U.S. patent number 3,782,283 [Application Number 05/169,272] was granted by the patent office on 1974-01-01 for defined disintegration of the casing of an explosive element.
This patent grant is currently assigned to Dynamit Nobel Aktiengesellschaft. Invention is credited to Paul Lingens, Gerhard Martin.
United States Patent |
3,782,283 |
Lingens , et al. |
January 1, 1974 |
DEFINED DISINTEGRATION OF THE CASING OF AN EXPLOSIVE ELEMENT
Abstract
An explosive device and processing for causing, upon detonation,
the defined disintegration of the casing of the explosive device.
This result can be achieved directly by providing cavities in the
explosive charge of the device which conduct the high velocity gas
flow generated during the reaction of the explosive to
predetermined points along the casing. Preferably the explosive
charge has a central bore which connects radially extending gaps.
Alternatively, a defined disintegration can be obtained indirectly
by including cavities in the explosive charge of the device which
are subdivided into chambers by either explosive or inert
materials. Finally, a fuze trail of explosive wires can be
incorporated into the explosive charge to yield the same effect.
Moreover, the explosive charge can be employed as a primer charge
and disposed inside a main charge which, in turn, is enclosed by a
casing.
Inventors: |
Lingens; Paul (Leverkusen,
DT), Martin; Gerhard (Troisdorf, DT) |
Assignee: |
Dynamit Nobel
Aktiengesellschaft (Troisdorf, DT)
|
Family
ID: |
5779044 |
Appl.
No.: |
05/169,272 |
Filed: |
August 5, 1971 |
Foreign Application Priority Data
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|
|
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Aug 6, 1970 [DT] |
|
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P 20 39 131.5 |
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Current U.S.
Class: |
102/322; 102/314;
102/491 |
Current CPC
Class: |
F42B
1/00 (20130101) |
Current International
Class: |
F42B
1/00 (20060101); F42d 001/00 (); F42d 001/04 () |
Field of
Search: |
;102/22-24,28,28EB,DIG.2,67 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Pendegrass; Verlin R.
Attorney, Agent or Firm: Craig, Antonelli & Hill
Claims
We claim:
1. A device for disintegrating a casing into defined splinters
comprising a fragmentable casing and means within said casing for
producing fragments of a substantially predetermined size range,
said means including an explosive charge having at least one cavity
or gap arranged within said explosive charge so that, upon
detonation of said explosive charge, the high velocity and density
gas flow generated therein provides for defined disintegration of
said fragmentable casing to producing fragments of said
substantially predetermined size range.
2. The explosive device of claim 1 wherein said at least one cavity
or gap includes a plurality of damming-up points for said gas flow,
spaced at defined intervals.
3. The explosive device of claim 1 wherein said explosive charge
includes a bore running therethrough.
4. The explosive device of claim 3 wherein said bore is divided
into a plurality of defined chambers by a plurality of
partitions.
5. The explosive device of claim 4 wherein said partitions comprise
an explosive material.
6. The explosive device of claim 4 wherein said partitions comprise
a non-explosive material.
7. The explosive device of claim 3 wherein passageways or gaps are
arranged at defined intervals extending outwardly from said
bore.
8. The explosive device of claim 7 wherein said enclosing casing is
in direct contact with said explosive charge and said passageways
or gaps extend between said bore and said casing.
9. The explosive device of claim 8 wherein said passageways or gaps
are conically-flared.
10. The explosive device of claim 8 wherein the sides of each of
said passageways or gaps are substantially parallel.
11. The explosive device of claim 8 wherein said passageways or
gaps are filled by explosively-inert materials.
12. The explosive device of claim 8 wherein said casing is
tubular-shaped and said explosive charge comprises a plurality of
substantially identical annular elements consecutively spaced from
each other.
13. The explosive device of claim 1 wherein said at least one
cavity or gap is lined with an explosively-inert material.
14. The explosive device of claim 1 wherein said explosive charge
is a primer charge and said explosive device further comprises a
main explosive charge positioned between said primer charge and
said enclosing casing.
15. The explosive device of claim 14 wherein said at least one
cavity or gap is a bore including damming-points therein for said
gas flow.
16. The explosive device of claim 14 wherein said at least one
cavity or gap encloses a fuze train of explosive wires.
17. The explosive device of claim 1 wherein said at least one
cavity or gap encloses a fuze train of explosive wires.
18. The explosive device of claim 1 wherein said explosive charge
includes a plurality of outwardly-extending gaps spaced at a
defined interval.
19. The explosive device of claim 18 wherein said explosive charge
comprises a plurality of substantially identical
consecutively-spaced explosive elements.
20. The explosive device of claim 19 wherein said gaps are filled
by an explosively inert material.
21. The explosive device of claim 1 wherein said device is
constructed to produce casing fragments having a maximum dimension
of less than about 100 mm.
22. The explosive device of claim 21 wherein said fragments have a
maximum dimension of less than about 40 mm.
23. The explosive device of claim 1, wherein the enclosing casing
is a pipe having substantially the same wall thickness along the
extent thereof and is formed of a material capable of producing
fragments for piercing an object.
24. The explosive device of claim 23, wherein said material forming
said enclosing casing is one of iron and steel.
25. A device for disintegrating a casing into defined splinters
comprising a fragmentable casing and means within said casing for
producing fragments of a substantially predetermined size range,
said means including an explosive charge and a fuze train of
explosive wires disposed within said explosive charge and arranged
so that upon detonation of said explosive charge by said fuze train
defined disintegration of said fragmentable casing with the
production of fragments of substantially the predetermined size
range results.
26. A process for disintegrating a fragmentable casing into defined
splinters comprising the steps of providing an explosive charge
within the fragmentable casing, forming gaps or cavities within the
explosive charge in such a manner that upon detonation of the
explosive charge the casing is disintegrated into fragments of a
substantially predetermined size range.
27. The process of claim 26, including arranging the gaps or
cavities to conduct the high velocity and density gas flow
occurring during detonation to predetermined points at the
casing.
28. The process of claim 26, further comprising the step of
positioning a main explosive between the explosive charge and the
casing and arranging the gaps or cavities to conduct the high
velocity and density gas flow occurring during detonation to
predetermined points at the main explosive.
29. The process of claim 26, further comprising the step of
disposing a fuze train of explosive wires within at least one of
the cavities.
Description
BACKGROUND OF THE INVENTION
This invention relates to the defined disintegration or
fragmentation of the casing of an explosive element.
In solid explosive elements, the disintegration of the casing is
caused by the shock wave and the explosion-produced gas pressure
associated with progressing detonation front. The disintegration of
the casing necessarily occurs in a random manner. In addition to
small fragments or splinters, in many cases undesirable, large
fragments result. Thus, the mass of the individual fragments varies
within a wide range. Attempts have been made to divide the casing
into segments or preformed fragments by reducing the wall thickness
at specific points, in order to obtain defined fragments upon
disintegration of the casing. However, such process has the
disadvantage that it unduly complicates the manufacture of the
casing. Moreover, the desired strength of the casing is often
impaired thereby.
SUMMARY OF THE INVENTION
It has now been found, surprisingly, that these disadvantages can
be eliminated by providing that the gas flow of high velocity and
high energy density occurring during the reaction of the explosive
in cavities, chambers, gaps and/or fissures be conducted to the
casing and/or to an explosive, and/or that fuze or primer trains of
explosive wires be arranged in the explosive element.
The gas flow of high velocity is generated in cavities in the
explosive, which cavities have any desired geometric, symmetrical
as well as asymmetrical cross sections, or irregular boundaries.
The cross sections can vary continuously or discontinuously over
the length or depth of the cavities or gaps. For the defined
disintegration of the casing, the gas flow of high velocity and
high energy content can be utilized, firstly in a direct manner
and/or, secondly, in an indirect manner.
In the direct process, the gas flow proper is allowed to be
effective on the casing by, for example, providing gaps or fissures
in the explosive. Due to the high velocity of the gas flow, a
dynamic gas pressure is built up extremely rapidly at the
predetermined points of the casing, resulting in a high compressive
stress on the casing at the respective points. At these places,
there then occurs a preferred rupturing of the casing. If such
preferred points are arranged at predetermined intervals in the
direction of the progression of the detonation, defined fragments
are formed which do not exceed the length of the respective
intervals. Thus, the maximum splinter size can be adjusted over a
wide range. In the direct use of the gas flow, the gap width can be
fixed with the aid of an inert material (metals or nonmetals which
do not explode). The cavities in the explosive can also be lined
with an inert material (metals or nonmetals).
In the indirect process, gas currents of high velocity and energy
density occurring in perforated explosive charges are surprisingly
employable for disintegrating the casing into defined splinters.
According to this embodiment, a defined disintegration of the
casing is unexpectedly obtained primarily by a discontinuity in the
chronological stress on the casing. It is unexpected, since
disintegration, in addition to being affected by the casing
material, depends first of all on the detonation pressure, i.e., on
the chemical composition and density of the explosive. In order to
attain a discontinuity in the chronological stress (stress per unit
time) on the casing, the cavities serving for conducting the gas
currents are subdivided into chambers. The chamber walls can
consist of an explosive or inert material. The gas flow is dammed
up at the chamber wall, which can also form an angle with the
direction of propagation of the flow. At the points of dammed-up
gas, the surrounding explosive is ignited before the detonation
front in the explosive charge arrives. The new detonation front is
propagated radially and results, upon striking the casing, in the
rupturing thereof before the detonation front within the explosive
element has reached this point. The maximum size of the fragments
depends on the length of the chamber. In the subdivision of the
cavity into chambers, a gas jet (high velocity gas flow) is formed
successively in each chamber which again results in the advance
ignition of the surrounding explosive. In this manner, a defined
disintegration of the casing is obtained. In large cross sectional
explosive charges, it is advantageous to arrange several parallel
cavities or one cavity with, for example, an annular cross section,
subdivided into chambers.
The combination of the direct and indirect utilization of a gas jet
of high velocity and high energy density has a very advantageous
effect on a defined disintegration of the casing. Various
possibilities of the combination will be explained hereinafter in
the examples.
It was furthermore found that the use of a fuze train of explosive
wires results in a defined disintegration of the casing. The fuze
train consists of alternating sections of a thick wire and a thin
wire of the same length or of different lengths; see, in this
connection, German Pat. No. P 16 46 348.2. By ignition of the
train, the thin wire sections undergo an explosive conversion
igniting the surrounding explosive. The thick wire sections which
do not explode correspond, in this process, to the chamber length
in the above-mentioned bores and therefore to the maximum size of
the fragments. It is also possible to combine the use of the fuze
train with explosive wires with the use of the gas flow of high
velocity and energy in predetermined cavities and/or gaps. The
utilization of a fuze train thus corresponds to the indirect
method.
By the use of the gas jet and/or a fuze train of explosive wires, a
defined disintegration of the casing is attained, i.e., the
formation of small fragments of high velocity exhibiting great
piercing power. The process of the present invention represents a
simple and economical way for producing defined splinters of the
casing of explosive elements. In the manufacture of large explosive
elements, it is often advantageous to provide primer rods (also
curved or other shapes) within the explosive charge. Explosives and
cavities or fuze trains of explosive wires can be disposed in the
primer rods. The ignition of the explosive element by such primer
rods, which progresses intermittently in the manner previously
indicated, results in the formation of prematurely produced
detonation fronts in the direction toward the casing. Accordingly,
defined disintegration of the casings of the explosive elements
occurs.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be explained in greater detail below with
reference to various embodiments of explosive elements constructed
to produce defined disintegration of their casing taken in
conjunction with the drawings wherein the same reference numerals
are used in different figures to indicate like parts.
FIG. 1 is a cross-sectional view of an explosive element with a
casing and an internal bore according to the invention.
FIGS. 2-6 show cross sections of explosive elements with various
arrangements of filled and empty cavities and/or inert partitions
according to the invention.
FIG. 7 illustrates an X-ray photograph of a prior art iron pipe
during the disintegration into fragments, wherein the iron pipe was
completely filled with explosive.
FIG. 8 represents an X-ray flash photograph of the disintegration
of an iron pipe according to the invention wherein an explosive
column was arranged which was subdivided by partitions into five
individual parts, and which had an axial bore.
FIG. 9 shows the splinter impacts in an aluminum plate caused by a
prior art iron pipe which was completely filled with explosive.
FIG. 10 shows the various splinter zones produced by fragments
stemming from an iron pipe according to the invention which was
filled with an explosive column subdivided into sections by
partitions.
DETAILED DESCRIPTION
The explosive elements illustrated in FIGS. 1-6 having a casing 1
filled with an explosive 3. This explosive is subdivided by bores 6
(FIGS. 1-5), partitions 4 (FIG. 1) of explosive or partitions 7 of
inert material (FIG. 2) inserted in the bore 6, filled or unfilled
gaps 8 (FIGS. 3 and 6), or conical flared portions 10 (FIGS. 4 and
5), so that the gas flow of high velocity and energy density is
conducted to the casing 1 or an explosive. Initiator charge 2 is
included to ignite explosive 3.
EXAMPLE 1
Three explosive charges ("Composition B" which is an explosive
containing 39.5 percent by weight of trinitrotoluene, 59.5 percent
by weight of cyclotrimethylenetrinitramine and 1 percent by weight
of wax) were disposed in a unilaterally sealed iron pipe 1 (length,
450 mm.; inside diameter, 34 mm.; outside diameter, 51 mm.).
Ignition was effected by means of a blasting cap No. 8 (aluminum
cap with primer pellet, a primary charge of 0.3 g. of lead
tricinate and a secondary charge of 0.8 g. of tetryl) and a
penthrite pressed charge 2 of 36 g. at the open end of the pipe.
When the pipe 1 was filled completely with the explosive 3, i.e.,
without any cavities or gaps, fragments were produced during the
detonative conversion of the explosive 3 which had a length of up
to 300 mm. and ranged as low as 50 mm. In contrast thereto, when
the charge was provided with an axial bore 6 having a diameter of
10 mm., which was subdivided into chambers 5 of a length of 90 mm.
by partitions 4 of explosive having a thickness of 17 mm. (FIG. 1),
fragments were obtained upon detonation of only a length of up to
100 mm. The fragment lengths were, in this case, almost uniformly
distributed over magnitudes of between 20 - 100 mm. Also, a
reduction in the width of the fragments approximately to one-half
the values for the filled pipe occurred. It can thus be seen that
the lengths of the fragments at worst barely exceed the lengths of
the chambers.
Example 2
In the following experiments, cylindrical explosive columns 3 of
"Composition B" were brought to a detonative conversion in armor
steel pipes having inside and outside diameters, 16 mm. and 18.4
mm., respectively, with pipe lengths of 140 and 280 mm.,
respectively, by means of a pressed penthrite charge 2 of 18 g.
with a blasting cap No. 8 inserted therein, at one end. The
distribution of the fragments and the size thereof were determined
with the aid of the piercing sites produced by the detonation in an
aluminum plate disposed at a distance of 250 mm. The manner in
which the steel pipes disintegrated was detected by X-ray flash
photography.
In order to show the influence of an axial bore 6 in the explosive
column 3, explosive columns with or without a bore were fired. The
bore 6 was, in some experiments, filled with an inert material
(silver steel rods), in order to obtain the same amount of
explosive as a basis for the various experimental arrangements.
A further modification of the experiment resided in subdividing the
explosive column 3 with or without an axial bore 6, into several
adjoining or specifically spaced-apart explosive elements of the
same length. In this connection, the bore was also filled with an
inert material 7 in a portion of the cases. (See FIG. 2.)
In the arrangements of the explosive columns 3 in the steel pipe 1
according to this example as set forth hereinafter, the maximum
fragment sizes were in the following ranges;
a. Continuous explosive column without axial bore:
60 - 70 mm. (reference or control standard).
b. Continuous explosive column with axial bore filled with silver
steel: 60 - 70 mm. (reference standard).
c. Continuous explosive column with an unfilled axial bore: 60 - 70
mm. (reference standard).
d. Continuous explosive column 3, as shown in FIG. 2, with axial
bore 6, wherein the latter was subdivided, by partitions 4 of
explosive having a thickness of 9.5 mm, into chambers of a length
of 16 mm. (indirect method): 15 - 20 mm.
e. Experimental arrangement as in (d) wherein the length of the
chamber was 40 mm.: 35 - 40 mm.
f. Explosive column 3, as shown in FIG. 3, with an axial bore 6
subdivided, by gaps 8 filled with 2 mm. thick inert PVC-ring disks,
into adjoining bodies having a length of 25 mm. (direct and
indirect method): 15 - 20 mm.
g. Explosive column as in (f), but with empty gaps 8, wherein the
spacing of the individual explosive bodies was 1 mm.: 15 - 20
mm.
h. Explosive column, as shown in FIG. 3, with a bore 6 subdivided
by empty gaps 8 of 1 mm. between elements of a length of 15 mm.:
10- 15 mm.
i. Explosive column 3, according to FIGS. 4 and 5, having elements
of a length of 25 mm. with an axial bore 6. At the end of each
element, the bore was provided with a conically flaring portion 10
(direct and indirect method): 15 - 20 mm.
j. Explosive column 3 without a bore, as shown in FIG. 6,
subdivided by filled gaps 8 of 2 mm. thick inert PVC-ring disks
into adjoining explosive elements of 25 mm. (direct method): 25
.gtoreq. 30 mm.
k. Explosive column as in (j), wherein the spacing of the
individual explosive elements from each other was 1 mm.: 20 - 25
mm.
In experiments (d) - (k) which exhibit various embodiments of the
invention, the controlled disintegration of explosive casings into
splinters of a defined size is clearly demonstrated. In contrast,
reference examples (a) through (c) representative of the prior art,
yield splinters having undefined sizes including undesirably large
fragments.
Due to the premature rupturing of the casing in certain zones of
explosive devices according to the invention, fragments are flung
outwardly in defined splinter rings. This premature rupturing is
shown by the X-ray flash photograph (FIG. 8). An iron pipe filled
with an explosive in the normal fashion (FIG. 7) evidences no such
rupturing. The same effect is demonstrated by splinter impacts on
aluminum plates. In FIG. 10, which corresponds to FIG. 8, the
various splinter zones (delineated by lines 11) are clearly
apparent, as well as the smallness of the fragments. By comparison
the plate of FIG. 9, which shows the splinters of an
explosive-filled iron pipe, includes extremely large fragments
distributed over an unzoned area.
Example 3
A steel pipe, having an inside diameter of 160 mm., a wall
thickness of 4.5 mm., and a length of 150 mm., was filled with
"Composition B", including an axial bore of 16 mm. A rod made of
"Composition B" serving as the primer rod, without or with an axial
bore of a diameter of 4 mm., was inserted in the bore in various
experimental arrangements. The ignition of the rod was effected by
a pressed charge of penthrite of 18 g., inserted in front of the
rod, with a blasting cap No. 8 included therein. In order to
determine the length of the fragments of the casings of the
explosive elements during detonative conversions in the various
experimental arrangements, the fragments were captured in wooden
planks at some distance from the explosive object. The experiments
resulted in the following maximum splinter sizes:
a. Primer rod without bore: 100 - 140 mm.
b. Primer rod with continuous bore: 90 - 130 mm.
c. Primer rod with continuous bore, wherein the latter was
subdivided by a partition of explosive of a thickness of 10 mm.
into two chambers of a length of 65 mm. (indirect method): 50 - 70
mm.
d. Primer rod with a continuous bore, wherein the latter was
subdivided by partitions of explosive of a thickness of 10 mm. into
three chambers of a length of 40 mm. (indirect method): 35 - 40
mm.
This example demonstrates that the idea of this invention of a
predetermined disintegration of the casing of an explosive element
into fragments of a defined size can also be realized in case of
explosive elements of a larger cross section, by the introduction
of a primer rod of a certain design into the axial bore of such an
explosive element. Such primer rods can also exhibit an envelope
consisting of a metal or a nonmetal, the wall thickness of which
envelope does not impair the effect on which the present invention
is based.
Example 4
Steel armor pipes having an internal diameter of 25.5 mm., an
external diameter of 28.4 mm. and a length of 320 mm., filled with
"Composition B," were axially detonated with primer rods with a
diameter of 12 mm. having a primer (or fuze) train of explosive
wires incorporated therein. The following fragment lengths were
observed
a. Six 50 mm. nonexplosive wire sections alternated with five 3 mm.
explosive wire sections:
fragment lengths, 20 - 50 mm.
b. Fourteen 20 mm. nonexplosive wire sections alternated with 13 3
mm. explosive wire sections:
fragment lengths, 8 - 20 mm.
The explosive surrounding the fuze train consisted of sintered
penthrite (pentaerythritol tetranitrate) of a low density.
This example shows unequivocally that the casing of an explosive
element can also be disintegrated into fragments of a defined size
of the use of fuze trains of explosive wires within the explosive
element.
It is understood that the embodiments disclosed herein are
susceptible to numerous changes and modifications, as will be
apparent to a person skilled in the art. Accordingly, the present
invention is not limited to the details shown and described herein
but intended to cover any such changes and modifications within the
scope of the invention.
* * * * *