U.S. patent number 3,698,281 [Application Number 05/015,032] was granted by the patent office on 1972-10-17 for explosive system.
This patent grant is currently assigned to Lockheed Aircraft Corporation. Invention is credited to Oscar E. Brandt, Joseph G. Harris.
United States Patent |
3,698,281 |
Brandt , et al. |
October 17, 1972 |
EXPLOSIVE SYSTEM
Abstract
A steel tube having a flattened or oval cross section contains a
pair of explosive cores. A sheath of pliable material such as
silicone rubber surrounds and holds the core separated from each
other and generally centered with respect to the steel tube. The
rubber (1) protects the explosive cores from environmental
temperature changes, and (2) absorbs the shock of detonation such
that one of the cores may be detonated while the other remains
undetonated as a reserve for redundancy of the system. Upon
detonation of an explosive core, the steel tube expands from the
flattened or oval cross section to a circular cross section;
whereupon a pair of doublers enclosing the tube are fractured and
separated along a weakened section underlying a notch or groove
which extends longitudinally along a doubler joint and along the
steel tube.
Inventors: |
Brandt; Oscar E. (Saratoga,
CA), Harris; Joseph G. (Dallas, TX) |
Assignee: |
Lockheed Aircraft Corporation
(Burbank, CA)
|
Family
ID: |
21769179 |
Appl.
No.: |
05/015,032 |
Filed: |
February 27, 1970 |
Current U.S.
Class: |
89/1.14;
102/378 |
Current CPC
Class: |
C06C
5/06 (20130101); F42B 15/38 (20130101) |
Current International
Class: |
C06C
5/00 (20060101); C06C 5/06 (20060101); F42D
5/00 (20060101); F42D 5/045 (20060101); F42B
15/38 (20060101); F42B 15/00 (20060101); F42b
001/00 () |
Field of
Search: |
;102/49.5,22-24
;89/1B,1.5F |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Engle; Samuel W.
Claims
What is claimed is:
1. A low shock explosive system comprising:
a separation member including an elongated plate with a rupturable
weakened section;
an expandable metal tubular member;
means for closely confining said tubular member adjacent to the
weakened section of the separation member in the path of expansion
of said tubular member,
said tubular member being elongaged in one dimension in
cross-section;
a pair of explosive cores continuously spaced apart in said
elongage dimension and positioned within the cavity formed by said
tubular member and extending continuously through said tubular
member;
a thermal insulating and shock absorbing material surrounding both
said explosive cores and encased within and substantially filling
the cavity formed by the tubular member,
said material continuously separating said explosive cores and
preventing cross-detonation therebetween;
and means for separately detonating the explosive cores so that
gaseous detonation products expand the tubular member while being
contained thereby and so that the tubular member will expand
against and rupture the separation member.
2. A low shock explosive system in accordance with claim 1 wherein
the separation member comprises two generally planar and parallel
doublers fastened together with the tubular member there between,
each doubler being an elongated strip and having flange parts along
each edge and central part connecting the flanges, said flanges
being fastened together and adapted to hold a structural part to be
separated therebetween, said central parts being offset from each
other to provide sufficient space to contain the tubular member in
an initial oval configuration, said central part of each doubler
having a weakened section extending longitudinally to provide a
line for rupture and separation when the explosive core is
detonated and the tubular member expands from the oval
configuration to a circular configuration.
3. A low shock explosive system in accordance with claim 2 wherein
the weakened section of the doubler comprises a relatively thin
section of material which underlies a notch formed in each doubler,
said notch being centered in the offset central part midway between
the edge flanges.
4. A low shock explosive system in accordance with claim 2 further
comprising a plurality of straps encircling the tubular member
between the doublers and fastened to the flanges on one side of the
doublers, said straps being operable to hold the tubular member to
one side of the doubler after detonation of the explosive core and
after the doublers have ruptured and separated in two parts.
5. A low shock explosive system in accordance with claim 1 further
comprising a detonator assembly attached to the end of the tubular
member for initiating detonation of the explosive cores, said
detonator assembly containing two electrically actuable detonators,
each of the explosive cores having an end extending to a respective
detonator.
6. A low shock explosive system in accordance with claim 5 wherein
the detonator assembly includes a metal plate to which an end of
the tubular member is attached, and wherein the explosive cores
entrend through a hole in the metal plate to the detonator.
7. A low shock explosive system in accordance with claim 5 wherein
two detonation assemblies are provided, one detonation assembly
being attached to each end of the tubular member whereby the
explosive cores may be detonated simultaneously from both ends.
Description
BACKGROUND OF THE INVENTION
This invention relates to an explosive system capable of totally
confining the products of explosion; and more particularly this
invention provides an explosive separation system which will remain
operative in a wide range of environmental temperatures and which
will separate the parts with a minimum of shock.
Heretofore, elongated cords or ropes of explosives have been
utilized in many types of ordnance devices as well as in missile
and satellite separation systems. U.S. Pat. No. 3,373,686 granted
to J. W. Blain and A. B. Leaman on Mar. 19, 1968, describes an
explosive separation system wherein a core of explosive material is
detonated within a radially expandable sheath. The sheath initially
encloses the explosive core with a small cross section, and after
detonation, the sheath in an expanded cross section continues to
contain the gaseous products of the explosion to prevent
contamination of the surrounding region.
The configuration described by U.S. Pat. No. 3,373,686 is
successful in a limited range of temperatures. Should the ambient
temperatures vary greatly above or below a normal room temperature,
the configuration will burst or shatter and release contaminants
into the surrounding space. In contrast, the instant invention
provides a configuration which will remain intact and confine all
products of detonation and other contaminants over a temperature
range from -300.degree. F to approximately 400.degree. or
500.degree. F.
In explosive systems, it is desirable to have a high degree of
reliability. One method for achieving good reliability is through
the use of redundancy in the systems. In the event that one part or
system fails to function properly, a redundant part or redundant
system may provide a back up protection to assure that the
particular function is performed and that the overall operation of
the ordnance device or missile or space vehicle is not impaired.
One method for providing a redundancy is to simultaneously detonate
both ends of an explosive cord or explosive core. If the explosive
core is defective at one point, this redundancy will provide a
proper operation of the system since the two detonations moving
from both ends will traverse the entire length of the core and will
meet at the defective point. This type of redundancy would fail if
there were two or more defective points in the explosive core such
that two detonations traveling from the ends would be blocked at
different points leaving a segment undetonated and with the parts
not completely separated. A further redundancy may be desirable to
permit a second detonation in the event that the first detonation
is not complete.
It is an object of this invention to provide an improved explosive
system wherein more than one explosive core is used within a single
steel tube or expandable sheath and wherein the explosive cores are
held apart from each other by a shock absorbing material such that
the detonation of one core will not cause detonation of the other
core.
It is a further object to provide an improved explosive system for
separation of parts with a minimum of shock imparted to the parts,
and more particularly it is an object to surround the explosive
core(s) with a shock absorbing material within an expandable tube,
such that the tube is expanded principally by the gaseous pressure
of the products of the explosion and also by shock waves from the
explosion.
The ambient or environmental temperatures may vary considerably for
ordnance devices or missile or space vehicles, and it is another
object of this invention to provide an improved explosive system
which will be operative over a wide range of environmental
temperature. More particularly, it is an object to encase the
explosive core(s) in a thermal insulating and shock absorbing
material such that the explosive core(s) will be protected from
both external shock and from temperature extremes to remain
functional over an extended time period.
SUMMARY OF THE INVENTION
According to a preferred embodiment of the invention, the explosive
system comprises an expandable tubular member, for example, an oval
or flattened stainless steel tube, positioned against a separation
member. The expandable member contains a shock absorbing material
such as silicone rubber having two separated cavities to receive
cores of an explosive material. In the completed assembly, the
cores are encased and held separated from each other by the shock
absorbing material which fills the expandable tubular member. Upon
detonation of the explosive core, gaseous detonation products
expand the tubular member against and rupture the separation
member, with the detonation products being contained by the tubular
member which upon expansion remains continuous, that is, does not
rupture.
DESCRIPTION OF THE DRAWING
The various features and advantages of this invention will become
apparent upon consideration of the following description taken in
connection with the accompanying drawing of the preferred
embodiment of this invention. The views of the drawing are as
follows:
FIG. 1 is a plane view of the explosive separation system of this
invention;
FIG. 2 is a section along the line 2--2 of FIG. 1 showing in cross
section the steel tube with the explosive cores and rubber sheath
therein;
FIG. 3A and 3B are similar sections along the line 3--3 of FIG. 1
wherein FIG. 3A is a cross section of the assembly before
detonation and separation, and FIG. 3B is a cross section after the
detonation of one of the explosive cores and during the separation
of parts; and
FIG. 4 is a section along the line 4--4 of FIG. 1 showing a
detonator assembly in cross section.
DESCRIPTION OF THE PREFERRED EMBODIMENT
As shown in FIGS. 1 and 3A, two parts or bulkheads 11 and 12 are
connected together by doubler members 13 and 14. The edges of the
bulkheads 11 and 12 are sandwiched between the doublers which are
fastened together with means such as bolts 15. The doublers are
elongated strips or plates of aluminum or other material and may be
generally flat or planar as illustrated, or may be of a special
shape and configuration required by a missile, space vehicle or any
other structure which is to be explosively separated. The doublers
may comprise two side or edge flanges 16 and 17, with a connecting
central part 18 which is offset with respect to the side flanges.
When the two doublers 13 and 14 are assembled together with the
bulkhead parts 11 and 12, the offset centers provide a space
therebetween for containing a stainless steel tube 19.
As shown in FIGS. 2 and 3A, the steel tube 19 is initially in an
oval or flattened configuration, and is dimensioned to nearly fill
the space between the offset central parts 18 of the doublers 13
and 14. A groove or notch 21 is formed in the doubler members 13
and 14, and extends longitudinally intermediately between the
flanges. The section of material underlying the groove 21 is
thinner, and therefore weaker, than the other parts of the doubler.
Thus, it may be appreciated that the doubler is formed with a
weakened central section which is more easily breakable than other
parts of the assembly. When the steel tube 19 is expected to a
circular configuration as shown in FIG. 3B, the central parts of
the doubler members 13 and 14 are forced outwardly, and each
doubler will rupture or break along the weakened section underlying
the groove 21. With the doublers ruptured as shown, the parts 11
and 12 are separated and are free to move apart from each
other.
The stainless steel tube 19, as shown in FIG. 2, is formed
generally in an oval shape with two spaced apart flat sides and two
semicircular or otherwise rounded edges. A sheath of silicone
rubber 22 or other suitable shock absorbing and thermal insulating
material is shaped to substantially fill the cavity within the
stainless steel tube 19. The rubber sheath 22 contains two
cylindrical holes or cavities containing explosive cores 23 and 24.
The silicone rubber sheath 22 holds the two cores 23 and 24
approximately centered with respect to the stainless steel tube 19
and spaced apart from each other.
The silicone rubber sheath performs several functions. Firstly, the
sheath supports and holds the explosive cores in proper positions,
separated from each other and generally centered in the assembly.
Secondly, the silicone rubber, as a thermal insulator, protects the
explosive cores from sudden temperature variations through which
the components of a missile or space craft may pass. Thirdly, the
shock absorbing qualities of the rubber will protect the cores from
external shock to which a missile may be subjected during launching
and during subsequent operations of rocket engines, etc. And
fourthly, the shock of detonation of an explosive core is
minimized, such that the second explosive core will not be
detonated from the shock waves of the detonation of the first
explosive core, and such that a minimum shock will be imparted to
surrounding parts such as the bulkheads 11 and 12.
As shown in FIG. 1, two detonator blocks 25 and 26 are welded or
otherwise attached to the stainless steel tube 19. The ends of the
rubber sheath 22 are split apart or bifurcated, such that the two
cores 23 and 24 are each extended to a position in spaced relation
to a separate detonating fuse 27, 28, 29 and 30. As shown in FIG.
4, the ends of the explosive cores 23 and 24 are extended into
close proximity with the ends of the detonator devices 27 and 28.
The detonator devices 27 and 28 are of a commercially available
type which may be screwed into a threaded opening and will
constitute a plug therein. These devices may be detonated
electrically from control circuitry not shown.
Since each end of each explosive core 23 and 24 may be separately
detonated, a redundancy is provided to improve the reliability of
the overall system. In operation, one of the explosive cores 23 may
be detonated simultaneously at both ends thereof by the detonators
27 and 29. Obviously, if one of the detonators 27 or 29 failed to
operate, the core would be detonated by the other, and the
detonation would travel the length of the core to effect the
desired separation of parts. Thus, the simultaneous detonation of
both ends of an explosive core insures a proper operation of the
system even though one of the detonators may malfunction. In the
event that there is a break in the explosive core 23, the
simultaneous detonation of both ends thereof will insure a proper
operation of the system, since the two detonations would, together,
traverse the entire length of the core -- from each end toward the
break point.
The second explosive core 24 provides a further reliability in the
system in the form of a back-up protection. Thus, if the detonation
of the first core 23 failed or was not complete, the second core 24
could be detonated. In practice, the control circuitry extends
through an electrical disconnect junction which would be
disconnected and separated when the parts 11 and 12 were separated.
The control circuitry will provide a second electrical impulse to
cause detonation of the back-up core 24 in 600 to 1,000
milliseconds subsequent to the detonation of the primary core 23.
If during this time interval, the first detonation is successful
and a separation of parts is effected; then the electrical
disconnect will be pulled apart; and the second electrical impulse
will not reach the detonator devices 28 and 30, to initiate the
second detonation. On the other hand, should the detonation of the
first explosive core 23 by faulty; the separation of parts 11 and
12 will not be effected, and the electrical disconnect junction
will remain intact such that the second electrical impulse will
indeed be transmitted to the detonator devices 28 and 30 for the
detonation of the back-up core 24.
As shown in FIG. 3B, the detonation of the first explosive core
will cause the stainless steel tube 19 to expand to a circular
configuration or cross section. The expansion of the steel tube 19,
deforms the central parts of the doubler members 13 and 14, and
ruptures the weakened sections underlying the longitudinal groove
or notch 21. Since the silicone rubber sheath 22 absorbs much of
the shock from the explosive, the principle force causing expansion
of the steel tube 19 is the high pressure front generated within
the tube by the gaseous products of the explosion. As shown in FIG.
3B, the silicone rubber sheath may be ruptured at various points
leaving cracks and fissures in the vicinity of the explosion or the
position of the core 23 which was consumed by the detonation. The
expansion of the rubber sheath 22 and of the steel tube 19 does not
detonate the back-up core 24, which remains encased in silicone
rubber as shown in FIG. 3B.
When the doubler members 13 and 14 break as shown by FIG. 3B, the
parts 11 and 12 are no longer held together, and presumably there
will be an immediate separation with the bulkhead or part 11 moving
to the left (in FIG. 3B), and the bulkhead or part 12 moving to the
right. The stainless steel tube, containing the unused explosive
core 24 and containing the products of the explosion must not be
allowed to fall out of the ruptured cavity between the doublers to
become a loose part, free from both the parts 11 and 12. Therefore,
bands or straps 32 encircle the steel tube 19 at periodic intervals
as shown in FIG. 1 and are fastened to one side only of the doubler
assembly. As shown in FIG. 1, 3A and 3B a convenient method for
attachment is to extend the ends of each strap under the flange
side of the doubler member with a bolt extending therethrough.
These bands 32 may be formed of a ductile material such as soft
steel which is flexible and capable of expansion as the steel tube
19 expands, such that the bands or straps 32 will not break as the
doubler breaks and the parts separate. Ordinarily the bands 32
should be attached to that side of the doubler connected to the
part which is to be discarded after separation. Thus, for example,
the part 11 may be a portion of a satelite or space vehicle, and
the part 12 may be of an early stage rocket engine. After the
rocket engine has completed its burn and imparted its thrust to the
space vehicle, it will be separated and discarded. Similarly, after
the steel tube 19 has expanded and has performed its function, it
will likewise be discarded. By strapping the steel tube 19 to the
side connected with the part 12 which is to be discarded, the tube
with the unused explosive core 24, will likewise be discarded from
the still useful part 11 of the space vehicle. The detonator blocks
at each end of the tube may be bolted or otherwise attached to the
same part as that to which the straps are attached to provide a
rigid support for the discarded assembly.
The explosive separation system of this invention provides a
reliable means for separating parts with a minimum shock imparted
to surrounding structures. The stainless steel tube contains the
gaseous products of the explosion after the detonation and
separation of the parts which thereby protects other parts and
components of the assembly from contamination of the explosive
gases. Because of the thermal insulating and shock absorbing
qualities of the rubber sheath, the explosive cores are protected
from damage due to environment temperature change and due to
external shock. These features enhance the reliability of the
system, and the reliability is further enhanced by the redundancy
provided by a second or back-up explosive core, which need not be
detonated at the same time of the detonation of the first or
primary core; but may be held in reserve for later time if
needed.
* * * * *