JP2000120887A - Sealing structure for gate valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing structure of a gate valve whose gasket ring can easily be attached between a valve casing and a valve casing cover. SOLUTION: In this gate valve, a valve casing cover 28 is arranged for covering an upper end opening of a valve casing 22. The openings of the valve casing 22 and the valve casing cover 27 have elliptic forms. A valve casing flange 30 of the valve casing 22 is abutted against a cover flange 31 of the valve casing cover 27. In such a case, the valve casing 22 is casted by precision casting using a sublimation pattern, to form an elliptic groove-like recession 32 on the abutting surface of the valve casing flange 30, along a peripheral edge of the opening. A gasket ring 33 which is in press-contact with the abutting surface of the cover flange 31 is arranged in the recession 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing technique between a valve box and a valve box lid of a gate valve, and more particularly to a sealing structure of the gate valve.

[0002]

2. Description of the Related Art A conventional gate valve is provided with a valve box cover 2 covering an upper opening of a valve box 1 as shown in FIG.
A valve body 4 for opening and closing the port 3 of the valve box 1 is arranged in a vertically movable manner, and a valve rod 5 for driving the valve body 4 up and down is rotatably supported by the valve box cover 2 and the packing pressing cover 6. I have. The valve case lid 2 abuts on the valve case flange portion 8 of the valve box 1 at the cover flange portion 7, and a gasket ring 10 is disposed in a groove-shaped recess 9 formed on the contact surface of the cover flange portion 7. With lid flange 7 and valve box flange 8
The seal is between.

[0003]

The recess 9 for disposing the gasket ring 10 is provided on the lid flange 7.
The reason for forming on the contact surface is its workability.

Since the openings in the valve case 1 and the valve case cover 2 are oblong along the cross-sectional shape of the valve body 4, the groove-shaped recess 9 is formed along the periphery of the opening of the valve case 1 and the valve case cover 2. It must be formed in an oval shape. The recess 9 is machined after casting.
In the case where is formed, the processing operation becomes complicated. Therefore, the groove-shaped concave portion 9 is formed by casting. It is easier to perform the operation on the small lid flange 7.

However, when the groove-shaped concave portion 9 is formed in the lid flange portion 7, the gasket ring 10 disposed in the concave portion 9 falls off during the operation of assembling the valve box lid 2 to the valve box 1. However, there is a problem that the assembling work takes time. In addition, when the valve box cover 2 is removed at a site or the like, it is difficult to securely mount the gasket ring 10 because there is no auxiliary jig or the like.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a seal structure of a gate valve in which a gasket ring can be easily mounted between a valve box and a valve box cover.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a sealing structure of a gate valve according to the present invention comprises a valve box cover covering an upper end opening of a valve box, and a valve box and a valve box cover. The opening is oval, and the valve box is cast by precision casting using a vanishing model at the gate valve where the valve box flange of the valve box and the cover flange of the valve box cover come into contact. An elliptical groove-shaped concave portion is formed on the contact surface of the flange portion along the periphery of the opening, and a gasket ring that presses against the contact surface of the lid flange portion is arranged in the concave portion.

According to the above-described structure, by forming a recess in the valve box flange by precision casting using a vanishing model, it is not necessary to provide a draft in the recess, and the gap between the opposed inner surfaces of the recess is uniform. As a result, the surface pressure between the inner surface of the concave portion and the gasket ring becomes uniform, and a reliable sealing property is obtained. In addition, since the recess is present in the flange of the valve box, the valve box cover can be overlapped with the gasket ring arranged in the recess when the valve box cover is assembled to the valve box. The gasket ring can be easily and accurately assembled without falling off during the assembly operation.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1 and FIG.
Has a valve element 24 disposed in the valve box 22 in a direction crossing the flow path 23 in the valve box. The valve element 24 can be freely moved between the flow path 23 in the valve box and the valve element storage space 25. Provided. The valve body storage space 25 is formed by a valve body storage part 26 of the valve box 22 and a valve box cover 27 which is arranged so as to cover the upper end opening of the valve body storage part 26. A packing holding lid 28 is provided.

The lower end of the valve stem 29 is screwed into a female screw top (not shown) mounted on the valve body 24, and the upper end of the valve stem 29 is covered with the valve box cover 27.
Is rotatably held. The valve box 22 and the valve box cover 27
The valve box flange portion 30 provided on the outer peripheral edge of the upper end of the valve body housing portion 26 and the lid flange portion 31 provided on the outer peripheral edge of the lower end of the valve box cover 27 are in contact with each other. The contact surface has an oval groove-shaped concave portion 32 along the periphery of the opening, and a gasket ring 33 that presses against the contact surface of the lid flange portion 31 is arranged in the concave portion 32. The recess 32 is cast-formed without processing by casting the valve box 22 by precision casting using a vanishing model. Examples of precision casting using the vanishing model include a full mold method and a lost wax method.

With the above-described configuration, the concave portion 32 cast using the vanishing model does not need to have a draft,
The gap between the opposing inner surfaces of the recess 32 becomes uniform, the surface pressure between the inner surface of the recess 32 and the gasket ring 33 becomes uniform,
Assured sealing performance is obtained.

In addition, since the recess 32 is present in the valve box flange 30, the gasket ring 33 is inserted into the recess 32 before assembling the valve box cover 27 to the valve box 22.
In the state where the gasket ring 33 is arranged, the valve box lid 27 can be overlapped with the gasket ring 33, so that the gasket ring 33 does not fall off during the assembling work as in the conventional case, making the work easy and accurate. Gasket ring 33
Can be attached, and leakage due to a failure in mounting the gasket ring 33 can be prevented.

[0013]

As described above, according to the present invention, since the concave portion is formed by casting with a vanishing model, there is no draft in the concave portion, the gap between the opposing inner surfaces of the concave portion is uniform, and the concave portion is formed. The surface pressure between the inner surface and the gasket ring becomes uniform, so that reliable sealing performance can be obtained. In addition, since the recess exists in the flange of the valve box, the valve box lid can be overlapped with the gasket ring previously arranged in the recess and assembled to the valve box, and the gasket ring falls off during the assembly work. The gasket ring can be assembled easily and accurately without any trouble.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a valve according to an embodiment of the present invention.

FIG. 2 is a plan view of a valve box in the valve.

FIG. 3 is a sectional view showing a conventional valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Gate valve 22 Valve box 23 Valve box flow path 24 Valve element 25 Valve element storage space 26 Valve element storage part 27 Valve box cover 28 Packing holding lid 29 Valve rod 30 Valve box flange 31 Lid flange 32 Concave 33 Gasket ring

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshimitsu Kuraya 1-1-1, Nakamiya Oike, Hirakata City, Osaka Prefecture Inside Kubota Hirakata Plant Co., Ltd. (72) Inventor Junji Takehara 1-1-1, Nakamiya Oike, Hirakata City, Osaka Prefecture No. 1 Inside Kubota Hirakata Plant (72) Inventor Takayuki Miyazaki 1-12-19 Kitahorie, Nishi-ku, Osaka-shi, Osaka F-term in Kurimoto Iron Works Co., Ltd. 3H053 AA26 AA35 BC14 DA02

Claims (1)

[Claims] 1. A valve box cover is disposed so as to cover an upper end opening of a valve box, and the openings of the valve box and the valve box cover form an oval. In the gate valve that abuts, by casting the valve box by precision casting using a vanishing model, to form an oval groove-shaped recess along the opening periphery on the contact surface of the valve box flange, A seal structure for a gate valve, wherein a gasket ring is provided in the recess to press against the contact surface of the lid flange.