JPH07299835A - Pressure fluid introducing and discharge apparatus - Google Patents

Abstract

PURPOSE:To eliminate the apprehension of the clogging with a molten resin and to guide a pressure fluid introduced under pressure into the molten resin and to discharge the pressure fluid remaining in the hollow part of a molded object within a short time. CONSTITUTION:A pressure fluid is introduced under pressure and discharged through the pressure fluid passage 3 formed by the inner wall of the passage 1 of which the leading end is opened to the space part of an injection mold and the shaft core 2 inserted in the passage 1 so as to be axially movable before and behind. The specific shaft core 2 consisting of a core body 21 and a flange 22 is used and, by moving the leading end part 21a of the core body 21 before and behind within the specific range of the passage 1, the pressure fluid passage can be regulated and, at the same time, the front of the flange 22 is brought into contact with the rear end of the passage 1 and separated therefrom to close and open the pressure fluid passage.

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 press-fitted only into 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 problems, the inventors of the present invention have found that the inner wall of the passage 1 provided with its tip open to the space of the injection molding die, A device for inserting and discharging a pressurized fluid from a pressurized fluid passage 3 formed by a shaft core 2 which is inserted into the shaft core 2 and which can be moved forward and backward with respect to the axial direction. Using a specific shaft core 2 composed of a collar 22 and a collar 22, the tip end portion 21a of the core body 21 can be moved forward and backward within a specific range of the passage 1 to adjust the pressurized fluid passage, and at the same time, the pressure fluid passage of the collar 22 can be adjusted. It has been found that the object is achieved by a pressurized fluid pressurizing / discharging device having a structure capable of closing / releasing the pressurized fluid passage by contacting / separating the front surface with the rear end of the passage 1, and completed the present invention. It was done.

Therefore, the gist of the present invention is as follows.
A shaft core 2 is inserted in a passage 1 provided to be opened in a space of an injection molding die so as to be able to move forward and backward in the axial direction.
From the pressurized fluid passage 3 formed by the inner wall of the passage 1 and the shaft core 2, the pressurized fluid is pressed into the molten resin injected into the mold space, and the molten resin is pressed against the mold cavity surface. In a pressurizing fluid press-fitting / discharging device which discharges the pressurized fluid in the hollow part after cooling the molded product, the passage 1 is bored through the mold, and the tip is the mold. It is opened in the space and the rear end can contact the front surface of the collar 22 of the shaft core 2. The tip portion 11 near the opening to the mold space has an inner diameter smaller than that of the other portion 12, and has an inner diameter. A pressurizing fluid port 4 connected to a pressurizing fluid source is bored at an appropriate position in a portion where the pressure is increased, and the shaft core 2 includes a core body 21 and a collar 2.
2, the rear end of the core body 21 is fixed to the front surface of the collar 22, and the shaft core drive mechanism 5 is connected to the rear surface of the collar 22.
The tip portion 21a of the core body 21 can be moved forward and backward between the tip portion 11 of the passage 1 and the other portion 12, and the pressurized fluid can pass through the inner wall of the tip portion 11 of the passage 1 and the tip portion 21a. The molten resin is capable of forming 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 space of the mold during pressurization fluid pressurization. It is inserted in the tip part 11 of the
The front surface of the flange 2 can be brought into contact with the rear end of the passage 1, the front end portion 21a of the core body 21 is retracted to the other portion 12 of the passage 1 when the pressurized fluid is discharged, and the front surface of the collar 22 is connected to the front portion of the passage 1. A pressurized fluid pressurizing / discharging device is characterized in that it can be separated from the rear end.

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. 2 is a schematic sectional view showing a preferred structure of the core body 21 of FIG. Figure 4
5 is a schematic partial cross-sectional view showing another embodiment of the 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 portion 21h at 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.

1 to 5, 1 is a passage, 2 is an axis, 3 is a pressurized fluid passage, 4 is a pressurized fluid port, 5 is a fluid pressure cylinder, 6 is a pressurized fluid discharge port, and 11 is a passage. 1 is the tip portion, 12 is the other portion of the passage 1, 13 is a cylindrical tube, 21
Is a core body of the shaft core 2, 21a is a tip portion of the core body 21, and 21b
Is a central portion of the core body 21, 21c is a support portion of the core body 21,
21d is a groove, 21h is a head of the core body 21, 22 is a flange of the shaft core 2, 23 is an O-ring, 41 is a conduit for pressurized fluid, 51 is a cylinder of the fluid pressure cylinder 5, 52 is a fluid pressure cylinder 5. Pistons, 53 are O-rings, 54 and 55 are conduits for working fluid of the fluid pressure cylinder 5, 61 is a conduit for discharging pressurized fluid, 103 is a fixed mold, 204 is a mold cavity, 20
Reference numeral 5 indicates a molten resin and 206 hollow portion (pressurized fluid), respectively.

The passage 1 of the pressurizing fluid pressurizing / discharging device of the present invention.
Has a cylindrical shape and has a function of forming a pressurized fluid passage 3 by its inner wall and the shaft core 2. The passage 1 is provided so as to penetrate through the injection molding die and has its tip opened to the space of the injection molding die. Figure 1
2 and FIG. 2, the passage 1 is provided in the fixed mold 103 of the injection mold by opening it in the mold cavity 204, and the pressurized fluid pressurizing / discharging device is provided on the fixed mold side of the injection mold. It shows an example installed in. The passage 1 is not necessarily provided in the fixed mold as in this example, but may be provided in the movable mold of the injection molding mold and opened in the mold cavity. In this case, the pressurized fluid is used. The press-fitting / discharging device is installed on the movable mold side. Further, it is not essential that the passage 1 is provided so as to be opened in the mold cavity, and as long as it is provided so as to be opened in the mold space where the molten resin flows in, it can be provided in a space other than the mold cavity, such as a sprue or runner. It may be opened. Further, it is possible to provide a plurality of passages 1 at the positions as illustrated, and in this case, the pressurized fluid pressurizing / discharging device is installed at the corresponding plurality of positions.

In the passage 1, the tip portion 11 near the opening to the mold space has a smaller inner diameter than the other portions 12, and the inner portion has a larger inner diameter.
It has a structure in which a pressurized fluid port 4 connected to a pressurized fluid source via a pressurized fluid conduit 41 is provided. The inner wall of the tip portion 11 having a small inner diameter and the core body 21 of the shaft core 2 form a narrow gap (hereinafter, simply referred to as a "narrow gap") through which a pressurized fluid can pass but molten resin cannot enter. The large-diameter portion 12 enables the formation of a wider gap between the inner wall of the large-diameter portion 12 and the core body 21 of the shaft core 2 so that the pressurized fluid can quickly pass therethrough. The axial length of the tip portion 11 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. 1 to
The range is 50 mm, preferably 3 to 20 mm.

The rear end of the passage 1 (opposite to the front end portion 11 opening to the mold space) is brought into contact with the front surface of the collar 22 of the shaft core 2, and the passage 1 is brought into contact with the flange 22. The rear end can be kept airtight. In the example shown in FIGS. 1 and 2, the rear end of the passage 1 is a flat surface engraved in the fixed mold 103, and the disk-shaped brim 2 is formed on this flat surface.
2 is pressed through the O-ring 23 to keep the rear end of the passage 1 airtight, but the shape of the rear end of the passage 1 is such that the rear end of the passage 1 is abutted with the collar 22. As long as it can be kept airtight, it is not limited to the example shown here, and the outer surface of the fixed mold 103 or the like can be used.

In the opening of the passage 1 to the mold space,
A cylindrical tube 13 having substantially the same inner diameter as the tip portion 11 of the passage 1 can be provided so as to project into the mold space. 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 may be individually adjusted by the distance between the opposing surfaces of the mold space such as the mold cavity in the projecting direction.
It can be selected in the range of up to 7.5 mm, but it is preferably 1/2 or less of the facing surface distance of the mold space. 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 portion 12 in which the inner diameter of the passage 1 is increased.
Is provided with a pressurized fluid port 4 at a proper position, and this pressurized fluid port 4 is mainly used for introducing the pressurized fluid supplied from the pressurized fluid source into the pressurized fluid pressurizing / discharging device. However, it can also be used to discharge the pressurized fluid remaining in the hollow portion of the molded body after cooling from the pressurized fluid pressurizing / discharging device to the outside. The position where the pressurized fluid port 4 can be provided is
Even if the shaft core 21 is driven forward and backward, there is no particular limitation as long as the pressurized fluid port 4 is not closed or shielded by the central portion 21b or the support portion 21c of the shaft core 21.

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,
A member that is inserted into the passage 1 so as to be able to move forward and backward with respect to the axial direction, and serves to form a pressurized fluid passage 3 by this member and the inner wall of the passage 1. Also,
The collar 22 keeps the rear end of the passage 1 airtight by bringing its front surface (the side where the rear end of the core body 21 is fixed) into contact with the rear end of the passage 1 and separates it from the rear end of the passage 1. By doing so, it fulfills the function of releasing the rear end of the passage 1.

In the example shown in FIGS. 1 and 2, the core body 21 has a distal end portion 21a capable of forming the narrow gap between the inner wall of the distal end portion 11 of the passage 1 and the passage 1 It has a central portion 21b capable of forming a wide gap with the inner wall of the portion 12 having a large inner diameter, and a support portion 21c, and is inserted into the passage 1 with their longitudinal central axes aligned with each other. ing. Then, in the example shown in FIGS. 1 and 2, the outer diameter of the central portion 21b is made the same as the outer diameter of the tip portion 21a, and the supporting portion 21
The outer diameter of c is made larger than the outer diameter of the tip portion 21a, the outer surface of which is slidable along the inner wall surface of the passage 1, and as shown in FIG. Groove 2
1d is provided, and the groove 21d is used as a passage for the pressurized fluid. Note that FIG. 3 is a cross-sectional view of the support portion 21c in the DD ′ arrow direction in the example shown in FIG. 2, in which (a) shows three grooves 21d on the outer peripheral surface, and (b) shows four grooves on the outer peripheral surface. This is an example in which the groove 21d is provided.

The supporting portion 21c having such a structure can smoothly drive the core body 21 to move forward and backward in the passage 1 and, between the supporting portion 21c and the inner wall of the portion 12 having the large inner diameter of the passage 1, 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 outer diameters of the central portion 21b and the supporting portion 21c are not limited to the above examples as long as a wide gap can be formed between the outer diameters of the central portion 21b and the support portion 21c and the inner wall of the portion 12 having the large inner diameter of the passage 1, and for example, the mechanical It may be thinner than the tip portion 21a within a range where there is no problem in the mechanical strength, and may be thicker than the tip portion 21a within a range in which the pressurized fluid can be quickly passed.
Further, the outer diameters of the central portion 21b and the supporting portion 21c may be different from each other, or may gradually increase from one to the other.

If the collar 22 of the shaft core 2 is capable of keeping the rear end of the passage 1 airtight or releasing the rear end when the rear end of the passage 1 is brought into contact with or separated from the rear end, The shape and the structure of the contact surface are not particularly limited. As a specific example, it is possible to preferably use a disc having an outer shape and a structure in which the contact surface is pressed against the rear end of the passage 1 through 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, the discharge port 6 serves as a pressurized fluid discharge passage for discharging the pressurized fluid discharged into the space from the rear end of the passage 1 to the outside. It is preferable to provide a discharge conduit 61 connected to this.

In the shaft core 2, (a) the tip portion 21a of the core body 21 is located in the tip portion 11 of the passage 1, the head portion 21h thereof is projected into the mold space portion, and the collar 2
When the front surface of 2 is in contact with the rear end of the passage 1 (press-fitting position), (b) the tip portion 21a of the core body 21 is retracted into the portion 12 of the passage 1 where the inner diameter is increased, and It is necessary that the front surface of the collar 22 is inserted so as to be able to move forward and backward between a state in which the front surface of the collar 22 is separated from the rear end of the passage 1 (discharging position).

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. Preferred shapes are conical, truncated cone, pyramidal,
Examples thereof include a truncated pyramid shape and a hemispherical shape, but the present invention is not limited to these exemplified ones.

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 end of the passage 1 (see FIG. 1, hereinafter, this state is also referred to as “advanced state”). Say). In this state, since 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 11 of the passage 1, a reverse flow of the molten resin, that is,
The pressurized fluid supplied from the pressurized fluid source (not shown) through the pressurized fluid port 4 can be pressed into the molten resin without causing the molten resin to enter the narrow gap. The axial length and the gap width of the narrow gap are determined according to the viscosity and pressure of the molten resin in the mold cavity, the pressure of the pressurizing fluid to be press-fitted, etc. In general, the axial length is 1 ~ 50
mm range, preferably 3 to 20 mm, gap width 0.02 to 0.3 mm, preferably 0.05 to
The range is preferably 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 tip end portion 21a of the core body 21 into the portion 12 of the passage 1 where the inner diameter is increased, and the front surface of the collar 22 is separated from the rear end of the passage 1. The state (see FIG. 2; hereinafter, this state is also referred to as “retracted state”). In this state, a wide gap is formed between the surface of the tip portion 21a of the core body 21 and the inner wall of the tip portion 11 of the passage 1. Therefore, the wide gap is used as a passage for the pressurized fluid and also as a collar. The pressurized fluid in the hollow portion can be quickly discharged to the outside by using the rear end of the passage 1 in which the front surface of 22 is separated as the discharge port. The pressurized fluid discharged from the rear end of the passage 1 is discharged to the outside by
It can be performed by using a gap between the fixed mold and the shaft core drive mechanism 5, but if the discharge port 6 and the discharge conduit 61 are bored at appropriate positions of the fixed mold, a good working environment can be obtained. It is preferable because it is maintained.

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 (4,5, 6, 54, 55, 61, and 20).
Reference numeral 4 is common to those in FIGS. 1 and 2. ), 100 is an injection molding machine, 102 is a movable mold mounting plate, 103 is a fixed mold, 104 is a movable mold, 105 is a movable mold insert, 1
06 and 107 are slide blocks, 108 is a slide base, 109 is a ball screw, 110 and 111 are spacer blocks, 112 is a slide block driving device, and 20
0 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, and 303 is a pressurized fluid. Room, 30
4, 305 are check valves, 306, 307 are electromagnetic switching valves, 3
08 is a pressurized fluid tank, 309, 310, 311, 31
Reference numeral 2 denotes a pressurized fluid pipe, and 313 denotes a pressurized fluid discharge port.

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 passage, 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: Passage 2: Shaft core 3: Pressurized fluid passage 4: Pressurized fluid port 5: Shaft core drive mechanism (fluid pressure cylinder) 6: Pressurized fluid discharge port 11: Tip part of passage 1 12: Others of passage 1 Part 13: Cylindrical tube 21: Core body of shaft core 2 21a: Tip part of core body 21b: Central part of core body 21c: Support part of core body 21d: Groove of support part of core body 21h: Head of core 21 22: Collar of shaft core 23: O-ring 41: Conduit for pressurized fluid 51: Cylinder of fluid pressure cylinder 5 52: Piston of fluid pressure cylinder 5 53: O ring of fluid pressure cylinder 5 , 55: Conduit for working fluid of fluid pressure cylinder 5 61: Conduit for discharging pressurized fluid 100: Injection molding machine 102: Movable mold mounting plate 103: Fixed mold 104: Movable mold 105: Nest of movable mold 10 , 107: Slide block 108: Slide base 109: Ball screw 110, 111: Spacer block 112: Slide block driving device 200: Injection cylinder 201: Injection nozzle 202: Sprue 203: Gate 204: Mold cavity 205: Molten resin 206: Molding Hollow part of 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: Pipe for pressurized fluid 313: Discharge port for pressurized fluid

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location B29C 49/62 7619-4F // B29L 22:00

Claims (4)

[Claims] 1. A shaft core 2 is inserted into a passage 1 opened in a space of an injection molding die so as to be able to move forward and backward in the axial direction. 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, and molded. In a pressurized fluid pressurizing / discharging device for discharging pressurized fluid in a hollow part after cooling a body, a passage 1 is formed by penetrating a mold, a front end is opened in a mold space, and a rear end is a shaft. Tsuba 22 of core 2
The front end portion 11 near the opening to the mold space has an inner diameter smaller than that of the other portion 12 and is used as a source of pressurized fluid at a proper position of the inner diameter. The pressurizing fluid port 4 to be connected is bored, and the shaft core 2 is
It is composed of a core body 21 and a collar 22, and the rear end of the core body 21 is the collar 22.
The shaft core drive mechanism 5 is continuously provided on the front surface of the core 22 and on the back surface of the collar 22, and the tip portion 21a of the core body 21 can be moved forward and backward between the tip portion 11 of the passage 1 and the other portion 12. It is possible to form a narrow gap between the inner wall of the tip portion 11 of the passage 1 and the tip portion 21a, through which pressurized fluid can pass but molten resin cannot enter. At the time of pressurizing fluid, the head portion 21h of the core body 21 is inserted into the tip portion 11 of the passage 1 with the head portion 21h protruding into the mold space portion, and the front surface of the collar 22 can be brought into contact with the rear end of the passage 1. When discharging the pressurized fluid, the front end portion 21a of the core body 21 is retracted to the other portion 12 of the passage 1, and the front surface of the collar 22 can be separated from the rear end of the passage 1. Pressurizing fluid pressurizing and discharging device. 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. A cylindrical tube 13 having an inner diameter substantially the same as that of the tip portion 11 of the passage 1 is provided at the opening of the passage 1 to the mold space. The pressurizing fluid pressurizing / discharging device described. 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.