JPS6112158B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vacuum joint, and more particularly to a vacuum joint suitable for preventing electrical insulation from deteriorating due to substances generated within a vacuum container.

Generally, providing electrical insulation to vacuum containers, vacuum piping, etc. is one of the basic vacuum technologies. Conventionally, as a method of electrically insulating a large diameter flange while maintaining airtightness, the flange itself was made of an insulating material, or an insulating ring was inserted into the sealing part (Reference: "Vacuum Technology" by Genichi Horikoshi). ” (University of Tokyo Press '76, p. 124, 125). The latter will be explained in more detail based on FIG. 1. In the figure, 1 and 2 are vacuum piping. Flanges 5 and 6 having notches for insertion of vacuum O-rings 3 and 4 are welded to opposing ends of the vacuum pipes 1 and 2, respectively.
A donut disk-shaped ring 7 made of an insulating material such as ceramic is interposed between these flanges 5 and 6 via O-rings 3 and 4, and both flanges 5 and 6 are connected to screw members. 8. However, flanges 5, 6, O-rings 3, 4
and 7 constitute an electrically insulated vacuum joint.

In addition, 9 in the figure is a collar for insulating the flanges 5 and 6 when tightening is performed with a metal screw member.

In the conventional vacuum joint configured as described above, if a contamination source such as plasma, charged particles, or high-temperature metal exists inside the vacuum pipes 1 and 2, the ring 7
There is a problem that the inner surface 7a of the inner surface 7a is contaminated with metal vapor or the like, resulting in a decrease in electrical insulation.

As a measure to prevent this insulation deterioration, a ring 17 having a cross-sectional shape as shown in FIG. 2 can be considered. With such a structure, the surfaces 17a, 17
b is not irradiated by a contamination source and insulation can be maintained.
However, on the other hand, not only does the shape become complicated and the number of processing steps increases, but also the risk of leakage increases due to the deformation of the surfaces 17c and 17d, the mechanical strength of the thin walled portion 10 becomes a problem, and the vacuum By increasing the surface of the insulator facing the
There are drawbacks such as increased gas release which may cause deterioration of the characteristics of the vacuum system.

The present invention was created in view of the current situation,
The purpose is to provide a vacuum joint whose electrical insulation is not degraded by substances generated within the vacuum container.

In order to achieve the above object, the present invention provides a vacuum joint in which an electric insulator is interposed between flanges provided at opposite ends of a vacuum piping, and the flanges are tightened by a connecting mechanism. An annular spacing material made of an electrically insulating material is interposed on the outer peripheral side of the annular space formed by both the recesses, and an annular spacing member made of an electrically insulating material is interposed on the inner peripheral side of the annular space and on the outer peripheral surface of the annular space. A center ring formed with a protrusion and slightly less thick than the spacing member is provided, and a flexible member is interposed between the protrusion of the center ring and each flange to maintain the center ring. This is characterized in that the ring is held slightly apart from each of the flanges.

The present invention will be explained below based on an embodiment shown in FIGS. 3 and 4.

In FIG. 3, 21 and 22 are vacuum pipes,
Flanges 23 and 24 are provided at opposing ends of the vacuum pipes 21 and 22, respectively. The flanges 23 and 24 are provided with recesses 25 and 26 in the circumferential direction at intermediate positions in the radial direction, and connecting holes 30 and 31 are provided in opposing positions in the outer edges, respectively.

A spacing member 27 made of an electrical insulator such as ceramic is interposed on the outer peripheral side of the annular space constituted by the recesses 25 and 26.
On the vacuum piping 21, 22 side of 7, the vacuum piping 21,
A centering ring 28 made of metal such as stainless steel and having a generally T-shaped cross section with a wide surface at the end on the 22 side, and this centering 28 and each flange 2
Flexible members 29, 29 made of O-rings made of rubber, tetrafluoroethylene, polyimide, or other plastics are disposed between 3 and 24, respectively.

A screw member 32 is inserted into the connecting holes 30, 31 of the flanges 23, 24, and the flanges 23, 24 are fixed together by the screw member 32 via an electrically insulating collar. .

In such a configuration, the vacuum seal is provided by the flanges 23, 24, the centering 28 and the flexible member 29, and the spacer 27 does not directly participate in the vacuum seal. Since the size of the spacing member 27 is larger than the wide surface portion of the centering 28, the wide surface portion of the centering 28 is isolated from at least one flange 23 or 24, and both flanges 23, 24 are insulated. Ru.

Note that normally, the flexible members 29, 29 are the same, the wide surface portion of the centering 28 is isolated from both flanges 23, 24, and the electrical insulation is shared by both flexible members 29, 29. Do it like this.

In the above configuration, contamination sources such as metal vapor fly into the vacuum joint from inside the vacuum pipes 21 and 22 through the gap between the flanges 23 and 24. Since the flying direction is regulated by the flange surface, the flanges 23, 2
4 and almost parallel beam shape. Irradiation is then limited to portion A of the centering 28, as shown in FIG. Since the centering 28 is made of metal, insulation deterioration is not a problem, and since contaminants are reflected very little from metal surfaces twice or more, the progress of contamination of the flexible member 29 is extremely slow.

As explained above, according to this embodiment, contamination by metal vapor etc. can be minimized with a simple structure, no special materials such as expensive alumina porcelain are required, and the flange is symmetrical. Can be formed.

Furthermore, since the only insulator facing the vacuum is a flexible member necessary for sealing, there are fewer vacuum-related problems such as gas release from the insulator.

Furthermore, since the spacing material does not face the vacuum,
The material can be selected based on mechanical properties and electrical insulation, and the shape is simple and easy to manufacture.

Note that the present invention is not limited to the above-described embodiments; for example, the flexible member 29 may not be an O-ring, and the centering ring 28 may be formed of an insulating material and integrated with the spacing member 27. You may.

Additionally, this joint may be used for general flanges that are not electrically insulated. In this case, the spacer 27
may be made of metal if necessary, or the centering 28 and the spacing member 27 may be integrated. In this case, it goes without saying that the collar 33 is unnecessary.

The present invention has been described above based on the preferred embodiments, but according to the present invention, electrical insulation does not deteriorate due to substances generated within the vacuum container.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a conventional example, FIG. 2 is a sectional view showing an improved conventional ring, FIG. 3 is a sectional view showing an embodiment of the present invention, and FIG. 4 is a summary of FIG. FIG. 23, 24... flange, 25, 26... recess, 27... spacing member, 28... centering, 29... flexible member, 30, 31... connecting hole, 32... screw member.

Claims (1)

[Scope of Claims] 1. A vacuum joint in which an electric insulator is interposed between flanges provided at opposite ends of vacuum piping and the joints are tightened by a connecting mechanism, in which annular recesses are formed at opposite positions of the flanges. , an annular spacing member made of an electrically insulating material is interposed on the outer circumferential side of the annular space formed by both the recesses, and a protrusion is formed on the outer circumferential surface of the inner circumferential side of the annular space. A center ring formed to be slightly thinner than the spacing member is provided, and a flexible member is interposed between the protrusion of the center ring and each flange, so that the center ring is connected to each flange. A vacuum joint characterized by being held slightly away from the 2. The vacuum joint according to claim 1, wherein the flexible member is formed of an O-ring made of rubber, tetrafluoroethylene, polyimide, or other plastic. 3. The vacuum joint according to claim 1 or 2, wherein the center ring is made of stainless steel or other metal.