JPS58166168A - Bellows - Google Patents

Abstract

PURPOSE:To obtain a multiply-connected bellows which is excellent in its strength and airtightness and free from abnormal vibration or stress at the time of high-speed operation, by superposing end portions of unit bellows on each other, and coupling them together by radiating a laser beam onto the same. CONSTITUTION:Unit bellows 9a, 9b to be connected are fitted on a copper cylinder 20 manufactured to have a diameter suited for the inner diameter of the bellows, and end portions 21a, 21b of the bellows 9a, 9b are superposed on each other. The cylinder 20 is supported on a base 22 in a freely rotatable manner and it is turned by a driving unit 23. A laser beam 25 is emitted from a laser beam source 24 and focused onto the end portions 21a, 21b of the bellows 9a, 9b.

Description

Detailed Description of the Invention (a) Description of the Technical Field The present invention relates to a bellows9, and particularly relates to a multi-jointed bellows in which a plurality of bellows are joined in multiple stages to form a long bellows◇ (b) Description of the prior art Generally, bellows have a limit on the length of each bellows due to the manufacturing method, or because long bellows are more likely to buckle during compression. When a bellows with a larger size is required, it is often used as a multi-stage jointed bellows by joining individual bellows by welding etc. Figure 1 shows a vacuum valve of a so-called vacuum breaker that interrupts current in a vacuum. The structure is shown when using a multi-step bellows. As shown in Fig. 1, a general C-2 vacuum valve is a high-vacuum container consisting of an insulating capacity 161 made of a seven-story building or on an insulating material such as glass, a fixed end plate 2, and a movable end plate 3. A fixed electrode 5 fixed to a fixed electric shaft 4 serving as an electric path and a movable electrode 7 fixed to a movable current-carrying shaft 6 serving as an electric path are arranged facing each other.
is held by the bearing 8 so that it can move in the axial direction.Also, in order to be able to move the movable current-carrying shaft 6 while maintaining the inside of the vacuum pulp container at a high vacuum, the bearing 8 and 1j8m between the movable current-carrying shafts 6 is a bellows 9
It's closed. Both ends of the bellows 9 have one end fixed to the flange 101 on the movable current-carrying shaft 6, and the other end sealed to the bellows receiver 11 provided on the movable end plate 3 by brazing. The bellows end of the bellows end plate has a structure that allows it to move to zero with respect to the movable energizing shaft 6.

Finally, the higher the pressure resistance of the vacuum valve, the faster the opening speed and the longer the stroke in order to minimize contact wear due to melting during opening. Therefore, for example, Figure 1C
In the vacuum valve shown in FIG.
It is joined at 12b, and the expansion and contraction stroke is increased by nine points.

When joining multi-stage spliced bellows with such a structure, it is difficult to directly join the bellows together because the bellows are extremely thin plates and it is difficult to control the amount of melting using conventional resistance welding. Generally, when joining such thin plates together by welding (1), as shown in Fig. 2, the workpiece 13 is
A method called edge arc welding is used in which the end faces 13c of the m$13b are aligned and overlapped, and then they are melted and joined using a TIG welding torch 14 while shielding with an inert gas 15. FIG. 3 shows a cross-sectional view of a bellows made into a two-step joint by edge arc welding, showing a case in which unit bellows 9a and 9b are connected at a seam 16. A disadvantage of the bellows connected in the manner shown in Fig. 3 is that when the bellows is expanded, the inner side of the seam 16 deforms as if torn as shown in Fig. 4, which generates high stress and reduces the strength. The problem is that it is not possible to obtain bellows that are soft and long. Therefore, a structure as shown in FIGS. 5 and 6 is adopted in a high-voltage vacuum valve. That is, the end 17 of the unit bellows 9a and 9b
a, 17b 1m chips 18a, 18b are fixed by edge arc welding. Thereafter, as shown in FIG. 6, the tops 19 of the tips 18a and 18b are edge arc welded. In this way, the direction of the gap at the end 17 is not perpendicular to the direction of force action, but is parallel to it, so it is possible to avoid the tearing mode deformation as shown in Figure 4. Moreover, since the top part 19 of the chip 18 placed under the deformed shade as shown in FIG. 4 can have any thickness, it can be sufficiently melted and strong welding can be achieved.

The structure in which the tip is manually joined between the bellows as described above is clever and has a considerable effect. However, because it requires extra man-hours to process and join the chips, and because there is a chip that has a larger mass than the one pipette between the bellows, the expansion and contraction between each unit bellows is not synchronized during high-speed operation, resulting in abnormal stress. Another problem is that it tends to cause abnormal vibrations. For these reasons, it is preferable that the original shape of the bellows does not have too sudden a change in cross section.

(C) Purpose of the Invention The present invention eliminates the above-mentioned drawbacks and provides a bellows with excellent strength and characteristics by joining each unit bellows in a smooth shape in a multi-stage jointed bellows. It's about doing.

(d) Structure and operation of the invention FIG. 7 is an explanatory diagram showing the configuration of one embodiment of the present invention.

The unit bellows 9a*9b to be connected is fitted into a copper cylinder 20 manufactured to match the inner diameter of the bellows, and the end portion 21m of the bellows to be joined is fitted.
, 21b are mounted one on top of the other. The cylinder 20 is a support base 22
The drive unit 23 is supported in such a way that it turns when the
It can be rotated by Laser light 25 is emitted from the laser light source 24, and the end portion 2 of the bellows is
13. The focus should be on 21b. Further, the cylinder 20 is pressed against the back side so that the end portions 21a and 21b are in close contact with each other.The cylinder is made of steel, which is a material that has good thermal conductivity and poor weldability with the part to be welded.

Laser light has high-density energy and can be locally melted by narrowing its focus. According to this embodiment, the bellows made of thin plates are connected in a stacked plate joint shape as shown in Fig. 7 above. can do.

(e) Effects of the Invention FIG. 8 is a detailed view of a cross section of the joint part of the multi-step jointed bellows joined in this embodiment. The end portions 218#21b of the unit bellows 9a+9b are firmly connected by a weld metal 26 formed by laser beam irradiation, and are joined without any discontinuity on the circumference, so that sufficient airtightness is maintained. When the bellows expands and contracts, such joints are
') j r? ] A shearing force acts, but no force in the YY direction causes a tearing mode of deformation. Also,
In the joint cross section shown in FIG. 8, the thickness T of the bellows and the width of the weld metal 26 are approximately equal, so the stress line 27
The flow is smooth, forming a shape that allows stress to flow smoothly. Further, in FIG. 8, the back side of the welded part, which is generally prone to deterioration in shape due to drooping of molten metal, is in close contact with the cylinder 201, so that the shape is corrected and formed smoothly. Therefore, the bellows of this embodiment is resistant to fatigue failure even when it is compressed, expanded and contracted, and has a structure that is strong in maintaining airtightness.

In FIG. 1, the seven flange 10 or the bellows receiver 11 and the bellows end 21a are joined by brazing by forming a brazing layer 28 as shown in FIG. Even though a vacuum is maintained, processing of brazing filler metal requires careful processing to ensure airtightness, and requires linear inspection work. Further, the brazing layer is scattered with pores such as pinholes, which trap gas, which causes a problem in the degree of vacuum. In another embodiment of the present invention, the bellows 9 and the bellows receiver 11 are joined by laser welding to form a weld metal 26 as shown in FIG. A highly reliable vacuum valve can be obtained with a strength characteristic of 9.

Next, in laser welding, the objects to be welded must be welded in such a way that there are no gaps between them, but in the embodiment shown in FIG. Therefore, in another embodiment of the present invention, a wheel 30 is provided on the nozzle 29 of the laser welding machine as shown in FIG.
, 21b are pressed between the wheel 30 and the cylinder 20 before welding is performed by irradiating the laser beam 25. Therefore, good welding can be performed without creating a gap between the objects to be welded.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing the structure of a vacuum valve using multi-jointed bellows, Fig. 2 is an explanatory drawing showing the edge arc welding method, Figs. 3, 4, 5, and 61! iIO is a cross-sectional view showing a conventional multi-step bellows joining method, FIG. 7 is an explanatory view showing an embodiment of the present invention, FIG. 8 is a cross-sectional view showing the effects of the present invention, and FIGS. 9 and 10. 11 is a sectional view showing a conventional method of joining a bellows and a bellows receiver and a joining method according to another embodiment of the present invention, and FIG.
FIG. 7 is a front view showing another embodiment according to the present invention. 9...Multi-stage joint bellows 9a+9b*9c ・'-Single unit clause 11...Bellows receiver 20...Cylinder 218.21b...End portion of bellows 25...Laser light 30...Wheel (7317) Agent Patent Attorney Noriyuki Chika
(1 other person) Figure 1 Evening Figure 2 Figure 3 Figure 4 /A Figure 5 Figure 6 Figure 17α /7.5 Figure 7 □2 draw 2 Figure 8 0 Figure 9 Figure 10 Figure 111 !1 -38' [-

Claims (1)

[Claims] A multi-stage jointed bellows formed by joining a plurality of unit bellows, characterized in that the end portions of each of the unit bellows are overlapped and joined by irradiating a laser beam thereon◎