Pipe joint

Abstract

To provide a pipe joint that has strong pipe withdrawal resistance, is excellent in durability, and has a home base-shape recessed groove.SOLUTION: A home base-shape recessed groove 9 formed in a compressive deformable sleeve 7 has a large straddle angle θ, where a deep part tip 9A has a round shape with a specified large radius R1.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a pipe joint.

Background Art

[0002] The pipe joint having the structure shown in FIGS. 11 to 13 was once proposed by one of the present inventors and has been patented (see Patent Document 1). In particular, as a refrigerant pipe, it has good workability for pipe connection, and can surely prevent external leakage of refrigerant gas. It has received favorable reviews in the industry and has been widely popularized.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the conventional pipe joint shown in FIGS. 11 to 13 has the following problems. That is, the outer peripheral concave grooves 59A and 59B of the sleeve 62 have a "home base type" like a baseball home base, and each corner is (sharply) angular. In particular, the corner 60 at the tip of the inner part of the concave grooves 59A and 59B has a sharp shape (see FIG. 13). Therefore, when the nut 40 is screwed in from the states of FIGS. 11 and 13, the pipe connection completed state shown in FIG. 12 is obtained. However, cracks may occur from the original sharp corner 60. In particular, there is a risk of cracks due to fatigue after long-term use. In addition, due to the angular home base type, there is a problem that the plastic deformation operation when the near-wall part of the corner 60 of each concave groove 59A and 59B bites into the outer peripheral surface of the pipe P lacks a little smoothness.

[0005] Therefore, an object of the present invention is to solve such problems and prevent cracks from occurring in the inner part of the concave groove of the sleeve during the sleeve compression operation or after a long service period (after connection is completed). Furthermore, an object of the present invention is to provide a pipe joint that can exhibit a large pull-out resistance by smoothly plastically deforming the concave groove and deeply and surely biting into the outer peripheral surface of the pipe.

Means for Solving the Problems

[0006] The present invention includes a joint body with a male thread, a nut screwed onto the male thread of the joint body, and a sleeve housed in the internal storage space of the nut and capable of being plastically deformed by compression as the nut advances; the sleeve has a cross-sectional home-base type concave groove on the outer peripheral surface near the tip, and the tip of the inner part of the cross-sectional home-base type concave groove is formed in an arc shape with a predetermined radius.

[0007] Also, the opening angle in the cross-section of the tip of the inner part of the cross-sectional home-base type concave groove is set such that 90° ≤ θ ≤ 120°. Or, the opening angle in the cross-section of the tip of the inner part of the cross-sectional home-base type concave groove is set such that 100° ≤ θ ≤ 115°. Also, the predetermined radius R of the tip of the inner part of the cross-sectional home-base type concave groove 1 is set such that, if the groove width dimension of the concave groove is W 9 then 0.11·W 9 ≤ R 1 ≤ 0.30·W 9 as described above.

[0008] Also, only a single concave groove is formed in the sleeve, and further, the sleeve has a cross-sectional rectangular seal groove on the inner peripheral surface at an axially inner position than the concave groove, and an elastic sealing material is installed in the seal groove. Also, the inner insertion cylinder part inserted into the inner peripheral surface of the tip of the pipe to be inserted is omitted.

[0009] Further, the cross-sectional shape of the cross-sectional home-base type concave groove is made asymmetrical left and right by making the dimension from the inner side edge on the base end side of the sleeve to the dimension to the outer side edge on the tip end side of the sleeve different with respect to the left-right dividing virtual line passing through the deepest point at the tip end of the depth portion.

[0010] In addition, the pipe joint according to the present invention includes a joint body with a male thread, a nut screwed onto the male thread of the joint body, and a sleeve that is housed in the internal storage space of the nut and can be plastically deformed by compression by screwing in the nut; the sleeve has a cross-sectional home-base type concave groove on the outer peripheral surface near the tip; on the inner peripheral surface of the sleeve, two annular inner peripheral shallow concave grooves are formed axially inward and axially outward from the axial position of the tip end of the depth portion of the concave groove. Further, the longitudinal cross-sectional shape of the pipe biting projection formed by plastically deforming the sleeve by applying an axial compressive force in the state where the pipe is not inserted is a Mount Fuji type having a wide horizontal plane obtained by horizontally cutting and removing the peak top; moreover, the left and right middle bellies of the Mount Fuji type have a shape provided with low secondary peaks forming valleys.

[0011] In addition, the pipe joint according to the present invention includes a joint body with a male thread, a nut screwed onto the male thread of the joint body, and a sleeve that is housed in the internal storage space of the nut and can be plastically deformed by compression by screwing in the nut; the sleeve has a cross-sectional home-base type concave groove on the outer peripheral surface near the tip; the concave groove has a cross-sectional shape in which a virtual first home-base shape with a large opening angle and a virtual second home-base shape with a small opening angle are superimposed; the virtual first home-base shape and the virtual second home-base shape are superimposed with the groove width dimension set to be the same, and the tip end of the depth portion of the virtual second home-base shape with the small opening angle penetrates deeper than the tip end of the depth portion of the virtual first home-base shape with the large opening angle.

[0012] Further, in the superimposed cross-sectional shape, side small concave depressions for reducing the compression resistance during compression plastic deformation are formed at the left and right side corners of the concave groove. Further, in the above-described superimposed cross-sectional shape, the concave groove has a large leg-opening angle portion and a small leg-opening angle portion.

[0013] Further, the leg-opening angle of the large leg-opening angle portion is set to 110° to 160°; the leg-opening angle of the small leg-opening angle portion is set to 80° to 100°. Further, the inner inclined sides of the virtual second home base shape of the small leg-opening angle are each formed in a curved convex shape with a predetermined radius of curvature toward the inside of the groove, so that the small leg-opening angle decreases, and the small leg-opening angle is set to 50° to 90°; and the leg-opening angle of the large leg-opening angle portion is set to 110° to 160°.

[0014] Further, a tip reduced-diameter tapered outer surface portion is formed at the tip of the joint body; the base end of the sleeve is provided with a rounded convex inner peripheral tapered portion that can be press-contacted with the tip reduced-diameter tapered outer surface portion.

Advantages of the Invention

[0015] According to the present invention, since the tip of the inner part of the cross-sectional home base type concave groove is in a rounded shape with a predetermined radius, cracks do not occur from the tip of the inner part of the concave groove during the sleeve compression operation and under the long-term use state, and an excellent sealing state is maintained over a long period. In particular, the groove bottom wall portion at the tip of the inner part of the concave groove smoothly and deeply bites into the outer peripheral surface of the pipe, and the pipe's pull-out resistance is extremely large. Further, according to the present invention, since the concave groove is of a two-stage tapered type, when the sleeve is compressed, the groove bottom wall portion at the inner part of the concave groove accurately contracts and deforms in a direction orthogonal to the outer peripheral surface of the pipe. In other words, the diameter-reducing direction of the groove bottom wall portion at the inner part is orthogonal to the outer peripheral surface of the pipe. Moreover, the volume compressed in the orthogonal direction is sufficiently large, and the outer peripheral surface of the pipe is pressed with a high surface pressure, exhibiting excellent sealing performance.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Mode for Carrying Out the Invention

[0017] Hereinafter, the present invention will be described in detail based on the illustrated embodiments. FIG. 1 shows an embodiment of the present invention, and the upper half part above the axis line (center line) L 0 shows the state where the sleeve is not compressed, and the lower half part below the axis line L 0 shows the state where the connection is completed with the sleeve in a compressed state. Further, FIG. 2 is an enlarged view of the main part of the upper half of FIG. 1. Furthermore, FIG. 3 is an enlarged view of the main part of FIG. 2, showing the pipe P and the socket nut 3 shown in FIG. 2 omitted.

[0018] In FIGS. 1 to 3, the pipe joint according to the present invention includes a joint body 1 with a male thread 2, a socket nut 3 screwed onto the male thread 2, and a metal compression deformation sleeve 7 housed in the internal storage space 10 of the socket nut 3. The sleeve 7 has a single cross-sectional home base type concave groove 9 on the outer peripheral surface 5 near the tip. That is, in the conventional example (FIGS. 11 to 13), it had two concave grooves 59A and 59B, but this has been reduced by half.

[0019] And the sleeve 7 has a single cross-sectional rectangular seal groove 12 on the inner peripheral surface 7A at a position axially inward of the concave groove 9. A sealing material 13 such as an O-ring is installed in the seal groove 12. Regarding the radial depth dimension H of the cross-sectional rectangular seal groove 12, as shown in FIG. 2, the base end side depth dimension H 1 is smaller than the tip side depth dimension H 2 It is desirable to set it smaller.

[0020] Also, in FIG. 1, when compared with FIGS. 11, 12, and 13 of the conventional example, as is clear, the insertion cylinder part 54 inserted into the inner peripheral surface of the tip of the pipe P is omitted. And the sleeve 7 is compressively plastically deformable by the screwing in of the socket nut 3, as shown from the upper half of FIG. 1 to the lower half of FIG. 1. That is, the sleeve 7 has a single cross-sectional home base type concave groove 9 on the outer peripheral surface 5 near the tip.

[0021] As shown in FIGS. 2, 3, and 5, the inner end 9A of the concave groove 9 is formed in an arcuate shape with a predetermined radius R 1 formed. Specifically, the predetermined radius R 1 If the groove width dimension of the concave groove 9 is W 9 then 0.11·W 9 ≦R 1 ≦ 0.30·W9 Set it as follows. Also, as shown in FIGS. 3 and 5, if the opening angle (in the cross section) of the tip 9A at the inner end of the cross-sectional home-base type concave groove 9 is θ, 90° ≤ θ ≤ 120° Set it as follows.

[0022] In FIG. 6, the cases where the opening angle θ of the concave groove 9 is 90° and 120° are shown by two-dot chain lines. Further, for reference, the angularly widened home-base type concave grooves 59A and 59B in FIGS. 11 and 13 (of the conventional example) with an opening angle θ of 90° are illustrated by thin solid lines. And a more desirable opening angle θ is 100° ≤ θ ≤ 115°.

[0023] Also, as shown in FIG. 5, in the cross-sectional view of the home-base type concave groove 9, the left and right side corners 25, 25 are formed in an arc shape with a predetermined radius R 25 as follows. Moreover, this predetermined radius R 25 is set such that, if the groove width dimension of the concave groove 9 is W 9 then 0.11·W 9 ≤ R 25 ≤ 0.30·W 9 is preferably set as follows.

[0024] By the way, in FIGS. 1, 2, and 3, two annular inner peripheral shallow concave grooves 20, 20 are formed on the inner peripheral surface 7A of the sleeve 7. These shallow concave grooves 20, 20 are arranged at positions axially equidistant N 9 , N 20 , N 20 with the axial direction position L of the tip 9A at the inner end of the concave groove 9 as the center. Specifically, as shown in FIG. 3, each shallow concave groove 20 has a shallow dish shape with small rounded chamfers 21, 21 at both ends.

[0025] Incidentally, in a state where the pipe P is not inserted - in a state where the pipe is not inserted - if a compressive force F in the axial direction is applied to the sleeve 7, the sleeve 7 will plastically deform as shown in FIGS. 3 to 4(A). Regarding FIG. 4(A), if a compressive force F is applied in a state where the pipe is not inserted, the inner peripheral surface 7A of the sleeve 7 will plastically deform radially inward near the tip 9A of the original concave groove 9 to form a pipe biting projection 22. That is, if the normal pipe P is inserted, this projection 22 will deeply bite into the outer peripheral surface of the pipe P to achieve a pipe retaining state.

[0026] Incidentally, when FIG. 4(A) is viewed upside down, the biting projection 22 has a mountain shape as shown in FIG. 4(B). That is, the longitudinal cross-sectional shape of the pipe biting projection 22 is of the Mount Fuji type with a wide horizontal plane 15 obtained by horizontally cutting off the peak (in the virtual compressed state where the pipe is not inserted). Moreover, the left and right middle slopes 16, 16 of this Mount Fuji type have low sub-peaks 17, and valleys 18 are formed by these low sub-peaks 17. In short, convex and concave portions composed of sub-peaks (mountain parts) and valleys are formed in the middle slopes 16, 16. In the pipe inserted state (not shown), when an external force in the pulling direction acts on the pipe P, the corner portions 19 at the ends of the wide horizontal plane 15 at the top, the valleys 18, and the tops 17T of the low sub-peaks form small irregularities on the outer peripheral surface of the pipe P and exhibit a large pull-out resistance (resistance).

[0027] Incidentally, the cross-sectional shape of the cross-sectional home base type concave groove 9 is not limited to being symmetric left and right, and in some cases, it may be asymmetric left and right. For example, in FIGS. 3 and 5, W L >W R It may be asymmetric left and right.

[0028] In FIGS. 1 to 3, a compressive force F acts on the concave groove 9 from the right side. In other words, a compressive force F is applied from the tip surface 7T of the sleeve 7, and since the concave groove 9 deforms from the side closer to the tip surface 7T, W L >W RAs shown, it is possible to plastically deform smoothly with left - right asymmetry and strongly embed the protruding portion 22.

[0029] In addition, as shown in FIGS. 2, 3, and 4, the tip surface 7T of the sleeve 7 is inclined. That is, with respect to the virtual orthogonal plane Px orthogonal to the axis L 0 the tip surface 7T is formed in an inclined shape with a predetermined gradient angle α so that the direction of the compressive force F applied from the nut 3 is directed toward the tip end 9A at the inner part of the concave groove 9 or the groove bottom wall portion 28. That is, the concave groove 9 itself deforms in a narrowing direction with little resistance to the force F, but the part of the groove bottom wall portion 28 resists the force F.

[0030] Next, FIGS. 7 and 8 show another embodiment of the present invention. That is, the cross - sectional home - base - type concave groove 9 (shown in FIG. 7) has a virtual first home - base shape 31 with a large opening angle θ 1 and a virtual second home - base shape 32 with a small opening angle θ 2 as shown in FIG. 8(B), and is a cross - sectional shape obtained by overlapping them.

[0031] And, as shown in FIGS. 8(A) and (B), the virtual first home - base shape 31 and the virtual second home - base shape 32 have the same groove width dimension W 9 and are overlapped so that the tip end 9A at the inner part of the virtual first home - base shape 31 with the large opening angle θ 1 is deeper than the tip end 9A at the inner part of the virtual second home - base shape 32 with the small opening angle θ 1 to form a cross - sectional shape (as shown in FIG. 7). 2 The tip end 9A of the virtual second home - base shape 32 2 is formed in an arc shape with a predetermined radius R The relationship between this radius R 2 and the groove width dimension W 2 is 2 0.11·W 9 ≦R 0.11·W 9 ≦R 2 ≦0.30·W 9 It is desirable to set it as follows.

[0032] Also, in the cross-sectional shape shown in Fig. 7 (where Fig. 8(A) and Fig. 8(B) are superimposed), on each of the left and right side corners 25 of the concave groove 9, in order for the sleeve 7 to receive an axial compressive force and reduce the compressive resistance during compressive plastic deformation, side small concave depressions 33 are formed. This side small concave depression 33 is approximately three-month-shaped as shown by a number of dots in Fig. 7, and is formed by the side corner 25 shown in Fig. 8(A) (in the superposition of Fig. 8(A) and Fig. 8(B) as in Fig. 7). As shown in Fig. 8(A)(B), the depth dimension H 34 of the side straight portion 34 of the virtual first home base shape 31 35 and the depth dimension H 34 of the side straight portion 35 of the virtual second home base shape 32 35 are set to be the same as H

[0033] Regarding Fig. 7, if it is described in other expressions, it is as follows. That is, the cross-sectional shape of the concave groove 9 with Fig. 8(A) and Fig. 8(B) superimposed can be said to be a "two-stage tapered type". That is, the inner inclined sides 33A, 33A of the left and right side small concave depressions 33, 33 are tapered with a large opening angle θ 1 as shown in Fig. 7, and the back inclined sides 36, 36 are tapered with an opening angle θ 1 smaller than the above angle θ 2 Therefore, the cross-sectional shape of the concave groove 9 is a two-stage tapered type.

[0034] Furthermore, in another expression, the cross-sectional shape of the superimposed concave groove 9 has a large opening angle portion 41 and a small opening angle portion 42. That is, the large opening angle θ of the aforementioned virtual first home base shape 311 The part that forms - that is, the part formed by the inner inclined sides 33A, 33A - corresponds to the large leg-opening angle part 41. Also, the small leg-opening angle θ of the virtual second home base shape 32 2 The part that forms - that is, the part formed by the back inclined sides 36, 36 - corresponds to the small leg-opening angle part 42 (see Fig. 7).

[0035] The leg-opening angle θ of the above-mentioned large leg-opening angle part 41 1 is set to 120° to 160°. Also, the leg-opening angle θ of the above-mentioned small leg-opening angle part 42 2 is set to 80° to 100°. That is, in Figs. 7 and 8, 120° ≤ θ 1 ≤ 160°, and 80° ≤ θ 2 ≤ 100° is desirable.

[0036] Next, Figs. 9 and 10 show still another embodiment of the present invention. That is, the cross-sectional home base type concave groove 9 (shown in Fig. 9) has a virtual first home base shape 31 with a large leg-opening angle θ as shown in Fig. 10(A) 1 and a virtual second home base shape 32 with a small leg-opening angle θ shown in Fig. 10(B) 2 superimposed cross-sectional shape. And, as shown in Figs. 10(A) and (B), the above-mentioned virtual first home base shape 31 and virtual second home base shape 32 are set to have the same groove width dimension W 9 while the back end 9A of the virtual first home base shape 31 with the large leg-opening angle θ 1 is made to penetrate deeper than the back end 9A of the virtual second home base shape 32 with the small leg-opening angle θ 1 to form a superimposed cross-sectional shape (as shown in Fig. 9). 2 2 2 Moreover, the back end 9A of the virtual second home base shape 32

[0037] is formed in an arc shape with a predetermined radius R 2 The relationship between this radius R 2 and the groove width dimension W 2 is 9 ​ 0.15·W 9 ≤R 2 ≤0.30·W 9 Set as follows.

[0038] Also, in the cross-sectional shape shown in Fig. 9 (with Fig. 10(A) and Fig. 10(B) superimposed), on each of the left and right side corners 25 of the concave groove 9, in order for the sleeve 7 to receive the axial compressive force and reduce the compressive resistance during compressive plastic deformation, side small concave depressions 33 are formed. This side small concave depression 33 is approximately three-month-shaped as shown by a number of points in Fig. 7, and is formed by the side corner 25 shown in Fig. 10(A) (in the superposition of Fig. 10(A) and Fig. 10(B) as in Fig. 9). Incidentally, as shown in Fig. 10(A)(B), the depth dimension H 34 of the side straight portion 34 of the virtual first home base shape 31 35 and the depth dimension H 34 of the side straight portion 35 of the virtual second home base shape 32 35 are set to be the same as H 1 =H 1 so that in the combined state where Fig. 10(A) and Fig. 10(B) are superimposed, the approximately three-month-shaped side small concave depression 33 is formed. In other words, near the upper end of the inner inclined side 36 of the virtual second home base shape 32 shown in Fig. 10(B), the approximately three-month-shaped side small concave depression 33 is formed.

[0039] Regarding Figs. 9 and 10, if explained in other expressions, it will be as follows. That is, the cross-sectional shape of the concave groove 9 with Fig. 10(A) and Fig. 10(B) superimposed can be said to be a "two-stage taper type". That is, the inner inclined sides 33A, 33A of the left and right side small concave depressions 33, 33 are tapers with a large opening angle θ 1 as shown in Fig. 9, and the inner inclined sides 36, 36 are tapers with an opening angle θ 1 smaller than the above angle θ 2 That is, the cross-sectional shape of the concave groove 9 is a two-stage taper type.

[0040] Furthermore, (in other words,) the cross-sectional shape of the overlapping concave grooves 9 has a large leg-opening angle portion 41 and a small leg-opening angle portion 42 (see Fig. 9). That is, the large leg-opening angle θ of the aforementioned virtual first home base shape 31 1 The portion that forms it - that is, the portion formed by the inner inclined sides 33A, 33A - corresponds to the large leg-opening angle portion 41. Also, the small leg-opening angle θ of the virtual second home base shape 32 2 The portion that forms it - that is, the portion formed by the rear inclined sides 36, 36 - corresponds to the small leg-opening angle portion 42 (see Fig. 9).

[0041] The leg-opening angle θ of the large leg-opening angle portion 41 1 is set to 110° to 160°. Also, the leg-opening angle θ of the small leg-opening angle portion 42 2 is set to 50° to 90°. That is, in Figs. 9 and 10, 110° ≤ θ 1 ≤ 160°, and 50° ≤ θ 2 ≤ 90° is desirable.

[0042] By the way, in the embodiments shown in Figs. 9 and 10(B), the rear inclined sides 36, 36 each have a predetermined radius of curvature R 10 and are formed in a curved convex shape. Originally, as shown by the dotted line 38 in Fig. 9, the rear inclined side 36, which should be a straight line, is formed in a curved convex shape inward of the groove in this way. In this way, the small leg-opening angle θ of the virtual second home base shape 32 2 can be set small enough, the groove bottom thickness portion 28 can be smoothly reduced in diameter and deformed, and the groove bottom thickness portion 28 can be pressed into the outer peripheral surface of the pipe P with high precision from the orthogonal direction. Furthermore, the volume of the initial reduced diameter portion - that is, the groove bottom thickness portions 28, 28 for sleeve deformation - becomes large enough as shown in Fig. 9, and a sufficiently strong crimp connection completed state (not shown) can be obtained with respect to the outer peripheral surface of the pipe P.

[0043] As described in detail above, the present invention includes a joint body 1 with a male screw 2, a nut 3 screwed onto the male screw 2 of the joint body 1, and a sleeve 7 housed in the internal storage space 10 of the nut 3 and capable of being compression plastically deformed by the screwing-in of the nut 3; the sleeve 7 has a cross-sectional home base type concave groove 9 on the outer peripheral surface 5 near the tip; the tip end 9A of the inner part of the cross-sectional home base type concave groove 9 is formed in a circular arc shape with a predetermined radius R 1 Since the tip end 9A is formed in a circular arc shape, cracks due to stress concentration do not occur during the compression plastic deformation. As a result, a strong pipe pull-out resistance can be exerted, and external leakage of fluid can be reliably prevented over a long service period.

[0044] Further, in the present invention, since the opening angle θ in the cross-section of the tip end 9A of the cross-sectional home base type concave groove 9 is set to be sufficiently large at 90° ≤ θ ≤ 120°, compared with the conventional θ = 90° (see FIGS. 11 and 13), it bulges and deforms extremely smoothly radially inward, and can bite smoothly and firmly into the outer peripheral surface of the pipe P, exerting a strong pipe pull-out resistance. In the case where θ < 90°, the groove bottom portions 28, 28 for sleeve deformation between the inner bottom surface 9B of the concave groove 9 and the inner peripheral surface 7A of the sleeve (when an axial compressive force acts on the sleeve 7) have an excessively small radial inward component force (vector), and the protruding amount radially inward suddenly decreases. Also, in the case where θ > 120°, the protruding amount of the groove bottom portions 28, 28 for sleeve deformation (when an axial compressive force acts on the sleeve 7) radially inward suddenly decreases. The reason is that when θ > 120°, the "cross-sectional area" of the groove bottom portions 28, 28 for sleeve deformation suddenly decreases. Thus, it is important to set 90° ≤ θ ≤ 120°. Furthermore, the inventor has confirmed through many trial productions and experiments that it is particularly desirable to set 100° ≤ θ ≤ 115°.

[0045] In addition, for the pipe joint according to the present invention, the predetermined radius R at the tip end 9A of the inner part of the cross-sectional home base type concave groove 9 1 is set such that if the groove width dimension of the concave groove 9 is W 9 then 0.11·W 9 ≦R 1 ≦0.30·W 9 As a result, the problem of crack generation from the corner 60 in the conventional FIGS. 11 to 13 can be solved. That is, when the bag nut 3 is screwed into the joint body 1, it is possible to prevent cracks from occurring from the tip end 9A of the inner part of the concave groove 9 due to stress concentration, or to prevent fatigue fracture due to stress concentration from occurring after a long period under the state where the connection to the pipe P is completed. Moreover, during the tightening operation of the bag nut 3, the groove bottom part 28 for sleeve deformation bends smoothly while forming the biting projection 22, and bites sufficiently deeply into the outer peripheral surface of the pipe P without difficulty. Note that when R 1 <0.11·W 9 there is a possibility of crack generation due to stress concentration such as the conventional angular home base type concave grooves 59A and 59B. Conversely, when R 1 >0.30·W 9 the curvature radius becomes unnecessarily large, making it difficult for the groove bottom parts 28, 28 for sleeve deformation to deform during compression, or making the biting into the outer peripheral surface of the pipe insufficient.

[0046] In addition, in the present invention, only a single concave groove 9 is formed in the sleeve 7; further, the sleeve 7 has a sealing groove 12 with a rectangular cross-section on the inner peripheral surface 7A at an axially inner position than the concave groove 9, and an elastic sealing material 13 is installed in the sealing groove 12. Therefore, with respect to the connection and holding of the pipe P, it is performed by the compressive plastic deformation of the home base type concave groove 9, and with respect to the sealing of the fluid, it is performed by the elastic sealing material 13 in the sealing groove 12, so that each role and each function can be fully exerted. In addition, since the inner insertion cylinder part 54 inserted into the inner peripheral surface of the tip of the inserted pipe P is omitted, the manufacture of the pipe joint becomes easy, and the manufacturing man-hours and manufacturing costs can be significantly reduced.

[0047] In addition, the cross-sectional shape of the home plate-shaped groove 9 is such that the deepest point Z 9 A left-right dividing imaginary line L passing through 9 Based on the reference, the dimension W to the inner side edge 26 on the base end 7B side of the sleeve 7 L and the dimension W to the outer side edge 27 of the tip side of the sleeve 7 R By making the two different and asymmetrical, the following effect is obtained. That is, as shown in FIG. 3 or FIG. 5, R <W L By forming the recessed groove 9 asymmetrically with different left and right width dimensions as shown, the groove bottom portions 28, 28 can bite into the outer circumferential surface of the pipe P evenly and smoothly.

[0048] It is not easy to explain the technical reasons for this, but we will explain them based on the results of experiments. That is, W L =W R It has been found that when the groove 9 is symmetrical, the portion 29 on the base end side (left side) of the groove 9 tends to move radially inward more than the portion 30 on the tip end side (right side). So, W R <W L By making the left and right width dimensions different and asymmetrical as above, the portion 30 on the tip side (right side) can be easily moved inward, and the inward movement of both the left and right portions 29, 30 can be equalized as a whole. Therefore, the groove bottom portions 28, 28 bite into the outer circumferential surface of the pipe P evenly and smoothly.

[0049] In addition, the present invention provides a method for manufacturing a sleeve having an inner peripheral surface 7A of the sleeve 7, the inner peripheral surface 7A of the sleeve 7 being provided with an axial position L 9 Therefore, when the pipe P is inserted and an axial compressive force is applied to the sleeve 7, the sleeve 7 undergoes compressive deformation smoothly and quickly with a light force F due to the exquisite arrangement of the groove 9 (on the outer periphery of the pipe) and the shallow grooves 20 (on the inner periphery of the pipe), as shown in Figures 3 to 4(A). Moreover, the biting protrusions 22 are reliably formed and bite into the outer periphery of the pipe P, completing a strong piping connection.

[0050] Also, in the state where the pipe is not inserted, the longitudinal cross-sectional shape of the pipe biting projection 22 formed by applying an axial compressive force to plastically deform the sleeve 7 is a Mount Fuji type with a wide horizontal plane 15 obtained by horizontally cutting and removing the peak top. Moreover, the left and right middle bellies 16, 16 of the Mount Fuji type are shaped with low secondary peaks 17 forming valleys 18. Therefore, in the pipe insertion state (i.e., during normal pipe connection work), the wide horizontal plane 15 with a Mount Fuji cross-section surely bites deeply into the outer peripheral surface of the pipe and fully exerts a strong pipe gripping force. Furthermore, when a pulling force acts on the pipe P, the corner portions at the ends of the wide horizontal plane 15 of the Mount Fuji type projection 22 exert a strong anti-pulling force. Also, the low secondary peaks 17 and valleys 18 bite into the outer peripheral surface of the pipe P, further exerting a strong anti-pulling force.

[0051] The present invention also includes a joint body 1 with a male thread 2, a nut 3 screwed onto the male thread 2 of the joint body 1, and a sleeve 7 housed in the internal storage space 10 of the nut 3 and capable of being compressed and plastically deformed by the screwing-in of the nut 3. The sleeve 7 has a cross-sectional home base type concave groove 9 on the outer peripheral surface 5 near the tip. The concave groove 9 has a cross-sectional shape formed by overlapping a virtual first home base shape 31 with a large opening angle θ 1 and a virtual second home base shape 32 with a small opening angle θ 2 . The virtual first home base shape 31 and the virtual second home base shape 32 are set to have the same groove width dimension W 9 . And the tip end 9A at the back of the virtual first home base shape 31 with the large opening angle θ 1 is deeper than the tip end 9A at the back of the virtual second home base shape 32 with the small opening angle θ 1 . 2 of the virtual second home base shape 32. 2Since it has an overlapping cross-sectional shape that penetrates deeply, when the sleeve 7 receives an axial compressive force, the groove bottom web 28 causes the diameter of the pipe P to immediately contract in the vertical direction with respect to the outer peripheral surface of the pipe P. Furthermore, the operation when the sleeve 7 is deformed by receiving a large axial compressive force can be performed with a relatively small external force. Also, when the groove bottom web 28 contracts in diameter, the operation can be performed smoothly without causing cracks. In particular, the small opening angle θ 2 at the tip 9A at the inner depth 2 first starts plastic deformation and functions as a "trigger" and "direction setter" that causes the groove bottom web 28 to move radially inward. As a result, accurate compression tightening work can be performed smoothly and quickly without causing cracks in the sleeve 7.

[0052] Also, in the above overlapping cross-sectional shape, lateral small concave portions 33 for reducing the compression resistance during compression plastic deformation are formed at the left and right side corners 25 of the concave groove 9. Therefore, the axial compression external force (tightening torque) to be applied from the outside can be small, and the workability is improved. Also, in the above overlapping cross-sectional shape, the concave groove 9 has a large opening angle portion 41 and a small opening angle portion 42. Therefore, when an axial compressive force is applied to the sleeve 7, the small opening angle portion 42 moves in the diameter-reducing direction and accurately functions as a "trigger" and "direction setter". Subsequently, the axial compression movement dimension of the large opening angle portion 41 is sufficiently large, so that the groove bottom webs 28, 28 for sleeve deformation move in the radial direction and firmly and strongly press against the outer peripheral surface of the pipe P.

[0053] Also, the opening angle θ of the large opening angle portion 41 1 is set to 110° to 160°; the opening angle θ of the small opening angle portion 42 2 is set to 80° to 100°. Therefore, the large opening angle portion 41 and the small opening angle portion 42 can each fully perform their functions. That is, when an axial compressive force is applied to the sleeve 7, the small leg-opening angle portion 42 accurately and fully exerts its function of directing the sleeve 7 in the radially inward and perpendicular direction. Subsequently, the large leg-opening angle portion 41 exerts its function of strongly crimping the inner peripheral surface 7A of the sleeve 7 against the outer peripheral surface of the pipe P by compressing the sleeve 7 sufficiently axially.

[0054] Also, for the above-mentioned small leg-opening angle θ 2 the back inclined sides 36, 36 of the virtual second home base shape 32 are each formed in a curved convex shape with a predetermined radius of curvature R 10 towards the inside of the groove, so that the above-mentioned small leg-opening angle θ 2 decreases, and the small leg-opening angle θ 2 is set to 50° to 90°; and since the leg-opening angle θ 1 of the large leg-opening angle portion 41 is set to 110° to 160°, the small leg-opening angle θ 2 can be made sufficiently small, so that the tip 9A at the back 2 contracts in diameter in the radially perpendicular direction with high precision. That is, the function of the initial direction (trigger) for the groove bottom wall portion 28 to accurately contract in diameter in the radially inward direction can be exerted. On the other hand, since the large leg-opening angle portion 41 can maintain a sufficiently large leg-opening angle θ 1 , the inner peripheral surface 7A of the sleeve 7 can be strongly pressed against the outer peripheral surface of the pipe P by subsequent compression of the sleeve.

[0055] In addition, in the present invention, a tip diameter-reducing tapered outer surface portion 1T is formed at the tip of the joint body 1; the base end 7B of the sleeve 7 is provided with a rounded convex inner peripheral tapered portion 11 that can be pressed against the tip diameter-reducing tapered outer surface portion 1T, so that the inner peripheral tapered portion 11 is always pressed against the tapered outer surface portion 1T with a stable and strong surface pressure.

Explanation of Reference Numerals

[0056] 1 Joint body 2 Male screw 3 Cap nut 5 Outer peripheral surface 7 Sleeve 7A Inner peripheral surface 7B Base end 9 Concave groove 9A Tip of the recess 9A 1 Tip of the recess 9A 2 Tip of the recess 10 Internal storage space 12 Seal groove 13 Sealing material 15 Wide horizontal plane 16 Middle belly 17 Low secondary peak 18 Valley part 20 Shallow concave groove 22 Protrusion for biting-in 25 Side corner 26 Inner side 27 Outer side 31 Virtual first home base shape 32 Virtual second home base shape 33 Small side concave depression 36 Rear inclined side 41 Large leg-opening angle part 42 Small leg-opening angle part 54 Insertion cylinder part L 9 Left - right division virtual line (axial direction position) N 20 Equidistant P Pipe R 1 Predetermined radius R 10 Radius of curvature W 9 Groove width dimension W L Step W R Dimension Z 9 Deepest point θ Leg - opening angle θ 1 (Large) leg - opening angle θ 2 (Small) leg - opening angle

Claims

1. A joint body (1) with a male screw (2), a nut (3) screwed onto the male screw (2) of the joint body (1), and a sleeve (7) housed in the internal storage space (10) of the nut (3) and capable of being plastically deformed by compression by the screwing-in of the nut (3). The sleeve (7) has a cross-sectional home-base type concave groove (9) on the outer peripheral surface (5) near the tip. The tip (9A) at the back of the above cross-sectional home base type concave groove (9) is formed in a rounded shape with a predetermined radius (R 1 ), which is a feature of the pipe joint.

2. The pipe joint according to Claim 1, wherein the opening angle (θ) in the cross-section of the tip end (9A) of the inner part of the cross-sectional home-base type concave groove (9) is set as in the following formula (1). 90° ≦ θ ≦ 120°... Formula (1)

3. The pipe joint according to Claim 1, wherein the opening angle (θ) in the cross-section of the tip end (9A) of the inner part of the cross-sectional home-base type concave groove (9) is set as in the following formula (2). 100° ≦ θ ≦ 115°... Formula (2)

4. The above-mentioned predetermined radius (R 1 ) at the inner tip (9A) of the above-mentioned cross-sectional home-base type concave groove (9) is such that if the groove width dimension of the above-mentioned concave groove (9) is (W 9 ), the pipe joint according to claim 1, which is set as in the following mathematical formula 3. 0.11 · W 9 ≤ R 1 ≤ 0.30 · W 9 ・・・ Equation (3)

5. Only a single concave groove (9) is formed in the sleeve (7). Furthermore, the sleeve (7) has a cross-sectional rectangular seal groove (12) on the inner peripheral surface (7A) at a position axially inward of the concave groove (9), and an elastic sealing material (13) is installed in the seal groove (12). The pipe joint according to Claim 1, 2, 3 or 4.

6. The pipe joint according to Claim 1, 2, 3 or 4, wherein an inner insertion cylinder part (54) inserted into the inner peripheral surface of the tip of the pipe (P) to be inserted is omitted.

7. The cross-sectional shape of the cross-sectional home base type concave groove (9) is such that the deepest point (Z 9 ) of the tip of the inner part (9A) passes through the left-right division virtual line (L 9 ), and based on this The dimension (W) to the inner side edge (26) on the proximal end (7B) side of the sleeve (7) Ｌ ), and the dimension (W) to the outer side edge (27) on the distal end side of the sleeve (7) Ｒ ), are made different, and the pipe joint according to claim 1, 2, 3 or 4, which is asymmetric left and right.

8. A joint body (1) with a male screw (2), a nut (3) screwed onto the male screw (2) of the joint body (1), and a sleeve (7) housed in the internal storage space (10) of the nut (3) and capable of being plastically deformed by compression by the screwing-in of the nut (3). The sleeve (7) has a cross-sectional home-base type concave groove (9) on the outer peripheral surface (5) near the tip. On the inner peripheral surface (7A) of the above-mentioned sleeve (7), two annular inner peripheral shallow concave grooves (20)(20) are formed axially inward and axially outward from the axial direction position (L 9 ) of the tip (9A) of the above-mentioned recessed groove (9) at the back of the above-mentioned recessed groove. A pipe joint characterized by this.

9. In a state where no pipe is inserted, the longitudinal cross-sectional shape of the pipe biting projection (22) formed by plastically deforming the sleeve (7) by applying an axial compressive force is a Mount Fuji type with a wide horizontal plane (15) obtained by horizontally cutting off the peak, and moreover, the left and right middle bellies (16)(16) of the Mount Fuji type have a shape with low secondary peaks (17) forming valleys (18). The pipe joint according to Claim 8.

10. A joint body (1) with a male screw (2), a nut (3) screwed onto the male screw (2) of the joint body (1), and a sleeve (7) housed in an internal storage space (10) of the nut (3) and capable of being compressed and plastically deformed by the screwing-in of the nut (3). The sleeve (7) has a cross-sectional home-base type concave groove (9) on the outer peripheral surface (5) near the tip. The concave groove (9) has a cross-sectional shape in which a virtual first home base shape (31) with a large foot-opening angle (θ 1 ) and a virtual second home base shape (32) with a small foot-opening angle (θ 2 ) are superimposed. The above virtual first home base shape (31) and the virtual second home base shape (32) have the same groove width dimension (W 9 ), and the tip end (9A 1 ) of the inner part of the virtual first home base shape (31) with a large leg opening angle (θ 1 ) is deeper than the tip end (9A 2 ) of the inner part of the virtual second home base shape (32) with a small leg opening angle (θ 2 ) so as to penetrate deeply, and they are in a superposed cross-sectional shape A pipe joint characterized by this.

11. The pipe joint according to claim 10, wherein in the overlapping cross-sectional shape, lateral small concave portions (33) for reducing the compression resistance during compression plastic deformation are formed at the left and right lateral corner portions (25) of the concave groove (9).

12. The pipe joint according to claim 10, wherein in the overlapping cross-sectional shape, the concave groove (9) has a large opening angle portion (41) and a small opening angle portion (42).

13. The opening angle (θ 1 ) of the above-mentioned wide-opening angle portion (41) is set to 110° to 160°, The opening angle (θ 2 ) of the above-mentioned small opening angle part (42) is set to 80° to 100° The pipe joint according to claim 12.

14. The above-mentioned small opening angle (θ 2 ) of the rear inclined sides (36)(36) of the virtual second home base shape (32) are each formed in a curved convex shape inward of the groove with a predetermined radius of curvature (R 10 ), and as the above-mentioned small opening angle (θ 2 ) decreases, the small opening angle (θ 2 ) is set to 50° to 90°, and the opening angle (θ 1 ) of the above-mentioned wide-opening angle part (41) is set to 110° to 160° The pipe joint according to claim 12.

15. A tip reduced-diameter tapered outer surface portion (1T) is formed at the tip of the joint body (1). The base end (7B) of the sleeve (7) is provided with a rounded convex inner peripheral tapered portion (11) that can be pressure-contact with the tip reduced-diameter tapered outer surface portion (1T). The pipe joint according to claim 1, 8 or 10.

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