 20 (second cooling flow passages CW ₂ ) arranged along the vertical axial direction (Z direction) are uniform in this embodiment, but may be different from each other. More specifically, for example, the hole diameter (diameter) of the cooling flow passage section 20 on the side relatively closer to the top wall 1 of the sealing body CAP may be set larger than the hole diameter (diameter) of the cooling flow passage section 20 on the side relatively farther from the top wall 1. This can further improve the cooling efficiency in the portion of the sealing body CAP that becomes the top wall 1.

As shown in the figure, the shape of each of the cooling flow passage sections 20 (second cooling flow passages _CW2 ) arranged along the up-down axial direction (Z direction) is a uniform round hole along the circumferential direction in this embodiment, but the cooling flow passage section 20 may have a circular or non-circular cross-sectional shape. Furthermore, the shape of the spiral flow passage in this second cooling flow passage _CW2 may be different depending on the circumferential position (for example, the cross-sectional shape of a part of the flow passage in the circumferential direction is circular and the other part is rectangular).

In the present embodiment, the cooling flow passage portion 20 (the second cooling flow passage CW ₂ ) is a spiral flow passage that does not branch from the inlet port CW _{2 IN} to the outlet port CW _{2 OUT} , but it does not necessarily have to be spiral. That is, for example, a plurality of annular cooling flow passages may be provided corresponding to the threads 3 of the sealing body CAP, and a communication flow passage may be further formed along the vertical axial direction that connects adjacent annular cooling flow passages in the vertical axial direction (Z direction). Also, this second cooling flow passage CW ₂ does not necessarily have to be a single flow passage that does not branch, and for example, a plurality of annular cooling flow passages may be provided independently of each other corresponding to the threads 3 of the sealing body CAP.

The present invention is suitable for providing molding die parts that have excellent heat removal properties in molding dies that mold molded products with threads.

1000: Molding die 100: Part for molding die 10: Thread groove convex portion 11: Thread groove portion 12: Intermittent wall 13: TE forming portion 14: End forming portion 20: Cooling flow passage portion CW ₁ : First cooling flow passage CW ₂ : Second cooling flow passage CW ₃ : Third cooling flow passage 200: Cavity 300: Stripper bushing 400: Cooling core 500: Cooling bar

Claims (4)

A molding die member for use in a molding die, which comprises a male die and a female die that are integrally 3D-modeled by sintering metal powder with a laser beam, and into which a molten resin is poured to form a sealing body that seals a container by forming a screw thread,
A thread groove protrusion for forming a thread of the sealing body, which is formed on either the male mold or the female mold;
A cooling flow passage portion is provided inside the thread groove convex portion, and a cooling medium flows through the cooling flow passage portion so as to face the flank of the thread ,
A molding die member, characterized in that the cooling flow path portion is a spiral flow path that does not branch out from an inlet port through which a cooling medium for cooling the molten resin flows to an outlet port through which the cooling medium is discharged . A molding die member for use in a molding die, which comprises a male die and a female die that are integrally 3D-modeled by sintering metal powder with a laser beam, and into which a molten resin is poured to form a sealing body that seals a container by forming a screw thread,
A thread groove protrusion for forming a thread of the sealing body, which is formed on either the male mold or the female mold;
a cooling flow passage portion through which the cooling medium flows for cooling the molten resin in an opposite direction along the flank of the thread, the cooling flow passage portion being provided inside the thread groove convex portion and including an inlet port into which a cooling medium for cooling the molten resin flows and an outlet port through which the cooling medium is discharged,
A molding die member, characterized in that the cooling flow path portion is arranged so that at least a portion of the cooling flow path portion is accommodated within a thread groove between adjacent threads in the vertical axial direction in the molding of the sealing body . 3. The molding die member according to claim 1 , wherein the cooling flow passage portion is formed so as to be continuous in a circumferential direction along the flank and to be continuous in an up-down axial direction of the thread. The sealing body is a cap that screws onto the mouth of the container,
The male mold defines an inner surface of a top wall of the cap, an inner surface of a skirt wall that hangs down from the top wall, and the thread formed on the inner surface of the skirt wall,
The molding die member according to any one of claims 1 to 3, wherein an outer surface of the top wall and an outer surface of the skirt wall are each defined by the female mold.