U.S. patent number 3,628,225 [Application Number 04/746,071] was granted by the patent office on 1971-12-21 for method of making a military blank cartridge.
Invention is credited to Robert W. Parker.
United States Patent |
3,628,225 |
Parker |
December 21, 1971 |
METHOD OF MAKING A MILITARY BLANK CARTRIDGE
Abstract
A blank cartridge for use in military rifles and machine guns,
such cartridge having a metal-coated plastic body the nose of which
is swaged into an elongated tapered configuration after the body is
loaded. An apertured gas-seal and metering element is mounted
between the nose and the base, the latter being locked to the
cartridge body by a locking and sealing insert. In accordance with
the method, the body is a metal-coated plastic extrusion which is
first locked to the base, then loaded with powder, and then swaged
to form the elongated tapered nose portion.
Inventors: |
Parker; Robert W. (Orange,
CA) |
Family
ID: |
24999362 |
Appl.
No.: |
04/746,071 |
Filed: |
July 19, 1968 |
Current U.S.
Class: |
86/19.5; 86/10;
102/530; 264/292 |
Current CPC
Class: |
F42B
8/04 (20130101); B29C 57/10 (20130101) |
Current International
Class: |
B29C
57/10 (20060101); B29C 57/00 (20060101); F42B
8/00 (20060101); F42B 8/04 (20060101); B21d
051/54 () |
Field of
Search: |
;29/1.3 ;86/10,25,39,47
;102/42,43 ;264/292,328 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Campbell; John F.
Assistant Examiner: Craig; Robert T.
Claims
I claim:
1. A method of making a blank cartridge, which comprises:
providing a generally tubular element formed of a thermoplastic
synthetic resin which is capable of diameter reduction by swaging,
swage-reducing one end portion of said tubular element to form an
elongated hollow nose the diameter of which is substantially less
than that of the remainder of said tubular element, and loading
said tubular element with powder.
2. The invention as claimed in claim 1, in which said method
further comprises crimping the end of said nose to provide an
evanescent closure adapted to open in response to firing of the
blank cartridge.
3. The invention as claimed in claim 1, in which said
swage-reducing is effected by applying at a high pressure at least
one die over said one end portion of said tubular element, said die
having a relatively low temperature.
4. The invention as claimed in claim 3, in which said
swage-reducing is effected by applying at high pressures a series
of progressively smaller low-temperature dies over said one end
portion of said tubular element.
5. The invention as claimed in claim 4, in which each of said dies
is applied for only a fraction of a second, and is heated to a
temperature on the general order of about 100.degree. F.
6. The invention as claimed in claim 1, in which said synthetic
resin is a rigid linear polyethylene.
7. The invention as claimed in claim 1, in which said method
further comprises providing a metal coating on said tubular
element.
8. The invention as claimed in claim 7, in which said metal coating
is applied by first oxidizing the surface of said tubular element,
then applying a metallic undercoating to said oxidized surface, and
then electrodepositing said metal coating on said undercoating.
9. The invention as claimed in claim 1, in which said method
further comprises effecting said loading of said tubular element
with powder prior to said swage-reducing step and by introducing
said powder through said one end portion of said tubular
element.
10. The invention as claimed in claim 1, in which said method
further comprises inserting the other end portion of said tubular
element into a generally cup-shaped base prior to said
swage-reducing step and prior to said powder-loading step, and
inserting a locking and gas-seal element into said other end
portion prior to said swage-reducing step and prior to said
powder-loading step, whereby said base is locked and sealed to said
other end portion.
11. The invention as claimed in claim 1, in which said method
further comprises providing a tapered wad formed of a solid and
gas-impervious material, inserting said wad into said tubular
element after said step of loading said tubular element with
powder, and thereafter swage-reducing said tubular element into
contact with said tapered wad whereby to form a tapered shoulder
between said nose and the remainder of said tubular element.
12. The invention as claimed in claim 11, in which said method
further comprises providing said tapered wad with a gas-metering
passage the diameter of which is correlated to the gas-generating
characteristics of said powder.
13. The invention as claimed in claim 1, in which said method
further comprises providing a powder-seal wad in said tubular
element, said powder-seal wad being adapted to disintegrate
harmlessly in response to ignition of the powder charge contained
within said blank cartridge.
14. The invention as claimed in claim 13, in which said method
further comprises providing said powder-seal wad in said one end
portion prior to said swage-reducing step and prior to said
powder-loading step, and effecting lateral compression of said
powder-seal wad in response to said swage-reducing step.
15. The invention as claimed in claim 2, in which said method
further comprises introducing the other end portion of said tubular
element into a generally cup-shaped base, thereafter introducing
into said other end portion a locking wad adapted to lock said
other end portion to said base, thereafter effecting said step of
introducing said powder into said tubular element through said one
end portion thereof, and thereafter effecting at least the final
stages of said swage-reducing and crimping steps.
16. The invention as claimed in claim 1, in which said synthetic
resin is a relatively rigid polyolefin.
17. The invention as claimed in claim 16, in which said polyolefin
is a polyethylene characterized by a high degree of linearity and
crystallinity and having a high molecular weight.
18. The invention as claimed in claim 1, in which said synthetic
resin is selected from a group consisting of linear polyethylenes,
polypropylenes of high isotacticity, styrene butadiene
acrilonitrile terpolymer, ethyl cellulose, and cellulose
acetate.
19. The invention as claimed in claim 1, in which said tubular
element is an extrusion which is open at both ends, in which said
method further comprises closing said other end of said extrusion
prior to said step of loading said extrusion with powder, and
effecting said powder-loading step through said one end portion and
prior to at least the final portions of said step of swage-reducing
said one end portion.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The field is that of military blank cartridges which must be
capable of withstanding extreme heat and cold, and be capable of
generating high gas pressures in order to operate the automatic
weapons, yet should be extremely inexpensive and formed of
nonstrategic materials.
2. Description of the Prior Art
It has long been sought to create a military blank cartridge formed
of plastic, yet which will not jam or otherwise misfunction under
various conditions including relatively extreme heat and cold.
Another major requirement is that the blank cartridge will not
disintegrate and project dangerous portions out of the barrel of
the weapon where they may cause injury to persons or property, or
may start fires. Other major requirements include economy of
manufacture with nonstrategic materials.
Military and other blank cartridges formed of plastic are
conventionally injection molded, but this creates severe problems
in several areas not only relative to cost but also relative to the
fact that nose end portions of the injection-molded cartridges may
blow off and cause injury to persons in the vicinity of the weapon.
Furthermore, it is difficult or expensive to provide an adequate
means for connecting the base to the end of the injection-molded
cartridge body. Such bases are conventionally expensive, being
formed on screw machines or lathes, as distinguished from being
economical stamped elements.
The characteristics of prior art military blank cartridges formed
of plastic are such that they frequently jam or otherwise
malfunction in the automatic weapons in which they are employed. In
this connection, it is pointed out that the temperatures of the
breech portions of the weapons frequently rise to high levels,
which may deteriorate the plastic and thus cause jamming.
Conversely, the weapons are sometimes used in very cold climates,
producing the above and other forms of malfunction. A
representative blank cartridge formed of plastic is shown by U.S.
Pat. No. 2,918,868 for Cartridge.
A considerable amount of art exists in the field of shotgun shells,
representative U.S. Pat. being No. 3,099,958 for Firearm
Cartridges, No. 3,162,124 for Plastic Cartridge, and No. 3,215,075
for Shotshell. These and other shotgun shells are injection molded
and incorporate crimped end portions adapted to retain the shot in
the cartridge. To the best of applicant's knowledge, such shells
are not necked down, by swaging or otherwise, nor are they
metal-coated.
SUMMARY OF THE INVENTION
Applicant has discovered that a metal-coated plastic extrusion,
which is necked down by swaging to provide the tapered and
elongated nose needed for feeding purposes, will not create
substantial jamming problems in the automatic weapon despite severe
temperature conditions. In addition, and very importantly,
applicant provides a relationship such that no portion of the blank
cartridge is projected out the barrel of the weapon where it may
cause injury or start fires. Furthermore, the blank cartridge is
strongly and economically constructed of plastic, aluminum and
other readily available and nonstrategic materials. Novel wad means
are provided (for locking, metering and other purposes) and are
assembled by highly effective and novel methods.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an enlarged longitudinal sectional view of a military
blank cartridge constructed in accordance with the present
invention, prior to firing thereof, a metal coating thereon being
unshown in this and all views excepting FIGS. 3 and 3A;
FIG. 3 is a horizontal sectional view taken on line 3--3 of FIG. 2,
and illustrating a metal coating on the plastic surfaces;
FIG. 3A is a greatly enlarged view illustrating fragmentarily one
portion of the wall, and showing a plurality of metal coatings
thereon;
FIG. 4 is a schematic view illustrating the loading, swaging and
crimping steps performed during manufacture of the blank
cartridge;
FIG. 5 is an enlarged sectional view on line 5--5 of FIG. 4;
FIGS. 6-13 are longitudinal sectional views respectively
corresponding to the eight stations of the apparatus of FIG. 4;
FIG. 14 is an elevational view illustrating one of the stations of
the apparatus of FIG. 4; and
FIG. 15 is a schematic block diagram illustrating the manner of
metal coating the plastic cartridge body.
DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
Referring first to FIG. 1, the military blank cartridge is
illustrated to comprise an elongated plastic case 10 having a
powder-containing body 11 and an elongated tapered nose 12, the
latter terminating in a crimp-folded conical evanescent closure 13.
The region of case 10 between nose 12 and body 11 is shouldered,
relatively sharply tapered, as indicated at 14.
The blank cartridge additionally comprises a gas-metering wad 16, a
powder-sealing wad or bulkhead 17, a locking and gas-sealing wad
18, and a stamped metal base 19 containing a suitable primer 20.
The powder in the blank cartridge is indicated at 21 as being
contained in the chamber 22 which is defined between bulkhead 17
and wad 18, the great bulk of the powder being contained between
gas-metering wad 16 and locking and gas-sealing wad 18.
Stated more specifically, the plastic case 10 is formed by
swage-reducing a tubular extrusion as will be described
hereinafter. The body 11 of the cartridge case is forwardly tapered
slightly (converging toward nose 12), whereas the shoulder 14 is
forwardly convergent (frustoconical) to a much greater degree.
Tapered nose 12 is shown as being forwardly convergent and
frustoconical, the angle of taper being substantially less than
that of shoulder 14 but substantially more than that of body 11.
The conical nose closure 13 is sharply tapered and forms an
evanescent closure adapted to be blown open, but without resulting
in discharge of any case material out of the weapon, as illustrated
at 24 in FIG. 2.
The gas-metering wad 16 is formed of a suitable gas-impervious
material, such as linear polyethylene, having formed therethrough
an axial metering passage 25 which (in the illustrated embodiment)
communicates with a counterbore 26 at the downstream end thereof.
The downstream or front end of metering wad 16 is shown as being
located adjacent the junction between nose 12 and shoulder 14, but
it is pointed out that in some forms of the invention the metering
wad may initially be mounted much closer to base 19 and then
gas-shifted upon firing of the cartridge to the position
illustrated in FIGS. 1 and 2.
The peripheral wall of metering wad 16 has a front portion which
tapers correspondingly to the taper of shoulder 14 so that such
elements will be in surface engagement as illustrated.
Correspondingly, the rear portion of wad 16 tapers only slightly,
corresponding to the portion of body 11 which is relatively
adjacent shoulder 14. The rear surface 27 of wad 16 is shown as
being frustoconical and forwardly convergent, this permitting
radial-outward flexing of the rear wad portion into gas-sealing
engagement with body 11 upon firing of the cartridge.
The powder-enclosing or sealing wad or bulkhead 17 is seated on the
forward surface of metering wad 16, being formed of a material
which will not create any damage or injury, or start fires, in
response to projection of components thereof out of the weapon in
which the cartridge is fired. More specifically, wad 17 is
preferably formed of expanded beads of polystyrene as specified in
U.S. Pat. No. 3,354,571 for Blank-Cartridge Gun and Cartridge
Therefor. The wad 17 prevents passage of any powder 21 out through
the passage 25 and counterbore 26, so that the powder remains in a
relatively compact mass and so that the nose 12 remains empty. It
is emphasized that there is nothing between wad 17 and the
evanescent nose closure 13. Accordingly, the only things which pass
out of the gun are the products of combustion of powder 21, and the
minute disintegrated particles of the wad 17.
Locking and gas-sealing wad 18 may be formed of a suitable plastic,
such as linear polyethylene, being force-fit into body 11 adjacent
base 19. The fit is caused to be sufficiently tight to insure that
there is locking engagement between base 19 and the rear end of
cartridge body 11, and also sufficiently tight to prevent escape of
any gas through the interface between the base and the cartridge
body. The locking and gas-sealing wad 18 may perform this locking
and sealing function, even with a base 19 which is stamped and thus
extremely inexpensive to manufacture, because of the fact that the
wad may be introduced into the cartridge body 11 prior to
swage-reduction of the cartridge case.
Formed through wad 18 is an axial passage or port which registers
with a central port in the center of base 19 and permits passage of
explosive gases from primer 20 into the powder chamber 22. The
powder 21 will thus be ignited upon striking of the primer.
The base 19 may be a cup-shaped stamping made of a suitable
nonstrategic metal, such as aluminum, having a cylindrical sidewall
which is necked inwardly to provide an annular groove 31 adjacent
the extractor rim 32. The bottom or rear wall of the base 19 is
recessed and apertured to receive primer 20 in press-fit (and
preferably staked) relationship.
The type and quantity of powder 21 are selected to generate the gas
pressure necessary to properly operate the automatic weapon, and to
create the desired sound effects, etc. The diameter of the passage
25 in wad 16 is correlated to the type and quantity of powder in
such manner that the pressure buildup in powder chamber 22, in
response to ignition of the powder, will be that desired for the
particular weapon. Thus, it is possible to change powders by merely
changing the diameter of the bore or passage 25, and without
changing any other characteristic of the cartridge. However, if
lesser quantities of powder are required it may be desired to shift
the metering wad 16 toward the base and thus reduce the size of the
powder chamber.
Because the cartridge case 10 is swage-reduced from a tubular
extrusion, without the necessity of injection molding, it is not
only extremely economical to manufacture but also (as indicated
above) eliminates prior art problems relative to blowing out of the
nose portion of the blank cartridge. In injection-molded cartridge
cases, wherein the nose is molded in closed condition but with
score lines adapted to permit rupture, it frequently occurs that
the score regions are either too thin or too thick. If they are too
thin, breakage frequently occurs and permits portions of the
cartridge case to blow out and cause injury. On the other hand, if
the score regions are too thick there may be excessive pressure
developed within the cartridge, resulting in adverse effects
including blowback of the base. With the present construction
wherein the nose is folded or crimped shut, there are no score
regions and there is no danger that portions of the cartridge body
will blow out or will refrain from blowing out and thus create
adverse pressure conditions.
Cartridge body 11 may be provided with longitudinal ribs and
grooves (not shown) in order to facilitate extraction after firing.
It is emphasized, however, that extraction is facilitated because
of the fact that the plastic from which the body is formed is a
type which contracts or shrinks when heated, so that shrinkage
occurs after firing. The plastic expands during the period when the
cartridge is being fired, due to the presence of gas pressure in
chamber 22, but immediately contracts after firing so that
extraction is rendered easy. There is, therefore, less danger of
jamming, less wear on the chamber wall, and less wear on the
extractor mechanism, than in the case of cartridges formed of
brass, for example.
In accordance with an important feature of the present invention,
extraction is rendered even more certain, and operation under
extreme conditions of heat and cold rendered more reliable, by
coating the cartridge case 10 with metal. Because of the presence
of the metal coating, very little friction is created between the
cartridge case and the chamber wall even when the latter is very
hot, so that extraction is still possible and no jamming
occurs.
Because the metal coating on the cartridge case is thin, it is
shown only in FIGS. 3 and 3A, and one method of applying the same
is illustrated schematically by block diagram FIG. 15. It is to be
understood, however, that the coating may be regarded as present on
all of the remaining views.
Referring to FIG. 3, a metal coating 35 is shown as provided on the
cartridge body 11, but such coating is also present on the
remaining exterior and interior portions of the cartridge case 10.
The coating may be a suitable metal, for example nickel, which may
be electroplated or otherwise applied onto the cartridge body after
preparation thereof as will be described subsequently.
Referring to FIG. 3A, there is shown as present under the exterior
coating 35 an interior or preparatory coating 36 adapted to permit
electroplating of the exterior coating 35 onto the plastic. One
manner of applying the coatings 35 and 36 will be stated
hereinafter relative to FIG. 15.
The plastic employed to make the cartridge case 10 is a
thermoplastic synthetic resin, which is capable of being swaged to
reduce diameters in response to application of low heat and high
pressure, and is relatively impervious to the adverse effects of
ambient heat and cold. The resin should be rigid, should be capable
of receiving a metal coating as described hereinafter or by other
processes, and should shrink in response to application of
heat.
A preferred resin is a relatively rigid polyolefin, preferably a
polyethylene characterized by a high degree of linearity and
crystallinity and by a high molecular weight. Such polyethylenes
are produced by various processes under relatively low temperatures
and low pressures of polymerization using suitable catalysts in
admixture. They have high densities and molecular weights, and a
high degree of linearity in the polymer chains. They have high
softening or melting points and may be classified as rigid
polyethylenes.
Stated otherwise, the resin may be a type III polyethylene as
described by ASTM (American Society of Testing Materials)
specification O-1248. More specifically, the rigid polyethylene
employed is "Plaskon 6-34," a trademark of Allied Chemical
Corporation, and which is a high-density polyethylene produced by
the catalytic polymerization of ethylene. Butene-1 is present
during the polymerization in small amounts. The resulting polymer
will have a nominal density of 0.946 gram/cc. using ASTM D 1505.
Resin molecular weight is high. When tested by ASTM D 1238,
condition F, the melt flow has a nominal value of 3.5 grams/10
minutes. "Plaskon 6-34" is stabilized with 0.1 percent Santowhite
Powder and 0.1 percent dilouryl thiadipropionate.
Resins other than linear polyethylene, and which may be employed in
some instances to make the present cartridge case, include styrene
butadiene acrylonitrile terpolymer, polypropylene of high
isotacticity, ethyl cellulose, and cellulose acetate.
METHOD OF MANUFACTURE
Referring first to FIG. 4, a table or support 40 has mounted
thereon a stationary backup bar 41 adjacent which is a movable or
walking feed element 42. As shown in FIG. 5, the walking element 42
has portions 43 shaped to receive the extractor rim 32, and other
portions shaped to fit into annular groove 31 of each cartridge
base 19. Thus, the cartridge base is locked in position except when
intentionally moved by the element 42.
The relationship is such that the element 42 oscillates back and
forth once for each operation of the swaging and assembly
apparatus, in such manner that the cartridge bases 19 and connected
components move forward from each station to a predetermined
adjacent station.
Shown at the extreme left of FIG. 4 is a chute 45 through which
passes a prestamped cartridge base 19 having preassembled therewith
a primer 20. Upon the next movement of feed element 42, the base 19
from chute 45 passes to the first station, being disposed at a
predetermined point beneath a tube-assembling mechanism a portion
46 of which is shown in section in FIG. 6. Portion 46 has formed
therein a cylindrical passage 47 the lower end of which is
counterbored at 48 to receive the cylindrical wall of base 19.
Suitable mechanism, not shown, is provided to move the portion 46
downwardly until the base is partially received in counterbore 48,
following which a tube-feeding mechanism is employed to feed a
cylindrical plastic tube 49 (namely, an extrusion which has been
suitably cut to length) downwardly through passage 47 and into the
base.
The cylindrical wall of base 19 is backed up by portion 46, and is
therefore not expanded by the tube 49 despite the fact that the
latter is preferably pressed into the base in a press-fit
relationship. Thereafter, the portion 46 is elevated to a position
above extrusion 49 and the mechanism 42 is operated to shift the
base 19 and associated tube 49 to the next station as illustrated
in FIG. 7.
At such next station, a backup portion 51 is inserted downwardly
over tube 49 and over the cylindrical body of base 19. Connected to
such portion 51 is an internal insertion element 52 which is shaped
to force the locking and gas-sealing wad 18 downwardly into the
base to thereby firmly lock the tube 49 to the base, this being a
tight press-fit relationship which (again) does not expand the base
due to the fact that the latter is backed up by element 51. A vent
passage 53 is provided through insertion element 52 to permit
escape of air as the element is inserted into the tube. Thereafter,
elements 51 and 52 are lifted upwardly to positions above tube 49,
and the base and tube are shifted to the next station as shown in
FIG. 8.
Powder 21 is loaded into the tube 49 at such next station, FIG. 8,
through a passage 54 in a loading portion 55 which is shifted
downwardly over the tube 49 and the base. The quantity of powder is
metered to provide the requisite gas pressure, etc.
At the next station, FIG. 9, the gas-metering wad 16 is first
dropped down tube 49 so that it will be supported upon the powder
21 therein, following which an initial swaging and positioning
means 56 is moved downwardly over the extrusion 49 and over the wad
16. The wads 16, 18, etc., are fed into the tube by suitable
mechanism, not shown.
The swaging and positioning means 56 includes an outer or swaging
portion having a tapered or frustoconical interior wall 57 adapted
to cause tapering of substantially the full length of the tube 49.
Such tapering is effected because of the pressure of the downwardly
moving element 56, and also because such element 56 incorporates
means to heat the wall 57 to a desired low temperature. In the
illustrated embodiment, the heating means comprises an annular
water chamber 58 through which water at a predetermined temperature
is continuously fed via passages which are schematically
represented at 59 and 60. Other heating means, for example
electrical, may be employed in place of heated water.
It has been found that the temperature to which the wall 57 should
be heated, the pressure of the downwardly moving element, the rate
of swaging, and other factors, may vary somewhat in accordance with
the wall thickness of the tube, the precise type of plastic of
which the tube is formed, etc. Stated generally, the temperature of
the swaging wall should be sufficiently high to make the plastic
swageable at high pressures, but not sufficiently high to cause the
plastic to shrink. The temperature also varies in accordance with
the duration of the cycle, the temperature of the wall 57 being
higher when the cycle is relatively short.
For the "Plaskon 6-.div." rigid polyethylene plastic, for example,
the wall temperature may be surprisingly low and the cycle
surprisingly short. Thus, for example, the element 56 may only be
in contact with the tube for a fraction of a second, and the wall
57 need only to be heated to a temperature on the general order of
about 100.degree. F. The swaging pressure is high, being sufficient
to create the indicated swage reduction.
The desired swaging occurs at such low temperatures that it is in
the nature of cold working. The plastic is thus caused to have
particularly desirable properties.
The positioning portion of element 56 comprises an interior element
59a which engages the upper end of metering wad 16 and causes the
wad to be disposed at the proper elevation in the plastic tube. The
element 59a, the tapered tube, and the powder 21 cooperate to
maintain the metering wad 16 in the desired location. Element 59a
has a suitable vent passage therethrough.
Referring next to FIG. 10, there is provided at the next station a
swaging and positioning element 61 having a lower portion 62 which
fits over the cartridge body and the base 19 for backup and
positioning purposes. The upper portion of element 61 is suitably
heated, for example by means of a water chamber 63 and associated
passages 64 and 65. The portion of element 61 radially inwardly of
water chamber 63 has a wall 66 shaped to initially neck-down the
plastic in the vicinity of the tapered front portion of metering
wad 16. In advance (upwardly) of the forward portion of metering
wad 16, the wall 66 is adapted to commence effecting the elongated
taper which forms the nose 12 of the cartridge body.
The powder-seal wad 17 (which is resilient in nature) is introduced
into the cartridge body prior to downward movement of element 61,
by suitable mechanism, not shown. It is positioned on the front or
upper surface of wad 16 by an insertion element 67 having a vent
passage 68 therethrough.
At the next station, FIG. 11, a swaging element 71 having a lower
positioning portion 72 is moved downwardly over the plastic tube. A
water chamber 73, through which water is fed via passages 74-75, is
provided in element 71 in order to heat the plastic around element
16 and also around the nose. The interior wall of the element 71
inwardly of chamber 73 is shaped to neck-down the plastic at wad 16
and also to continue the tapering of the nose portion of the
cartridge case. A suitable vent 76 is provided.
It is emphasized that the swage-reduction of the cartridge case
adjacent and in advance of metering wad 16 not only continues the
operation of forming the shoulder 14 and nose 12, but also effects
a compression of powder-seal wad 17. A highly effective powder seal
is thus achieved.
Referring to the next station, shown in FIG. 12, a swaging element
78 having a lower positioning and backup portion 79 is moved
downwardly over the cartridge in order to effect further
necking-down and tapering of the nose portion of the cartridge. As
at previous stations, a water chamber 80 fed through passages 81-82
is provided, as is vent 83. The upper region of the element 78 is
suitably shaped to commence star-crimping of the cartridge end, as
indicated at 84.
At the next station, FIG. 13, a closure element 86 having a lower
positioning and backup portion 87 is adapted to complete the
evanescent crimp-closure 13. For this purpose, a water chamber 88
and associated passages 89-90 and vent 91 are provided.
After passing through all the stations, the shell is automatically
fed out through a chute 92 (FIG. 4) into a packing mechanism.
Although a completed cartridge is shown in the chute 92 at FIG. 4,
it is to be understood that the cartridge would normally have
passed down the chute 92 when the elements are in the illustrated
positions. This is because FIG. 4 shows all of the parts after the
associated forming elements have operated thereon, but prior to
shifting to the next adjacent station.
Referring next to FIG. 14, there is shown schematically as
associated with one of the elements, namely, number 86-87, a
double-acting hydraulic cylinder apparatus 93 adapted to force the
element 86 downwardly over the cartridge at a desired fluid
pressure. A thermostatically controlled source 94 of water is shown
as connected through hoses 95-96 with passages 89-90, respectively.
Although FIG. 14 shows only one of the stations, it is to be
understood that similar hydraulic cylinders, and associated
heating, charging or other apparatus, are provided at the other
various stations as indicated above.
All of the elements 46, 51, 55, 56, 61, 71, 78 and 86 (FIG. 4) move
up and down in substantial unison, but the pressure of each is
individually controlled as is the temperature of the water passed
therethrough (in those instances where water chambers are
provided). Such conjoint movement is achieved by suitable valve
means associated with cylinders such as the cylinder 93 of FIG. 14.
The conjoint movement of the cylinders is correlated to the
movement of the walking feed element 42, the latter operating when
the swaging elements, etc., are in their uppermost positions and
being stationary when the swaging elements are moved downwardly or
upwardly.
Referring next to FIG. 15, it is an important feature of the
present invention that the cartridge body is metal-coated as
described hereinabove relative to FIGS. 3 and 3A. Metal-coating may
be effected prior to the forming steps illustrated in FIG. 4, or
may be effected after the cartridge has been otherwise completely
manufactured. In the latter case, suitable means (such as paraffin)
are provided to insure against ingress of fluid through the closure
13 or through the primer 20.
The coating may be effected relative to the elongated plastic
extrusion from which the lengths of tubing 49 are cut. For example,
the elongated extrusion is first fed through an oxidizing means 100
adapted to effect oxidation of the exterior surface of the tube.
Such oxidizing means may comprise a flame device, adapted to
momentarily direct flame against the exterior surface of the tube,
or it may comprise a suitable chemical. The oxidizing step
conditions the plastic for reception of the inner or preparatory
coating 36 (FIG. 3A). Such coating is very thin and is applied by
means of the preplating bath 101 indicated schematically in FIG.
16. As an example, the preplating bath may comprise a lecherous
nickel bath adapted to apply a coating only about 55 millionths of
an inch thick, such coating being somewhat impregnated into the
oxidized exterior surface of the tubing.
The precoating 36 prepares the tube for electroplating, which is
effected in electroplating bath 102. For example, bath 102 may
comprise an electrolytic nickel-plating bath adapted to apply the
nickel coating (the exterior coating) which is represented at 35 in
FIGS. 3 and 3A. As indicated hereinabove, coating 35 insures
against jamming of the cartridge in the chamber despite extreme
temperature conditions.
The plastic extrusion may also be coated after it is severed into
the tubes 49, both the exterior and interior plastic surfaces then
being metal-coated as shown in FIGS. 3 and 3A.
The foregoing detailed description is to be clearly understood as
given by way of illustration and example only, the spirit and scope
of this invention being limited solely by the appended claims.
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