JP2584953B2 - Runnerless mold for injection molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold used for injection molding, and more particularly, to a sprue or a sprue provided with a heating means for constantly heating a runner immediately before a gate opening to a carved portion during the molding operation. The present invention relates to a runnerless mold for injection molding for use in an injection molding machine for injection molding a target resin product without removing a runner such as a runner as a molded product.

[0002]

2. Description of the Related Art In a runnerless mold, a runner such as a sprue or a runner is not taken out as a molded product. Therefore, it is necessary to perform post-finishing such as a runner removing operation for removing the sprue or the runner from the molded product after molding. Because there is no
It has the advantages that its productivity is high and that it is possible to automate the process from molding to packaging of the product, and that there is no loss of raw material resin and the molding cycle can be shortened.

However, in such a runnerless mold, it is necessary to constantly heat the runner immediately before the gate opening to the engraved portion during the molding operation to keep the resin supplied from the gate to the engraved portion in a molten state. Therefore, it is necessary to incorporate a heating means into the mold, and the mold structure, particularly the structure on the fixed side, is necessarily complicated, and the production cost of the mold is extremely high. In addition, in this runnerless mold, the mold itself becomes large and its weight increases. For example, in a case where 20 ice cream spoons are taken, the weight reaches approximately 1.2 tons. In order to control temperature and operation, it is necessary to connect with a very large number of wires and pipes to peripheral devices such as temperature control devices and hydraulic devices. There is also a problem that a great deal of labor and time of several tens of hours are required in some cases.

However, in recent years, as demand for instant foods, ice creams and the like has increased, packaging, knives, forks, spoons and the like used for these instant foods, ice creams and the like have also been used, consumers and traders. Preferences have diversified, and for that,
It is necessary to manufacture not only the same size and the same shape but also molded products with different shapes and sizes according to applications and preferences. There is a need.

However, as described above, the runnerless mold has many advantages such as productivity, automation, no loss of raw material resin, and shortening of the molding cycle. The manufacturing cost is high, and a large amount of labor and time is required for the mold changing operation. Thus, it has been said that such a method is not suitable for manufacturing a relatively small number of resin molded products with a relatively small number.

[0006]

Therefore, the present inventor has proposed:
As a result of intensive studies on the improvement of the runnerless mold to solve such problems, most of the fixed side of the runnerless mold, including the gate that opens to the engraved part on the fixed side, is the main fixed side. As a common part, a large part of the fixed side carved portion formed on this fixed side is detachably formed on the main fixed side as a divided fixed side,
As a result, a runnerless metal mold that can cope by changing only the divided fixed side and the movable side when the item of the resin molded product to be manufactured and its size and shape are changed has been completed, and has reached the present invention.

Accordingly, it is an object of the present invention to provide a runnerless mold which is excellent in productivity and can easily cope with automation of a production line, has no loss of raw material resin, and can shorten a molding cycle. Runnerless for injection molding, which is suitable for producing many types of resin molded products while keeping the advantages and at the same time minimizing the production cost of the mold, and which facilitates the mold replacement work. To provide a mold.

[0008]

That is, the present invention relates to a runner which is fixed to a fixed die plate of an injection molding machine and through which a molten resin introduced from an injection device flows, and a gate provided at the end of the runner. And a fixed side having a heating means for constantly heating the runner immediately before the gate during the molding operation, a movable side attached to a movable die plate of an injection molding machine, and a fixed side and a movable side. In a runnerless mold for injection molding having an engraved portion formed between the gate and filling the molten resin from the gate at the time of molding, the fixed-side engraved portion formed on the fixed side has a shape of a plurality of types of molded products. A common part area for molding a small common part of substantially the same shape designed from the above and a main part area for molding the main part of the molded article occupying most of the molded article are provided, and the common part area of the fixed side engraving part is provided. The gate of the above-mentioned runner is opened at the fixed side, and the portion forming the main portion area of the fixed side carved portion on the fixed side is regarded as an island-shaped independent divided fixed side, and the divided fixed side from the main fixed side of other main portions is mainly It is divided so that it can be detachably attached to the mounting recess formed on the fixed side, while the movable side engraved part formed on the movable side has a common part corresponding to the common part area of the fixed side engraved part and the main part area An area and a main part area are provided, and the part forming the main part area of the moving side engraving part corresponding to at least the main part area of the fixed side engraving part on the moving side is regarded as an island-shaped independent divided moving side and other main parts are formed. The main moving side is divided so that the divided moving side can be detachably attached to a mounting recess formed on the main moving side, and the divided fixed side and the moving side are exchanged with the main fixed side. A runnerless mold for injection molding, characterized in that the replaceable the divided movable relative to the main movable together allows.

In the present invention, the common portion region formed in the engraved portion on the fixed side of the runnerless mold occupies a relatively small portion of a molded product formed by using the runnerless mold. When the divided fixed side and the movable side are exchanged for different ones, and another type of molded article is formed in terms of the item, size or shape, at least this fixed The part formed by the common part area on the side is molded as a molded part common part of substantially the same shape and size that completely matches.

Therefore, the common portion area of the fixed side engraved portion determines a molded product common portion having substantially the same shape and size from the shapes of a plurality of types of molded products to be manufactured. It is designed based on size, and it is better to design it as small as possible in order to give individuality to the shape and size of each of a plurality of types of molded products to be manufactured. When the molded product to be used is a knife, a fork, and a spoon, it is preferable that the tip portion of the handle be a molded product common portion formed in the common portion region. Then, in the fixed side engraved portion, a portion other than the molded product common portion, that is, a portion for molding the molded product main portion occupying most of the molded product is a main portion region other than the common portion region, for example, In the example of the knife, fork and spoon, it is an area for molding all parts other than the tip part of the handle.

Further, in the present invention, a gate of a molten resin runner is opened in a common portion area of the fixed side carved portion, and a portion forming a main portion region of the fixed side carved portion on the fixed side is provided. As a division fixed side, it is detachably divided from the main fixed side of other main parts. The divided fixed side divided from the main fixed side constitutes a predetermined part (island part) of the entire fixed side mold plate (sea part) (in an island shape).
It is composed of an independent mold and is detachably and removably mounted in a mounting recess formed at a predetermined position on the main fixed side.

When the fixed side is divided into the main fixed side and the divided fixed side, the common portion area of the fixed side carved portion is on the main fixed side, and the main portion region of the fixed side carved portion is divided on the divided fixed side. , And is not particularly limited by the arrangement of the runner, but in order to achieve the object of the present invention, it is preferable to share as many parts as possible on the fixed side, and The fixed side is preferably designed so that its volume is reduced as much as possible in consideration of its strength and rigidity. Here, if the main fixed side is formed of a relatively hard high-quality material such as Swedish steel, and the divided fixed side is formed of a relatively soft and inexpensive steel material that is easy to machine, damage to the main fixed side is minimized. In addition, it is possible to manufacture the divided fixed side at lower cost.

On the other hand, in the present invention, a movable side engraving portion is provided on the moving side, which is composed of a common portion region and a main portion region corresponding to the common portion region and the main portion region of the fixed side engraving portion. In other words, the movable side engraved portion is opposed to the fixed side engraved portion by closing the mold, thereby forming the engraved portion of the runnerless mold filled with the molten resin at the time of molding. Further, a portion forming the main portion area of the engraving portion on the moving side on the moving side is removably divided from the main moving side of the other main portions as a split moving side. The divided moving side is formed of a mold independent in the form of an island with respect to the entire mold on the moving side, and is formed at a predetermined position on the main moving side in substantially the same manner as the divided fixed side. It is detachably attached to the attachment recess so that the position can be adjusted. In addition, on the divided moving side, the shape on the moving side of the common portion area may be slightly changed in shape or size depending on the type of the molded article to be molded. In general, it is desirable to form both the main region and the common region of the engraving portion on the moving side from the viewpoint of, for example, the necessity of keeping the parting line out as much as possible. However, in the present invention, only the main portion region may be formed on the divided moving side, and in this case, the common portion region is formed on the main moving side.

In the present invention, although not particularly limited, a heating means for constantly heating the runner immediately before the gate during the molding operation, and a hydraulic device for operating the valve gate type in the case of the valve gate type. In the case of a hot chip gate, relatively expensive parts such as the chip heating means are preferably provided on the main fixed side as much as possible and shared, and more preferably connected to the injection device. A sprue bushing, a manifold connected to the sprue bushing, a nozzle connected to the manifold, a heater for heating the sprue bushing, a manifold, a nozzle, and the like are incorporated in the main fixed side to be shared and a split fixed side. For the main part of the engraved part only, or in addition to this, a flat plate having part or all of the cooling water hole Formed in, whereby it is possible to greatly reduce the manufacturing cost of the split stationary. In addition,
The cooling water hole formed on the fixed side does not necessarily need to be located only on the main fixed side, and may be formed so as to extend from this main fixed side to the divided fixed side. Separate cooling water holes may be provided on the divided and fixed side.

The present invention is applicable to any type of mold if it is a runnerless mold.
Applicable to single-cavity molds, multi-cavity molds such as 2-cavity and 3-cavity molds, and multi-cavity molds such as 10-cavity molds and 20-cavity molds In addition to this, the present invention can be applied irrespective of a gate method such as a valve gate method or a hot chip gate method.

A runnerless mold according to the present invention is a multi-cavity mold having a plurality of runners and gates formed on a fixed side thereof and a plurality of engraved portions between a solid side and a movable side. In some cases, it is preferable to arrange the common portion areas of the fixed side engraved portions formed on the fixed side close to each other and to arrange them in a predetermined partitioned area, and position this partitioned area on the main fixed side. As for the divided area where the common area is disposed, gates for the runners are opened in the respective common areas on the fixed side. Therefore, the arrangement of the molten resin runners reaching these gates should be considered. For example, it is possible to design a relatively wide rectangular shape in which each gate is arranged in two horizontal rows, a circular shape in which each gate is arranged on the same circumference, and the like. The engraved portions are arranged in a horizontal line so that the engraved portions are arranged in a horizontal line, and the common portion region and the main portion region are separated by a straight line, and one side thereof is defined as a divided region, or each gate is arranged substantially on a semicircle. Each engraved part is arranged in a semi-circular radial shape, the common part area and the main part area are separated by a semicircular line, and the inside is defined as a partitioned area. Arbitrarily designed in consideration of the runners and gates provided on the side That.

The present invention is applicable to any type of resin product as long as it can design a relatively small common part having a substantially identical shape from a plurality of types of molded products formed using a runnerless mold. It is also applicable as a runnerless mold for injection molding, and its packaging, knives, forks, and the like used in the above-mentioned instant foods and ice creams, etc.
In addition to molds such as spoons, toothbrushes and chopsticks of various sizes, box-shaped items such as cassette tape and videotape storage cases that can be designed with corners as common parts, and trays Examples of the molds used for molding the types and the like can be given.

[0018]

According to the runnerless mold for injection molding of the present invention, a common part region for molding a molded part common part and a main part for molding a molded part principal part are formed on a plurality of fixed side engraved parts formed on the fixed side. An area is provided, and a gate of a runner is opened in a common part area of the fixed side carved part, and a part forming a main part area of these fixed side carved parts on the fixed side is an island-shaped independent divided fixed side. The main fixed side is detachably divided from the main fixed side, and at the moving side, a portion forming the main part area of the moving side engraving corresponding to at least the common part area of the fixed side engraved part is detachably divided from the main moving side,
The divided fixed side and the movable side are interchangeably formed with respect to the main fixed side, and the divided movable side is interchangeably formed with respect to the main fixed side. On the other hand, by preparing a divided fixed side and a divided moving side corresponding to a plurality of types of molded products, the main fixed side is made common, and only the divided fixed side and the moving side (divided moving side) are exchanged to produce multiple types. Can be manufactured.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments. 1 to 5 show a multi-cavity runnerless mold for injection molding according to an embodiment of the present invention. This mold is for manufacturing a spoon for an instant food by injection molding of a general-purpose thermoplastic resin such as a polystyrene resin, and is fixed to a fixed die plate 4 of an injection molding machine and introduced from an injection device (not shown). Having a plurality of runners 5 through which molten resin flows and a plurality of gates 6 provided at the ends of the runners 5 and constantly heating the runners 5 immediately before each of the gates 6 during a molding operation. Fixed side 1 having external heating means and movable die plate 7 of the injection molding machine
And a plurality of engraved portions 3 formed between the fixed side 1 and the movable side 2 and filled with the molten resin from the respective gates 6 at the time of molding.
In this embodiment, as shown in FIG. 4, the plurality of runners 5, the plurality of gates 6, and the heating means for each runner 5 are integrally formed as a multi-cavity nozzle 8.

The plurality of engraved portions 3 formed between the fixed side 1 and the movable side 2 are shown in FIGS.
As shown in the figure, a common portion region 9a for forming a small tip portion of the handle of the spoon and a main portion region 9b for forming most of the remaining portion of the spoon are formed in the fixed side engraving portion 9. Further, in the fixed side engraved portion 9, the common portion regions 9a are arranged close to each other and are intensively arranged in two horizontal rows in the rectangular divided region 10,
Each gate 6 of the multi-cavity nozzle 8 is opened in each of the common area 9a.

In the fixed side 1, a portion forming the main portion area 9b of each of the fixed side engraved portions 9 is removably divided into two divided fixed sides 1b from the main fixed side 1a of the other main portions. ing. First, the divided fixed side 1b is constituted by a flat mold plate having the main portion region 9b formed on one surface, and the main fixed side 1a is a mold plate obtained by appropriately combining a plurality of dies. The common portion region 9a is formed on the uppermost mold surface, and an opening size larger than the size of the divided fixed side 1b is provided near the terminal side of the common portion region 9a. Mounting recess 12 is formed. And the split fixed side 1b
After being fitted into the mounting recess 12 of the main fixed side 1a,
Position adjusting fixtures 13 such as wedges so that the main area 1b on the split fixed side 1b is aligned with the common area 1a on the main fixed side.
The jig 13 is attached and fixed by the position adjustment, and is removed from the attachment recess 12 after removing the opposite position adjustment fixture 13. in this way,
The fixed side 1 is such that the divided fixed side 1b is replaceable with respect to the main fixed side 1a.

On the other hand, as shown in FIGS. 1, 2 and 5, the movable side 2 is formed with a plurality of movable side engraved portions 14 as the engraved portions 3, and the movable side engraved portion 14 is a fixed side engraved portion. 9 common part region 9a and main part region 9b
And a common area 14a and a main area 14b. Note that the two-dot chain line A in FIG. 2 is a boundary line added for convenience to indicate a boundary between the common portion region 14a and the main portion region 14b. As for the moving side 2, the portion where the common part area 14 a and the main part area 14 b of the moving side engraving part 14 are formed is divided into two divided moving sides 2.
The part b is detachably detachable from the main moving side 2a of the other main part. First, the divided moving side 2b is constituted by a flat mold plate having the common part region 14a and the main part region 9b both formed on one surface, and one main moving side 2a is provided with a plurality of molds. Are appropriately combined with each other, and the uppermost mold surface has the divided moving side 2
Mounting recess 1 having an opening size larger than the size of b
5 are formed. The divided moving side 2b is mounted and fixed by being fitted into the mounting concave portion 15 of the main moving side 2a and then adjusted in position by a position adjusting and fixing jig 13 such as a wedge so as to match a predetermined fixed position. Conversely, after the position adjustment fixture 13 is removed, it is detached from the mounting recess 15. in this way,
The moving side 2 also has a divided moving side 2 with respect to the main moving side 2a.
b is exchangeable.

Here, the mounting recess 1 on the main fixed side 1a
5 and 6, a mold 20 having a mounting recess hole formed according to the opening shape of the mounting recess.
A concave portion formed by combining the mold 20 and a flat mold 21 that is in close contact with the back surface of the mold 20. Also,
As shown in FIGS. 5 and 8, the mounting recess 15 on the main moving side 2a has a mounting recess hole formed in accordance with the opening shape of the mounting recess, as shown in FIGS. 30 is a concave portion formed by combining a flat plate mold 31 that is in close contact with the back surface side of 30. As shown in FIG. 5, each of the divided fixed side 1b and the mounting concave portion 12 and the divided moving side 2b and the mounting concave portion 15 have a vertical surface (perpendicular to the front and back surfaces) as shown in FIG. Since it is formed, when it is attached, its joints are securely tightly joined to each other without any gap.
Note that both the mounting recess 12 and the mounting recess 15 are not limited to the above-described forming method, and may be formed by, for example, forming a recess in a flat plate if high-precision processing or the like is possible. Good.

In this embodiment, a sprue bushing (not shown) connected to the injection device, a manifold connecting the sprue bushing and the multi-cavity nozzle 8, and a sprue bushing, a manifold, and a multi-cavity nozzle are provided. Although not particularly shown, the heaters for heating 8 and the like are all incorporated in the main fixed side 1a.

The runnerless mold of this embodiment is used as follows. First, as shown in FIG.
Is fixed to the fixed die plate 4 of the injection molding machine, and then the divided fixed side 1b is aligned with the mounting concave portion 12 of the main fixed side 1a by the position adjustment fixing jig 13 (the concave portion 1).
2 so as to be offset to one adjacent corner thereof to form the fixed side 1. On the other hand, as shown in FIG. 8, the main moving side 2a is fixed to the moving die plate 7 of the injection molding machine.
Is fixed while aligning with the jig 13 and moving side 2
Is configured. Then, as shown in FIGS. 1, 4 and 5, the movable side 2 is moved with respect to the fixed side 1 so that the two are brought into close contact with each other and the mold is closed. The molten resin is injected from each gate 6 into the engraved portion 3 formed by the fixed-side engraved portion 9, the movable side and the engraved portion 14, and the cooling resin holes (not shown) provided on the fixed side 1 and the movable side 2 are respectively provided. The molten resin in the engraving portion 3 is cooled by introducing cooling water into the engraved portion 3 and solidified. Thereafter, the movable side 2 is retracted to open the mold, and at the time of opening the mold, the product spoon, which is a molded product, is released from the engraved portion 3 by the ejector pins 11 provided on the movable side 2. FIG.
5 of P.5 L. Indicates a parting line surface.

When another molded product, for example, a fork for instant food is molded using the runnerless mold of this embodiment, as shown in FIGS. Is replaced with a separate fixed side 1c for fork molding prepared separately, and in accordance with this, the divided moving side 2b of the moving side 2 (not shown) is also replaced with a fork forming one, which is completely different from the case of spoon molding. Similarly, a product fork may be formed by injecting molten resin into the engraved portion 3 formed between the fixed side 1 and the movable side.

In this embodiment, as shown in FIG. 2, the common portion area 1 of the movable side engraving portion 14 is provided on the divided movable side 2b.
4a and the main portion region 14b are formed together, but the present invention is not limited to this.
Only the main part region 14b may be formed on the divided moving side 2b. In this case, the common area 14a may be formed on the main moving side 2a.

[0028]

According to the runnerless mold for injection molding of the present invention, the fixed side is the main fixed side including the main part, and the main part for molding the main part of the molded part which occupies most of the molded part in the engraved part on the fixed side. The moving side is also divided into the main moving side and the divided moving side including the main part area of the moving side engraving corresponding to at least the main part area of the fixed side engraving part. Since the divided fixed side and the movable side are interchangeably formed with respect to the main fixed side, and the divided movable side is interchangeably formed with respect to the main movable side. By preparing a divided fixed side and a divided movable side (divided movable side) corresponding to a plurality of types of molded products, only the divided fixed side and the movable side (divided movable side) are exchanged to prepare a plurality of types. Can manufacture molded products

For this reason, when molding a plurality of types of products such as knives, forks and spoons, one main fixed side and a divided fixed side and a movable side (divided movable side) corresponding to each product are prepared. As long as the main fixed side of the fixed side, which is the heaviest and has the highest manufacturing cost, is shared, the advantages of the runnerless mold are not impaired,
In addition to significantly reducing the production cost of the runnerless mold required to manufacture multiple types of molded products, another type of product can be obtained by replacing only the relatively lightweight split fixed side and movable side (divided movable side). Since the molding can be performed, the mold changing operation becomes extremely easy. In addition, since the divided fixed side and the divided moving side in which the engraved portion relating to the main part of the molded article largely depends on the type change of the molded article are small in size,
It is possible to further reduce the manufacturing cost of the runnerless die required for manufacturing the above-described plural types of molded products and further facilitate the die changing operation.

[Brief description of the drawings]

FIG. 1 is a partially exploded perspective view showing a multi-cavity runnerless mold according to an embodiment of the present invention.

FIG. 2 is an explanatory front view showing the configuration on the moving side in FIG. 1;

FIG. 3 is an explanatory front view of a partially cut-away portion of FIG. 1;

FIG. 4 is an explanatory sectional view taken along the line IV-IV in FIG. 3;

FIG. 5 is an explanatory sectional view taken along line VV of FIG. 3;

FIG. 6 is an exploded explanatory view of the fixed side of FIG. 1 showing the divided fixed side and the main fixed side.

FIG. 7 is an explanatory plan view showing a fixed-side engraving portion of FIG. 1;

FIG. 8 is an exploded view of the moving side of FIG. 1 showing the divided moving side and the main moving side.

9 is an exploded explanatory view of a fixed side similar to FIG. 6, showing another divided fixed side and a main fixed side.

FIG. 10 is an explanatory plan view similar to FIG. 7, showing the fixed-side engraving portion of FIG. 9;

[Explanation of symbols]

1 fixed side, 1a main fixed side, 1b, 1c divided fixed side, 2 movable side, 2a main movable side, 2b divided movable side,
3 ... carved part, 4 ... fixed die plate, 5 ... runner, 6
.. Gate, 7 moving die plate, 9 fixed side engraved part, 9a common area, 9b main area, 10 partitioned area, 11 ejector pin, 12, 15 mounting recess, 14 engraved moving side Section, 14a... Common area, 1
4b: Main area.

Claims (2)

(57) [Claims] 1. A runner fixed to a fixed die plate of an injection molding machine, through which a molten resin introduced from an injection device flows, and a gate provided at an end of the runner. A fixed side having a heating means for constantly heating the runner during the molding operation, a movable side attached to the movable die plate of the injection molding machine, and a gate formed between the fixed side and the movable side, and from the gate during molding. In a runnerless mold for injection molding having an engraved portion filled with a molten resin, the fixed-side engraved portion formed on the fixed side has a small substantially identical shape designed from a plurality of types of molded products. Providing a common part area for molding the article common part and a main part area for molding the main part of the molded article occupying most of the molded article, and opening the gate of the runner in the common area of the fixed side engraved part; Solid The part forming the main part area of this fixed side engraved part on the side is detachable from the main fixed side of the other main part to the mounting recess formed on the main fixed side from the main fixed side of the other main part On the other hand, on the moving side engraving part formed on the moving side, a common part area and a main part area corresponding to the common part area and the main part area of the fixed side engraving part are provided. The part forming the main part area of the moving side engraving part corresponding to at least the main part area of the fixed side engraving part is regarded as an island-shaped independent divided moving side and the main moving side is the main moving side from the main moving side of the other main parts The main fixed side is divided so as to be detachably attached to the mounting recess formed in the main fixed side, and the divided fixed side and the movable side are exchangeable with respect to the main fixed side. Runnerless mold for injection molding, characterized in that the replaceable the divided movable against. 2. A multi-cavity mold having a plurality of runners and gates formed on a fixed side thereof and a plurality of engraved portions between a solid side and a movable side. 2. The runnerless mold for injection molding according to claim 1, wherein the common portion regions of the formed fixed side engraved portions are arranged close to each other in a predetermined partitioned region, and the partitioned region is positioned on the main fixed side.