NASA CASE NO. LAEL152 -6_4_IPRINT FIG. J__

_3EICE

The invention disclosed in this document resulted from research in aeronautical

and space activities performed under programs of the National Aeronautics and Space

Administration. The invention is owned by NASA and is, therefore, available for

licensing in accordance with the patent licensing regulations applicable to U.S.

Government-owned inventions (37 CFR 404.1 et seA.).

To encourage commercial utilization of NASA-owned inventions, it is NASA

policy to grant licenses to commercial concerns.

nonexclusive licensing to promote competition and

Although NASA encourages

achieve the widest possible

utilization, NASA will provide the necessary incentive to the licensee to achieve early

practical application of the invention.

Address informational requests for this invention to the Technology

Applications Team, NASA Langley Research Center, Code 200, Hampton, Virginia

23681-0001.

Address applications for license to the Patent Counsel Office, Mail Stop 212,

3 Langley Boulevard, Hampton, Virginia 23681-0001.

Serial No.: 08/637,335

Filed: 04/04/96 LaRC
NASA Case No. LAR I 5264-1 -SB 

EXPLOSIVE SPOT JOINING OF METALS 

An apparatus and method are provided to achieve wire splicing using an 

explosive joining process. The apparatus consists of a prebend, U-shaped strap 

of metal that slides over prepositioned wires. A standoff means separates the 

wires from the strap before joining. An adhesive means holds two ribbon 

explosives in position centered over the U-shaped strap. A detonating means 

connects to the ribbon explosives. The process involves spreading strands of 

each wire to be joined into a flat plane. The process then requires alternating 

each strand in alignment to form a mesh-like arrangement with an overlapped 

area. The strap slides over the strands of the wires, and the standoff means is 

positioned between the two surfaces. The detonating means then initiates the 

ribbon explosives that drive the strap to accomplish a high velocity, angular 

collision between the mating surfaces. This collision creates surface melts and 

collision bonding resulting in electron-sharing linkups. 

The novelty of the present invention lies in the ability to explosively join a 

plurality of metal components of similar or dissimilar composition, which 

minimizes the amount of explosive required, reduces damaging pressure waves, 

noise nuisance, and damage to surrounding structures. 

Inventors: Laurence J. Bement Ronnie B. Perry 

Address: 21 Brandon Road 139 Eberly Terrace 

New~ort News. VA 23601 Ham~ton. VA 23669 

ss: 

Employer: NASA LaRC 

Initial Evaluator: Melvin H. Lucy 

LESC 

Serial No.: 081637,335 

Filed: April 4, 1996 
14__13 - _ F-12

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LAR 15264-1 -1- PATENT APPLICATION

EXPLOSIVE SPOT JOINING OF METALS

OdgirLo_the Invention

5 The invention described herein was made in the performance of

work under a NASA Contract and is subject to the provisions of Section

305 of the National Aeronautics and Space Act of 1958, as amended,

Public Law 85-568(72 Stat. 435; 42 USC 2457).

10 Background of th_ednvention

1_ Eield o f___._ention

15

20

This invention generally relates to metal fusion bonding using

explosive energy. More specifically, the invention is an apparatus and

method for explosively joining, i.e. welding and cladding, metals of

similar or dissimilar composition in small-areas or "spots," whereby a

sealing bulkhead prevents contamination of the surfaces of the metals to

be joined.

2. De scdption_fJ_m_B_el ated Art

25

Since the 1960s, metal bond fusion using explosive energy, or

"explosive joining," has been developed to provide an efficient and

versatile means of bonding metals which are otherwise difficult or

impossible to weld and/or clad by conventional, non-explosive means. In

particular, explosive joining is uniquely and especially suitable for joining

metals of dissimilar metallurgical composition whose melting points are

incompatible with conventional welding; for joining thin sheets of metal
LAR 15264-1 -2- PATENT APPLICATION

or metal wiring which might be damaged by the heat of conventional

welding; for joining metals in areas made inaccessible by bulky

conventional welding equipment, e.g. the assembly of structures in

space; and for joining metals, e.g. titanium or aluminum, which require ti

5 me and a high degree of skill to weld due to the unique physical

properties of the metals.

The explosive joining process produces a high velocity, angular

collision between the surfaces of the metal components to be joined

which causes the formation of interatomic, electron-sharing linkups at the

10 point of contact between the metal components. Upon detonation of the

explosives, the metal components to be joined are impelled together with

sufficient force to produce metallurgical bonds which are impossible to

achieve by any other known process. This process is comparatively

simple and can be performed by relatively unskilled personnel.

15 Consequently, explosive joining is particularly useful in its unique

applications and relative simplicity.

Previous methods of explosive joining have addressed

incorporating an inverted "V" standoff interface on one or a plurality of

metal components to be joined, in order to maximize bonding efficiency.

20 For example, U.S. Patent No. 4,708,280 by Bement describes an

inverted "V" standoff, machined into the outer surface of either or both

of the metal tubes to be joined, as an alternate to the preferred

embodiment. Hence, the Bement patent reveals art which purports to

limit use to joining two metal tubes.

25 Previous methods of explosive joining also have addressed

problems associated with degradation of the bonding surface, i.e. the

surface bond area, between the metal components to be joined. Such

degradation typically results after the initial detonation of the explosives

when very-fine, high-density particles contained in the explosives invade
LAR 1

5

10

5264-1 -3- PATENT APPLICATION

the standoff space between the metal components to be joined before

the explosive energy has propagated through the metal components to

initiate the angular collisions between the metal components. For

example, U.S. Patent No. 5,318,213 by Strickland et al. addresses one

aspect of surface degradation, i.e. "air burning," by shielding the metal

components to be joined in an "envelope made of deformable material."

Typically, air burning is manifested when very-fine, high-density solid

particles from the explosives, e.g. carbon, which became airborne after

the initial detonation, ignite. Thus, the Strickland patent reveals art

which embodies a means of minimizing surface bond degradation caused

by very-fine, airborne particles which ignite in the air space between the

metal components to be joined.

15

2O

25

Summary of the Invention

The present invention is an apparatus and process for explosively

joining a plurality of metal components of similar or dissimilar

composition.

An object of the present invention is to provide a means of

explosively joining a plurality of metal components, wherein an inverted

"V" standoff interface is machined onto or formed into a plurality of

metal components to be joined, to maximize bonding efficiency.

Another object of the present invention is to provide a means of

explosively joining a plurality of metal components, wherein a sealing

bulkhead is employed, to minimize contamination of the bonding surface,

and, hence, a degradation in the size and strength of the bond area.

A further object of the present invention is to provide a means of

explosively joining a plurality of metal components which minimizes the

amount of explosive required.
LAR 15264-1 -4- PATENT APPLICATION

Still another object of the present invention is to provide a means

of explosively joining a plurality of metal components which reduces

damaging pressure waves, noise nuisance, and damage to surrounding

structures.

5 The present invention attains the foregoing and additional objects

by providing an apparatus and process for joining metal components

using explosive energy. While this process is specifically applicable to

explosive cladding and welding of metals, its application is not limited to

those two embodiments. Similarly, this process is particularly useful for

10 joining metal components in small areas or "spots;" however, its

application is not limited to explosive "spot" welding. A "spot" is therein

defined as a bond area that is at least twice the thickness of the thinnest

metal component being joined, in any direction of the surface bonded.

The apparatus consists of a plurality of small metal components to

15 be joined and ribbon explosives. A standoff means, consisting of an

inverted "V" standoff interface machined onto or formed into a plurality

of the metal components, separates the metal bonding surfaces prior to

detonation and is designed to provide maximum joining efficiency. A

sealing means protects the integrity of the bonding surface using a

20 sealing bulkhead which prevents surface contamination by high-velocity

particles released by the detonation. An adhesive means holds a ribbon

explosive in position on each metal component. A detonating means

initiates the ribbon explosives.

The process involves placing the metal components to be joined in

25 any desired orientation. When the metal components are joined with their

axes generally perpendicular to each another, a tab joint is created. When

the metal components are joined along the same axes, i.e. parallel, to

each other, a splice joint is created.

For a splice joint, an inverted "V" standoff is machined onto or
LAR 15264-1 -5- PATENT APPLICATION

formed into a "host" metal component at any desired location. A "host"

metal component is herein defined as a metal component into which

either an inverted "V" standoff, or a sealing bulkhead, or a combination

of the two, is machined or formed. The tip of the inverted "V" is oriented

5 along the same axis of the "host" metal component and generally

perpendicular to the axis of the other metal components. A sealing

bulkhead is also machined onto or formed into the same "host" metal

component so that it is oriented generally perpendicular to the "host"

metal component and therefore along the same axis as the other metal

10 components. The sealing bulkhead is located nearest to the point of

initiation of the explosives so that the explosive energy impacts the

sealing bulkhead before impacting other portions of the metal

components to be joined.

For a tab joint, an inverted "V" standoff is machined onto or

15 formed into a "host" metal component at any desired location. The tip of

the "V" is oriented along the same axis as the "host" metal component.

A sealing bulkhead is machined onto the "host" metal component so that

the sealing bulkhead is located generally perpendicular to the axis of the

"host." The sealing bulkhead is located nearest to the point of initiation

20 of the explosives so that the explosive energy impacts the sealing

bulkhead before impacting other portions of the metal components to be

joined.

For either joint type, ribbon explosives, or, alternately, unconfined

strips of explosives, are fashioned and bonded to the outermost surface

25 of the metal components to be joined. An adhesive means, e.g. doublebacked tape, affixes the ribbon explosives, or, alternately, unconfined

strips of explosives, to the metal components. A detonating means is

mated to the ribbon explosives so that the propagation direction of the

detonation initially impacts the sealing bulkhead. The detonating means is
LAR 15264-1 -6- PATENT APPLICATION

then ignited to effect an explosive joining of the metal components.

Brief Description of thugs

5 FIG. 1 is a cross-sectional view of a "host" metal component for a

splice joint with an inverted "V" interface detail;

FIG. 2 is a plan view of a "host" metal component for a splice joint

with a sealing bulkhead detail;

FIG. 3 is a cross-sectional view of the splice jointing process

10 comprising two metal components whose common axes are parallel to

one another;

FIG. 4 is a plan view of the splice jointing process comprising two

metal components whose common axes are parallel to one another;

FIG. 5 is a cross-sectional view of a "host" metal component for a

15 tab joint with an inverted "V" interface detail;

FIG. 6 is a plan view of a "host" metal component for a tab joint

with a sealing joint detail;

FIG. 7 is a cross-sectional view of the tab jointing process

comprising two metal components whose axes are generally

20 perpendicular to one another; and

FIG. 8 is a plan view of the tab jointing process comprising two

metal components whose axes are generally perpendicular to one

another.

25 De_tion_nf the Preferred EmbBdimeBt

The present invention involves physical processes for explosively

joining a plurality of similar or dissimilar metal components to form a

splice joint 20 or a tab joint 40, depicted in plan view in FIGs. 4 and 8,
LAR 15264-1 -7- PATENT APPLICATION

respectively.

Referring to FIGS. 1 and 2, which, respectively, depict crosssectional and plan views of a "host" metal component 10 for a splice

joint 20, a preferred embodiment of a "host" metal component 10

5 comprises a strip of metal approximately 0.125 inches in thickness 14

and 0.50 in. in width 16. An inverted "V" interface 12 is machined or

formed onto the "host" metal component 10 as a standoff means to

separate the "host" metal component 10 from the receiving metal

component 11, to maximize the efficiency of the high velocity, angular

10 collision necessary to effect the explosive joint. The inverted "V"

interface 12 should be machined or formed onto the "host" metal

component 10 at an approximate angle between 3 and 10 degrees from

the horizontal with the tip of the inverted "V" interface 12 oriented

generally perpendicular to the axis of the "host" metal component 10.

15 The length of the inverted "V" interface 12 should correspond to the

desired splice joint 20 length, with each leg 17 of the inverted "V"

interface 12 approximately one-half the total length of the desired splice

joint 20 length. A sealing bulkhead 13 is also machined or formed onto

the "host" metal component 10 to provide a sealing means, to minimize

20 contamination of the bonded surface between the "host" metal

component 10 and the receiving metal component 11. The sealing

bulkhead 13 should be oriented in the common axis 18 of the "host"

metal component 10. The sealing bulkhead 13 is typically 0.02 in. in

thickness but could be any practical thickness. The length of the sealing

25 bulkhead 13 should extend slightly beyond each leg 17 of the inverted

"V" interface 12.

As shown in the completed assembly of FIGs. 3 and 4, a preferred

embodiment of the present invention for a splice joint 20 comprises a

"host" metal component 10 and a receiving metal component 11 which
LAR 15264-1 -8- PATENT APPLICATION

are placed one atop the other along their common axis 18. The

orientation of the "host" metal component 10 and the receiving metal

component 11 should be such that the tip of the inverted "V" interface

12 is positioned along the receiving metal component 11 at the midpoint

5 of the desired splice joint 20 location.

Referring to FIGs. 5 and 6, which, respectively, depict crosssectional and plan views of a "host" metal component 30 for a tab joint

40. As for the splice joint described above, a preferred embodiment of a

"host" metal component 30 comprises a strip of metal approximately

10 0.125 inches in thickness 34 and 0.50 in. in width 36. An inverted "V"

interface 32 is machined or formed onto the "host" metal component 30

as a standoff means to separate the "host" metal component 30 from the

receiving metal component 31, to maximize the efficiency of the high

velocity, angular collision necessary to effect the explosive joint. The

15 inverted "V" interface 32 should be machined or formed onto the "host"

metal component 30 at an approximate angle between 3 and 10 degrees

from the horizontal with the tip of the inverted "V" interface 32 oriented

generally along the axis 38 of the "host" metal component 30. The

length of the inverted "V" interface 32 should correspond to the bond

20 length desired, with each leg 37 of the inverted "V" interface 32

approximately one-half the total length of the desired bond length. A

sealing bulkhead 33 is also machined or formed onto the "host" metal

component 30 to provide a sealing means, to minimize contamination of

the bonded surface between the "host" metal component 30 and the

25 receiving metal component 31. The sealing bulkhead 33 should be

oriented generally perpendicular to the axis 38 of the "host" metal

component 30. The sealing bulkhead 33 is typically 0.02 in. in thickness

but could be any practical thickness. The length of the sealing bulkhead

33 should be equivalent to the width of the "host" metal component 36.
LAR 15264-1 -9- PATENT APPLICATION

As shown in the completed assembly of FIGs. 7 and 8, a preferred

embodiment of the present invention for a tab joint comprises a "host"

metal component 30 and a receiving metal component 31 which are

placed one atop the other and generally perpendicular to one another.

5 The orientation of the "host" metal component 30 and the receiving

metal component 31 should be such that the tip of the inverted "V"

interface 32 is positioned along the receiving metal component 31 at the

midpoint of the desired tab joint 40 location.

Ribbon explosives 35 should be cut to an appropriate length;

10 bonded to the outer, i.e. non-bonding, surface of the "host" metal

component 30 and the outer surface of the receiving metal component

31; and finally mated to a detonating means (not shown). An appropriate

length of ribbon explosives 35 extends as necessary to allow for

assembly with the detonating means (not shown). The orientation of the

15 ribbon explosives 35 should be generally along the axis 38 of the "host"

metal component 30, to give the sealing bulkhead 33 greatest effect. The

width of the ribbon explosives 35 should approximately equal the length

of the inverted "V" interface 12. To bond the ribbon explosives 35 to the

"host" metal component 30 and the receiving metal component 31, first

20 an adhesive means 39, such as double-back tape, is positioned and

attached to the outer surface over the desired bonding area. The ribbon

explosive 35 is then centered on and pressed into the adhesive means 39

to effect a bond. Preferably, ribbon explosives 35 are placed on both the

"host" metal component 30 and the receiving metal component 31 and n

25 initiated simultaneously to generate symmetrically opposed forces and to

minimize or eliminate offsetting forces generated during explosion of the

ribbon explosives 35. An alternative embodiment, however, would

position the ribbon explosive on only the "host" metal component 30 and

then placing the receiving metal component 31 upon a shock absorbing
LAR 15264-1 -1O- PATENT APPLICATION

means such as an anvil to maximize joining efficiency by reducing

deformations.

The present invention further comprises a detonating means (not

shown) such as a blasting cap mated to the ribbon explosives 15,35. The

5 detonating means (not shown) initiates the ribbon explosives 15,35

which impel the "host" metal component 10,30 and the receiving metal

component 11,31 together under great energy to effect a bonded splice

joint 20 or tab joint 40. Electric blasting caps may be used to initiate the

explosive and require approximately 0.1 joule. Such blasting caps must

10 use electrical shielding, grounding, and fail-safe firing systems.

Alternatively, a number of aerospace approaches for initiation,

such as mechanically actuated percussion primers, explosive transfer

lines, or lasers may serve as a detonating means.

While specific embodiments of the invention have been described

15 herein, they are only exemplary of the novel feature of the invention and

are not exhaustive.

Many variations and modifications of these specific examples will

be readily apparent to those skilled in the art in light of the above

teachings without departing from the scope of the appended claims. This

20 invention may be practiced otherwise than as specifically described

herein.

What is claimed as new and desired to be secured by Letters

Patent of the United States is:
"Page missing from available version"
LAR 15264-1 -17- PATENT APPLICATION

EXPLOSIVESPOT JOINING OF METALS

AbstracLef_ th eJ3Jsclosure

5 The invention is an apparatus and method for wire splicing using

an explosive joining process. The apparatus consists of a prebend, Ushaped strap of metal that slides over prepositioned wires. A standoff

means separates the wires from the strap before joining. An adhesive

means holds two ribbon explosives in position centered over the U10 shaped strap. A detonating means connects to the ribbon explosives. The

process involves spreading strands of each wire to be joined into a flat

plane. The process then requires alternating each strand in alignment to

form a mesh-like arrangement with an overlapped area. The strap slides

over the strands of the wires, and the standoff means is positioned

15 between the two surfaces. The detonating means then initiates the

ribbon explosives that drive the strap to accomplish a high velocity,

angular collision between the mating surfaces. This collision creates

surface melts and collision bonding resulting in electron-sharing linkups.