JP2013068238A - Pipe joint structure and fiber reinforced plastic tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve both of making it easy to connect pipe bodies with each other and making the tube bodies hard to come out after being connected with each other once.SOLUTION: Tube joint structure is configured so as to form, on a spigot 4 of a spigot side pipe body 3, a reverse taper 6 which reduces the outer diameter of the spigot 4 from tip side toward the innermost side and to provide, on a socket 2 of a socket side tube body 1, an annular sealing piece 9 abutting against the reverse taper 6. By forming the reverse taper 6, a gap between the inner surface of the socket 2 and the outer surface of the spigot 4 spreads larger as a magnitude of insertion becomes larger when inserting the spigot 4 into the socket 2. Therefore, the larger the magnitude of insertion becomes, the smaller contact resistance in each of the sealing piece 9 becomes gradually, and thereby, the insertion can be performed smoothly. In addition, a force of a pipe axis direction is applied on the sealing piece 9 toward a spigot side by the reverse taper 6 when a pull-out force is applied on the spigot side pipe body 3. Therefore, the sealing piece 9 can be lifted up smoothly and action for preventing the pipe bodies from falling out is exhibited speedily.

Description

  The present invention relates to a pipe joint structure for connecting pipe bodies to each other, and a fiber reinforced plastic pipe adopting the pipe joint structure.

  In underground burial work such as power cables and communication cables, pipes such as fiber reinforced plastic (FRP) pipes are connected while being laid in the ground, and the power cables and the like are passed through the laid pipes. In order to perform this laying operation smoothly, the pipe body is required to have a connection characteristic that the pipe body can be connected with a small insertion force and a pull-out resistance characteristic that the pipe bodies do not easily come out after being connected once.

  As a method of connecting the tubular bodies, for example, in Patent Document 1, an annular seal piece that stands up in the axial direction and inclines toward the back in the insertion direction is provided on the inner surface of the receiving port (socket) of the receiving side tubular body. The structure which provides and inserts the insertion port of the insertion side tube body in this receptacle is disclosed. As shown in FIG. 1 and the like of this document, a plurality of the seal pieces are provided side by side in the tube axis direction, and the inner diameter thereof is slightly smaller than the outer diameter of the insertion opening.

  When the insertion port is inserted into the receiving port of the receiving side tube provided with the seal piece, the inner diameter side end portion of the seal piece and the insertion port come into contact with each other, as shown in FIG. The piece is deformed so as to fall in the insertion direction of the insertion slot. Along with this deformation, the inner diameter of the seal piece is increased, and the insertion port is inserted coaxially while being in contact with the seal piece.

  On the other hand, when a pulling force acts on the insertion side tube in a state in which the tubes are connected to each other, as shown in FIGS. 6A and 6B, the insertion direction (in FIG. The seal piece 9 that has fallen in the left direction is caused on the distal end side (right direction in the figure) of the receiving port 2 (see arrow s in the figure). Then, the raised seal piece 9 is in a state of being bitten between the inner surface of the receiving port 2 and the outer surface of the insertion port 4. By this biting, the force required for pulling out the insertion side tube body is greatly increased, and the effect of preventing the insertion side tube body from coming off is exhibited.

  The insertion port 4 has a tapered forward taper shape whose outer diameter decreases toward the tip of the insertion port 4 (see FIG. 6A), or a straight shape with a constant outer diameter in the axial direction. (See FIG. 6B) can be adopted as appropriate.

JP 59-180193 A

  When the forward taper 10 which expands the outer diameter of the insertion port 4 from the front end side to the back side is formed in the insertion port 4 like the pipe joint structure shown in Patent Document 1, the insertion amount is The larger the number, the greater the number of seal pieces 9 that come into contact with the insertion port 4 and the outer diameter of the insertion port 4 gradually increases, so that the contact resistance (contact force) between the insertion port 4 and the seal piece 9 gradually increases. When the insertion port 4 has a straight shape, the greater the amount of insertion, the greater the number of seal pieces 9 that come into contact with the insertion port 4, so that the contact resistance between the insertion port 4 and the seal piece 9 becomes less It grows in steps corresponding to the number. That is, in any case, the total contact resistance increases with the insertion, and the insertion of the insertion port 4 may not be smoothly performed.

  Then, this invention makes it a subject to make it possible to connect pipes easily, ensuring the retaining action of the pipes once connected.

  In order to solve the above problems, the present invention is provided with an annular seal piece standing in the axial direction on the inner surface of the receiving port of the receiving tube, and when the insertion port of the side tube is inserted into the receiving port, The seal piece is deformed so as to fall down in the insertion direction by contact with the insertion port, the inner diameter of the seal piece is increased, and the insertion port is inserted while the insertion side tube When a pulling force is applied to the body, a seal piece that falls into the back in the insertion direction is caused on the distal end side of the receptacle, and this seal piece is engaged between the inner surface of the receptacle and the outer surface of the insertion port. In a pipe joint structure in which the insertion side tube body is prevented from being pulled out, a reverse taper that reduces the outer diameter of the insertion port from the distal end side of the insertion port toward the back side. The structure which forms is adopted.

  When the reverse taper is formed in this way, the connection work between the tubular bodies can be performed smoothly. That is, when the insertion port has a reverse tapered shape, the number of seal pieces that come into contact with the insertion port increases as the amount of insertion increases, but the outer diameter of the insertion port gradually decreases as the insertion port is inserted. And the contact resistance between the seal pieces gradually decreases. For this reason, compared with the structure of patent document 1 of background art, the increase in the total contact resistance accompanying this insertion can be suppressed as much as possible. For this reason, insertion of an insertion slot can be performed smoothly.

  On the other hand, even when this reverse taper is formed, the retaining action of the pipes once connected is ensured. Compared with the configuration of Patent Document 1, the shape of the taper is different only in the forward taper and the reverse taper, and the contact force (pull-out force) between the reverse taper and the seal piece does not change so much as a total. is there.

  Thus, when it is set as a reverse taper, there also exists a merit which can exhibit a drop-preventing action rapidly. That is, the friction between the reverse taper and the seal piece acts in the direction in which the seal piece is raised (in the direction of the tube axis), compared with the forward taper and straight shape shown in FIGS. 6 (a) and 6 (b). This can be done more effectively. For this reason, the retaining action between the tubular bodies is exhibited more quickly and reliably.

  Furthermore, the tip of the seal piece (the barb portion) comes into contact with the edge portion of the reverse taper end portion, and this edge portion bites into the seal piece, thereby further increasing the force required for pulling out. For this reason, further improvement of the retaining action by reverse taper can be expected.

  The pipe joint structure shown in the above configuration is suitable for use in a fiber reinforced plastic (FRP) pipe.

  This FRP pipe is significantly lighter than cast iron pipes generally used for water pipes and the like, and is often used when laying electric cables and communication cables. In such an application, a large force is unlikely to act on the connecting portion between the tube bodies, and the simple structure in which both the tube bodies are simply connected via a seal piece as in the pipe joint structure according to the above configuration. However, this is because troubles are less likely to occur in terms of connection strength and water tightness. Also, the pipe joint can be made flexible by using a seal piece in the pipe joint. Even if the pipe joint is slightly bent and the pipe joint is slightly bent, the connection state is maintained. Can do.

  According to the present invention, an annular seal piece is provided on the inner surface of the receiving port of the receiving tube, and an insertion port of the inserting tube having a reverse taper at the tip is inserted into the receiving port. When inserting the insertion port, the contact resistance between the seal piece and the insertion port gradually becomes smaller with the insertion compared to the insertion port formed with a tapered forward taper. Work can be done smoothly.

  On the other hand, when a pulling force acts on the insertion side tube body, a predetermined contact force acts between the reverse taper and the seal piece, thereby exhibiting a retaining action. Furthermore, the reverse taper allows the seal piece that has fallen in the insertion direction to be quickly inserted during insertion, and can be interposed between the inner surface of the receiving port and the outer surface of the insertion port. The

Sectional drawing which shows one Embodiment of the pipe joint structure which concerns on this invention The partial cross-sectional perspective view which shows one Embodiment of this invention Sectional drawing which shows the state which connected the tubular bodies in one Embodiment of this invention The principal part sectional drawing in one Embodiment of this invention is shown, (a) is the state which is inserting the insertion port into a receptacle, (b) is the state which inserted the insertion port to the back in the receptacle Main part sectional drawing which shows the effect | action of the insertion port which formed the reverse taper with respect to a seal piece It is principal part sectional drawing which shows the effect | action of the insertion port with respect to the seal piece in a prior art, Comprising: When (a) forms a forward taper, (b) does not form a taper

  One embodiment of the pipe joint structure according to the present invention is shown in FIGS. This pipe joint structure is of a type in which the insertion port 4 of the insertion side tube 3 is inserted into and connected to the reception port 2 of the reception side tube 1. The receiving side tubular body 1 and the insertion side tubular body 3 are both FRP pipes using fiber reinforced plastic (FRP).

  As shown in FIGS. 1 and 2, the insertion port 4 of the insertion side tube 3 has a tip taper 5 that expands the outer diameter of the insertion port 4 from the most distal end of the insertion port 4 toward the back side. In addition to being formed, a reverse taper 6 is formed continuously from the distal end taper 5 to reduce the outer diameter of the insertion opening 4 from the distal end side to the back side of the insertion opening 4. The end edge of the reverse taper 6 on the back side of the insertion opening also serves as a push-in position display line, and a predetermined retaining action is exhibited by inserting the insertion opening into the push-in position display line. The boundary between the tip taper 5 and the reverse taper 6 is an edge portion 8 where the outer diameter of the insertion port 4 turns from expansion to reduction.

  An annular seal member 7 made of a rubber material is provided on the inner surface of the receiving port 2 of the receiving side tube 1. On the inner periphery of the seal member 7, there are four annular seal pieces 9a, 9b, 9c, 9d that stand up in the axial direction and whose tip end in the axial direction inclines toward the back in the insertion direction. The seal member 7 is integrally formed.

  The seal piece (first seal piece 9 a) formed on the most front side of the receiving port 2 has an inner diameter slightly smaller than the maximum outer diameter of the distal end portion of the insertion port 4 of the insertion side tube 3. The mouth 4 is smoothly guided to the receptacle 2. The seal pieces (second seal piece 9b and third seal piece 9c) formed second and third from the front side of the receiving port 2 have the same shape, and the cross-sectional outer shape of the tip portion is substantially M-shaped. I am doing. The tip portion protrudes further to the inner diameter side than the first seal piece 9a, and ensures the watertightness between the tube bodies 1 and 3. The seal piece (fourth seal piece 9d) formed on the innermost side of the receiving port 2 has a larger inclination angle toward the back side than the second and third seal pieces 9b and 9c, and the shape thereof is also different. Between each seal piece 9a-9d, it has a circumferential groove shape, and when the insertion port 4 is inserted, the seal pieces 9b, 9c fall into this circumferential groove.

  As shown in FIG. 3, when the insertion port 4 of the insertion side tube 3 is inserted into the reception port 2 of the reception side tube 1, the seal pieces 9 b to 9 d that are in contact with the tip of the insertion port 4 are inserted. It falls into the back of the direction. Along with this fall, the inner diameter of the seal pieces 9b to 9d (distance between the shaft center and the tip of the seal pieces 9b to 9d) is increased, and the insertion port 4 is inserted coaxially while being in contact with the seal pieces 9b to 9d. It is. At the time of this insertion, since the number of seal pieces 9b to 9d that come into contact with the insertion opening 4 gradually increases as the insertion amount increases, it seems that the resistance to insertion increases.

However, since the reverse taper 6 is formed in the insertion opening 4, when attention is paid to a specific circumferential groove (or the seal pieces 9 b to 9 d), as the insertion amount increases, the inner surface of the receiving opening 2 and the insertion opening are increased. 4 is widened (g ₁ <g ₂ when comparing the length of the arrow g ₁ in FIG. 4A and the arrow g ₂ in FIG. 4B). The contact resistance between the outer surface of the opening 4 and the seal pieces 9b to 9d gradually decreases as the amount of insertion increases. As described above, the contact resistance of the seal pieces 9b to 9d gradually decreases as the insertion port 4 is inserted, so that the total contact resistance does not increase so much and the insertion of the insertion port 4 is not hindered.

  On the other hand, when a pulling force is applied to the insertion side tube 3 once inserted into the receiving side tube 1, as shown in FIG. 5, the reverse side taper 6 of the insertion port 4 causes the tube to fall back in the insertion direction. A seal piece (seal piece 9d is illustrated) is caused on the tip side of the receiving port 2 (see arrow s in the figure). The seal piece 9 d thus caused is in a state of being bitten between the inner surface of the receiving port 2 and the outer surface of the insertion port 4. By this biting, the force required for pulling out the insertion side tube 3 is greatly increased, and the retaining action is exhibited.

  It is preferable that a force acts on the seal piece 9d so as to approach the rising direction of the seal piece 9d, that is, the tube axis. When the insertion port 4 is pulled out, the reverse taper 6 causes a frictional force to act on the seal piece 9d in the pulling direction and in the tube axis direction (see arrow f in the figure). The piece 9d is caused smoothly. In FIG. 5, the taper angle of the reverse taper 6 is exaggerated from the actual one so that the operation of the reverse taper 6 can be easily understood visually.

  Further, when the sealing pieces 9b to 9d come into contact with the edge portion 8 when the insertion-side tube body 3 is pulled out, the edge portion 8 bites into the rubber sealing pieces 9b to 9d and the force required for pulling out further increases. In addition, it can be expected to further improve the retaining action.

  The shape and the number of the seal pieces 9a to 9d employed in the above embodiment can be appropriately changed as long as the connecting function and the watertight function of the pipe bodies 1 and 3 can be exhibited.

  Also about the shape of the reverse taper 6 contact | abutted to this seal piece 9a-9d, it can change suitably. In addition to the embodiment in which the tip taper 5 and the reverse taper 6 are continuously formed as in the above-described embodiment, the reverse taper 6 is formed from the tip end to the back side of the insertion opening 4 without forming the tip taper 5. It can be set as the aspect which forms only. Moreover, the aspect which a taper angle changes in the middle of an axial center direction can also be employ | adopted instead of reducing in diameter by the fixed taper angle toward the back | inner side from the front end side of the insertion port 4.

  In the above embodiment, the pipe joint structure is applied to the FRP pipe. However, the use of the pipe joint structure is not limited to the FRP pipe, and cast iron may be used depending on the use or nominal diameter. The present invention can be applied to various tube bodies such as tubes.

  In the above embodiment, the receiving tube 1 and the receiving port 2 are integrated. However, the receiving port 2 is separated from another member (for example, a “socket” that can be freely attached to and detached from the receiving tube). It can also be set as the aspect which carried out.

DESCRIPTION OF SYMBOLS 1 Reception side pipe body 2 Reception port 3 Insertion side pipe body 4 Insertion opening 5 Tip taper 6 Reverse taper 7 Seal member 8 Edge part 9 (9a, 9b, 9c, 9d) Seal piece 10 Forward taper

Claims (2)

An annular seal piece (9) is provided on the inner surface of the receiving port (2) of the receiving side tube (1), and is erected in the axial direction. The insertion port (4) of the inserting side tube (3) is inserted into the receiving port (2). ), The seal piece (9) is deformed so as to fall down in the insertion direction by contact with the insertion port (4), and the inner diameter of the seal piece (9) is increased. While the diameter of the insertion port (4) is inserted, when a pulling force is applied to the insertion side tube (3), the seal piece (9) that falls down in the insertion direction is the receiving port. (2) The seal piece (9) is caused on the distal end side, and the seal piece (9) is engaged between the inner surface of the receiving port (2) and the insertion port (4) and the insertion side tube. In the pipe joint structure in which the body (3) is prevented from coming off,
A pipe joint characterized in that a reverse taper (6) for reducing the outer diameter of the insertion port (4) is formed in the insertion port (4) from the distal end side to the back side of the insertion port (4). Construction.   A fiber reinforced plastic pipe employing the pipe joint structure according to claim 1.

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