Pipe fittings

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] This invention relates to pipe fittings. [Background technology]

[0002] The pipe joint structure shown in Figures 11 to 13 was previously proposed by one of the inventors and is patented (see Patent Document 1). In particular, for use in refrigerant piping, it offers excellent ease of connection and reliably prevents external leakage of refrigerant gas, making it highly regarded and widely used in the industry. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 5736499 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, the conventional pipe fittings shown in Figures 11 to 13 have the following problems. In other words, the outer grooves 59A and 59B of the sleeve 62 were shaped like a baseball home plate, with each corner being (sharply) angular. In particular, the corners 60 at the deepest ends of the grooves 59A and 59B were sharp (see Figure 13). Therefore, if the cap nut 40 is screwed in from the state shown in Figures 11 and 13, the pipe connection will be completed as shown in Figure 12. However, cracks may occur from the original sharp corners 60. In particular, there was a risk of fatigue-induced cracks occurring after prolonged use. Also, due to its angular home plate shape, the plastic deformation operation when the material near the corners 60 of each groove 59A and 59B bites into the outer surface of the pipe P was somewhat lacking in smoothness.

[0005] Therefore, the present invention aims to solve these problems and prevent cracks from occurring in the deepest part of the sleeve groove during sleeve compression operation or after a long period of use (after connection is complete). Furthermore, it aims to provide a pipe joint in which the groove smoothly undergoes plastic deformation and bites deeply and reliably into the outer surface of the pipe, thereby exhibiting high pull-out resistance. [Means for solving the problem]

[0006] The present invention comprises a joint body with a male thread, a cap nut screwed onto the male thread of the joint body, and a sleeve housed in the internal storage space of the cap nut and capable of compression and plastic deformation by the screwing of the cap nut; the sleeve has a home plate-shaped groove in cross-section on its outer circumferential surface near its tip, and the innermost tip of the home plate-shaped groove is formed in a rounded shape with a predetermined radius.

[0007] Furthermore, the leg angle in the cross-section of the innermost tip of the home plate-shaped groove described above is set to 90°≦θ≦120°. Alternatively, the leg angle in the cross-section of the innermost tip of the home plate-shaped groove described above is set to such that 100°≦θ≦115°. Furthermore, the predetermined radius R1 at the tip of the innermost part of the home plate-shaped groove is set such that 0.11·W9≦R1≦0.30·W9, where W9 is the groove width dimension of the groove.

[0008] Furthermore, the sleeve has only one groove formed thereon, and the sleeve also has a rectangular cross-section sealing groove on its inner circumferential surface at a position axially inward from the groove, and an elastic sealing material is housed in the sealing groove. Furthermore, the internal insert portion, which is fitted into the inner circumferential surface of the tip of the inserted pipe, has been omitted.

[0009] Furthermore, the cross-sectional shape of the home plate-shaped groove is made asymmetrical by differentiating the dimensions from the inner edge on the base side of the sleeve to the outer edge on the tip side of the sleeve, based on a hypothetical line dividing the left and right sides that passes through the deepest point of the innermost tip.

[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 housed in the internal storage space of the nut and capable of being plastically deformed by compression due to the screwing of the nut; the sleeve has a cross-sectional home-base-shaped 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 of the concave groove at the inner end of the groove. Also, in the state where the pipe is not inserted, the longitudinal cross-sectional shape of the pipe biting projection formed by applying an axial compressive force to plastically deform the sleeve is a Mount Fuji type with a wide horizontal plane obtained by horizontally cutting and removing the peak; moreover, on the left and right middle bellies of the Mount Fuji type, there are 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 housed in the internal storage space of the nut and capable of being plastically deformed by compression due to the screwing of the nut; the sleeve has a cross-sectional home-base-shaped 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 of the virtual second home-base shape with a small opening angle penetrates deeper than the tip of the virtual first home-base shape with a large opening angle.

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

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

[0014] Further, a tip diameter-reduced 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-fitted against the tip diameter-reduced tapered outer surface portion.

Advantages of the Invention

[0015] According to the present invention, since the tip end 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 at the tip end of the inner part of the concave groove during the sleeve compression operation and during long-term use, and an excellent sealing state is maintained over a long period. In particular, the groove bottom wall portion at the tip end 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 reduces its diameter and deforms in a direction perpendicular 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 perpendicular to the outer peripheral surface of the pipe. Moreover, the volume compressed in the perpendicular direction is sufficiently large, and it presses the outer peripheral surface of the pipe with a high surface pressure, exhibiting excellent sealing performance.

Brief Description of the Drawings

[0016] [Figure 1] It is a cross-sectional view showing an embodiment of the present invention, with the upper half showing the intermediate state of connection with the sleeve uncompressed and the lower half showing the completed state of connection with the sleeve compressed. [Figure 2] It is an enlarged cross-sectional explanatory view of the upper half part of FIG. 1. [Figure 3] It is an enlarged cross-sectional view of the main part of FIG. 2. [Figure 4](A) is an enlarged cross-sectional view of the main part showing the compressed state from Figure 3 with the pipe not inserted, and (B) is an enlarged cross-sectional view to explain the shape of the main part of (A). [Figure 5] This is an enlarged view illustrating the shape and dimensional relationship of the groove according to the present invention. [Figure 6] This is an enlarged view illustrating the shape and dimensional relationship of the groove of the present invention in comparison with a conventional groove. [Figure 7] This is an enlarged cross-sectional view of a groove showing another embodiment of the present invention. [Figure 8] Figure 7 is an enlarged cross-sectional view used to explain the shape and structure of the groove shown in Figure 7. [Figure 9] This is an enlarged cross-sectional view of a groove showing another embodiment of the present invention. [Figure 10] Figure 9 is an enlarged cross-sectional view used to explain the shape and structure of the groove shown in Figure 9. [Figure 11] This is a cross-sectional view showing a conventional example with the cap nut not tightened. [Figure 12] This is a cross-sectional view showing a conventional example with the cap nut tightened to completion. [Figure 13] These are enlarged views of a conventional example, where (A) is an enlarged view of Figure 11 and (B) is an enlarged view of the main part of (A). [Modes for carrying out the invention]

[0017] The present invention will be described in detail below based on the illustrated embodiments. Figure 1 shows one embodiment of the present invention, where the upper half of the portion above the axial line (center line) L0 shows the uncompressed sleeve state, and the lower half of the portion below the axial line L0 shows the compressed sleeve state, indicating that the connection is complete. Furthermore, Figure 2 is an enlarged view of the main part of the upper half of Figure 1. In addition, Figure 3 is an enlarged view of the main part of Figure 2, but the pipe P and cap nut 3 shown in Figure 2 are omitted.

[0018] In Figures 1 to 3, the pipe fitting according to the present invention comprises a fitting body 1 with a male thread 2, a cap nut 3 that is screwed onto the male thread 2, and a metal compression-deformable sleeve 7 housed in the internal storage space 10 of the cap nut 3. The sleeve 7 described above has a single home plate-shaped groove 9 on its outer peripheral surface 5 near the tip. That is, while the conventional example (Figures 11 to 13) had two grooves 59A and 59B, this has been halved.

[0019] Furthermore, the sleeve 7 has a single rectangular seal groove 12 on its inner circumferential surface 7A at a position axially inward from the groove 9. A sealing material 13, such as an O-ring, is housed in this seal groove 12. Furthermore, regarding the radial depth dimension H of the rectangular cross-section seal groove 12, it is desirable to set the tip-side depth dimension H2 to be smaller than the base-side depth dimension H1, as shown in Figure 2.

[0020] Furthermore, as is clear from comparing Figure 1 with the conventional examples in Figures 11, 12, and 13, the internal cylinder portion 54 that is inserted into the inner circumferential surface of the tip of the pipe P is omitted. Furthermore, the sleeve 7 is compressible and plastically deformable by the screwing of the cap nut 3, as shown in the lower half of Figure 1, from the upper half. Specifically, the sleeve 7 has a single home plate-shaped groove 9 on its outer circumferential surface 5 near its tip.

[0021] As shown in Figures 2, 3, and 5, the innermost tip 9A of this groove 9 is formed in a rounded shape with a predetermined radius R1. Specifically, the predetermined radius R1 is determined by the width of the groove 9, where W9 is the groove width dimension. 0.11·W9 ≤ R1 ≤ 0.30·W9 Set it like this. Furthermore, as shown in Figures 3 and 5, if the angle of opening of the innermost tip 9A of the home plate-shaped groove 9 in cross-section is θ, 90°≦θ≦120° Set it like this.

[0022] In Figure 6, the cases where the leg opening angle θ of the groove 9 is 90° and 120° are shown by dashed lines. Furthermore, for reference, the angular home plate-shaped grooves 59A and 59B with a leg opening angle θ of 90°, as shown in Figures 11 and 13 (conventional examples), are illustrated with thin solid lines. And a more desirable leg-spread angle θ is, 100° ≤ θ ≤ 115°.

[0023] Furthermore, as shown in Figure 5, in the cross-sectional view of the home plate-shaped groove 9, the left and right lateral corners 25, 25 are set to a predetermined radius R 25 It is formed in a curved shape. Moreover, this predetermined radius R 25 If the groove width dimension of groove 9 is W9, then 0.11·W9≦R 25 It's best to set it to something like ≤0.30·W9.

[0024] By the way, in Figures 1, 2, and 3, two annular shallow inner grooves 20, 20 are formed on the inner circumferential surface 7A of the sleeve 7. These shallow grooves 20, 20 are located at an equidistant distance N in the axial direction, centered on the axial position L9 of the deepest tip 9A of the groove 9. 20 ,N 20 It is located at this position. Specifically, each shallow groove 20 has a shallow dish shape with small rounded chamfers 21, 21 at both ends, as shown in Figure 3.

[0025] By the way, if a compressive force F in the axial direction is applied to the sleeve 7 in the state without inserting the pipe P, the sleeve 7 will undergo plastic deformation as shown in Figures 3 to 4(A). To explain Figure 4(A), if a compressive force F is applied while the pipe is not inserted, the inner circumferential surface 7A of the sleeve 7 will undergo plastic deformation in the radial inward direction near the deepest tip 9A of the original groove 9, forming a pipe-engaging protrusion 22. In other words, if the pipe P is inserted in the correct manner, this protrusion 22 bites deeply into the outer surface of the pipe P, preventing the pipe from coming out.

[0026] Incidentally, when the above-mentioned biting projection 22 is viewed with FIG. 4(A) inverted vertically, it exhibits a mountain shape as shown in FIG. 4(B). That is, the longitudinal cross-sectional shape of the pipe-biting projection 22 is of a Mount Fuji type having a wide horizontal plane 15 obtained by horizontally cutting and removing the peak (in the compressed state without inserting the virtual pipe). Moreover, the left and right middle slopes 16, 16 of this Mount Fuji type have low subsidiary peaks 17, and valleys 18 are formed by these low subsidiary peaks 17. In short, convex and concave portions composed of subsidiary peaks (mountain portions) and valleys are formed in the middle slopes 16, 16. In the pipe insertion state (not shown), when an external force in the pulling-out 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 subsidiary peaks form small irregularities on the outer peripheral surface of the pipe P and exhibit a large pulling-out resistance (resistance force).

[0027] Incidentally, the cross-sectional shape of the cross-sectional home base type concave groove 9 may preferably be asymmetric left and right rather than symmetric left and right. For example, in FIGS. 3 and 5, W L >W R 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, since the compressive force F is applied from the tip surface 7T of the sleeve 7 and the concave groove 9 is deformed from the side closer to the tip surface 7T, it can be smoothly plastically deformed and the projection 22 can be strongly bitten in as asymmetric left and right as W L >W R is.

[0029] As shown in FIGS. 2, 3, and 4, the tip surface 7T of the sleeve 7 is inclined. That is, the tip surface 7T is formed inclined with a predetermined gradient angle α with respect to a virtual orthogonal plane Px orthogonal to the axis L0, and it is preferable to set the direction of the compressive force F applied from the nut 3 to be directed toward the inner tip 9A of the concave groove 9 or the bottom wall portion 28 of the groove. In other words, the groove 9 itself deforms in a direction that narrows with almost no resistance to the force F, but the part that resists the force F is the groove bottom wall portion 28.

[0030] Next, Figures 7 and 8 show another embodiment of the present invention. In other words, the cross-sectional home plate-shaped groove 9 (shown in Figure 7) is a cross-sectional shape formed by superimposing a virtual first home plate shape 31 with a large leg opening angle θ1 as shown in Figure 8(A) and a virtual second home plate shape 32 with a small leg opening angle θ2 as shown in Figure 8(B).

[0031] Then, as shown in Figures 8(A) and 8(B), the virtual first home plate shape 31 and the virtual second home plate shape 32 are set to have the same groove width dimension W9, and are superimposed (as shown in Figure 7) so that the rear tip 9A2 of the virtual second home plate shape 32, which has a small leg-opening angle θ2, penetrates deeper than the rear tip 9A1 of the virtual first home plate shape 31, which has a large leg-opening angle θ1. Furthermore, the inner tip 9A2 of the virtual second home plate shape 32 is formed in a rounded shape with a predetermined radius R2. The relationship between this radius R2 and the groove width dimension W9 is: 0.11·W9 ≤ R2 ≤ 0.30·W9 It is preferable to set it up like this.

[0032] Furthermore, in the cross-sectional shape shown in Figure 7 (a superimposition of Figures 8(A) and 8(B)), small lateral recesses 33 are formed at each of the left and right lateral corners 25 of the groove 9 in order to reduce the compressive resistance force during compressive plastic deformation when the sleeve 7 receives compressive force in the axial direction. This lateral small recess 33 is roughly crescent-shaped, as shown by numerous dots in Figure 7, and is formed by the lateral corner portion 25 shown in Figure 8(A) (by superimposing Figure 8(A) and Figure 8(B) as in Figure 7). Furthermore, as shown in Figures 8(A) and (B), the depth dimension H of the lateral straight portion 34 of the virtual first home plate shape 31. 34 And the depth dimension H of the straight side portion 35 of the virtual second home plate shape 32 35 H 34 =H 35By setting them identically, when Figure 8(A) and Figure 8(B) are superimposed in a combined state, a roughly crescent-shaped lateral recess 33 is formed as shown in Figure 7. In other words, a roughly crescent-shaped lateral recess 33 is formed near the upper end of the rearward sloping edge 36 of the virtual second home plate shape 32 shown in Figure 8(B).

[0033] To explain Figure 7 in other terms, it can be said that the cross-sectional shape of the groove 9 formed by superimposing (A) and (B) in Figure 8 is a "two-stage tapered type". Specifically, the inward sloping edges 33A, 33A of the left and right lateral recesses 33, 33 have a taper with a large angle of inclination θ1 (as shown in Figure 7), while the inward sloping edges 36, 36 have a taper with a smaller angle of inclination θ2 than the angle θ1. Therefore, the cross-sectional shape of the groove 9 is a two-stage taper type.

[0034] Furthermore, to put it another way, the cross-sectional shape of the overlapping grooves 9 has a wide leg-opening angle section 41 and a narrow leg-opening angle section 42. In other words, the portion that forms the large leg-spread angle θ1 of the aforementioned virtual first home base shape 31—that is, the portion formed by the inwardly inclined sides 33A, 33A—corresponds to the large leg-spread angle portion 41. Furthermore, the portion that forms the small leg-spread angle θ2 of the virtual second home base shape 32—that is, the portion formed by the inward sloping edges 36, 36—corresponds to the small leg-spread angle portion 42 (see Figure 7).

[0035] The leg-opening angle θ1 of the large leg-opening angle section 41 is set to 120° to 160°. The leg-opening angle θ2 of the small leg-opening angle section 42 is set to 80° to 100°. That is, in Figures 7 and 8, it is desirable to have 120° ≤ θ1 ≤ 160° and 80° ≤ θ2 ≤ 100°.

[0036] Next, Figures 9 and 10 show yet another embodiment of the present invention. In other words, the cross-sectional home plate-shaped groove 9 (shown in Figure 9) is a cross-sectional shape formed by superimposing a virtual first home plate shape 31 with a large leg opening angle θ1 as shown in Figure 10(A) and a virtual second home plate shape 32 with a small leg opening angle θ2 as shown in Figure 10(B). Then, as shown in Figures 10(A) and 10(B), the virtual first home plate shape 31 and the virtual second home plate shape 32 are set to have the same groove width dimension W9, and are superimposed (as shown in Figure 9) so that the rear tip 9A2 of the virtual second home plate shape 32, which has a small leg-opening angle θ2, penetrates deeper than the rear tip 9A1 of the virtual first home plate shape 31, which has a large leg-opening angle θ1.

[0037] Furthermore, the inner tip 9A2 of the virtual second home plate shape 32 is formed in a rounded shape with a predetermined radius R2. The relationship between this radius R2 and the groove width dimension W9 is: 0.15·W9 ≤ R2 ≤ 0.30·W9 Set it like this.

[0038] Furthermore, in the cross-sectional shape shown in Figure 9 (a superimposition of Figures 10(A) and 10(B)), small lateral recesses 33 are formed at each of the left and right lateral corners 25 of the groove 9 in order to reduce the compressive resistance force during compressive plastic deformation when the sleeve 7 receives compressive force in the axial direction. This lateral small recess 33 is roughly crescent-shaped, as shown by numerous dots in Figure 7, and is formed by the lateral corner portion 25 shown in Figure 10(A) (by superimposing Figures 10(A) and 10(B) as in Figure 9). Furthermore, as shown in Figures 10(A) and (B), the depth dimension H of the lateral straight portion 34 of the virtual first home plate shape 31. 34 And the depth dimension H of the straight side portion 35 of the virtual second home plate shape 32 35 H 34 =H 35 By setting them identically, a roughly crescent-shaped lateral recess 33 is formed in the combined state where Figure 10(A) and Figure 10(B) are superimposed. In other words, a roughly crescent-shaped lateral recess 33 is formed near the upper end of the rearward sloping edge 36 of the virtual second home plate shape 32 shown in Figure 10(B).

[0039] To explain Figures 9 and 10 in other terms, it can be said that the cross-sectional shape of the groove 9 formed by superimposing (A) and (B) in Figure 10 is a "two-stage tapered type". Specifically, the inward sloping edges 33A, 33A of the left and right lateral recesses 33, 33 have a taper with a large angle of inclination θ1 (as shown in Figure 9), while the inward sloping edges 36, 36 have a taper with a smaller angle of inclination θ2 than the angle θ1. Therefore, the cross-sectional shape of the groove 9 is a two-stage taper type.

[0040] Furthermore, (to put it another way,) the cross-sectional shape of the overlapping grooves 9 has a wide leg-opening angle section 41 and a narrow leg-opening angle section 42 (see Figure 9). In other words, the portion that forms the large leg-spread angle θ1 of the aforementioned virtual first home base shape 31—that is, the portion formed by the inwardly inclined sides 33A, 33A—corresponds to the large leg-spread angle portion 41. Furthermore, the portion that forms the small leg-spread angle θ2 of the virtual second home base shape 32—that is, the portion formed by the inward sloping edges 36, 36—corresponds to the small leg-spread angle portion 42 (see Figure 9).

[0041] The leg-opening angle θ1 of the large leg-opening angle section 41 is set to 110° to 160°. The leg-opening angle θ2 of the small leg-opening angle section 42 is set to 50° to 90°. That is, in Figures 9 and 10, 110° ≤ It is desirable to set θ1 ≤ 160° and 50° ≤ θ2 ≤ 90°.

[0042] By the way, in the embodiments shown in Figures 9 and 10(B), the inclined sides 36, 36 each have a predetermined radius of curvature R 10 It is formed in a curved convex shape. Originally, as shown by the dotted line 38 in Figure 9, the inward sloping side 36 should be a straight line, but it is formed in this way as a curved convex shape toward the groove. In this way, the small leg opening angle θ2 of the virtual second home base shape 32 can be set to a sufficiently small size, the groove bottom wall portion 28 can be smoothly deformed to reduce its diameter, and the groove bottom wall portion 28 can be pressed against the outer surface of the pipe P with high precision from a direction perpendicular to it. Furthermore, the volume of the initial diameter reduction portion -- that is, the groove bottom wall portions 28, 28 for sleeve deformation -- becomes sufficiently large as shown in Figure 9, and a sufficiently strong crimped connection state (not shown) is obtained with respect to the outer surface of the pipe P.

[0043] As described in detail above, the present invention comprises a joint body 1 with a male thread 2, a cap nut 3 that is screwed onto the male thread 2 of the joint body 1, and a sleeve 7 housed in the internal storage space 10 of the cap nut 3 and capable of compression and plastic deformation by the screwing of the cap nut 3; the sleeve 7 has a home plate-shaped groove 9 on its outer circumferential surface 5 near its tip; and the innermost tip 9A of the home plate-shaped groove 9 is formed in a rounded shape with a predetermined radius R1. Because the innermost tip 9A is rounded, cracks due to stress concentration are prevented during the compression and plastic deformation. This enables the pipe to exhibit strong pull-out resistance and reliably prevents external leakage of fluid over a long period of use.

[0044] Furthermore, in this invention, the leg opening angle θ in the cross-section of the innermost tip 9A of the home plate-shaped groove 9 is set to a sufficiently large value of 90°≦θ≦120°. Compared to the conventional θ=90° (see Figures 11 and 13), it undergoes extremely smooth radial inward bulging deformation, allowing it to smoothly and firmly bite into the outer surface of the pipe P, thereby exhibiting strong resistance to pipe pull-out. Furthermore, when θ < 90°, the bottom wall portion 28, 28 of the groove for sleeve deformation between the deep bottom surface 9B of the groove 9 and the inner circumferential surface 7A of the sleeve becomes too small (when an axial compressive force acts on the sleeve 7), and the amount of radial inward protrusion decreases abruptly. Furthermore, when θ > 120°, the amount of radial inward protrusion of the sleeve deformation groove bottom portion 28, 28 (when an axial compressive force is applied to the sleeve 7) decreases abruptly. This is because when θ > 120°, the "cross-sectional area" of the sleeve deformation groove bottom portion 28, 28 decreases abruptly. Thus, it is important to set 90° ≤ θ ≤ 120°. Furthermore, the inventors have confirmed through numerous prototypes and experiments that it is particularly desirable to set the angle to 100° ≤ θ ≤ 115°.

[0045] Furthermore, in the pipe joint according to the present invention, the predetermined radius R1 of the innermost tip 9A of the home plate-shaped groove 9 is set such that 0.11·W9≦R1≦0.30·W9, where W9 is the groove width dimension of the groove 9. This solves the problem of crack generation from the corner 60 as shown in Figures 11 to 13 of the conventional joint. In other words, when screwing the cap nut 3 into the joint body 1, stress concentration can be prevented from causing cracks at the deepest tip 9A of the groove 9, or from causing fatigue fracture due to stress concentration long after the connection to the pipe P is complete. Moreover, during the tightening of the cap nut 3, the bottom wall portion 28 of the sleeve deformation groove bends smoothly and forms a biting protrusion 22, allowing it to bite sufficiently deep into the outer surface of the pipe P without force. Furthermore, if R1 < 0.11·W9, there is a risk of crack formation due to stress concentration, similar to the conventional angular home plate-shaped grooves 59A and 59B. Conversely, if R1 > 0.30·W9, the radius of curvature becomes unnecessarily large, making it difficult for the bottom wall portions 28, 28 of the sleeve deformation grooves to deform under compression, and resulting in insufficient engagement with the outer surface of the pipe.

[0046] Furthermore, in the present invention, the sleeve 7 has only one groove 9 formed therein; moreover, the sleeve 7 has a rectangular cross-sectional seal groove 12 on its inner circumferential surface 7A at a position axially inward from the groove 9, and an elastic seal material 13 is installed inside the seal groove 12. Thus, the connection and holding of the pipe P is performed by the compressive plastic deformation of the home plate-shaped groove 9, and the sealing of the fluid is performed by the elastic seal material 13 inside the seal groove 12, thereby enabling each role and function to be fully performed. Furthermore, since the internal insertion cylinder portion 54, which is inserted into the inner circumferential surface of the tip of the pipe P to be inserted, is omitted, the manufacturing of the pipe joint becomes easier, and the manufacturing man-hours and production costs can be significantly reduced.

[0047] Furthermore, the cross-sectional shape of the home plate-shaped groove 9 is such that the dimension W is defined as the distance from the inner side 26 on the base end 7B side of the sleeve 7, with respect to the left-right dividing imaginary line L9 passing through the deepest point Z9 of the inner tip 9A. L And the dimension W from the outer side edge 27 at the tip of sleeve 7. R By making them different and creating asymmetry, the following effect is achieved. That is, as shown in Figure 3 or Figure 5, W R <W L By creating an asymmetrical groove 9 with different width dimensions on the left and right sides, the groove bottom sections 28, 28 can bite into the outer surface of the pipe P evenly and smoothly.

[0048] The technical reasons are not easy to explain, but I will explain them based on the results of the experiment. That is, W L =W R It has been found that when the groove 9 is symmetrical, the portion 29 on the proximal end (left side) of the groove 9 tends to move radially inward more than the portion 30 on the tip side (right side). Therefore, W R <W L As shown above, by making the left and right width dimensions different and creating an asymmetrical design, the tip side (right side) portion 30 can be moved inward more easily, and the inward movement of both left and right portions 29 and 30 can be made equal overall. Therefore, the groove bottom portions 28, 28 bite into the outer surface of the pipe P evenly and smoothly.

[0049] Furthermore, in the present invention, two annular inner circumferential shallow grooves 20, 20 are formed on the inner circumferential surface 7A of the sleeve 7, extending axially inward and axially outward from the axial position L9 of the innermost tip 9A of the groove 9. Therefore, when a pipe P is inserted and an axial compressive force is applied to the sleeve 7, the exquisite arrangement of the groove 9 (on the outer circumference of the pipe) and the shallow grooves 20, 20 (on the inner circumference of the pipe) causes the compression-deformed sleeve 7 to deform smoothly and quickly with a light force F, as shown in Figures 3 to 4(A). Moreover, the bite-in protrusions 22 are reliably formed, biting into the outer circumferential surface of the pipe P, resulting in a firm and complete pipe connection.

[0050] Furthermore, when the pipe is not inserted, the vertical cross-sectional shape of the pipe-engaging protrusion 22, which is formed by applying axial compressive force to plastically deform the sleeve 7, is shaped like Mount Fuji, with a wide horizontal surface 15 formed by horizontally cutting off the summit. Moreover, the left and right middle slopes 16, 16 of the Mount Fuji shape are equipped with low secondary peaks 17 that form valleys 18. Therefore, when the pipe is inserted (i.e., during normal pipe connection work), the wide horizontal surface 15 of the Mount Fuji cross-section bites deeply into the outer surface of the pipe, and exerts a strong pipe gripping force. Furthermore, when an uplift force is applied to the pipe P, the corners at the ends of the wide horizontal surfaces 15 of the Mount Fuji-shaped protrusions 22 exert strong uplift resistance. In addition, the low secondary peaks 17 and valleys 18 bite into the outer surface of the pipe P, further enhancing the uplift resistance.

[0051] Furthermore, the present invention comprises a joint body 1 with a male thread 2, a cap nut 3 that is screwed onto the male thread 2 of the joint body 1, and a sleeve 7 housed in the internal storage space 10 of the cap nut 3 and capable of compression and plastic deformation by the screwing of the cap nut 3; the sleeve 7 has a home plate-shaped groove 9 on its outer circumferential surface 5 near its tip; the groove 9 has a cross-sectional shape formed by superimposing a virtual first home plate shape 31 with a large leg opening angle θ1 and a virtual second home plate shape 32 with a small leg opening angle θ2; and the above The virtual first home plate shape 31 and the virtual second home plate shape 32 are superimposed in a cross-sectional shape where the groove width dimension W9 is set to the same value, and the inner tip 9A2 of the virtual second home plate shape 32, which has a small leg opening angle θ2, penetrates deeper than the inner tip 9A1 of the virtual first home plate shape 31, which has a large leg opening angle θ1. Therefore, when the sleeve 7 is subjected to a compressive force in the axial direction, the groove bottom wall portion 28 immediately deforms to shrink in diameter in the vertical direction relative to the outer surface of the pipe P. Furthermore, the operation of the sleeve 7 when it deforms under a large compressive force in the axial direction can be performed with a relatively small external force. In addition, the groove bottom wall portion 28 can be operated smoothly without cracking when it deforms to shrink in diameter. In particular, the innermost tip 9A2 at a small leg opening angle θ2 is the first to initiate plastic deformation, acting as a "trigger" and "direction" to direct the groove bottom wall portion 28 radially inward. This allows for smooth, rapid, and accurate compression tightening without causing cracks in the sleeve 7.

[0052] Furthermore, in the superimposed cross-sectional shape described above, small lateral recesses 33 are formed at each of the left and right lateral corners 25 of the groove 9 to reduce the compressive resistance force during compressive plastic deformation. Therefore, the axial compressive force (tightening torque) that needs to be applied from the outside can be small, improving workability. Furthermore, in the superimposed cross-sectional shape described above, the groove 9 has a large leg-opening angle portion 41 and a small leg-opening angle portion 42. When an axial compressive force is applied to the sleeve 7, the small leg-opening angle portion 42 moves in the diameter-reducing direction, accurately performing a directional (triggering) function. Subsequently, the axial compressive movement dimension of the large leg-opening angle portion 41 is sufficiently large, thereby causing the sleeve deformation groove bottom portions 28, 28 to move in the radial direction and reliably and strongly press against the outer surface of the pipe P.

[0053] Furthermore, since the leg-opening angle θ1 of the large leg-opening angle section 41 is set to 110° to 160°, and the leg-opening angle θ2 of the small leg-opening angle section 42 is set to 80° to 100°, the large leg-opening angle section 41 and the small leg-opening angle section 42 can fully perform their respective functions. In other words, when an axial compressive force is applied to the sleeve 7, the small leg-opening angle portion 42 accurately and fully performs its function of directing inward in a radial vertical direction, and subsequently, the large leg-opening angle portion 41 compresses the sleeve 7 sufficiently in the axial direction, performing its function of strongly pressing it against the outer surface of the pipe P.

[0054] Furthermore, the inclined sides 36, 36 of the virtual second home base shape 32 with the small leg opening angle θ2 each have a predetermined radius of curvature R 10 As a result, the groove bottom portion 28 is formed in a curved convex shape inward, reducing the small leg opening angle θ2, which is set to 50° to 90°; and the leg opening angle θ1 of the large leg opening portion 41 is set to 110° to 160°, so the small leg opening angle θ2 can be made sufficiently small, causing the inner tip 9A2 to deform in a radially vertical direction with high precision. In other words, the groove bottom portion 28 can perform the function of initial direction setting (trigger) for accurate radial inward diameter reduction. In contrast, the wide-opening angle section 41 can maintain a sufficiently large opening angle θ1, so that the inner surface 7A of the sleeve 7 can be strongly pressed against the outer surface of the pipe P by subsequent sleeve compression.

[0055] Furthermore, in the present invention, the tip of the joint body 1 has a tapered outer surface portion 1T with a reduced diameter tip; and the base end 7B of the sleeve 7 is provided with a rounded convex inner tapered portion 11 that can be pressed against the tapered outer surface portion 1T with a reduced diameter tip. Therefore, the pressing of the inner tapered portion 11 against the tapered outer surface portion 1T is always performed with stable and strong (large) surface pressure. [Explanation of Symbols]

[0056] 1. Fitting body 2 Male screws 3 cap nuts 5 Outer surface 7 sleeves 7A Inner surface 7B Proximal end 9. Grooves 9A Inner tip 9A1 Rear tip 9A2 inner tip 10 Internal storage space 12 seal grooves 13. Sealant 15. Wide horizontal plane 16 Mid-slope 17 Low secondary peak 18 Tanibe 20 Shallow groove 22 Protrusion for biting 25 Side corner 26 Inner side 27 Outer side 31 Virtual First Home Plate Shape 32 Virtual Second Home Plate Shape 33 Lateral small depression 36. Sloping edge towards the back 41 Wide leg spread angle section 42 Small leg-spread angle section 54 Inner cylinder part L9 Left / Right Split Virtual Line (Axial Direction Position) N 20 equidistant P Pipe R1 predetermined radius R 10 radius of curvature W9 groove width dimension W L Inch W R size Z9 deepest point θ Leg opening angle θ1 (large) leg-spread angle θ2 (small) leg-spread angle

Claims

1. The fitting comprises a fitting body (1) with a male thread (2), a cap nut (3) that is screwed onto the male thread (2) of the fitting body (1), and a sleeve (7) housed in an internal storage space (10) of the cap nut (3) and which is compressible and plastically deformable as the cap nut (3) is screwed in. The sleeve (7) has a home plate-shaped groove (9) on its outer surface (5), The innermost tip (9A) of the above cross-sectional home plate-shaped groove (9) is formed in a rounded shape with a predetermined radius (R1). The cross-sectional shape of the home plate-shaped groove (9) is based on the left-right dividing imaginary line (L9) passing through the deepest point (Z9) of the innermost tip (9A), A pipe joint characterized by having a left-right asymmetry, where the dimension (WL) from the inner side edge (26) on the base end (7B) side of the sleeve (7) to the outer side edge (27) on the tip side of the sleeve (7) is different from the dimension (WR) from the outer side edge (27) on the tip side of the sleeve (7).

2. The pipe joint according to claim 1, wherein the leg opening angle (θ) in the cross-section of the innermost tip (9A) of the above-mentioned home plate-shaped groove (9) is set as shown in the following formula 1. 90° ≤ θ ≤ 120° ... Formula (1)

3. The pipe joint according to claim 1, wherein the leg opening angle (θ) in the cross-section of the innermost tip (9A) of the above-mentioned home plate-shaped groove (9) is set as shown in the following formula 2. 100° ≤ θ ≤ 115° ... Formula (2)

4. The pipe fitting according to claim 1, wherein the predetermined radius (R1) of the innermost tip (9A) of the above-mentioned home plate-shaped recessed groove (9) is set as shown in the following formula 3, where (W9) is the groove width dimension of the recessed groove (9). 0.11・W9 ≤ R1 ≤ 0.30・W9 ... Formula (3)

5. The sleeve (7) has only one groove (9) formed on it. Furthermore, the pipe fitting according to claim 1, 2, 3, or 4, wherein the sleeve (7) has a rectangular cross-sectional seal groove (12) on its inner circumferential surface (7A) at a position axially inward from the recessed groove (9), and an elastic seal material (13) is installed in the seal groove (12).

6. The pipe fitting according to claim 1, 2, 3, or 4, wherein the internal insertion cylinder portion (54) that is inserted into the inner circumferential surface of the tip of the pipe (P) to be inserted is omitted.

7. The pipe fitting according to claim 1, 2, 3, or 4, characterized in that two annular inner shallow grooves (20) (20) are formed on the inner circumferential surface (7A) of the sleeve (7), extending axially inward and axially outward from the axial position (L9) of the innermost tip (9A) of the cross-sectional home plate-shaped groove (9).

8. With the pipe not inserted, the longitudinal cross-sectional shape of the pipe-inserting protrusion (22) formed by applying an axial compressive force to the sleeve (7) and plastically deforming it is, It is a Mount Fuji type with a wide horizontal plane (15) formed by horizontally cutting and removing the summit. Moreover, the left and right mid-slope (16) (16) of the Mount Fuji shape have low secondary peaks (17) that form valleys (18). It has a shape that is equipped with The pipe fitting according to claim 7.

9. The above-mentioned home plate-shaped groove (9) has a cross-sectional shape formed by superimposing a virtual first home plate shape (31) with a large leg opening angle (θ1) and a virtual second home plate shape (32) with a small leg opening angle (θ2). The virtual first home plate shape (31) and the virtual second home plate shape (32) described above have the same groove width dimension (W9), and their cross-sectional shapes are superimposed such that the rear tip (9A2) of the virtual second home plate shape (32), which has a small leg-spread angle (θ2), penetrates deeper than the rear tip (9A1) of the virtual first home plate shape (31), which has a large leg-spread angle (θ1). A pipe fitting according to claim 1, 2, 3, or 4, characterized in that it is a pipe fitting according to claim 1, 2, 3, or 4.

10. In the superimposed cross-sectional shape described above, the pipe joint according to claim 9, wherein small lateral recesses (33) are formed at each left and right lateral corner (25) of the home plate-shaped recessed groove (9) in the cross-section, which reduce the compressive resistance force during compressive plastic deformation.

11. In the superimposed cross-sectional shape described above, the cross-sectional home plate-shaped groove (9) has a wide leg angle portion (41) and a narrow leg angle portion (42) as described in claim 9.

12. The leg-spread angle (θ1) of the above-mentioned wide-leg-spread section (41) is set to 110° to 160°. The leg-spread angle (θ2) of the above-mentioned small leg-spread angle section (42) is set to 80° to 100°. The pipe fitting according to claim 11.

13. The inward sloping edges (36) (36) of the virtual second home base shape (32) with the above small leg opening angle (θ2) are each formed in a curved convex shape inward of the groove with a predetermined radius of curvature (R10), thereby reducing the above small leg opening angle (θ2), and the small leg opening angle (θ2) is set to 50° to 90°. Furthermore, the leg-spread angle (θ1) of the above-mentioned wide-leg-spread section (41) is set to 110° to 160°. The pipe fitting according to claim 11.

14. A tapered outer surface portion (1T) is formed at the tip of the above-mentioned joint body (1). The base end (7B) of the sleeve (7) is provided with a rounded convex inner circumferential tapered portion (11) that can be pressed against the tip diameter-reducing tapered outer surface portion (1T). The pipe fitting according to claim 1.

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