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Патент USA US2412581

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. Dec# 17» 1946.
Filed Jan. 22, 1940
2 Sheets-Sheet 1
Dec- 17, Í946»
Filed Jan. 22, 19.40
2 Sheets-Sheet 2
Patented Dec. 17, i946
Daniel D. Huyett and Frank S'. Pollock, Wilming
ton, Del., assignors to Atlas Powder Company,
Wilmington, Del., a corporation of Delaware
Application January 22, 1940, Serial No. 315,094
2 Claims. (Cl. 102--24)
This invention relates to a. sheathing for ex‘.
unitV are. more. or less subject to accidental ex
plosives, which sheath is of the type that. isA em;
plosion, particularly When carried out by auto
ployed- to modify the normal properties of car
matic machinery and are therefore undesirable;v
tridged explosives in various` ways; as for ex.n
Furthermore` separate sheathing manufacturing
ample: the suppression of flame, the reduction of’ » Ul units. required to be installed and maintained at
poisonous fumes, the reduction of smoke,v the
each ofA such» explosive plants tremendously in
reduction of shattering effects, etc. It contem
creases the cost of manufacturing.
plates the provision, as an article of manufac
sheathed explosive structures which are sepa
ture, of an improved unit sheathing structure and
ratelyv fabricated from the explosives by utilizing
the method of making the same.
a rigid> metal sleeve or> cylinder as the interior
The useof explosives such` as dynamite, blast
physical support for the sheath insteadof an ex
ing powder and thelike in mine- operations, par
plosive cartridge are-very expensive to manufac
ticularly in coa-l» mining, is attended by consider
tureA and involve- considerable hazard' inasmuch.
able danger due to the presence of methane orv
as their use would require the insertion` and.
“fire damp” in the passages and chambers of
tamping of the metal into the borehole along'
subterranean mines. Many mine’disasters have
with the explosive.
resulted from ignition of “nre damp” under the
pressure and flame conditions accompanying the
firing of such explosives. As a consequence, it
The foregoing and other disadvantages inher
flame suppressing substance such as a mixture
It is a' primary object of our invention to pro
vide a flame-suppressing unit for explosivesk
ent inthe explosive sheathings heretofore pro
posed have preventedtheir adoption to any,- great
has been proposed to use with the explosive a 20 extentin this country.
of calcium fluoride and sodium chloride; Here
tofore such flame-suppressingr substances have
been utilized either by mixing them with the ex
plosive composition, in which case the mixture
including the salts is formed directly into` ex
plosive cartridges, or by applying the salts asv a
which is more effective than units heretofore
known and in use.
It is also an object of our invention to provide"
a flame-suppressing unit for explosives whichis
not affected by atmospheric conditions during@
protective covering abouta separately fabricated
explosive cartridge. The present invention» re
shipment and storage.
Conversely. it is.- an object of.l our invention to
lates tothislatter type of covering which is' generally knownin the art as a “sheathing” for ex
Vvprovide a hermetically-sealed flame-suppressing.'
unit for explosives which permits the use of ex
tremely hygroscopi'c: substances: otherwise not>
When the name-suppressing salts are used,v in
the form» of a sheathing it is usually necessary to
suppressing media.
susceptible. of' successfulA employment. as flame'
support the salts upon some sort of a carrier as
It is also an object of our invention to provide
the salts, even though slightly agglomerated with
a dama-suppressing uniti for explosives which is
a binder material, are diflicult to cast or mold
construction, permitting manufacture
into a structure having suñicient permanent
at extremely low- costf- by automatic high-speed:
strength to resist the handling to which they are
machinery of known design.
subjected. Since the salts that are suitable for 40
It is also an object of our invention to provide
usel as llame-suppressing substances are usually
ture formed of these salts will disintegrate when
a llame-suppressing“ unit, which though. her
meticallyY sealed against; ingress off atmospheric
moisture may be easily and quickly assembled
the» salts are exposed to the moisture normally .
With the explosive. components at the actual 1o--
present in the atmosphere. Thus, molded, ag
cation-of use.vv
glomerated sheathing units having no inner or
outer carrier or casingl are entirely impractical
and worthless for use With almost all of the> de
sired flame-suppressing compositions which com
Another'object' of'V our invention" is the provision
withk such a llame-suppressingl unit, where neces
markedly hygroscopic in character, any struc-VA
sary, of a means. for inhibiting access of mois'
ture. after complete assembly with the explosive.
Further objects and objects relatingy to details
prise hygroscopic and/or water-soluble ingredi
of constructionand advantages of use will more
Proposed methods which effect the direct for
mation of the llame-suppressing unit about the
definitely appear from the -detailed description to
follow. In general, however, weA accomplish the
explosive cartridge or thepacking of the loose ex
plosive composition directly within the sheathing
objectsV of“ our' invention by using'.> a: cylindrical
shellbody'of any'suîtabl'e material> adapted to be:`
handled in cartridging machines, as for example
of the sheath covered by a protecting cylinder of
waxed paper, paper backed aluminum foil, as
waxed paper.
bestos sheeting, etc.
A preferred type is a
spirally wound, glued paper shell, which is pref
erably coated with Wax after being loaded with
the sheathing composition. This shell carries an
internal, hollow, cylindrical body or lining of
sheathing composition and its ends are closed
Like numerals designate corresponding parts in
all of the figures of .the drawings.
In the drawings, Figs. 1 to 4 and 5 designate a
and sealed to inhibit the entrance of moisture so
.tubular shell made preferably of paper. Both for
reasons of economy and to reduce the quantity
of combustible material, the shell 5 is preferably
formed of a relatively light paper.
This shell carries a cylindrical lining 6 of a
as to protect the said sheathing composition l0
material .that is capable, when surrounding a
(which is usually of a, hygroscopic nature)
cartridge of explosives, of modifying certain of
against moisture damage, at least until the time
its normal characteristics to the extent desired.
for use arrives. The said sheathing composition
For example, the lining 6 may consist of a ñame
may be any suitable non-explosive material or
materials capable of being packed or molded l5 suppressing composition comprising such hygro
within said shell as a cohesive lining of suf
scopic and/or Water soluble inorganic ingredients
ficient strength to resist damage by shocks inci
dental to normal handling and shipment, prior to
its ultimate assembly with a cartridge of explo
as for example sodium chloride, sodium bicar
bonate, ammonium chloride, magnesium carbon
ate, sodium carbonate, magnesium sulphate and
sive. The said end closing means are of such de- 2O the like, for the purpose of suppressing the nor
mal flames `of explosives so as to render them
sign as to provide easy insertion of an explosive
cartridge into the sheath, without physical dam
less likely to ignite inflammable gases and dusts
age to the sheath body.
in mines and tunnels. Y While our invention is not
restricted thereto, most of the desirable sheathing
The end closures of the sheathings are also so
designed :that lthey will permit a plurality of 25 compositions, for various purposes, with which
we are familiar, are of such a nature .that thelr
sheathed explosive cartridges to fit snugly to
require a binder ingredient to impart the neces
gether end to end, with a minimum of space
sary physical strength. As a binding ingredient
and/ or inert covering therebetween, -and into such
for the sheathing composition there may be em
juxtaposition that the propagating explosive wave
will be eiîectively transmitted throughout .the 30 ployed starch, sodium silicate, dextrin, glue, as
bestos fiber, Wood pulp, bagasse fiber, etc. Vari
length of a column of such assemblies.
ous fillers and/or density lowering ingredients
Further, the end closures are designed so that,
may also be used in the sheathing composition, as
if desired, the sheathings may be rendered mois-V
well as ingredients for miscellaneous other pur
ture or Water resistant, after the insertion of .the
explosive cartridge.
3y poses as, for example, bagasse pith, kieselguhr,
chalk, lime, zinc oxide, silica, balsa sawdust, etc.
More specifically, we accomplish the objects of
The sheathing 6 is molded in place in the shell
our invention by the means and methods set
5 preferably while moist with water, and is
forth in the following specification. Non-limiting
tamped to yield a cylindrical body which, when
structures constituting preferred embodiments of
our invention as illustrated in the accompany- 40 dry has considerable strength. The open ended
.tubular shell 5 serves as a mold for the sheathing
ing drawings form a part of this speciñcation in
composition and provides a path for air to pass
through and moisture to escape in the drying
Figure 1 is a longitudinal sectional view of a
operation. In the absence of any moisture to
sheath showing one form, though not necessarily
thepreferred form, of the invention;
45 cause its disintegration, this cylindrical body of
sheathing material, by reason of its arch forma
Figure 2 is a view like Fig. 1, illustrating one
tion and the support provided by the shell 5, will
of lthe end closures punctured and pushed in
resist considerable pressure and stress and may
wardly preparatory to the insertion of a stick or
be shipped in this form and stored for consider
cartridge of explosive, such as for example dyna
5o able periods of time Without breaking down.
The ends of the shell 5 are closed by simple
Figure 2a is a view of the structure of Fig. 1
thin cupped paper wads or Vwebs 1, and in the
showing a cartridge of explosive inserted in the
form of the invention illustrated in Figs. 1 to 4,
sheath, but with a paper disc cemented to the an
the ends of the shell are crimped into engage
nular portion of the crimped wad;
Figure 3 is a View of the structure of Fig. 1 55 ment with the edges of the wads. A coating of
paraffin, indicated at 8, aids in further excluding
showing a cartridge of explosive inserted in the
moisture, and the empty sheathings, consisting
sheath, but with a separate paper disc disposed
of the assembly illustrated in Fig. 1, may be
under and cemented to the segments of the orig
manufactured at one place and shipped to an
inal punctured end closure;
Figure 4 is an end view of the closure of Fig. 1, 60 other for the insertion therein of the sticks of
showing the manner of splitting or puncturing
the end closure or Wad, as in Fig. 2, preparatory `
to inserting the explosive cartridge;
explosive, with the assurance that the sheathing
composition will be found in good condition
whenever the explosive sticks are placed therein,
whether thatbe at a factory or Whether it be in
Figure 5 is a longitudinal sectional view illus
trating a modified form of end closure consisting 65 the mine immediately prior to the use of the
of a simple cupped, thin paper wad, inserted in
When it is desired to insert the stick of ex
the ends of a plain paper cylinder or shell con
taining the sheath, but not crimped;
I plosive, one of the end closures 'l may be entirely
cut out for that purpose, or the end cap may be
Figure 6 is a view like Fig. 5 but illustrating
the explosive cartridge in place and a new paper 70 cut through in any other desired way. For eX
ample, in Fig. 4, we have illustrated the cap 'í
wad cemented in place and supported by the ex
slitted radially at 1a. The points 'lb so created
plosive cartridge; and
- '
may be folded inwardly as in Fig. 2 and the ex
Figure 7 is a longitudinal sectional view of an
other form ofV sheath, one end of which is left .
permanently open, and with the interior surface 7
plosive cartridge inserted into the sheathing.
The web or cap is radially slit across only that
part of its diameter which> covers the` bore oitheî
sheath. 6. Thus` when a stick ofi explosive is;
thrust into the bore of the~ sheath the resultant
pointed ends Tb willfold inwardly along thezinner>
surface of the. sheath and be- bound thereagainst
by the presence of the. stick of explosive, leaving.the unslitted portion of the. web- ory cap still en
gaged with the-shell 5 and drawn over and pro
the;` permanent;~ open-ing, thus> provided. at. any:L
time. and location. desired.
While we. have described thef tubev or' web |25
andthe end-Wadi 'lb asv being ofpaper, itis toi-be:
understood that any equivalent.material,` such asv
paper backed' aluminum foil,- chlorinated. rubber,
regenerated cellulose, celluloseacetate, orthe like>A
may be employed.
tecting the end of sheathing 5. If desired,l after
We are aware. ofI the. fact. that` it has> been pre
the points have been bent inwardly, a disc l‘lla ‘ ~ viously- proposed to. provide sheaths for exploi-I
shown in Fig. 2a can be pasted or otherwiseA se.
sive compositions; comprisingA pre-formed'.` bodies:
cured to the annular portion of thecrimped wad
which. covers the end of the sheathing, thereby
to hold the cartridge of explosive in place. This.
disc could be parafñned or otherwise madey water
The points 7b may also be turned outwardly, a
stick of' dynamite. 9 inserted, a plain paper disc».
lil placed over the end of the stick of dynamite,
as in Fig. 3, and the points 'lli may then be ce
mented down upon the disc lâ. This yields a
closure having its outer edges still engage-d in
the crimp i l, and by dipping the end of the stick
in parañine, a closure is then provided which will
be water-tight even in the presence of water
under pressure. In many instances, it may be
more advantageous to bend the points 'lb down
against the end of the explosive cartridges, then
cement the disc lil over these points rather than
of flame-suppressing material. However,` as' far
as we are aware, wee are the ñrst to utilize a; pre:
formed body' of flame-suppressing; or other' typef
of sheathing composition for explosives„containedz
in a moisture resistant and protective: casing and
wherein` such body> of. sheathing compositi/on` is
in such form as: to; be. capable of, maintaining. its; I
sha-pe andï initial composition during? handling,
transportation and storage, even~ in the: absence
of the explosive; cartridge or any'other'rigid inner
supporting element. in con-junction `with which
itis to be> ultimately used;
The; sheathing structures. of the present inven
tion are particularly adaptable. for use: iny con
junction with the Slo-called “permissible” explo
sives utilized in minesA having; inflammable gasesv
and/or dusts» which> are. likely to become ignited'
in the presence of.' flame, but are not restricted;
under them, and subsequently dip the end of the 30 thereto. It will be.` evident that any> desired type;
of blasting explosive may- beV employed; in; the
stick in paraiìne as hereinbeiore described. If
this method were followed, the disc would neces
sarily be larger in diameter (as disc lüa in Fig.
sheaths of our invention and We may employ
sheathing compositions to modify properties of
2a) to insure a Snug iit inside the crimp.
the blasting explosives, other than flame, as for
In the form of the invention illustrated in Figs. 35 example to reduce smoke, to reduce poisonous
5 and 6, the shell 5a is like the shell 5 except that
gas evolution, to lessen shattering effects, etc.
its ends are not crimped, and the body of sheath
It should therefore be clearly understood that
ing composition 6 is the same as in Fig. l. The
end closure 7c in Fig. 5 is a simple paper wad of
we may use any suitable non-explosive sheathing
composition, depending on the explosive property
cup-like formation, cemented in the end of the 40 modiñcation desired, without departing from our
shell 5a. When the stick of dynamite is to be in
invention. The sheaths of our invention are also
serted, the wad 'lc may be punched through, or
non-restricted as to diameter, thickness or length,
it may be removed entirely, and after the stick
but will be largely governed by the sizes of ex
of dynamite 9a has been put in place, a new wad,
plosive cartridges, with which they are to be
"id, may be utilized to seal the end of the shell.
45 used, as well as the extent of the explosive prop
It is to be understood that all of the forms
erty modification desired. It is preferable, how
shown may be dipped or otherwise coated with a
ever, in order to produce a sufficiently sturdy and.
protective material such as parañn to improve
effective sheath, that the thickness be at least
their water and/or moisture-resistant charac
about 1/8”--even for small diameter cartridges.
The following non-restricting examples will
While means have been shown for re-sealing
serve to more fully illustrate suitable sheathing
the sheath after the insertion of the stick of ex
compositions of the name-suppressing type, which
plosive therein, there are many situations where
may be used in carrying out our invention:
work is being done under suitable dry conditions
where such re-sealing of the cartridge is not es 55
sential, and it is to be understood that the inven
tion contemplates the use of the sheath consisting
of the shell, and its contained, molded body of
sheathing material, by rupturing one of the end
Per- Per- Per- Per- Per
seals, inserting a stick of explosive therein, and 60
Sodium bicarbonate _____________ __
6l .... __
then using the cartridge within such a limited
Sodium chloride .........
__ ____
time that absorption of atmospheric moisture by
Magnesium carbonatc__
Magnesium sulphate
___________ __
__________ __
__________ _ _
_ ________________ __
the sheathing material becomes a matter of no
Bagasse liber and pit
Asbestos fiber ________________________________ __
3 __________ _,
We may also utilize a sheath of the type illus 65
trated in Fig. '7, wherein at least one of the end
The above exemplary compositions may be suc
closures of Fig. l, indicated 7b, is punctured and
cessfully used to carry out our invention when
folded inwardly, as in Fig, 2, and a cylinder of
thoroughly mixed with 10 to 13% of added wa
thin waxed paper I2 is inserted so as to cover and
protect from moisture the inner surface of the 70 ter, packed by automatic tamping machinery into
Starch ____________ __
sheathing material 6 and retain, in a permanently
open position, the segments of the punctured wad
1b. The explosive cartridge of the ultimate as
sheaths having a thickness of about M1" and out
side diameters up to 2" and subsequently dried.
In certain cases, we have found it desirable,
though not absolutely necessary to our invention.
sembly may then be conveniently inserted into 75 to dissolve or mix certain of the ingredients in
the added water, in order to impart greater dry
strength to the finished sheaths. For example,
it has been indicated to be beneficial to add at
least part of magnesium sulphate and/or starch,
etc., in this manner.
It will be understood, however, that we con
template the use of various means to attain the
degree of sheath strength, necessary to carry
ing out our invention, such as adhesives, fibrous
`when the stick of explosive is thrust into said
bore of the sheath the cut portions of said cap
will fold inward along the inner face of the bore
o’fY the sheath while the. uncut portion thereof
will remain engaged at its outer edge with the
shell and will be drawn tightly over and cover
and protect the end wall of the sheath.
2. The herein described methodj of preparing
an explosive assembly for use, where the assem
binders, solvents, thermosetting materials, plas 10 bly comprises a stick of explosive and a tubular
structure comprising an outer non-metallic shell,
ters, crystallizing compounds, etc.
a rigid tubular sheath of an explosive property
Therefore, it is understood that the invention
modifying medium constituting a lining Within
includes within its purview whatever changes fair
said shell and the bore oi which closely ap
ly come Within either the terms or the spirit of
the appended claims.
We claim:
1. The herein described method of preparing an
explosive assembly for use, where the assembly
comprises a stick of explosive and a tubular struc
ture comprising an outer non-metallic shell, a
rigid tubular sheath of an explosive property
modifying medium constituting a lining within
proximates the external diameter of the stick of
explosive, and a relatively thin paper cap dis
posed across the end of the sheath and secured
at its outer edge to said shell, said method in
cluding the step of radially slitting said end cap
- in a plurality of directions across that portion of
its area which covers the bore of the sheath but
not across the remainder of its area, whereby
when the stick of explosive is thrust into said
said shell and the bore of which closely approxi
bore of the sheath the cut portion of said cap
mates the external diameter of the stick of ex
plosive, and a relatively thin paper cap disposed 25. will fold inward along the inner face or" the bore
of the sheath While the uncut portion thereof
across the end of the sheath and hermetically
will remain engaged at its outer edge with the
sealed at its outer edge to said shell, said method
shell and will be drawn tightly over and cover
including the step of slitting said end cap in a
and protect the end wall of the sheath.
plurality of directions across that portion of its
area which covers the bore of the sheath but
noi-l across the remainder of its area, whereby
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