JPH06312439A - Runnerless mold for injection molding - Google Patents

Abstract

PURPOSE:To easily produce two or more kinds of molded products by respectively setting the common region and principal region to two or more kinds of molded products to the carved parts of a fixed mold and setting the principal regions as divided and fixed sides to divide the same in a manner detachable from other main fixed side. CONSTITUTION:A mold is constituted of a fixed mold 1 and a movable mold. The fixed mold 1 is attached to the fixing die plate 4 of an injection molding machine and has not only the runner and gate of a molten resin but also a heating means. The movable die 2 is attached to the moving die plate 7 of the injection molding machine. A carved part 3 filled with a molten resin is provided between both molds. In this case, the common regions 9a and principal regions 9b in two more kinds of molded products are respectively set to the carved part 9 of the fixed mold 1 and the gates of runners are opened to the common regions 9a. The principal regions 9b are set as divided and fixed sides 1b to be made detachable from other main fixing sides 2a.

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 in particular, it is provided with a heating means for constantly heating a runner up to just before a gate opening in an engraving portion during the molding operation. The present invention relates to an injection-molding runnerless mold for use in an injection molding machine that injection-molds a target resin product without taking out a runner such as a runner as a molded product.

[0002]

2. Description of the Related Art In runnerless molds, runners such as sprues and runners are not taken out as molded products. For this reason, it is necessary to carry out post-finishing work such as runner removal work to remove these sprues and runners from molded products after molding. Because there is no
It has the advantages of high productivity, automation of product molding to packaging, no loss of raw material resin, and shortening of molding cycle.

However, in such a runnerless mold, it is necessary to constantly heat the runner up to the gate opening in the engraving portion during the molding operation to keep the resin supplied from the gate to the engraving portion in a molten state. Therefore, there is a problem in that it is necessary to incorporate a heating means in the mold, and the mold structure, especially the structure on the fixed side thereof is inevitably complicated and the manufacturing cost of the mold becomes extremely high. Moreover, in this runnerless die, the die itself becomes large and its weight is heavy, and for example, in the case of taking 20 spoons for ice cream, the weight reaches about 1.2 tons. In order to control the temperature and operation, it is necessary to connect to peripheral equipment such as temperature control equipment and hydraulic equipment with an extremely large number of wirings and pipes. There is also a problem that it takes a great deal of labor and time of several tens of hours in some cases.

However, in recent years, for example, as demand for instant foods, ice creams, and the like has increased, the uses, consumers, and traders of the packagings, knives, forks, spoons, etc. used in these instant foods, ice creams, etc. Diversified tastes, and for that,
Not only products with the same size and shape, but also products with different shapes and sizes must be manufactured according to the application and preference, and relatively few and many resin molded products are manufactured. 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 molding cycle. It is said that the manufacturing cost is high, and that a great deal of labor and time are required for the die replacement work, and thus it is unsuitable for manufacturing a large number of resin molded products with a relatively small number.

[0006]

Therefore, the inventor of the present invention
As a result of repeated studies on improvement of the runnerless mold in order to solve such a problem, as for the fixed side of the runnerless mold, most of the fixed side including the gate opening on the fixed side engraved part is the main fixed side. As a common part, the fixed side engraved portion formed on the fixed side is detachably formed on the main fixed side as a split fixed side.
As a result, a runnerless mold has been completed, and the present invention has been achieved by changing only the split fixed side and the moving side when the item of the resin molded product to be manufactured and its size and shape are changed.

Therefore, an object of the present invention is to provide a runnerless mold which is excellent in productivity, can easily correspond to automation of a production line, has no loss of raw material resin, and can shorten a molding cycle. A runnerless for injection molding that does not impair the advantages and is suitable for manufacturing a large number of resin molded products while suppressing the mold manufacturing cost as much as possible, and also facilitates mold replacement work. It is to provide the mold.

[0008]

That is, according to the present invention, there is provided 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 just before the gate during the molding operation, a moving side attached to the moving die plate of the injection molding machine, and the fixed side and the moving side. In a runnerless mold for injection molding, which has a carved part formed between them and filled with molten resin from the gate at the time of molding, in the fixed side carved part formed on the fixed side, the shape of a plurality of types of molded products A common part area for molding a common part of a molded product of the same shape and a main part region for molding a main part of the molded product that occupies most of the molded product are provided. The gate of the runner is opened in, and the part forming the main part region of this fixed side engraving part on the fixed side is divided as the fixed side and detachably divided from the main fixed side of the other main part. On the other hand, it is a runnerless mold for injection molding in which the split fixed side and the moving side can be exchanged.

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 the molded product molded using this runnerless mold, and the main fixed side. On the other hand, when the split fixed side and the moving side are exchanged with each other and a molded product of a different type in item, size or shape is molded, at least this fixed molded product is fixed. The molded part is molded as a molded part common part having substantially the same shape and size so that the part molded by the common part region on the side completely matches. The shape of the common side area on the moving side may be slightly changed in shape and size depending on the type of molded product to be molded.

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

Further, in the present invention, a gate of the molten resin runner is opened in the common part region of the fixed side engraved portion, and a portion forming a main part region of the fixed side engraved portion on the fixed side is formed. As the split fixed side, it is detachably split from the main fixed side of the other main part. When dividing the fixed side into the main fixed side and the split fixed side, the common part area of the fixed side engraving part is located on the main fixed side, and the main part area of the fixed side engraved part is located on the divided fixed side. It suffices to do so, and it is not particularly limited by the arrangement of the runners, 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. Is preferably designed so that its volume is as small as possible in consideration of its strength and rigidity. Here, if the main fixed side is made of a relatively hard and good quality material such as Swedish steel, and the split fixed side is made of an inexpensive steel material that is relatively soft and easy to machine, damage to the main fixed side will occur as much as possible. Besides, it is possible to manufacture the divided fixed side at a lower cost.

Further, in the present invention, although not particularly limited, heating means for constantly heating the runner up to immediately before the gate during the molding operation, and in the case of the valve gate system, a hydraulic device for its operation. Also, in the case of a hot chip gate, it is preferable that the relatively expensive parts such as the chip heating means are provided on the main fixed side as much as possible to be common, and more preferably connected to the injection device. The sprue bushing, the manifold connected to the sprue bushing, the nozzle connected to the manifold, the heater for heating the sprue bushing, the manifold, the nozzle, etc. are incorporated into the main fixed side to be common, and the split fixed side Is a flat plate having only the main part of the engraved part or in addition to this 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 have to be located only on the main fixed side, and may be formed from this main fixed side to the split fixed side. Separate cooling water holes may be provided on the divided fixed side.

The present invention can be applied to any type of mold as long as it is a runnerless mold.
Applicable to single-cavity molds, multi-cavity molds such as two-cavity and three-cavity molds, and multi-cavity molds such as ten-cavity and twenty-cavity molds. Besides, it can be applied regardless of the gate method such as the valve gate method or the hot tip gate method.

Further, the runnerless mold of the present invention is a multi-cavity mold in which a plurality of runners and gates are formed on the fixed side and a plurality of engraved portions are provided between the solid side and the moving side. In some cases, it is preferable that the common part areas of the fixed-side engraved portions formed on the fixed side are arranged close to each other in a predetermined divided area, and the divided area is located on the main fixed side. As for the partitioned area where this common area is provided, gates for each runner are opened in each common area on the fixed side, so consideration should be given to the placement of the molten resin runners that reach these gates. The gates can be designed to have a relatively wide rectangular shape in which the gates are arranged in two horizontal rows, or a circular shape so that the gates are arranged on the same circumference. Are arranged in a horizontal row so that the common area and the main area are separated by a straight line to form a partition area on one side, or the gates are arranged in a substantially semicircle. The number of engraved parts formed on one die and the main fixing are such that the engraved parts are arranged in a semi-circular shape and the common part area and the main part area are separated by a semicircle line to define the inside as a partition area. Designed arbitrarily considering the runners and gates installed on the side That.

Here, with respect to the partition area in which the common area of each fixed side engraved portion is concentratedly arranged on the main fixed side, the positioning is easy when the divided fixed side is attached to this main fixed side. Therefore, it is preferable that the peripheral edge of the divided fixed side is in contact with the divided fixed side by a tapered surface, which facilitates the positioning of the divided fixed side with respect to the partitioned area on the main fixed side in the replacement work of the divided fixed side. , Its work efficiency is improved.

The present invention can be applied to any resin product, as long as it is a molded product capable of designing a relatively small common part of the molded product having a relatively small shape from a plurality of types of molded products molded by using a runnerless mold. It can also be applied as a runnerless mold for injection molding, and its packaging, knife, fork, etc. used in the above-mentioned instant foods, ice creams, etc.
Not only molds such as spoons, but also toothbrushes and chopsticks of various sizes, box-shaped items such as cassette tape and video tape storage cases whose corners can be designed as common parts for molded products, and trays Examples of the mold and the like used to mold the types and the like can be given.

[0017]

In the runnerless mold for injection molding of the present invention, a plurality of fixed-side engraved portions formed on the fixed side are molded with a small molded article common portion designed from a plurality of types of molded article shapes. There is a common part area for molding the main part of the molded product that occupies most of the shape of the molded product, and the gate of the runner is opened in the common part area of the fixed side engraving part, and the fixed side In the above, the part forming the main part region of the fixed side engraved part is detachably divided from the main fixed side of the other main part as the split fixed side, and the split fixed side and the moving side are separated from the main fixed side. Since it is formed so that it can be exchanged, by preparing a split fixed side and a moving side corresponding to a plurality of types of molded products for one main fixed side, the main fixed side is made common and the split fixed side and Replace only the moving side It is possible to manufacture a plurality of types of molded articles.

[0018]

EXAMPLES The present invention will be specifically described below based on examples. 1 to 4, a multi-cavity injection molding runnerless mold according to an embodiment of the present invention is shown. This mold is for producing a spoon for instant food by injection molding of general-purpose thermoplastic resin such as polystyrene resin, is fixed to a fixed die plate 4 of an injection molding machine, and is 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 end of the runners 5 and constantly heating the runners 5 up to immediately before each of the gates 6 during the molding operation. Fixed side 1 having external heating means and moving die plate 7 of injection molding machine
And a plurality of engraved portions 3 that are formed between the fixed side 1 and the movable side 2 and that are filled with molten resin from the gates 6 at the time of molding.
In addition, in this embodiment, the plurality of runners 5, the plurality of gates 6, and the heating means of each runner 5 are integrally formed as a multi-piece taking 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 FIG. 3, the fixed side engraved portion 9 is formed with a common portion region 9a for molding a small tip portion of the handle of the spoon and a main portion region 9b for molding most of the rest of the spoon. The common portion regions 9a are arranged in two rows in a row in a rectangular partitioned region 10 in close proximity to each other, and the gates 6 of the multi-cavity forming nozzle 8 are opened in the respective common portion regions 9a. is doing.

Further, the fixed side 1 is detachably divided from the main fixed side 1a of the other main portion as a divided fixed side 1b in which the portion forming the main portion region 9b of each fixed side engraved portion 9 is divided. As a result, the split fixed side 1b and the moving side 2 can be exchanged with respect to the main fixed side 1a.

In this embodiment, the split fixed side 1b is
A portion of the main fixed side 1a corresponding to the partitioned area 10 is hollowed out in a rectangular shape, and a rectangular opening 10 is formed in the substantially central portion.
It is formed in a flat plate shape having a, and the main fixed side 1
The outer peripheral surface of the partitioned area 10 of a and the opening 1 of the divided fixed side 1b
The inner peripheral surface 0a is joined with a taper surface, and the main fixed side 1a and the split fixed side 1b can be positioned only by fitting the partition area 10 of the main fixed side 1a into the opening 10a of the split fixed side 1b. It has become.

In this embodiment, a sprue bushing (not shown) connected to the injection device, a manifold connecting between the sprue bushing and the multi-piece taking nozzle 8, and the sprue bushing, the manifold, and the multi-piece taking nozzle. Although not particularly shown, a heater for heating 8 and the like is incorporated in the main fixed side 1a.

Therefore, according to the runnerless mold of this embodiment, first, as shown in FIG. 5, the main fixed side 1a is fixed to the fixed die plate 4 of the injection molding machine, and then the main fixed side 1a is divided and fixed. The side 1b is fixed to form the fixed side 1, and the moving side 2 attached to the moving die plate 7 of the injection molding machine is set to the fixed side 1 as shown in FIGS. 1 and 3. The molten resin is injected from each gate 6 of the multi-cavity nozzle 8 in the fixed side 1 to the engraved portion 3 formed between the fixed side 1 and the movable side 2, and the fixed side 1 and the movable side 2 are injected.
Cooling water is introduced into cooling water holes (not shown) provided in each of the above to cool and solidify the molten resin in the engraved portion 3,
After that, the moving side 2 is retracted, and at that time, the product spoon which is a molded product is released from the engraved portion 3 by the ejector pin 11 provided on the moving side 2.

Further, when another molded product, for example, a fork for instant food, is molded using the runnerless mold of this embodiment, as shown in FIGS. 7 and 8, the split fixed side 1b for spoon molding is used. Is replaced with a separately prepared split fixed side 1c for fork molding, and in accordance with this, the moving side (not shown) is also replaced with a fork molding side, and the fixed side 1c The product fork may be formed by injecting molten resin into the engraved portion formed between the moving side and the moving side.

[0025]

According to the runnerless mold for injection molding of the present invention, the main part of the molded product that occupies most of the molded product in the main fixed side including the main part of the fixed side and the fixed side engraved part is molded. It is divided into a split fixed side that includes a partial area, and the split fixed side and the moving side can be exchanged with respect to the main fixed side, so one main fixed side can accommodate multiple types of molded products. By preparing the divided fixed side and the movable side, only the divided fixed side and the movable side can be exchanged to manufacture a plurality of types of molded products.

Therefore, for example, when molding a plurality of types of products such as knives, forks and spoons, it suffices to prepare one main fixed side and a divided fixed side and a moving side corresponding to the respective products. Since the main fixed side of the fixed side, which is heavy and costly to manufacture, is shared, manufacturing of runnerless molds necessary for manufacturing multiple types of molded products without compromising all the advantages of runnerless molds The cost can be greatly reduced, and another type of product can be molded by exchanging only the relatively lightweight split fixed side and moving side, which makes the die exchange work extremely easy.

[Brief description of drawings]

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

2 is a partially cutaway front view of FIG. 1. FIG.

3 is a cross-sectional view taken along the line III-III of FIG.

4 is a cross-sectional explanatory view taken along the line IV-IV of FIG.

FIG. 5 is a view showing a split fixed side and a main fixed side.
FIG. 3 is an exploded view of the fixed side of FIG.

6 is an explanatory plan view showing the fixed side engraving portion of FIG. 1. FIG.

FIG. 7 is an exploded view of the fixed side, similar to FIG. 5, showing another split fixed side and a main fixed side.

FIG. 8 is a view showing a fixed side engraving portion of FIG.
It is a plane explanatory view similar to FIG.

[Explanation of symbols]

1 ... Fixed side, 1a ... Main fixed side, 1b, 1c ... Divided fixed side, 2 ... Moving side, 3 ... Engraving part, 4 ... Fixed die plate, 5 ... Runner, 6 ... Gate, 7 ... Moving die plate, 8
... Multi-piece taking nozzle, 9 ... Fixed side engraving part, 9a ... Common part region, 9b ... Main part region, 10 ... Section region, 10a
… Openings, 11… Ejector pins.

Claims (3)

[Claims] 1. A runner, which is fixed to a fixed die plate of an injection molding machine and through which molten resin introduced from an injection device flows, and a gate provided at the end of this runner, and up to immediately before this gate. The fixed side having a heating means for constantly heating the runner during the molding operation, the moving side attached to the moving die plate of the injection molding machine, and the fixed side formed between the fixed side and the moving side. In a runnerless mold for injection molding, which has a carved part filled with molten resin, the fixed side engraved part formed on the fixed side has a small substantially identical shape designed from the shape of multiple types of molded products. Provide a common part region for molding the product common part and a main part region for molding the molded product main part occupying most of the molded product, and open the gate of the runner in the common part region of the fixed side engraving part, Fixed On the side, the portion forming the main part region of this fixed side engraved portion is detachably divided from the main fixed side of the other main portion as the split fixed side, and the divided fixed side and the moving side are separated from this main fixed side. A runnerless mold for injection molding, characterized in that it can be replaced. 2. A mold is a multi-cavity mold in which a plurality of runners and gates are formed on the fixed side, and a plurality of engraved portions are provided between the solid side and the moving side, and the mold is provided on the fixed side. The runnerless mold for injection molding according to claim 1, wherein the common part regions of the formed engraved parts on the fixed side are arranged close to each other in a predetermined partition region and the partition region is positioned on the main fixed side. 3. The main fixed side partition area where the common area of each fixed side engraving section is integrated and the divided fixed side where the main part area of each fixed side engraved section is formed are tapered at the peripheral edge of the partition area. The runnerless mold for injection molding according to claim 2, wherein the surfaces are joined together.