JPH06182860A - Hollow injection molded piece with partition and molding method therefor - Google Patents

Abstract

PURPOSE:To extend an application of a hollow injection molded piece by a method wherein in the hollow injection molded piece, partitions for partitioning a hollow part to its intermediate height are integrally molded at predetermined intervals. CONSTITUTION:Firstly, a melt resin is injected into a mold cavity 4 in the state that a movable core 5 is projected into the mold cavity 4 to its intermediate height. Next, a pressurized fluid is injected into the melt resin in the mold cavity 4 to form a hollow part 1. With the injection of the pressurized fluid, the capacity of the mold cavity 4 is increased by moving a movable mold 3a. Moreover, the movable core 5 is retracted from inside the mold cavity 4. With the increase of the capacity of the mold cavity 4, a large hollow part 1 is formed. The resin existing around a space replacing the retracted movable core 5 moves to the space, and the space is filled with the resin as a partition 2. After that, the resin in the mold cavity 4 is cooled, the pressurized fluid in the hollow part 1 is discharged, and the mold 3 is opened. In this manner, a hollow injection molded piece with partition is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow injection molded article with a partition having a new internal shape, which can be used as, for example, a balancer (or balance ring) of a washing machine, and a molding method thereof.

[0002]

2. Description of the Related Art Conventionally, as a method of molding a hollow injection-molded article, injection of molten resin into a mold cavity and pressurization of a pressurized fluid are carried out, and a region where the molten resin is pushed away by the pressurization of the pressurized fluid is carried out. A method of forming a hollow portion is known (Japanese Patent Publication No. 57-14968). In the hollow injection-molded product obtained by this molding method, since the shape of the hollow part is determined by the natural flow of the molten resin that is pushed away by the pressurized fluid, the peripheral surface of the hollow part is formed as a substantially smooth surface. Become.

[0003]

By the way, the hollow injection-molded product as described above has a hollow part formed therein in order to reduce the weight of the molded product and to prevent sink marks, and the hollow part itself is formed. It doesn't try to get any new functionality using.

On the other hand, in order to obtain some new function by utilizing the formed hollow portion, various functions can be achieved if the hollow portion can have various uneven shapes like the outer surface shape of the molded product. There is a possibility that they will be connected, but there is a problem that it is difficult to connect to a new function with a simple hollow portion whose peripheral surface is almost smooth.

It is an object of the present invention to expand the application of hollow injection-molded articles by providing unevenness in the hollow portion.

[0006]

To this end, in the invention of claim 1, as shown in FIG. 1, in the hollow injection-molded article, the partition 2 for partitioning the hollow portion 1 up to the intermediate height is
It is a hollow injection-molded product with a partition integrally formed at required intervals.

Further, in the invention of claim 4, as shown in FIG. 2, in order to obtain the hollow-injection molded article with the partition,
The movable core 5 capable of expanding the volume of the mold cavity 4 and projecting and retracting into the mold cavity 4 is being moved into the mold cavity 4 of the mold 3 having the partition 2 formation position. With the child 5 protruding to the middle of the mold cavity 4, the molten resin is injected and the pressurized fluid is injected, and the volume of the mold cavity 4 is expanded and the movable core 5 is retracted. is there.

Further, according to the fifth aspect of the invention, as shown in FIG. 4, the volume of the mold cavity 4 can be expanded so as to obtain the hollow injection molded product with the partition. The movable core 5 capable of projecting and retracting into the mold cavity 4 of the mold 3 having the partition 2 forming position,
With the movable core 5 retracted from the inside of the mold cavity 4, injection of molten resin and pressurization of a pressurized fluid are performed, the volume of the mold cavity 4 is further expanded, and the middle part of the mold cavity 4 of the movable core 5 is expanded. Is to be projected.

[0009]

The present invention will be further described with reference to the drawings.

FIG. 1 is a view showing a first embodiment of a hollow injection-molded product with a partition according to the present invention, in which a predetermined space is provided in the hollow portion 1 to partition the hollow portion 1 up to an intermediate height. The partition 2 is formed.

FIG. 2 is an explanatory view of a molding method of the hollow injection molded product with the partition.

The mold 3 used in this molding method has a movable core 5 capable of expanding the volume of the mold cavity 4 and projecting and retracting into the mold cavity 4. There is.

One of the molds 3 shown is a movable mold 3.
In a, the other is a fixed mold 3b, and the volume of the mold cavity 4 can be expanded by moving the movable mold 3a in the mold opening direction. In addition, the movable core 5
Is on the side of the movable mold 3a, and each partition 2 shown in FIG.
Is provided at the forming position.

First, as shown in FIG. 2A, molten resin is injected into the mold cavity 4 with the movable core 5 protruding to the middle of the mold cavity 4.

Then, as shown in FIG. 2B, a pressurized fluid is pressed into the molten resin in the mold cavity 4 to form the hollow portion 1. The pressurization of the pressurized fluid may be performed at the same time as the injection of the remaining molten resin after injecting a part of the molten resin to be injected, or after the completion of the injection of the molten resin to be injected.

The pressurized fluid may be a liquid such as an oligomer or liquid paraffin, but gas is generally used. The gas may be air or the like, but an inert gas such as nitrogen is preferable. Pressure of pressurized fluid is usually 10-300k
It is preferable that the pressure is about g / cm ² and the pressure is low in the range where molding is possible from the viewpoint of safety management.

With the pressurization of the pressurized fluid, the movable die 3a
Is moved to increase the volume of the mold cavity 4, and the movable core 5 is retracted from the mold cavity 4. It is preferable that the movable core 5 is retracted from the mold cavity 4 after the volume of the mold cavity 4 has been expanded to some extent or after the volume of the mold cavity 4 has been expanded.

When the volume of the mold cavity 4 is expanded and the movable core 5 is retracted as described above, the volume of the mold cavity 4 is expanded as shown in FIGS. The large hollow portion 1 is formed, and the resin existing around the movable core 5 is moved and filled in the retreat trace of the movable core 5, so that the partition 2
Will be formed.

After that, the resin in the mold cavity 4 is cooled, the pressurized fluid in the hollow portion 1 is discharged, the mold 3 is opened, and the molded product is taken out. It is possible to obtain a hollow injection-molded product with a cover.

The hollow injection molded article with a partition according to the present invention can be used, for example, as a balancer (or balance ring) of a washing machine. In this case, a hollow injection-molded product with a partition is molded into an annular shape, and when used, the
As shown in, the liquid (for example, water) may be enclosed in the hollow portion 1 to a depth that does not exceed the partition 2.

The height and interval of the partition 2 may be appropriately determined according to the intended use. The volume of the hollow portion 1 is preferably 40% or more, more preferably 60% or more. This hollow ratio is mainly determined by the expansion ratio of the volume of the mold cavity 4 due to the movement of the movable mold 3a.

FIG. 4 is a view showing a second embodiment of a hollow injection-molded article with a partition according to the present invention, in which a predetermined space is provided in the hollow portion 1 to partition the hollow portion 1 up to an intermediate height. The partitions 2 are alternately formed on the upper and lower sides.

The partition hollow injection molded product can be molded by providing the movable core 5 not only on the movable die 3a side but also on the fixed die 3b side in the method described with reference to FIG.

FIG. 5 shows a third embodiment of a hollow injection-molded article with a partition according to the present invention, in which the partition 2 is formed not in a plate shape but in a convex shape which becomes a depression when viewed from the surface side of the molded article. It has become a thing.

FIG. 6 is an explanatory view of a molding method of the hollow injection-molded product with the partition.

The mold 3 used in this method is the same as the mold 3 used in the method shown in FIG. 2. First, as shown in FIG. 6A, the mold cavity is retracted with the movable core 5 retracted. Four
The molten resin is injected into the inside, and as shown in FIG. 6B, the pressurized fluid is injected during or after the injection of the molten resin to form the hollow portion 1.

Next, as shown in FIG. 6 (b), the movable die 3a is moved to expand the volume of the die cavity 4. At this time, the movable core 5 is not moved but is projected into the mold cavity 4 which is gradually expanded as the movable mold 3a retracts. Then, as the hollow portion 1 is enlarged, a part of the resin is pushed up by the movable core 5, whereby the partition 2 is formed.

FIG. 7 is an explanatory view of another molding method of the hollow injection-molded article with the partition shown in FIG. 5, and as shown in FIG. 7 (a), the molten resin is retracted with the movable core 5 retracted. Is performed, and then a pressurized fluid is pressed in as shown in FIG. 7B to form the hollow portion 1, as in the method of FIG.

In this method, when the volume of the mold cavity 4 is expanded by the movement of the movable die 3a, the movable core 5 is moved together with the movable die 3a, and the movable core 5 is moved as shown in FIG. 7 (b). This method is different from the method shown in FIG. 6 in that, after being once retracted, it is advanced again as shown in FIG. 7C to project into the mold cavity 4. In this method, when the movable core 5 is advanced, the resin in the mold cavity 4 is pushed up to form the partition 2.

FIG. 8 is also an explanatory view of another molding method of the hollow injection-molded article with the partition shown in FIG.

The mold 3 used in this method is provided with an uneven shape for forming the partition 2 on the surface of the mold cavity 4 on the fixed mold 3b side, and is directed to the position corresponding to the concave part of this uneven shape. The movable core 5 is provided on the movable die 3a side.

First, as shown in FIG. 8 (a), molten resin is injected into the mold cavity 4 with the movable core 5 protruding, and further, as shown in FIG. 8 (b), the molten resin is added. A hollow gas 1 is formed by pressurizing a pressurized gas.

Particularly in this method, as shown in FIG. 8B, the movable core 5 is moved at the same time when the volume of the mold cavity 4 is expanded by the movement of the movable mold 3a or after the volume of the mold cavity 4 is expanded. Retreat. Then, the hollow portion 1 is enlarged, and the partition 2 is formed by the convex-concave convex portion provided on the fixed mold 3b side.

FIG. 9 shows a fourth embodiment of a hollow injection-molded article with partitions according to the present invention, in which the partitions 2 having a convex shape are formed alternately in the upper and lower directions.

FIG. 10 is an explanatory view of a molding method of the hollow injection molded product with the partition.

The mold 3 used is the same as that used in the method of FIG. 8 except that molding is performed without retracting the movable core 5 to the end. According to this molding method, partitions 2 are alternately formed on the upper and lower surfaces by the uneven shape on the fixed mold 3b side and the movable core 5 protruding into the mold cavity 4.

[0037]

Industrial Applicability The present invention is as described above, and by having the partition 2 in the hollow portion 1, the hollow injection molded article can be used for a new application such as a balancer of a washing machine. You can Further, such a hollow injection molded product having irregularities in the hollow portion 1 can be easily molded, and the application of the hollow injection molded product can be expanded.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of a hollow injection-molded product with a partition according to the present invention.

FIG. 2 is a diagram showing an example of a method of molding the hollow injection-molded product with partitions of FIG.

FIG. 3 is a view showing a state in which a liquid is enclosed in a hollow portion of the partition hollow injection molded product of FIG.

FIG. 4 is a view showing a second embodiment of the hollow injection-molded product with partition according to the present invention.

5 is a diagram showing an example of a molding method of the hollow injection molded product with a partition in FIG.

FIG. 5 is a view showing a third embodiment of the hollow injection-molded product with partition according to the present invention.

FIG. 6 is a diagram showing an example of a method of molding the hollow injection-molded product with partitions of FIG.

FIG. 7 is a diagram showing another example of the method of molding the hollow injection-molded product with partitions of FIG.

FIG. 8 is a diagram showing another example of a method of molding the hollow injection-molded product with partitions of FIG.

FIG. 9 is a view showing a fourth embodiment of the partition hollow injection-molded product according to the present invention.

FIG. 10 is a diagram showing an example of a method of molding the hollow injection-molded article with partition of FIG. 9.

[Explanation of symbols]

 1 Hollow part 2 Partition 3 Mold 3a Moving type 3b Fixed type 4 Mold cavity 5 Movable core

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[Procedure amendment]

[Submission date] December 2, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a first part of a hollow injection molded product with a partition according to the present invention.
It is a figure which shows the Example of.

FIG. 2 is a diagram showing an example of a molding method for the hollow injection-molded product with a partition shown in FIG.

FIG. 3 is a diagram showing a state in which a liquid is enclosed in the hollow portion of the hollow injection molded product with a partition in FIG. 1.

FIG. 4 is a second hollow injection-molded article with a partition according to the present invention.
It is a figure which shows the Example of

FIG. 5 is a third part of the hollow injection-molded article with partition according to the present invention.
It is a figure which shows the Example of.

FIG. 6 is a diagram showing an example of a method of molding the hollow injection-molded product with partitions in FIG.

FIG. 7 is a diagram showing another example of a method of molding the hollow injection-molded product with partitions of FIG.

FIG. 8 is a diagram showing another example of a method of molding the hollow injection-molded article with partition of FIG.

FIG. 9 is a fourth example of the hollow injection-molded article with partition according to the present invention.
It is a figure which shows the Example of.

FIG. 10 is a diagram showing an example of a molding method for the hollow injection-molded product with partitions in FIG.

[Explanation of reference numerals] 1 hollow part 2 partition 3 mold 3a moving mold 3b fixed mold 4 mold cavity 5 movable core

Claims (5)

[Claims] 1. A hollow injection-molded article with a partition, characterized in that in the hollow injection-molded article, partitions for partitioning the hollow portion up to an intermediate height are integrally formed at required intervals. 2. A hollow injection molded article with a partition, wherein the hollow injection molded article has an annular shape. 3. The hollow injection-molded product with a partition according to claim 2, wherein the hollow part of the hollow injection-molded product is filled with a liquid. 4. A movable core having a movable core which can expand the volume of the mold cavity and can be projected and retracted into the mold cavity into the mold cavity of a mold having a partition forming position. 2. The partition according to claim 1, wherein the molten resin is injected and the pressurized fluid is injected in a state in which the mold protrudes to the middle of the mold cavity, and further the volume of the mold cavity is expanded and the movable core is retracted. Method for molding hollow injection molded products. 5. A movable core having a movable mold core capable of expanding the volume of the mold cavity and projecting and retracting into the mold cavity is provided in the mold cavity of a mold having a partition forming position. Injecting the molten resin and pressurizing the pressurized fluid in a state where the mold retreats from the inside of the mold cavity, further expanding the volume of the mold cavity and projecting the movable core to the middle part of the mold cavity. The method for molding a hollow injection-molded article with a partition according to claim 1.