JPH071103A - Gas venting device for low speed casting - Google Patents

Abstract

PURPOSE:To provide a gas venting device for low speed casting having simple structure and small size, whose opening/closing movement can stably be obtd. even in the high temp. atmosphere. CONSTITUTION:A piston 5 connected with the gas venting device 2 is arranged so as to be possible to reciprocatingly move in a valve working cylinder 4. On the wall part of the valve working cylinder, venting holes 3a, 4a are formed and a gap 9 having smaller cross sectional area than the venting hole, is formed between the inner peripheral surface of the cylinder and the outer peripheral surface of the piston 5. At the time of introducing the compressed air into a rear part chamber 8 of the cylinder, the air is vented from the venting hole through the gap, and by pressure difference generated with the difference between the introduced quantity and the discharged quantity, the piston is shifted to the valve opening direction of the gas venting valve. By this method, as sealing material, etc., is not interposed between the valve working cylinder 4 and the piston 5, the breakage of the sealing material caused by the heat is not developed, and a means for cooling the sealing material becomes unnecessary.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-speed casting degassing device, and more particularly to a low-speed casting degassing device for moving a piston by a compressed fluid introduced into a valve driving cylinder to open and close the degassing valve.

[0002]

2. Description of the Related Art In order to cast a product without cavities in injection molding such as die casting, it is necessary to discharge the gas in the mold to the maximum outside the mold. For that purpose, a gas vent valve is provided so as to communicate with the inside of the mold, the gas vent valve is opened until a predetermined time to discharge the gas in the mold, and the valve is closed to enter the mold. Prevents leakage of the filled melt.

Various methods have been proposed in the past for opening and closing the gas vent valve. For example, there is a method of utilizing the inertial force of the injected molten metal and causing the molten metal to collide with the valve head of the gas vent valve to close the gas vent valve. Besides, actual fairness 3-44
As described in JP-A-30, a valve drive cylinder and a piston that reciprocates therein are provided, and a valve stem of a gas vent valve is connected to the piston, and a piston front chamber or a rear chamber defined by the piston is provided. There is also a method of opening and closing the gas vent valve by filling the chamber with compressed fluid.

[0004]

When the former degassing apparatus utilizing inertial force is used for low speed casting,
Due to the low-speed injection, sufficient inertial force cannot be obtained for the molten metal, and the desired opening / closing operation of the gas vent valve cannot be realized. Further, in the latter degassing apparatus using compressed fluid, the mold is generally not cooled in low-speed casting, so that the mold becomes hot, so that the sealing material provided between the cylinder and the piston of the valve operating cylinder, for example, 0 The ring deteriorates due to the high temperature and the degassing valve does not work. If the mold is cooled to overcome this drawback, the structure becomes complicated and the device becomes large. Further, a sealing method (labyrinth seal) utilizing flow resistance without using a sealing material is known, but such a sealing method also has a drawback that the structure becomes complicated and the apparatus becomes large in size.

In view of the above, the present invention overcomes the above-mentioned conventional problems, does not require a sealing material, a labyrinth seal, etc., and can stably open and close the gas vent valve even in a high temperature atmosphere, and has a simple structure and a small size. An object is to provide a degassing device for low speed casting.

[0006]

In order to achieve the above-mentioned object, the present invention provides a valve body fitted in a mold, and a movably provided inside the valve body. In the valve operating cylinder connected to the valve body and supplied with compressed fluid, and connected to the gas releasing valve in the valve operating cylinder by the compressed fluid. A degassing device for low-speed casting, which has a piston that defines a valve operating cylinder inner space into a cylinder front chamber and a cylinder rear chamber, and that opens and closes the gas vent valve by reciprocating motion of the piston. In (a), an exhaust hole for communicating the cylinder front chamber with the outside of the mold is formed through the valve operating cylinder, and (b)
A gap having a cross-sectional area smaller than the cross-sectional area of the exhaust hole is formed between the outer circumference of the piston and the inner circumference of the valve operating cylinder, and (c) the piston is attached in the valve closing direction of the gas vent valve. A slow casting degassing apparatus is provided in which a heat resistant piston biasing means is provided within the valve actuation cylinder.

[0007]

According to the degassing apparatus for low speed casting of the present invention having the above-mentioned structure, when the compressed fluid is supplied to the rear chamber of the cylinder, the fluid passes through the gap and flows into the front chamber of the cylinder, and the exhaust hole is formed. Exhausted from. Here, since a predetermined pressure difference, which is a difference between the amount of compressed fluid flowing in and the amount of compressed fluid discharged, is maintained before and after the piston, the pressure difference causes the piston to degas by overcoming the urging force of the piston urging means. Move in the valve opening direction. When the supply of the compressed fluid to the rear chamber of the cylinder is stopped, the piston moves in the valve closing direction of the gas vent valve by the urging force of the urging means.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A degassing apparatus for low speed casting according to an embodiment of the present invention will be described with reference to FIG. A flange portion 1A having an opening is provided at one end of the valve body 1, and the opening forms a valve seat 1a on which the valve head 2A of the gas vent valve 2 can be seated. Further, a through hole 1c forming a gas vent passage is formed in the tubular portion of the valve body 1, and a male screw 1b is formed on the outer peripheral surface of the other end.
Is screwed. A cylindrical valve guide 3 which is fitted to the inner peripheral surface of the valve body 1 and guides the reciprocating movement of the gas vent valve 2 is provided coaxially with the valve body 1. The valve guide 3 has an exhaust hole 3a formed therethrough for discharging a compressed fluid such as compressed air.

On the outer peripheral side of the valve guide 3, a substantially cup-shaped valve operating cylinder body 4 is fixed. A female screw 4b which is screwed into the male screw 1b is screwed on the inner peripheral side of one end of the cylinder body 4, and an exhaust hole 4a is formed at the same position as the exhaust hole 3a. Further, a compressed air supply port 4c connected to a compressed air supply source (not shown) is formed through the bottom of the cylinder body 4. A space defined by the valve guide 3 and the inner peripheral surface of the cylinder body 4 becomes a valve drive cylinder space.

The valve rod 2B of the gas vent valve 2 extends into the valve drive cylinder space, and a piston 5 is fixed to the tip of the valve rod 2B by a mounting screw 6. The piston 5 allows the valve drive cylinder space to be a cylinder front chamber 7 and a cylinder rear chamber 8.
And the exhaust holes 3a, 4a are defined in the cylinder front chamber 7
The compressed air supply port 4c communicates with the cylinder rear chamber 8. Further, in the cylinder front chamber 7, a heat resistant compression spring 10 for urging the piston 5 toward the cylinder rear chamber 8 (the closing direction of the gas vent valve 2) is provided with the valve rod 2B.
It is installed around.

Here, the outer diameter of the piston 5 is set to be slightly smaller than the inner diameter of the cylinder body 4, so that a small annular gap (compressed air) is formed between the outer peripheral surface of the piston 5 and the inner peripheral surface of the cylinder body 4. An exhaust gas gap 9 is formed. The cross-sectional area of the annular gap 9 is smaller than the cross-sectional area of the exhaust holes 3a and 4a. The size of the compressed air exhaust gap 9 is determined by the relationship between the amount of compressed air flowing into the cylinder rear chamber 8 and the amount discharged from the exhaust holes 3a and 4a.
It is appropriately determined so that the amount of compressed air that flows in is larger than the amount of compressed air that is discharged. Further, in order to reliably open the gas vent valve 2 against the elastic force of the heat resistant compression spring 10,
The gap length in the radial direction is preferably about 0.03 mm.

In the above structure, the compressed air supply port 4c
When compressed air is supplied to the cylinder rear chamber 8 through the compressed air, the compressed air acts on the piston 5. Further, the compressed air passes through the annular gap 9 between the cylinder body 4 and the piston 5,
It flows into the cylinder front chamber 7 and is exhausted from the exhaust holes 3a and 4a. Here, a predetermined pressure difference (difference between the amount of compressed air flowing in and the amount of compressed air discharged) is maintained before and after the piston 5. The pressure difference overcomes the urging force of the compression spring 10 and the piston 5 moves toward the cylinder front chamber 7, so that the valve head 2A of the gas vent valve 1 separates from the valve seat 1a and is in the valve open state. When the supply of compressed air to the cylinder rear chamber 8 is stopped, the piston 5 moves toward the cylinder rear chamber 8 by the urging force of the heat resistant compression spring 10, and the gas vent valve 1 is closed. The present invention is not limited to the above-described embodiments, and various modifications and improvements can be made within the scope of the technical matters described in the claims.

[0013]

According to the degassing apparatus for low speed casting of the present invention described in detail above, a structure is used in which a seal material is not used between the cylinder and the piston of the valve actuating cylinder, and the pressure difference before and after the piston is maintained. Since the gas release valve is operated by the pressure difference and the heat-resistant compression spring, stable valve operation is possible even in a high temperature atmosphere. Since no sealing material is provided and no special sealing method structure is used, cooling is not required, the structure is simplified, and the device can be downsized.

[Brief description of drawings]

FIG. 1 is a sectional view showing a degassing device for low speed casting according to a first embodiment of the present invention.

[Explanation of symbols]

 1 Valve body 2 Gas vent valve 3a, 4a Exhaust hole 4 Valve drive cylinder cylinder body 5 Piston 9 Annular gap 10 Heat resistant compression spring

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[Procedure amendment]

[Submission date] August 3, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

In the above structure, the compressed air supply port 4c
When compressed air is supplied to the cylinder rear chamber 8 through the compressed air, the compressed air acts on the piston 5. Further, the compressed air passes through the annular gap 9 between the cylinder body 4 and the piston 5,
It flows into the cylinder front chamber 7 and is exhausted from the exhaust holes 3a and 4a. Here, a predetermined pressure difference before and after the piston 5 ( depending on the difference between the amount of compressed air flowing in and the amount of compressed air discharged)
Occurs ) is maintained. The pressure difference overcomes the urging force of the compression spring 10 and the piston 5 moves toward the cylinder front chamber 7 so that the valve head 2A of the gas vent valve 1 is moved to the valve seat 1
The valve is opened apart from a. In addition, the cylinder rear chamber 8
When the supply of compressed air to the
The piston 5 moves toward the cylinder rear chamber 8 by the urging force of, and the gas vent valve 1 is closed. The present invention is not limited to the above-described embodiments, and various modifications and improvements can be made within the scope of the technical matters described in the claims.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hitoshi Ishida Ryobi Co., Ltd. 762, Mezaki-cho, Fuchu-shi, Hiroshima

Claims (1)

[Claims] 1. A valve body fitted into a mold, and a degassing valve movably provided in the valve body for selectively communicating the inside of the mold with the outside of the mold through the valve body. A valve operating cylinder connected to the valve body and supplied with a compressed fluid; and a valve operating cylinder connected to the degassing valve and movable in the valve operating cylinder by the compressed fluid. And a piston defining a rear chamber of the cylinder, and a reciprocating motion of the piston opens and closes the gas vent valve for low-speed casting. In the valve operating cylinder, the cylinder front chamber and the mold An exhaust hole communicating with the outside is formed through, and a gap having a cross-sectional area smaller than the cross-sectional area of the exhaust hole is formed between the outer circumference of the piston and the inner circumference of the valve operating cylinder. Degassing A low-speed casting degassing device, characterized in that heat-resistant piston urging means for urging the valve in the valve closing direction is provided in the valve operating cylinder.