JPH03213775A - Vacuum seal - Google Patents

Abstract

PURPOSE:To obtain the stabilized vacuum seal without the generation of leak by forming a seal part with a magnet provided in the whole periphery of the bottom face of a circumferential channel provided in a flange face, a pair of magnetic members provided in the channel so as to hold both electrodes of the magnet between them and a flat flange, and sealing the magnetic fluid in cavities between the magnetic members and the flange. CONSTITUTION:A seal part consists of a circumferential channel 5 provided so as to surround the opening of a flat flange face, a magnet 4 provided in the whole periphery of the bottom face of this channel, a pair of magnetic members 3a, 3b having a height a little lower than the depth of the channel and provided in the channel so as to hold both electrodes of the magnet between them, and a flat flange 2. The magnetic fluid 6 is sealed in cavities between the magnetic members and the flange. The magnetic fluid 6 is held by the magnetic force passing through these cavities, and stabilized vacuum seal performance without the generation of leak, even if the processing accuracy of the vacuum seal face is bad, is shown.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to vacuum sealing of a flange portion attached to a large vacuum chamber.

[Conventional technology]

Conventionally, the vacuum seal for the opening of a large vacuum chamber uses a flat flange mounting surface around the opening.

This flange installation is done by enclosing the opening on the surface and using JISB
A groove having a rectangular cross-sectional shape defined by 2406 is provided,
A rubber O-ring specified by JIS B 2401 is installed in this groove, and flange installation is performed by pressing the flange against the surface to deform the O-ring and bringing the O-ring into close contact with the bottom of the groove and the flange surface. Ta.

[Problem to be solved by the invention]

Although the above-mentioned conventional technology can relatively easily obtain a vacuum of about 10-'Pa, it is necessary to make the surface roughness of the groove bottom and flange surface with which the O-ring comes in contact with a maximum roughness of 3 μm or less. Grooves are generally machined using a lathe, which makes it easy to achieve surface roughness. However, in the case of large vacuum chambers that are difficult to machine with a lathe, or groove shapes other than circular that cannot be machined with a lathe, the grooves can be machined using an end mill or milling machine. Processing is in progress.

Due to the nature of this machining, machining marks from the cutter are likely to be formed, and it is particularly difficult to eliminate circular machining marks at the final part of the machining process. Furthermore, since the machining marks are formed across the vacuum side and the atmosphere side of the O-ring groove, there is a problem in that vacuum leaks are likely to occur.

An object of the present invention is to provide a vacuum seal that provides stable sealing performance without requiring precise processing.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a circumferential groove provided surrounding the opening of a planar flange surface, and a circumferential groove provided around the entire bottom surface of the groove so as to have both poles in the width direction of the groove. A magnet, a pair of magnetic members slightly smaller than the depth of the groove formed in the groove sandwiching both poles of the magnet, and a flat flange mounting were provided so as to face the opening and close the opening. The flat flange constitutes a seal portion, and a magnetic fluid is sealed in the gap between the magnetic member and the flange.

[Function] The flange mounting at the opening of the vacuum chamber consists of a magnet installed at the bottom of the groove provided in the opening, a magnetic material slightly smaller than the depth of the groove formed by soldering this magnet, and a flange attached to the opening of the vacuum chamber. By configuring the seal portion with the magnetic flange provided so as to cover the magnetic flange, a closed magnetic circuit is formed in which the magnet → one magnetic member → the magnetic flange → the other magnetic flange → the magnet. At this time, by sealing a magnetic fluid in the gap between the magnetic member and the magnetic flange.

The magnetic fluid is held by the magnetic force passing through this gap, and operates as a vacuum seal that isolates the vacuum side from the atmosphere side. Even if there are machining marks or undulations due to poor machining accuracy on the end face of the magnetic member or the magnetic flange face, which will serve as the sealing surface, the seal will be filled with the magnetic fluid and no vacuum leaks will occur.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 2 is a plan view showing the vacuum sealing method of the present invention, and FIG. 1 is a sectional view taken along line AA in FIG. A circumferential groove 5 surrounding the opening 8 is provided on a planar flange mounting surface 1a provided around the opening 8 of the vacuum chamber 1 made of a non-magnetic material. A permanent magnet 4 is installed at the bottom of the groove 5 so as to have both poles in the width direction of the groove 5, and a magnetic member is placed in contact with both poles of the permanent magnet 4 and has a dimension hp slightly smaller than the depth ha of the groove 5. 3a and 3b are installed. On the other hand, for flange mounting of the vacuum chamber 1, a flat flange 2 made of a magnetic material is fixed to the surface 1a with a plurality of bolts 7 in order to close the opening 8. Further, the gap between the magnetic members 3a, 3b and the flange 2 is filled with a magnetic fluid 6. With this configuration, the lines of magnetic force coming out from the N pole of the permanent magnet 4 are transmitted to the magnetic member 3a, the magnetic flange 2. A closed magnetic circuit passing through the magnetic member 3b and reaching the S pole of the permanent magnet 4 is formed. At this time, the magnetic fluid 6 sealed so as to fill the gap h between the magnetic members 3a and 3b and the magnetic flange 2 is held by the magnetic force passing through the gap h, and blocks the vacuum side and the atmosphere side. Acts as a vacuum seal. In addition, even if the machining accuracy is poor due to roughness or waviness of the groove 5 or the magnetic fluid contacting surface 2a of the flange 2, the roughness and waviness are filled with the magnetic fluid 6, so that gas flows from the atmosphere side to the vacuum side. There will be no vacuum leaks that could intrude.

FIG. 3 is a longitudinal sectional view showing another embodiment of the present invention.

A circumferential groove 5 is provided on the flange surface 2a of the non-magnetic flange 2.
is provided. A permanent magnet 4 is installed at the bottom of the groove 5 so as to have both poles in the width direction of the groove 5, is in contact with both poles of the permanent magnet 4, and has a dimension hp slightly larger than the depth ht of the groove 5.
Magnetic members 3a and 3b having the following characteristics are installed. The flange 2 is fixed to the vacuum chamber 1 made of a magnetic material with a plurality of bolts 7. A gap between the magnetic members 3a, 3b and the vacuum chamber 1 is filled with a magnetic fluid 6. With this configuration, a closed magnetic circuit similar to that of the first embodiment is formed in the seal portion, and stable vacuum sealing performance that is not affected by the machining accuracy of the flange surface can be obtained.

〔Effect of the invention〕

According to the present invention, the magnetic fluid is held on the vacuum seal surface by the magnetic force generated by the magnet installed at the bottom of the groove machined in the planar vacuum seal surface of the vacuum chamber, so that the planar vacuum seal Even if the surface is poorly processed and has scratches or undulations, it can demonstrate stable vacuum sealing performance without vacuum leaks.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing one embodiment of the present invention, FIG. 2 is a plan view showing the entire vacuum sealing part of the vacuum chamber of the present invention, and FIG. 3 is a longitudinal cross-sectional view showing another embodiment of the present invention. It is a front view. DESCRIPTION OF SYMBOLS 1...Vacuum chamber, 2...Flange, 3...Magnetic body part (not shown)

Claims (1)

[Scope of Claims] 1. A flange portion of a vacuum chamber including an opening provided in the vacuum chamber, a flange attachment portion provided in the opening, and a flange attached to the flange attachment portion, comprising: A circumferential groove is provided surrounding the opening of the flange surface, a magnet is provided so as to have both poles in the width direction of the groove over the entire circumference of the bottom surface of the groove, and a groove is formed by sandwiching both poles of the magnet. 1. A vacuum seal comprising: a magnetic member having a depth slightly shorter than the depth of the groove provided facing each other; and a magnetic fluid is sealed in a gap between the magnetic member and the flange.