JP4933978B2 - Mandrel seal - Google Patents

Description

  The present invention relates to a mandrel seal part of a hydraulic expansion device.

  Currently, a roller expansion method, a hydraulic expansion method, a seal welding method, an explosion tube expansion method, and the like are used as a method for joining tube materials such as heat exchangers and condensers to a tube sheet. Among them, the hydraulic expansion method that directly expands using a hydraulic pressure of several thousand atmospheres is used in many fields because it can work in a clean environment with accurate and strong expansion using the energy of hydraulic pressure. . In the roller tube expansion method, peeling (flaking) may occur on the inner surface of the tube due to rolling pressure, but in the liquid pressure tube expansion method, uniform contact pressure is applied to the inner surface of the tube to expand the tube, so the contact pressure is managed accurately. It is possible to expand the pipe with high reliability.

  As shown in FIG. 7, the mandrel seal portion of the liquid pressure expansion device is an aqua tube type in which the discharge portion L2 of the high pressure liquid supply portion of the mandrel body 102 is sealed with an aqua tube 103 to prevent leakage of high pressure liquid. Yes (see Patent Document 1).

  Such an aqua tube type mandrel seal portion 101 includes a mandrel main body 102 into which high pressure liquid is introduced, an aqua tube 103 that encloses the high pressure liquid, and a rubber backup ring 104 that holds the front and rear of the aqua tube 103. , A metal fixing ring 105 and an expansion ring 106 which form a wedge shape and constitute an expansion mechanism. Further, on the outer periphery of the mandrel main body 102, on the rear side of the aqua tube 103, there is a collar 107 that accommodates the protruding portion of the tube material from the tube plate and positions the aqua tube 103 (the expanded portion). ing.

  Then, along the axial direction of the expansion ring 106, a slit 106 a formed from the end surface on the aqua tube 103 side toward the opposite side of the aqua tube 103 is formed in the expansion ring 106.

With this configuration, when a high-pressure liquid is supplied, the aqua tube 103 is expanded (expanded diameter) by the hydraulic pressure, and the pipe material is expanded. Then, after the tube expansion molding, the aqua tube 103 is elastically reduced in diameter so that the mandrel body 102 can be easily pulled out from the tube material.
Japanese Utility Model Publication No. 58-49146

However, since the contact surface between the backup ring 104 and the fixing ring 105 is formed flat in the conventional mandrel seal portion 101, the backup is compressed and deformed by being pressed along with the expansion of the aqua tube 103 during tube expansion molding. A part of the ring 104 was easy to protrude from the outer peripheral surface of the fixed ring 105. Therefore, the consumption of the backup ring 104 was severe.
Further, the backup ring 104 that protrudes from the outer peripheral surface of the fixing ring 105 gets over the fixing ring 105 and enters the slit portion of the expansion ring 106 (between the fixing ring 105 and the expansion ring 106) to be bitten off. There was a case.

  In addition, a part of the backup ring 104 that has been compressed and deformed may enter between the mandrel body 102 and the fixing ring 105 during tube expansion molding. As described above, if a part of the backup ring 104 enters between the mandrel main body 102 and the fixing ring 105, the backup ring 104 is damaged and the fixing ring 105 is removed when each part of the mandrel seal portion 101 is replaced. There was a problem that it became difficult. Therefore, at the time of manufacturing the fixing ring 105, it is necessary to perform high-precision processing that minimizes the gap between the inner diameter of the fixing ring 105 and the outer diameter of the mandrel body 102, thereby reducing the manufacturing cost of the hydraulic expansion device. It was an obstacle.

  In order to solve the above-described problems, an object of the present invention is to provide a mandrel seal portion of a hydraulic pressure expansion device that can improve the durability of the device and improve the workability during component replacement. .

  In order to solve the above-mentioned problem, the invention according to claim 1 is a mandrel in which a high-pressure liquid supplied from a main body through a tube expansion tool portion is sealed and the tube material is expanded from the inner surface while being inserted into the tube material. A mandrel body connected to the tube expansion tool part and introduced with the high-pressure liquid; a cylindrical elastic body that is attached to an outer periphery of the mandrel body and encloses the high-pressure liquid and expands the diameter; A backup ring attached to the outer periphery of the mandrel body along at least one end surface of the cylindrical elastic body; and an outer periphery of the mandrel body along an end surface of the backup ring opposite to the cylindrical elastic body And a fixing ring having a wedge-shaped portion whose outer diameter is reduced toward the end surface opposite to the backup ring, and the wedge-shaped portion of the fixing ring A tapered recess that is attached to the outer peripheral portion of the mandrel body along the end surface of the mandrel and has an inner diameter that is expanded toward the fixing ring so as to fit the wedge-shaped portion. An annular expansion ring configured such that the wedge-shaped portion is pressed against the tapered concave portion by the liquid pressure of the liquid and is expandable in the radial direction, and the backup ring side end portion of the fixing ring The inner diameter of the mandrel is enlarged so that a housing space is formed between the outer surface of the mandrel body and the inner surface of the fixing ring.

  Since the mandrel seal part of such a hydraulic pressure expansion device has a housing space formed in the fixing ring, the backup ring loaded with a pressing force during the tube expansion molding enters the housing space, so that the outer surface of the fixing ring The protrusion is suppressed. As a result, the life of the backup ring can be improved.

  In addition, since the accommodation space is formed in the fixing ring, the thinned fixing ring exhibits a function as an elastic body such as a disc spring. Therefore, it becomes possible to suppress elastic deformation in the direction of positively expanding the diameter by the pressing force of the cylindrical elastic body transmitted through the backup ring, and to prevent the backup ring from protruding to the outer peripheral surface of the fixing ring. . In addition, the elastic force of the fixing ring makes it possible to quickly return the backup ring to its original state during decompression. Therefore, it is possible to prevent damage to the backup ring and improve the life of the mandrel seal portion.

  Furthermore, by forming an accommodation space in which the backup ring can enter in the fixing ring in advance, it is possible to prevent a part of the backup ring from entering the inside of the fixing ring and the mandrel body.

  “High pressure” means a pressure required for tube expansion molding, and generally means a pressure of several thousand atmospheres, although it depends on the size and shape of the tube. The liquid used as the “high pressure liquid” is not limited, and water or oil is generally used.

  The invention according to claim 2 is the mandrel seal part according to claim 1, characterized in that a resin ring mounted on an outer peripheral part of the mandrel body is disposed in the accommodation space. .

  According to such a mandrel seal portion, the resin ring is compressed and deformed by the pressing force of the backup ring at the time of pipe expansion molding, and the diameter is reduced in the inner diameter direction of the resin ring, so that the backup ring is interposed between the fixing ring and the mandrel body. Prevent entry.

  The invention according to claim 3 is the mandrel seal part according to claim 1 or 2, wherein the wedge-shaped part has a section length of 60% or more with respect to the total length of the fixing ring. It is characterized by.

  According to such a mandrel seal part, the deformation area of the backup ring can be reduced, and the life of the mandrel seal part can be improved.

  According to the mandrel seal portion of the hydraulic expansion apparatus according to the present invention, it is possible to improve the durability of the apparatus and the workability at the time of component replacement.

Preferred embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
In the drawings to be referred to, FIG. 1 is a perspective view for explaining the overall configuration of the hydraulic expansion device according to the present embodiment. FIG. 2 is a half sectional view showing the configuration of the mandrel seal portion according to this embodiment. 3A and 3B are schematic views showing the mandrel seal portion, the tube material, and the tube sheet, wherein FIG. 3A is a cross-sectional view showing a state before tube expansion molding in which the mandrel seal portion is inserted into the tube material, and FIG. 3B is a mandrel seal. It is sectional drawing which shows the condition at the time of pipe expansion molding by a part.

  As shown in FIG. 1, the mandrel seal portion 1 of the hydraulic expansion device 10 according to the present embodiment joins a tube plate and a tube material inserted into a tube hole formed in the tube plate via a high-pressure liquid. In the hydraulic pressure expanding device 10 to be inserted, the high pressure liquid supplied from the main body 11 through the tube expanding tool portion 12 is enclosed while being inserted into the tube material, and the tube material is expanded from the inner surface. The hydraulic pressure expansion device 10 includes a mandrel seal portion 1, a tube expansion tool portion 12 that injects high pressure liquid into the mandrel seal portion 1, and a main body portion 11 that supplies high pressure liquid to the tube expansion tool portion 12. Yes.

  The mandrel seal portion 1 is attached to the tube expansion tool portion 12, and high pressure liquid is supplied from the main body portion 11 through the high pressure tube 11a. Further, the tube expanding tool portion 12 and the main body portion 11 are connected by a control hydraulic tube 11b and a pressure reducing drainage tube 11c.

  The mandrel seal portion 1 is attached as an attachment of the hydraulic expansion device 10. The mandrel seal portion 1 is inserted into the pipe material W1 to be subjected to pipe expansion processing, encloses the high-pressure liquid to form a high-pressure chamber P, and the pipe material W1 is expanded and formed by the pressure of the high-pressure chamber P. And the tube sheet W2 are joined (see FIG. 3B). In the present embodiment, the pipe material W1 has a circular cross section, but the cross sectional shape of the pipe material W1 is not limited.

As shown in FIG. 2, the mandrel seal portion 1 is connected to a tube expansion tool portion 12 (see FIG. 1), is attached to a mandrel body 2 into which high-pressure liquid is introduced, and an outer peripheral portion of the mandrel body 2. An aqua tube (cylindrical elastic body) 3 that forms a high-pressure chamber P (see FIG. 3B) by enclosing high-pressure liquid between a certain pipe W1 (see FIG. 3) and the mandrel body 2; It is configured.
Further, the mandrel seal portion 1 includes a back-up ring 4 and a fixed ring 5 disposed so as to hold the back-up ring 4 in the axial direction of the mandrel body 2 in the axial direction of the mandrel body 2 of the aqua tube 3. And an expansion ring 6. The expansion ring 6 is formed with a slit 6a along the axial direction.

  Further, on the outer periphery of the mandrel main body 2 and on the rear side of the aqua tube 3, a collar (progress allowance housing member) 7 for adjusting the tube expansion position is mounted.

  As shown in FIG. 2, the mandrel body 2 is a member formed in a round bar shape, and communicates from the end surface on the tube expansion tool portion 12 (FIG. 1) side (the end surface on the right side in this figure) to the aqua tube 3. A flow path L1 for the high-pressure liquid is formed along the axial direction to the central portion of the mandrel main body 2, and a communication hole L2 that communicates from the central portion of the mandrel main body 2 to the aqua tube 3 is provided. In the present embodiment, one communication hole L2 is provided. However, the number of communication holes L2 is not limited, and for example, four communication holes L2 may be provided radially.

  A head adapter 2a connected to the tube expansion tool portion 12 (FIG. 1) is attached to the rear side (right side in the figure) of the mandrel body 2. On the other hand, a nut 2b is screwed to the front side (left side in the figure) of the mandrel body 2.

  The aqua tube 3 is a bag-like member made of, for example, nylon, urethane rubber, soft vinyl chloride, nitrile rubber or fluororubber, and is provided on the outer peripheral surface of the mandrel body 2 as shown in FIG. ing. When the high pressure liquid is introduced into the flow path L1 of the mandrel body 2 and discharged from the communication hole L2, the aqua tube 3 is filled with the high pressure liquid to form a high pressure chamber P (see FIG. 3B). ).

  As shown in FIG. 2, the aqua tube 3 according to this embodiment forms adhesive surfaces 3 a and 3 a by folding both ends of a plate-like elastic material, and these adhesive surfaces 3 a and 3 a are formed on the outer peripheral surface of the mandrel body 2. It is formed in a tube shape by adhering in an annular shape along. It is assumed that the aqua tube 3 has adhesive surfaces 3a and 3a that are completely in close contact with the mandrel body 2 so that the high-pressure liquid enclosed therein does not leak out. In the present embodiment, the aqua tube 3 is formed using a plate-like elastic material. However, the material constituting the aqua tube 3 is not limited, and for example, a cylindrical elastic material is used. An annular ring may be formed by bonding both ends, and this may be disposed on the outer periphery of the mandrel body 2. Moreover, the material which comprises the aqua tube 3 will not be limited to the said thing, if it is a material with strong elasticity and little abrasion.

  As shown in FIG. 2, the backup ring 4 is disposed along the front and rear end faces of the aqua tube 3, has a ring-like disk shape, and is made of an elastic member such as urethane rubber. The backup ring 4 follows the deformation of the aqua tube 3 at the time of tube expansion molding, and assists the force of the aqua tube 3 returning to its original shape after the tube expansion molding.

  As shown in FIGS. 2 and 3, the fixing ring 5 is a metal member having a ring-like disk shape. The fixing ring 5 is formed with a wedge-shaped portion 5 a whose outer diameter is reduced toward the end surface in contact with the expansion ring 6. The wedge-shaped portion 5a is adapted to a tapered shape portion 6b of the expansion ring 6 described later, and the fixing ring 5 and the expansion ring 6 are engaged with each other in a state where the tapered shape portion 6b and the wedge-shaped portion 5a are in close contact with each other. .

  In the present embodiment, the length of the fixing ring 5 in the front-rear direction is formed to 2.6 mm, the length of the wedge-shaped portion 5a in the front-rear direction is 2.1 mm, and the planar portion is formed to 0.5 mm. Needless to say, the shape dimension of the fixing ring 5 is not limited to the above, but the length of the wedge-shaped portion 5a in the front-rear direction is preferably 60% of the total length of the fixing ring 5 in the front-rear direction. Above, more preferably 80% or more.

  Further, as shown in FIG. 3A, the fixing ring 5 is formed with an accommodation portion (accommodation space) 5 b in which a part of the backup ring 4 can enter at the end of the backup ring 4 side during tube expansion molding. . The accommodating part 5b is formed by expanding the inner diameter of the fixed ring 5, and an internal resin ring 8 is disposed inside the accommodating part 5b.

  The accommodating part 5b is formed by forming a taper on the inner surface of the end part on the backup ring 4 side of the fixing ring 5 and expanding the diameter. The inner resin ring 8 is attached to the outer periphery of the mandrel body 2 at the corner of the accommodating portion 5b on the side of the expansion ring 6.

  The internal resin ring 8 is a resin elastic body having a ring-like disk shape. Although the material which comprises the internal resin ring 8 is not limited, In this embodiment, it comprises with high intensity engineering plastics. Examples of high-strength engineering plastics include polyimide, polycarbonate, polyacetal, polybutylene terephthalate, and modified polyphenylene ether.

As shown in FIG. 2, the expansion ring 6 has a cylindrical circular shape.
As shown in FIGS. 2 and 3A, the expansion ring 6 has a tapered portion 6b whose inner diameter is increased toward the end surface in contact with the fixing ring 5 on the end surface on the fixing ring 5 side. Yes. Further, the expansion ring 6 has a slit portion 6a so that the wedge-shaped portion 5a of the fixing ring 5 presses the tapered portion 6b by the hydraulic pressure of the high-pressure liquid so that the expansion ring 6 can expand in the radial direction. Is formed.

  In the present embodiment, the pressing force and stroke in the diameter expansion direction of the expansion ring 6 are adjusted by appropriately setting the inclination angle formed by the wedge-shaped portion 5a of the fixing ring 5 and the taper-shaped portion 6b of the expansion ring 6. can do. For this reason, optimal tube expansion molding conditions can be obtained by setting this inclination angle in accordance with various conditions such as the size of the tube material W1 that is a workpiece and a gap (expansion stroke) with the tube sheet W2.

The collar 7 arranges the aqua tube 3 at a predetermined position (expanded portion) with respect to the tube plate W2 by making the length of the protrusion from the tube plate W2 of the tube material W1 at the time of tube expansion molding constant, It is a member that makes it possible to perform pipe expansion molding with high quality.
That is, the mandrel seal portion 1 is inserted into the space 7a of a certain length formed between the collar 7 and the expansion ring 6 with the tip portion (protrusion) protruding from the tube plate W2 of the tube material W1 being inserted. It pushes in and makes the length of the allowance of the pipe material W1 constant.
The configuration of the collar 7 is not limited as long as the length of the allowance for the tube material can be made constant.

  Subsequently, the operation of the mandrel seal portion 1 according to the present embodiment will be described with reference to FIGS. 3 (a) and 3 (b).

In the state where the mandrel seal portion 1 is inserted into the tube material W1 such as a heat exchanger to be expanded (FIG. 3 (a)), the high-pressure liquid is supplied to the mandrel body 2 and the expansion operation is started.
When high pressure liquid is injected into the aqua tube 3 (high pressure chamber P) from the mandrel body 2 (flow path L1, communication hole L2), the aqua tube 3 expands in the radial direction (expands diameter), thereby pressing the pipe material W1. Works.

  In this way, the tubular material W1 is expanded from the inside by the hydraulic pressure energy of the high pressure chamber P that is gradually increased in pressure, and the outer surface of the tubular material W1 comes into contact with the inner surface of the hole in the tube plate W2. When the pressure in the high pressure chamber P is further increased, the tube material W1 is pressed against the tube plate W2, and the hole of the tube plate W2 is elastically deformed. At this time, the tube material W1 is deformed to the plastic region, and after releasing the pressure of the high-pressure chamber P, a contact residual stress is generated between the tube material W1 and the tube plate W2, and strong fixation is performed.

  On the other hand, when high-pressure liquid is injected from the mandrel body 2 (flow path L1, communication hole L2) into the aqua tube 3 (high pressure chamber P), the aqua tube 3 is moved back and forth as the aqua tube 3 expands in the radial direction. A pressing force acts on the front and rear backup rings 4 by expanding in the direction. When a pressing force is applied to the backup ring 4, as shown in FIG. 3B, the backup ring 4 is difficult to expand in the radial direction because part of the backup ring 4 enters the housing portion 5 b of the fixing ring 5. 4 is prevented from protruding to the outer peripheral surface of the fixing ring 5.

  Further, the backup ring 4 that has entered the housing portion 5 b biases the internal resin ring 8 with a pressing force. The inner resin ring 8 is compressed and deformed by the pressing force acting via the backup ring 4, and the outer surface is expanded and the inner surface is decreased. As described above, the inner resin ring 8 is reduced in the inner diameter direction so that the gap between the mandrel body 2 and the fixing ring 5 is sealed, and the backup ring 4 enters between the mandrel body 2 and the fixing ring 5. To prevent that.

Further, when a pressing force in the front-rear direction acts on the fixing ring 5 through the backup ring 4, the fixing ring 5 is elastically deformed in the direction of the expansion ring 6, and the backup ring 4 protrudes from the outer peripheral surface of the fixing ring 5. Suppress.
Further, when the pressing force acts on the fixing ring 5, the wedge-shaped portion 5 a enters the tapered shape portion 6 b and the expansion ring 6 is expanded in diameter. Thereby, the pipe material W1 is pipe-expanded.

  When the high pressure chamber P is depressurized after completion of the tube expansion molding, the aqua tube 3 is contracted by the restoring force. When the aqua tube 3 is contracted, the backup ring 4 quickly returns to the original state by the elastic force of the fixing ring 5 together with its restoring force.

  Since the aqua tube 3 returns to the original state when the high pressure chamber P is depressurized, the mandrel seal portion 1 can be easily extracted from the pipe material W1.

  As described above, according to the mandrel seal portion 1 of the hydraulic pressure expansion device 10 of the present embodiment, the backup ring 4 is prevented from entering the outer peripheral surface and the inner peripheral surface of the fixing ring 5 at the time of tube expansion molding. It is difficult to wear out, and the life of the mandrel seal portion 1 can be prolonged.

  Further, the ratio of the fixed ring 5 to the total length of the wedge-shaped portion 5a is larger than that of the conventional fixed ring, and the parallel portion is formed smaller, so that the deformation region of the backup ring 4 (the backup ring 4 Since the amount of protrusion) can be reduced, it is possible to suppress wear of the backup ring 4.

  Further, since the internal resin ring 8 is arranged in the housing portion 5b, the backup ring 4 is prevented from being caught between the fixing ring 5 and the mandrel body 2. Therefore, the backup ring 4 is prevented from being damaged and the fixing ring 5 and the like cannot be removed, and the workability at the time of exchanging the parts of the mandrel seal portion 1 can be improved.

The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments and examples, and can be implemented with appropriate modifications.
For example, in the above-described embodiment, the internal resin ring is arranged in the accommodating portion. However, the internal resin ring may be arranged as necessary and can be omitted.

  In the above embodiment, the backup ring, the fixing ring, and the expansion ring are arranged before and after the aqua tube. However, the same effect can be obtained by using the aqua tube as an O-ring. It is good also as a structure arrange | positioned only to one side.

Moreover, in the said embodiment, it is good also as a structure which suppresses consumption of an aqua tube by arrange | positioning an aqua cover to the outer periphery of an aqua tube.
Further, the tube expansion length (the thickness of the tube plate) of the tube material is not limited and may be set as appropriate.

  Next, the result of a demonstration experiment conducted for verifying the effect of the mandrel seal portion according to the present invention is shown.

(1) Effect of receiving portion (accommodating space) of fixing ring First, each mandrel seal portion is repeatedly subjected to tube expansion molding using a mandrel seal portion provided with fixing rings having different shape receiving portions. By comparing the lifespans of these, the effect of the fixing ring in which the accommodating portion was formed was verified. FIG. 4 is a schematic diagram showing the shape of the fixing ring of each case used in this demonstration experiment, where (a) shows case 1, (b) shows case 2, and (c) shows a comparative example. FIG. 5 is a graph showing the results of this demonstration experiment.

  In this demonstration experiment, as shown in FIG. 4 (a), a trapezoidal accommodating portion 51b having a taper angle θ1 that expands by 45 ° toward the end surface is formed at the end portion on the backup ring 4 side. As shown in FIG. 4B, the mandrel seal portion A1 (case 1) using the ring 51 and the trapezoidal-shaped accommodating portion 52b whose taper angle θ2 expands by 65 ° toward the end surface are used as a backup. About the mandrel seal part A2 (case 2) using the fixing ring 52 formed at the ring 4 side end part, the lifetime of each mandrel seal part A1, A2 was measured. Further, as a comparative example, as shown in FIG. 4 (c), a mandrel seal portion A3 using a conventional fixing ring 53 in which no housing portion is formed was also verified.

  In this demonstration experiment, the fixing ring has a maximum outer diameter of 20.9 mm, a minimum inner diameter of 16.1 mm, an overall thickness (full length) B of about 2.6 mm, and a taper-shaped portion thickness (length) B2 of about It unified to the thing of 1.9 mm, the pipe expansion pressure was 214 Mpa, and the pipe expansion time was 2 second.

In the case 1, as the fixing ring 51, the depth b (length in the front-rear direction) of the accommodating portion is 0.6 mm, the inner diameter is about 18.0 mm to 19.2 mm, and the member thickness of the backup ring side end surface A h of about 0.9 mm was used. In the case 2, as the fixing ring 52, the depth (length in the front-rear direction) b of the accommodating portion is 0.6 mm, the inner diameter is about 18.0 mm to 20.5 mm, and the member thickness of the end surface on the backup ring side is The h used was about 0.2 mm.
FIG. 5 shows the verification result.

As shown in FIG. 5, according to the case 1, the life of the mandrel seal part A1 can be expanded about 1000 times, and the mandrel seal part A2 of the case 2 can be increased about 300 times. It has been demonstrated that On the other hand, the conventional mandrel seal portion A3 (comparative example) that does not include the accommodating portion has a result of about 200 times.
Therefore, it has been demonstrated that the life of the mandrel seal portion is improved by forming the accommodating portion in the fixing ring.

(2) Effect of the length of the wedge-shaped part Next, in the demonstration experiment, which was conducted to increase the life of the mandrel seal part by increasing the ratio of the length of the wedge-shaped part to the entire length of the fixing ring. Results are shown.

  Table 1 shows the shape dimensions and verification results of the fixing ring used in this demonstration experiment.

  In this demonstration experiment, the length B1 in the front-rear direction of the parallel portion (portion having a constant outer diameter) is shortened relative to the total length of the wedge-shaped portion, as compared with Comparative Example 1 formed with a conventional general shape. The lifespan of the mandrel seal portion was compared when using the case 3 and the case 4 having a large ratio (wedge-shaped portion length B2 / total length B) (see FIG. 4C).

As case 3, as shown in Table 1, a fixing ring in which the ratio of the wedge-shaped portion to the total length of the fixing ring was 81% was used. Further, in case 4, a fixing ring in which the ratio of the wedge-shaped portion to the total length of the fixing ring is 81% and a receiving portion is formed at the end portion on the backup ring side is used. Further, as a comparative example, in Comparative Example 2, a fixing ring in which the ratio of the wedge-shaped portion to the fixing ring was 59%, and in Comparative Example 3, a fixing ring in which the ratio of the wedge-shaped portion to the fixing ring was 35% was used.
Here, the tube expansion pressure in this demonstration experiment was 214 MPa, and the tube expansion time was 2 seconds.

As shown in Table 1, the number of tube expansions of the case 3 and the case 4 with a wedge-shaped portion of 81% is 291 times and 1021 times, respectively, 71 times of the comparative example 2 having the shape of a conventional general fixing ring. It was proved to be greatly improved compared to
On the other hand, as in Comparative Example 3, when the thickness (full length) of the fixing ring is increased and the ratio of the wedge-shaped portion is decreased, the number of tube expansions is 11 times, which proves that consumption is accelerated.

  Therefore, if the length of the wedge-shaped portion of the fixing ring is set to 60% or more, more preferably 80% or more, with respect to the total length of the fixing ring, it is possible to measure the longevity of the mandrel seal portion. .

(3) Effect by resin ring Next, the result of having verified about the effect of the lifetime improvement of the mandrel seal part by a fixing ring being provided with a resin ring is shown. Here, FIG. 6 is a cross-sectional view showing a part of the mandrel seal portion used in this demonstration experiment, where (a) shows a case where a conventional fixing ring is used (case 5) and (b) shows a resin ring. Is shown (case 6).

In this demonstration experiment, as shown in FIGS. 6A and 6B, the fixing rings 54 and 55 arranged in the mandrel seal portions B1 and B2 are arranged with the resin ring 8 arranged and not arranged. Utilizing each, the tube expansion molding was repeated, and the number of tube expansion moldings until the mandrel seal portions B1 and B2 were damaged was measured.
Here, the tube expansion pressure in this demonstration experiment was 214 MPa, and the tube expansion time was 2 seconds.

As shown in FIG. 6 (a), as the case 5, a fixing ring 54 in which a resin ring is not disposed and the backup ring 4 side is formed flat (perpendicular to the axial direction of the mandrel body 2) is used. As shown in FIG. 6B, the case 6 has the same outer shape as the fixing ring 54 of the case 5, and is fixed with the resin ring 8 disposed on the inner surface side of the end portion on the backup ring 4 side. A ring 55 was used.
The fixing rings 54 and 55 have a maximum outer diameter of 20.9 mm, a minimum inner diameter of 16.1 mm, an overall thickness (full length) of about 2.6 mm, and a taper-shaped portion having a thickness (length) of about 1. .9 mm was used.

  Table 2 shows the results of the demonstration experiment.

  As shown in Table 2, the life of the mandrel seal part of the case 5 where the resin ring is not arranged is 21 times, whereas the life of the mandrel seal part of the case 6 where the resin ring is arranged is 71 times. there were. Therefore, it has been proved that the life of the mandrel seal part is significantly improved by arranging the resin ring on the back-up ring side inner surface part of the fixing ring.

It is a perspective view for demonstrating the whole structure of the hydraulic expansion apparatus which concerns on suitable embodiment of this invention. It is a half sectional view showing the composition of the mandrel seal part concerning the preferred embodiment of the present invention. It is a schematic diagram showing a mandrel seal part, a pipe material and a tube sheet according to a preferred embodiment of the present invention, (a) is a cross-sectional view showing the state before the tube expansion molding in which the mandrel seal part is inserted into the pipe material, (B) is sectional drawing which shows the condition at the time of pipe expansion molding by a mandrel seal part. It is a schematic diagram which shows the shape of the fixing ring of each case used in the demonstration experiment conducted in order to demonstrate the effect of the mandrel seal part which concerns on this invention, Comprising: (a) is case 1 and (b) is case 2 (C) is sectional drawing of a comparative example. It is a graph which shows the result of the demonstration experiment using the fixing ring shown in FIG. 4, and the vertical axis | shaft shows the lifetime of a mandrel seal part, and the taper inclination angle of the area | region part of a fixing ring is shown on a horizontal axis. It is sectional drawing which shows a part of mandrel seal part used in the verification experiment about the effect of the lifetime improvement of the mandrel seal part by arrange | positioning a resin ring to a fixing ring, (a) uses the conventional fixing ring In this case, (b) shows a case where a resin ring is provided. It is a half sectional view showing the composition of the conventional mandrel seal part.

Explanation of symbols

1 Mandrel seal 2 Mandrel body 3 Aqua tube (cylindrical elastic body)
4 Backup ring 5 Fixing ring 5a Wedge-shaped part 5b Storage part (accommodation space)
6 Expansion ring 6b Tapered part 8 Internal resin ring (resin ring)
DESCRIPTION OF SYMBOLS 10 Liquid pressure expansion apparatus 11 Main-body part 12 Tube expansion tool part P High pressure chamber W1 Pipe material W2 Tube sheet

Claims (3)

A mandrel seal part that encloses the high-pressure liquid supplied from the main body part via the pipe expansion tool part in a state of being inserted into the pipe material, and performs pipe expansion molding of the pipe material from the inner surface,
A mandrel body connected to the tube expansion tool portion and into which the high pressure liquid is introduced;
A cylindrical elastic body that is attached to the outer periphery of the mandrel body and encloses the high-pressure liquid to expand the diameter;
A backup ring attached to the outer periphery of the mandrel body along at least one end surface of the cylindrical elastic body;
A wedge shape that is mounted on the outer peripheral portion of the mandrel body along the opposite end surface of the cylindrical elastic body of the backup ring, and whose outer diameter is reduced toward the end surface side opposite to the backup ring. A fixing ring having a portion;
A tapered shape that is attached to the outer peripheral portion of the mandrel body along the end surface of the fixing ring on the wedge-shaped portion side, and whose inner diameter is expanded toward the fixing ring side so as to fit the wedge-shaped portion. And an annular expansion ring configured such that the wedge-shaped portion is pressed against the tapered shape portion by the hydraulic pressure of the high-pressure liquid and is expandable in the radial direction.
The mandrel seal is characterized in that an inner diameter of a backup ring side end portion of the fixing ring is expanded so that an accommodation space is formed between an outer surface of the mandrel body and an inner surface of the fixing ring. Department.   The mandrel seal part according to claim 1, wherein a resin ring attached to an outer peripheral part of the mandrel body is disposed in the housing space. The mandrel seal part according to claim 1 or 2, wherein a section length of the wedge-shaped part is 60% or more with respect to a total length of the fixing ring.

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