Pipe fittings

Abstract

To provide a pipe joint that stably exerts strong anti-pipe drawing force and does not break locally.SOLUTION: A number of pipe-digging small irregularity parts 6 are formed in a region Y near an axial position L9 of a farther tip 9A of a recess groove 9 in an inner peripheral surface 7A of a sleeve 7.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] This invention relates to pipe fittings. [Background technology]

[0002] The pipe fittings with the structures shown in Figures 12 to 14 are used for refrigerant piping, offering good workability for pipe connection and reliably preventing external leakage of refrigerant gas. They have been well-received in the industry and are widely used (see Patent Document 1). [Prior art documents] [Patent Documents]

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

[0004] However, the conventional pipe fittings shown in Figures 12 to 14 had 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 14). Therefore, if the cap nut 40 is screwed in from the state shown in Figures 12 and 14, the pipe connection will be completed as shown in Figure 13. 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, 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 undergoes smooth plastic deformation while reliably biting into the outer surface of the pipe, thereby stably exhibiting a large 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 on its outer circumferential surface; the innermost tip of the groove is formed in a rounded shape with a predetermined radius; and on the inner circumferential surface of the sleeve, numerous small protrusions for pipe engagement are formed in the vicinity of the axial position of the innermost tip of the groove.

[0007] Furthermore, if the groove width dimension of the groove is W9, the inner end of the vicinity region where the small irregularities are formed is set at an axial inward position of 0.6·W9 to 1.0·W9 from the axial position of the innermost tip of the groove; and the outer end of the vicinity region is set at an axial outward position of 0.1·W9 to 0.5·W9 from the axial position of the innermost tip of the groove.

[0008] Furthermore, the small grooves for pipe engagement are provided with a parallel threaded section on the axially inward side with a constant thread groove depth and a tapered threaded section on the axially outward side where the thread groove depth gradually decreases towards the tip; the boundary position between the parallel threaded section and the tapered threaded section is set to coincide with the axial position of the tip of the innermost part of the groove, or to an axially inward position within twice the thread pitch.

[0009] Furthermore, the cross-sectional shape of the home plate-shaped groove was made asymmetrical by setting the dimension from the inner side of the base end of the sleeve to the outer side of the tip end of the sleeve to be larger than the dimension from the inner side of the base end of the sleeve to the outer side of the tip end of the sleeve, based on a left-right dividing imaginary line passing through the deepest point of the innermost tip of the back end.

[0010] Furthermore, the cross-sectional shape of the groove portion of the small protrusions for pipe insertion is arc-shaped, and the cross-sectional shape of the protrusion portion is Mount Fuji-shaped with a flat top. [Effects of the Invention]

[0011] According to the present invention, it is possible to prevent cracks from forming from the inner circumferential surface of the sleeve to the deepest tip of the groove when the sleeve is compressed and deformed. Therefore, an excellent sealing state can be maintained over a long period of time. Furthermore, numerous small protrusions for pipe engagement are formed in the vicinity of the axial position at the deepest tip of the groove. As the groove compresses, these small protrusions bite into the outer surface of the pipe, providing a stable pipe pull-out prevention force. In particular, by having numerous small protrusions bite into the outer surface of the pipe (instead of the conventional method where one or two edges bite in), the pull-out resistance is distributed, cleverly avoiding stress concentration and preventing cracks from forming in the sleeve. Moreover, the pull-out resistance of the pipe is the sum of the values ​​from the numerous protrusions biting into the pipe, and can be equivalent to or even greater than the pull-out resistance of the conventional method with one or two edges. [Brief explanation of the drawing]

[0012] [Figure 1] This cross-sectional view shows one embodiment of the present invention, with the upper half showing the intermediate connection state with the sleeve uncompressed and the lower half showing the completed connection state with the sleeve compressed. [Figure 2] This is a magnified view of the main part of the upper half of Figure 1. [Figure 3] This is a magnified cross-sectional view of the main part of the sleeve. [Figure 4] This is a magnified cross-sectional view of the main part of the sleeve, shown in a more enlarged view. [Figure 5] It is an enlarged sectional view of the main part showing the state during the construction of a sleeve capable of compression plastic deformation. [Figure 6] It is an enlarged sectional view of the main part showing the state immediately before the completion of the compression deformation of the sleeve. [Figure 7] It is an enlarged sectional view of the main part showing two specific examples of the small uneven parts for pipe biting according to the present invention. [Figure 8] It is an enlarged sectional view of the main part showing a comparative example of the sleeve. [Figure 9] It is an enlarged sectional view of the main part showing the state during the deformation of the sleeve of the comparative example while receiving a compression force. [Figure 10] It is an enlarged sectional view of the main part showing the state during further deformation of the sleeve of the comparative example from the state of FIG. 9. [Figure 11] It is an enlarged sectional view of the main part showing the state in which the sleeve of the comparative example is compressed and deformed to cause a problem from the state of FIG. 10. [Figure 12] It shows a conventional example and is a sectional view of the state where the bag nut is not tightened. [Figure 13] It shows a conventional example and is a sectional view of the state where the bag nut is tightened completely. [Figure 14] It is an enlarged view of a conventional example, (A) is an enlarged view of the main part of FIG. 12, and (B) is an enlarged view of the main part of (A).

Embodiments for Carrying Out the Invention

[0013] Hereinafter, the present invention will be described in detail based on the illustrated embodiments. [[ID= thirty-eight ]]FIG. 1 shows an embodiment of the present invention. The upper half part from the axial center line (center line) L0 shows the state of the sleeve in an uncompressed state, and the lower half part from the axial center line L0 shows the state where the connection is completed as the sleeve is in a compressed state. Further, FIG. 2 is an enlarged view of the main part of the upper half of FIG. 1, and further, FIG. 3 shows only the sleeve 7 shown in FIG. 2.

[0014] In Figures 1 to 3, the pipe joint according to 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, and a metal compression-plastic deformation 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. In other words, while conventional examples (Figures 12 to 14) had two grooves 59A and 59B, the present invention reduces this number by half (see Figure 1).

[0015] The innermost tip 9A of this groove 9 is formed in a rounded shape with a predetermined radius R1. Furthermore, L9 indicates the axial position of the innermost tip 9A of the groove 9. On the inner circumferential surface 7A of the sleeve 7, small irregularities 6 for pipe engagement are formed in the region Y near the axial position L9.

[0016] Here, we will explain the cross-sectional shape of the home plate-shaped groove 9. The dimension W of the sleeve 7 to the inner side 36 on the base end is measured from the left-right dividing imaginary line L9 that passes through the deepest point Z9 of the inner tip 9A mentioned above—which may also be referred to as the "axial direction position L9" in the description of this invention—as a reference point. L The dimension W is the outer side 37 at the tip of sleeve 7. R Set it to be larger than that. In other words, W R <W L By setting it in this way, the cross-sectional shape of the groove 9 becomes asymmetrical.

[0017] Next, the neighboring region Y will be explained in detail below. As shown in Figures 3, 4, and 7, the inner end 11 (in the axial direction) of the neighboring region Y is set to be located at an axial inward position of 0.6·W9 to 1.0·W9 from the axial position L9 of the innermost tip 9A of the groove 9. That is, in Figure 4, 0.6·W9≦L 11 The value should be ≤ 1.0·W9. (Note that W9 is the groove width dimension of groove 9.)

[0018] Furthermore, the outer end 12 (in the axial direction) of the neighboring region Y is set to be located at an axially outward position of 0.1·W9 to 0.5·W9 from the axial position L9 of the innermost tip 9A of the groove 9. That is, 0.1·W9≦L 12 Let ≤ 0.5·W9. As described above, the vicinity region Y in which the small irregularities 6 are formed is unevenly distributed in the axial direction (from the axial position L9 of the axial tip 9A of the innermost part of the groove 9).

[0019] The small protrusions 6 for pipe insertion are formed, for example, by a (pipe insertion) threaded portion 20, and consist of a parallel threaded portion 21 and a tapered threaded portion 22. In Figure 4, (L 11 The dimension range of -ΔL) is where the parallel threaded portion 21 is formed, and also (L 12 A tapered threaded portion 22 is formed within the dimension range of +ΔL.

[0020] Incidentally, the tapered thread portion 22 differs from a normal tapered thread. Specifically, the diameter of the bottom of the thread groove of the tapered thread portion 22 is tapered, gradually decreasing axially outward. However, as is clear from Figure 4 or Figure 7, the inner diameter dimension of the tapered thread portion 22 does not change in the axial direction and is set to be the same dimension as the inner circumferential surface 7A of the sleeve 7. In other words, the tapered thread portion 22 of the present invention has a gradually decreasing thread groove depth towards the tip.

[0021] The reason for providing the tapered thread section 22, in which the thread groove depth gradually decreases towards the tip, will be explained below. In other words, we want to reduce the diameter of the axial inner region first, using the axial position L9 as a reference, but for that purpose, we do not want to create grooves in the axial outer region. However, if we only create grooves in the axial inner region, the pipe pull-out resistance (pipe detachment prevention force) will be insufficient. Therefore, we are forced to create grooves in the axial outer region as well.

[0022] Therefore, a "tapered screw section 22" was provided, which gradually reduces the screw groove depth towards the tip (outward). Then, the boundary position B between the parallel thread portion 21 and the tapered thread portion 22 is set to an axially inward position with a small dimension ΔL that is no more than twice the thread pitch P, or the boundary position B is made to coincide with the axial position L9.

[0023] Incidentally, it is desirable to perform the cutting of the parallel thread portion 21 and the tapered thread portion 22 continuously. When performing this cutting, cutting is started with a cutting tool (cutting blade) from the leftmost parallel thread groove 21A shown in Figures 4 and 7(A), and the parallel thread portion 21 is cut to the boundary position B while applying radial outward feed, and then the tapered thread portion 22 is cut to the outer end 12 (while gradually retracting the cutting tool).

[0024] Furthermore, as shown in Figures 4 and 5, (preferably) the cross-sectional shape of the groove portion 20N of the small protrusions 6 for pipe engagement is arc-shaped, and the cross-sectional shape of the protrusion 20T is a Mount Fuji shape with a flat top. When a compressive force F(F') is applied to the sleeve 7, as shown in Figures 5 and 6, the groove 9 deforms under compression, and the small protrusion 20T with a Mount Fuji cross-sectional shape bites into the pipe 30. The sharp peak corners of these small protrusions 20T bite into the pipe 30, generating a stable and strong pull-out resistance for the pipe.

[0025] If a compressive force F' is applied to a roughly home plate-shaped groove 9 in a state where no external force is applied in the axial direction, as shown in Figure 5, it will be compressed in the axial direction, ultimately resulting in the state shown in Figure 6. In other words, from the midpoint 9M of the depth of the compressed groove 9 to the tip 9A at the back, it forms a plane perpendicular to the axis of the pipe 30. Moreover, the axial position of the sleeve 7 coincides with the smallest diameter point (bottom dead center) T0 of the inner circumferential surface 7A of the sleeve 7 and the tip 9A at the back.

[0026] As is clear from Figure 6, the inclined surface 15 on the axially inward side of the smallest diameter section (bottom dead center) T0 corresponds to the parallel screw section 21 (see Figure 4). On the other hand, on the axial outer side of the minimum diameter portion (bottom dead center) T0, as shown in FIGS. 4 and 6, a tapered screw portion 22 corresponds (is arranged).

[0027] In the comparative example shown in FIGS. 8 to 11, since a sharp and large edge 33 was present in the vicinity of the minimum diameter portion (bottom dead center) T0, when a large external force (compressive force) F acted, as shown in FIG. 11, a crack 34 occurred as indicated by the arrow N 34 There was a problem that it occurred as follows. In the present invention, a large number of small convex portions 20T... are made to bite into the pipe 30, and by avoiding stress concentration (for stress dispersion), the occurrence of cracks is surely prevented.

[0028] Next, the cross-sectional shape of the concave groove 9 will be described. [[ID=1》図2~図4に示した凹溝9は、次のような断面形状である。 That is, the concave groove 9 has a cross-sectional home base type, and the tip 9A at the inner part thereof has a rounded shape with a predetermined radius R1. Further, the opening angle of the tip 9A at the inner part is 90° to 120°. In addition, on each of the side corner portions 25, 25 of the home base type concave groove 9, side small concave portions 26 are formed (in a notch shape).

[0029] Incidentally, (although not shown in the figure), it may be preferable to omit the side small concave portions 26, 26 of the concave groove 9. Also, it is possible to freely deform the cross-sectional shape of the concave groove 9, such as forming the left and right gradient lines 9L, 9L leading to the tip 9A at the inner part of the concave groove 9 in a curved convex shape.

[0030] By the way, FIG. 7(B) shows another embodiment, and instead of the parallel screw portion 21 described in FIG. 7(A), a plurality of independent annular grooves 24... are arranged in parallel. That is, the independent annular grooves 24... are in a plane perpendicular to the axis and are arranged independently at a predetermined pitch. Incidentally, even in FIG. 7(B), similar to FIG. 7(A), the tapered screw portion 22 is continuously provided.

[0031] 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; the innermost tip 9A of the groove 9 is formed in a rounded shape with a predetermined radius R1; and on the inner circumferential surface 7A of the sleeve 7, numerous small protrusions 6 for pipe engagement are formed in the vicinity Y of the axial position L9 of the innermost tip 9A of the groove 9. Therefore, the engagement state of the numerous small protrusions 6... reliably avoids the cracks 34 caused by stress concentration shown in Figures 8 to 11 of the conventional design. Moreover, although the pulling force of each individual small protrusion 6 is small, the numerous protrusions together exert a strong overall (pipe) pull-out resistance.

[0032] Furthermore, in the present invention, if the groove width dimension of the groove 9 is W9, the inner end 11 of the vicinity region Y where the small protrusions 6 are formed is set at an axial inward position of 0.6·W9 to 1.0·W9 from the axial position L9 of the inner tip 9A of the groove 9, and the outer end 12 of the vicinity region Y is set at an axial outward position of 0.1·W9 to 0.5·W9 from the axial position L9 of the inner tip 9A of the groove 9. As illustrated in Figure 6, the small protrusions 6 bite into the outer surface of the pipe 30 most effectively. As a result, the inner slope 15 exhibits a strong pipe pull-out force as shown in Figure 6. Furthermore, by forming the outer end 12 of the small uneven portion 6 within a narrow range of 0.1·W9 to 0.5·W9, the indentation deformation that occurs when the deformation progresses from Figure 5 to Figure 6 is made smooth.

[0033] Furthermore, the small recessed portion 6 for pipe insertion comprises a parallel threaded portion 21 on the axially inward side with a constant thread groove depth and a tapered threaded portion 22 on the axially outward side with a gradually decreasing thread groove depth towards the tip; the boundary position B between the parallel threaded portion 21 and the tapered threaded portion 22 is set to coincide with the axial position L9 of the innermost tip 9A of the recessed groove 9, or to an axially inward position within twice the thread pitch P. Therefore, under the compressed state of the sleeve 7 shown in Figure 6, the large and integrated parallel threaded portion 21 exists corresponding to the inwardly inclined surface 15, effectively providing strong pipe pull-out resistance.

[0034] Furthermore, the cross-sectional shape of the home plate-shaped groove 9 is such that the dimension W from the inner side 36 on the base end side of the sleeve 7 is based on the left-right dividing imaginary line L9 passing through the deepest point Z9 of the inner tip 9A. L The dimension W is the outer side 37 at the tip of sleeve 7. R By setting it larger than the above, the cross-sectional shape of the groove 9 is configured to be asymmetrical. Therefore, with respect to the imaginary dividing line L9, the axial inner portion (the inner circumferential surface 7A) deforms in a smaller diameter earlier than the axial outer portion (the inner circumferential surface 7A), and the amount of movement is also greater. As a result, the parallel screw portion 21 bites firmly into the pipe 30 (as shown in Figure 6), exhibiting strong pull-out resistance.

[0035] Furthermore, the cross-sectional shape of the groove portion 20N of the pipe-engaging small protrusions 6 is arc-shaped, and the cross-sectional shape of the protrusion portion 20T is a Mount Fuji shape with a flat top. As a result, the corners of the top of the protrusion portion 20T act as sharp edges, powerfully biting into the pipe 30. This provides strong pull-out resistance. Moreover, it is easy and reliable to cut and form the arc-shaped groove portion 20N. [Explanation of Symbols]

[0036] 1. Fitting body 2 Male screws 3 cap nuts 5 Outer surface 6 Small protrusions for pipe insertion 7 sleeves 7A Inner surface 9. Grooves 9A Inner tip 10 Internal storage space 11 Inner end 12 Outer end 21 Parallel thread section 21A Parallel screw grooves at the innermost position 22 Tapered thread section 36 Inner side 37 Outer side B Boundary position L9 Axial Direction Position (Imaginary line dividing left and right) P Screw Pitch W9 groove width dimension W L ,W R size Y neighboring region Z9 deepest point

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 groove (9) has a predetermined radius (R 1 ) is formed in a curved shape, On the inner circumferential surface (7A) of the sleeve (7), the axial position (L) of the innermost tip (9A) of the groove (9) 9 In the vicinity region (Y) of ), a pipe-fitting groove (6) is formed. The pipe-inserting groove portion (6) has, in a cross-section obtained by cutting the sleeve (7) in the axial direction, a plurality of grooves and a plurality of protrusions that are alternately formed in the axial direction. If the groove width dimension of the above-mentioned recessed groove (9) is (W 9), The inner end (11) of the vicinity region (Y) where the pipe-inserting groove (6) is formed is set at an axial inward position of 0.6·W9 to 1.0·W9 from the axial position (L9) of the innermost tip (9A) of the groove (9). Furthermore, the pipe joint is characterized in that the outer end (12) of the above-mentioned proximity region (Y) is set at an axially outward position of 0.1·W9 to 0.5·W9 from the axial position (L9) of the innermost tip (9A) of the groove (9).

2. The pipe-engaging groove portion (6) comprises a parallel threaded portion (21) on the axial inner side with a constant thread groove depth and a tapered threaded portion (22) on the axial outer side where the thread groove depth gradually decreases towards the tip. The boundary position (B) between the parallel thread portion (21) and the tapered thread portion (22) is the axial position (L) of the innermost tip (9A) of the groove (9). 9 ) to match, or set to an axial inward position within twice the screw pitch (P). The pipe fitting according to claim 1.

3. The cross-sectional shape of the home plate-shaped groove (9) is such that the deepest point (Z) of the innermost tip (9A) is 9 ) passing through a left-right dividing imaginary line (L 9 ) is used as the standard, The dimension (W) from the base end side of the sleeve (7) to the inner side (36) L ) to the outer side (37) of the tip side of the sleeve (7) (W R The pipe joint according to claim 1 or 2, wherein the groove (9) is set to be larger than the above-mentioned groove (9), and the cross-sectional shape of the groove (9) is asymmetrical.

4. The pipe fitting according to claim 1 or 2, wherein the cross-sectional shape of the groove portion (20N) of the pipe-fitting recessed portion (6) is arc-shaped, and the cross-sectional shape of the convex portion (20T) is a Mount Fuji shape with a flat top.

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