JPS6136011Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a fastening structure for fastening flanges and the like in pipes, containers, etc. that require electrical insulation.

For example, when assembling and configuring vacuum vessels and tubes used in nuclear fusion experimental equipment, it is necessary to maintain electrical insulation between each part.

FIG. 1 shows a fastening structure that is commonly used in the past in such cases.

In Figure 1, 01 is a bolt, 02 is a nut, 03
is the upper washer, 04 is the lower washer, 05 is the flange of the container, 06 is the same flange, 07 is the insulating ring, 08 is the insulating bushing, 09 and 010 are the sealing materials, and the flange 05 is formed by the insulating ring 07 and the insulating bushing 08. and flange 06 is maintained.

For mechanisms that use ceramic with good insulation for insulation ring 07 and insulation bush 08, sealing material 09, 010 is used.
If a tightening force is applied to the insulating bushing 08, a large force will be applied to the neck of the insulating bushing 08, which may cause damage. Another drawback was that the bolt 01 moved and came into contact with the tip of the insulating bush 08, causing a crack there.

The present invention has been made in consideration of the above-mentioned circumstances, and its object is to provide a fastening structure which prevents the occurrence of localized excessive stress in the insulating bushing by increasing the inner diameter of the force transmission surface of the washer which transmits the tightening force of the bolt to the insulating bushing.

Hereinafter, the present invention will be explained based on the illustrated embodiments.

In FIG. 2, flanges 3 and 5 are arranged on both sides of an annular insulating member, that is, an insulating ring 1, and the through holes 7 of the insulating ring 1 and the through holes 9 and 11 of the flanges 3 and 5 are as shown in the figure. A fastening bolt 13 is aligned and extends through the through holes 7, 9, 11, and a washer 17 is interposed between the flange 3 and a nut 15 screwed onto the tip thereof.

An annular groove is cut into the surfaces of the flanges 3 and 5 that are in contact with the ring 1, and O-rings 19 and 2 are inserted into the annular groove.
1 is filled to prevent gas flow through that area.

A flange is attached to the shoulder surface of an insulating bushing 25 made of ceramic and having a sleeve portion 23 extending into the through holes 11 and 7 almost to the center of the ring 1 through a thin washer 27 made of soft metal, that is, copper. It is in contact with the outer surface of 5.

A comparatively thick washer 33 is sandwiched between the head of the bolt 13, which has a reduced diameter portion 29 formed approximately in the center, and the insulating bushing 25, and its fastening force acting surface 35 contacts the insulating bushing 25 via a thin washer 27.

A relatively large annular cavity 37 is cut into the inner end surface of the washer 33 surrounding the hole through which the bolt 13 passes, and the inner diameter of the tightening force acting surface 35 is kept larger than the diameter of the through hole 11.

In the above configuration, the tightening force generated by turning the nut 15 is transmitted to the flange 3 via the washer 17, and is also transmitted to the flange 5 via the washer 33, washer 27, insulating bushing 25, and washer 27, and is transmitted to the flange 5 via the washer 33, washer 27, insulating bushing 25, and washer 27, and is The rings 19, 21 are pressed against the insulating ring 1 and the flanges 3, 5 are tightly fastened.
The insulating ring 1 and the insulating bushing 25 prevent conduction of electricity from the flange 3 to the flange 5.

Uneven contact between the insulating bushing 25 and the flange 5 and the washer 33 due to manufacturing errors is alleviated by the deformation of the washer 27.

According to the embodiment described above, the inner diameter of the tightening force acting surface 35 of the washer 33 is made larger than the diameter of the through hole 11, and uneven contact is prevented by deforming the copper washer 27, so that the insulating bushing 25 can resist compressive force. The bolts 13
Even if it moves slightly, it does not contact the sleeve portion 23 and no excessive stress is generated.

That is, even if the insulating bushing 25 having the sleeve portion 23 is made of ceramic, excessive bending stress is not generated, and the insulating performance can always be maintained at a high level without being damaged.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of a conventional device, and FIG. 2 is a sectional view showing an embodiment of the present invention. 1... Insulation ring, 3, 5... Flange, 7, 9,
11...Through hole, 13...Bolt, 15...Nut, 2
5... Insulating bushing, 33... Washer, 35... Working surface,
37... Blank space.

Claims (1)

[Scope of utility model registration request] A metal flange member disposed parallel to each other in contact with each side of the insulating ring, a bolt passing through a through hole drilled in alignment with the flange member and the insulating ring, and fitting into the neck of the bolt. and an insulating bushing having a sleeve portion extending into the through hole, a nut screwed onto the tip of the bolt, and a washer held between the head of the bolt and the bushing, the washer An electrically insulating fastening structure characterized in that an inner diameter of a surface in contact with the bushing is larger than a diameter of the through hole.