U.S. patent number 3,757,693 [Application Number 05/280,589] was granted by the patent office on 1973-09-11 for fragmentation wrap for explosive weapons.
This patent grant is currently assigned to Avco Corporation. Invention is credited to Frank M. Shea.
United States Patent |
3,757,693 |
Shea |
September 11, 1973 |
FRAGMENTATION WRAP FOR EXPLOSIVE WEAPONS
Abstract
A fragmentation wrap for explosive weapons is disclosed. The
fragmentation sheet for explosive weapons having a predefined
fragmentation shape therein is fabricated by the progressive
flattening, shearing and/or indenting of hot or cold rolled steel.
The complete fragmentation wrap may be a single layer or
multi-layer wrap which is conformed to enclose a bomb or the
like.
Inventors: |
Shea; Frank M. (Cincinnati,
OH) |
Assignee: |
Avco Corporation (Richmond,
IN)
|
Family
ID: |
26843215 |
Appl.
No.: |
05/280,589 |
Filed: |
August 14, 1972 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
145695 |
May 21, 1971 |
|
|
|
|
Current U.S.
Class: |
102/493;
102/482 |
Current CPC
Class: |
B21D
31/02 (20130101); F42B 12/22 (20130101); B21D
28/10 (20130101) |
Current International
Class: |
B21D
28/10 (20060101); B21D 31/00 (20060101); B21D
31/02 (20060101); F42B 12/22 (20060101); F42B
12/02 (20060101); F42b 013/48 () |
Field of
Search: |
;102/64,67 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Borchelt; Benjamin A.
Assistant Examiner: Tudor; H. J.
Parent Case Text
This application is a division of Ser. No. 145,695, filed May 21,
1971.
Claims
What is claimed is:
1. A fragmentation wrap for wrapping around the exterior of
explosive devices such as bombs, missiles and the like comprising a
continuous planar sheet of metal having individually shaped
fragment elements formed therein, a plurality of substantially
linear shear lines repetitively formed in said sheet in slanted
relation to the sides of said sheet, said shear lines being
linearly displaced along the length of said sheet an incremental
distance according to the fragment design, said substantially
linear shear lines defining a partial perimeter of a geometric
shape wherein adjacent repetitive shear lines combine to define the
individual fragment elements of a given geometric shape, said
fragment elements being connected together by unsheared portions of
the perimeter.
2. The fragmentation wrap according to claim 1 in which the shear
lines are partially discontinuous wherein additional non-sheared
links connect the individual fragment elements linearly along the
length of the fragmentation wrap.
3. The fragmentation wrap according to claim 2 in which said
fragmentation wrap is conformed about the exterior surface of an
explosive device, and further comprising a thin skin covering the
outside surface of said fragmentation wrap to provide a smooth
external aerodynamic surface, said skin serving as a structural
part and as a fairing for said explosive device; and a pair of
bands secured around said skin and fragmentation wrap at a front
and rear thereof to hold said wrap and skin against the explosive
device.
4. A fragmentation wrap according to claim 1 further comprising a
second planar sheet having sheared fragment elements formed
therein; and means interposed between said sheets to prevent
welding of fragment elements together due to the energy generated
during explosion of the explosive device.
Description
The invention herein described was made in the course of or under a
contract with the Department of Defense.
BACKGROUND OF THE INVENTION
The present invention relates generally to explosive weapons of the
fragmentation type and more particularly to new controlled
fragmentation wraps for projectiles and missiles in which the
fragmentation wrap may be mass produced having predefined
fragmentation shapes.
Various methods have been used heretofore to produce fragments of
varying size and shape when a fragmentation-type weapon is
exploded. None of the previous methods are entirely satisfactory
for producing fragmentation wraps of a sufficient size to encompass
large bombs, missiles and the like. One well-known method of
fabricating controlled fragmentation warheads is by the process of
casting the warheads in a casting form having a groove pattern. Due
to the time intervals involved in the casting operation and the
required size of wraps needed for the large bombs, this method is
impractical for mass production purposes since it requires numerous
casting forms in order to compensate for the time losses in each
casting form and a prohibitively large manufacturing plant to
install the numerous casting forms required. Moreover, experience
has shown that cast-produced warheads are unsatisfactory due to
erratic fragmentation and due to pulverization into useless chaff a
substantial portion of the warhead.
Another less than satisfactory procedure which has been suggested
is the use of presized fragments held in place by thin sheets of
metal and adapted to be disbursed upon the detonation of the
explosive charge associated therewith.
A still further less-than-satisfactory method consists of sawing
notches or grooves in stock bars, forming the bars into rings and
welding the ends thereof together. Surface grinding the two faces
of the rings to make them flat and parallel, supercoincidentally
stacking the rings in a suitable jig, and copper brazing, in a
hydrogen furnace, the side faces of adjacent rings to form a hollow
tube for encasing an explosive charge. These methods are inherently
complex, time-consuming, and impractical for mass production of
fragmentation wraps of large dimensions.
A further object of this invention is to provide a fragmentation
wrap having predetermined fragment shapes, the fragmentation wrap
being of such a dimension that it may be utilized in conjunction
with large explosive weapons.
SUMMARY OF THE INVENTION
This invention provides for new and improved fragmentation wraps
for explosive weapons. The fragmentation wrap of this invention is
fabricated by the feeding of a hot or cold rolled steel sheet
progressively through shearing dies. The die makes repeated
shearing cuts and/or indentations in the sheet at a predetermined
angle from the normal of the sheet direction. This action
simultaneously flattens the sheet. Each shearing cut is displaced
by a predetermined linear feed. The repeated shearing cuts and/or
indentations combine to define and provide the desired
fragmentation shape. The fragmentation sheet so fabricated may be
used in a single layer wrap for the explosive weapon or a plurality
of sheets in sandwich form may be utilized.
Other details, uses, and advantages of this invention will become
apparent as the following description of the exemplary embodiment
hereof presented in the accompanying drawings proceeds.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings show present exemplary embodiments of
this invention in which:
FIG. 1 is a diagrammatic perspective view illustrating the manner
of fabricating a progressive shear pattern in a sheet in accordance
with the preferred concept of this invention;
FIG. 2 is a plan view of a portion of a fragmentation wrap sheet
made in accordance with the present invention;
FIG. 3 is an elevation view taken along lines 3--3 of FIG. 2;
FIG. 4 is a cross-sectional view taken on the line 4--4 of FIG.
2;
FIG. 5 is a diagrammatic representation of a desired fragment shape
generally shown in FIG. 2;
FIG. 6 is a diagrammatic plan view of the die illustrated in FIG.
1;
FIG. 7 is a diagrammatic partial view of the fragmentation pattern
of FIG. 2;
FIG. 8 is a diagrammatic representation illustrating another
exemplary fragment shape;
FIG. 9 is a diagrammatic plan view illustrating another exemplary
die to form the fragment shape of FIG. 8;
FIG. 10 is a diagrammatic partial view of the fragment pattern
formed by the die of FIG. 9;
FIG. 11 is a diagrammatic representation illustrating a further
exemplary fragment shape;
FIG. 12 is a diagrammatic plan view of a die used to form the
fragment shape of FIG. 11;
FIG. 13 is a diagrammatic partial view of the fragment pattern
formed by the die of FIG. 12;
FIG. 14 is a diagrammatic representation illustrating a still
further exemplary fragment shape;
FIG. 15 is a diagrammatic plan view of a die used to produce the
fragment shape of FIG. 14;
FIG. 16 is a diagrammatic partial view of a fragment pattern formed
by the die of FIG. 15;
FIG. 17 is a diagrammatic representation illustrating another
exemplary fragment shape;
FIG. 18 is a diagrammatic plan view of a die used to produce the
fragment shape of FIG. 17;
FIG. 19 is a diagrammatic partial view of a fragment pattern formed
by the die of FIG. 18;
FIG. 20 is an elevation view of a typical bomb incorporating the
fragmentation wrap of this invention; and
FIG. 21 is a partial elevation view of a multi-layer fragmentation
wrap.
DESCRIPTION OF ILLUSTRATED EMBODIMENTS
Referring now to FIG. 1 in describing the method of the invention,
a planar sheet of hot or cold rolled steel 100, or of any metallic
material or alloy suitable for such purposes, is passed axially in
the direction of arrow 110 between opposing dies 102 and 104. The
dies are constructed to have a cooperating shear edge 106. In the
first embodiment of this invention, the dies also have indented die
elements 108 displaced from the shearing edge 106. The dies 102 and
104 may both be movable in a vertical direction. In the illustrated
embodiment shown, die 104 is stationary. The die 102 is then
vertically driven towards the stationary die 104 by a suitable
press (not shown). The dies 102 and 104 will cooperatively engage
the sheet 100 to perform the desired flattening, shearing and/or
indenting functions described hereinbelow. Means are provided to
move the sheet 100 through the die at a predetermined linear feed
or rate.
The means for feeding the sheet and press, which are not shown, may
be driven by any suitable motive power means and may be
interconnectingly geared and synchronized so that the sheet is fed
a predetermined incremental distance during each press stroke. At
the end of each stroke, the dies perform the flattening, shearing
and/or indenting whereupon the sheet is again moved the prescribed
distance for the subsequent action of the dies. Each action of the
dies provides a partial fragment pattern on the sheet. Each pattern
is placed at an angle to the axial feed of the sheet. As the sheet
is incrementally fed through the dies at the predetermined feed per
stroke, additional partial patterns are formed sequentially on the
sheet. The sequential partial patterns combine to provide the
desired fragment effect.
One desired fragment shape is generally shown in FIG. 5. The
pattern shape is fully defined by its symmetry and the dimensions
P, G and r. From these dimensions, the following relationships
exist:
arc tan .alpha. = (G - P)/r
arc tan .beta. = (P + G)/r
2a = .sqroot.r.sup.2 + (P + G).sup.2
FIG. 7 illustrates how the individual fragments of FIG. 5 may be
arranged within the sheet 100 to gain 100 percent material
utilization. The arrow 110 indicates the direction of feed of the
sheet 100 relative to the dies. It may be observed that the lines
AB, BC, and CB.sub.1 are repeated as A.sub.1 B.sub.1, B.sub.1
C.sub.1 and C.sub.1 B.sub.2 by the linear displacement a. A
subsequent displacement by the distance a will generate lines
A.sub.2 B.sub.2, B.sub.2 C.sub.2, and C.sub.2 B.sub.3. Referring
now to FIG. 6, an examplary die utilized to provide the
fragmentation pattern of FIG. 7 is shown in diagrammatic plan view.
The die is provided with a continuous shearing edge 106. As the
sheet 100 is passed between the dies at a feed stroke a, the dies
will progressively shear the sheet 100 along the lines AB, BC, then
A.sub.1 B.sub.1, B.sub.1 C.sub.1, then A.sub.2 B.sub.2, B.sub.2
C.sub.2, etc., for each linear displacement of the sheet 100. It is
thus seen that the shearing edge 106 will progressively shear the
fragmenting pattern into the sheet 100 except that the short sides
CB.sub.1, C.sub.1 B.sub.2, etc., will not be provided.
The lines CB.sub.1, C.sub.1 B.sub.2, etc., may be provided by
utilizing a progressive die setup wherein a plurality of indenting
dies or punches 108 are linearly displaced from the shearing edge
106 by a distance of at least the stroke or a multiple thereof.
Since the sheet 100 will expand along the shearing edge due to the
heat generated therein due to the shearing operation, it is
necessary that the indenting step take place separate from the
shearing step in order to compensate for the die expansion due to
heat rise. It should be noted that the indenting punches 108 may be
displaced either behind or ahead of the shearing edge 106. In order
to have the fragmentation sheet 100 held together without the
necessity of joining each fragment to another, the sides CB.sub.1,
C.sub.1 B.sub.2, etc., are indented rather than sheared. In this
way, the individual fragments are held together by the indented
area. An unsheared zone is left at each edge of the sheet 100 in
order to insure coherency of the sheets. Furthermore, the shearing
edge 106 may be interrupted as at 112 to provide a solid unsheared
bar the linear length of the sheet 100 to provide an additional
zone for maintaining the individual fragment in place. FIG. 2 shows
a plan view of a fragmentation sheet 100 formed with the die
described in FIG. 6. The individual fragment shapes or elements 114
are held together by the indented area 116 (FIGS. 3 and 4). A
typical zone where shearing is omitted is indicated generally at
118 in FIG. 2. The zone 118 results when the shearing edge 106
(FIG. 6) has an interrupted shearing edge 112.
Another exemplary embodiment of this invention is shown in FIGS. 8
and 10. The fragment element 120 is seen to be a diamond shape. In
this embodiment, the indenting step is not needed. The individual
fragment elements 120 are held together by a tie connection 122.
The fragment sheet of FIG. 10 may be fabricated by using a shearing
die 124 (FIG. 9) which has the desired shearing edge 126. The die
124 is seen to comprise a similar shearing edge 128. The use of
shearing edges 126 and 128 premits the full width of the fragment
sheet to be sheared simultaneously. It is seen that the shearing
edges 126 and 128 are separated by a non-shearing area 130. Thus, a
zone of non-sheared sheet will effectively join both sides of the
finished fragmentation sheet. Additional strength and support for
the fragmentation sheet may be provided through the use of
additional interruptions 132 and 134 in the shearing edges so as to
provide additional linear zones of non-shearing. It should be
noted, however, that the die 124 may comprise only a single
shearing edge similar to FIG. 6 and still provide the desired
fragmentation sheet structure. In FIG. 10, the edge 136 represents
a sheared pattern formed by the shearing edge 126 of die 124. The
next sheared edge 138 is linearly separated from edge 136 by a
distance equal to stroke a'.
Referring now to FIGS. 11 and 13, the fragment element 140 is seen
to be square shaped. The fragment elements 140 are joined by the
non-sheared connecting tie 142. The die 144 comprises shearing
edges 146 and 148 interrupted by a non-shear area 150. In FIG. 13,
the sheared edges 152 and 154, formed by shearing edge 146, are
separated by a linear distance of stroke a". Due to the method of
progressively advancing the fragment sheet through the dies, it may
be noted that the resulting sheared edges are commonly in a
straight line along the outlines of the fragments. This provides
for a greater uniformity of dispersal of the fragments.
By utilizing a die 156 in the shape shown in FIG. 15, the fragment
shape 158 (FIGS. 14 and 16) is shown. The die 156 has dual shearing
edges for the left half and right half of the fragmentation sheet.
Each shearing edge has a plurality of interrupted non-shearing
portions 160 to provide tie areas 162 between each fragment element
158, in this instance, it is seen that each individual fragment 158
has a tie 162 along each of its geometric edges. The fragment
elements 158 are formed by the progressive cross-shearing of prior
sheared edges.
The die 164 of FIG. 18 is similar to that described for the diamond
shaped die in FIG. 15. The die 164 provides a fragmentation sheet
having individual fragment elements 166 (FIGS. 17 and 19) tied
together by tie areas 168.
Although the dies hereinabove described have been illustrated as
planar, it may be noted that roll-type dies may also be utilized to
provide the necessary shearing and/or indenting to make the
necessary fragment elements. In the fragmentation wrap design
formed by the method of this invention (FIGS. 16 and 19) each
fragment is attached to its neighbor by an unsheared bridge or tie.
These bridges can be alternated from top to bottom for each
specific shearing edge by the placement of the interrupting
non-shearing portions of the shear edge. This produces the sheet
uniformly tied together which may eliminate the continuous linear
tie bar from end to end of the sheet except at the center where the
notching dies or rolls face each other.
In general, the function of the dies are the same and variations in
the fragmentation design is incorporated into the die proper. In
all cases, the material passes through the dies in repetitive steps
or increments of a given feed stroke (in the case of planar dies)
or at a proper spacing between shearing edges (for roll dies.)
In the case of "roll dies," the shearing pattern is interrupted as
required to provide necessary tie bars between individual fragment
elements.
FIG. 20 generally shows a bomb 170 about which a fragment wrap 172
has been placed. The fragmentation wrap 172 is contoured to match
the exterior shape of the bomb. An outer aluminum skin or the like
174 (partially cut away) serves in a dual capacity as a structural
member and fairing to provide a smooth aerodynamic surface.
Suitable means such as steel bands or the like 176 secure the skin
and fragmentation wrap to the bomb together with a retention device
(not shown).
The fragmentation wrap 172 may be a single layer (FIG. 3) or a
multi-layer, as the designs dictate. FIG. 21 shows an elevation
view of a typical multi-layer fragmentation wrap. To avoid welding
of the individual fragments to one another due to the energy
generated by the explosion, a layer of kraft paper or the like 178
is cemented inside each of the fragmentation layers 180 and 182.
This paper may also be used to identify the side of the sheet for
correct forming.
It can be seen from the foregoing description, that this invention
provides a novel method for producing fragmentation wraps through
the progressive shearing of partial fragment patterns repetitively
on a sheet of material. The partial patterns are formed so as to
combine to provide the desired fragment shapes. Indenting dies may
be used together with the shearing dies for some designs.
Accordingly, the objectives of this invention hereinabove set forth
have been accomplished.
While present exemplary embodiments of this invention have been
illustrated and described, it will be recognized that the method of
this invention and fragmentation wrap thereby formed may be
otherwise variously embodied and practiced by those skilled in the
art.
* * * * *