Explosive tubing swager

[57] ABSTRACT

A non-rupturable spool and an explosive cartridge formed therewith useful for swaging tubing. An explosive charge is contained within the spool and a transfer media, such as rubber, is placed over the spool to form the cartridge. The cartridge is inserted into a tube and the charge is detonated which swages the tube against a sleeve or die.

Claims, 2 Drawing Figures

<img file="US3661004A_D0001.tif" />

PATENTEDMAY 9 ig?2

3,661,004

SHEET 1 OF 2

<img file="US3661004A_D0002.tif" />

FIG. I

INVENTOR

John T M. Lee Donald P Keathley

<img file="US3661004A_D0003.tif" />

ATTORNEY

PATENTEDMAY 9 1972

3,661,004

SHEET 2 OF 2

<img file="US3661004A_D0004.tif" />

FIG. 2

INVENTOR

John T M. Lee Donald P Keathley

<img file="US3661004A_D0005.tif" />

ATTORNEY

3,661,004

EXPLOSIVE TUBING SWAGER

SUMMARY OF THE INVENTION

This invention relates to a spool and an explosive cartridge useful for swaging tubing.

BACKGROUND OF THE INVENTION

A common method of removably attaching one section of tubing to another is to affix a sleeve to the end of the tubing. The tube and sleeve can then be attached to various fittings.

Until now, it has been very difficult to affix a sleeve to a tube with a suitable seal, without damaging or weakening the tubing, and with sufficient strength to pass certain tensile and flexural tests.

ADVANTAGES OF THE INVENTION

We have invented a device for swaging tubing into a sleeve which is easy to operate, completely portable, and free of maintenance problems. A uniform swage of great tensile strength is produced. Although our device employs an explosive, there is little or no fragmentation even when it is fired completely uncontained when the metal of the spool is properly selected. When fired in the tube, no gases or debris are admitted into the tube, thus leaving the tube uncontaminated.

DESCRIPTION OF THE INVENTION

The accompanying cross-sectional drawings show the cartridge of this invention positioned in a tube;

FIG. 1 shows the cartridge prior to firing and

FIG. 2 shows the cartridge after firing.

In FIGS. 1 and 2 a split die 1 made in two pieces, only one of which is shown in the drawing, and a circular die 2 are assembled over a restraining member, here shown as sleeve 3. The internal surfaces of the dies exactly fit the contours of sleeve 3. The circular die and the split die are held securely together with collar 4. The tubing 5 to be swaged is inserted as shown in FIG. 1 until it touches stop 6 of die 2.

The cartridge 7 is then inserted into the tubing as shown. A spool 8 forms part of the cartridge and has a head portion 9, a middle portion 10, and an end portion 11, which has been relieved, here shown by bevel 12. A transfer medium, here shown as a piece of rubber tubing 13, substantially fills the space between middle portion 10 and the tubing 5 and is confined by head and end portions 9 and 11, respectively. Sealing rings 14 and IS help to confine the rubber tubing during the explosion. Situated within middle portion 10 and extending into head portion 9 is a well 16 containing explosive charge 17. The well and charge preferably extend only slightly past the area to be swaged; thus, there is a solid middle portion 18 which, through inertia and physical strength, retains the explosion. Head portion 9 consists of a cap 19 which is threaded onto flange 20 creating a void 21 in which the gases produced by the explosion can expand. If self-containment is not required, the cartridge may be vented to the outside of the head of the spool. The charge is fired by means of an initiator, here shown as a percussion primer 22 which has been sealed to cap 19 with sealing compound 23. A firing block 24 is preferably firmly held against the head of the spool to confine the gases released by the explosion. Percussion primer 22 is fired by striking firing pn 25. As shown in FIG. 2, when charge 17 fires, the force of the explosion passes through transfer medium 13 and deforms tubing 15 into all the contours of sleeve 3. The cartridge is then removed and the die disassembled.

The die generally acts as an anvil to prevent the deformation of the sleeve. Although it may have many possible designs, it is usually designed for rapid assembly and disassembly. The split die of the drawing, for example, is easily removed; the circular die was used to prevent marks which could result from using a die in several sections.

The term “restraining member” is meant to include a die which is removed after the explosion and which merely impresses a deformation on the tubing. However, generally the cartridge of this invention will be used with a “sleeve” which remains affixed to the tubing after the explosion.

The sleeve will generally be metallic, although plastics may be suitable for some purposes. The inside of the sleeve is generally convoluted or grooved to optimize its grip on the tubing.

The tube, which need not be round although it usually is, may be of almost any size and is made of a metal sufficiently ductile to be swaged. “Tube” includes tubes closed at one end to form a cup.

The transfer medium must be substantially non-compressible and is preferably a non-sticky, easily-removable substance. It is preferably made from an elastomer such as rubber, polyurethane, or silicone but could also be a fluid such as water or oil, a quasi-fluid such as powdered glass or sand, or a substance which melts under heat or pressure to produce a fluid. It should substantially fill the space between the middle portion of the spool and the tubing. It should also be at least as long as the portion of the tubing which will be swaged and at least as thick as the depth of the swage to ensure a complete swage.

The spool should be of sufficient strength not to rupture during the explosion when in place in the tube so that the tube is not contaminated. The middle portion must therefore be sufficiently ductile to expand to the degree necessary to swage, yet be strong enough not to rupture under the force of the explosion; steel and aluminum are examples of suitable materials. The head and end portions confine the transfer medium. The end portion is preferably relieved to make it easier to remove the cartridge after the explosion.

The charge contained within the middle portion may be of greater or lesser length than the length of the swage, but it is preferably about the same length. A longer charge unnecessarily increases the problems of confining the explosion and a shorter charge may not give a complete swage. The amount of charge used will, of course, depend upon such variables as the material and thickness of the tube and spool, the extent of the swage, and the type of charge.

The charge is preferably a high explosive such as lead azide, PETN, lead styphnate, RDX, or tetryl; but a low explosive such as a propellant or a metal/metal oxidant may be suitable in cases where not much power is needed. It is preferable that the charge be divided into two portions, a primary explosive at the top portion of the well and a secondary explosive at the base of the well so that a high detonation rate is built up as the explosion progresses to the base of the well. Generally, a primary explosive is one which is initiated by fire such as lead azide, while a secondary explosive is initiated by a shock wave such as RDX.

The charge may be fired by a variety of methods such as with a mechanical primer, for example a percussion primer or a stab primer, or it may be heated with a laser, a flame, or a hotwire, or it may be fired with an electro-explosive initiator such as an electric match. A percussion primer is the preferred firing means.