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Патент USA US2403488

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July 9, 1945-
2,403,488
T. F. BENNETT
EXPLQSIVE CARTRIDGE ASSEMBLY
Filed May 1, 1945
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ATTORNEY
' ‘2,403,488
_ Patented July 9,1946
UNITED STATES PATENT OFFICE
2,403,488
EXFLOSIVE CARTRIDGE ASSEMBLY .
Thomas F. Bennett, 'J‘oplin,v Mo., asllgnor .to
Hercules Powder Company, Wilmlngtolabel.
a corporation of Delaware
Application May 1, 1945, Serial No. 591,304
4‘
> (C1. 1132-4-24)
1
.
2
‘
'
A preferred embodiment of the invention has
been chosen for purposes of illustration and de
scription and is shown in the accompanying
drawing which forms a part of the speci?cation,
wherein reference numerals refer to like parts
This invention relates to an explosive cartridge
assembly and more particularly to an improve
ment in a threaded explosive assembly of the
type used in geophysical prospecting.
In U. 8. Patent 2,317,354 to Bennett, there is
wherever they occur.
In the drawing:
disclosed an explosive cartridge assembly com
prising a plurality of explosive cartridges con
nected in end-to-end abutting relationship by a
.
'
Fig. 1 is an elevational view of a threaded car
tridge and sleeve with the cartridge provided with
engage the cartridges. With such an assembly, 10 an additional friction thread, illustrating the ap-
plurality of connecting sleeves which threadedly
plication of the invention;
the cartridges and sleeves are supplied in a stand
I
Fig. 2 is a fragmentary, sectional view taken
ard unit which is readily built up at the site of
on line 2—2 of Fig._ 1, illustrating the sleeve '
use by simply screwing the units together to form
thread;
an explosive column of desired length. However,
3 is a fragmentary, sectional view taken
the desired length is sometimes of considerable 1c. onFig.
line 3-3 of Fig. 1, illustrating the cartridge
magnitude, thereby placing a considerable ten
thread and the friction thread; and
sile stress on the entire column, which stress is
Fig. 4 is a fragmentary, sectional view taken translated into a torsional force due to the pitch
on line 4-4 of Fig. 1, illustrating in detail the
of the threaded sleeves and cartridges. The re
application ‘of the invention with the cartridge
sultant e?ect of this torsional force is a tend
and sleeve engaged.
.
ency for a sect-ion lot the column to rotate and
Referring now to the drawing in detail, an
come apart. -That is, the cartridge and sleeve
explosive cartridge I is provided with a wrapper
having the least frictional resistance in threaded
2 which has an external spiral thread 3 through
relationship actually can become unscrewed and
out its length. The cartridge l threade'dly en- the portion of the column therebelow may be
gages .a sleeve 4 which is substantially the same
dropped during lowering of the column into a ver
length as the cartridge. The sleeve 4 is provided
tical borehole.
with an internal thread 5 as illustrated in Fig. 2.
One of the objects of the present invention is
s
to prevent rotation and consequent disengage
In addition to the spiral thread 3, the wrapper
suspended.
threads 3 and 6, respectively. The wrapping 9
is adhesively ailixed to an inner wrapper H which
is adjacent the explosive l3.
2 has an external, spiral, friction thread 5 ,
ment of sections of a threaded explosive column. 30 throughout
its length. The friction thread 6 is
Another object is to provide a friction thread
disposed relative to the thread 3 so as to fric
which prevents rotation and consequent disen
tionally engage the interior surface of the sleeve
gagement of sections of such a column.
lasillustratedinFig.4.
'
'
Still another object is to provide a friction
thread on a threaded explosive cartridge to fric 35 With particular reference to Figs. 2, 3 and 4,.
the sleeve 4 comprises an ‘outer wrapping 1 ad
tionally engage threaded connecting sleeves for
hesively amxed to an inner wrapping 8 which is
the cartridge and thereby prevent sections of a
spaced to form the thread 5. The cartridge
column of such sleeves and cartridges from be
- wrapper 2 comprises an outer wrapping 9 which
coming unscrewed .duelto torsional forces cre
ated by the weight of the column when vertically 40 covers ‘the cords l0 and II, which form the
Other objects of the invention will appear here
inafter, the novel features and combinations be
ing set forth in the appended claims.
Generally described, the present invention com
prises a threaded explosive assembly composed
of threaded cartridges and threaded sleeves pro
vided with a friction thread on each cartridge in
An example of the operation of the invention ‘
45 is given for building up an assembly of cartridges '
and sleeves. An explosive cartridge such as I is
screwed into a sleeve such as 4 until approxi
matelylhalf of its length extends from the sleeve.
Another sleeve is screwed upon the length of
frictional engagement with its respective sleeves,
cartridge extending from the ?rst sleeve until
which friction thread permits screwing of the 50 the
two sleeves are in tight abutting relationship.
sleeves upon the cartridges to form an explosive
‘Another
cartridge is then screwed into the ex
assembly, but prevents the unscrewing of sec
tending sleeve until the two cartridges are in
tions of the assembly by torsional forces created
tight abutting relationship. This procedure is
by the weight of the assembly or column when
continued until a rigid, explosive column of the
vertically suspended.
2,408,488
3
.
desired length, and accordingly weight of ex
plosive, is obtained. The entire column is then
raised vertically and lowered into a vertical bore
hole. The weight of the assembly of cartridges
'
4
the outer wrapping of the sleeve; however, other
cellulosic'material or derivatives thereof may be
utilized. Chipboard or equivalent material is pre~
ferred as the material for the inner wrapping of
the sleeve which when wound in spaced rela
and sleeves constituting the column creates a
tionship forms the sleeve thread. Chipboard of
torsional force on the column which tends to
unscrew‘the cartridges and sleeves. That is, the
about 30 point or approximately 0.03 inch thick
cartridge and sleeve which have the least fric
has been found suitable in conjunction with the
cartridge thread heretofore described to with
tional resistance afforded by their threaded rela
tionship may become unscrewed and that portion 10 stand the loads imposed on columns under prac
of the’ column therebelow may actually drop into
tical conditions.
The principle of the present invention is ap
the borehole. However, the friction thread on
the cartridge greatly increases the frictional re
plicable to the interconnection of threaded ex
sistance as between the cartridge and sleeve by
plosive cartridges for any use and, while the above
being in frictional engagement with the interior 15 description refers particularly to geophysical
of the sleeve. This frictional engagement per
‘prospecting, the invention may be utilized in any
mits the cartridge to be screwed into the sleeve,
type of blasting work where a long column of ex
but has‘ su?icient resistance to prevent any sec
plosive is needed. Accordingly, gelatin explosives,
tion of the column from unscrewing due to the
ammonium nitrate explosives, black powder, or
torsional forces created by weight.
any other type of blasting explosive may consti
The preferred method of manufacturing the
tute the cartridge charge and use of any of
cartridge wrappers and sleeves of the present
these explosives in conjunction with the present
invention is by spiral winding. This method of
invention is contemplated, regardless of their
particular ?eld of use.
manufacture is economical and permits forma
tion of the necessary threads on the sleeves and
cartridge wrappers in a facile manner, since these
threads are wound on the respective parts at the
The particular utility of the present invention
has been found to reside in conjunction with the
cartridge and sleeve assembly disclosed in U. S.
Patent 2,317,354 to Bennett, in which the sleeves
and cartridges are disclosed as being substantially
use of strip, sheet material, such as paper or other 30 the same length. With this arrangement, it has
cellulosic material. Materials of this kind have
been found possible to obtain su?icient frictional
a considerable range of dimensional stability.
resistance by utilizing the friction thread in ac
Moreover, spiral wrapping machines and con
cordance with the present invention, even when
volute wrapping machines, particularly where
assembling cartridges in the order of 3 inches
adhesives are employed, are not capable of manu 35 in diameter and greater.
facturing cellulosic tubes within close tolerances.
To build up a rigid column of explosive the
The range of dimensional stability inherent in a
sleeves should be in end-to-end abutting relation
cellulosic material plus the best tolerance limits
ship as well as the explosive cartridges. When the
obtainable in machines of the class described does
sleeves and cartridges are of the same length in such
not permit a close ?t between the sleeve thread 40 a column, the sleeves are contiguous to the car
and cartridge thread. When a close ?t was at
tridges throughout the length of the column with
tempted, it was found impossible, in a consider
the exception of each end of the column which has
able percentage of cases, to manually screw the
extending therefrom a half of sleeve and a half
cartridges and sleeves together. As a result of
of cartridge, respectively. In view of this, it is
this, it has been found necessary‘ to provide a
contemplated within the purview of the invention
loose ?t between the sleeve thread and cartridge
that the sleeves may be half the length of the
thread. This loose ?t, of course, has a low factor
cartridge or any other multiple length of the car
of frictional resistance. The friction thread in
tridge, the only requirement being that they be
accordance with the present invention augments
adapted to be screwed in end-to-end abutting re
60
the entire frictional resistance between the car
lationship over the cartridge and provide a suf
tridge and sleeve to an extent sufficient to resist
?cient extension from each end of the cartridge
the torsional forces heretofore described, but yet
to permit positive engagement of additional car
same pitch used for the spiral winding. How
ever, this-method of manufacture requires the
permits manual assembly of a. column of ex
tridges.
plosive cartridges and sleeves in a facile manner.
It is further contemplated within the purview
Paper is preferred as the material for the car 55 of this invention that more than one friction
tridge wrapper; however, other cellulosic ma
terial or derivatives thereof may be utilized.
Paper twine is preferred as the cord material for
forming the threads; however, hemp. or cotton
thread may be utilized on each cartridge to give
the desired frictional resistance between the car
tridge and its sleeves. It will be evident that ‘
limitations are imposed on the size of friction
cord material may be used. For cartridges from 60 thread which may be utilized by the clearance
about 2 inches to about 4 inches in diameter and
between the cartridge and interior surface of the
from about 16 inches to about 30 inches in length,
sleeve. If the friction thread is too large, the
it has been found that a cord in the order of
cartridge cannot be conveniently screwed into
0.06 inch diameter covered with an outer wrap
ping of manila paper in the order of a 64# paper 65 the sleeve. It is preferable to use an increased
number of small friction threads rather than a
will give a cartridge thread of su?lcient strength
single large friction thread to obtain an increased
to withstand the loads practically imposed on
amount of resistance.
columns built up of such cartridges. It has also
It will be seen that the present invention pro
been found that a cord in the order of 0.017 inch
diameter covered with paper of the above weight 70 vides for the attainment of the objects heretofore
will give the desired frictional resistance when
set forth in a simple, convenient, and economical
the clearance between the cartridge wrapper and
manner, and that the invention makes possible
the interior of the sleeve is in the order of 0.015
the ready provision of a rigid column of inter
inch.
connected explosive cartridges which can be sub
Paper is likewise preferred as the material for 75 jected to a variety of uses and remain intact.
2,408,488
5
rate cartridges as they are placed into a borehole
and extending throughout the length of the car
tridge in frictional engagement with the interior
surface of each sleeve in threaded engagement
and likewise prevents a separation of cartridges
with said cartridge.
The invention further positively prevents dirt,
mud, or debris from getting between the sepa
in a column with attendant loss of propagation.
‘
3. A threaded explosive assembly comprising a
Other advantages and applications of the inven
tion than those heretofore set forth will be ap
plurality of threaded explosive cartridges held in
end-to-end abutting relationship by a plurality
parent to those skilled in the art.
of threaded sleeves in end-to-end abutting rela
tionship, and a friction thread disposed on each
What I claim and desire to protect by Letters
Patent is:
‘
10 cartridge and extending throughout the length
of the cartridge in frictional engagement with
1. A threaded explosive assembly comprising a
the interior surface of each sleeve in threaded
plurality of threaded explosive cartridges held in
engagement with said cartridge.
end-to-end abutting relationship by a plurality
4. A threaded ‘explosive assembly comprising a
of threaded sleeves in end-to-end abutting re
lationship, and at least one friction thread dis 16 plurality of threaded explosive cartridges held
in end-to-end abutting relationship by a plural
posed on each cartridge and extending through
ity of threaded sleeves in end-to-end abutting re
out the length of the cartridge in frictional en
lationship, the said cartridges and sleeves being
gagement with the interior surface of each sleeve
of substantially the same length, and a friction
in threaded engagement with said cartridge.
2. A threaded explosive assembly comprising 20 thread disposed on- each cartridge and extending
throughout the length of the cartridge in fric
a plurality of threaded explosive cartridges held
tional engagement with the interior surface of
in end-to-end abutting relationship by a plural
each sleeve in threaded engagement with said
ity of threaded sleeves in end-to-end abutting re
lationship, the said cartridges and sleeves being _ cartridge.
THOMAS F. BENNETT.
of substantially the same length, and at least
one friction thread disposed on each cartridge
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