RING MEMBER

A ring member includes a split body having a split part split at a point in the circumferential direction and also includes a tapping screw that connects a first thin-walled portion and a second thin-walled portion forming the split part, which extend in the circumferential direction, in a state where the first thin-walled portion and the second thin-walled portion overlap one another in the radial direction of a first pipe. With the first thin-walled portion located on the radially inner side of the first pipe being fitted in an annular groove formed in the outer circumference of the spigot, the body can come into contact with a lock ring located inside a socket of a second pipe. The body has, on the second thin-walled portion, an engaging portion that is engaged with the first thin-walled portion in the axial direction of the pipes.

FIELD OF THE INVENTION

The present invention relates to a ring member used for a pipe joint. The ring member according to the present invention is fitted in a groove formed in the outer circumference of a spigot of one of pipes to be joined to each other to form a protrusion that protrudes from the outer surface of the spigot and extends in the circumferential direction of the spigot. The protrusion formed according to the present invention comes into contact with a lock ring located inside a socket of the other of the pipes to be joined to each other, thereby preventing the pipes from being separated.

BACKGROUND OF THE INVENTION

Japanese Patent Laid-Open No. 9-196262 discloses a ring member. The ring member is fitted in a groove formed in the outer circumference of a spigot of a pipe to form, on the outer circumference of the spigot, a protrusion for preventing pipes joined to each other from being separated. The ring member has a split part split at a point in the circumferential direction, which is formed by one end portion of the ring member in the circumferential direction and another end portion of the ring member in the circumferential direction. The one end portion and the other end portion overlap one another in the radial direction of the pipes, with the one end portion located on the inner side in the radial direction of the pipes and the other end portion located on the outer side in the radial direction of the pipes, and are connected to each other by a connector member.

When the spigot of one pipe is separating from the socket of the other pipe in an earthquake or the like, the ring member comes into contact with the lock ring in the socket and receives a reaction force (removal prevention force) from the lock ring. Therefore, the displacement of the spigot in the direction to separate from the socket is restricted by the ring member coming into contact with the lock ring. In this way, the spigot can be prevented from separating from the socket in an earthquake or the like.

The ring member according to Japanese Patent Laid-Open No. 9-196262 comes into contact with a lock ring in a state where the ring member is fitted in a groove and thus receives a reaction force (removal prevention force) from the lock ring. Therefore, the other end portion in the circumferential direction of the ring member, which is located on the outer side in the radial direction of the pipes when the one end portion and the other end portion overlap one another and is to come into contact with the lock ring, tends to be displaced in the opposite direction to the spigot removal direction with respect to the one end portion that is located on the inner side in the radial direction of the pipes when the one end portion and the other end portion overlap one another and is fitted in the groove. Therefore, an excessive shearing force acts on the connector member that connects the one end portion and the other end portion in the circumferential direction of the ring member to each other.

An object of the present invention is to provide a ring member that can reduce a shearing force acting on a connector member when the ring member comes into contact with a lock ring.

SUMMARY OF THE INVENTION

A ring member according to the present invention that attains the object described above is used for a pipe joint that prevents a spigot of a first pipe from separating from a socket of a second pipe. The ring member includes: a split part split in the circumferential direction at a point in the circumferential direction; one end portion in the circumferential direction and another end portion in the circumferential direction, the one end portion and the other end portion forming the split part; and a connector member that connects the one end portion and the other end portion of the split part to each other in a state where the one end portion and the other end portion overlap one another in the radial direction of the first pipe. The one end portion is located on the inner side than the other end portion in the radial direction of the first pipe. The ring member is configured in such a manner that the one end portion is fitted into a groove formed in the outer circumference of the spigot and the other end portion can come into contact with a lock ring disposed inside the socket. The ring member has, on one of the one end portion and the other end portion, an engaging portion that is engaged with the other of the one end portion and the other end portion in the axial direction of the pipes when the ring member comes into contact with the lock ring.

According to this, a reaction force (removal prevention force) from the lock ring is received by one of the one end portion and the other end portion of the split part of the ring member that is fitted in the groove via the engaging portion of the other of the one end portion and the other end portion, so that the displacement of the one end portion and the other end portion with respect to each other in the axial direction of the pipes is restricted. Therefore, the shearing force acting on the connector member due to the force that causes the displacement is reduced.

In the ring member according to the present invention, the engaging portion is preferably provided on one of the one end portion and the other end portion of the split part on the side in the axial direction of the pipes where the ring member comes into contact with the lock ring.

According to this, the one end portion and the other end portion of the split part can be engaged with each other at a position close to the position where the ring member and the lock ring come into contact with each other.

In the ring member according to the present invention, the engaging portion is preferably provided on the other end portion and extends inwardly in the radial direction of the pipes.

According to this, the engaging portion can be fitted into the groove of the spigot, and the one end portion and the other end portion forming the split part can be engaged with each other in the groove.

With the ring member according to the present invention, one of the one end portion and the other end portion forming the split part has the engaging portion that is engaged with the other of the one end portion and the other end portion forming the split part when the ring member comes into contact with the lock ring. Therefore, the reaction force (removal prevention fore) from the lock ring that occurs as a result of the ring member coming into contact with the lock ring is received by the other end portion forming the split part and is also received by the one end portion forming the split part via the engaging portion. Therefore, the displacement of the one end portion and the other end portion with respect to each other in the axial direction of the pipes, which would otherwise occur if only the other end portion forming the split part receives the reaction force (removal prevention force) from the lock ring, is unlikely to occur. Therefore, the shearing force acting on the connector member is reduced, and the load on the connector member is reduced. Therefore, when the ring member and the lock ring come into contact with each other in an earthquake or the like, the damage to or deformation of the connector member of the ring member caused by the reaction force (removal prevention force) from the lock ring is unlikely to occur. In this way, the seismic performance of the ring member and therefore of the pipe joint to which the ring member is attached can be improved.

DETAILED DESCRIPTION OF THE INVENTION

In the following, a ring member20according to a first embodiment of the present invention will be described.

As shown inFIGS.1and2, the ring member20according to the first embodiment of the present invention is used for a pipe joint10.

The pipe joint10has a spigot11and a socket12. The spigot11is formed at an end of a first pipe10A. The socket12is formed at an end of a second pipe10B that is to be joined to the first pipe10A. The spigot11is inserted into the socket12. With the pipe joint10, the ring member20protrudes from an outer circumference11aof the spigot11and comes into contact with a lock ring13that is located inside the socket12, thereby preventing the spigot11from separating from the socket12.

In an inner circumference of a distal end portion of the socket12, a housing groove14for a sealing member is formed. A sealing member15made of rubber is fitted in the housing groove14. In a part of the inner circumference of the socket12deeper than the housing groove14, a housing groove16for the lock ring is formed. The lock ring13is fitted in the housing groove16. A ring17for centering made of rubber is interposed between an inner circumference surface of the housing groove16and an outer circumference surface of the lock ring13. The ring17aligns the axis of the lock ring13with the axis of the socket12.

In the outer circumference11aof a distal end portion of the spigot11, an annular groove18is formed. The ring member20is fitted in the annular groove18.

The ring member20is fitted in the annular groove18to form a protrusion that comes into contact with the lock ring13. As shown inFIG.2, the ring member20is formed by a split body21having a split part22split in the circumferential direction at a point in the circumferential direction. In other words, the ring member20is an open ring member. The split part22of the ring member20has a first thin-walled portion23having a curved shape located on the inner circumference side and a second thin-walled portion24having a curved shape located on the outer circumference side. The first thin-walled portion23is formed at one end portion in the circumferential direction of the body21, which constitutes the split part22. The inner circumference surface of the first thin-walled portion23is continuous with the inner circumference surface of the body21. In other words, the inner circumference surface of the first thin-walled portion23extends at the same radial position with the same curvature as the inner circumference surface of the body21. The second thin-walled portion24is formed at the other end portion in the circumferential direction of the body21, which constitutes the split part22. The outer circumference surface of the second thin-walled portion24is continuous with the outer circumference surface of the body21. In other words, the outer circumference surface of the second thin-walled portion24extends at the same radial position with the same curvature as the outer circumference surface of the body21.

The first thin-walled portion23and the second thin-walled portion24overlap one another in the radial direction of the ring member20(the radial direction of the first pipe10A). The first thin-walled portion23and the second thin-walled portion24are arranged in such a manner that the outer circumference surface of the first thin-walled portion23is in contact with the inner circumference surface of the second thin-walled portion24. The split part22of the body21is formed so that the sum of the thickness of the first thin-walled portion23(the thickness in the radial direction of the ring member20) and the thickness of the second thin-walled portion24(the thickness in the radial direction of the ring member20) is equal to the thickness of the other part of the body21than the split part22(the thickness in the radial direction of the ring member20). The first thin-walled portion23and the second thin-walled portion24overlap one another over a predetermined length in the circumferential direction and each have a length in the circumferential direction greater than the length of the part thereof overlapping the other. With the first thin-walled portion23and the second thin-walled portion24configured as described above, the ring member20can be increased or decreased in diameter to some extent while the first thin-walled portion23and the second thin-walled portion24are kept overlapping one another.

As shown inFIGS.2and3, the first thin-walled portion23is located on the inner circumference side of the ring member20when overlapping with the second thin-walled portion24. The first thin-walled portion23is fitted into the annular groove18of the spigot11when the ring member20is attached to the outer circumference11aof the spigot11. The annular groove18has a rectangular cross section. The ring member20also has a rectangular cross section that corresponds to that of the annular groove18. The thickness of the first thin-walled portion23(the thickness in the radial direction of the ring member20) is approximately equal to or slightly smaller than the depth of the angular groove18in the radial direction of the spigot11. That is, the first thin-walled portion23is totally fitted into the annular groove18. The width dimension of the first thin-walled portion23(the dimension in the axial direction of the ring member20) is smaller than the dimension in the width direction of the annular groove18(the dimension in the axial direction of the pipe joint10).

The second thin-walled portion24has a L-shaped cross section. When the ring member20is attached to the outer circumference11aof the spigot11, the second thin-walled portion24overlaps with the first thin-walled portion23and is located on the outer circumference side of the ring member20. The second thin-walled portion24protrudes in the radial direction of the spigot11from the outer circumference11aof the spigot11when the first thin-walled portion23is fitted into the annular groove18of the spigot11. The second thin-walled portion24serves as a protrusion of the spigot11that comes into contact with the lock ring13. That is, the second thin-walled portion24comes into contact with the lock ring13when the spigot11is separating from the socket12.

As shown inFIGS.3and4, the second thin-walled portion24has a contact portion25and an engaging portion26. The engaging portion26extends in the vertical direction (toward the inner side in the radial direction) from one end in the axial direction of the contact portion25, and thus the second thin-walled portion24has the L-shaped cross section as described above. The contact portion25rests on the outer circumference surface of the first thin-walled portion23. The contact portion25protrudes from the outer circumference11aof the spigot11when the ring member20is fitted into the annular groove18. Since the contact portion25protrudes from the outer circumference11aof the spigot11, the contact portion25comes into contact with the lock ring13when the spigot11is separating from the socket12. Therefore, the spigot11is prevented from separating from the socket12. The end portion of the contact portion25on the tip end side of the spigot11in the axial direction, that is, the end portion of the contact portion25opposite to the end portion that comes into contact with the lock ring13, is tapered toward the tip end of the spigot11and thus has an inclined surface27.

When the contact portion25comes into contact with the lock ring13, the engaging portion26is engaged with the first thin-walled portion23. The engaging portion26protrudes inwardly in the radial direction from the contact portion25. The engaging portion26is formed at the end of the contact portion25of the second thin-walled portion24that is located toward the lock ring13. When the ring member20is attached to the outer circumference11aof the spigot11, the engaging portion26is fitted into a part of the annular groove18of the spigot11that is located toward the lock ring13and is not occupied by the first thin-walled portion23. The length of the engaging portion26protruding inwardly in the radial direction is approximately equal to or slightly shorter than the depth of the annular groove18in the radial direction of the spigot11.

A hole28for insertion of a connector member for connection with the first thin-walled portion23is formed in a part of the second thin-walled portion24, and the hole28penetrates the second thin-walled portion24in the radial direction of the pipe. The hole28has a wide portion28aon the outer circumference surface side of the second thin-walled portion24. In the state where the first thin-walled portion23and the second thin-walled portion24overlap one another in the radial direction of the first pipe10A, a tapping screw29, which is an example of the connector member, is inserted in the hole28and screwed into the first thin-walled portion23to connect the first thin-walled portion23and the second thin-walled portion24to each other. In this state, the head of the tapping screw29is housed in the wide portion28a.Since the first thin-walled portion23and the second thin-walled portion24are connected by the tapping screw29, the ring member20is fixed to the outer circumference of the spigot11with a part of the ring member20protruding in the radial direction from the outer circumference11aof the spigot11of the first pipe10A. The first thin-walled portion23is connected to the second thin-walled portion24in a state where the first thin-walled portion23is located in a space defined by a curved surface25aof the second thin-walled portion24and a first vertical surface26aof the engaging portion26. The curved surface25aof the second thin-walled portion24is a curved surface on the inner side in the radial direction of the contact portion25of the second thin-walled portion24. The first vertical surface26aof the engaging portion26is a side surface of the engaging portion26located toward the first thin-walled portion23that extends in the radial direction perpendicularly to the contact portion25. Since the first thin-walled portion23and the second thin-walled portion24overlap one another, the first thin-walled portion23is held in the annular groove18in the state where the first thin-walled portion23is covered by the contact portion25and engaging portion26of the second thin-walled portion24.

Next, functions of the ring member20will be described. As shown inFIG.4, when the spigot11with the ring member20attached thereto is separating from the socket12, the ring member20fitted in the annular groove18comes into contact with the lock ring13. Since the ring member20comes into contact with the lock ring13, the displacement of the spigot11in a removal direction R is restricted by the lock ring13. In this state, at the split part22of the body21of the ring member20, the second thin-walled portion24is in contact with the lock ring13.

When the ring member20comes into contact with the lock ring13, the ring member20receives a reaction force (removal prevention force) from the lock ring13in the opposite direction to the removal direction R of the spigot11. Specifically, the second thin-walled portion24of the split part22of the body21of the ring member20receives the reaction force (removal prevention force) from the lock ring13. More specifically, the second thin-walled portion24receives the reaction force (removal prevention force) from the lock ring13at a second vertical surface25bof the contact portion25. The second vertical surface25bof the contact portion25is a vertical surface that protrudes from the outer circumference11aof the spigot11in the radial direction of the pipe and faces toward the lock ring13when the body21is fitted in the annular groove18.

When the second thin-walled portion24receives the reaction force (removal prevention force) from the lock ring13, the second thin-walled portion24would otherwise be displaced toward the first thin-walled portion23in the opposite direction to the removal direction R of the spigot11. At this point in time, however, the first vertical surface26aof the engaging portion26of the second thin-walled portion24comes into contact with a third vertical surface23aof the first thin-walled portion23in the annular groove18. The third vertical surface23aof the first thin-walled portion23is a surface of the first thin-walled portion23that is perpendicular to the bottom surface of the annular groove18when the first thin-walled portion23is fitted in the annular groove18and faces the first vertical surface26aof the engaging portion26of the second thin-walled portion24. The third vertical surface23aof the first thin-walled portion23fitted in the annular groove18receives the reaction force (removal prevention force) from the lock ring13via the engaging portion26of the second thin-walled portion24, so that the displacement of the second thin-walled portion24with respect to the first thin-walled portion23in the opposite direction to the removal direction R of the spigot11is restricted. In this way, even when the second thin-walled portion24receives a reaction force (removal prevention force) from the lock ring13, the displacement of the second thin-walled portion24with respect to the first thin-walled portion23is unlikely to occur. Therefore, the shearing force acting on the tapping screw29as the connector member as a result of the displacement of the second thin-walled portion24with respect to the first thin-walled portion23is reduced.

As described above, according to the first embodiment, the second thin-walled portion24forming the split part22of the body21of the ring member20has the engaging portion26that is engaged with the first thin-walled portion23that forms the split part22when the body21of the ring member20comes into contact with the lock ring13. Therefore, the reaction force (removal prevention force) from the lock ring13that occurs when the body21comes into contact with the lock ring13is received by the second thin-walled portion24and is also received by the first thin-walled portion23via the engaging portion26. Therefore, the displacement of the second thin-walled portion24with respect to the first thin-walled portion23, which would occur if only the second thin-walled portion24receives the reaction force (removal prevention force) from the lock ring13, is unlikely to occur. Therefore, the shearing force acting on the tapping screw29as a result of the displacement of the second thin-walled portion24with respect to the first thin-walled portion23is reduced, and the load on the tapping screw29is reduced. Therefore, when the ring member20and the lock ring13come into contact with each other in an earthquake or the like, the damage to or deformation of the tapping screw29caused by the reaction force (removal prevention force) from the lock ring13is unlikely to occur. In this way, the seismic performance of the ring member20can be improved.

As described above, according to the first embodiment, the second thin-walled portion24has the engaging portion26that is to be engaged with the first thin-walled portion23on the side where the contact portion25comes into contact with the lock ring13. However, the present invention is not limited to this. For example, like a ring member20A (second embodiment) shown inFIG.5, an engaging portion26may be provided in a middle part of a second thin-walled portion24in the axial direction. In this case, a first recess portion23bthat can be engaged with the engaging portion26is formed in a middle part of a first thin-walled portion23. The engaging portion26is fitted in the first recess portion23b.The other components than those described above are the same as those in the first embodiment. The first recess portion23bis a groove extending in the circumferential direction in which the engaging portion26of the second thin-walled portion24can be fitted.

Although the second thin-walled portion24has the engaging portion26in the first embodiment, the present invention is not limited to this. As shown inFIGS.6to8, a first thin-walled portion23to be fitted into an annular groove18may have an engaging portion26. In these cases, the engaging portion26protrudes outwardly in the radial direction.

When the first thin-walled portion23has the engaging portion26, like a ring member20B (third embodiment) shown inFIG.6, the engaging portion26may be provided on the side where the ring member20B comes into contact with a lock ring13. In this case, the engaging portion26comes into contact with not only the lock ring13but also a second vertical surface25bof a second thin-walled portion24. The second vertical surface25bis an end surface of the thin-walled portion24located toward the lock ring13.

Like a ring member20C (fourth embodiment) shown inFIG.7, an engaging portion26may be provided on a first thin-walled portion23on the opposite side to a lock ring13. In this case, the engaging portion26comes into contact with a fourth vertical surface25C of a second thin-walled portion24. The fourth vertical surface25C is an end surface of the second thin-walled portion24located on the opposite side to the lock ring13.

Like a ring member20D (fifth embodiment) shown inFIG.8, an engaging portion26may be provided on a middle part of a first thin-walled portion23in the axial direction. In this case, a second recess portion25dthat can be engaged with the engaging portion26fitted therein is formed in a middle part of a second thin-walled portion24. The second recess portion25dis a groove extending in the circumferential direction in which the engaging portion26of the first thin-walled portion23can be fitted. The other components than those described above in the third to fifth embodiments are the same as those in the first embodiment.

Although the first thin-walled portion23and the second thin-walled portion24are connected to each other by the tapping screw29as a fastener element in the first to fifth embodiments, the present invention is not limited to this. The first thin-walled portion23and the second thin-walled portion24may be connected to each other by connector members formed by other fastener elements, such as a rivet, or other connector members of the non-fastening type.

REFERENCE SIGNS LIST