Pipe joint structure

Abstract

To provide a pipe joint structure which does not excessively push-press a lock ring to a spigot.SOLUTION: A lock ring 17 is attached to a spigot external peripheral face of another pipe 11, and engaged with a lock ring accommodation groove 16 in a pipe axial direction. A one-side release prohibition face 26 formed at a one-side face which is oriented to a receptacle tip side comes into line-contact with an opening edge 16a of the lock ring accommodation groove 16 around a pipe axial core,and forms another-side release prohibition face 27 opposing a spigot protrusion 18 in the pipe axial direction, and a surface normal 30 of a tangent plane 29 at a contact point 28 where an opening edge 16a of the lock ring accommodation groove 16 abuts on the one-side release prohibition face 26 passes through the other-side release prohibition face 27.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pipe joint structure and contributes to the technology of preventing pipes from slipping out. [Background technology]

[0002] Conventionally, a pipe joint structure having an expansion and contraction function and a separation prevention function is, for example, described in Patent Document 1. As shown in Fig. 7, in this structure, the insertion port 4 of one pipe 3 is inserted into the socket 2 of the other pipe 1, a lock ring 6 that is divided in the circumferential direction is accommodated in a lock ring accommodation groove 5 formed on the inner peripheral surface of the socket 2, and an insertion port protrusion 7 is formed on the outer peripheral surface of the insertion port 5.

[0003] When a large tensile force acts on the pipes 1, 2 due to an earthquake or the like, the insertion port 4 and the receiving port 2 move apart in the axial direction of the pipes, and the insertion port protrusion 7 engages with the lock ring 6 as shown in the figure.

[0004] At this time, a tensile force acts on the lock ring 6, separating the insertion port 4 and the receiving port 2 from each other in the direction of the pipe axis, and the opening edge 8 of the lock ring accommodating groove 5 abuts on the front side of the lock ring 6 in the direction of the pipe axis, and the insertion port protrusion 7 abuts on the back side, preventing the receiving port 2 and the insertion port 4 from coming loose from each other via the lock ring 6.

[0005] At the contact point where the opening edge 8 of the lock ring receiving groove 5 and the tapered surface 9 on the receiving opening side of the lock ring 6 come into contact, a tensile force acting between the pipes 1 and 2 acts as an external force F that pushes the tapered surface 9 toward the pipe axis center with the contact point as the point of action. This external force F acts on the lock ring 6 as a component force F1 of a surface component perpendicular to the tangent plane at the contact point on the tapered surface 9 and a component force F2 of a component parallel to the tangent plane. The line of action 10 of the component force F1 of the surface component perpendicular to the tangent plane extends in the surface normal direction of the tangent plane. Here, the gradient of the tapered surface 9 is set so that the surface normal passes through the inner surface of the lock ring 6 and faces the insertion port 4. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication 2005-140138 Summary of the Invention [Problem to be solved by the invention]

[0007] In the conventional configuration, a counterclockwise moment M due to a surface component force F1 acts on the lock ring 6 on the back side of the lock ring 6 where the insertion port protrusion 9 comes into contact, with the inner radial edge of the ring as center A, and an external force due to a tensile force acts as a force pressing the lock ring 6 against the insertion port 4, preventing the lock ring 6 from floating up.

[0008] However, when an earthquake of a large scale occurs and a large tensile force that exceeds the design assumed value acts on the pipes 1 and 3, the lock ring 6 is excessively pressed against the insertion port 4, so it is necessary to increase the thickness of the pipe to resist this force.

[0009] The present invention is devised to solve the above-mentioned problems, and has an object to provide a pipe joint structure that can suppress the force pressing the lock ring against the insertion port. [Means for solving the problem]

[0010] In order to solve the above problems, the pipe joint structure of the present invention has a separation prevention structure between a socket of one pipe and an insertion port of the other pipe to be inserted into the socket, and the separation prevention structure comprises a lock ring accommodating groove formed around the pipe axis on the inner peripheral surface of the socket, a lock ring to be accommodated in the lock ring accommodating groove, and an insertion port protrusion formed on the outer peripheral surface of the insertion port closer to the insertion port tip side than the lock ring and engaging with the lock ring in the pipe axial direction, the lock ring is attached to the outer peripheral surface of the insertion port of the other pipe and engages with the lock ring accommodating groove in the pipe axial direction, a one-side separation prevention surface formed on one side facing the socket tip side contacts an opening edge of the lock ring accommodating groove around the pipe axis, and the other side facing the insertion port tip side forms an other-side separation prevention surface that faces the insertion port protrusion in the pipe axial direction, and the surface normal of the tangent plane at the point of contact where the opening edge of the lock ring accommodating groove meets the one-side separation prevention surface passes through the other-side separation prevention surface.

[0011] In the pipe joint structure of the present invention, a surface normal to a tangential plane passing through the other-side separation prevention surface passes through an inner peripheral edge of a ring of the other-side separation prevention surface.

[0012] In the pipe joint structure of the present invention, the surface normal of the tangent plane passing through the other-side withdrawal prevention surface is characterized in that it passes through the other-side withdrawal prevention surface between the inner ring edge of the other-side withdrawal prevention surface and the position where the other-side withdrawal prevention surface contacts the outer peripheral edge of the insertion port protrusion.

[0013] In the pipe joint structure of the present invention, the lock ring is characterized in that the one-side separation prevention surface is formed in a conical surface shape.

[0014] In the pipe joint structure of the present invention, the lock ring is characterized in that the one-side separation prevention surface is curved along an arc having a center on a surface normal to a tangent plane.

[0015] In the pipe joint structure of the present invention, the center of the arc of the one-side separation prevention surface is at the intersection of a surface normal to a tangential plane and the other-side separation prevention surface. Effect of the Invention

[0016] With the above-described configuration, the force acting in the pipe axial direction from the opening edge at the point of contact where the opening edge of the lock ring accommodating groove abuts on the one-side separation prevention surface acts on the lock ring as a component force along the surface normal to the tangent plane and a component force along the tangent plane.

[0017] And, since the surface normal of the tangential plane passes through the other-side separation prevention surface, the line of action of the component force along the surface normal of the tangential plane passes through the other-side separation prevention surface.

[0018] The smaller the angle of the surface normal to the ring axis, the larger the force component directed toward the ring axis and the smaller the force component directed toward the ring radial direction. Therefore, compared to when the surface normal to the tangent plane passes through the inner circumferential surface of the lock ring, when the surface normal to the tangent plane passes through the other-side separation prevention surface, the force component directed toward the ring radial direction of the force component along the surface normal to the tangent plane is smaller, and the force of the external force due to the tensile force pressing the lock ring against the insertion port can be suppressed. [Brief description of the drawings]

[0019] [Figure 1] FIG. 2 is a cross-sectional view taken along the pipe axis direction, showing a pipe joint structure according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing a main part of the pipe joint structure in the embodiment; [Diagram 3] FIG. 1 is a schematic diagram showing a main part of a pipe joint structure in the embodiment, illustrating a relationship between a component force F1 along a surface normal direction of a tangent plane, a component F11 directed in the pipe axial direction, and a component F12 directed in the pipe radial direction. [Figure 4] FIG. 2 is a schematic diagram showing a main part of the pipe joint structure in the embodiment, illustrating the relationship between a tangent plane, a surface normal, and a center position of a circular arc. [Diagram 5] FIG. 13 is a schematic diagram showing a main part of a pipe joint structure according to another embodiment of the present invention; [Figure 6] FIG. 13 is a schematic diagram showing a main part of a pipe joint structure according to still another embodiment of the present invention; [Figure 7] Schematic diagram showing the main part of a conventional pipe joint structure DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Example 1 1 and 2, an insertion port 14 of one pipe 13 is inserted into a socket 12 of the other pipe 11. A seal pressure contact surface 15 and a lock ring accommodating groove 16 are formed on the inner surface of the socket 12, successively from the tip side of the socket 12 toward the back end side of the socket in the pipe axial direction.

[0021] A single circumferentially split lock ring 17 is accommodated in this lock ring accommodating groove 16, and an insertion port protrusion 18 is provided on the outer peripheral surface of the insertion port closer to the tip of the insertion port than the lock ring accommodating groove 16 and the lock ring 17, thereby forming an anti-detachment structure between the receiving port 12 of one tube 11 and the receiving port 14 of the other tube 13 inserted into the receiving port 12.

[0022] The insertion port 14 is inserted into the lock ring 17 while it is being expanded in the ring radial direction by elastic deformation inside the lock ring receiving groove 16, and the insertion port protrusion 18 passes through the lock ring 17 and the insertion port 14 is inserted to a predetermined position in the socket 12. When the lock ring 17 returns in the ring radial direction inside the lock ring receiving groove 16, the insertion port protrusion 18 engages with the lock ring 17 in the pipe axial direction. The lock ring 17 is then attached to the outer circumferential surface of the insertion port of the other pipe 13, and the lock ring 17 and the lock ring receiving groove 16 engage with each other in the pipe axial direction.

[0023] On the outer periphery of the insertion port 14, there are arranged a resin backup ring 19, a rubber seal material 20, and a press ring 21 which is capable of coming into contact with the seal material 20 and presses the seal material 20.

[0024] Then, multiple bolts 23 inserted into holes 22 formed in the flange 21 of the receiving port 12 are passed through holes 24 formed in the pressure ring 21, and nuts 25 attached to the bolts 23 are tightened to press the pressure ring 21 toward the rear end of the receiving port 12, compressing the sealing material 20 between the sealing material pressure contact surface 15 and the outer periphery of the insertion port 14, and bringing the sealing material 20 into contact with the sealing material pressure contact surface 15 to join the receiving port 12 and the insertion port 14.

[0025] The lock ring 17 has one side prevention surface 26 formed on one side facing the socket tip side, which contacts one opening edge 16a of the lock ring accommodating groove 16 around the tube axis, and the other side facing the socket tip side forms an other side prevention surface 27 that faces the socket protrusion 18 in the tube axis direction. The other side prevention surface 27 of the lock ring 17 forms a flat surface along the ring radius direction of the lock ring 17, and the inner peripheral surface of the lock ring 17 forms a flat surface along the ring axis direction of the lock ring 17.

[0026] The surface of the insertion port protrusion 18 facing the other side removal prevention surface 27 of the lock ring 17 forms a flat surface along the ring radial direction of the lock ring 17, and abuts against the other side removal prevention surface 27 over the entire ring radial direction from the innermost position of the insertion port protrusion 18 in the pipe radial direction to the outermost position in the pipe radial direction.

[0027] In other words, the insertion port protrusion 18 contacts the other-side withdrawal prevention surface 27 of the lock ring 17 between the inner peripheral edge 31 on the inner side of the ring radial direction of the other-side withdrawal prevention surface 27, i.e., the innermost position in the ring radial direction of the other-side withdrawal prevention surface 27 that corresponds to the innermost position of the insertion port protrusion 18, and the outermost position in the ring radial direction of the other-side withdrawal prevention surface 27 where the other-side withdrawal prevention surface 27 contacts the outer peripheral edge in the pipe radial direction of the insertion port protrusion 18, i.e., the outermost position in the pipe radial direction of the insertion port protrusion 18. Here, the innermost position is point A and the outermost position is point B. Note that points A and B are included in the other-side withdrawal prevention surface 27.

[0028] At a contact point 28 where one opening edge 16a of the lock ring accommodating groove 16 comes into contact with the one-side separation prevention surface 26, a surface normal 30 of the tangent plane 29 passes through the other-side separation prevention surface 27. Here, the one-side separation prevention surface 26 curves along an arc having a center S1 on the surface normal to the tangent plane 29, and further, the center S1 of the arc of the one-side separation prevention surface 26 is at the intersection of the surface normal 30 of the tangent plane 29 and the other-side separation prevention surface 27.

[0029] Furthermore, as shown in Figure 2, the surface normal 30 of the tangent plane 29 passing through the other-side withdrawal prevention surface 27 passes through the inner peripheral edge 31 on the inner side of the ring radial direction of the other-side withdrawal prevention surface 27, i.e., point A, which is the innermost position in the ring radial direction of the other-side withdrawal prevention surface 27 that corresponds to the insertion port protrusion 18.

[0030] With the above configuration, when a large tensile force acts on the pipes 11, 13 due to an earthquake or the like, the insertion port 14 and the receiving port 12 move away from each other in the axial direction of the pipes, changing from the state shown in Figure 1 to the state shown in Figure 2, and the insertion port protrusion 18 engages with the lock ring 17.

[0031] At this time, a tensile force acts on the lock ring 17, separating the insertion port 14 and the receiving port 12 from each other in the direction of the pipe axis, and the opening edge 16a of the lock ring accommodating groove 16 abuts against one side separation prevention surface 26 of the lock ring 17 in the direction of the pipe axis, and the insertion port protrusion 18 abuts against the other side separation prevention surface 27, so that the receiving port 12 and the insertion port 14 are prevented from coming off from each other via the lock ring 17.

[0032] At a contact point 28 where the opening edge 16a of the lock ring accommodating groove 16 and the one-side separation prevention surface 26 of the lock ring 17 come into contact with each other, a tensile force acting between the pipes 11, 13 with the contact point 28 as a point of action acts as an external force F that pushes the one-side separation prevention surface 26 in the pipe axial direction. This external force F acts on the lock ring 17 as a component force F1 perpendicular to a tangent plane 29 at the contact point 28 of the one-side separation prevention surface 26 and a component force F2 parallel to the tangent plane 29. The line of action of the component force F1 perpendicular to the tangent plane 29 extends in the direction normal to the tangent plane 29.

[0033] Here, since the surface normal 30 of the tangent plane 29 passes through point A, which is the innermost position in the ring radial direction of the other-side separation prevention surface 27, the moment due to the component force F1 along the surface normal 30 does not act on the lock ring 17 around point A, which is the innermost position.

[0034] Furthermore, the one-side departure prevention surface 26 curves along an arc having center S1 on the surface normal to the tangent plane 29, and center S1 of the arc of the one-side departure prevention surface 26 is at the intersection of the surface normal 30 of the tangent plane 29 and the other-side departure prevention surface 27. Therefore, even if the position of the contact point 28 where one opening edge 16a of the lock ring accommodating groove 16 and the one-side departure prevention surface 26 come into contact is shifted due to assembly errors, etc., the surface normal 30 of the tangent plane 29 will pass through the center S1 of the arc on the other-side departure prevention surface 27.

[0035] Therefore, by making the center S1 of the arc of the one-side escape prevention surface 26 the intersection point between the surface normal 30 of the tangential plane 29 and the other-side escape prevention surface 27, it is possible to reliably set the position where the surface normal 30 of the tangential plane 29 passes through the other-side escape prevention surface 27.

[0036] As shown in FIG. 3, the component force F1 along the surface normal to the tangent plane becomes larger as the angle of the surface normal 30 with respect to the ring axis becomes smaller, so that the force component F11 directed toward the ring axis becomes larger and the force component F12 directed in the ring radial direction becomes smaller.

[0037] 2, when the surface normal 30 passes through point A, which is the innermost position of the other-side separation prevention surface 27 of the lock ring 17, the angle of the surface normal 30 with respect to the ring axis is smaller than when the surface normal 30 passes through the inner peripheral surface of the lock ring 17 as in the conventional case. Therefore, the component F12 in the ring radial direction of the component force F1 along the surface normal 30 is smaller, and the force generated at the insertion port 14 can be suppressed. Example 2 As shown in Figure 4, when center S2 of the arc of one-side departure prevention surface 26 is displaced in the ring radial direction on the other-side departure prevention surface 27, the shape of one-side departure prevention surface 26 changes in accordance with the change in the distance between center S2 of the arc and contact point 28 where opening edge 16a of lock ring accommodating groove 16 and one-side departure prevention surface 26 of lock ring 17 come into contact.

[0038] The position where the surface normal 30 of the tangential plane 29 passes through the other-side separation prevention surface 27 also moves in the ring radial direction as the center S2 of the arc moves.

[0039] When the surface normal 30 of the tangent plane 29 passes through the other-side removal prevention surface 27 between point A at the innermost position and point B at the outermost position, a clockwise moment M1 due to a component force F1 along the surface normal 30 acts on the lock ring 17, centered at point A at the innermost position where the insertion port protrusion 18 contacts the other-side removal prevention surface 27 of the lock ring 17.

[0040] At this time, because the surface normal 30 passes through the other-side separation prevention surface 27 of the lock ring 17, the angle of the surface normal 30 with respect to the ring axis is smaller than when the surface normal 30 passes through the inner peripheral surface of the lock ring 17 as in the conventional case. Therefore, the ring radial direction component F12 of the component force F1 along the surface normal 30 is smaller, and the force generated at the insertion port 14 can be suppressed.

[0041] Furthermore, when an external force that exceeds the rigidity of lock ring 17 against torsion is applied, the center of the moment acting on lock ring 17 moves from point A, which is the innermost position in the pipe radial direction of insertion port protrusion 18, to point B, which is the outermost position in the pipe radial direction.

[0042] As a result, a counterclockwise moment M2 due to a component force F1 along the surface normal 30 acts on the lock ring 17 about point B at the outermost position, preventing the lock ring 17 from lifting up from the insertion port 14. Example 3 As shown in FIG. 5, it is also possible to make one side separation prevention surface 26 of the lock ring 17 a tapered surface.

[0043] In this case, by adjusting the gradient of the taper, it is possible to configure the surface normal 30 of the tangent plane 29 to pass through point A at the innermost position, or to configure the surface normal 30 of the tangent plane 29 to pass through the other-side separation prevention surface 27 between point A at the innermost position and point B at the outermost position. Example 4 6, it is also possible to form the insertion port protrusion 18 by build-up welding, and to configure the insertion port protrusion 18 to contact the other-side separation prevention surface 27 of the lock ring 17 only at point A, which is the innermost position. Here, the one-side separation prevention surface 26 curves along an arc having a center S1 on the surface normal to the tangent plane 29, and further, the center S1 of the arc of the one-side separation prevention surface 26 is at the intersection of the surface normal 30 of the tangent plane 29 and the other-side separation prevention surface 27.

[0044] In this case, a surface normal 30 of the tangent plane 29 passing through the other-side separation prevention surface 27 passes through point A, which is the innermost position in the ring radial direction of the other-side separation prevention surface 27. Around point A, which is the innermost position, a moment due to component force F1 along the surface normal 30 does not act on the lock ring 17.

[0045] At this time, because the surface normal 30 passes through point A, which is the innermost position of the other-side separation prevention surface 27 of the lock ring 17, the angle of the surface normal 30 with respect to the ring axis is smaller than when the surface normal 30 passes through the inner peripheral surface of the lock ring 17 as in the conventional case. Therefore, the ring radial direction component F12 of the component force F1 along the surface normal 30 is smaller, and the force generated at the insertion port 14 can be suppressed.

[0046] In the above embodiment, the tensile force has been described, but even if the joint is bent, the contact point does not change and the line of action always passes through the other-side separation prevention surface, so the same effect is achieved. [Explanation of symbols]

[0047] 11 One tube 12 socket 13 The other tube 14 Insertion port 15 Seal pressure contact surface 16 Lock ring receiving groove 16a Opening edge 17 Lock Ring 18 Insertion port protrusion 19 Backup ring 20 Sealing material 21 Push Ring 22 Flange hole 23 Volts 24 Push ring hole 25 Nut 26 One side separation prevention surface 27 Other side escape prevention surface 28 Contacts 29 Tangent plane 30 surface normals 31 Inner edge M1,M2 moments

Claims

1. A separation prevention structure is provided between the socket of one pipe and the insertion port of the other pipe to be inserted into the socket, The separation prevention structure includes a lock ring receiving groove formed around the pipe axis on the inner peripheral surface of the socket, a lock ring received in the lock ring receiving groove, and a socket protrusion formed on the outer peripheral surface of the socket closer to the tip end of the socket than the lock ring and engaging with the lock ring in the pipe axis direction, The lock ring is attached to the outer circumferential surface of the insertion port of the other pipe, engages with the lock ring receiving groove in the pipe axial direction, and a one-side removal prevention surface formed on one side surface facing the receiving port tip side contacts the opening edge of the lock ring receiving groove around the pipe axis, and the other side surface facing the insertion port tip side forms an other-side removal prevention surface that faces the insertion port protrusion in the pipe axial direction. The one-side separation prevention surface is a conical surface, A pipe joint structure, characterized in that a surface normal to a tangential plane at a contact point where an opening edge of the lock ring accommodating groove abuts on the one-side separation prevention surface passes through the other-side separation prevention surface.

2. A pipe fitting having a structure for preventing separation between the receiving port of one pipe and the insertion port of the other pipe to be inserted into the receiving port, The separation prevention structure includes a lock ring receiving groove formed around the pipe axis on the inner peripheral surface of the socket, a lock ring received in the lock ring receiving groove, and a socket protrusion formed on the outer peripheral surface of the socket closer to the tip end of the socket than the lock ring and engaging with the lock ring in the pipe axis direction, The lock ring is attached to the outer circumferential surface of the insertion port of the other pipe, engages with the lock ring receiving groove in the pipe axial direction, and a one-side removal prevention surface formed on one side surface facing the receiving port tip side contacts the opening edge of the lock ring receiving groove around the pipe axis, and the other side surface facing the insertion port tip side forms an other-side removal prevention surface that faces the insertion port protrusion in the pipe axial direction. The one-side separation prevention surface is curved along a circular arc having a center on a surface normal to a tangent plane at a contact point where an opening edge of the lock ring receiving groove contacts the one-side separation prevention surface, A pipe joint structure, characterized in that the surface normal passes through the other side separation prevention surface.

3. 3. The pipe joint structure according to claim 2, wherein the center of the arc of the one-side separation prevention surface is at the intersection of a surface normal to a tangential plane and the other-side separation prevention surface.

4. 4. The pipe joint structure according to claim 1, wherein a surface normal to a tangential plane passing through the other-side separation prevention surface passes through an inner peripheral edge of a ring of the other-side separation prevention surface.

5. A pipe joint structure as described in any one of claims 1 to 3, characterized in that the surface normal of a tangent plane passing through the other-side withdrawal prevention surface passes through the other-side withdrawal prevention surface between the inner ring edge of the other-side withdrawal prevention surface and the position where the other-side withdrawal prevention surface contacts the outer peripheral edge of the insertion port protrusion.

Images