JPH0473489A - Tube jointing method - Google Patents

Abstract

PURPOSE:To obtain a tube jointing method allowing the uniform compression of a packing and the application of a less bolt tightening force by keeping an angle formed between a collar section and a tube body at an acute angle. CONSTITUTION:The collar sections 2 and 2 of a tube end molded through a collar bending process, is made to form an acute angle of alpha with a tube body. A plate packing 3 is provided between the collar sections 2 and 2, and flange fixtures 4 and 4 are used to clamp the collar sections 2 and 2. Before tightening bolts and nuts 5, the external surface 21 of the collar section 2 is positioned outside by an angle of hcosalpha, relative to the apex angle internal side 20 of the collar section 2 (length: h). Even if the tightening amount of each bolt 5 is more or less different, it is possible to reduce the effect of such a difference upon the compression force of the packing 3 in inverse proportion to h<3>, when the length 'h' is increased. The partial tightening of the packing 3 due to the irregular tightening of the bolts 5, therefore, can be minimized. Also, the packing 3 is compressed with local concentrated pressure at the apex angle internal side 20 of the collar section 2 and, therefore, an enough compression force can be made to act on the sealing position of the packing 3.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for joining pipes used for transferring fluids such as water and gas.

(Prior art) When joining metal pipes in a watertight or airtight manner, the ends of the metal pipes are formed into vertical flanges using a flanging device, and a flat backing is placed between the vertical flanges of the tube ends thus formed. intervene,
It is known that the vertical flanges are sandwiched between flange metal fittings, and these flange metal fittings are fastened with bolts and nuts to compress the entire surface of the flat backing between the vertical flanges. The work is simpler than the welding method in which the collar is provided by welding a fishing fitting to the end of the tube.

(Problem to be solved) In this flange joining method, as with other flange joining methods, the compressed state of the backing becomes uneven in the circumferential direction due to uneven tightening of each bolt, resulting in a predetermined sealing performance. It is often not possible to guarantee that Also, considering workability, it is desirable to keep the number of bolts relatively small (4 to 6), and since the entire surface of the backing is pressurized and compressed by tightening such a small number of bolts, - It is necessary to tighten the bolts with a large force, and uneven tightening of the bolts under such a large bolt tightening force tends to cause a significant deterioration in sealing performance.

However, in the past, it has been known to insert a spring into the bolt in order to eliminate the unrestrained tightening of the bolt, but in this case, a decrease in workability due to an increase in the number of parts is unavoidable, and the It is also disadvantageous in terms of management.

The purpose of the present invention is to compress the backing sufficiently uniformly even if the amount of tightening of each bolt is slightly uneven by simply adding a simple process to the conventional flange joining method described above. The purpose of bolt tightening is to provide a method of joining pipes that requires less force.

(Means for Solving the Problems) A method for joining pipes according to the present invention is to form the pipe ends into flanges by flange processing, and to sandwich the flanges of the pipe ends to be joined together with flange fittings. In the pipe joining method in which the fittings are fastened with a fastener to seal between the flanges, the configuration is characterized in that the angle formed between the flanges and the tube body is an acute angle.

The pipes targeted in the present invention are mainly steel pipes, aluminum pipes, and copper pipes, but the present invention can also be applied to metal-resin composite pipes lined with plastic having a relatively high elastic limit.

(Explanation of Examples) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1A and FIG. 1B are explanatory views showing one embodiment of the present invention. FIG. 1A shows the state immediately before bolt tightening, and FIG. 1B shows the state immediately after bolt tightening. are shown respectively.

In FIG. 1A and FIG. 1B, 1 and 1 are tubes to be joined to each other, 2 and 2 are flange parts formed by flange processing of the tube ends, and the angle formed by this flange part and the tube body. α is an acute angle. 3 is a plate-shaped backing interposed between the flanges 2 and 20. Reference numerals 4 and 4 indicate flange fittings that sandwich the flanges 2 and 2.

5 shows an example of a fastener, in which several bolts and nuts (4 to 6) are provided at regular intervals in the circumferential direction.

As shown in FIG. 1A above, when tightening the bolt/nut 5, since the angle α is an acute angle, the flange 2
The outer circumference 21 of the flange is hc with respect to the inner circumference 20 of the apex angle (length h)
It is located outside by osα.

By tightening the pole 1 and nut 5, both flanges 2°2
The apex inner circumferences 20 and 20 of the flange fittings 4 abut each other, and each flange 2 is attached to the flange fitting 4 at the outer circumference 21 using the butt points as fulcrums.
The flange portion 2 is bent as the bolt/nut 5 is tightened.

In this case, since the Young's modulus of the backing 3 can be ignored with respect to the Young's modulus of the flange 2, the flange 2 can be mechanically approximated by using the fulcrum 20 as a fixed fulcrum and the outer peripheral end 21 as a load application point. It can be considered as a simple cantilever beam. Therefore,
As shown in Fig. 1B, the tensile reaction force P acting on the bolt 5 when the amount of deflection of the collar 2 is δ is P=δ・3EI/h3□■ (where, E is the young (2) is the cross-sectional moment of inertia of the flange), and this P acts as a reaction force on the fulcrum 20 in terms of force balance, and this P compresses the backing 3 and performs a sealing action.

Therefore, when the tightening amount of the bolt 5 (the amount of screwing in the nut) changes by Δδ, the change ΔP in the backing compression force is ΔP=3EI/h3·Δδ ■, and the tightening of each bolt 5 Even if there is a slight difference in the amount, the effect of the difference on the compressive force of the backing 3 can be made smaller in inverse proportion to h3 by increasing h, so the tightening of the bolts 5 can be reduced due to uneven tightening of the backing 3. can sufficiently keep the non-uniformity to a slight level. In addition, since the backing 3 is compressed by localized concentrated pressure at the apex inner circumference 20 of the flange 2,
Even if all the bolts are tightened with a small force, sufficient compressive force can be applied to the sealing location due to the concentrated pressure.

In the above, when the bolt 5 is tightened until the collar 2.2 becomes vertical (in equation 0, δ=hcosα), the tightening force P of the backing 3 is P=3E I ・cosa/h2 ■ Become.

In the above, if the angle α is too small, the backing 3
Tightening will make the direction P larger than necessary. Therefore, it is desirable that α be an acute angle that is 2° to 20° smaller than 90°.

The backing 3 may be made of rubber such as butyl rubber, styrene-butadiene rubber, or nitrile rubber, or an inorganic material such as asbestos, but it is preferable to use relatively soft rubber. Steel, aluminum, copper, or the like is used for the flange fitting 4, but it is preferable to use one made of the same material as the tube in order to prevent dissimilar metal corrosion with the tube.

In the above process, in order to form a flange with an acute apex angle on the tube end by flange processing, first, as shown in FIG. 2A, the diameter of the tube end 10 is expanded into a trumpet shape, and then As shown in FIG. 2B, a method can be used in which the trumpet portion 10 is formed into an umbrella shape using a male mold 61 and a female mold 62. In this case, as shown in FIG. 3A, the tapered core 62 is pushed in to expand the diameter of the tube end in a trumpet shape, and as shown in FIG. In particular, in the case of a short tube, as shown in FIG. A pressurizing medium such as oil, water, or rubber is put in, and rams 66 and 66 are pressurized from both ends of the tube 1 to pressurize the medium 65, and the central part of the tube is shaped into a triangular groove. A method such as cutting the center of the section can be used.

FIG. 4 shows another embodiment of the present invention, in which the end of a metal-resin composite tube 1 in which a resin layer 12 is provided on the inner surface of a metal tube 11 is turned into a flange 2 with an acute apex angle 21. Form and both tubes 1
．． Butt the flanges 2, 2 of 1, sandwich these flanges 2, 2 with flange metal fittings 4, 4,
are fastened by tightening bolts and nuts 5,
Since the resin layer 12 is used as a backing material, the plate-shaped backing is omitted.

In this other embodiment, in the process of flange-backing the tube end, a resin layer is provided on the inner surface of the metal tube, and then the tube end is formed into a flange with an acute apex angle by the method described above, as shown in FIG. As shown in FIG. 5A, the metal tube end 110 is formed into a flange with an acute apex angle, and then a synthetic resin tube 12 is inserted into this metal tube 11, and this synthetic resin tube 12 is formed as shown in FIG. 5B. As shown in FIG. 6, the synthetic resin tube end 120 is heated and softened, and then expanded and bonded to the flange 110. Alternatively, as shown in FIG. A synthetic resin main pipe 121 is placed on the inner surface of the metal pipe 11 which has been subjected to turning processing, and a synthetic resin main pipe 121 is attached to the flange part 11.
0 and the tube portions 111 in the vicinity thereof, a method of gluing synthetic resin short tubes 112 that have been flanged and molded can be used.

(Effects of the Invention) The pipe joining method according to the present invention has the above-described configuration, and is different from the conventional flange joining method by simply making the angle between the flange and the pipe body acute.・As the nut is tightened, the flange is elastically deformed, and the backing between the apex angles of the flange can be compressed by the reaction force, so the flange has the same effect as a spring when tightening a bolt or nut. Even if the bolts are tightened somewhat unevenly, sealing performance can be guaranteed, and the effort required is about the same as before. In addition, since the backing is locally concentratedly pressurized between the apex angles of the flange, even if all the bolts are tightened with a small force, the backing can be pressurized with sufficient contact pressure due to the concentrated effect, and the backing can be pressurized with sufficient contact pressure. -The tightening force can be reduced.

[Brief explanation of the drawing]

1A and 1B are explanatory diagrams showing one embodiment of the present invention, and FIG. 1A shows the previous state of bolt tightening, and FIG.
Figure B shows the state after bolt tightening, Figures 2A and 2B are explanatory diagrams showing an example of the tsuba-gaeshi processing method used in the present invention, and Figure 2A is an intermediate stage. 2B shows the state at the end of machining, FIGS. 3A, 3B, and 3C are explanatory diagrams showing the tools used for the above-mentioned trumpet-shaped machining, and FIG. FIG. 5A and FIG. 5B are explanatory diagrams showing another embodiment of the present invention, and FIG. 5A is an explanatory diagram showing an example of the tsuba-gaeshi processing method used in the above-mentioned another embodiment, and FIG. 5A is an intermediate stage state. 5B shows the state at the end of machining, and FIG. 6 is an explanatory diagram showing the separate bristle-back machining method used in the above-mentioned other embodiment. 1... Pipe, 2... Flange, α... Angle between the collar and the tube body, 4... Flange fitting, 5... Bolt/Nand. Patent applicant: Sekisui Chemical Co., Ltd. Representative Hiroshi 1) Kaoru Figure 1A Figure 1B Figure 3C Figure 4Figure 5A Figure 5B Go to Figure 2Figure 2B Figure 3A Figure 3B Figure 6

Claims (1)

[Claims] A pipe in which the pipe ends are formed into flanges by flange processing, the flanges of the tube ends to be joined to each other are sandwiched between flanges, and these flanges are fastened with a fastener to seal between the flanges. A method for joining tubes, characterized in that the angle formed between the collar portion and the tube body is an acute angle.