US3224238A

US3224238A - Explosive-forming apparatus

Info

Publication number: US3224238A
Application number: US305295A
Authority: US
Inventors: Erik K Henricksen
Original assignee: Aerojet General Corp
Current assignee: Aerojet Rocketdyne Inc
Priority date: 1963-08-29
Filing date: 1963-08-29
Publication date: 1965-12-21
Anticipated expiration: 1982-12-21

Description

Dec. 21, 1965 E. K. HENRIKSEN 3,224,238

EXPLOSIVE-FORMING APPARATUS Filed Aug. 29, 1963 INV OR ERIK K. HENR|KSEN g8 By ATTO EY United States Patent 3,224,238 EXPLOSIVE-FORMING APPARATUS Erik K. Henricksen, Downey, Calif., assignor to Aerojet- General Corporation, Azusa, Califl, a corporation of Ohio Filed Aug. 29, 1963, Ser. No. 305,295

10 Claims, (Cl. 72-56),

The present invention relates in general to the art of die-shaping and more particularly to a method of and apparatus for shaping through the use of forcing means such as explosives.

In explosive forming or shaping, the workpiece is positioned in a die which may be immersed in a tank of fluid such as water. An explosive also is immersed which when detonated will bring the workpiece to the desired shape by shock waves transmitted through the liquid driving the workpiece against the die. Gases generated by the detonation of the explosive are free to escape from the die and have no effect on the operation.

When tubular dies are used to form a workpiece to accurate dimensions, it is necessary that the explosive be positioned axially within the die with a high degree of accuracy. Such axial positioning has been difiicult to accomplish, and it is toward removing difliculties in positioning that this invention is directed.

Accordingly, it is an object of this invention to provide a method of and means for positioning an explosive accurately in a tubular die which is both rapid and effective.

It is another object of the invention toprovide a method of and means for such positioning wherein centering of the explosive is accomplished quickly and easily by means external to the explosion chamber.

It is a still further object of the invention to provide a method of and means for accurately positioning an explosive in a tubular die which means may be rapidly operated by unskilled personnel without danger of faulty operation.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

FIG. 1 is a side elevation partly in section of one embodiment of the invention.

FIG. 2. is a section along line 22 in FIG. 1.

FIG. 3 is an end view of a component of the embodiment shown in FIG. 1.

FIG. 4 is a sectional view of a component of an alternate embodiment of the invention.

FIG. 5 is a view partly in section of a companion memher to the component shown in FIG. 4.

FIG. 6 is a view partly in section of components of an alternate embodiment of the invention.

Referring now to FIG. 1, a sectional cylindrical die 10 is shown which includes semi-cylindrical sections 11 and 12, the die 10 configured to form workpiece 16 into desired shape. Several identical sections of similar workpieces may be formed and joined by welding, brazing or other means.

Flanges 13 and 14 may be clamped together by bolts and nuts 15 or by other suitable means. Explosive 17, if it is to form identical sections, must be positioned accurately axially in die 10 and may be a rod of explosive or a length of Primacord or a number of explosive segments positioned end to end. Explosive 17 is suspended generally centrally within die 10 by cords or wires 27'whose ends are secured to die end members 20 and; 21.. End member 20 may be formed as a disc fitting within the end of die 10 for the purpose of accurate centering and having a flange 22 abutting the end surface of the die. The inner face of end member 20 may be formed with an axial recess 23 which has a screwthreaded wall 24. A support retainer comprising a ring 25 having its outer edge screw-threaded to screw into recess 23 is formed with a plurality of slots 26, shown in FIG. 3, extending inwardly from the. center opening of ring 25, the center opening being slightly greater in diameter than the diameter of the explosive or Primacord.

A plurality of extensible means such as cords 27 shown in FIG. 2, with knots at their ends, or headed wires of equal length, are positioned one in each of slots 26 and retained therein by a retaining sleeve 28, shown in FIG.3, having an inner diameter slightly greater than that of the explosive. The outer diameter of sleeve 28 fits snugly within the ring 25. Sleeve 28 is provided with an outwardly projecting flange 29 overlying the end knots of the extensible means 27. The outer face of end member 20 is formed with a center boss 30 axially drilled to closely fit a squib 31 crimped onto the length of explosive 17. A retaining ring 32 screwing onto the outside of hub 30 clamps the length of explosive 17 in position.

The

opposite end members

20, 21 are cut away on opposite sides as shown at 33 in FIG. 2, to facilitate assembly and operation and to provide for the escape of gases generated by the detonation of the explosive 17. Spring clips 34 may be mounted on the ends of the die to initially maintain the

end members

20, 21, in position, the clips, 34 being arranged to permit assembly and rotation of. the end'members.

The support retaining arrangement associated with end member 21 includes a threaded stem 35 which is formed with spline teeth 36 at its inner end to engage with splines 36 at the inner end of an axial bore in end member 21. Slots 37 are cut between the teeth 36 and lead into a peripheral recess 38. The remainder of the stem 35 is threaded. A retaining sleeve 39 is interiorly threaded to screw on the stem 35 to retain end knobs on extensible means or cords 27 in the recess 38.

End member 21 is formed with an outwardly extending central boss 40 drilled to receive stem 35 and is furnished with a stepped end 41. A tightening hand wheel 42 fits on the stepped end 41 and is provided with an axial interiorly threaded bore engaging with the threaded stem 35; When hand-wheel 42 is rotated, stem 35 is moved outwardly stretching tight the cords 27, the spline teeth 36 sliding along the splines 36 cut around the inner end of the hole drilled through boss 40.

When the cords have been stretched tight they may be wound helically around the surface of the rod of explosive by rotating one or both the

end members

20, 21, in the latter case, of course, in opposite directions.

In FIGS. 4 and 5 analternate embodiment of the invention is shown wherein support and positioning of the explosive is eifected through use of a loosely woven fabric sleeve whose end strands are secured to end

members

20 and 21. Explosive 17 is inserted through alternate end member 43 which is formed as a ring and threaded on its outer periphery to screw into the recess 23 shown in FIG. 1. Member 43 is provided with an inwardly extending boss 44 having a peripheral groove 45 to receive a cord 46 by which one end of a loosely woven fabric tube 47 is secured on the boss 44.

The member 48 securing the opposite end of the fabric sleeve 47 includes a threaded stem 49 at itinner end and a projection 58* having a peripheral groove 51 to which the opposite end of sleeve 47' is secured by cord 52 as in FIG; 4. Interposed between the projection 50 and the threaded portion 49 of the member are spline teeth 53 formed to engage with the spline grooves 36 formed at the inner end of the bore in end member 21 as shown in FIG. 2.

Threads 49 will be engaged by the interior thread on hand-wheel 42 as shown in FIG. 1, and since member 47 forms a sheath for the explosive in slack condition, merely stretching the member 47 is sufficient to provide a firm support centralizing the rod of explosive, particularly where the fabric is woven of diagonally arranged threads. Instead of a loosely woven fabric tube 47, a length of rubber tube may be used, which also will contract in diameter when stretched.

FIG. 6 shows a third embodiment of the invention in which the end members of the die are used to support and apply tension to a rod of explosive having formed integral ly with it a surrounding or interwoven grid, net or tube which sustains a diametrical contraction when stretched. The

end members

20 and 21 shown in FIG. 1 are used with only additional member 54 necessary at each end of the die. Member 54 is formed with an axial stub 55 having a bore 56 cylindrical at its outer end and of square cross-section at its inner end, the square cross section of the bore tapering inwardly. The outer surface of stub 55 is screw-threaded as shown at 57 and a hand wheel 58 may be mounted on the threaded section. The center portion of the hub of the hand wheel is drilled out as indicated at 59. A square tubular key 60 tapered at its inner end and slotted so that it may be forced to make a solid connection between the wall of the square section of the hole in end member 54 and a square section of rod 61 of a suitable explosive is tightened by hand wheel 58. A squib 62 pinched onto a short cylindrical end portion of the explosive 61 has a terminal 63 projecting through the center opening in the hand wheel 58.

The rim of the end piece 54, which may be similar in configuration to that of the end members previously described, is provided with a plurality of small holes aligning with axially extending holes drilled into the edge of the die. A small pin 64 may be inserted through a hole in the edge of the end member 54 and into a hole in the die member aligned therewith until it is required to twist the rod of explosive by twisting the end member 54 about the axis of the die. After putting the rod of explosive 61 under the required torsion, the pin 64 may be reinserted to maintain the desired torsion.

Since the die is lowered below the surface of liquid in a tank, combined hoisting lugs 65 and legs 66 (see FIG. 2) are attached to the die to enable it to be positioned in a tank (not shown) either vertically or horizontally as may be required.

In describing operation of the device it will be assumed that the die is supported out of a tank (not shown) and has been assembled by tightening up the bolts and nuts 15 and with

end members

20, 21 removed. The workpiece 16 is then inserted in placed. Cords 27 are then connected to end member 20 by laying them in slots 26 in ring 25, which has been removed from the end member 20, and retained in position by retaining sleeve 28. The loaded ring is then screwed into the recess 23. Threaded stem 35, which has been removed from end member 21, is then connected to the free ends of cords 27 and held in place by screwing sleeve 39 on the threaded stem to retain the knotted end of the cords in the recess 38, and the hand Wheel 42 is screwed off the stem 35. A length of rod (serving as a positioning tool) may then be passed through end member 20 and engaged against the stem 35, the extended cords surrounding the rod. End member 20 is then positioned in the end of the die.

Threaded stem 35 may be readily guided into the axial bore in end member 21, which is in position in the opposite end of the die, the spline teeth 36 entering splines 36' and restricting stem 35 to axial movement relative to end member 21. Spring clips 34 serve to retain the end members in position at this stage of the assembly. The hand wheel is then screwed on the outer end of the threaded stem until in position on the outer end of boss 40 and then tightened up to initially stress the cords or wires 27.

The positioning rod is then withdrawn and the explosive inserted. The explosive is positioned by screwing ring 32 down on squib 31, and may then be firmly gripped in axial alignment by rotating the

end members

20, 21 with respect to one another which has the effect of both wrapping the cords 27 helically around the rod of explosive and further tightening them.

The assembled die with the workpiece and explosive axially aligned is then lowered to a position below the level of the liquid in the tank and conventional procedures are followed in exploding the charge. A similar procedure is followed with respect to the embodiments of FIGS. 4 and 5, sheath 47 being positioned before explosive 17 is inserted within it.

In the modification of the invention shown in FIG. 6, one end of explosive 61 may be mounted in an end member 54 after hand wheel 58 has been slacked back or unscrewed and key 60 knocked out. Key 60 is then replaced and forced into the square bore in the end member 54 by screwing up the hand wheel to force the squared resilient end of key 60 between the squared periphery of the rod 61 and the faces of the square socket in the end member 54. The end member carrying the rod 61 by one end is then inserted in the die and the free end fitted in the center opening in the other end member from which the chuck member and hand wheel have been removed. This end member is then positioned on the end of the die and the chuck member positioned in the socket and firmly seated by screwing up the hand wheel. The rod 61 if explosive may then be put under torsion by twisting one or both of the end members which end members can be retained in position by inserting pin 64 into aligned holes in the edge of the die and end member. Torsion will then shorten, tighten and straighten the rod of explosive axially within the die.

After the explosive has been centered by any of the means shown and described, an electric cable controlled by a make and break switch in the usual manner may be connected to the contact extending from a squib secured on one end of the explosive. The explosive may then be detonated by closing the switch after the die has been positioned in a tank of liquid.

Where it is desired to form workpiece 16 under a vacuum, O-

rings

70 and 71 may be positioned between the workpiece and

end members

20 and 21 to form a vacuum tight seal therebetween. Vacuum fitting 73 is then added to provide a passage through which a vacuum may be created in the space 72 between the outer periphery of workpiece 16 and die 10. Conventional evacuating means, not shown, may then be connected to passage 74 in vacuum fitting 73, and space 72 evacuated.

It will be appreciated that other means than those shown and described may be used to position an explosive within the concept of the invention. For example,

alternate end members

20 and 21 may be used in each embodiment, with those for the embodiment of FIG. 1 being simply end plates with an annular ring of holes accurately positioned in axial alignment with the die, and cords 27 drawn taut through the holes and knotted at the outer surfaces of the plates. Likewise, with respect to the embodiment of FIGS. 4 and 5 where one plate may have the projection 50 and groove 51 shown in FIG. 5 and the other a similar groove on the end of a shaft which is threaded and extends through the outer end plate. The desired tension may then be applied by turning the shaft. Locking in position may be efifected by a lock nut turned over the threads and abutting the outer surface of the plate. In the embodiment of FIG. 6, the alternate end plates would have axially positioned holes through which the integral explosive and support member would project, the portions projecting preferably being square and recured within a clamping member by means of which torsion may be applied.

Also included in the concept of the invention is the use of segments of explosive and segments of spacer material to be inserted in the volume formed by the cords, sheath or other extensible means such that explosive segments may be positioned at desired points within the enclosed volume.

Obviously many modifications and variations of the present invention are possible in the light of, the above teachings. the scope of the appended claims the invention may be practiced otherwise than as specifically described.-

I claim:

1. The method of positioning a uniformly shaped member axially within a uniformly shaped chamber comprising the steps of positioning said member in a sheath whose diameter is reduced when the sheath is stretched, mounting the sheath centrally between opposed end members to said chamber, andstretching the sheath in an axial direction by forces applied exterior to said chamber whereby the sheath diameter is decreased until a desired compression against said member is realized, said compression being exerted radially inwardly so as to simultaneously center said member in said chamber.

2. A device for positioning an elongate body of substantially uniform cross section centrally within an elongate chamber by external application of force comprising a pair of removable end means for substantially enclosing said chamber, sheath means defining a volume sufiicient to freely accommodate said body, said sheath means being susceptible to constriction upon being extended, means for securing one end of said sheath means central- 1y to the inner surface of one of said end means, said other end means having an aperture centrally disposed to accommodate said sheath means, and means extending through said aperture for gripping the other end of and extending said sheath Within said chamber, whereby upon positioning said body in said sheath within said chamber, extenson of said sheath will constrict said sheath against said body and simultaneously center said body within said chamber.

3. Explosive-forming apparatus comprising: a tubular die, a pair of end closure members respectively centered in the opposite ends of the tubular die, at least one of said end closure members being removable from said tubular die, a'rod of explosive material extending axially through said tubular die, strand means secured to said end closure members and arranged to extend around the periphery and along the length of said rod of explosive material to support said rod of explosive material within said tubular die, and means mounted on at least one of said end closure members effective to draw said strand means into taut condition around and bearing against the surface of said rod of explosive material to accurately support said rod of explosive material axially of said tubular die.

4. Explosive-forming apparatus as set forth in claim 3, wherein said strand means comprises a plurality of cords extending between said end closure members.

5. Explosive-forming apparatus as set forth in claim 3, wherein said strand means comprises a loosely woven fabric sleeve defining a sheath extending between said end closure members.

6. Explosive-forming apparatus comprising: a tubular die, a pair of end closure members respectively centered in the opposite ends of the tubular die, at least one of said end closure members being removable from said tubular die, a rod of explosive material extending axially through said tubular die, strand means secured to said end closure members and arranged to extend around the periphery and along the length of said rod of explosive material to support said rod of explosive material within said tubular die, means mounted on at least one of said end closure members effective to draw said strand means into taut condition around and bearing against the surface of said rod of explosive material, and at least one of said end closure members being mounted for rotation on the end of the tubular die with which it is associated so that said taut strand means secured to said end closure members It is therefore to be understood that within may be wound under tension helically around said rod of explosive material upon rotation of said latter one of said end closure members to accurately support said rod of explosive material axially of said tubular die.

7. Explosive-forming apparatus comprising: a tubular die, a pair of end closure members respectively centered in the opposite ends of the tubular die, at least one of said end closure members being removable from said tubular die, a rod of explosive material extending axially through said tubular die, strand means arranged to extend around the periphery and along the length of said rod of explosive material, securing means mounted centrally on one of said end closure members effective to secure one end of said strand means, securing means mounted centrally on the other of said end closure members to which the other end of said strand means is connected, means mounting one of said securing means on said end closure member with which it is associated for guided axial movement to bring said strand means into taut condition around and bearing against the surface of said rod of explosive material when said one securing means is caused to move axially away from the other securing means, and at least one of said end closure members being mounted for rotation on the end of the tubular die with which it is associated so that said taut strand means may be wound helically around the rod of explosive material upon rotation of said latter one of said end closure members to accurately support said rod of explosive material axially of said tubular die.

8. Explosive-forming apparatus comprising: a tubular die, a pair of end closure members respectively disposed at the opposite ends of the tubular die, a rod of explosive material extending axially through said tubular die, means carried by said end closure members to support said rod of explosive material within said tubular die, and at least one of said end closure members being rotatably mounted on said tubular die, whereby rotatio of said one end closure member is effective to operate said supporting means carried thereby to enable said rod of explosive material to be accurately supported axially of said tubular die.

9. Explosive-forming apparatus comprising: a tubular die, a pair of end closure members respectively disposed at the opposite ends of the tubular die, a rod of explosive material extending axially through said tubular die, a plurality of cords carried by said end closure members and extending therebetwee around the periphery and along the length of said rod of explosive material to support said rod of explosive material within said tubular die, and at least one of said end closure members being rotatably mounted on said tubular die, whereby rotation of said one end closure member is effective to wind said plurality of cords helically about said rod of explosive material to enable said rod of explosive material to be accurately supported axially of said tubular die.

10. Explosive-forming apparatus comprising: a tubular die, a pair of end closure members respectively disposed at the opposite ends of the tubular die, a rod of explosive material extending axially through said tubular die, a sheath carried by said end closure members and extending therebetween in surrounding relation to said rod of explosive material to support said rod of explosive material within said tubular die, and means mounted on at least one of said end closure members effective to stretch said sheath for constricting said sheath about said rod of explosive material to enable said rod of explosive material to be accurately supported axially of said tubular die.

References Cited by the Examiner UNITED STATES PATENTS 2,779,279 1/ 1957 Maiwurm 113-44 3,162,709 12/ 1964 Davidson 25-l 18 CHARLES W. LANHAM, Primary Examiner.

Claims

2. A DEVICE FOR POSITIONING AN ELONGATE BODY OF SUBSTANTIALLY UNIFORM CROSS SECTION CENTRALLY WITHIN AN ELONGATE CHAMBER BY EXTERNAL APPLICATION OF FORCE COMPRISING A PAIR OF REMOVABLE END MEANS FOR SUBSTANTIALLY ENCLOSING SAID CHAMBER, SHEATH MEANS DEFINING A VOLUME SUFFICIENT TO FREELY ACCOMMODATE SAID BODY, SAID SHEATH MEANS BEING SUSCEPTIBLE TO CONSTRICTION UPON BEING EXTENDED, MEANS FOR SECURING ONE END OF SAID SHEATH MEANS CENTRALLY TO THE INNER SURFACE OF ONE OF SAID SHEATH MEANS, SAID OTHER END MEANS HAVING AN APERTURE CENTRALLY DISPOSED TO ACCOMMODATE SAID SHEATH MEANS, AND MEANS EXTENDING THROUGH SAID APERTURE FOR GRIPPING THE OTHER END OF AND EXTENDING SAID SHEATH WITHIN SAID CHAMBER, WHEREBY UPON POSITIONING SAID BODY IN SAID SHEATH WITHIN SAID CHAMBER, EXTENSION OF SAID SHEATH WILL CONSTRICT SAID SHEATH AGAINST SAID BODY AND SIMULTANEOUSLY CENTER SAID BODY WITHIN SAID CHAMBER.