JP2008080378A - Mandrel seal structure for hydraulic expansion equipment - Google Patents

Abstract

[PROBLEMS] To improve workability by reducing the size and weight and to ensure the durability of a seal portion.
A mandrel seal structure of a hydraulic pressure expansion molding apparatus having a mandrel seal portion for enlarging and molding an ultrahigh pressure liquid, the mandrel seal portion being attached to an outer peripheral portion of a mandrel 1a. An enclosing means (2) to be formed, and an annular movable ring member 4 disposed on at least one side of the ultrahigh pressure chamber so as to hold the enclosing means in the axial direction of the mandrel 1a. The member 4 includes a fixing ring 42 having a wedge-shaped portion 42a, and a tapered concave portion 41a whose inner diameter is increased toward the end face so as to fit the wedge-shaped portion 42a, and is a radially expandable slide. An expansion ring 41 provided with a split portion 41b, and the slit portion 41d includes a shaft of the expansion ring 41 extending from one end surface to the other end surface from the outer peripheral surface to the inner peripheral surface of the expansion ring 41. Along a direction crossing the direction to form the slitting plane.
[Selection] Figure 2

Description

  The present invention relates to a mandrel seal structure of a hydraulic tube forming apparatus, and more particularly to a mandrel seal structure of a hydraulic tube forming apparatus that improves the durability of a seal portion.

  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 tubes such as heat exchangers and condensers to a tube plate. Among them, the hydraulic expansion method, which expands directly using a fluid pressure of several thousand atmospheres, is capable of working in a clean environment with accurate and strong expansion using the energy of hydraulic pressure, and is used in many fields. . In the roller tube expansion method, peeling (flaking) may occur on the inner diameter of the tube due to rolling pressure, but in the liquid pressure tube expansion method, uniform pressure is applied to the inner surface of the tube to expand the tube, so the contact pressure is managed accurately. Can be expanded with high reliability.

Conventionally, as a mandrel seal structure of a hydraulic pressure expanding device, for example, an expansion ring provided with a slit is known. This type of mandrel seal structure 100 will be described with reference to FIGS.
FIG. 8A is a half sectional view showing a conventional mandrel seal structure, FIG. 8B is a sectional view showing the configuration of the expansion ring in FIG. 8A, FIG. 8C is a side view thereof, and FIG. Sectional drawing which shows the structure of a division | segmentation type expansion ring, (e) is the side view. Fig.9 (a) is principal part sectional drawing for demonstrating the effect | action at the time of pipe expansion, (b) is the elements on larger scale of (a).

As shown in FIG. 8A, this type of mandrel seal structure 100 includes a mandrel 100 a into which an ultrahigh pressure liquid is introduced, an O-ring 120 that encloses the ultrahigh pressure liquid, and a backup ring that holds the O-ring 120. 130 and a wedge-shaped ring 142 and an expansion ring 141 that constitute an expansion mechanism.
In the expansion ring 141, as shown in FIG. 8B, a slit is formed from the end surface to the vicinity of the center portion along the axial direction of the expansion ring 141.

  With this configuration, when an ultra-high pressure liquid is supplied, the wedge-shaped portion 142a of the wedge-shaped ring 142 is expanded by the hydraulic pressure via the O-ring 120 and the backup ring 130 as shown in FIG. 9B. By moving in the axial direction so as to enter the tapered portion 141a of 141, the expansion ring 141 is expanded (expanded) in the radial direction, and tube expansion molding is performed. Then, after the tube expansion molding, the expansion ring 141 is elastically reduced in diameter so that the mandrel can be easily pulled out from the tube.

Further, the shape of the slit portion includes various types in addition to the shape shown in FIG. 8A. For example, there is one in which a slit is provided from each end face of the expansion ring 141 toward the center portion. (Patent Document 1).
Further, as shown in FIG. 8 (e), the expansion ring 150 is completely divided by a slit 150a, and a holding member 160 such as a rubber belt or a clip is provided on the outer peripheral surface, and elastically held by the urging force thereof. There are types.
JP-A-11-28539

However, in the conventional mandrel seal structure, when the diameter of the expansion ring 141 is increased, the gap formed in the slit portion 141b is also increased. When a fluid pressure of several thousand atmospheres is applied in this state, the backup ring 130 made of an elastic member such as urethane rubber is radial when pressed through the O-ring 120 as shown in FIG. 9B. May expand over the wedge-shaped ring 142 and further enter the slit 141b (see FIG. 8A) of the expansion ring 141 (in the direction of the arrow).
For this reason, there is a problem that the backup ring bites into the expansion ring slit 141b, causing damage to the backup ring and adversely affecting the service life.

  Further, since the expansion ring 141 shown in FIG. 8A needs to generate an elastic force in the return direction by the slit portion, the length in the axial direction is increased to ensure the elastic force in the radial direction. It was. For this reason, the length of the mandrel itself is increased, resulting in a problem that the apparatus becomes large and the workability deteriorates. On the other hand, the split type expansion ring shown in FIG. 8D has a problem that the configuration becomes complicated and the number of parts increases.

  Therefore, in order to solve the above-mentioned problems, the present invention provides a mandrel seal structure for a hydraulic expansion molding apparatus that improves the workability by reducing the size and weight with a simple configuration and ensuring the durability of the seal portion. The issue is to provide.

  In order to solve the above-mentioned problem, the invention according to claim 1 is directed to a mandrel seal portion that encloses an ultra-high pressure liquid with a workpiece and performs tube expansion molding, and a tube expansion tool that injects the ultra-high pressure liquid into the mandrel seal portion. And a mandrel seal structure in the mandrel seal part of the hydraulic pipe expansion molding device having a main body part for supplying the ultrahigh pressure liquid to the pipe expansion tool part, and the mandrel seal part is connected to the pipe expansion tool part. A mandrel connected to and introduced into the outer periphery of the mandrel, and an enclosing unit for enclosing the ultrahigh pressure liquid between the work and the mandrel to form an ultrahigh pressure chamber; An annular movable ring portion that is disposed on at least one side of the ultra-high pressure chamber so as to hold the sealing means in the axial direction of the mandrel and is externally fitted to the mandrel. The movable ring member includes a fixing ring having a wedge-shaped portion whose outer diameter is reduced toward the end surface side, and an inner diameter that expands toward the end surface side so as to fit the wedge-shaped portion. An expansion ring having a tapered recess having a diameter, and provided with a slit that can be expanded in the radial direction by the wedge-shaped portion being pressed by the tapered recess by the pressure of the ultra-high pressure liquid. The slit portion is formed with a slit surface along a direction intersecting the axial direction of the expansion ring from one end surface to the other end surface from the outer peripheral surface to the inner peripheral surface of the expansion ring. It is characterized by that.

  The “ultra-high pressure” means a pressure necessary for tube expansion molding, and generally means a pressure of several thousand atmospheres, although it depends on the size and shape of the tube.

Thus, in the present invention, the slit surface is formed along the direction intersecting the axial direction of the expansion ring from one end surface to the other end surface from the outer peripheral surface to the inner peripheral surface of the expansion ring. Thus, when the expansion ring is expanded (expanded) in the radial direction, no gap is formed in the slit portion.
That is, the expansion ring is expanded (expanded) in the radial direction by the pressure of the ultrahigh pressure liquid in a state where the tapered recess of the expansion ring is pressed against the wedge-shaped portion of the fixing ring. At this time, since the hydraulic pressure of the ultra-high pressure liquid acts on the expansion ring in the axial direction, the slit surfaces are pressed against each other and deformed so that there is no gap in the slit surface. .

  As a result, it is possible to prevent other seal members arranged around the movable ring member from being sandwiched or bitten by the slit portion and to avoid damage to the seal member. Accordingly, it is possible to prevent the life of the hydraulic expansion tube forming apparatus from being reduced due to damage to the seal member.

The invention according to claim 2 is the mandrel seal structure according to claim 1, wherein the slit portion is provided at one place in a circumferential direction of the expansion ring.
According to such a configuration, since the slit portion is provided in one place in the circumferential direction of the expansion ring, it is not separated even if the expansion ring is expanded, so there is no need to separately provide a holding member for the expansion ring, The configuration can be simplified by reducing the number of parts.
Also, when the expansion ring is expanded (expanded) in the radial direction while the taper-shaped recess of the expansion ring is pressed against the wedge-shaped portion of the fixing ring by the hydraulic pressure of the ultrahigh pressure liquid, the expansion ring is elastic. Elastic force (restoring force) due to deformation is generated. And since this restoring force acts in the circumferential direction (tangential direction) of the expansion ring, the axial length of the expansion ring can be shortened.

The invention according to claim 3 is the mandrel seal structure according to claim 1, wherein the slits are provided in at least two locations in the circumferential direction of the expansion ring, and are provided on the outer periphery of the expansion ring. Is characterized in that a holding member for biasing toward the center of the expansion ring is provided.
According to such a configuration, since the slits are provided in at least two locations in the circumferential direction of the expansion ring, the expansion ring can be radially expanded in the radial direction. And moldability (for example, roundness) can be improved.

The invention according to claim 4 is the mandrel seal structure according to any one of claims 1 to 3, wherein the enclosing means is a seal member fitted on the mandrel, and the seal member Is interposed between the workpiece and the mandrel so that the ultrahigh pressure liquid is sealed.
According to such a configuration, a sealing member such as an O-ring is fitted on the mandrel to form the ultrahigh pressure chamber between the work and the mandrel, so that the configuration is simple and the apparatus can be made compact.

The invention according to claim 5 is the mandrel seal structure according to claim 4, wherein the enclosing member is a bag-like rubber member.
According to such a configuration, since the enclosing member forming the ultrahigh pressure chamber is a bag-like rubber member, it is possible to prevent the ultrahigh pressure liquid from leaking to the outside, and the apparatus is easy to handle.

The invention according to claim 6 is the mandrel seal structure according to any one of claims 1 to 5, wherein a backup ring made of an elastic member is interposed between the sealing means and the movable ring member. The movable ring member has a diameter-enlarged recess having a tapered shape in which an expansion ring is disposed on the backup ring side, and the diameter of the expansion ring is increased toward the end surface side on the backup ring side end surface. It is characterized by providing.
According to such a configuration, the expansion ring can be evenly pressed toward the fixed ring side by deforming the backup ring so as to curve toward the expansion ring side following the shape of the diameter-enlarged recess having a tapered shape.

  According to the mandrel seal structure of the liquid pressure expansion molding apparatus according to the present invention, the mandrel seal of the liquid pressure expansion molding apparatus that has a simple configuration, is reduced in size and weight, improves workability, and ensures the durability of the seal portion. Structure can be provided.

A first embodiment 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 apparatus according to the first embodiment of the present invention, and FIG. 2 is a half sectional view showing the configuration of a mandrel seal portion. FIG. 3 is an exploded perspective view of the mandrel seal portion.

As shown in FIG. 1, the mandrel seal structure in the mandrel seal portion 10 of the liquid pressure tube forming apparatus 11 according to the first embodiment of the present invention is an ultrahigh pressure liquid between the pipe W1 (see FIG. 6) that is a workpiece. A mandrel seal part 10 for encapsulating and expanding a tube, a tube expansion tool part 12 for injecting an ultrahigh pressure liquid into the mandrel seal part 10, and a body part 13 for supplying the tube expansion tool part 12 with an ultrahigh pressure liquid. It is the mandrel seal structure 1 (refer FIG. 2) in the mandrel seal part 10 of the liquid pressure tube forming apparatus 11 which has.
The mandrel seal portion 10 is attached to the tube expansion tool portion 12, and an ultrahigh pressure liquid is supplied from the main body portion 13 through the ultrahigh pressure tube 13a. Further, the tube expansion tool portion 12 and the main body portion 13 are connected by a control hydraulic tube 13b and a pressure reducing drainage tube 13c.

  The mandrel seal part 10 is attached as an attachment of the hydraulic pressure expansion forming apparatus 11. The mandrel seal portion 10 is inserted into a tube W1 to be expanded, encloses an ultrahigh pressure liquid to form an ultrahigh pressure chamber P, and the tube W1 is expanded by the pressure of the ultrahigh pressure chamber P. And the tube sheet W2 are joined (see FIG. 6). In the mandrel seal portion 10, various sealing methods are used in accordance with tube expansion conditions such as tube material, dimensions, and tube expansion pressure.

The mandrel seal structure 1 in the mandrel seal portion 10 according to the first embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 2, the mandrel seal structure 1 is mounted on a mandrel 1a into which an ultrahigh pressure liquid is introduced, and an outer peripheral portion of the mandrel 1a, and an ultrahigh pressure liquid is passed between a pipe W1 as a workpiece and the mandrel 1a. An O-ring 2 and a backup ring 3, which are sealing means for forming an ultrahigh pressure chamber P (see FIG. 6), and the O-ring 2 and the backup ring 3 are arranged to be held in the axial direction of the mandrel 1a. An expansion ring 41 and a fixing ring 42 are provided. The extension ring 41 is formed with a slit portion 41b along a direction intersecting the axial direction.

Further, the ultrahigh pressure chamber P (see FIG. 6) is provided with a spacer 5 that adjusts the position of the sealing member such as the O-ring 2 and adjusts the axial length of the ultrahigh pressure chamber P.
A head adapter 1b connected to the tube expansion tool portion 12 (FIG. 1) and a collar 1c for adjusting the tube expansion position are mounted on the rear side (right side in the figure) of the mandrel 1a. On the other hand, a nut 1d is screwed on the front side (left side in the figure) of the mandrel 1a.

Here, in the first embodiment, as shown in FIG. 2, with respect to the axial direction of the mandrel 1a, as viewed from the ultrahigh pressure chamber P (FIG. 6), the O-ring 2, the backup ring 3, the expansion ring 41, Since the fixing ring 42 has a bilaterally symmetric configuration, the front side structural member of the mandrel 1a will be described in principle, and the description of the rear side structural member will be omitted.
Further, in the following description, with respect to the axial direction of the mandrel 1a, the direction farther to the front side or the rear side as viewed from the ultrahigh pressure chamber P (FIG. 6) is expressed as the outside, and the direction approaching the ultrahigh pressure chamber P side is expressed as the inner side. There is a case.

As shown in FIG. 2, the mandrel 1a has 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 ultrahigh pressure chamber P (FIG. 6). The flow path L1 is formed along the axial direction to the center of the mandrel 1a, and four communication holes L2 are provided to communicate radially from the center of the mandrel 1a to the ultrahigh pressure chamber P.
In the present embodiment, the number of communication holes L2 is four. However, the number of the communication holes L2 is not limited to this, and the number of communication holes L2 is the diameter of the mandrel 1a, the volume of the ultrahigh pressure chamber P, the tube expansion length, and the like. In consideration of the specifications, an optimal number of one or more is set.

The ultra-high pressure chamber P is formed between the inner peripheral surface of the pipe W1, which is a workpiece, the outer peripheral surface of the mandrel 1a, and the O-rings 2 arranged on both sides (see FIG. 6). It is held by the backup ring 3.
As shown in FIG. 3, the O-ring 2 is a rubber seal member having an O-shaped cross section. However, the O-ring 2 is not limited to this, and so-called U-packing or the like can also be used. The O-ring 2 is provided in order to ensure the initial sealing performance at the time when the liquid pressure is relatively low when the ultrahigh pressure liquid is introduced.

  The backup ring 3 has a ring-shaped disk shape and is made of an elastic member such as urethane rubber. The backup ring 3 is provided in order to ensure the sealing performance at the time when the hydraulic pressure during pipe expansion molding is high.

In the first embodiment, the backup ring 3 is provided to enhance the sealing performance. However, the sealing performance is not limited to this, and for example, a sealing performance such as a tube type (see FIG. 7) described later is separately provided. Can be ensured, the backup ring 3 is not necessarily provided.
Further, in the present embodiment, urethane rubber is used as the material of the backup ring 3, but is not limited to this, and in consideration of airtightness, expandability, durability, etc., rubber metal, hard rubber, Nylon resin, polyethylene resin, Teflon (registered trademark), other resin materials, and the like are appropriately selected.

Next, the configuration of the expansion ring 41 and the fixed ring 42 which are the movable ring members 4 will be described mainly with reference to FIG. 4A and 4B are views showing the configuration of the expansion ring, where FIG. 4A is a plan view, FIG. 4B is a cross-sectional view taken along line A-A in FIG. 4A, FIG. 4C is a perspective view, and FIG. It is a typical side view for demonstrating an effect | action.
As shown in FIG. 2, the expansion ring 41 and the fixing ring 42 are arranged on the inner side (side closer to the ultrahigh pressure chamber P), and the fixing ring 42 is outer (side far from the ultrahigh pressure chamber P). Is arranged.

  As shown in FIG. 4, the expansion ring 41 has a ring-shaped disk shape. The end surface of the expansion ring 41 on the side of the fixing ring 42 has a tapered recess 41a whose inner diameter is increased toward the end surface contacting the fixing ring 42 (see FIG. 2), and is tapered by the liquid pressure of the ultrahigh pressure liquid. The wedge-shaped part 42a (refer FIG. 2) of the fixing ring 42 is pressed by the shape recessed part 41a, and the slit part 41b is provided so that expansion is possible to radial direction.

Further, as shown in FIG. 2, the end surface on the backup ring 3 side of the expansion ring 41 is provided with a diameter-enlarged recess 41c having a taper shape whose diameter is increased toward the end surface.
With this configuration, the expansion ring 41 can be pressed evenly toward the fixed ring 42 by deforming the backup ring 3 so as to bend toward the expansion ring 41 according to the shape of the diameter-enlarged recess 41c having a tapered shape. it can.

  As shown in FIG. 4 (a), the slit portion 41b has one place in the circumferential direction of the expansion ring 41, from the outer peripheral surface to the inner peripheral surface, and as shown in FIG. 4 (b). A slit surface 41d (FIG. 4D) is formed from the rear end surface 41e to the front end surface 41f along a direction intersecting the axial direction CL of the expansion ring 41 in a side view. .

Here, another embodiment of the expansion ring according to the present invention will be described with reference to FIG. FIGS. 5A and 5B are views showing another embodiment of the expansion ring, in which FIG. 5A is a plan view, FIG. 5B is a sectional view taken along line BB in FIG. 5A, and FIG.
The expansion ring 41 ′ according to the present embodiment is provided with one split portion 41 b ′ and 41 b ′ at two locations in the circumferential direction of the expansion ring 41 ′. This is different from the expansion ring 41 provided with the split portion 41b. For this reason, the expansion ring 41 ′ in this embodiment is divided into a half ring 41 A ′ and a half ring 41 B ′.

A ring groove 41g ′ is formed on the outer peripheral portion of the expansion ring 41 ′ (see FIG. 5B), and a snap ring 41h ′ that urges the ring groove 41g ′ toward the center of the expansion ring 41 ′. It is fitted (see FIG. 5C).
With this configuration, by providing the snap ring 41h ′, when the diameter of the expansion ring 41 ′ is expanded so as to expand in the radial direction, a biasing force acts in the direction of reducing the diameter of the expansion ring 41 ′.

  As shown in FIG. 2, the fixing ring 42 has a ring-shaped disk shape, and is formed with a wedge-shaped portion 42 a whose outer diameter is reduced toward an end surface in contact with the expansion ring 41. And the taper-shaped recessed part 41a (refer FIG. 2) of the expansion ring 41 and the wedge-shaped part 42a of the fixing ring 42 fit, and are engaged in the closely_contact | adhered state.

  In addition, by appropriately setting the inclination angle θ formed by the tapered concave portion 41a of the expansion ring 41 and the wedge-shaped portion 42a of the fixing ring 42, the pressing force and stroke in the diameter expansion direction of the expansion ring 41 can be adjusted. . For this reason, optimal tube expansion molding conditions can be obtained by setting this inclination angle θ according to various conditions such as the size of the tube W1 that is a workpiece and the gap (expansion stroke) with the tube sheet W2. .

  As shown in FIG. 2, the spacer 5 has a cylindrical shape that is fitted on the outer peripheral surface of the mandrel 1a, and is disposed in the ultrahigh pressure chamber P (FIG. 6). In the spacer 5, a ring groove 5 a is formed on the inner peripheral surface of the spacer 5 in order to quickly fill the ultrahigh pressure chamber P with the ultrahigh pressure liquid introduced into the mandrel 1 a. And the through-hole 5b penetrated from this ring groove 5a to the outer peripheral surface of the spacer 5 is formed in radial direction, and an ultra-high pressure liquid is discharged to the ultra-high pressure chamber P from this through-hole 5b.

  Next, the operation of the mandrel seal structure 1 according to the first embodiment of the present invention will be described with reference to FIG. FIG. 6 is a cross-sectional view of an essential part showing a state at the time of tube expansion molding for explaining the operation of the mandrel seal structure 1 according to the first embodiment of the present invention.

  In the following description, as described above, since the O-ring 2, the backup ring 3, the expansion ring 41, and the fixing ring 42 are symmetric when viewed from the ultrahigh pressure chamber P, the front side of the mandrel 1a is arranged. The operation (action) of the structural member will be described, but the description of the rear structural member will be omitted because it is the same.

The mandrel seal portion 10 (FIG. 2) is inserted into a tube W1 such as a heat exchanger to be expanded, and an ultrahigh pressure liquid is supplied to the mandrel 1a to start the expansion operation.
When the ultrahigh pressure liquid is injected from the mandrel 1a into the ultrahigh pressure chamber P, the O-ring 2 is first deformed to seal the inner peripheral surface of the tube W1 and to the outside (the ultrahigh pressure chamber P) with respect to the axial direction of the mandrel 1a. The pressing force acts on the far side as viewed from the side. Thereafter, when the pressure inside the ultrahigh pressure chamber P is further increased, the backup ring 3 is compressed and deformed in the axial direction of the mandrel 1a, and is expanded in the radial direction, and the inner circumferential surface of the pipe W1 is deformed. Ensure sealing performance.

In this way, the pressure in the ultrahigh pressure chamber P that is gradually increased is transmitted to the expansion ring 41 via the O-ring 2 and the backup ring 3. When the expansion ring 41 is pressed outward in the axial direction of the mandrel 1a (the far side as viewed from the ultrahigh pressure chamber P) by the hydraulic pressure of the ultrahigh pressure liquid, the fixing ring 42 abuts against the nut 1d (FIG. 2). Therefore, the expansion ring 41 is expanded (expanded) in the radial direction in a state where the tapered concave portion 41a of the expansion ring 41 is pressed against the wedge-shaped portion 42a of the fixing ring 42.
At this time, since the hydraulic pressure of the ultrahigh pressure liquid acts on the expansion ring 41 in the axial direction, the slit surfaces 41d (see FIG. 4D) are pressed against each other and deformed by being pressed in the overlapping direction. A gap is not formed on the split surface 41d.

  Accordingly, the movable ring member 4 (FIG. 2), that is, the other seal member such as the backup ring 3 disposed around the expansion ring 41 and the fixed ring 42 is sandwiched or bitten by the slit portion 41b. It is possible to prevent this and to prevent damage to the seal member. Accordingly, it is possible to prevent the life of the hydraulic expansion tube forming apparatus from being reduced due to damage to the seal member.

In this way, the outer diameter of the tube W1 is expanded by the hydraulic energy of the ultrahigh pressure chamber P, and comes into contact with the tube plate hole. When the pressure in the extra-high pressure chamber P is further increased, the tube W1 is pressed against the tube plate W2, and the tube plate hole is elastically deformed. At this time, the tube W1 is deformed to the plastic region, and after releasing the pressure of the ultrahigh pressure chamber P, a contact residual stress is generated between the tube W1 and the tube plate W2, and strong fixation is performed.
When the ultra-high pressure chamber P is depressurized after the end of the pipe expansion molding, the pressing force that presses the expansion ring 41 against the fixing ring 42 is also released, so that the expansion ring 41 is reduced in diameter by the elastic restoring force of the expansion ring. Thus, the mandrel seal portion 10 can be easily extracted from the tube W1.

  Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 7 is a half sectional view showing a mandrel seal structure according to the second embodiment of the present invention. In the first embodiment described above, the O-ring 2 is used as the sealing means (O-ring type), but in the second embodiment, the tube 8 that is a bag-like rubber member is used as the sealing means. (Tube type).

  As shown in FIG. 7, the tube 8 as a seal body of the ultrahigh pressure liquid is provided on the outer peripheral surface of the mandrel 1a, and the ultrahigh pressure liquid is introduced into the flow path L1 of the mandrel 1a and is discharged from the communication hole L2. The high pressure liquid is configured to be enclosed in the tube 8. Therefore, since the ultra-high pressure liquid (water or oil is used) does not leak, there is no fear of contaminating the work environment, and insertion into the pipe W1 is easy.

In the case of the O-ring type according to the first embodiment, the configuration is simple and particularly effective for small-diameter pipes. In the case of the tube type according to the second embodiment, the sealing performance is high, and the pipe W1. Even if the tube plate W2 (see FIG. 6) has a large clearance, it can be widely applied.
In the O-ring type and the tube type, the components and operations other than the O-ring 2 (FIG. 2) and the tube 8 (FIG. 7) are basically the same and will not be described.

As mentioned above, although embodiment of this invention was described, this invention is not limited to above-described embodiment and Example, It can change suitably and can implement.
For example, in the first embodiment, the spacer 5 is disposed in the ultrahigh pressure chamber P. However, the present invention is not limited to this, and a configuration in which the spacer 5 is not provided may be employed.

  In the first embodiment, the expansion ring 41 ′ (FIG. 5) is provided with two slit portions 41b ′ at positions facing each other in the circumferential direction. However, the present invention is not limited to this. It is possible to provide four or more places.

  In the first embodiment, the wedge-shaped portion 42a of the fixing ring 42 is provided over the entire circumference of the fixing ring 42 and has a continuous cone shape. However, the present invention is not limited to this, and the circumferential direction is not limited thereto. These may be provided discontinuously at a plurality of locations.

  In the first embodiment, regarding the arrangement of the expansion ring 41 and the fixing ring 42, the expansion ring 41 is arranged on the inner side (side closer to the ultrahigh pressure chamber P), and the fixing ring 42 is arranged on the outer side (far from the ultrahigh pressure chamber P). However, the present invention is not limited to this, and the fixing ring 42 may be disposed on the inner side and the expansion ring 41 may be disposed on the outer side (the side far from the ultrahigh pressure chamber P).

  In the first embodiment, the movable ring member 4 constituted by the expansion ring 41 and the fixed ring 42 is arranged so as to be symmetrical on both sides of the ultrahigh pressure chamber P with respect to the axial direction of the mandrel 1a. It is not limited, and it is possible to arrange the movable ring member 4 only on one side and configure the other side with other types of expansion rings and elastic members, and various combinations are possible. .

It is a perspective view for demonstrating the whole structure of the hydraulic-tube expansion molding apparatus which concerns on 1st Embodiment of this invention. It is a half sectional view showing the composition of the mandrel seal part concerning a 1st embodiment of the present invention. It is a disassembled perspective view of the mandrel seal part which concerns on 1st Embodiment of this invention. It is a figure which shows the form of the expansion ring which concerns on 1st Embodiment of this invention, (a) is a top view, (b) is AA sectional drawing of (a), (c) shows a perspective view, ( d) is a schematic side view for explaining the operation of the expansion ring. It is a figure which shows the other Example of the expansion ring which concerns on 1st Embodiment of this invention, (a) is a top view, (b) is BB sectional drawing of (a), (c) is a perspective view. Show. It is principal part sectional drawing which shows the mode at the time of the pipe expansion molding for demonstrating operation | movement of the mandrel seal structure 1 which concerns on 1st Embodiment of this invention. It is sectional drawing for demonstrating the structure of the pipe expansion tool part of the hydraulic pressure pipe forming apparatus which concerns on embodiment of this invention. (A) is a half sectional view showing a conventional mandrel seal structure, (b) is a sectional view showing a configuration of an expansion ring in (a), (c) is a side view thereof, and (d) is a divided type. Sectional drawing which shows the structure of this expansion ring, (e) is the side view. (A) is principal part sectional drawing for demonstrating the effect | action at the time of pipe expansion in the conventional mandrel seal structure, (b) is the elements on larger scale of (a).

Explanation of symbols

1 Mandrel seal structure 2 O-ring (enclosure)
3 Backup ring 4 Movable ring member 5 Spacer 8 Tube (bag-shaped rubber member)
DESCRIPTION OF SYMBOLS 10 Mandrel seal part 11 Fluid pressure expansion forming apparatus 12 Tube expansion tool part 41, 41 'Expansion ring 41a Taper-shaped recessed part 41b, 41b' Slot part 41c Wide diameter recessed part 41d Slot surface 41h 'Snap ring (holding member)
42 Fixing ring 42a Wedge-shaped part P Ultra-high pressure chamber W1 pipe (workpiece)
W2 tube sheet

Claims (6)

A mandrel seal portion for enlarging and forming an ultrahigh pressure liquid between the workpiece, a tube expansion tool portion for injecting the ultrahigh pressure liquid into the mandrel seal portion, and supplying the ultrahigh pressure liquid to the tube expansion tool portion A mandrel seal structure in the mandrel seal part of a hydraulic expansion tube forming apparatus having a main body part,
The mandrel seal part is
A mandrel connected to the tube expansion tool portion and introduced with the ultra-high pressure liquid;
An enclosing unit that is attached to the outer periphery of the mandrel and encloses the ultrahigh pressure liquid between the work and the mandrel to form an ultrahigh pressure chamber;
An annular movable ring member disposed on at least one side of the ultra-high pressure chamber so as to hold the sealing means in the axial direction of the mandrel, and externally fitted to the mandrel;
This movable ring member
A fixing ring having a wedge-shaped portion whose outer diameter is reduced toward the end surface,
A tapered recess having an inner diameter expanded toward the end face so as to be adapted to the wedge-shaped portion, and the wedge-shaped portion is pressed against the tapered recess by the hydraulic pressure of the ultra-high pressure liquid. And an expansion ring provided with an expandable slit part,
In the slit portion, a slit surface is formed along a direction intersecting the axial direction of the expansion ring from one end surface to the other end surface from the outer peripheral surface to the inner peripheral surface of the expansion ring. A mandrel seal structure characterized by that. The slit portion is provided in one place in the circumferential direction of the expansion ring;
The mandrel seal structure according to claim 1. The slits are provided at least in two locations in the circumferential direction of the expansion ring,
The mandrel seal structure according to claim 1, wherein a holding member that urges the expansion ring toward the center of the expansion ring is provided on an outer peripheral portion of the expansion ring. The enclosing means is a seal member fitted on the mandrel;
4. The structure according to claim 1, wherein the sealing member is interposed between the workpiece and the mandrel so that the ultra-high pressure liquid is sealed. 5. The mandrel seal structure according to the item.   The mandrel seal structure according to any one of claims 1 to 3, wherein the enclosing member is a bag-like rubber member. A backup ring made of an elastic member is interposed between the enclosing means and the movable ring member,
In the movable ring member, an expansion ring is disposed on the backup ring side, and a diameter-enlarged recess having a tapered shape whose diameter is expanded toward the end surface side is provided on an end surface of the expansion ring on the backup ring side. The mandrel seal structure according to any one of claims 1 to 5, wherein:

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