Pipe expansion device

Abstract

To connect a metal pipe to a pipe joint in which a structure for connecting the metal pipe is simplified.SOLUTION: A pipe expansion device 300 includes a head part 320, a compression rod 322, and an annular elastic body 324. The head part 320 includes a passage formed therein. The compression rod 322 penetrates through the passage formed in the head part 320. The compression rod 322 penetrating through the passage penetrates through the annular elastic body 324. The annular elastic body 324 contacts with the head part 320. The annular elastic body 324 contacts with a tip of an entering part of the head part 320. The elastic body contact part of the compression rod 322 contacts with a rear surface of a surface, which contacts with the head part 320, of the annular elastic body 324.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a tube expanding device. [Background technology]

[0002] Patent Document 1 discloses a tube expansion device. This tube expansion device is an apparatus having a tube expansion head, a tube expansion ring, a guide ring, a pressure rod, a tube expansion rubber, and a rubber presser. The tube expansion head has an insertion bore and a first tapered portion. A thin-walled stainless steel tube is fitted into the insertion bore. The first tapered portion is formed in the front of the insertion bore. The first tapered portion is inclined so that the diameter of the front is expanded. The tube expansion ring has a fitting hole and a second tapered portion. The fitting hole is detachably fixed to the front of the tube expansion head. A thin-walled stainless steel tube is fitted into the fitting hole. The second tapered portion is continuous with the first tapered portion. The second tapered portion is inclined so that the diameter of the front is reduced. The guide ring is positioned radially inside the insertion bore. The thin-walled stainless steel tube is fitted onto the guide ring. A pressure rod is inserted into the tube expansion head. The rear end of the pressure rod is connected to a pressure device. The tube expansion rubber is fitted onto the pressure rod in front of the guide ring. The rubber presser portion is formed on the pressure rod in front of the tube expansion rubber. This tube expansion device forms an insertion bore and a guide ring so that, when the thin-walled stainless steel pipe is inserted, there is a fixed gap between the thin-walled stainless steel pipe and the insertion bore and the guide ring, respectively. With the tube expansion device disclosed in Patent Document 1, the tip of the steel pipe can be easily fitted into the main body bore of the fitting. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-120029 Summary of the Invention [Problem to be solved by the invention]

[0004] The tube expansion device disclosed in Patent Document 1 has the problem that it can only connect metal tubes to fittings that have a tube expansion head, and cannot connect metal tubes to fittings that do not have a tube expansion head.

[0005] An object of the present invention is to enable connection of a metal pipe to a pipe joint having a simplified structure for connecting the metal pipe. [Means for solving the problem]

[0006] The tube expanding device of the present invention will be described with reference to the drawings. Note that the reference numerals used in this section are intended to facilitate understanding of the invention, and are not intended to limit the scope of the invention to that shown in the drawings.

[0007] To achieve the above-mentioned object, according to one aspect of the present invention, a tube expanding device 300 includes a head portion 320, a pressure rod 322, and an annular elastic body 324. The head portion 320 has a passage formed therein. The pressure rod 322 passes through the passage formed in the head portion 320. The pressure rod 322, which passes through the passage, passes through the annular elastic body 324. The annular elastic body 324 contacts the head portion 320. The pressure rod 322 has a passage penetrating portion 350 and an elastic body contacting portion 352. The passage penetrating portion 350 passes through a passage formed in the head portion 320. The passage penetrating portion 350 faces the inner circumferential surface of the annular elastic body 324. The elastic body contacting portion 352 is connected to the passage penetrating portion 350. The elastic body contacting portion 352 contacts the back surface of the surface of the annular elastic body 324 that contacts the head portion 320. The head portion 320 has an entry portion 340 and a fitting connection portion 342. The entry portion 340 is for entering the interior of the pipe fitting 420 from one end of the pipe fitting 420. The entry portion 340 is also for entering the interior of the metal pipe 200 that has entered the other end of the pipe fitting 420. A passage is formed in the entry portion 340. The fitting connection portion 342 is for connecting the pipe fitting 420 to the entry portion 340 when the entry portion 340 has entered the interior of the pipe fitting 420. An annular elastic body 324 contacts the tip of the entry portion 340 of the head portion 320.

[0008] The tip of the entry portion 340, which enters the interior of the pipe fitting 420 from one end thereof, and the elastic body contact portion 352 of the pressure rod 322, which passes through a passage formed in the entry portion 340, compress the annular elastic body 324. The annular elastic body 324, whose outer diameter increases due to this compression, increases the outer diameter of the metal pipe 200. When the outer diameter of the metal pipe 200 increases, the portion of the metal pipe 200 with the increased outer diameter is pressed against the inner circumferential surface of the pipe fitting 420. When this portion is pressed against the inner circumferential surface of the pipe fitting 420, the metal pipe 200 is connected to the pipe fitting 420. As a result, the metal pipe 200 can be connected to the pipe fitting 420, which has a simplified configuration for connecting the metal pipe 200.

[0009] Furthermore, it is desirable that the above-described entry portion 340 has a cylindrical entry main body 360 and an engaging protrusion 362. The engaging protrusion 362 is provided on the outer periphery of the entry main body 360. In this case, it is desirable that the fitting connection portion 342 has a cylindrical connection main body 380, a one-end engaging portion 382, ​​and an other-end threaded portion 384. The one-end engaging portion 382 is provided at one end of the connection main body 380. The one-end engaging portion 382 engages with the engaging protrusion 362. The other-end threaded portion 384 is provided at the other end of the connection main body 380. The other-end threaded portion 384 engages with the male thread 62 provided on the pipe fitting 420.

[0010] The other-end threaded portion 384 engages with the male thread 62 provided on the pipe fitting 420. The one-end engaging portion 382 engages with the engaging protrusion 362 of the entry portion 340. This causes the pipe fitting 420 to be connected to the head portion 320 via the other-end threaded portion 384. Because the pipe fitting 420 is connected to the head portion 320, the possibility of the pipe fitting 420 becoming misaligned when the outer diameter of the metal pipe 200 increases is reduced.

[0011] Alternatively, it is desirable that the aforementioned insertion body portion 360 has a cylindrical tip forming portion 400 and a cylindrical large diameter forming portion 402. The tip forming portion 400 forms the tip of the insertion portion 340. The large diameter forming portion 402 is continuous with the tip forming portion 400. The large diameter forming portion 402 has a larger outer diameter than the tip forming portion 400. In this case, the engagement protrusion 362 is provided on the outer periphery of the large diameter forming portion 402 of the insertion body portion 360.

[0012] Because the outer diameter of the large diameter forming portion 402 is larger than the outer diameter of the tip forming portion 400, the tip forming portion 400 can enter the interior of the metal pipe 200, whose inner diameter is larger than the outer diameter of the tip forming portion 400. The large diameter forming portion 402 can enter the interior of the pipe fitting 420, whose inner diameter is larger than the outer diameter of the large diameter forming portion 402. This can prevent, to a certain extent, the formation of a significant gap between the interior of the pipe fitting 420 and the entry main body portion 360. Reducing the formation of such a gap reduces the possibility of the pipe fitting 420 becoming misaligned when the outer diameter of the metal pipe 200 increases. [Effects of the Invention]

[0013] According to the present invention, a metal pipe can be connected to a pipe joint having a simplified configuration for connecting the metal pipe. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is an external view of a tube expanding device according to an embodiment of the present invention. [Figure 2] FIG. 2 is an external view of a head unit according to an embodiment of the present invention. [Figure 3] 1 is an external view of a pressure rod according to an embodiment of the present invention. FIG. [Figure 4] 1 is an external view of a pipe joint connected to a metal pipe by a pipe expanding device according to an embodiment of the present invention. [Figure 5] FIG. 1 is a side view of a fitting body according to an embodiment of the present invention. [Figure 6] 1 is a diagram showing a state in which a metal pipe has entered a pipe joint in an embodiment of the present invention. [Figure 7]10 is a view showing a state after an elastic contact portion according to an embodiment of the present invention has penetrated a pipe joint and a metal pipe. FIG. [Figure 8] 10 is a diagram showing a state in which an elastic contact portion according to an embodiment of the present invention pushes open a metal pipe from the inside. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the same components are designated by the same reference numerals. Their names and functions are the same. Therefore, detailed descriptions thereof will not be repeated.

[0016] [Configuration of the tube expansion device] Fig. 1 is an external view of a tube expanding device 300 according to this embodiment. Fig. 1 shows the tube expanding device 300 in a state in which a tube fitting 420 according to this embodiment and a metal tube 200 are connected. In Fig. 1, the objects shown are shown in a partially cut-out state. The configuration of the tube expanding device 300 according to this embodiment will be described below with reference to Fig. 1.

[0017] The tube expanding device 300 according to this embodiment includes a head portion 320, a pressure rod 322, and an annular elastic body 324.

[0018] A passage is formed inside the head portion 320. The pressure rod 322 passes through the passage formed in the head portion 320. The pressure rod 322 passing through the passage also passes through the annular elastic body 324. The annular elastic body 324 is sandwiched between the head portion 320 and the pressure rod 322. The outer diameter of the annular elastic body 324 is compressed by the head portion 320 and the pressure rod 322, increasing the outer diameter of the metal tube 200.

[0019] Fig. 2 is an external view of the head unit 320 according to this embodiment. In Fig. 2, some of the objects shown are cut away. The configuration of the head unit 320 according to this embodiment will be described below with reference to Fig. 2.

[0020] In this embodiment, the head portion 320 has an entrance portion 340 , a joint connection portion 342 , a compression force support portion 344 , and a holding portion 346 .

[0021] The entry portion 340 is for entering the interior of the pipe fitting 420 from one end thereof. The entry portion 340 is also for entering the interior of the metal pipe 200 that has entered the other end of the pipe fitting 420. A passage is formed in the entry portion 340. The fitting connection portion 342 connects the pipe fitting 420 to the entry portion 340. In this embodiment, the entry portion 340 penetrates the fitting connection portion 342. The compression force support portion 344 penetrates the fitting connection portion 342. The compression force support portion 344 is connected to the entry main body portion 360. When the entry main body portion 360 receives a force due to compression of the annular elastic body 324, the compression force support portion 344 supports the force. The holding portion 346 holds the entry portion 340 via the compression force support portion 344. The holding portion 346 also holds the pressure rod 322.

[0022] In this embodiment, the insertion portion 340 has a cylindrical insertion main body portion 360 and an engaging protrusion portion 362. The engaging protrusion portion 362 is provided on the outer periphery of the insertion main body portion 360. In this embodiment, the engaging protrusion portion 362 has an annular shape.

[0023] In this embodiment, the entry body portion 360 has a cylindrical tip forming portion 400 and a cylindrical large diameter forming portion 402. The tip forming portion 400 forms the tip of the entry portion 340. The large diameter forming portion 402 is continuous with the tip forming portion 400. The large diameter forming portion 402 has a larger outer diameter than the tip forming portion 400. In this embodiment, the above-described engaging protrusion 362 is provided on the outer periphery of the large diameter forming portion 402, which is part of the outer periphery of the entry body portion 360.

[0024] In this embodiment, the fitting connection portion 342 has a cylindrical connection main body portion 380, a one-end engaging portion 382, ​​and an other-end threaded portion 384. The one-end engaging portion 382 is provided at one end of the connection main body portion 380. The one-end engaging portion 382 engages with the engaging protrusion portion 362. The other-end threaded portion 384 is provided on the inner periphery of the other end of the connection main body portion 380. As a result, the other-end threaded portion 384 forms a female thread. The other-end threaded portion 384 engages with the male thread 62 provided on the pipe fitting 420.

[0025] Fig. 3 is an external view of the pressure rod 322 according to this embodiment. In Fig. 3, some parts shown are cut away. Hereinafter, the configuration of the pressure rod 322 according to this embodiment will be described with reference to Fig. 3.

[0026] In this embodiment, the pressure rod 322 has a passage penetrating portion 350 , an elastic body contact portion 352 , and a penetrating end connecting portion 354 .

[0027] The passage penetrating portion 350 penetrates a passage formed in the head portion 320. As a result, the passage penetrating portion 350 penetrates the entrance portion 340, the compression force support portion 344, and the retaining portion 346. The passage penetrating portion 350 faces the inner peripheral surface of the annular elastic body 324. The passage penetrating portion 350 is retained by the retaining portion 346.

[0028] The elastic body contact portion 352 is continuous with the passage penetrating portion 350. The elastic body contact portion 352 is in contact with the surface of the annular elastic body 324 that is opposite to the surface that is in contact with the head portion 320.

[0029] The penetrating end connecting portion 354 is connected to one end of the passage penetrating portion 350 that has penetrated the entrance portion 340 (in this case, the end on the holding portion 346 side). The penetrating end connecting portion 354 is also held by the holding portion 346 together with the passage penetrating portion 350.

[0030] [Pipe fitting explanation] Fig. 4 is an external view of a pipe fitting 420 to be connected to a metal pipe 200 by a pipe expanding device 300 according to this embodiment. A portion of the pipe fitting 420 is cut away in Fig. 4. The configuration of the pipe fitting 420 will be described below with reference to Fig. 4.

[0031] As shown in FIG. 4, the pipe fitting 420 of this embodiment has a cylindrical fitting body 440, a pair of annular seal members 42, 42, a nut 44, an annular accommodating portion 46, a plurality of engaging protrusions 48, an entry direction correcting tube 50, and a spacer 52.

[0032] The joint body 440 is a member that forms the main body of the pipe joint 420. A metal pipe (not shown) enters the inside of the joint body 440 from one end (the end where the nut 44 is connected). The metal pipe 200 described above enters the inside of the joint body 440 from the other end (the end where the nut 44 is not connected).

[0033] The pair of seals 42, 42 are both disposed within the joint body 440. One of the pair of seals 42, 42 seals between the inner peripheral surface of the joint body 440 and the outer peripheral surface of the metal pipe (not shown). The other of the pair of seals 42, 42 seals between the inner peripheral surface of the joint body 440 and the outer peripheral surface of the metal pipe 200.

[0034] The nut 44 is connected to one end of the joint body 440. A metal tube (not shown) passes through the nut 44.

[0035] One end of the joint body 440 passes through the accommodation portion 46. The engaging protrusion 48 protrudes from the accommodation portion 46. The engaging protrusion 48 is for engaging with the nut 44.

[0036] The entry direction correcting tube 50 is housed within the joint body 440. The entry direction correcting tube 50 corrects the entry direction of a metal pipe (not shown) that attempts to enter the joint body 440 from one end thereof.

[0037] One end of the joint body 440 passes through the spacer 52. The spacer 52 is disposed so as to contact the receiving portion 46.

[0038] [Fitting body configuration] Fig. 5 is a side view of a joint body 440 according to this embodiment. In Fig. 5, the illustrated objects are shown with portions cut away. Hereinafter, the configuration of the joint body 440 according to this embodiment will be described with reference to Fig. 5.

[0039] The joint body 440 according to this embodiment has a joint flow path forming portion 460 , a male thread 62 , and a displacement prevention portion 464 .

[0040] The joint flow path forming portion 460 forms a flow path through which water or other fluids pass.

[0041] The male thread 62 is disposed on the outer periphery of one end of the joint flow path forming portion 460. The male thread 62 becomes the threaded portion of the joint main body 440 according to this embodiment.

[0042] In the present embodiment, the above-described accommodating portion 46 is disposed at a position adjacent to the root of the male thread 62 when viewed from the tip of the male thread 62. The above-described multiple engaging protrusions 48 protrude along the central axis 580 of the joint flow path forming portion 460. In the present embodiment, the central axis of the male thread 62 coincides with the central axis 580 of the joint flow path forming portion 460. As a result, the above-described multiple engaging protrusions 48 protrude from the accommodating portion 46 along the central axis of the male thread 62.

[0043] As described above, in this embodiment, the central axis of the male thread 62 coincides with the central axis 580 of the joint flow path forming portion 460. In this embodiment, the accommodating portion 46 is arranged in a state where rotation around the central axis 580 of the joint flow path forming portion 460 in the joint body 440 is restricted. As a result, the accommodating portion 46 is arranged in a state where rotation around the central axis of the male thread 62 is restricted.

[0044] The slippage prevention portion 464 according to this embodiment is an annular portion that protrudes from the outer periphery of the joint flow-channel forming portion 460. The slippage prevention portion 464 prevents the accommodating portion 46 from slipping in the circumferential direction around the central axis 580 of the joint flow-channel forming portion 460, and therefore the central axis of the male thread 62. In doing so, the slippage prevention portion 464 allows the accommodating portion 46 to move inward when viewed from the tip of the male thread 62.

[0045] In this embodiment, the slippage prevention portion 464 has an exposed recess (not shown). The exposed recess is arranged on the outer periphery of the slippage prevention portion 464. The exposed recess is arranged so as to be exposed. The exposed recess is recessed. The exposed recess penetrates in the direction of the central axis 580 of the joint flow path forming portion 460. An anti-rotation protrusion (not shown) of the accommodating portion 46 fits into the exposed recess. By fitting the anti-rotation protrusion into the exposed recess that penetrates in the direction of the central axis 580 of the joint flow path forming portion 460, slippage of the accommodating portion 46 in the circumferential direction around the central axis of the male thread 62 is prevented. Movement of the accommodating portion 46 toward the back when viewed from the tip of the male thread 62 is possible.

[0046] In this embodiment, the joint flow path forming portion 460 has a communication passage forming portion 80, a one-end pipe end accommodating portion 82, a one-end seal material accommodating portion 84, an other-end pipe end accommodating portion 482, an other-end seal material accommodating portion 484, and an other-end pipe communication holding portion 500.

[0047] The one-end pipe end accommodating portion 82 is disposed adjacent to one end of the communicating passage forming portion 80. The one-end pipe end accommodating portion 82 accommodates one end of a metal pipe (not shown).

[0048] The one-end sealing material accommodating portion 84 is disposed adjacent to the one-end pipe end accommodating portion 82. One of the pair of sealing materials 42, 42 is accommodated in the one-end sealing material accommodating portion 84. One end of a metal pipe (not shown) passes through the one-end sealing material accommodating portion 84.

[0049] The other-end pipe end accommodating portion 482 is disposed adjacent to the other end of the communicating passage forming portion 80. In other words, the one-end pipe end accommodating portion 82 and the other-end pipe end accommodating portion 482 are disposed adjacent to each other with the communicating passage forming portion 80 in between. One end of the metal pipe 200 is accommodated in the other-end pipe end accommodating portion 482.

[0050] The other-end sealing material accommodating portion 484 is disposed adjacent to the other-end pipe end accommodating portion 482. The other of the pair of sealing materials 42, 42 is accommodated in the other-end sealing material accommodating portion 484. One end of the metal pipe 200 passes through the other-end sealing material accommodating portion 484.

[0051] The other-end-side pipe communication holding portion 500 holds the metal pipe 200 so that the inside of the metal pipe 200 is in communication with the inside of the joint body 440. In the case of this embodiment, the other-end-side pipe communication holding portion 500 accommodates a portion of the metal pipe 200 whose outer diameter has been expanded by the pipe expanding device 300 according to this embodiment.

[0052] In this embodiment, the central axis of the communicating passage forming portion 80, the central axis of the one-end pipe end accommodating portion 82, the central axis of the one-end sealant accommodating portion 84, the central axis of the other-end pipe end accommodating portion 482, the central axis of the other-end sealant accommodating portion 484, and the central axis of the other-end pipe communicating holding portion 500 all coincide with the central axis 580 of the joint flow passage forming portion 460. Therefore, the central axis of the male thread 62, the central axis of the one-end pipe end accommodating portion 82, the central axis of the one-end sealant accommodating portion 84, the central axis of the other-end pipe end accommodating portion 482, and the central axis of the other-end sealant accommodating portion 484 are common.

[0053] [Explanation of pipe expansion method] The method for expanding the metal pipe 200 according to this embodiment is as follows. First, the worker inserts the metal pipe 200 into the pipe fitting 420 from the other end side. Figure 6 is a diagram showing the state in which the metal pipe 200 has inserted into the pipe fitting 420. Next, the worker removes the nut 44 and the insertion direction correction tube 50 from the pipe fitting 420.

[0054] Next, the worker inserts the tube expanding device 300 according to this embodiment from one end side of the pipe fitting 420. As a result, the annular elastic body 324 and the insertion main body portion 360 enter the pipe fitting 420. The elastic body contact portion 352 penetrates the pipe fitting 420 and the metal pipe 200. Figure 7 is a diagram showing the situation after the elastic body contact portion 352 has penetrated the pipe fitting 420 and the metal pipe 200.

[0055] At this time, the tip forming section 400 of the entering main body section 360 enters the interior of the metal pipe 200. The large diameter forming section 402 of the entering main body section 360, which has a larger outer diameter than the tip forming section 400, enters the interior of the pipe fitting 420 near the one-end pipe end accommodating section 82. As is clear from Figure 7, the gap between the inner peripheral surface of the pipe fitting 420 and the outer peripheral surface of the entering main body section 360 near the one-end pipe end accommodating section 82 is quite small.

[0056] When the tube expansion device 300 of this embodiment enters from one end side of the tube fitting 420, the worker adjusts the positions of the tube fitting 420 and the metal tube 200 so that the annular elastic body 324 is positioned inside the metal tube 200 at a position corresponding to the inner circumference of the sealing material 42 of the tube fitting 420.

[0057] Once the positions of the pipe fitting 420 and the metal pipe 200 have been adjusted, the worker engages the female thread formed by the other-end thread portion 384 of the fitting connection portion 342 with the male thread 62 of the pipe fitting 420. This connects the pipe fitting 420 to the entry portion 340.

[0058] Next, the worker applies pressure to the passage-penetrating portion 350 and the elastic body contact portion 352 using a hydraulic pump (not shown). This pressure causes the passage-penetrating portion 350 and the elastic body contact portion 352 to move toward the position of the retaining portion 346. As this movement occurs, the elastic body contact portion 352 applies force to the annular elastic body 324. Because the annular elastic body 324 is in contact with the entry portion 340, the annular elastic body 324 is compressed by the force applied by the elastic body contact portion 352. The outer diameter of the compressed annular elastic body 324 increases. As a result, the metal pipe 200 is expanded from the inside. FIG. 8 is a diagram showing the state in which the elastic body contact portion 352 expands the metal pipe 200 from the inside.

[0059] When the metal pipe 200 has been sufficiently expanded, the worker stops applying pressure to the passage-penetrating portion 350 and the elastic body contact portion 352. As a result, compression of the annular elastic body 324 also stops. The outer diameter of the annular elastic body 324 for which compression has stopped returns to its original diameter. When the outer diameter of the annular elastic body 324 has returned to its original diameter, the worker removes the pipe fitting 420 and the metal pipe 200 from the pipe expanding device 300 according to this embodiment. This completes the pipe expanding method according to this embodiment.

[0060] [Explanation of Effects According to This Embodiment] As described above, the tube expanding device 300 according to this embodiment makes it possible to connect the metal tube 200 to the tube fitting 420 having a simplified configuration for connecting the metal tube 200.

[0061] Furthermore, in the case of the tube expanding device 300 according to this embodiment, the possibility of the tube joint 420 being displaced when the outer diameter of the metal tube 200 increases is reduced.

[0062] [Variations] The embodiments disclosed herein are examples in all respects. The scope of the present invention is not limited to the above-described embodiments. Of course, various design modifications may be made to the above-described embodiments without departing from the spirit of the present invention.

[0063] For example, the configuration of the entry body 360 is not limited to that described above. [Explanation of symbols]

[0064] 42...Sealing material 44...Nut 46...Storage section 48…Engagement convex portion 50…Entry direction correction tube 52...Spacer 62...Male thread 80…Communication path forming part 82...One end pipe end housing portion 84...One end side sealing material storage section 200…Metal tube 300...Tube expansion device 320...Head section 322...Pressure rod 324...Annular elastic body 340…Entry section 342...Joint connection part 344...Compression force support part 346...Holding part 350...Passageway 352...Elastic body contact part 354...Through end connection part 360…Entry main body part 362...Engagement protrusion 380...Connection body 382...One end engaging part 384...Threaded portion on the other end 400...Tip forming part 402...Large diameter forming section 420...Pipe fittings 440...Joint body 460...Joint flow path forming portion 464...Slip prevention part 482... Other end pipe end housing 484...Other end side sealing material storage section 500...Other end pipe communication holding portion 580…Central axis

Claims

1. a head portion having a passage formed therein; a pressure rod passing through the passage formed in the head portion; a ring-shaped elastic body through which the pressure rod passing through the passage passes and which is in contact with the head portion, The pressure rod is a passage-through portion that passes through the passage formed in the head portion and faces an inner peripheral surface of the annular elastic body; a tube expanding device having an elastic body contact portion connected to the passage penetration portion and contacting a back surface of a surface of the annular elastic body that contacts the head portion, The head portion is an entry portion in which the passage is formed, the entry portion being adapted to enter the interior of the pipe fitting from one end thereof and enter the interior of a metal pipe that has entered the other end of the pipe fitting; a fitting connection portion for connecting the pipe fitting to the entry portion when the entry portion enters the inside of the pipe fitting, A tube expanding device, characterized in that the annular elastic body contacts the tip of the entry portion of the head portion.

2. The entrance part is a cylindrical entry body; an engaging protrusion provided on the outer periphery of the entry body; The joint connection portion is a cylindrical connection body; a one-end engaging portion provided at one end of the connection body portion and engaging with the engaging protrusion; 2. A pipe expanding device according to claim 1, further comprising a threaded end portion provided at the other end of said connection body portion, said threaded end portion being adapted to engage with a threaded portion provided on said pipe joint.

3. The entry body portion is a cylindrical tip forming portion that forms the tip of the entry portion; a cylindrical large diameter forming portion that is connected to the tip forming portion and has an outer diameter larger than that of the tip forming portion, 3. The tube expanding device according to claim 2, wherein the engaging protrusion is provided on an outer periphery of the large diameter forming portion of the entry body portion.

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