JPH07308941A - Device for injecting/discharging of pressurized fluid - Google Patents

Abstract

PURPOSE:To provide a device for injecting/discharging a pressurized fluid, which is free from a fear of blockade by molten resin, the injected pressurized fluid is guided favorably into the molten resin and discharge of the pressurized fluid left behind within a hollow part of a molded body can be performed in a short time. CONSTITUTION:The title device is related to a device which is made to perform injection and discharge of the pressurized fluid through a pressurized fluid passage 3 to be formed of an inner wall of a sleeve 1 which is provided by making the tip open in a spatial part of an injection mold and a shaft core 2 which is inserted through the inside and advance and retreat are made possible in the axial direction. Therefore. the injecting or discharge device has a structure wherein a specific shaft core 2 comprised of a core body 21 and collar 22 is used, the pressurized fluid passage can be adjusted by allowing the tip part 21a of the core body 21 to perform the advance or the retreat within a specific range of a passage 3 and at the same time, the pressurized fluid passage can be closed released by making the front of the collar 22 to abut against separate from the rear of a flange part 12 of a sleeve 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressurized fluid pressurizing / discharging device used for manufacturing an injection molded product having a hollow portion. More specifically, a pressurized fluid is press-fitted into the molten resin injected into the mold space of the injection molding die, and the molten resin is pressed against the mold cavity surface to form a molded body having a hollow portion. The present invention relates to a pressurized fluid press-fitting / discharging device used in manufacturing a hollow injection molded product by a method of discharging a pressurized fluid in a hollow portion after cooling a body and then opening a mold to take out a molded product.

[0002]

2. Description of the Related Art Conventionally, as a method for producing an injection-molded article having a hollow portion, an amount of molten resin insufficient to fill a mold cavity of an injection-molding die is injected into the die cavity, or while it is being injected. There is known a method of pressurizing a pressurized fluid into a molten resin in a mold cavity to press the molten resin against the mold cavity surface to form a molded article having a hollow portion (for example, Japanese Patent Publication No. 57-14968). , Shokoku Sho 61-5
3208, JP-A-3-9820, JP-A-4
-357007, etc.). Then, when manufacturing an injection-molded article having a large hollow portion, a method of expanding the volume of the mold cavity following the step of injecting a molten resin into the mold cavity and subsequently pressurizing a pressurized fluid is described in the above-mentioned Japanese Patent Laid-Open No. It is proposed in JP-A-3-9820, JP-A-4-357099, and the like.

Further, a pressurized fluid pressurizing / discharging device used for discharging the pressurized fluid in the hollow portion after the pressurized fluid is press-fitted into the molten resin in the mold cavity to form the hollow portion and the molded body is cooled. As Japanese Patent Publication No. 48-41264, Japanese Patent Publication No. 59-19017, and Japanese Patent Laid-Open No. 5-17.
Known are those disclosed in Japanese Patent No. 7667, Japanese Patent Laid-Open No. 5-177668, Japanese Patent Laid-Open No. 5-200794, and the like.

In Japanese Patent Publication No. 48-41264, an elongated cylindrical projection having a pressurized fluid passage at its center is projected into the molten resin in a mold cavity to pressurize the pressurized fluid to cool the molten resin. After that, there is shown a device capable of withdrawing the pressurized fluid by retracting it outside the mold cavity, and Japanese Patent Publication No. 59-19017 discloses a cylinder device in the middle of a resin passage for guiding molten resin into the mold cavity. There is shown a device which is provided with a valve body for opening and closing the pressurized fluid passage, and through which the pressurized fluid is pressed into and discharged from the pressurized fluid passage.

However, these pressurized fluid pressurizing / discharging devices have the following drawbacks. That is, in the former case, the molten resin flows back into the pressurizing fluid passage of the cylindrical projection and closes it, and as a countermeasure against this, if the hole diameter of the pressurizing fluid passage is reduced, it takes time to pressurize and discharge the pressurizing fluid. Take
There is a problem that the molding cycle becomes long and the productivity is lowered.In the latter case, the molten resin flows back into the pressurized fluid passage through the valve body opened when the pressurized fluid is pressed. There is a problem that this is clogged and stable molding cannot be performed.

Japanese Unexamined Patent Publication No. 5-177667 and Japanese Unexamined Patent Publication No.
In Japanese Patent Application Laid-Open No. 177668 and Japanese Patent Application Laid-Open No. 5-200794, a device in which a gap between a cylindrical sleeve and a shaft core inserted in the sleeve is used as a pressurized fluid passage, and the pressurized fluid passage is disclosed. , A device in which a pressurized fluid is made to flow through but a molten resin is not allowed to invade by advancing and retracting the shaft core in the axial direction and is made variable between a narrowed state and an expanded state. Further, in these devices, when pressurizing fluid under pressure, the tip of the shaft core is partially projected into the mold, and the side surface of the projecting portion is used as a guide surface for the pressurized fluid. Further, it is disclosed that when the pressurized fluid is discharged, the shaft core is retracted to expand the pressurized fluid passage, and the pressurized fluid in the hollow portion can be discharged from the enlarged passage in a short time. There is.

However, even with these pressurizing fluid press-fitting / discharging devices, it is sometimes impossible to effectively prevent the clogging caused by the reverse flow of the molten resin, and the pressurizing fluid cannot be discharged from the hollow portion in a short time. It is not entirely satisfactory, and a part of the pressurized fluid that should be pressed into only the molten resin injected into the mold space leaks between the molten resin and the inner surface of the mold and is obtained. There have been problems such as a defective appearance of the molded product and insufficient pressurized fluid pressure in the hollow portion.

[0008]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned conventional technical problems, and pressurizes a pressurized fluid into a molten resin injected into a mold space of an injection molding die. Then, the molten resin is pressed against the mold cavity surface to form a molded body having a hollow portion, the pressurized fluid remaining in the hollow portion after cooling the molded body is discharged, and then the mold is opened to take out the molded product. Is a pressurizing fluid press-fitting / discharging device used when manufacturing a hollow injection-molded article, and there is no concern of blockage, the pressurized pressurizing fluid is well guided into the molten resin, and the pressurizing fluid in the hollow part is It is an object of the present invention to provide a pressurized fluid press-fitting / discharging device capable of discharging a pressurized fluid in a short time.

[0009]

As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have found that the inner wall of the sleeve 1 provided with its tip opened to the space of the injection molding die, A device for pressurizing and discharging a pressurized fluid from a pressurized fluid passage 3 formed by a shaft core 2 that is inserted therein and is capable of advancing and retracting in the axial direction. Using a specific shaft core 2 composed of
The distal end portion 21a of the sleeve 1 can be advanced and retracted within a specific range of the sleeve 1 to adjust the pressurized fluid passage, and at the same time,
It has been found that the object can be achieved by a pressurized fluid pressurizing / discharging device having a structure in which the front surface of the collar 22 is brought into contact with or separated from the rear end of the sleeve 1 to close / release the pressurized fluid passage. The invention has been completed.

Therefore, the gist of the present invention is as follows.
A shaft core 2 is inserted into a sleeve 1 which is opened and installed in a space of an injection molding die so as to be capable of advancing and retracting in the axial direction, and a pressure formed by an inner wall of the sleeve 1 and the shaft core 2 is applied. A pressurized fluid is pressed from the fluid passage 3 into the molten resin injected into the mold space, and the molten resin is pressed against the mold cavity surface to form a molded body having a hollow portion, and after cooling the molded body. In the pressurizing fluid press-fitting / discharging device for discharging the pressurizing fluid in the hollow portion, the sleeve 1 has a tubular portion 11 fitted in a space portion penetrating the mold and fixed to the tubular portion 11. The flange portion 12 is provided, the front end of the tubular portion 11 is opened to the mold space, the rear end is fixedly attached to the front surface of the flange portion 12, and the back side of the flange portion 12 is the collar of the shaft core 2. 22 so as to come into contact with the front surface of the mold 22, and the opening of the cylindrical portion 11 close to the mold space. Other portions 11b are of the distal end portion 11a
A pressurizing fluid port 4 connected to a pressurizing fluid source is bored at an appropriate position in a portion having a smaller inner diameter and a larger inner diameter, and the shaft core 2 includes a core body 21 and a collar 22. And the rear end of the core body 21 is fixed to the front surface of the collar portion 22.
A shaft drive mechanism 5 is continuously provided on the back surface of the core body 21.
The front end portion 21a of the sleeve 1 can be moved forward and backward between the front end portion 11a of the sleeve 1 and the other portion 11b, and pressurized fluid can pass through the inner wall of the front end portion 11a of the sleeve 1 and the front end portion 21a, but the molten resin is It is possible to form a narrow gap that cannot enter, and the operation of the shaft core drive mechanism 5 causes the head 21h of the core body 21 to protrude into the mold space during pressurization fluid pressurization. The front end of the flange 22 is inserted into the front end portion 11a, and the front surface of the flange 22 can be brought into contact with the rear surface of the flange 12.
The present invention resides in a pressurized fluid press-fitting / discharging device characterized in that a is retracted into the other portion 11b of the tubular body 11 and the front surface of the collar 22 is separable from the rear surface of the flange 12.

Hereinafter, the present invention will be described in detail with reference to the drawings, but the present invention is not limited to the examples described below as long as the gist thereof is not exceeded. 1 to 3 are
1 is a schematic cross-sectional view showing an embodiment of a pressurized fluid pressurizing / discharging device according to the present invention, FIG. 1 shows a state in which a pressurized fluid is press-fitted into a molten resin injected into a mold cavity, and FIG. FIG. 3 shows a state in which the pressurized fluid in the hollow portion of the molded body is discharged after the molten resin has been cooled and solidified, and FIG. 3 shows the shaft core 2 constituting the pressurized fluid press-fitting / discharging device shown in FIGS. 1 and 2. The preferable structure of the core body 21 of FIG. FIG. 4 is a schematic partial cross-sectional view showing another embodiment of the pressurized fluid pressurizing / discharging device according to the present invention. FIG. 5 is a schematic cross-sectional view for explaining the effect of the head portion 21h of the tip end portion of the shaft core 2 which constitutes the pressurized fluid press-fitting and discharging device according to the present invention.

1 to 5, 1 is a sleeve, 2 is an axial core, 3 is a pressurized fluid passage, 4 is a pressurized fluid port, 5 is a fluid pressure cylinder (axial center drive mechanism), and 6 is a pressurized fluid. Outlet, 1
Reference numeral 1 is a tubular portion of the sleeve 1, 11a is a tip portion of the tubular portion 11, 11b is another portion of the tubular portion 11, and 12 is the sleeve 1.
Flange portion, 13 is a cylindrical tube, 21 is a core body of the shaft core 2,
Reference numeral 1a is a tip portion of the core body 21, 21b is a central portion of the core body 21, 21c is a support portion of the core body 21, 21d is a groove, and 21h.
Is a head of the core body 21, 22 is a collar of the shaft core 2, 23 is an O-ring, 41 is a pressurized fluid conduit, 51 is a fluid pressure cylinder 5.
Cylinder, 52 is a piston of fluid pressure cylinder 5,
53 is an O-ring, 54 and 55 are working fluid conduits for the fluid pressure cylinder 5, 61 is a pressurized fluid discharge conduit, 103 is a fixed mold, 204 is a mold cavity, 205 is a molten resin, 2
06 hollows (pressurized fluid) are shown respectively.

The sleeve 1 of the pressurizing fluid pressurizing / discharging device of the present invention is composed of a tubular portion 11 and a flange portion 12, and is fitted into a space penetrating the injection molding die to form a tubular shape. It is a member installed by opening the tip of the part 11 in the mold space. The rear end of the tubular portion 11 has a flange portion 12
Is fixed to the front of the. The sleeve 1 has a function of forming a pressurized fluid passage 3 by its inner wall (including the flange portion 12) and the shaft core 2, and the back surface of the flange portion 12 is the front surface of the collar 22 of the shaft core 2. And a function of forming a contact surface with. In the example shown in FIGS. 1 and 2, the sleeve 1 is installed in the fixed mold 103 of the injection molding mold, and the tip of the tubular portion 11 is provided so as to open in the mold cavity 204. It shows an example in which the fluid press-fitting / discharging device is installed on the fixed mold side. It is not essential to install the sleeve 1 in a fixed mold as in this example, but it may be installed in a movable mold of an injection molding mold by opening it in the mold cavity. The discharging device will be installed on the movable mold side. Further, it is not essential that the sleeve 1 is installed by opening it in the mold cavity, and as long as it is installed by opening it in the mold space where the molten resin flows in, it can be installed in a space other than the mold cavity, such as a sprue or runner. You may open and install. Furthermore, it is possible to install a plurality of sleeves 1 at the positions as illustrated, and in this case, the pressurized fluid pressurizing / discharging device is installed at a plurality of corresponding positions.

In the sleeve 1, the tip portion 11a near the opening to the mold space has an inner diameter smaller than that of the other portion 11b, and a portion 11b having a larger inner diameter is provided at a proper position for the pressurized fluid. The pressurized fluid port 4 connected to the pressurized fluid source via the conduit 41 is formed. The tip portion 11a having a small inner diameter has a narrow gap (hereinafter, simply referred to as "narrow gap") between the inner wall and the core body 21 of the shaft core 2 through which the pressurized fluid can pass but molten resin cannot enter. A portion 11b that enables formation and has a large inner diameter
The inner wall and the core body 21 of the shaft core 2 enable formation of a wider gap through which the pressurized fluid can quickly pass. The axial length of the tip portion 11a is determined according to the gap width of the narrow gap, the viscosity and pressure of the molten resin injected into the mold space, the pressure of the pressurized fluid to be press-fitted, etc. Range of 1 to 50 mm, preferably 3 to 2
It is preferable that the range is 0 mm.

The rear surface of the flange portion 12 of the sleeve 1 (the surface opposite to the surface on which the rear end of the tubular portion 11 is fixed) is
It is necessary to contact the front surface of the collar 22 of the shaft core 2 and to be able to keep the rear end of the pressurized fluid passage 3 airtight. 1 and 2
In the example shown in FIG. 2, the disk-shaped flange 22 is pressed against the back surface of the thick flange portion 12 through the O-ring 23. The thickness and shape of the flange portion 12 can be arbitrarily selected as long as the end can be kept airtight.

At the opening of the sleeve portion 1 of the tubular portion 11 into the die space portion, a cylindrical tube 13 having substantially the same inner diameter as the tip portion 11a of the tubular portion 11 is provided so as to project into the die space portion. You can The cylindrical tube 13 may be provided in any form of a cylindrical tube as an extension of the cylindrical portion 11 protruding into the mold space portion or a cylindrical tube fixed to the inner surface of the mold. The former is preferable because of its simple structure. The inner surface of this cylindrical tube 13 acts as a guide surface for the pressurized fluid having been press-fitted, and is effective in favorably guiding the pressurized fluid into the molten resin. The projecting length of the cylindrical tube 13 is preferably adjusted individually by the distance between the opposing surfaces of the mold space such as the mold cavity with respect to the projecting direction, and generally in the range of 2 to 7.5 mm. Although it can be selected, it is preferable that the distance between the facing surfaces of the mold space is 1/2 or less. The shape of the cylindrical tube 13 is not particularly limited, and the inner diameter is uniform over the entire length (see FIGS. 4C and 4D), or the inner diameter is gradually increased toward the tip. (See FIG. 1 and FIG. 2) can be used, but it is preferable that the inner diameter is gradually increased toward the tip because the effect of inducing the pressurized fluid is more excellent.

A pressurizing fluid port 4 is provided at an appropriate position of the portion 11b where the inner diameter of the sleeve 1 is increased. The pressurizing fluid port 4 is mainly supplied from a pressurizing fluid source. Is also used to introduce the pressurized fluid remaining in the hollow portion of the molded body after cooling from the pressurized fluid press-fitting / discharging device to the outside. . The position where the pressurized fluid port 4 can be provided is such that the pressurized fluid port 4 can be moved even if the shaft core 21 is driven forward and backward.
There is no particular limitation as long as it is not closed or shielded by the central portion 21b of the shaft core 21 or the support portion 21c.

Shaft core 2 of the pressurized fluid pressurizing / discharging device of the present invention
Is composed of a core body 21 and a collar 22, a rear end of the core body 21 is fixedly mounted on the front surface of the collar 22 and a shaft core drive mechanism 5 is continuously connected to the rear surface. The core body 21 has a cylindrical shape,
It is a member that is inserted into the sleeve 1 so as to be able to move forward and backward with respect to the axial direction. The member and the inner wall of the sleeve 1 serve to form the pressurized fluid passage 3. Further, the collar 22 keeps the rear end of the pressurized fluid passage 3 airtight by bringing its front surface (the side on which the rear end of the core body 21 is fixed) into contact with the rear surface of the flange portion 12 of the sleeve 1. The function of releasing the rear end of the pressurized fluid passage 3 is achieved by separating it from the rear surface of the flange portion 12.

In the example shown in FIGS. 1 and 2, the core body 21 is capable of forming the narrow gap between itself and the inner wall of the tip portion 11a of the sleeve 1.
a, a central portion 21b which can form a wide gap between the inner wall of the large-diameter portion 11b of the sleeve 1 and a support portion 21c, and the longitudinal center of the sleeve 1 is formed in the sleeve 1. It is inserted with the axes aligned. In the example shown in FIGS. 1 and 2, the outer diameter of the central portion 21b is set to be the same as the outer diameter of the tip portion 21a, and the outer diameter of the support portion 21c is made larger than the outer diameter of the tip portion 21a. Is slidable along the inner wall surface of the passage 1, and as shown in FIG. 3, a plurality of grooves 21d axially communicating with each other are provided on the outer peripheral surface thereof.
The structure is such that 1d is a passage for the pressurized fluid. In addition,
FIG. 3 shows D- of the support portion 21c in the example shown in FIG.
FIG. 6A is a cross-sectional view taken in the direction of the arrow D ′, in which FIG.

The supporting portion 21c having such a structure can smoothly drive the core body 21 to move forward and backward within the sleeve 1, and is provided between the inner wall of the portion 11b of the sleeve 1 having a large inner diameter. By providing the communicating groove 21d, a substantially wide gap is formed, so that the pressurized fluid can be passed through quickly, which is preferable. However, the central portion 21b and the support portion 2
The outer diameter of 1c is not limited to the above example as long as a wide gap can be formed between the outer diameter of 1c and the inner wall of the large inner diameter portion 11b of the sleeve 1. For example, the mechanical strength does not have a problem. The tip portion 21a may be thinner than the tip portion 21a, or may be thicker than the tip portion 21a within a range in which the pressurized fluid can be quickly passed. Also, the central portion 21b and the support portion 2
The outer diameters of 1c may be different from each other, or may gradually increase from one to the other.

When the collar 22 of the shaft core 2 is brought into contact with or separated from the back surface of the flange portion 12 of the sleeve 1,
The shape and the structure of the contact surface are not particularly limited as long as the rear end of the pressurized fluid passage 3 can be kept airtight or the rear end can be released. As a specific example, it is possible to suitably use a disc having an outer shape and a structure in which the contact surface is pressed against the back surface of the flange portion 12 via a packing material such as an O-ring. The collar 22 may be installed in the space provided in the fixed mold 103 as shown in FIGS. 1 and 2, or may be installed on the outer surface of the fixed mold 103. When the collar 22 is installed in the space provided in the fixed mold 103, as a pressurized fluid discharge passage for discharging the pressurized fluid discharged into the space from the rear end of the pressurized fluid passage 3 to the outside,
It is preferable to provide a discharge port 6 and a discharge conduit 61 connected thereto.

In this shaft core (2), (a) the tip portion 21a of the core body 21 is the tip portion 1 of the tubular portion 11 of the sleeve 1.
1a, the head 21h thereof is projected into the mold space, and the front surface of the collar 22 is in contact with the rear surface of the flange portion 12 of the sleeve 1 (press-fitting position);
Between the front end 21a of the core body 21 is retracted into the portion 11b of the sleeve 1 where the inner diameter is increased, and the front surface of the collar 22 is separated from the rear surface of the flange portion 12 (discharging position). , It is necessary to be inserted so that it can move forward and backward.

In the pressurizing fluid press-fitting / discharging device of the present invention, the head portion 21h of the tip portion 21 is in the press-fitting position (a).
Is projected into the mold space, and the surface thereof acts as a guide surface for guiding the pressurizing fluid press-fitted into the molten resin. The effect of the head portion 21h will be further described with reference to FIG. 5. When the head portion of the tip portion 21 is not projected into the mold space, it is press-fitted as shown in the left side (a) of FIG. While the pressurized fluid easily leaks toward the boundary surface between the molten resin and the mold space forming surface, when the head portion 21h projects into the mold space portion, it is shown on the right side (b) of FIG. As described above, since the surface acts as a guide surface for guiding the pressurized fluid that has been press-fitted into the molten resin, the pressurized fluid that has been press-fitted is reliably guided into the molten resin.

The projecting length of the head portion 21h into the mold space is preferably adjusted individually by the distance between the facing surfaces of the mold space such as the mold cavity in the projecting direction. It is preferable that the length is approximately the same as the protruding length. Generally, it can be selected in the range of 2 to 7.5 mm, but it is preferable to set it to 1/2 or less of the facing surface distance of the mold space. Further, the shape of the head portion 21h is not particularly limited, and as shown in FIG. 4, the tip portion 21 has a columnar shape (FIGS. 4A and 4C) having substantially the same outer diameter, Although it may have a thin shape (FIGS. 4B and 4D), it is preferable that the shape gradually becomes smaller toward the tip from the viewpoint of the effect of inducing the pressurized fluid.
Examples of preferable shapes include a conical shape, a truncated cone shape, a pyramid shape, a truncated pyramid shape, and a hemispherical shape, but are not limited to these exemplified shapes.

The shaft core drive mechanism 5 of the pressurizing fluid press-fitting / discharging device of the present invention has a function of moving the shaft core 2 forward and backward between the press-fitting position (a) and the discharging position (b). is there. The shaft core drive mechanism 5 may be any one such as an air cylinder, a fluid pressure cylinder such as a hydraulic cylinder, or an electric motor drive jack as long as it has the above-mentioned functions. A suitable fluid pressure cylinder 5 is suitable. The fluid pressure cylinder 5 shown in FIGS. 1 and 2 is composed of a cylinder 51 and a piston 52 that slides in the cylinder 51 and is fixed to the back surface of the collar 22 of the shaft core 2. Is configured to be able to move forward and backward in the axial direction.

When pressurizing the pressurized fluid into the molten resin injected into the mold space, the shaft drive mechanism 5 is actuated so that the tip 21a of the core 21 is inside the tip 11 of the passage 1. , The head portion 21h thereof is projected into the mold space portion, and the front surface of the collar 22 is in contact with the rear surface of the flange portion 22 of the sleeve 1 (see FIG. 1; It is also called "state."). In this state, a narrow gap is formed between the outer surface of the tip portion 21a of the core body 21 and the inner wall of the tip portion 11a of the sleeve 1, so that a reverse flow of the molten resin, that is, a narrow gap of the molten resin is formed. It is possible to pressurize the pressurized fluid supplied from the pressurized fluid source (not shown) through the pressurized fluid port 4 into the molten resin without causing the invasion of the molten resin. The axial length and width of the narrow gap are the viscosity and pressure of the molten resin in the mold cavity,
The axial length is in the range of 1 to 50 mm, preferably in the range of 3 to 20 mm, and the gap width is 0.02 to 0.3 mm, although it is determined according to the pressure of the pressurizing fluid to be press-fitted.
Is preferably in the range of 0.05 to 0.2 mm.

When the pressurized fluid is pressed in as described above and the molten resin is pressed against the mold cavity surface to form a molded article having a hollow portion, which is cooled and then the pressurized fluid in the hollow portion is discharged, The shaft core drive mechanism 5 is operated to retract the distal end portion 21a of the core body 21 into the portion 11b of the sleeve 1 where the inner diameter of the sleeve 1 is increased, and the front surface of the flange 22 from the rear surface of the flange portion 22 of the sleeve 1. A state of being separated (refer to FIG. 2; hereinafter, this state is also referred to as “retracted state”). In this state, the tip 21a of the core 21 is
Since a wide gap is formed between the surface of the sleeve 1 and the inner wall of the tip portion 11a of the sleeve 1, the wide gap is used as a passage for pressurized fluid discharge, and the front surface of the collar 22 is separated from the sleeve 1. By using the rear end as the discharge port, the pressurized fluid in the hollow portion can be quickly discharged to the outside. The sleeve 1
The pressurized fluid discharged from the rear end can be discharged to the outside by using a gap between the fixed mold and the shaft core driving mechanism 5, but the discharge port 6 and It is preferable to provide the discharge conduit 61 because the working environment can be kept good.

Next, an example of usage of the pressurized fluid pressurizing / discharging device of the present invention will be described with reference to the drawings. The usage of the device of the present invention is as described below unless the gist thereof is exceeded. It is not limited to the example. 6 and 7 are schematic cross-sectional views showing an example of an injection molding machine in which the pressurized fluid pressurizing / discharging device according to the present invention is installed. FIG. 6 shows the injection of molten resin into the mold cavity of the injection molding machine. FIG. 7 shows a state before pressurizing fluid is press-fitted, and FIG. 7 shows a state where the pressurizing fluid is press-fitted into the molten resin injected into the mold cavity of the same injection molding machine to form a hollow portion.

6 and 7, reference numeral 10 denotes the pressurized fluid pressurizing / discharging device of the present invention described with reference to FIGS. 1 and 2 (4, 6, 54, 55, 61, 103, and 204 are 1 and 2 are common symbols.) 10
0 is an injection molding machine, 102 is a movable mold mounting plate, 104 is a movable mold, 105 is a movable mold insert, 106 and 107 are slide blocks, 108 is a slide base, 109 is a ball screw, and 110 and 111 are spacers. Block, 1
12 is a slide block driving device, 200 is an injection cylinder, 201 is an injection nozzle, 202 is a sprue, 203
Is a gate, 205 is a molten resin, 206 is a hollow portion, 300
Is a pressurized fluid supply / discharge mechanism, 301 is a cylinder, 302
Is a piston, 303 is a pressurized fluid chamber, 304 and 305 are check valves, 306 and 307 are electromagnetic switching valves, 308 is a pressurized fluid tank, and 309, 310, 311, and 312 are all pressurized fluid pipes, 313. Indicate discharge ports for the pressurized fluid, respectively.

In the molding machine shown in FIGS. 6 and 7, the pressurized fluid pressurizing / discharging device 10 of the present invention is installed in the fixed mold 103, and is formed by the fixed mold 103 and the movable mold 104. The molten resin 205 is injected into the mold cavity 204, and a pressurized fluid is pressed into the molten resin 205, or after the pressure is injected, the movable mold insert 105 is retracted to expand the mold cavity volume. It has a specific mold mechanism capable of forming a large hollow portion 206 inside the molded body by a synergistic effect of pressurizing the pressurized fluid and expanding the volume of the mold cavity. The pressurizing fluid inlet 4 of the pressurizing fluid pressurizing / discharging device 10 is connected to the pressurizing fluid pipe 311 of the pressurizing fluid supply / discharging mechanism 300, and pressurizing fluid is pressurized through the pressurizing fluid port 4. The supply line of the pressurized fluid supply / discharge mechanism 300 is used. The pressurized fluid is discharged via the pressurized fluid discharge port 6 and the pressurized fluid discharge conduit 61.
Further, the discharge of the pressurized fluid is also performed through the pressurized fluid port 4 together with the discharge line of the pressurized fluid supply / discharge mechanism 300.

In the examples shown in FIGS. 6 and 7, only one pressurizing fluid pressurizing / discharging device 10 is installed in the fixed mold 103, but a plurality of pressurizing fluid pressurizing / discharging devices 10 may be installed. The place where the is installed is not necessarily limited to the fixed mold 103, and may be an arbitrary mold space such as the movable mold 104 as long as it does not exceed the gist of the present invention.

The specific mold mechanism is provided with a movable mold insert 105 having a pair of inclined surfaces on the back side of the mold cavity forming surface, and the insert 105 contacts the inclined surfaces. It is supported by a pair of slide blocks 106, 107 having contactable and slidable inclined surfaces against the injection pressure of the molten resin. By separating these slide blocks from each other and retracting the insert 105, The volume of the mold cavity can be expanded. The pair of slide blocks are respectively screwed on both sides of a ball screw 109 in which the engraving directions of the screw threads are opposite to each other with the middle point of the entire length as a boundary, and the slide block driving device 112. With the rotation of the ball screw 109, the slide blocks on both sides slide along the slide base 108 and are separated from each other.

First, the pressurized fluid press-fitting / discharging device 10 of the present invention.
A method for pressurizing the pressurized fluid by using will be described. For press-fitting the pressurized fluid, the fixed mold 103 and the movable mold 104 are clamped, the slide blocks 106 and 107 are brought into close proximity, and the nest 105 is advanced to form the mold cavity 204 before volume expansion, This is performed after injecting the molten resin into the mold cavity 204. The molten resin is injected by injecting the molten resin from the injection cylinder 200 into the mold cavity 204 via the injection nozzle 201, the sprue 202 and the gate 203. Also,
The expansion of the volume of the mold cavity may be performed at the time of press-fitting the pressurized fluid or after the press-fitting.

When the pressurizing fluid is press-fitted, the pressurizing-fluid press-fitting / discharging device 10 is set in the "advanced state" shown in FIG.
The pressurized fluid is supplied from the supply line of the pressurized fluid supply / discharge mechanism 300 to the pressurized fluid pressurizing / discharging device 10 through the pressurized fluid port 4, and is press-fitted into the molten resin. The supply line introduces the pressurized fluid in the pressurized fluid tank 308 into the pressurized fluid chamber 303 composed of the cylinder 301 and the piston 302, and the pressurized fluid pressurized by the piston 302 is supplied to the pipe 3
A path that can supply the fluid to the pressurized fluid port 4 is provided via 10, the electromagnetic switching valve 306, and the pipe 311 connected to the pressurized fluid port 4. At this time, the electromagnetic switching valve 307 is closed.

Next, the pressurized fluid press-fitting / discharging device 10 of the present invention.
A method for discharging the pressurized fluid by using will be described. The pressurized fluid is discharged after the pressurized fluid is pressed into the molten resin injected into the mold cavity as described above to form a molded body having a hollow portion, and the molded body is cooled. When the pressurized fluid is discharged, the pressurized fluid pressurizing / discharging device 10 is set to the "retracted state" shown in FIG. 2 and can be discharged to the outside via the pressurized fluid discharge port 6 and the pressurized fluid discharge conduit 61. Further, when the fluid is also discharged from the pressurized fluid port 4, it can be discharged to the outside from the discharge line of the pressurized fluid supply / discharge mechanism 300 connected thereto. The discharge line is a pipe 311 connected to the pressurized fluid port 4 and a pipe 3
12, discharge port 313 for pressurized fluid via electromagnetic switching valve 306
It is a route that allows more release. At this time, the electromagnetic switching valve 306 is closed.

The pressurized fluid pressurizing / discharging device of the present invention can of course be used in a molding machine equipped with a mold for enlarging the mold cavity by a mechanism other than those illustrated in FIGS. 6 and 7, and does not expand the mold cavity. Although it can be used in a molding machine equipped with a mold, the pressurizing fluid pressurizing / discharging device of the present invention can quickly expel even a large amount of the pressurizing fluid press-fitted into the hollow portion, so that the molding cycle 6 can be shortened, so
Also, when it is applied to a molding machine for manufacturing a molded product having a large hollow portion as illustrated in FIG. 7, a particularly large effect is exhibited.

In the present invention, the molten resin means a raw material resin for injection molding which is injected from the injection cylinder of the injection molding machine into the mold cavity of the injection mold. The type of resin is not particularly limited as long as it can be injection-molded, and a polyolefin resin, a polystyrene resin, an ABS resin,
In addition to general-purpose plastics such as AS resin, various engineering plastics such as polyamide resin, polyester resin, and polycarbonate resin can be used. Further, in the present invention, the pressurized fluid refers to a fluid that does not react with the molten resin under the pressure and pressure conditions and is a gas or a liquid at room temperature. Specific examples thereof include inert gases such as nitrogen and argon, gases such as air, and liquids such as water. Among these, inert gases such as nitrogen having a low viscosity under use conditions are preferable.

[0038]

INDUSTRIAL APPLICABILITY The present invention has the following excellent effects, and its industrial utility value is extremely large. (1) Since the pressurized fluid pressurizing / discharging device of the present invention can prevent the molten resin from flowing back into the pressurized fluid passage, the pressurized fluid passage is not blocked by the resin, and the pressurized fluid is press-fitted and discharged. Can be done smoothly. (2) Since the pressurized fluid pressurizing / discharging device of the present invention can discharge the pressurized fluid by releasing the rear end of the pressurized fluid passage, the pressurized fluid can be discharged quickly. (3) In the pressurizing fluid pressurizing / discharging device of the present invention, the pressurizing fluid is press-fitted in a state in which the head portion of the tip end portion of the shaft core is projected into the mold space portion. Is well pressed into the molten resin. Further, when the head of the tip portion of the shaft core is gradually tapered toward the tip, this effect is further improved. (4) In the pressurizing fluid pressurizing / discharging device of the present invention, a cylindrical tube can be provided at the opening to the mold space, and the provision of this can prevent the pressurizing fluid from leaking. Can be satisfactorily pressed only into the molten resin. Further, when a cylindrical tube whose inner diameter is gradually increased toward the tip is provided, this effect is further improved. (5) When the pressurized fluid pressurizing / discharging device of the present invention is used, the pressurized fluid pressure is maintained well, there is no leakage of the pressurized fluid and no blockage during pressurizing / discharging, and the pressurized fluid is quickly expelled. Therefore, it is possible to efficiently produce a hollow molded product having a beautiful appearance.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an embodiment of a pressurized fluid press-fitting / discharging device according to the present invention, showing a state in which a pressurized fluid is press-fitted into a molten resin injected into a mold cavity.

FIG. 2 is a schematic cross-sectional view showing an embodiment of a pressurized fluid press-fitting / discharging device according to the present invention, showing a state when the pressurized fluid in the hollow portion of the molded body is discharged after the molten resin is cooled and solidified. is there.

FIG. 3 is a schematic cross-sectional view showing a preferable structure of a core body of an axial core which constitutes the pressurized fluid press-fitting and discharging device shown in FIGS. 1 and 2.

FIG. 4 is a schematic partial cross-sectional view of a sleeve, a cylindrical tube and a shaft core, showing an embodiment of a pressurized fluid press-fitting and discharging device according to the present invention.

FIG. 5 is a schematic cross-sectional view for explaining the effect of the head of the tip of the shaft core protruding into the mold space of the pressurized fluid press-fitting and discharging device according to the present invention.

FIG. 6 shows an example of an injection molding machine provided with a pressurized fluid pressurizing / discharging device according to the present invention, showing a state before injecting a molten resin into a mold cavity of the injection molding machine and pressurizing the pressurized fluid. 2 is a schematic sectional view.

FIG. 7 shows an example of an injection molding machine equipped with a pressurized fluid pressurizing / discharging device according to the present invention, in which a pressurized fluid is press-fitted into a molten resin injected into a mold cavity of the same injection molding machine as in FIG. 3 is a schematic cross-sectional view showing a state in which a hollow portion is formed by forming the hollow portion.

[Explanation of symbols]

 1: Sleeve 2: Shaft core 3: Pressurized fluid passage 4: Pressurized fluid port 5: Fluid pressure cylinder (shaft core drive mechanism) 6: Pressurized fluid discharge port 11: Cylindrical part of sleeve 1 11a: Cylindrical part 11 tip part 11b: other part of tubular part 11 12: flange part of sleeve 1 13: cylindrical tube 21: core body of shaft core 21a: tip part of core body 21b: central part of core body 21c : Supporting part of core 21 21d: Groove of supporting part of core 21 21h: Head of core 21 22: Collar of shaft core 23: O-ring 41: Conduit for pressurized fluid 51: Fluid pressure cylinder 5 Cylinder 52: Piston of fluid pressure cylinder 5 53: O-ring of fluid pressure cylinder 5 54, 55: Pipe for working fluid of fluid pressure cylinder 5 61: Pipe for discharging pressurized fluid 100: Injection molding machine 102: Mounting of movable mold Board 103: Fixed mold 104: Movable mold 105: Nest of movable mold 106, 107: Slide block 108: Slide base 109: Ball screw 110, 111: Spacer block 112: Slide block drive device 200: Injection cylinder 201: Injection Nozzle 202: Sprue 203: Gate 204: Mold cavity 205: Molten resin 206: Hollow part of molded body 300: Pressurized fluid supply / discharge mechanism 301: Cylinder 302: Piston 303: Pressurized fluid chamber 304, 305: Check valve 306 , 307: Electromagnetic switching valve 308: Pressurized fluid tank 309, 310, 311, 312: Pressurized fluid pipe 313: Pressurized fluid discharge port

Claims (4)

[Claims] 1. A shaft core 2 is inserted into a sleeve 1 opened in a space of an injection molding die so as to be able to move forward and backward in the axial direction, and by an inner wall of the sleeve 1 and the shaft core 2. From the formed pressurized fluid passage 3, a pressurized fluid is pressed into the molten resin injected into the mold space, and the molten resin is pressed against the mold cavity surface to form a molded body having a hollow portion,
In a pressurizing fluid press-fitting / discharging device that discharges the pressurizing fluid in the hollow portion after cooling the molded body, the sleeve 1 and the tubular portion 11 fitted in the space portion penetrating the die and And a flange portion 12 fixed to the cylindrical portion 11, the front end of the cylindrical portion 11 is open to the mold space, the rear end is fixed to the front surface of the flange portion 12, and the rear surface side of the flange portion 12 is formed. Is designed to contact the front surface of the collar 22 of the shaft core 2, and the tip end portion 11a of the tubular portion 11 near the opening to the mold space portion has an inner diameter smaller than that of the other portion 11b and has an inner diameter of A pressurizing fluid port 4 connected to a pressurizing fluid source is bored at an appropriate position in the enlarged portion, and the shaft core 2 is composed of a core body 21 and a collar 22, and a rear end of the core body 21. Is fixed to the front surface of the collar portion 22, and the shaft core drive mechanism 5 is connected to the back surface of the collar portion 22. Portion 21a is configured to be forward and backward between the tip portion 11a and the other portion 11b of the sleeve 1,
A narrow gap can be formed between the inner wall of the tip portion 11a of the sleeve 1 and the tip portion 21a so that the pressurized fluid can pass through but the molten resin cannot intrude. Sometimes, the head portion 21h of the core body 21 is projected into the mold space portion and the tip portion 11 of the tubular body 11 is
a front surface of the flange 22 can be brought into contact with the rear surface of the flange 12, and the distal end portion 21a of the core body 21 is retracted into the other portion 11b of the tubular body 11 when the pressurized fluid is discharged. In addition, the pressurized fluid press-fitting / discharging device is characterized in that the front surface of the collar 22 can be separated from the rear surface of the flange 12. 2. The pressurized fluid press-fitting / discharging device according to claim 1, wherein the head portion 21h of the core body 21 is gradually tapered toward the tip. 3. The opening of the sleeve 1 to the mold space,
Cylindrical tube 1 having an inner diameter almost the same as the tip portion 11a of the sleeve 1
The pressurizing fluid pressurizing / discharging device according to claim 1 or 2, further comprising: 3. 4. The pressurized fluid pressurizing / discharging device according to claim 3, wherein the inner diameter of the cylindrical tube 13 is gradually increased toward the tip.