JPH033828B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for attaching a flange to a bellows used in an expansion pipe joint or a flexible joint.

[Prior Art] Expansion pipe joints and flexible joints absorb thermal expansion and bending loads when pipes and the like are subjected to them, and bellows having an accordion shape are often used.

Both ends of the bellows are usually provided with flanges,
Piping can be connected to this flange. Furthermore, when the flow velocity of the internal fluid increases, vibrations and turbulence occur in the bellows, so expansion pipe joints have also appeared in which an inner cylinder is provided inside the bellows to improve stability.

Conventionally, the bellows and the flange have been attached by welding, and other methods have also been adopted in which the bellows is fitted into the flange by crushing a portion of the crest of the bellows.
Further, the other end of the inner cylinder is left free, that is, in an unfixed state so as not to interfere with the expansion and contraction operation of the bellows.

[Problems to be solved by the invention] However, in the case of the installation method by welding, thermal deformation due to welding, pinholes in the welded part, etc.
There is a risk that cracks may occur, and in the case of a fitting means in which the bellows have flattened peaks, there is a problem that sufficient bonding strength cannot be obtained between the bellows and the flange.

Furthermore, in the case of a bellows having an inner cylinder, both ends of the inner cylinder are either welded or fitted into the bellows through packing. However, in the case of welding, the same problem as mentioned above occurs, and in the latter case, there is a risk of fluid leaking from the packing part, and in the case of vertical piping, the other end is free, so the inner cylinder may fall during construction. There are drawbacks that make it easier.

[Object of the Invention] The present invention has been made in view of the above circumstances, and its purpose is to provide a method for attaching flanges to a bellows, which can firmly connect flanges to both ends of the bellows, regardless of the presence or absence of an inner cylinder. It's about doing.

[Means for achieving the object] In order to achieve the above object, the bellows flange attachment method of the present invention includes inserting a bellows having a straight pipe portion into a first core bar and fixing the bellows with a first mold. a step of fitting a flange to the straight pipe portion and supporting it with a first mold; closing the end of the bellows with a second core metal, and closing the end of the bellows with the first and second core metals. forming a sealed space inside the straight pipe section; fixing the end of the bellows with a second mold placed at a predetermined distance from the first mold; The method includes the steps of introducing high-pressure fluid into the sealed space to expand the straight pipe portion, and bringing at least one of the molds closer to the other to press the expanded straight pipe portion against the flange. .

Further, when an inner cylinder is provided inside the bellows, each of the above steps is performed with the end of the inner cylinder overlapped with the inner surface of the straight pipe part of the bellows.

[Function] With the above configuration, the straight pipe portion of the bellows is once expanded by the high-pressure fluid, and after the expanded portions are overlapped by the approach of the mold, the peaks and overlapped portions of the bellows push the flange from both ends in the axial direction. It will be firmly attached.

Further, in the case of a bellows having an inner cylinder, the end of the inner cylinder is overlapped with the straight pipe part of the bellows, and the flanges are connected.

Since these overlapping portions can be formed larger than when the peaks are flattened, the bonding strength with the flange is improved.

[Example] FIG. 1 shows a forming apparatus 10 used in the method for attaching a bellows to a flange according to the present invention.

In this molding device 10, a rectangular pedestal 12 is fixed to a base 11. A hole 12a having an L-shaped cross section is bored in the pedestal 12, and this hole 12a communicates from a side entrance 12b of the pedestal 12 to an upper exit. An elongated first core bar 13 extending upward is screwed onto the exit side of the hole 12a.

As shown in FIG. 2, the interior of the core bar 13 is hollow and forms a passage 14, which communicates with the hole 12a of the pedestal 12. The outside of the core metal 13 is a cylinder 1
5, and ring-shaped presser plates 16 and 17 are fitted to the upper and lower ends of the cylinder 15, respectively. Further, the upper part of the core metal 13 has a larger diameter, and the tip thereof forms a flange 18. Seal rings 21 and 22 are fitted onto the upper part of the core metal 13 via two packings 19 and 20, and these are held between the flange 18 and the holding plate 16.

On the other hand, a nut 42 is screwed below the core bar 13, and the upper surface of the nut 42 is in contact with the presser plate 17. Therefore, when the nut 42 is rotated and tightened, the distance between the flange 18 and the presser plate 16 becomes smaller, and the seal rings 21 and 22 expand and deform slightly outward.

As can be seen from FIGS. 1 and 3, one bellows 23 is fitted into the core metal 13. The bellows 23 has straight pipe parts 23a and 23b at both ends, the seal rings 21 and 22 are in contact with the inside of the straight pipe part 23a, and the lower end of the straight pipe part 23b is supported by the holding plate 17. .

A first mold 24 is fitted above the bellows 23 from the outside as shown in FIGS. 1 and 4. The mold 24 has a pair of split mold shapes and is provided with an annular groove 25 that fits into each peak of the bellows 23, and is placed on the support base 11a.

A stepped portion 26 is formed on the upper surface of the mold 24, and the lower surface of the flange 27 fits into the stepped portion 26 when the flange 27 is inserted into the straight pipe portion 23a.

The upper end of the straight pipe portion 23a is closed by a second core bar 28, and the core bar 28 is secured to the second core bar by a bolt 29.
is connected to the mold 30. A rod 31 protrudes from the center of the lower end of the core metal 28, and its tip touches the core metal 1.
Part of the passage 14 of No. 3 is entered. Rod 31
A hole 32 communicating with the passage 14 is provided inside the rod 31, and the hole 32 is bent in the middle to communicate with the outside of the rod 31. Furthermore, a seal ring 33 and packing 34 are wound around the upper outer periphery of the core bar 28 .

On the other hand, the mold 30 is approximately disk-shaped and has a central hole 35, and a core metal 38 is accommodated in the central hole 35.
A slight gap is formed between the core bar 28 and the central hole 35, and the upper end of the straight pipe portion 23a is inserted into this gap.

Further, on the upper and lower surfaces of the mold 30, a stepped portion 36,
37 are provided. A press ram 38 is fitted into the stepped portion 36, and a spacer 38 is fitted into the stepped portion 37, as shown in FIG. The ram 38 presses the mold 30 to form the straight pipe portion 23a, and the spacer 39 maintains the mold 24 and the mold 30 at a constant distance.

Therefore, when the bolt 29 is rotated to move the core metal 28 slightly upward, the seal ring 33 is crushed and pressed against the inner surface of the straight pipe portion 23a. Therefore, a sealed space 40 is formed in the straight pipe portion 23a by the core metal 13 and the core metal 28. Also, mold 2
4, 30 and the spacer 39, the straight pipe section 23
A certain space is also formed outside of a. The molding apparatus 10 configured as described above is assembled and operated in the following order.

First, as shown in FIG.
7 and nut 22 are assembled. Next, as shown in FIG. 3, the bellows 23 is inserted into the first core metal 13 and fitted into the stepped portion 17a of the presser plate 17.

Next, as shown in FIG. 4, the bellows 23 is fixed from the outside using the first mold 24, and the flange 27 is fitted into the straight pipe portion 23a of the bellows 23.

Next, the second core metal 28 and the mold 30 are fitted to the upper end of the straight pipe portion 23a with a predetermined interval provided by a spacer 39 (FIG. 1). When the bolts 29 and nuts 42 are tightened in this state, the seal ring 3
3, 21, and 22 are deformed, and the inside of the straight pipe portion 23a is completely sealed.

Subsequently, the ram 38 is brought into pressure contact with the upper end of the mold 30 to fix the mold.

Here, when high-pressure fluid is injected from the inlet 12b of the pedestal 12 using a high-pressure generator (not shown), this fluid rises in the passage 14 as shown by the arrow in FIG. 32 and flows into the sealed space 40. Therefore, the straight pipe portion 23a starts to expand outward as shown by the arrow in FIG. At this time, since the core metal 28 and the mold 30 are pressed by the ram 38, they do not float up, and the expansion pressure of the liquid is maintained at a predetermined value during this time.

Next, when the spacer 39 is removed and the mold 30 and the core metal 28 are pressed downward by the ram 38, the expanded straight pipe portion 23a is crushed and pressed against the upper surface of the flange 27, as shown in FIG. For this reason, it is desirable to form a recess 30a on the lower surface of the mold 30 to receive the deformed straight pipe portion 23a (see FIG. 5).

The high pressure fluid is then removed, the ram 38 is retracted, and the bolt 29 and nut 42 (FIG. 1) are loosened. Subsequently, the molds 30, 24 and the core metal 28 are removed, and the bellows 23 is once removed from the core metal 13 and set in the opposite direction, that is, with the straight pipe portion 23b facing upward. later,
Repeat exactly the same operation as above.

After completing these steps, a flanged bellows 23 as shown in FIG. 6 is obtained. Finally, as shown in FIG. 7, the remaining portions of the straight pipe portions 23a and 23b are cut.

As shown in FIG.
3 and the flange 27, the above-mentioned steps are first performed with the end of the inner cylinder 41 superimposed on the inner surface of the bellows straight pipe part 23a. Finally, the straight pipe portion 23a and the inner cylinder 41 are pressed against the flange 27 in a two-layered state. The other end of the inner cylinder 41 is left unfixed so that the expansion and contraction of the bellows 23 is not hindered.

[Effects of the Invention] As explained above, the present invention includes the steps of inserting the bellows into the first core metal and fixing the bellows with the first mold, and fitting the flange to the straight pipe portion of the bellows. a step of supporting the bellows with a first mold; a step of closing the end of the bellows with a second core metal and forming a sealed space inside the straight pipe portion with the first and second core metals; a step of fixing the end of the bellows with a second mold placed at a predetermined distance from the first mold; a step of introducing high-pressure fluid into the sealed space to inflate the straight pipe portion; and a mold. Since the bellows and the flange are connected by pressing one side of the bellows and pressing the expanded straight pipe part against the flange, it is possible to form a large overlapping part, and the two can be connected without welding. This has the effect of reliably joining the parts.

In addition, in the case of bellows equipped with an inner cylinder, the end of the inner cylinder is integrally connected to the flange of the straight pipe part of the bellows, preventing leakage of internal fluid and falling of the inner cylinder in vertical piping. can do.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of a forming device used for attaching the bellows to the flange, Figs. 2 to 4 are longitudinal sectional views showing the assembled state of the bellows and flange, and Fig.
The figure is an enlarged sectional view showing the operating state of the molding device.
The figure is a longitudinal sectional view showing the bellows after molding, FIG. 7 is a longitudinal sectional view of the completed bellows, and FIG. 8 is an enlarged sectional view of the bellows having an inner cylinder. 10... Molding device, 13... First core metal, 14
...fluid passage, 23 ... bellows, 23a ... straight pipe section, 24 ... first mold, 27 ... flange,
28...Second core metal, 30...Second mold, 38
...Ram, 40...Sealed space, 41...Inner cylinder.

Claims (1)

[Claims] 1. A step of inserting a bellows having a straight pipe part into a first metal core and fixing the bellows with a first mold, and a step of fitting a flange to the straight pipe part and fixing the bellows with a first metal mold. a step of supporting the bellows with a mold; a step of closing the end of the bellows with a second core metal and forming a sealed space inside the straight pipe portion with the first and second core metal; a step of fixing the end of the bellows with a second mold placed at a predetermined distance from the mold; a step of introducing high pressure fluid into the sealed space of the straight pipe section to expand the straight pipe section; A method for attaching a bellows to a flange, the method comprising the step of bringing at least one of the molds close to the other to press the expanded straight pipe portion against the flange. 2. The method for attaching a flange to a bellows according to claim 1, wherein the first mold has a two-part shape and is fitted and fixed to the outside of the bellows. 3. The method for attaching a bellows to a flange according to claim 1, wherein the second core metal is incorporated into a second mold, and both integrally support the end of the bellows. 4. The bellows flange attachment method according to claim 1, wherein the high-pressure fluid is sent into the sealed space of the straight pipe portion through communication holes formed in the first and second core metals. 5 In a flange attachment method for a bellows having an inner cylinder provided inside the bellows and straight pipe parts at both ends, the bellows is attached to the first core metal with the end of the inner cylinder overlapped with the inner surface of the straight pipe part of the bellows. and fixing the bellows with a first mold; fitting a flange to the straight pipe part and supporting it with the first mold; and fixing the bellows with a second metal core. and a step of closing an end of the inner cylinder and forming a sealed space inside the inner cylinder with the first and second cored metals, and a second metal mold disposed at a predetermined distance from the first mold. a step of supporting the ends of the straight pipe part and the inner cylinder with a mold; a step of introducing high pressure fluid into the sealed space to expand the straight pipe part and the inner cylinder; and a step of supporting at least one of the molds with the other mold. A method for attaching a bellows to a flange, the method comprising the step of bringing the expanded portion close to the flange and pressing the expanded portion against the flange.