JP4515380B2 - Method and apparatus for forming tubular member - Google Patents

Description

  The present invention relates to an improvement of the filling and pressurizing apparatus disclosed in US Pat. No. 5,235,836, issued August 17, 1993. Such filling and pressurizing devices, such as those disclosed in U.S. Pat. No. 4,567,743, issued February 4, 1986, and U.S. Reissue Patent 33,990, issued July 14, 1992. It can be used by expansion formation, which is a non-limiting example. Another use could be a tube pressure test.

According to one aspect, (a) providing a die in which a cavity having a cross-section having an outer shape corresponding to the outer shape of a molded tubular member is formed;
(B) providing a hollow blank with an end having an initial cross section across the long axis of the hollow blank;
(C) deforming the end of the hollow blank to have a deformed cross section different from the initial cross section;
(D) constraining a hollow blank with an end having a deformed cross-section in the cavity;
(E) sealing a hollow blank by applying a seal member having a shape corresponding to the deformed cross section into an end portion having the deformed cross section;
(F) pressurizing the inside of a hollow blank that is sealed and restrained in the cavity, and molding the blank so that the blank becomes the shape of the cavity;
(G) removing the sealing member from the blank to release the pressure, and taking out the blank formed from the die, and
The die has a plurality of die sections that are relatively movable between an open position, an intermediate position, and a closed position, each having a die cavity portion and a corresponding face portion, and The die section is in a closed position, with the corresponding face portions abutting each other to define the cavity by the die cavity portion, and
The step of deforming the end of the hollow blank includes disposing the blank between the die sections at the open position and the intermediate section for deforming the end. And bringing them into close proximity to each other, and
The sealing member was molded (a) by forming a tubular member that is inserted into the deformed end before moving the die section to a closed position and constraining a blank into the cavity. Providing a die formed with a cross-sectional cavity having an outer shape corresponding to the outer shape of the tubular member;
(B) providing a hollow blank with an end having an initial cross section across the long axis of the hollow blank;
(C) deforming the end of the hollow blank to have a deformed cross section different from the initial cross section;
(D) constraining a hollow blank with an end having a deformed cross-section in the cavity;
(E) sealing a hollow blank by applying a seal member having a shape corresponding to the deformed cross section into an end portion having the deformed cross section;
(F) pressurizing the inside of a hollow blank that is sealed and restrained in the cavity, and molding the blank so that the blank becomes the shape of the cavity;
(G) removing the sealing member from the blank to release the pressure, and taking out the blank formed from the die, and
The die has a plurality of die sections that are relatively movable between an open position, an intermediate position, and a closed position, each having a die cavity portion and a corresponding face portion, and The die section is in a closed position, with the corresponding face portions abutting each other to define the cavity by the die cavity portion, and
The step of deforming the end of the hollow blank includes disposing the blank between the die sections at the open position and the intermediate section for deforming the end. And bringing them into close proximity to each other, and
The sealing member provides a method of forming a tubular member that is inserted into the deformed end before moving the die section to a closed position and constraining a blank into the cavity.

  Preferred embodiments of the filling and pressurizing apparatus for carrying out the above aspects of the present invention will be described in detail below by way of example with reference to the accompanying drawings.

  As shown in FIGS. 1 and 2, the die 10 to be inflated is vertically supported with respect to a lower part 11 supported and fixed to a surrounding object such as a store floor, and a lower part 11 with respect to the lower part 11 by a press structure (not shown). And an upper portion 12 movable in the direction. For example, the lower part 11 can be connected to a fixed frame supported on the floor. The lower portion 11 may also include a lower die section 13 having a substantially groove-shaped die cavity portion 14 therein. The upper die section 16 is provided with a die cavity portion, and when the sections 13 and 16 are closed to each other, a die cavity (that is, a cavity) having an end opened therein is formed. Then, the hollow tube, that is, the end of the cylindrical blank (hollow blank) 17 can be expanded and molded. This blank 17 is placed between the die sections before being closed and is filled with liquid (usually water) using a filling pressurization device provided on each end side of the die 10, indicated at 18 on one end side. ) Is filled and pressurized. This pressurization is sufficient to expand the blank 17 to form a die cavity replica.

  A clamp member 19 is attached to each end of the upper die section. 1 and 2 show only the clamp member 19 on one end side, the same configuration is also formed on the other end side. The clamp member 19 is supported by a floating link mechanism having a vertical side wall structure 21 and a stop 22 so that the clamp member 19 can move in the vertical direction with respect to the upper die section 16 and the downward movement is restricted by the stop 22. ing. The compression spring 23 always urges the clamp member 19 downward to the restriction position shown in FIG. At this position, the lower end 24 of the clamp member 19 extends downward from the upper die section 16.

  In the intermediate position where the upper die section 16 is closed, the opposing surfaces of the sections 13, 16 are slightly spaced from each other, typically 10-25% of the diameter of the blank 17, and the lower end 24 of the clamping member 19 is the lower die section. 13 and is urged upward against the urging force of the compression spring 23. Due to this elastic action, the end portion of the blank 17 is firmly held between the adjacent end portion of the die cavity portion 14 and the arcuate cavity portion 26 formed below the clamp member 19.

  When the blank 17 is formed in a rectangular cross section, it is preferable that the end portion of the blank 17 is first formed into an elongated and smoothly rounded shape such as a smoothly rounded hourglass shape or an elliptical shape. In such a case, the end portions of the die cavity portion 14 and the cavity portion 26 are effective for deforming the end portion of the blank 17 into an elongated shape. Otherwise, the clamp member 19 and the die cavity portion 14 will grip the end portion of the blank 17 without substantially deforming. In the example shown, the end of the blank 17 is first deformed into an elliptical cross section.

  As shown, a box-shaped high speed / low pressure fluid conduit 27 is provided. A similar mechanism is provided at each end of the device (die) 10. This conduit 27 is formed by a partial fluid conduit comprising a first or lower conduit section 27 a fixed to the lower die section 13 and a second or upper conduit section 27 b connected to the clamping member 19. . These sections constitute a box closed together in the intermediate closed position shown in FIG.

  These sections 27a, 27b may be configured in the same way to facilitate mounting of the sections 27a, 27b to the lower die section 13 and the clamp member 19 using, for example, threaded studs (not shown). Thus, the front walls 28a and 28b are preferably provided.

  These front walls are formed with partial cavities 29a and 29b that fit into the die cavity portion 14 of the lower portion 11 and the cavity portion 26 of the clamp member 19, respectively. Usually, the cylindrical blank 17 has slight differences and errors, and in order to reduce the overall length of the device 10, the dimensions of the front walls 28a, 28b are such that the end of the blank is at the front wall according to the blank length error. It is set to be located at one point along the thickness of 28a, 28b. When both end portions of the blank 17 are deformed into an elongated shape at an intermediate position between the lower portion 11 and the upper portion 12, the front walls 28a and 28b act on the blank 17 to deform into such a shape. Preferably, the partial cavities 29a, 29b are set to a size sufficient to receive half of the outer periphery of the blank 17. For example, each partial cavity 29a, 29b can be formed in a semi-elliptical shape. Further, the front ends of the front walls 28a and 28b substantially coincide with the matching surfaces of the lower die section 13 and the clamp member 19, and the arrangement of the blank 17 between the lower portion 11 and the upper portion 12 and the last of the molding recycling are performed. It is easy to take out from between the lower part 11 and the upper part 12 at the opening position of the molded blank. The front wall 28a of the lower conduit section 27a is relatively shallow, while the rear wall 31a is deep to receive a portion 18a of the seal head forming portion of the device 18 described below. This part 18a is fixed to the cavity defined between the die cavity part 14 and the cavity part 26 at the intermediate position described above and to the peripheral part as well as to the lower part 11, thus to the lower conduit section 27a. The cylinder block 32 can be moved back and forth in the axial direction. Further, this part 18a passes through the opening 33 formed in the wall 31a. The opening 33 is provided with an O-ring seal in order to prevent liquid from leaking around the part 18a. Both side walls 34a are inclined upward toward the upper conduit section 27b from the front to the rear. Similarly, the side wall of the section 27b is tapered from the front side to the rear side when viewed from the side, and as a result, the lower conduit section 27a and the upper conduit section 27b abut against each other at a rearwardly inclined surface. ing. Grooves are formed in the upper surfaces of the front walls 28a and 31a and the side walls 34a to accommodate the substantially C-shaped elastic seal gasket 36. This gasket 36 engages the lower surface of the wall of the upper conduit section 27b to prevent water from leaking when the sections 27a, 27b are closed.

  An inlet opening 37 is formed in the side wall 34a of the lower conduit section 27a, and a relatively large diameter conduit 38 is connected to the opening. This conduit is preferably formed by a substantially rigid tube, for example a metal pipe. The conduit 38 shown schematically in FIG. 2 is connected to a liquid source 41 via a valve 39. This liquid source can supply a relatively high flow rate, ie, a high flow rate and a relatively low pressure fluid.

  In use, the lower conduit section 27a and the upper conduit section 27b are located between the lower die section 13 and the clamp member 19 when the lower portion 11 and the upper portion 12 are closed in the intermediate position as shown in FIG. The box-shaped conduit around the mouth of the tube (blank 17) gripped in step (i.e., the obturator 27), whether it is deformed like an ellipse or initially rounded or annular, Also configure. After this, the valve 39 is actuated and the tube 17 is filled with liquid from the fluid source 41 through the closure 27 from one end of the tube 17 under a low pressure, for example, slightly higher than atmospheric pressure. Filled with flow rate. At the same time, it is connected to a conduit similar to the closing body 27, that is, the closing body, and a valve similar to the valve 39 is operated to discharge liquid from the other end of the tube to the atmosphere. This discharge is stopped when the liquid filling operation is completed.

  The filled tube 17 is sealed and pressurized using a seal and pressurizer described later or a known form of seal and pressurizer.

  It is possible to make changes to the apparatus described above. For example, although an occluder having two sections, i.e., a conduit 27, has been described, the movable upper conduit section 27b is a closure that defines a conduit, i.e., occluder, similar to the occluder 27, independently or integrally with one another. The position may be constituted by a plurality of subsections moved from the open position.

  The sealing and pressurizing device as described above has a block 32 which is supported on a peripheral portion, for example, on the floor of a store and fixed to a frame which supports the lower portion 11. The block 32 has a bore including a rear portion 42, a slightly small-diameter intermediate portion 43, and a large-diameter front portion 44. The rear portion 42 accommodates a cylindrical lining 46 whose rear end is sealed with an O-ring seal, a cylindrical head end 48, an O-ring 49, a ground retainer 51, and a ground 52. A cylindrical space is defined. A seal retainer 53 and an O-ring seal 54 are provided at the other end of the lining 46, and a thrust gland attached to the blank 32 by an O-ring 56, a gland 57, and a threaded stud 59. It is sealed with a retainer 58.

  A rod 61 having a bore 62 therethrough passes through the block 32. The rod is formed with a large-diameter piston portion 63 slidable with respect to the lining 46. Pressure fluid is supplied to the cylindrical space through the bore 43 and the inlet formed near the cylindrical head end 48, respectively, and the rod 61 moves in the retracted position and the advanced position shown in FIGS. 2 and 4, respectively. Can be reciprocated between.

  The upper and lower mounting parts 64, 66 engage in slots formed outside the rear end of the rod 61 and are arranged on both sides of the rod outside the cross section, thus not shown in FIG. It is clamped in a tight engagement in the rod 61 by a fastening member such as a stud. The side surfaces of these portions 64 and 66 are in sliding engagement with a surface 67 formed in the block 32 so as to extend in the longitudinal direction. As a result, the rod 61 is prevented from rotating about its axis. ing. An inlet mounting member 68 is attached to the mounting portions 64, 66 by a threaded stud 69. The mounting member 68 has a tapered opening 71, which is connected to the flexible conduit 72 by a screw connection (not shown). This conduit 72 is connected via a valve 73 to a fluid pressure adduct, i.e. a liquid source 74, which supplies liquid at a low flow rate, i.e. at a low flow rate and under high pressure.

  At the other end of the rod 61, that is, at the front end, an annular end portion 76 having a relatively thin step portion is formed. This end holds a seal head denoted by reference numeral 77. In the illustrated example, the head 77 has an elliptical cross section to engage correspondingly with the deformed end of the tube 17 but the end of the tube is rounded, i.e., cylindrical. In this case, the head 77 is of course a circular cross section. In this example, the head 77 has a circular bore into which the rod end 76 is inserted, and thus has a sleeve 78 slidable axially at this end. The outer peripheral surface of this sleeve has an elliptical cross section. An O-ring 79 is provided in the sleeve 78 so that high pressure liquid does not leak out of the rod 61. An annular recess 81 is formed on the inner surface near the tip of the sleeve 78, and the rear surface of the recess defines a stop surface 81a.

  In the illustrated preferred form, an elastic ring member 82 having an elliptical outer peripheral surface and a circular cross-sectional bore is provided on the outer periphery of the collar member 83. This collar member extends slightly inward beyond the inner end of the ring member 82 and is usually a thin annular collar member 84 spaced from the stop surface 81a as shown in FIG. 5, a circular inner bore and an oval shape. And an inner shoulder 86 having an outer surface. The collar member 83 is slidable in the axial direction on the rod 61. Preferably, the front end is smoothly curved outward as indicated by reference numeral 87, so that the gas This makes it easy to insert into the rear end. A C-shaped retaining clip 88 is fitted in a slot formed in a corresponding shape near the end of the rod end 76 so that the shoulder 86 lightens the elastic ring member 82 lightly. Maintained in a compressed state. In such a state, the outer side of the ring member 82 is preferably pushed inward between the shoulder portion 86 and the end face of the sleeve 78 as shown in FIG.

  In use, the seal head 77 is inserted into the open end of the tube 17 to be sealed as the rod 61 advances as shown in FIGS. Further, the sleeve 78 is provided with blocking means such as an annular portion (a part) 18a so as to restrict the rod 61 from retracting while the rod 61 is retracting. Such blocking means are disclosed, for example, in the aforementioned US application No. No. 07 / 860,553 may be used, and the configuration described later with reference to FIG. 3 may be used. As the shoulder 86 clamped by the retaining clip 88 is pulled against the sleeve 78, the resilient ring member 82 is compressively deformed and protrudes radially outward to contact the inner surface of the blank 17. As shown in FIG. 6, the collar member 84 abuts against the stop surface 81 a to restrict the deformation force applied to the ring member 82, and avoids the disadvantage of damage to the ring member 82 and excessive force applied to the wall of the tube 17. ing.

  Various modifications are possible. For example, although not relatively effective, instead of providing the collar member 84 that engages with the stop surface 81a, another form of stop member provided on or connected to the rod 61 is provided on the sleeve 78 or connected to the stop surface. Can be used to engage. Instead, the outer shape of the compression restriction device is the same as that of the above-mentioned US patent application no. 07 / 860,553 can be used. Further, instead of the seal on the inner wall of the sleeve 17, the above-described head 77 and sliding force regulating collar member 83 are the same as those described in US Pat. 5,235,836 can be modified by those skilled in the art to form a seal on the outside of the tube 17 wall.

  In this case, the outer sleeve portion can be engaged with a collar similar to the collar member 83 and can be displaced. Further, it is possible to provide a stop surface where the inner rod portion engages with the collar at a place where compression of the elastic seal is restricted.

  In a preferred form, part 18a comprises a cylinder 89 as shown in FIG. 3 having a bore. The bore includes a relatively wide rear portion 91 that accommodates the main portion of the rod 61 and a narrow front portion 92 that accommodates a small-diameter front end portion 76. The cylinder 89 is normally kept engaged with the front end of the main portion of the rod 61 by the compression force applied by the holding clip 88 as shown in FIG. The rear portion 91 of the bore is formed with a slot for slidably storing a key 94 attached to the rod 61, that is, a key groove 93. As a result, the cylinder 89 is in the surroundings of the rod 61 and thus the surrounding portion. Rotation against is prevented. Therefore, the cylinder 89 has a head 77 centered on the axis of the rod 61 that is out of alignment with the opening restricted between the lower die section 13 and the clamp member 19, that is, between the front wall 28a and the front wall 28b. The rotation of the constituent members is prevented.

  The cylinder 89 is inserted into the outer cylinder 96 in a retractable manner. The outer cylinder 96 is accommodated in a large-diameter front portion 44 of the bore in the block 32. The outer cylinder 96 has a small-diameter inner rear end portion 97 that is rotatably supported with respect to the ground member 57. The outer side of the front end of the outer cylinder 96 is rotatably supported in a guide bush 98 connected to the front side of the block 32.

  Inside the outer cylinder 96, a series of three abutting members 99 are formed in this embodiment, which are spaced apart from each other at equal intervals around the axis of the outer cylinder 96 and extend inward. Further, the same number of channels 101 as the contact members 99 are formed outside the rear portion of the cylinder 89 and spaced apart from each other at equal intervals in the circumferential direction and extending in the axial direction. The contact member 99 is inserted so that the cylinder 89 can move in and out of the outer cylinder 96. The rear end of each channel 101 ends at a circumferentially extending recess 102 that provides a radially extending stop surface 103.

  A ring gear 104 is attached to the inner end of the outer surface of the outer cylinder 96 in order to rotate the outer cylinder 96 about this axis. The gear 104 is driven by a rack 106 that can run in a slot 107 that extends in the lateral direction in the block 32. A reciprocating drive 108, such as an index cylinder / piston mechanism, is connected to the rack 106 so that the rack 106 can be reciprocated to reciprocate the gear 104 and thus the outer cylinder 96. .

  In the typical cycle operation of this device, the filling and pressurizing device is first installed in the position shown in FIGS. 1 and 2, and a cylindrical, usually cylindrical blank 17 is shown in FIG. It arrange | positions between the lower part 11 and the upper part 12 of such an open state. Next, as the upper conduit section 27b is lowered onto the lower conduit section 27a and sealed to form a box-shaped conduit 27 as shown in FIG. 2, the lower portion 11 and the upper portion 12 are closed to an intermediate position and the tube The end of 17 is deformed to have an elliptical cross section, and, as between the front wall 28a and the front wall 28b, the outside of the die cavity portion 14, that is, between the throat portion and the clamp member 19. Then hold it. Thereafter, the tube 17 is filled with the liquid through the conduit 38 by the high flow rate and low pressure filling operation as described above. Prior to this filling, the valve 73 connected to the bore 62 of the rod 61 is closed.

  Further, pressure is supplied to the cylinder containing the piston 63 to move the rod 61 forward as shown in FIG. 4, and the head 77 is inserted into the end of the tube 17 as shown in FIGS. Let As the head 77 moves forward, the rod 61 extends the cylinder 89 out of the outer cylinder 96 as shown in FIG. Then, the drive mechanism 108 is driven to rotate the outer cylinder 96 to engage the contact member 99 in the recess 102. Next, the drive of the piston part 63 is reversed, and the rod 61 is retracted backward as shown in FIG. The reverse movement of the sleeve 78 and the cylinder 89 is restricted by the contact member 99 engaging the stop surface 103, and as a result, compression and sealing of the elastic ring member 82 occurs in the tube 17 as described above. As described above, the same gripping, deformation, sealing and pressurizing mechanisms are used at each end of the tube 17, and the sealing by the head 77 is used to connect the inside of the tube 17 to the inside of the box-shaped conduit 27. Isolate from high speed / low pressure circuit (fluid source) 41.

  The valve 73 as well as the low-speed / high-pressure fluid source 74 are operated and US Pat. In order to avoid pinching the tube 17 between the upper die section 16 and the lower die section 13 during a filling block as described in 33990, a preload is applied in the tube 17. The lower die section 13 and the upper die section 16 are sufficiently closed to regulate the pressure in the tube 17 during die closing by a pressure relief valve connected to the line 72 or provided in the valve 73. While this is fully closed, the clamp member 19 is displaced slightly upward from the upper die section 16 against the biasing force of the compression spring 23. This pressure relief valve is then deactivated and the high pressure liquid source 74 is activated, sufficient to expand the tube 17 to the shape of the die cavity formed between the lower die section 13 and the upper die section 16. Supply appropriate pressure into the tube.

  The pressure in the tube 17 is released, the device 108 is operated to unlock the return operation of the cylinder 89 and the piston portion 63, and these are moved rearward to the position shown in FIG. Then, the lower part 11 and the upper part 12 are opened, and the molded blank 17 is taken out. Then, such an operation cycle is repeated.

FIG. 7 is a partial perspective view for explaining a die for forming a tube expansion together with a filling and pressurizing device in an open position. 2 is a partial longitudinal cross-sectional view of the die and device of FIG. 1 showing the filling device in the closed position and the pressure device in the retracted state. FIG. FIG. 3 is a partially exploded perspective view of a block device used in the apparatus shown in FIGS. 1 and 2. FIG. 3 is a view corresponding to FIG. 2 in which the pressure device is in an extended state. It is an expanded sectional view of the seal head of the pressurizing device in a non-sealed and sealed state. It is an expanded sectional view of the seal head of the pressurizing device in a non-sealed and sealed state.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Die, 13 ... Lower die section, 14 ... Die cavity part, 16 ... Upper die section, 17 ... Hollow tube (hollow blank), 19 ... Clamp member, 27a ... Lower conduit section, 27 ... Closure body, 27b ... upper conduit section, 36 ... elastic seal gasket, 46 ... lining, 49, 79 ... O-ring, 51 ... gland retainer, 52 ... gland, 61 ... rod, 74 ... liquid source, 77 ... seal head.

Claims (16)

(A) providing a die in which a cross-sectional cavity having an outer shape corresponding to the outer shape of the molded tubular member is formed;
(B) providing a hollow blank with an end having an initial cross section across the long axis of the hollow blank;
(C) deforming the end of the hollow blank;
(D) constraining a hollow blank with the deformed end in the cavity;
(E) applying a sealing member having a shape corresponding to a cross section of the deformed end portion into the deformed end portion to seal a hollow blank;
(F) pressurizing the inside of a hollow blank that is sealed and restrained in the cavity, and molding the blank so that the blank becomes the shape of the cavity;
(G) removing the sealing member from the blank to release the pressure, and taking out the blank formed from the die, and
The die has a plurality of die sections that are relatively movable between an open position, an intermediate position, and a closed position, each having a die cavity portion and a corresponding face portion, and The die section is in a closed position, with the corresponding face portions abutting each other to define the cavity by the die cavity portion, and
The step of deforming the end of the hollow blank includes disposing the blank between the die sections at the open position and the intermediate section for deforming the end. And bringing them into close proximity to each other, and
The sealing member is inserted into the deformed end before moving the die section to the closed position to constrain the blank in the cavity. In the step of sealing the hollow blank, the sealing member includes first and second compression members spaced apart from each other in the longitudinal direction, an elastic seal portion disposed between the compression members, and the compression member. 2. The method of claim 1, comprising means for compressing the elastic seal so that the elastic seal is expanded in a lateral direction and elastically engages the blank wall. The method of claim 2, wherein the seal member expands radially outward to abut the inner surface of the blank. 4. The method according to claim 1, wherein the seal member is inserted into the deformed end , and the seal member has an outer diameter corresponding to a cross section of the deformed end . In the step of providing the die, at least one of the die sections has a clamp member connected to the die section via a link mechanism, and the clamp member has a cross section that is smoothly deformed into a curve. A cavity having a shape is defined together with the other die section, and the clamping member is biased in the direction of the other die section so that the one die section is moved from the open position to the intermediate position. The end of the blank is deformed in cooperation with the one die section and remains stationary relative to the other die section when the one die section is moved from the intermediate position to the closed position. 5. The method according to any one of claims 1 to 4. 6. The method of claim 5, wherein the clamping member grips the end of the blank before the one die section contacts the blank. Before the one die section is moved from the intermediate position to the closed position, the blank exceeds the elastic limit of the blank wall and the blank between the corresponding faces in the closed position of the die section. The method according to claim 5 or 6, wherein the pressure is applied at a first pressure so as to avoid pinching. 8. A method according to any one of the preceding claims, wherein the initial cross section or the cross section of the deformed end is elliptical. The method of claim 8 , wherein the cross- section of the deformed end is elliptical. (A) a plurality of die sections, wherein the die sections are passed from an open position where a cylindrical blank having an initial cross-section is disposed between the die sections, through intermediate positions close to each other; A die section movable between the die sections to a closed position defining a cavity in which the cylindrical blank is deformed, the cavity being open at at least one end of the die section;
(B) a clamp member attached to at least one end of one of the die sections by a link mechanism and biased by a biasing means to a normal position protruding in the closing direction with respect to the one die section; The clamping member is adapted to cause the end of the other die section to engage and grip the blank so that the blank is positioned relative to the other die section before the one die section contacts the blank. And, together with the other die section, defining a cavity portion near the opening of the cavity, the cavity portion having a curved profile different from the profile of the initial cross-section, and the clamping member , When the die section is moved from the intermediate position to the closed position, the closed position is moved against the action of the biasing means. While being biased in a direction opposite to the direction, deforming the end portion of the tubular blank so as to have the curved contour, and the clamping member,
(C) a seal member having an outer shape corresponding to the outer shape of the cavity portion and capable of reciprocating so as to be inserted into and removed from the deformed end portion;
(D) An apparatus for forming a tubular member, comprising: a pressure fluid supplying means for pressurizing the blank through the seal member so as to match the shape of the cavity. The sealing member urges the first and second compression members spaced apart from each other in the longitudinal direction, an elastic seal portion disposed between the compression members, and the compression member so as to approach each other, and the elastic seal 11. The apparatus of claim 10, comprising means for inflating the section laterally to resiliently engage the deformed end of the blank. The apparatus of claim 11, wherein the seal member is provided inside a blank and the elastic seal portion expands radially outward. Means for forming a box of low-pressure fluid in the intermediate position and sealed to the clamping member defining the cavity and the die section, the box being reciprocable; A rear opening that is slidably and sealably engaged with the seal member and a low-pressure fluid connection, and when in the intermediate position, before the seal member engages the deformed end; 13. Apparatus according to any one of claims 10 to 12, wherein low pressure fluid is supplied to the blank so as to fill the blank with low pressure fluid through the fluid connection. 14. The cavity according to any one of claims 10 to 13, wherein the cavity is open at each end of the die section, and the clamp member and the seal member are disposed at each end of the die section. apparatus. 15. A device according to any one of claims 10 to 14, wherein the curved profile is elongated. 16. The apparatus according to any one of claims 10 to 15, wherein the outer shape is an ellipse.

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