US3685327A

US3685327A - Bulging apparatus

Info

Publication number: US3685327A
Application number: US875967A
Authority: US
Inventors: Masanobu Nakamura
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-11-12
Filing date: 1969-11-12
Publication date: 1972-08-22
Anticipated expiration: 1989-08-22

Abstract

A fluid pressure bulging apparatus for bulging tubular work is connected with a pressure generating means. A dummy block is fitted to one end of the tube being worked in order to automatically move the work axially by the hydraulic fluid pressure which is exerted on the inside of the work.

Description

United States Patent Nakamura 1451 Aug. 22, 1972 1 BULGING APPARATUS [72] Inventor: Masanobu Nakamura, 2-10-2,

Shichirigahama, I-ligashi, Kamakura,Japan 22 Filed: Nov. 12, 1969 [21 Appl. No.: 875,967

3,494,160 2/ i 970 Tominaga et al. ..72/60 3,105,537- 10/1963 Foster ..72/370 FOREIGN PATENTS OR APPLICATIONS 24,746 10/ 1969 Japan ..76/56 Primary Examiner-Richard J. Herbst Attorney-Jacobi, Lilling & Siege] [57] ABSTRACT A fluid pressure bulging apparatus for bulging tubular work is connected with a pressure generating means. A dummy block is fitted to one end of the tube being worked in order to automatically move the work axially by the hydraulic fluid pressure which is exerted on the inside of the work.

1 Claim, 2 Drawing figures PATENTED M1822 m2 5 on B 6 mm 3 mm 3 mm E mm mm 0w 5 mm INYENTOR Maia/a8 ///7Ki/W 4 R A j/aww' Aim 50% ATTORNEYS BULGING APPARATUS This invention relates to a bulging apparatus for bulging part of pipe to a desired contour with pressure exerted by hydraulic means on fluid filled in the blank.

It is a principal object of the present invention to provide a bulging apparatus wherein only one ends of dies are connected to a piston chamber of hydraulic pres sure generating means and the piston in said chamber is actuated to apply a pressure to the hydraulic fluid filled in a length of pipe placed in the cavity of the dies so that the bulging can be accomplished without the need of any external piping.

Another object of the invention is to provide a bulging apparatus wherein a dummy block fitted to one end of pipe being worked is automatically moved axially by hydraulic fluid as pressure is exerted on the fluid inside the pipe in the manner above described, so as to support the pipe end firmly and securely and permit the bulging to be performed in a reliable way.

Another object is to provide a bulging apparatus wherein air inside the pipe to be worked is automatically bled off as the pipe is filled with hydraulic fluid.

Still another object is to provide a bulging apparatus wherein a support pad fitted to the front end of the pipe is moved axially and pulled off from the pipe with ease on completion of a bulging operation, so that the bulged pipe can be readily removed from the die cavity.

These and other objects of the present invention should become apparent from the following detailed description taken in conjunction with the accompanying drawings showing embodiments thereof.

In the drawings:

FIG. 1 is a longitudinal sectional view of an embodiment of the invention; and

FIG. 2 is a similar longitudinal sectional view of another embodiment of the invention.

In FIG. 1 there is shown a longitudinal section a bulging apparatus embodying the invention wherein application of a pressure to the hydraulic fluid causes a pipe to be worked inside to be pressed at the rear end in the axial direction.

In the figure, reference numeral 1 generally indicates dies of split type comprised of an upper die 2 and a lower die 3, each formed with a recess axially on the surface opposite to each other, thus defining a cavity 4 to receive a length of pipe 5 as a work to be bulged.

The cavity 4 is communicated at the rear end, or at the left end as viewed in the figure, with a piston chamber 6 of a hydraulic pressure generator 7 via a tapered passage 8, in such a manner that, when the cavity 4, passage 8, and piston chamber 6 are filled with hydraulic fluid and a piston 9 provided through the top wall of the piston chamber is suitably moved downward to exert a pressure on the fluid inside the chamber, the pressure is transmitted through the passage 8 into the cavity 4.

Inside the cavity 4 there is suitably held a bleed pipe 10 for discharging air out of the blank 5 as the latter is filled with the hydraulic fluid. The bleed pipe 10 is bent slightly upward at the front end 1 1, and is open near the inner wall surface of the pipe portion to be bulged. The bleed pipe 10 is provided with a valve 12 at a suitable point.

At the entrace of the cavity 4 is provided a pressure member or dummy block 13 which in response to the pressure of the hydraulic fluid automatically presses the base end or the left end of the pipe 5 forward to secure a grip of the pipe for working.

The dummy block 13 is a cylinder having a through hole in the center and is slidably inserted in the left-end entrance of the cavity 4, while maintaining liquidtightness as with an O-ring 14. At its lower end portion the block 13 is stepped to form a reduced-diameter portion 15, which just fits in the mating end of the pipe 5. Thus, the area of the left end face 16 of the dummy block which is subjected to the hydraulic pressure is somewhat larger than the pressure-receiving area of the right end face 17.

Accordingly, if the piston 9 of the hydraulic pressure generator 7 is actuated downward to exert a pressure on the hydraulic fluid in the fluid passage 8 and also in the pipe 5 inside the cavity 4 of the dies 1, the left end fact 16 of the dummy block 13 is subjected to a greater fluid pressure than is the right end face 17 with the result that the pressure differential causes the reduced diameter portion 15 of the dummy block 13 to be fitted securely into the left end portion of the pipe 5 and thereby press the left end of the pipe 5.

The base or rear end portion of the upper die 2 of the dies 1 is pivotally connected to the hydraulic pressure generator 7 with horizontal pivot or pin 18 in such a way that the upper die can turn up around the pivot to open or close the dies.

The frontal exterior of the dies 1 is tapered over a desired length, so that a clamping cylinder or sheath 19 having a matching tapered inner wall can be moved toward the hydraulic pressure generator 7 by suitable means thereby to clamp the upper die 2 and the lower die 3 firmly together.

Inside a hole 20 formed in the frontal ends of the dies 1 there is inserted, slidably with an O-ring 21, a support pad 22 which is fitted in the right end portion of the pipe 5 to provide a support to the pipe. A threaded portion 23 at the outer end of the support pad 22 is screwed in a nut 24 which fits in an internally threaded hole 25 formed outwardly of the hole 20, so that the support pad 22 can be moved axially as desired by tuming the nut 24.

In the embodiment shown, numeral 26 indicates an outer sleeve for supporting the dummy block 13; 27 indicates an O-ring; 28 indicates a hydraulic fluid line to the piston chamber 6; and 29 indicates a valve provided at a suitable point of the line. 30 is a small passageway which communicates the cavity of the dies with the surrounding atmosphere during the bulging process of the pipe.

The operation of the apparatus according to the present invention will now be explained. First, the nut 24 is turned and the support pad 22 is urged a desired distance into the front end portion of the cavity 4. A length of pipe 5 to be bulged is placed in the cavity 4, with the right end portion being fitted in and supported by an annular space 31 defined between the cavity 4 and the support pad 22, and then both of the

valves

12 and 29 are opened so that hydraulic fluid may be introduced into the pipe 5 by way of the piston chamber the bleed pipe 10, the both

valves

12, 29 are closed and the fluid is no longer introduced into the apparatus.

Next, the piston 9 of the hydraulic pressure generator 7 is forced downward suitably as by a press to exert a pressure on the fluid inside the piston chamber 6, and the pressure is conducted to the fluid inside the pipe thereby to cause bulging of the pipe 5, as desired, to the configuration of the cavity 4 defined by the dies 1.

In the apparatus of the invention, as already stated, the application of a pressure to the hydraulic fluid inside the pipe 5 produces a pressure differential based on the difference between the pressure-receiving areas of the inner and outer end faces 16, 17 of the dummy block 13 fitted in the entrance of the cavity 4 of the dies, which in turn naturally urges the dummy block 13 deep into the cavity 4, until the left end of the pipe is fitted in a space 32 defined between the right end of the dummy block 13 and the cavity 4 and, at the same time, the stepped portion representing a shoulder for the reduced-diameter portion 15 of the dummy block 13 pressed the left end portion of the pipe 5 unmovably.

Thus, with the construction according to the invention, the both ends of the pipe 5 to be bulged are gripped at both the exterior and interior surfaces over desired distances by combinations of the support pad 22 and the cavity 5 and also of the reduced-diameter portion 15 of the dummy block 13 and the cavity 4, and are supported with a pressure axially exerted on the both ends of the pipe 5. This enables the pipe 5 during subsequent working to be accurately bulged without any deviation from the axis. The arrangement also precludes the possibility of undesirable information of the pipe ends due to subjection to any excessive force.

Further, in the apparatus of the invention, the withdrawal of the bulged pipe from the cavity 4 can be accomplished with extreme ease to an advantage because, even if the pipe 5 being worked may be too tightly fastened by the dummy block 13 or the support pad 22, the pipe can be readily liberated by turning the nut 24 and pulling off the support pad 22 from the pipe 5.

FIG. 2 shows, in a longitudinal section, another embodiment of the bulging apparatus of the invention, wherein hydraulic fluid exerts pressure axially on the pipe not only to the rear end but also to the front end thereof.

As shown, dies generally indicated at 41 are of split type, consisting of upper and lower dies, having recesses on the opposing faces to define a longitudinal cavity 42 large enough to receive a length of pipe 43 to be bulged. The rear end portion (or the left end portion as viewed in the figure) of the cavity 42is communicated to a hydraulic pressure generator 44 via a communicating hole or passage 45, while the front end (or the right end) portion faces a chamber 46 contiguous thereto but which is expanded and has a larger diameter than that of the die cavity.

The expanded chamber 46 is defined by inserting a cylindrical body 47 having an end wall 48 at the front end thereof, into the large-diameter hole 49 formed at the front end of the dies 41, so that the space inside the cylindrical body 47 can serve as the expanded chamber 46.

Through a center hole of the front end wall 48 of the cylindrical body 47 there is inserted a stopper 50 slidably and in liquid-tight manner. The stopper is formed suitably with a neck-line small-diameter portion 51 and a medium-diameter portion 52 in one piece, the portion 52 being smaller in diameter than the inside diameter of the pipe 43 to be worked. A hole 53 is formed through the stopper 50, from the inner end face of the medium-diameter portion 52 to the outer end face of the stopper 50.

The intermediate portion 51 of the stopper 50 is fitted in a hole 54 of a cylindrical chuck 55, an O-ring 56 establishing a liquid-tight seal therebetween. The outer surface of the chuck is adapted to slide along the inner wall surface of the expandedchamber 46 while maintaining liquid-tightness by means of an O- ring 57.

The through hole 53 of the stopper s0 is opened in an enclosed chamber 58 defined between the outer end face of the chuck 55 and the inner end face of the front end wall 48 of the cylindrical body 47.

In continuation of the inner end of the hole 54 of the chuck 55, there is formed integrally a tapered hole59 which is slightly increased in diameter at the inner end so that the outeredge of the front end portion of the pipe 43 to be worked can tightly fit therein.

At the rear end of the dies 41, a cylindrical presser or dummy block 60 is inserted in the cavity 42 so as to exert a pressure on the rear edge of the pipe 43 placed inside the cavity 42.

The dummy block 60 is formed at the front end with a stepped, small-diameter portion adapted to fit in the rear end portion of the pipe 43, the small-diameter portion being such that when it is fitted in-the pipe 43 the area at the front'end of the dummy'block 60 which is subjected to the pressure of the hydraulic fluid is smaller than that of the rear end, so that upon application of a pressure to the hydraulic fluid the block 60 is urged frontwardly the pressure differential due to the different pressure is exerted on the rear end portion of the pipe 43.

The rear end portion of the upper die of the dies 41 is pivotally connected with a pivot 61 to the front end portion of a connecting cylinder 62 adjacent the hydraulic pressure generator 44. Thus upper die is movable upward around the pivot 61 to open the dies by suitable hydraulic means not shown.

The exterior of the dies 41 over a desired length from the front end (right end) is tapered, the front end being the smallest in diameter. From the front end of this tapered exterior rearward, a clamping cylinder or sheath 63 having a matching tapered hole 64 is fitted, thus fastening the upper and lower dies tightly together.

After the blank pipe 43 has been bulged, the stopper 50 is caused to slide outwardly by suitable external force. Then, the inner end portion 52 of the stopper 50, which fits in to a shoulder portion 65 of the chuck 55, forces the chuck away from the pipe 43.

The rear end portion of a small-diameter air vent pipe 66 provided through the dummy block 60 extends rearwardly through the communicating passage 45 and the hydraulic pressure generator 44 to an external valve 67 for communication with On the other hand, the front end portion 68 of the vent pipe 66 is bent upwardly substantially in the middle portion of the cavity 42 so that it is open close to the inner wall surface of the pipe 43 to be worked.

In the embodiment shown, reference numeral 69 designates a reservoir for hydraulic fluid in the hydraulic pressure generator 44. A piston 70 exerts a pressure on the hydraulic fluid in the reservoir 69 and hence to the fluid in the pipe 43 held inside the cavity 42 of the dies 41 via the passage 45. The cavity 42 is formed with a spherical recess 71 at a suitable point for bulging purpose. Numeral 72 indicates a line for supplying hydraulic fluid to the reservoir 69, and numeral 73 indicates a valve provided midway the line 72. 74 is a small passageway communicating the recess 71 of cavity 42 with the surrounding atmosphere.

The apparatus of the foregoing construction according to the present invention is operated as follows. A length of pipe 43 to be bulged is placed in the cavity 42 of the dies 41, and the front end (right end) portion of the pipe 43 is fitted in the tapered hole 59 of the chuck 55 inside the expanded chamber 46 and, at the same time, the rear end (left end) portion of the pipe 43 is received with the dummy block 60, and the

valves

67 and 73 are opened so that hydraulic fluid may be introduced into the reservoir 69, passage 45, and pipe 43.

Then, asthe fluid enters the pipe 43, the air inside the pipe 43 is driven out through the air vent pipe 66. When the bleeding has been completed, or when the fluid has begun overflowing from the outer end of the vent pipe 66, the

valves

67 and 73 are both closed.

Next, the piston 70 of the hydraulic pressure generator 44 is forced downward suitably as by a press to exert a pressure on the fluid in the reservoir 69 and the fluid pressure in turn is transmitted to the fluid inside the pipe 43, so that the pipe 43 is bulged as desired to the contour of the cavity 42.

The front end portion of the pipe 43, which is fitted in the tapered hole 59 of the chuck 55, is urged into closer engagement with the latter upon the application of the pressure to the hydraulic fluid in the pipe 43, whereby the front end portion of the pipe 43 is rigidly and securely gripped and held under pressure.

As hydraulic fluid is forced into the pipe 43, part of the fluid flows through the hole 53 of the stopper 50 into the enclosed chamber 58 between the outer end face of the chuck S5 and the front end wall 48, thereby to urge the chuck 61 backward.

Since the stopper 50 is slidable with respect to the front end wall 48 of the cylindrical body 47, the chuck 55 is urged out, together with the stopper 50, toward the pipe 43, with the result that the tapered hole 59 gets in closer engagement with the front end portion of the pipe 43.

Accordingly, the front end portion of the pipe 43 is tightly gripped by the tapered hole 59 of the chuck 55 and is held under pressure by the engagement with the shoulder 65 of the chuck 55. This makes it possible to perform bulging of the pipe 43 accurately without any possibility of positional deviation or vibration.

After the bulging of the pipe 43, the chuck 55 is suitably slid out to leave the front end portion of the pipe 43 away therefrom, and the sheath 63 is slid off outwardly from the dies 41. Then, the upper die of the dies 41 is turned upwardly around the pivot 61 to open the dies and remove the bulged pipe 43 readily and simply from the cavity 42 to a great advantage.

What is claimed is. l. A bulging apparatus of the type employed to shape a pipe by means of hydraulic fluid under pressure, said apparatus comprising: cavity means having a cavity therein for receiving the pipe and having an enlarged front end and a rear end, said rear end of said cavity closely conformed to the external cylindrical dimensions of the pipe; retaining means, for retaining the pipe at said front end of said cavity, comprising a chuck within said enlarged said front end portion and in sealing engagement with the walls of said cavity such that a portion of said enlarged portion is in front of said chuck and separated thereby from the remainder of said cavity, said chuck is adapted to grasp the pipe such that as the fluid pressure is increased the pipe is forced into greater engagement with said chuck, said chuck having an aperture extending axially therethrough, a stopper extends within said chuck through said chuck aperture, said stopper having an aperture therein for passing the hydraulic fluid from said cavity to said enlarged portion of said cavity in front of said chuck such that as the hydraulic pressure is exerted said chuck is thereby forced rearwardly against the pipe; hydraulic means for providing the hydraulic fluid under pressure to said cavity; dummy block means secured at said rear end of said cavity and in sealing engagement therewith and having a front portion thereof extending into said cavity for engaging pipe and an aperture extending from a rear portion through to a front portion thereof so as to admit the hydraulic fluid into said cavity, said front portion having a smaller cross-sectional area than said rear portion such that upon the hydraulic fluid being supplied to said cavity the resultant pressure upon said rear portion causes said dummy block to move toward said front end of said cavity; said cavity has at least one bulging configuration therein, a bleed pipe extending within said cavity and without through said aperture of said dummy block, and said bleed pipe curving upwardly within said cavity proximate said bulging configuration.

Claims

1. A bulging apparatus of the type employed to shape a pipe by means of hydraulic fluid under pressure, said apparatus comprising: cavity means having a cavity therein for receiving the pipe and having an enlarged front end and a rear end, said rear end of said cavity closely conformed to the external cylindrical dimensions of the pipe; retaining means, for retaining the pipe at said front end of said cavity, comprising a chuck within said enlarged said front end portion and in sealing engagement with the walls of said cavity such that a portion of said enlarged portion is in front of said chuck and separated thereby from the remainder of said cavity, said chuck is adapted to grasp the pipe such that as the fluid pressure is increased the pipe is forced into greater engagement with said chuck, said chuck having an aperture extending axially therethrough, a stopper extends within said chuck through said chuck aperture, said stopper having an aperture therein for passing the hydraulic fluid from said cavity to said enlarged portion of said cavity in front of said chuck such that as the hydraulic pressure is exerted said chuck is thereby forced rearwardly against the pipe; hydraulic means for providing the hydraulic fluid under pressure to said cavity; dummy block means secured at said rear end of said cavity and in sealing engagement therewith and having a front portion thereof extending into said cavity for engaging pipe and an aperture extending from a rear portion through to a front portion thereof so as to admit the hydraulic fluid into said cavity, said front portion having a smaller cross-sectional area than said rear portion such that upon the hydraulic fluid being supplied to said cavity the resultant pressure upon said rear portion causes said dummy block to move toward said front end of said cavity; said cavity has at least one bulging configuration therein, a bleed pipe extending within said cavity and without through said aperture of said dummy block, and said bleed pipe curving upwardly within said cavity proximate said bulging configuration.