JP2017223277A - Pipe joint structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pipe joint structure capable of making a pipe joint in an axial dimension compact, enhancing reliability of a pipe joint structure, and especially suitable even for refrigerant.SOLUTION: A pipe joint structure includes a cylindrical sleeve 5 for compression deformation on the outer peripheral surface of which a plurality of recess peripheral grooves 8 is provided, and which plastically deforms so that when a bag nut 3 is screwed to a joint body 1, a groove bottom thin wall part of the recess peripheral groove projects radially inward with axial compressive force, and thereby is bitten from an outer peripheral surface side of an inserted pipe P to prevent looseness. An inner peripheral surface 10 for sleeve holding, which corresponds to the outer peripheral surface of the sleeve for compression deformation, is provided in the joint body.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a pipe joint structure.

Flare joints have been used as a kind of pipe joints for a long time, but in piping work, it was necessary to perform flare processing at the pipe end in the field, which hindered the improvement of piping work efficiency.
Therefore, the present inventor has solved the above-mentioned drawbacks of the flare joint and has a pipe joint structure with a small number of parts. As shown in FIGS. Numerous inventions have been proposed for pipe joint structures having a sleeve 38 (see, for example, Patent Documents 1 and 2).
That is, as shown in FIGS. 9 (B) and 10 (B), a joint body 40 having a male tapered surface 39 and a male screw 41, which are gradually reduced in diameter in the distal direction, and the male screw 41 are screwed. A cap nut 42, and the compression deformation sleeve 38 housed in the cap nut 42. Further, the compression deformation sleeve 38 has a concave circumferential groove 43 on the outer periphery and a female tapered surface 44 corresponding to the male tapered surface 39 on the inner end.
When the cap nut 42 is screwed into the joint body 40, as shown in FIGS. 9 (B) and 10 (B), an axial force is received, and the width of the concave circumferential groove 43 is reduced while the concave circumference is reduced. The groove bottom thin wall portion 43A is plastically deformed radially inward and bites in from the outer peripheral surface of the inserted pipe P (as shown in FIG. The female taper surface 44 is in pressure contact with each other to form a sealing action.

Japanese Patent No. 5276215 Japanese Patent No. 5523612

The pipe joint structures shown in Patent Document 1 and Patent Document 2 (FIGS. 9B and 10B) are excellent inventions that can replace conventional flare joints.
However, it has been found that the pipe joints shown in FIGS. 9B and 10B have the following drawbacks. That is, (i) If the axial center line of the nut portion 40A of the joint body 40 is assumed to be the axial center line L _{0 of the} joint body 40, the axial dimension from the center line L ₀ to the outer end face 42A of the cap nut 42 Disadvantages that X ₀ is large, (ii) Disadvantage that pipe P has a large space for piping with many rounded bends due to large X ₀ , and (iii) Cap nut 42 is a material saving Although brass forgings from manufacturability or the like is used in principle, by the size X ₀ is large, there is a disadvantage of such defect rate such as cracks (crazing) is increased.
9B and FIG. 10B are used in a variety of environments, as shown in FIG. 15 (along the axis) under certain circumstances and conditions. It has been found that an axial crack (break) 45 may occur in a region Z (see FIG. 16) in the vicinity of the female taper surface 44 of the sleeve 38.
“A certain environment” refers to an environment where ammonia (gas / water) exists, such as toilets, septic tanks, garbage dumps, chemical factories, etc. “A certain condition” refers to a compression deformation sleeve 38. As a result of the inventor's investigation, experiment, and research, it has been gradually investigated that is made of brass and its manufacturing method is related (as will be described later).

  Accordingly, an object of the present invention is to reduce the axial dimension of the pipe joint, improve the reliability of the pipe joint structure, and provide a pipe joint structure that is particularly suitable for refrigerants.

  In the present invention, a plurality of concave circumferential grooves are provided on the outer peripheral surface, and the groove bottom thin wall portion of the concave circumferential grooves receives a compressive force in the axial direction when the cap nut is screwed into the joint body. In a pipe joint structure provided with a cylindrical compression deformation sleeve that is plastically deformed so as to protrude radially inward and that bites in from the outer peripheral surface side of the inserted pipe and prevents it from being removed. An inner peripheral surface for holding a sleeve corresponding to the outer peripheral surface of the sleeve is provided on the joint body.

In addition, 80% or more of the total length of the compression deformation sleeve in the compression completion state is inserted into the sleeve holding inner peripheral surface of the joint body, and all of the plurality of concave circumferential grooves are completely compressed. Under the condition, the sleeve is surrounded by the inner peripheral surface for holding the sleeve.
Further, the joint body has a male cylinder on the outer periphery and a regulating cylindrical wall portion having the inner peripheral surface for holding the sleeve on the inner periphery, and the female screw of the cap nut is screwed into the male screw. In the compressed state, the compression deformation sleeve is surrounded by a double surrounding structure including the restriction cylindrical wall portion and the cap nut.
The cap nut is in pressure contact with only the outer end surface in the axial direction of the compression deformation sleeve, and is always in a non-contact state with the outer peripheral surface of the compression deformation sleeve.

  According to the present invention, the compression deformation sleeve has a rush-like structure deep into the inside of the joint body, and the axial dimension as a pipe joint is remarkably reduced, so that the compactness can be achieved.

It is sectional drawing which shows one Embodiment of this invention and shows a cap nut untightened state. It is sectional drawing which shows a cap nut fastening completion state (compression completion state of a sleeve). It is sectional drawing which shows an example of the sleeve for compression deformation. FIG. 4 is an enlarged explanatory view of a main part of FIG. It is sectional drawing which shows an example of a coupling main body. It is principal part sectional drawing which shows a state which inserts a pipe and a cap nut is not fastened. FIG. 3 is an enlarged view of a main part of FIG. 2. It is operation | movement explanatory drawing in a cap nut fastening completion state. It is principal part sectional drawing for comparing the Example of this invention, and a prior art example in a cap nut untightened state. It is principal part sectional drawing for comparing the Example of this invention, and a prior art example in a cap nut fastening completion state. It is sectional drawing which shows the various Example of a concave groove. It is principal part sectional drawing which shows the various Example of the inner-end site | part of the sleeve for compression deformation. It is sectional drawing of the cap nut untightened state which shows other embodiment of this invention. It is a principal part enlarged view for demonstrating the trouble of a prior art example. It is an isometric view explanatory drawing of the sleeve for compression deformation for demonstrating the problem of a prior art example. It is principal part sectional explanatory drawing which shows generation | occurrence | production and progress of the crack in a prior art example.

Hereinafter, the present invention will be described in detail based on the illustrated embodiment.
1-7, FIG. 9 (A), and FIG. 10 (A) show one embodiment of the present invention. The pipe joint structure according to the present invention includes a joint body 1 with a male thread, a cap nut 3 with a female thread, and a compression deformation sleeve 5.

In the embodiment shown in FIGS. 1, 2, and 5, the pipe joint structure of the present invention has a bilaterally symmetric shape with respect to the axial center line L ₀ . The outer surface of the joint body 1 has a work tool gripping portion 26 such as a polygon at the center, and male screws 1A and 1A on both sides in the axial direction so that the cap nuts 3 and 3 are screwed. Further, the joint body 1 is formed with a through hole 11 along the axis L ₁ .
The compression deformation sleeve 5 is provided with a plurality of (two in the illustrated example) concave circumferential grooves 8 and 8 on the outer peripheral surface 7, and the axial direction of the cap nut 3 is screwed into the joint body 1. In response to the compressive force F (see FIGS. 6 and 7), the groove bottom thin wall portion 9 of the concave circumferential grooves 8 and 8 is plastically deformed so as to protrude radially inward, as shown in FIGS. A cylindrical shape that bites in from the outer peripheral surface 12 side of the inserted pipe P and prevents it from being removed.

  The joint body 1 has a sleeve holding inner peripheral surface 10 corresponding to the outer peripheral surface 7 of the compression deformation sleeve 5. That is, in the conventional example, as shown in FIGS. 9 (B) and 10 (B), the sleeve 38 exists outside (in the axial direction) the joint body 40, but the pipe joint according to the present invention. In the structure, the sleeve 5 has a structure and shape that penetrates deeply in the axial direction, and the sleeve 5 is inserted deeply into the inner peripheral surface 10 for holding the sleeve. 11), and is fitted while corresponding to the inner peripheral surface 10 for holding the sleeve.

As shown in FIG. 5, the through-hole 11 has an inner ridge portion 2 at a central position in the axial direction along the axis L ₁ , and a sleeve is provided on each of the left and right sides of the inner ridge portion 2. Holding inner peripheral surfaces 10, 10 are formed. Sectional shape of the inner ridge 2 is composed of a quadrature wall portion 2A and the Taigata portion 2B orthogonal to the axis L _1, the entire cross section of the inner ridges 2 is a flask type.
The inner end face 2C of the inner protrusion 2 forms part of a flow path hole as shown in FIGS. 2 and FIG. 7, the diameter (of the flow path) formed by the inner end face 2C is substantially equal to the inner diameter of the sleeve 5 and the inner diameter of the pipe P.
Further, the inner ridge portion 2 will be described. A tip edge portion 13 having a triangular cross section is formed by the oblique side (gradient surface) 2E of the trapezoidal portion 2B and the inner end surface 2C corresponding to the bottom side of the trapezoidal portion 2B. ing.

Next, the sleeve 5 is housed in an internal housing space S formed by one side surface (the oblique side 2E, etc.) of the inner protrusion 2 of the joint body 1 and the inner peripheral surface 10 for holding the sleeve (FIGS. 1 and 2). FIG. 6 and FIG. 7). Further, the sleeve 5 has a female taper surface 14 for pressure contact sealing at one end 23 thereof, and the female taper surface 14 corresponds to the inclined surface (slope side) 2E of the inner protrusion 2 of the joint body 1.
Assuming that the total length of the sleeve 5 in the compressed state is L ₅ , as shown in FIGS. 2 and 7, 80% to 100%, preferably 85% to 99%, more desirably 88% of the total length L _5. The range of ˜96% corresponds to the sleeve holding inner peripheral surface 10 of the joint body 1 (inserted).
In other words, if the axial length (depth) of the sleeve holding inner peripheral surface 10 shown in FIGS. 5 and 7 is L ₁₀ ,
0.80 ・ L ₅ ≦ L ₁₀ ≦ 1.00 ・ L ₅
Preferably,
0.85 ・ L ₅ ≦ L ₁₀ ≦ 0.99 ・ L ₅
More preferably,
0.88 ・ L ₅ ≦ L ₁₀ ≦ 0.96 ・ L ₅
Set as follows.

Further, all of the plurality of concave circumferential grooves 8 and 8 are surrounded by the sleeve holding inner peripheral surface 10 under the sleeve compression completion state. That is, when the sleeve compression is completed, all the concave grooves 8 and 8 are inside the joint body 1, and the outer peripheral surface portion in the vicinity of the concave groove 8 that is most likely to undergo plastic deformation in the radially outward direction is the sleeve holding. as shown in use the inner peripheral surface 10 a vector F ₈ in FIG. 7, it is restricted, the concave peripheral groove 8 near does not deform excessively in the radial outward direction. As a result, the groove bottom thin wall portion 9 is surely bitten into the pipe P while being deformed into a U shape or a V shape.

If it demonstrates additionally, it can be said that the coupling main body 1 is provided with the control cylindrical wall part 25 which has the external thread 1A in an outer periphery, and has the inner peripheral surface 10 for sleeve holding in an inner periphery. And the regulation cylindrical wall part 25 makes the effect | action which regulates that the sleeve 5 inserted in the inside deform | transforms into a radial outward direction excessively.
In addition, as shown in FIGS. 2 and 7, the sleeve 5 is composed of the restriction cylindrical wall portion 25 and the cap nut 3 in a compression completed state in which the female screw 3 </ b> A of the cap nut 3 is screwed into the male screw 1 </ b> A. Surrounded by the heavy surrounding structure W.

1 to 7, the cap nut 3 is in pressure contact only with the outer end surface 27 in the axial direction of the sleeve 5 (as indicated by the arrow F), and is not in contact with the outer peripheral surface 7 of the sleeve 5. Always in a non-contact state. Therefore, the rotational torque when the cap nut 3 is screwed and the sleeve 5 is compressed and plastically deformed can be small, and the rotation operation with the work tool can be easily performed. In addition, at that time, the sleeve 5 does not rotate together with the rotation of the cap nut 3. In connection with this, the effect that the pipe P does not rotate together (continuous rotation) can also be expected.
In this way, the rotational torque applied to the cap nut 3 by the work tool is effectively utilized intensively for the compressive plastic deformation of the sleeve 5 in the axial direction. The friction reducing intervention sleeve material 46 in the conventional pipe joint structure shown in FIGS. 9B and 10B can be omitted.

  In the sleeve 5, a cylindrical insertion recess 28 into which the tip of the pipe P is inserted is formed by the insertion tube portion 21. This insertion cylinder part 21 corresponds to the tip inner peripheral surface of the pipe P in the inserted state. A cylindrical insertion recess 28 is formed in a distal end opening shape by the thick cylindrical sleeve body portion 6 having the concave circumferential grooves 8 and 8 of the sleeve 5 and the thin insertion tube portion 21.

As shown in FIGS. 1 to 6, when the pipe P is inserted into the recess 28 and then the cap nut 3 is screwed into the male screw 1A of the joint body 1, the axial force F is received from FIG. As shown in FIG. 7 (FIG. 2), the concave circumferential groove bottom thin wall portion 9 is plastically deformed and inserted in the radial inward direction while the width dimension W ₈ (see FIG. 3) of the concave circumferential groove 8 is reduced. At this time, the inner cylindrical portion 21 prevents the pipe P from escaping in the diameter-reducing direction (excessive deformation). Thus, in the state of FIGS. 2 and 7, the pipe P is completely prevented from being removed, and the female taper surface 14 is strongly pressed against the inclined surface (slanted side) 2 </ b> E as a male taper so as to have a sealing action. Make.

As shown in FIGS. 3 and 4, the sleeve 5 has an end 23 thereof, from the inner peripheral edge 14 </ b> A of the female tapered surface 14, via a small U-shaped recess 15 (the female tapered surface 14. A reverse taper surface 16 is formed. The reverse taper shape means that the female taper surface 14 gradually increases in diameter toward one axial direction L ₂₀ while gradually decreasing in diameter in one axial direction.
A hooking claw portion 20 is formed by the reverse tapered surface 16 and the end portion 18 of the inner peripheral surface 17A of the sleeve hole portion 17 (see FIG. 4).

The small claw portion 20 of the sleeve 5 is locked (hooked) to the tip edge portion 13 of the inner protrusion 2 of the joint body 1. That is, in the cap nut tightening completion state (connection completion state) shown in FIGS. 2 and 7, the hooking claw portion 20 is in the radial direction with respect to the tip edge portion 13 of the inner protrusion 2 of the joint body 1. It is caught from the inside. In the untightened state, the tip edge portion 13 has an axially orthogonal plane portion in an annular shape as illustrated in FIG. 6, but in the state in which the cap nut is tightened in FIGS. strongly pressed against the vicinity of the small U-shaped recess 15 (see FIG. 6), to the extent that another gap is eliminated, becomes crushing shaped, as shown in FIG. 8, the vector F ₁₃ is, the small U-shaped recess 15 Acts in the vicinity.

On the other hand, the female taper surface 14 is rounded with a large radius of curvature R in the example of FIG. 4, but in the state where the cap nut is tightened in FIGS. The sleeve outermost end portion 5A on the one end portion 23 side of the sleeve 5 tends to be deformed outward in the radial direction by being strongly pressed and deformed so as to be deformed so as to approach a linear taper shape. To do. However, the arrows (vectors) F ₁₀ in FIG. 8 is added at the peripheral surface 10 for holding the sleeve, it is possible to prevent a deformation in the radial outside direction of the endmost 5A. As shown in FIG. 8, the vector F ₂ acts from the inclined surface 2E toward the female tapered surface.

8 Te at two of the vector F _13, F _2, and X direction parallel to the axis L _1, the direction Y perpendicular to the axis L _1, and each decomposition, F _13x, F _{13y, Let} F _2x and F _2y .
(F _2x + F _13x ) is a reaction force against the tightening force applied in the X direction by the cap nut 3. F _13y is a force in the Y direction (radial inward direction) applied from the tip edge portion 13 to the hooking claw portion 20 (and the concave portion 15), and F _2y is a pressure contact state between the gradient surface 2E and the female taper surface 14 This is a force in the Y direction (radial outward direction) applied from the inclined surface 2E to the female tapered surface 14.

In the conventional example shown in FIG. 14, F ₃₉ , F _39x , and F _39y indicate the following vectors, respectively.
That is, F ₃₉ : force (vector) applied from the male tapered surface 39 to the female tapered surface 44
F _39x : F ₃₉ component force (vector) in the X direction parallel to the axis L ₃₈
F _39y : F ₃₉ component force (vector) in the Y direction perpendicular to the axis L ₃₈
Comparing FIG. 14 (conventional example) with FIG. 8 showing the pipe joint structure according to the present invention, the following formulas 1, 2, and 3 are established.
F _2x + F _13x = F _39x [Formula 1]
F ₂ <F ₃₉ [Formula 2]
F _2y <F _39y [Formula 3]

In the conventional compression deformation sleeve 38, the vector F _39y shown in FIG. 14 has a very large value. Therefore, in FIG. 15, a large circumferential tension T ₄₅ is present in the vicinity of the female taper surface 44. It is presumed that a crack (break) 45 has occurred in the region Z after the completion of the cap nut tightening and continued to act.
In particular, in a certain environment where ammonia exists in toilets, septic tanks, garbage collection sites, chemical factories, etc., as shown by arrow Az shown in FIG. When the sleeve 38 is made of brass, and the drawn circular pipe (pipe) is machined (as it is, without heat treatment). -For example, the present inventor has made it clear through field surveys and experiments that a crack 45 as shown in Fig. 15 occurs after a period of use of several months.

Further, as a result of research and experiment, the crack 45 is not from the outside of the sleeve 38, but from the middle position of the female tapered surface 44, as shown by dots in FIGS. In other words, it has been found that it develops from the inside toward the outside – the radial outward direction.
The reason is as follows. (i) A large amount of residual stress remains in the drawn pipe (pipe) made of brass when it is greatly stretched in the axial direction. (ii) It is used without heat treatment even if machine processing is performed thereafter. For this reason, the residual stress remains in the sleeve as it is. (Iii) As shown in FIG. 15 as a schematic explanatory diagram U, the brass crystal (structure) made of Cu and Zn is formed in the axial direction by the above drawing process. Therefore, cracks 45 develop in the longitudinal cross-sectional direction of the sleeve sequentially from FIGS. 16 (A) to 16 (C), and finally FIG. 15 and FIG. 16 ( As shown in FIG. 14C, the sealed gas reaches the outer peripheral surface of the sleeve and leaks to the outside. (Iv) In addition, the radially outward (Y direction) vector F _39y shown in FIG. By continuing to act, the crack 45 is combined with the above (i) (ii) (iii) and the crack 45 is shown in FIG. A) The point is developed in the order of (B) and becomes the state shown in FIG. 16 (C) and FIG.

In the present invention, in order to significantly reduce the vector F _39y in the radial outward direction (Y direction) in the conventional example of FIG. 14, large vectors F ₁₀ and F _13y in the radial inward direction are used as shown in FIG. It can be said that it was generated by the sleeve holding inner peripheral surface 10 of the joint body 1 and the (small) hooking claw portion 20.
The axial outward direction (Y direction) vector F _2y shown in FIG. 8 can be remarkably reduced, so that the circumferential tension T ₄₅ (as shown in the conventional example of FIG. 15) is sufficiently reduced. The cracks shown in Fig. 16 can be reliably prevented.

By the way, the concave circumferential groove 8 shown in FIGS. 11A, 3 and 6 has a cross-sectional shape of a home base type. Therefore, a force F for compressing in the axial direction as shown in FIGS. Therefore, the vector sum (F _2x + F _13x ) shown in FIG. 8 becomes small, and the vector F _2y decreases accordingly. Therefore, there is an advantage that the occurrence of cracks can be further prevented.
However, in the present invention, the cross-sectional shape of the concave circumferential groove 8 is a pen tip shape as shown in FIG. 11 (B), a semicircular shape as shown in FIG. 11 (C), a U shape as shown in FIG. V-shape and square shape are free.

  As described above, the compression deformation sleeve 5 has the reverse tapered surface 16 formed from the inner peripheral end edge portion 14A of the female tapered surface 14 through the small U-shaped concave portion 15, and the end portion of the sleeve hole inner peripheral surface 17A. 18 and a reverse taper surface 16 form a hooking claw portion 20 that is engaged with the tip end edge portion 13 inside the joint body 1, and has a simple structure. Even if residual stress remains inside, ammonia It is possible to effectively prevent the crack 45 in the “certain environment” in which there is, etc. For example, it is suitable for connection of refrigerant pipes, has high reliability, and can reliably prevent external leakage of the refrigerant over a long period of time.

  Next, FIG. 14 is an enlarged explanatory view of the main part of FIG. 10B (showing a conventional example). In FIG. 10B and FIG. 14, the occurrence of the crack 45 shown in FIGS. Where the female taper surface 44 of the sleeve 38 is very close to the outside of the fitting (atmosphere side) and easily from the threaded portion of the cap nut 42, as indicated by the arrow Az (see FIG. 14). As described above, since the air enters, the problem of the crack 45 is likely to occur.

On the other hand, in the present invention, as shown in FIGS. 2, 7, and 10A, the place where the possibility of occurrence of cracking is highest—the female tapered surface 14 of the sleeve 5 is the joint body 1. The corrosive gas such as ammonia as shown by an arrow Az shown in FIG. 14 is difficult to reach. Also from such a structure, the occurrence of the conventional crack 45 can be reliably prevented.
Furthermore, in the example shown in the figure, two sealing materials 29 and 30 are attached, which further prevents the invasion of corrosive gas such as ammonia and prevents the conventional crack 45 from occurring. . However, depending on the environment in which the pipe joint is installed, the sealing materials 29 and 30 may be omitted.

  The shape of the one end portion 23 on the back side of the sleeve 5 shown in FIGS. 1 to 8 is shown in FIG. 12 (A). In the present invention, it is designed as shown in FIGS. 12 (B) and (C). You are free to change. That is, FIG. 12 (B) is the same as the conventional sleeve 38 of FIGS. 9 (B) and 10 (B), and FIG. 12 (C) is a simple axial center orthogonal end 23. However, the shape of the end 23 is also free.

In another embodiment shown in FIG. 13, has a tapered male thread 31 on the left side of the center line L _0, the right side of the center line L ₀ is the same configuration as FIGS. 1-12 already described. The same reference numerals are the same as those in FIGS. 1 to 12, and a duplicate description is omitted. However, in FIG. 13, the inner ridge portion 2 shown in FIGS. 1 and 2, etc. does not exist, and the channel hole portion 32 is located on the left side of FIG. It is formed in a penetrating shape.
In addition to the illustrated embodiments described above, an elbow type and a tube type can be used freely. In short, at least a portion having a configuration as shown in FIGS. 9A and 10A is provided. It is enough to have one.

Next, in FIG. 9 and FIG. 10, the present invention and the conventional example will be compared again, and the difference in configuration, the difference in operation and effect, and the like will be additionally described.
According to the pipe joint structure according to the present invention, the sleeve holding inner peripheral surface 10 of the joint main body 1 corresponds to the outer peripheral surface 7 of the sleeve 5, and the sleeve 5 penetrates deeply into the joint main body 1. Therefore, the axial dimension (length dimension) X ₁ from the axial center line L ₀ to the outer end surface 3E of the cap nut 3 is the sleeve uncompressed state (see FIG. 9) and the compression completed state (see FIG. 10). In any case, the axial direction dimension (length dimension) X ₀ of the conventional pipe joint in which the sleeve 38 is outside the joint body 40 and is held inside the cap nut 42, It can be remarkably reduced and can be greatly downsized in the axial direction (see FIG. 9A, FIG. 10A, FIG. 9B, and FIG. 10B).

Further, as shown in FIG. 10 (A), more than 80% of the total length L ₅ of the compression completion state of the sleeve 5, is inserted into the sleeve holding inner peripheral surface 10 of the joint main body 1, deep enough, the joint body by first sleeve 5 inside invading the axial dimension X ₁ is sufficiently reduced, it may work to compact.
In addition, all of the plurality of concave circumferential grooves 8 and 8 are surrounded by the sleeve holding inner peripheral surface 10 of the joint body 1 under the compression completion state (see FIG. 10A). As shown in FIG. 7, the vicinity of each concave circumferential groove 8 receives a pressing force in the radial inward direction as in the vector F ₈ , and the groove bottom thin wall portion 9 is surely formed in a U shape or a V shape in the radial inward direction. It bites into the outer peripheral surface of the pipe P while being deformed. The number of the concave circumferential grooves 8 may be three or more (not shown).

Further, the joint body 1 includes a male cylinder 1A on the outer periphery and a regulation cylindrical wall portion 25 having the inner peripheral surface 10 for holding the sleeve on the inner periphery. Since the compression deformation sleeve 5 is surrounded by the double surrounding structure W composed of the restriction cylindrical wall portion 25 and the cap nut 3 in the compression completed state in which 3A is screwed, the outer peripheral surface of the sleeve 5 is Is held in the radial inward direction, receives the radial inward vector indicated by the arrow F _{8 in} FIG. 7, and the groove bottom thin wall portion 9 is reliably deformed in the radial inward direction while the pipe P Can be pulled out.

Further, in the conventional pipe joint structure, as shown in FIGS. 9B to 10B, when the cap nut 42 is screwed, the sleeve 38 has not only the outer end surface but also the outer peripheral surface. Even if it is pressed against the inner peripheral surface of the nut 42 and the frictional resistance is reduced by the interposed sleeve material 46 as shown in FIGS. 9B and 10B, as the cap nut 42 rotates, The sleeve 38 and the pipe P are co-rotated (continuous), causing a problem in the pipe P connected to the pipe, and also rotating slippage between the male taper surface 39 and the female taper surface 44. In some cases, the sealing property of the pressure contact part deteriorates.
However, in the present invention, the cap nut 3 is in pressure contact with only the outer end surface 27 in the axial direction of the compression deformation sleeve 5 and is always in non-contact with the outer peripheral surface 7 of the compression deformation sleeve 5. Therefore, such a problem of the conventional example does not occur, the co-rotation (continuous rotation) of the sleeve 5 can be prevented, and the twist due to the co-rotation (continuous rotation) of the pipe P can also be prevented. Moreover, even if the conventional sleeve member 46 for reducing friction is omitted, the torque for rotating the cap nut 3 with the work tool is small, and the screwing operation can be performed easily and quickly.

9A and 9B, the cap nut 3 has a significantly shorter axial dimension (compact) than the conventional cap nut 42, and the cap nut When forging is made of a brass forged product, cracks (cracks) do not occur during forging, the rate of occurrence of defects is significantly reduced, and forging can be performed easily.
Further, in the conventional example, the sleeve 38 is held inside the cap nut 42 and is plastically deformed as shown in FIGS. 9 (B) to 10 (B). In the case of screwing of the female thread of the nut 42, rattling is likely to occur, and the axis of the cap nut 42 is likely to be unevenly distributed with respect to the axis of the joint body 40. In some cases, the shaft is eccentric and the female taper surface 44 is not uniformly pressed 360 ° against the male taper surface 39, resulting in poor sealing. Moreover, for the same reason, there is a possibility that problems such as a decrease in sealing performance and a decrease in pulling force may occur without the groove bottom thin wall portion 43A being uniformly deformed into a U-shape or a V-shape in a uniform manner of 360 °.

  On the other hand, in the present invention, the sleeve 5 is fitted to the straight inner peripheral surface 10 formed on the joint body 1 and is compressed and deformed, so that all such conventional problems are solved. Both shaft centers of the sleeve 5 and the joint body 1 coincide with each other with high accuracy, and the female taper surface 14 is in close pressure contact with the inclined surface 2E uniformly at 360 °, and the sealing performance is stable and good. In addition, the groove bottom thin wall portion 9 in a U-shape or V-shape becomes a 360 ° uniform and accurate deformed shape, and the sealing performance is further stabilized and excellent. Also, the pulling force of the pipe P is stable and large.

DESCRIPTION OF SYMBOLS 1 Joint body 1A Male screw 3 Cap nut 3A Female screw 5 (For compression deformation) Sleeve 7 Outer peripheral surface 8 Concave groove 9 Groove bottom thin wall
10 Inner peripheral surface for holding sleeve
12 Outer surface
25 Restricted cylindrical wall part F Compressive force L ₅ Overall length P Pipe W Double enclosed structure

Claims (4)

A plurality of concave circumferential grooves (8) (8) are provided on the outer peripheral surface (7), and when the cap nut (3) is screwed into the joint body (1), the axial compression force (F) In response, the groove bottom thin wall portion (9) of the concave circumferential groove (8) is plastically deformed so as to protrude radially inward, and bites in from the outer peripheral surface (12) side of the inserted pipe (P). In the pipe joint structure provided with the cylindrical compression deformation sleeve (5) to be secured with
A pipe joint structure characterized in that a sleeve holding inner peripheral surface (10) corresponding to the outer peripheral surface (7) of the compression deformation sleeve (5) is provided in the joint main body (1). 80% or more of the total length (L ₅ ) of the compression deformation sleeve (5) in the compressed state is inserted into the sleeve holding inner peripheral surface (10) of the joint body (1), and more than one 2. The pipe joint structure according to claim 1, wherein all of the concave circumferential grooves (8) and (8) are surrounded by the sleeve holding inner circumferential surface (10) in a compressed state. The joint main body (1) includes a regulation cylindrical wall (25) having a male screw (1A) on the outer periphery and the inner peripheral surface (10) for holding the sleeve on the inner periphery,
In the compression completion state in which the female screw (3A) of the cap nut (3) is screwed into the male screw (1A), the compression deformation sleeve (5) includes the restriction cylindrical wall (25) and the bag. 3. A pipe joint structure according to claim 1, wherein the pipe joint structure is surrounded by a double surrounding structure (W) comprising a nut (3).   The cap nut (3) is in pressure contact with only the outer end surface (27) in the axial direction of the compression deformation sleeve (5), and is always against the outer peripheral surface (7) of the compression deformation sleeve (5). The pipe joint structure according to claim 1, 2 or 3, which is in a non-contact state.

Images