WO2010131347A1

WO2010131347A1 - Pipe joint structure

Info

Publication number: WO2010131347A1
Application number: PCT/JP2009/058971
Authority: WO
Inventors: 一三小林
Original assignee: Kobayashi Kazumi
Priority date: 2009-05-14
Filing date: 2009-05-14
Publication date: 2010-11-18

Abstract

A joint structure which stably achieves high connection strength in bonding of metal pipes by an adhesive agent. Circular conical-shaped and funnel-shaped tapered surfaces (3a, 4a) are respectively formed at ends of metal pipes (3, 4), and the tapered surface (3a) is coaxially fitted in the tapered surface (4a). The tilt angle ? of the tapered surfaces (3a, 4a) is set within the range from three to eight degrees. A projection (21a) projects from the tapered surface (3a). The distance between the tapered surfaces (3a, 4a) is set within the range from 0.05 mm to 0.3 mm, and an adhesive agent (6) is placed in the gap between the tapered surfaces.

Description

[Name of invention determined by ISA based on Rule 37.2] Pipe connection structure

The present invention relates to a pipe connection structure in which a plurality of pipes are connected by an adhesive, and a pipe connection method implemented in the connection structure.

For connection of metal pipes, fusion welding, liquid phase diffusion connection, etc., or connection using a flange are known.

Patent Document 1 discloses a scarf connection related to the connection of dissimilar metals. The scarf connection is a connection method in which the free edge stress specificity is lost and the connection area is expanded. The scarf connection in Patent Document 1 is intended for brazing, diffusion bonding, and welding plates. Patent Document 2 discloses a technique for connecting a steel pipe having a groove formed by an inclined surface using a liquid phase diffusion connection. An inclined surface is formed on each of the steel pipes to be connected. An alloy having an eutectic composition with a low melting point is interposed between them, and the alloy is melted by pressing and heating.

Non-Patent Document 1 describes a spliced pipe-type connection of a metal pipe using an adhesive, and when using a straight-side tubular connection, a clearance from the fitting pipe into which the adhesive is poured is set to 0. 0. It is described that the range of 13 mm to 0.15 mm is effective.

JP 2004-255388 A JP-A-9-317959

The present inventor disclosed a connection structure of a metal tube by an adhesive as PCT / JP2008 / 071489 (Japanese Patent Application No. 2007-337449). This shows a technique of connecting a metal tube with an adhesive by extrapolating a tapered sleeve to the metal tube. Here, since the gap distance between the metal tube filled with the adhesive and the sleeve affects the bonding strength, it is necessary to preliminarily process the outer shape of the metal tube in order to control this. have. This is due to the fact that the diameter tolerance of the JIS standard is larger than the control value of the distance between the gaps.

The inventor cuts the end face of the metal tube into a taper shape, which is easier than the perfect circle processing. Therefore, paying attention to the structure when the cross-sectional shape is a scarf shape, the connection technique using an adhesive is used. investigated. An adhesive made of a resin cannot change the composition of the connection interface, and is a connection technique that involves a change in the metal-side interface using liquid phase diffusion or the like according to Patent Document 1 or welding. Non-Patent Document 1 shows the concept of jointed pipe connection of metal pipes using an adhesive. However, if stress concentration occurs at the connection interface, the adhesive force of the adhesive cannot be exhibited. On the other hand, in order to develop the adhesive strength by the adhesive, the film thickness is as thin as possible, and it is preferable to apply it uniformly to the adhesive surface in the range of 0.05 mm to 0.3 mm, for example. However, it is difficult to always realize such a film thickness stably in the field work. The present inventor examined a shape in which stress is uniformly dispersed when connecting with an adhesive, and a structure capable of stably connecting a joint using a scarf shape.

In order to achieve the above object, one tube having a conical tapered surface whose end portion is reduced in diameter toward the front side and the other tube having a funnel-shaped tapered surface whose end portion is reduced in diameter toward the back side The tapered surfaces are connected to each other by an adhesive, the inclined angles of the tapered surfaces are equal and within a range of 3 to 8 degrees, and are on the tapered surface and within the pipe. From an outer periphery of a tube having an inner peripheral side projecting portion protruding concentrically on the circumferential side in a ring shape in a height range of 0.05 mm to 0.3 mm and coming into contact with a taper surface facing the opposite surface, and the funnel-shaped taper surface An adhesive press-fitting hole penetrating the tapered surface is provided.

According to the present invention, when the taper surface is bonded by an adhesive, the shape of the tube is uniformly distributed at the taper surface interface, and the adhesive strength per unit area of the adhesive is used to determine the shape of the tube. A connection technique capable of providing connection strength can be provided. In addition, it is possible to provide a structure that can stably perform this connection on the piping site. According to the present invention, when an excessive tensile force is applied in the direction of the center line of the tube, the adhesive connection is such that the non-influential base material location of the tube is cut before the connection location by the adhesive. Is also possible.

It is a figure which shows the edge part shape of the

metal pipes

1 and 2. FIG. It is a figure which shows the adhesion condition of an adhesive agent. It is sectional drawing which shows the connection structure of the metal pipes 3 and 4. FIG. It is a figure which shows the example of a connection using the

sleeves

7 and 9 which consist of a short tube. It is a figure which shows the other connection structure of a metal pipe. 5 is a cross-sectional view showing a connection structure using a joint pipe 13. FIG. It is sectional drawing which showed the connection structure using other joint pipes. It is sectional drawing which shows the connection structure of the joint 20 provided with the metal pipe 3 and the flange part 20a. It is sectional drawing which showed the connection structure using the

joint pipes

23 and 35. FIG. It is sectional drawing which showed the connection structure using the joint pipes 37 and 39. FIG. 5 is a cross-sectional view showing an example in which a ring groove 4b is provided on the inner peripheral side of the tapered surface 4a of the metal tube 4. It is a figure which shows the connection structure of the

joints

41 and 42 provided with the metal pipe 1 and the flange part 41d. 3 is a cross-sectional view showing a connection structure using a joint pipe 50. FIG. It is sectional drawing which showed the connection structure using the joint pipe | tube 51. FIG. 5 is a cross-sectional view showing a connection structure using a joint pipe 52. FIG.

1, 2, 3, 4, 11, 12, 16, 17

Metal pipe

6, 8 Adhesive 7, 9

Sleeve

13, 14, 50, 51, 52

Joint pipe

20, 41, 42 Joint 21 Embankment 21a, 21b Projection Part

When the end surfaces are bonded to each other with an adhesive and peeled off from the left and right, the stress tends to concentrate on the free end having a large shape change.

Fig. 1 shows the end shapes of the

metal tubes

1 and 2 used for the verification. The same material is used for these

metal tubes

1 and 2. The end of the metal tube 1 has a conical tapered surface 1a concentric with the center line c of the metal tube 1 and reduced in diameter toward the end toward the end cut off perpendicular to the center line c. Is formed. Further, at the end portion of the metal tube 2, a funnel whose diameter is reduced toward the inner side at the inner peripheral surface of the end portion that is concentric with the center line c of the metal tube 1 and cut off perpendicularly to the center line c. A tapered surface 2a is formed. The inclination angles of the taper surface 1a and the taper surface 2a are the same angle θ in relation to the center line c.

The adhesive is applied to the taper surface 1a (or the taper surface 2a), and the metal tube 1 and the metal tube 2 are arranged in a single line in parallel and connected with the center line c aligned. The distance between the taper surface 1a and the taper surface 2a is maintained at a size within a range of 0.05 mm to 0.3 mm on all the opposing surfaces of the taper surface 1a and the taper surface 2a to cure the adhesive.

As the

metal pipes

1 and 2, those having higher hardness than the steel pipes of STPT410Sch160 and 20A that are actually used are used so that the steel pipe portion in the adhesive connection range does not break even in the tensile strength (load) test. . The gap is 0.15 mm. As the adhesive, an epoxy structural adhesive (for example, a product “Scotch-WeldXA7416” manufactured by Sumitomo 3M) was used. The taper angle was 5 degrees. After the adhesive was cured, a tensile strength (load) test was performed. As a result, the connection portion was broken at 141 KN. This is a value larger than the minimum value 92KN of the yield strength (load) of the steel pipes of STPT410Sch160, 20A. FIG. 2A shows the broken adhesive surface. The adhesive itself was not broken, and peeling of the adhesive from the bonding interface was observed, but the peeling position was irregular on the bonding surface, and the breakage proceeded particularly at the boundary position of the inner and outer circumferences of the tapered surface. The situation was not seen. The minimum value of the tensile strength (load) of STPT410Sch160, 20A standard is 154KN.

According to the above verification, by forming and adhering the taper surface, the stress distribution can be treated equally in any place of the taper surface 1a and the taper surface 2a.

The fact that the stress can be equalized means that the strength at which the

metal tubes

1 and 2 are connected can be predicted based on the adhesive strength per unit adhesive area of the adhesive.

FIG. 2B is a diagram showing the results of measuring the breaking strength (load) when the size and taper angle of the metal tube are changed. The horizontal axis shows the standardized strength in terms of adhesion area, breaking strength (load), and adhesion area of 3000 mm ² . The reason for changing the size of the metal tube is to confirm whether the relationship between the bonding area and the strength (load) is proportional. When the size of the metal tube was 20A, 25A, and 32A, it was observed that the adhesive strength per unit area would be the same if the taper angle was the same. Therefore, if the taper angle is the same, it can be said that the strength is proportional to the adhesion area. On the other hand, when the taper angle is changed to 8 degrees and 5 degrees, when the adhesive area is converted to 3000 mm ² , in the case of 20A, it is 145 KN at 8 degrees and 134 KN at 5 degrees, and the unit area is larger when the taper angle is increased. The hit strength tends to increase. This shows the same tendency at 25A and 32A. From this result, when it has a taper angle of 8 degrees or more, it is inferred that there is an angle that can treat the stress distribution as uniform up to a certain range. However, increasing the taper angle results in a decrease in the bonding area, so that the strength required for the metal pipe connection cannot be obtained and cannot be put to practical use.

On the other hand, the adhesive strength τ per unit area of the adhesive is derived from the following equation (1) when the area of the tapered surface 1a (or the tapered surface 2a) is S.

The adhesive strength K obtained by this equation is the connection strength of the metal tube when the stress distribution rate with respect to the tensile force applied to the metal tube is equal to the area S.

By setting the adhesive strength K to be larger than the breaking strength (load) of the

metal tubes

1 and 2 themselves, it is possible to obtain a connection in which the metal tube side breaks rather than the bonded portion with respect to the tensile load.

The thickness of the metal tube varies depending on the diameter of the tube (10A, 125A, 500A, 1000A, etc.), but by setting the inclination angle θ within 8 degrees, the connection strength is higher than the yield point or fracture strength of the metal tube itself. A sufficient area S can be set to be large.

FIG. 2C shows the relationship between the adhesive layer thickness t and the adhesive strength τ of the adhesive 4. The horizontal axis indicates the adhesive layer thickness t, and the vertical axis indicates the breaking strength (load) of the adhesive. As understood from FIG. 2C, the breaking strength (load) decreases in the range where the layer thickness t of the adhesive is larger than 0.3 mm. Therefore, the distance between the taper surface 1a and the taper surface 2a is preferably kept so that the adhesive layer thickness t is 0.3 mm or less.

Hereinafter, the shape of the tapered surface that stably realizes a desired adhesive film thickness in the installation work in the field will be described.

A procedure for forming a connection structure of two metal pipes having the same diameter using carbon steel, stainless steel or duralumin as a base material will be described.

In FIG. 3, a conical tapered surface 3a is formed on a metal tube 3 of STPT410Sch160, 20A, and a funnel-shaped tapered surface 4a is formed on a metal tube 4 of STPT410Sch160, 20A by a lathe. The inclination angle θ of the

tapered surfaces

3a and 4a is the same as that in the previous embodiment. The tapered surface 3a of the metal tube 3 has a bank portion 21 that rises in a ring shape from the tapered surface 3a. The bank portion 21 has a ring-shaped protrusion 21a on the inner peripheral side and a protrusion 21b on the outer peripheral side from the inner and outer peripheral positions of the tapered surface 3a. The

protrusions

21a and 21b have a height d in the range of 0.05 mm to 0.3 mm from the tapered surface 3a. The

protrusions

21 a and 21 b are portions left uncut when the tapered surface 3 a is ground on the metal tube 3. When this abuts on the tapered surface 4a, the inter-surface distance between the

tapered surfaces

3a and 4a is maintained within a range of 0.05 mm to 0.3 mm. On the metal tube 4 side, a through hole e is formed from the outer peripheral surface to the tapered surface 4a in the thick portion where the funnel-shaped tapered surface 4a is formed. A female screw is formed on the inner peripheral surface side of the through hole e. A plurality of through holes e may be formed at equal angular intervals in the metal tube 4 having the tapered surface 4a as shown in FIG. 3A.

As shown in FIG. 3B, the center lines c are aligned, and the respective metal tubes 3 and 4 are supported by a support tool. Thereafter, either or both of the metal tubes 3 and 4 are moved on the center line c, and the tapered surface 3a and the tapered surface 4a are brought into contact with each other (FIG. 3C).
Next, the metal tube 3 and the metal tube 4 are pressed with the pressure F1. Under this state, the adhesive 6 is press-fitted into the through hole e with a pressure F2 that is smaller per unit area than the pressure F1. The reason why the pressure is smaller than the pressure F1 is to prevent the adhesive from getting over the protrusion 21a and leaking inside the metal tubes 3 and 4. If it leaks into the metal tubes 3 and 4, the adhesive 6 hardens in a raised state, peels off as a foreign substance, and may be mixed into the fluid flowing in the tube. This can be avoided by the protrusion 21a. Moreover, the adhesive agent 6 will be in the state from which the outer peripheral side protrusion 21b was completely interrupted | blocked directly from the external rain water and sunlight. The screw 5 seals the through hole e, and is inserted into the through hole e so that the adhesive 6 is not exposed to the atmosphere.

Thereafter, a heating tool such as a heating mat is wound around the tapered surface 3a, the adhesive 6 and the tapered surface 4a, and the adhesive 6 is heated to about 140 ° C. and held and cured. In this example, the thermosetting adhesive 6 is used, but a room temperature curing adhesive may be used depending on the environment of the piping site.

When a tensile strength (load) test was performed on the metal tube connection structure thus produced, the adhesive interface was broken at 116 KN. The metal tube used in the test has the same shape as STPT410Sch160, 20A and has a higher tensile strength (load). Compared with the connection structure of FIG. 1, there is a difference of 29KN (141KN-116KN). In the case of the connection structure of FIG. This is due to the decrease. The adhesive area in the connection structure of FIG. 1 is a 3116Mm ^2, a in FIG. 3 2770mm ^2. When the strength is compared in terms of an adhesion area of 3000 mm ² , the connection structure in FIG. 1 is 134 KN. Compared with the converted value 126KN of the connection structure of FIG. 3, it is reduced by 8KN. This decrease is considered to be a decrease in strength due to the loss of uniformity of the tapered surface. Note that 116KN where the adhesive interface is broken exceeds the minimum value of the yield strength (load) of STPT410Sch160, 20A.

FIG. 4 shows an example of connection using a straight sleeve 7 made of a short pipe in addition to the connection structure of FIG. In this embodiment, the screw 5 is not used. In FIG. 4A, the sleeve 7 is externally fitted in a state of straddling the outer peripheral surface of the metal tube 3 and the outer peripheral surface of the metal tube 4 by a distance equal to both sides from the connection portion on the outer periphery of the metal tube. The length of the sleeve 7 is a length obtained by securing the length of the sleeve on both sides around the dividing point Z on the outer periphery of the metal tubes 3 and 4 and further extending by 10 mm. The length may be the same on both sides around the dividing point Z. Further, the length of the sleeve may be secured and further extended. The sleeve 7 covers the adhesive 6 sandwiched between the tapered surface 3a and the tapered surface 4a so as not to be exposed to the atmosphere side.

The adhesive 8 is filled between the inner peripheral surface of the sleeve 7 and the outer peripheral surfaces of the metal tubes 3 and 4. The adhesive 8 may be the same as the adhesive 6 or may be another type. The sleeve 7 is provided with a through hole f into which the adhesive 8 is press-fitted. After the sleeve 7 is fitted on the metal tubes 3 and 4, the adhesive 8 is press-fitted through the through-hole f. The position of the through hole f is the central portion of the sleeve 7.

In the connection structure of this embodiment, the adhesive 6 filled in the interval between the tapered surface 3a and the tapered surface 4a is not directly exposed to rainwater or ultraviolet rays of sunlight due to the presence of the sleeve 7 and the adhesive 8. For this reason, the adhesive agent 6 which is resin becomes difficult to deteriorate and maintains its adhesive function over a long period of time. Further, the inner peripheral surface of the sleeve 7 and the outer peripheral surfaces of the metal tubes 3 and 4 are connected by the adhesive 8, and the connection force of the metal tubes 3 and 4 is increased.

When the tensile strength (load) test was performed on the metal tube connection structure thus prepared in the same manner as described above, the adhesive interface was broken at 194 KN. This exceeds the minimum value of the tensile strength (breaking load) which is the standard of STPT410Sch160, 20A.

FIG. 4B is an example of the sleeve 9 obtained by deforming the sleeve 7. The sleeve 9 has a cylindrical shape similar to the sleeve 7, but the outer peripheral surface of the sleeve 9 is a tapered surface that gradually increases in diameter from each end toward the center. The other points are the same as the case of the straight sleeve 7 shown in FIG. 4A.

In the connection structure of this modified example, since the outer peripheral surface of the sleeve 7 is a tapered surface continuous from the outer peripheral surfaces of the metal tubes 3 and 4, discontinuity in the shape change of the outer peripheral surface of the entire connection structure is alleviated, and the connection Stress concentration is improved when an external force in the direction of the center line is applied to the structure. When the tensile strength (load) test was performed on the metal tube connection structure thus produced in the same manner as described above, the adhesive interface was broken at 197 KN. The

sleeves

7 and 9 are made of the same material as the metal tubes 3 and 4.

FIG. 5 is a cross-sectional view of another connection structure example in which the bank portion 21 is deformed. In FIG. 5A, the bank portion 21 of the present embodiment has

protrusions

21a and 21b in linear contact with the tapered surface 4a at the inner peripheral side position and the outer peripheral side position of the tapered surface 3a of the metal tube 3. . The other points are the same as those of the connection structure shown in FIG. 3, and in FIG. 5A, the same parts as those already described are denoted by the same reference numerals.

FIG. 5B shows a surface 21c where the protrusion 21a of the bank portion 21 abuts against the tapered surface 4a. Compared with the case where the

protrusions

21a and 21b are linearly contacted as shown in FIG. 5A, the effect of suppressing leakage of the adhesive into the metal tube can be expected.

The

protrusions

21a and 21b shown in FIGS. 5A and 5B are provided on the tapered surface of the metal tube on either side. However, the protrusion 21a on the inner peripheral side protrudes from the tapered surface 4a of the metal tube 4. Also good. (For example, FIG. 5C). Similarly, the protruding portion 21 a at the outer peripheral side position may protrude from the tapered surface 4 a of the metal tube 4. Moreover, it is good also as a protrusion which protrudes from the metal pipes 3 and 4 from the both sides of the taper surfaces 3a and 4a, and is mutually abutted (for example, FIG. 5D). However, from the viewpoint of ease of processing, it is better to provide the

protrusions

21a and 21b on the conical tapered surface 3a side. In any case, the range of the

tapered surfaces

3a and 4a separated by the protrusions is 0.05 to 0.3 mm, which is fine. Further, since the adhesive 6 hardened in the gap between the

tapered surfaces

3a and 4a is exposed to the outside at the outer peripheral portion of the metal tube, it may be hidden by attaching the

sleeve

7 or 9 shown in FIG.

FIG. 6 is a cross-sectional view showing an embodiment of another metal pipe connection structure.

Tapered surfaces

11a and 12a and

protrusions

21a and 21b similar to the taper 3a of the previous embodiment are formed at the ends of the same-

diameter metal tubes

11 and 12 of the present embodiment. A joint pipe 13 made of the same material as the

metal pipes

11 and 12 is fitted over the

tapered surfaces

11a and 12a of the

metal pipes

11 and 12. The joint pipe 13 has a tapered surface whose outer

peripheral surfaces

13a and 13c gradually increase in diameter from both ends toward the center. Similarly, the inner

peripheral surfaces

13b and 13d are tapered surfaces whose diameter gradually decreases toward the center. Moreover, the through-hole g which presses in an adhesive agent is provided so that it may each penetrate from the outer

peripheral surfaces

13a and 13c to the inner

peripheral surfaces

13b and 13d.

FIG. 7 is a view showing another joint pipe 14 having a structure replacing the protrusion 21a. The joint tube 14 has the same shape as the joint tube 13 on the outer peripheral side, but is provided with a sealing annular protrusion 14e on the inner peripheral side. The sealing annular protrusion 14e is formed in a cylindrical shape on the inner peripheral side of the central position of the joint pipe 14 in the length direction. The sealing annular protrusion 14e exists between the

tapered surfaces

14b and 14d formed at both ends of the joint pipe 14, and extends from the tapered

surfaces

14b and 14d perpendicularly to the center line c, thereby forming the

tapered surfaces

14b and 14b. An outer surface is formed by annular end surfaces 14f and 14g having an angle larger than the angle 14d and an inner peripheral surface 14h having the same inner peripheral diameter as that of the

metal tubes

16 and 17. A ring groove 14i into which the O-ring 18 is fitted is formed concentrically at a position near the center of the width of each

annular end face

14f, 14g.

On the other hand, the

metal tubes

16 and 17 having the same diameter have annular end surfaces 16b and 17b formed at the tips of the

tapered surfaces

16a and 17a, respectively, and face each other in parallel with the annular end surfaces 14f and 14g of the joint tube 14. The annular end surfaces 14f and 14g are longer in the diameter direction of the center line c than the annular end surfaces 16b and 17b. The O-ring 18 fitted in the ring grooves 14i of the annular end faces 14f, 14g is sealed from the internal space of the

metal tubes

16, 17 in a liquid-tight manner. The other configuration is the same as that of the connection structure shown in FIG. 6, and the formation of the connection structure of this modification may be performed in accordance with the above description. The

joint pipes

13 and 14 are made of the same material as the

metal pipes

11, 12, 16 and 17 to be connected. In FIG. 7, substantially the same parts as those already described are denoted by the same reference numerals. The sealing annular protrusion 14e of the joint pipe 14 corresponds to a structure in which the protrusion 21a protrudes from the funnel-shaped tapered surface 4a of the metal pipe 4 shown in FIG. 5C, while the annular end faces 16b and 17b are formed. 5C corresponds to the structure in which the tapered surface on the inner peripheral side of the tapered surface 3a of the metal tube 3 is omitted, and it can be interpreted that the metal tube 4 is shortened to have the same shape at both end portions. The difference is that in FIG. 5C, the protrusion 21a of the metal tube 4 controls the thickness of the adhesive 6 by the height at which it abuts against the tapered surface 3a of the metal tube 3, whereas FIG. In this example, the thickness of the adhesive 6 is controlled by the difference in contact length between the annular end surfaces 16b and 17b of the tapered surface 3a and the annular end surfaces 14f and 14g of the sealing annular protrusion 14e. . The sealing annular protrusion 14e protrudes from the funnel-shaped tapered surface and is not easy to manufacture on the piping construction site, but can be easily manufactured as a connection part in the factory.

FIG. 8 is a cross-sectional view showing a connection structure by a joint 20 including a metal tube portion 20c and a flange portion 20a having a large outer diameter of the metal tube portion 20c.

It can be interpreted that the metal pipe portion 20c of the joint 20 is obtained by shortening the metal pipe 4 of the previous embodiment and providing a flange portion 20a at the end opposite to the end to be bonded. Bolt holes 20b are provided at equiangular intervals in the flange 20a.

FIG. 9 is a cross-sectional view showing an embodiment of another metal pipe connection structure using the joint pipe 23. In FIG. 9A, taper surfaces 31a and 32a similar to the taper 3a of the previous embodiment are formed at the ends of the same-

diameter metal tubes

31 and 32 of the present embodiment. The

metal tubes

31 and 32 are further connected to the

surfaces

31b and 32b perpendicular to the center line C at the tips of the

tapered surfaces

31a and 32a, respectively. 31b and 32b contact each other. The joint pipe 23 made of the same material as the

metal pipes

31 and 32 is fitted over the

tapered surfaces

31a and 32a of the

metal pipes

31 and 32. The joint pipe 23 has tapered surfaces whose inner

peripheral surfaces

23b and 23d gradually decrease in diameter toward the center, and the outer peripheral surface 23e is flush with the outer peripheral surfaces of the

metal tubes

31 and 32. Is formed. On the inner

peripheral surfaces

23b and 23d, ring-shaped

protrusions

23a and 23c are provided on the outer peripheral side, respectively. On the other hand, a ring-shaped leg portion 23f is provided at the center where the inner

peripheral surfaces

23b and 23d intersect. Moreover, the through-hole g which presses in an adhesive agent is each provided so that it may penetrate from the outer peripheral surface 23e to the inner

peripheral surfaces

23b and 23d. The adhesive is filled in the secured space by the

protrusions

23a and 23c and the leg 23d.

The

metal pipes

31 and 32 are quenched in the range where the

tapered surfaces

31a and 32a exist. It was confirmed that when a tensile load was applied in a state where no quenching was performed, the

metal pipes

31 and 32 that were bonded and connected had a phenomenon that the diameter contracted at the bonded site. When the diameter is reduced, the shape of the

tapered surfaces

31a and 32a is changed, and the adhesive structure cannot be maintained, and the adhesive connection portion is broken. By quenching in the range where the

tapered surfaces

31a and 32a of the

metal tubes

31 and 32 are present, the adhesion structure is maintained, and the adhesion strength expressed by the equation (1) is maintained.

FIG. 9B shows an embodiment of a connection structure using the joint pipe 35. The difference from the joint tube 23 is that ring-shaped

protrusions

23a and 23c are not provided on the inner

peripheral surfaces

35b and 35d, which are tapered surfaces whose diameter gradually decreases toward the center portion, unlike the joint tube 23. The other structures are the same.

FIG. 9C is an example in which a straight sleeve 7 is further applied to the connection structure shown in FIG. 9A. By forming the outer peripheral surface to be flush with the outer peripheral surfaces of the

metal tubes

31 and 32, such as the

joint tubes

23 and 35, the sleeve 7 as in this example or the sleeve tube 9 shown above is used. can do.

Note that the tips of the

tapered surfaces

31a and 32a of the

metal tubes

31 and 32 have

surfaces

31b and 32b perpendicular to the center line C, respectively. Since the shape change from 32a to the

surfaces

31b and 32b is large, the stress concentrates and triggers the fracture. Therefore, it is preferable that this surface is not bonded or has a weak adhesive force even when bonded. In such a state, for example, a surface treatment that makes it difficult to adhere is performed.

The angle of the tapered surface of each joint tube and the center line C of the tapered surface of each metal tube is the same.

FIG. 10 is a cross-sectional view showing an example of another connection structure of the

metal pipes

31 and 32 using the joint pipe 37. 10A, a sealing annular protrusion 37e such as the sealing annular protrusion 14e of the joint pipe 14 of FIG. 7 is provided on the inner peripheral side of the joint pipe 37. In FIG. The sealing annular protrusion 37e is formed in a cylindrical shape on the inner peripheral side of the central position of the joint pipe 37 in the length direction. The sealing annular protrusion 37e is present between the

tapered surfaces

37b and 37d formed so that the diameter gradually decreases toward the center at both ends of the joint pipe 37, and from the tapered

surfaces

37b and 37d. An outer surface is formed by annular end surfaces 37f and 37g extending perpendicularly to the center line c, and an inner peripheral surface 37h having the same inner peripheral diameter as that of the

metal tubes

31 and 32. A ring groove 37i into which the O-ring 38 is fitted is formed concentrically at a position near the center of the width of each

annular end face

37f, 37g. The joint pipe 37 is made of the same material as the

metal pipes

31 and 32.

When the

metal tubes

31 and 32 are brought together, the

surfaces

31b and 32b come into contact with the annular end surfaces 37f and 37g, respectively. The outer peripheral surface 37j of the joint tube 37 is formed on a surface that is flush with the outer peripheral surfaces of the

metal tubes

31 and 32. On the inner

peripheral surfaces

37b and 37d of the joint pipe 37, ring-shaped

protrusions

37a and 37c are provided on the outer peripheral side, respectively. Moreover, the through-hole g which presses in an adhesive agent is each provided so that it may penetrate from the outer peripheral surface 37j to the inner

peripheral surfaces

37b and 37d. The adhesive is filled in the secured space by the

protrusions

37a and 37c and the sealing annular protrusion 37e.

FIG. 10B shows an embodiment of a connection structure using the joint pipe 39. The difference from the joint pipe 37 is that ring-shaped

protrusions

37a and 37c are not provided on the inner

peripheral surfaces

39b and 39d, which are tapered surfaces whose diameter gradually decreases toward the center, unlike the joint pipe 37. The structure is the same including other materials.

FIG. 10C is an example in which a straight sleeve 7 is further applied to the connection structure shown in FIG. 10A. By forming the outer peripheral surface to be flush with the outer peripheral surfaces of the

metal tubes

31 and 32, such as the joint tubes 37 and 39, the sleeve 7 as in this example or the sleeve tube 9 of FIG. 4B is used. be able to.

FIG. 11 shows an example in which a ring groove 4b is provided on the inner peripheral side of the tapered surface 4a of the metal tube 4 of FIG. Other configurations are the same. In FIG. 11A, when attaching the metal tubes 3 and 4, the O-ring 40 is inserted into the ring groove 4b. The ring groove 4b may be provided on the metal tube 3 side, but requires a precision in processing because it is a thin portion. The ring groove 4b may also be provided on the outer peripheral side (the side indicated by 4c in the figure) of the metal tube 4 (or 3). When provided in the metal tube 3, it is within the range of the protrusion 21b.

In the example shown in FIG. 11B, the protrusion 21b on the metal tube 3 side in FIG. 3 is scraped off. With such a structure, the adhesive to be filled overflows on the outer peripheral side of the metal tubes 3 and 4.

FIG. 11C is an example in which one or a plurality of grooves h are provided from the tapered surface 3a to the outer peripheral side of the metal tube 3 with respect to the protrusion 21b on the metal tube 3 side. The grooves h are provided in a radial shape, and the protrusions 21b have the grooves h, so that the gap between the

tapered surfaces

3a and 4a is maintained more accurately than that of FIG. It is possible to vent air when filling from e and to overflow excess adhesive from the groove h. In this case, the O-ring may or may not be used on the inner week side. Also, one or a plurality of grooves that reach the outer peripheral surface from the tapered surface 3a side are provided by digging the surface of the tapered surface 4a that is in contact with the protruding portion 21b instead of the protruding portion 21b radially toward the outer periphery. May be.

In the above embodiment, the

metal tubes

3, 4, 11, 12, 16, 17 and the joint 20 or the

joints

41 and 42 to be described below may be subjected to quenching similarly to the

metal tubes

31 and 32.

FIG. 12 shows an example of

joints

41 and 42 obtained by changing the embodiment of the joint 20 having the metal pipe part and the flange part shown in FIG. The joint 41 has a groove 41c that accommodates the O-ring 43 with respect to the surfaces that face each other and connect, whereas the joint 42 is different only in that it does not have this. The structure of is the same. Therefore, only the joint 41 will be described.

The joint 41 is used to connect the metal tube 1 of FIG. 1 having no protrusion on the tapered surface. The joint 41 has a flange portion 41d in which through holes 41g used for using bolts 44 and nuts 45 are provided at equal angular intervals. FIG. 12A shows a side cross-section, and FIG. 12B shows the joint 41 as viewed from the X direction. At the end where the joint 41 is connected to the metal tube 1, one or a plurality of grooves h extending from the funnel-shaped tapered surface 41 e to the outer peripheral side of the joint 41 are provided with respect to the protrusion 41 b on the outer peripheral side. The grooves h are provided in a radial shape, and the protrusions 41b have the grooves h, so that the gap between the tapered surface 41e and the tapered surface 1a of the metal tube 1 is maintained with high accuracy, and the adhesive 6 is penetrated. When the air is filled from the hole e, air can be removed, and excess adhesive can overflow from the groove h. The protrusion 41a on the inner peripheral side is provided with a groove 41f into which the O-ring 46 is inserted.

In the connection structure on the left side of FIG. 12, the straight sleeve 7 (or sleeve 9) composed of the short pipe shown in FIG. 4 is fitted over the outer peripheral surface of the joint 42 and the outer peripheral surface of the metal tube 1. In addition, a state where the adhesive 8 is adhered is shown. The sleeve 7 (or the sleeve 9) may be used for connection between the joint 42 and the metal tube 1.

In the embodiment of FIG. 12, the groove 41 is provided in the protrusion 41b. However, the surface of the taper surface 1a that contacts the protrusion 41b on the metal tube 1 side is digged radially toward the outer periphery, thereby forming the taper surface 1a. One or a plurality of grooves that reach the outer peripheral surface from the side may be provided.

FIG. 13 shows another embodiment of the joint pipe of FIG. In the joint pipe 14 of FIG. 7, the

tapered surfaces

14b and 14d formed at both ends do not have protrusions, but in the joint pipe 50 of the present embodiment, the tapered surfaces of the

metal pipes

16 and 17 on the outer peripheral side. And a protrusion 50a that comes into contact with. As for the other configuration, the sealing annular protrusion 50e on the inner peripheral side is between the

tapered surfaces

50b and 50d formed at both ends of the joint pipe 50 in the same manner as the sealing annular protrusion 14e of the joint pipe 14. The annular end surfaces 50f and 50g that extend perpendicularly to the center line c from the tapered

surfaces

50b and 50d and have an angle larger than the angle of the tapered

surfaces

50b and 50d, and the inner peripheral diameters of the

metal tubes

16 and 17 The outer surface is formed by the same inner peripheral surface 50h. A ring groove 50i into which the O-ring 18 is fitted is formed concentrically at a position near the center of the width of each

annular end face

50f, 50g. In addition, the protrusion 50a is provided with one or a plurality of grooves in a radial pattern from the funnel-shaped

tapered surfaces

50b and 50d to the outer peripheral side of the joint pipe 50 in the same manner as in the embodiment of FIG.

FIG. 14 shows another joint pipe 51. The difference from the joint pipe 50 in FIG. 13 is that the outer peripheral surface has tapered

surfaces

51 j and 51 k that increase the pipe diameter toward the center of the joint pipe 51. Other configurations are the same as those of the joint pipe 50 of FIG.

FIG. 15 shows still another joint pipe 52. The difference from the joint pipe 50 in FIG. 13 is that the joint pipe 52 does not have the inner circumferential annular protrusion 50e seen in the joint pipe 50.

Tapered surfaces

52b and 52d formed at both ends of the joint pipe 52 reach the inner periphery. A ring groove 52i is provided concentrically at a position on the inner peripheral side, and the O-ring 18 is fitted therein. On the other hand, the metal pipe to be connected is the metal pipe 3 having the protrusion 21a only on the inner peripheral side as shown in FIG. 11, and the O-ring 18 is sandwiched between the protrusion 21a and the through hole g. Prevents the adhesive press-fitted from leaking into the metal tube 3.

13 and 15 can be used, the

sleeves

8 and 9 shown in FIG. 4 can be used.

In the resin pipe, unlike the metal pipe, it is difficult to control the gap accuracy like the metal pipe. However, if the gap interval is controlled to be narrow, the present invention can be applied in the same manner as the metal pipe. However, in the resin cage, there is an adhesive that melts and bonds the material of the adhesive surface of the resin tube, and in this case, it is difficult to twist the gap interval.

Claims

A pipe having a conical taper surface whose end is reduced in diameter toward the front side, a pipe having a funnel-shaped taper surface whose end is reduced in diameter toward the back side, and the taper surfaces are connected by an adhesive. The tapered surfaces have the same inclination angle and are in the range of 3 to 8 degrees, and are concentrically arranged on the inner peripheral side of the tube on the tapered surface from 0.05 mm to 0 mm. An inner peripheral side protrusion that protrudes in a ring shape within a height range of 3 mm and abuts against the taper surface that directly faces, and an adhesive press-fitting hole that penetrates the taper surface from the outer periphery of the tube having the funnel-shaped taper surface And a pipe connection structure characterized by that.
2. The pipe connection structure according to claim 1, wherein the ring-shaped protrusion is provided on a pipe side having the conical tapered surface.
2. The pipe connection structure according to claim 1, wherein the protrusion is on the conical taper surface and protrudes in a ring shape from the conical taper surface toward the outer peripheral side of the tube and abuts against the taper surface facing the conical taper surface. A pipe connection structure characterized in that is provided.
2. The pipe connection structure according to claim 1, wherein a cylindrical sleeve that is externally fitted in a range on both sides centering on a position where the pipes are attached to each other, and a space between the sleeve and the outer peripheral surface of the pipe are filled. A connecting structure for a tube, characterized by comprising a bonded adhesive.
5. The pipe connection structure according to claim 4, wherein an adhesive press-fitting hole penetrating from the outer periphery to the inner periphery of the sleeve is opened.
4. The pipe connection structure according to claim 3, wherein a radial groove is provided on the outer peripheral side protruding portion or a tapered surface facing the outer peripheral side protruding portion. .
2. The pipe connection structure according to claim 1, wherein the pipe is in an inner peripheral side where the pipes come into contact with each other, and a ring-like groove is provided on any one of the pipes, and is inserted into the ring-like groove. A pipe connection structure comprising an O-ring.
2. The pipe connection structure according to claim 1, wherein a distal end portion of the pipe is quenched.
2. The tube connection structure according to claim 1, wherein any one of the tubes has a flange portion at an end opposite to an end bonded to the other tube. .
10. The pipe connection structure according to claim 9, further comprising a sleeve that is externally fitted in a state of straddling the two pipes and is bonded to an outer peripheral surface of both pipes with an adhesive.
8. The pipe connection structure according to claim 7, wherein one of the pipes is provided with a funnel-shaped tapered surface at both ends, and the ring-shaped groove is provided at an inner peripheral side position. A pipe connection structure characterized by being a joint pipe having an O-ring inserted into a groove and connected to another pipe.
12. The pipe connection structure according to claim 11, further comprising: a sleeve that is externally fitted in a state of straddling the joint pipe and another pipe, and has a sleeve bonded to the outer peripheral surface of both pipes by an adhesive. Construction.
A pipe having a conical taper surface whose end is reduced in diameter toward the front side, a pipe having a funnel-shaped taper surface whose end is reduced in diameter toward the back side, and the taper surfaces are connected by an adhesive. The tapered surfaces have equal inclination angles and are in the range of 3 to 8 degrees, and each of the conical and funnel-shaped tapered surfaces has an annular end surface perpendicular to the tapered surface. Is provided on the inner circumferential side continuously, and a ring groove into which an O-ring is fitted is provided on one annular end surface, and the annular end surface continuing to the funnel-shaped tapered surface is conical. The ring-shaped end faces are opposed to each other in a height range of 0.05 mm to 0.3 mm via an O-ring, and the funnel-shaped taper. Pipe with face Connection structure of the tube, characterized in that the press-fit hole of the adhesive penetrating from the peripheral to the tapered surface is provided.