U.S. patent application number 12/791212 was filed with the patent office on 2011-09-15 for architecturally design mortar base plate.
This patent application is currently assigned to CVDTEK, LLC.. Invention is credited to John D. Gugliotta, Glenn Leppo, Haluk Sayir, Christopher H. Willison.
Application Number | 20110219945 12/791212 |
Document ID | / |
Family ID | 44558695 |
Filed Date | 2011-09-15 |
United States Patent
Application |
20110219945 |
Kind Code |
A1 |
Sayir; Haluk ; et
al. |
September 15, 2011 |
Architecturally Design Mortar Base Plate
Abstract
An architecturally design mortar base plate is provided having
an architecturally design structure having a center receiving hub
and socket made of one piece machine from solid steel for socket to
absorb the impact over repeated cycling. A plurality of forged
metal ribs extend radially out therefrom to distribute the impact
strength from the socket regime to throughout the whole base volume
to consume the energy that created due to firing.
Inventors: |
Sayir; Haluk; (Norton,
OH) ; Willison; Christopher H.; (Norton, OH) ;
Gugliotta; John D.; (Richfield, OH) ; Leppo;
Glenn; (Norton, OH) |
Assignee: |
CVDTEK, LLC.
|
Family ID: |
44558695 |
Appl. No.: |
12/791212 |
Filed: |
June 1, 2010 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61182455 |
May 29, 2009 |
|
|
|
61239219 |
Sep 2, 2009 |
|
|
|
Current U.S.
Class: |
89/37.05 |
Current CPC
Class: |
F41A 23/54 20130101 |
Class at
Publication: |
89/37.05 |
International
Class: |
F41A 23/54 20060101
F41A023/54 |
Claims
1. An architecturally design mortar base plate for use in
combination with an otherwise conventional mortar, said mortar base
plate comprising: a center receiving hub forming a socket; a
plurality of ribs attached to and extend radially out from said
hub; a stabilizer pad formed to receive an assembly of said hub and
said ribs, said stabilizer pad for operatively distributing recoil
and impact strength exerted at said socket to throughout the whole
base volume to consume the energy that created due to firing.
2. The mortar base plate of claim 1, wherein said stabilizer pad is
formed of a material selected from the group comprising: synthetic
rubbers; thermoplastic rubbers; urethanes; Kevlar.RTM.; polymer
mixed with carbon fiber shreds; mesh or polymer resin; metal;
ceramic polymer matrix; and other structural fabric.
3. The mortar base plate of claim 1, wherein said hub is made of
one piece machine from any structural steel that includes the
toughening by forging, cold working, rolling casting, or other
similar metalworking process.
4. The mortar base plate of claim 1, wherein said ribs are formed
of maraging Steel or any structural steel including the toughened
by forged, cold working, rolling casting or the like.
5. The mortar base plate of claim 4, wherein said ribs are
connected into a joint formed within said hub, wherein said
articulating joint operatively allows for a transfer of impact
force energy such that said ribs have a `shock absorber` effect in
cushioning said hub.
6. The mortar base plate of claim 4, wherein said casing encases
distributes and dampens force throughout the base plate.
7. The mortar base plate of claim 7, wherein said ribs are formed
of maraging steel, or any structural steel including the toughened
by forged, cold or TITANIUM and to achieve the weight
reduction.
8. The mortar base plate of claim 1, wherein each said rib further
comprises: a first radially extended leg member opposite a second
radially extended leg member; an arcuately opposed receiving joint
formed between said first leg member and said second leg member;
wherein said receiving joint allows for a transfer of impact force
energy such that said ribs have a `shock absorber` effect in
cushioning said hub.
9. The mortar baseplate assembly of claim 1, wherein said
stabilizer pad adapted to be reversible useable and having a top
surface and a bottom surface, wherein said top surface is
configured for engagement with a first ground surface condition and
said second surface is configured for engagement with a second
ground surface condition.
10. A modular mortar baseplate assembly comprising, in combination:
a ball socket for receiving and retaining a cannon of an otherwise
conventional mortar; a support leg structure operatively connected
to and supporting said ball socket; and a stabilizer pad in
physical communication between said support leg structure and a
support surface for transferring a mortar recoil force from said
cannon to said support surface.
11. The assembly of claim 10, wherein said ball socket is fastened
to said support leg structure by threaded fasteners or rivets, and
thereby adapted to be readily replaced for maintenance or repair as
required.
12. The assembly of claim 10, wherein said support leg structure
comprises a structurally engineered multi-legged unit, wherein each
support leg comprises a characteristic of a spring for absorbing
and distributing a recoil force of the mortar.
13. The assembly of claim 12, wherein said support leg structure
forms a 6-legged hexagonal pattern.
14. The assembly of claim 10, wherein said stabilizer pad act as a
hysteresis damper and integrates with said support legs and
terminates at the ground in a ring configuration.
15. The assembly of claim 14, wherein said stabilizer pad is formed
of a material selected from the group comprising: synthetic
rubbers; thermoplastic rubbers; and urethanes.
16. The assembly of claim 15, wherein said stabilizer pad adapted
to be reversible useable and having a top surface and a bottom
surface, wherein said top surface is configured for engagement with
a first ground surface condition and said second surface is
configured for engagement with a second ground surface condition.
Description
RELATED APPLICATIONS
[0001] The present application incorporates subject matter that was
first disclosed in U.S. Provisional Application 61/182,455 filed on
May 29, 2009 and U.S. Provisional Application 61/239,219 filed on
Sep. 2, 2009, which are incorporated by reference herein as if
fully rewritten. There are no previously filed, nor any co-pending
applications, anywhere in the world.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to lightweight
mortar projectile guns and, more particularly, to an improved
architectural design for a motor base plate.
[0004] 2. Description of the Related Art
[0005] Lightweight gun systems are being widely used in current
military operations. The lighter the gun, the greater the mobility
and versatility in maneuvering the military force has. This is of
an advantage where the gun systems must be transported quickly, or
to difficult terrains or climates. Modern mortar systems have been
an effective means of force suppression since the trench warfare of
WWI. Their evolution over subsequent years has led to improvements
in safety, range, and lethality. A recent unclassified debriefing
from soldiers in Afghanistan noted that mortars were "essential"
due to the distance and elevation to targets in the mountainous
terrain, and that "mortars were responsible for many kills".
[0006] Mortars and their ammunition are smaller and lighter than
other artillery, making them ideal for support of movement to
contact, ambush, retrograde, and other deployment maneuvers. Their
"lobbing" trajectory can place their munitions on target over
obstacles and to positions at higher elevations than the position
of the mortar. The smooth bore of the mortar tube eliminates loads
created by the rifling of a gun tube, allowing mortar rounds to
carry higher payloads in thinner skins than artillery shells, thus
providing a greater explosive source than similar sized
artillery.
[0007] Unlike artillery pieces such as howitzers and cannon,
mortars need no complex recoil equipment and are usually smoothbore
and muzzle-loaded. The recoil force of the mortar is transferred
directly into the baseplate and from there into the ground. The
metal baseplates are relatively heavy: [0008] M7 baseplate for M224
60 mm mortar--14.4 lbs [0009] M3AI baseplate for M252 81 mm
mortar--29 lbs [0010] M9 baseplate for 120 mm mortar--136 lbs
[0011] FIG. 1 illustrates a 120 mm mortar assembly currently in
use. Mortar assembly 2 includes barrel 4, breech piece 5, bipod 6,
and base-plate 8. Barrel 4 is angled up and down to shoot the round
at the desired trajectory. The lower end of the barrel 4 is
externally threaded to take the breech piece 5. The breech piece
holds the striker. The striker is a fixed stud on which the bomb
falls under gravity. The lower end of the breech piece is shaped
into a ball (not shown) which enters a socket in the base plate
8.
[0012] Bipod 6 functions as a support and means to adjust the angle
of trajectory. This is achieved by adjusting the angle that barrel
4 makes with the ground. It also provides the means to hold barrel
4 at a proper angle. Base-plate 8 is a heavy welded steel dish. It
has socket 10 at the center to take the breech piece. This provides
the capability to rotate the barrel 4 around a full 360 without
shifting the base-plate.
[0013] Similar to base-plate 8, barrel 4 and bipod 6 are also made
of steel. Current mortars take advantage of important attributes of
steel. However, there are disadvantages associated with the use of
steel as the main material for manufacturing the mortars. For
example, 81 mm and 120 mm mortars made of steel are very heavy and
require a team to transport each piece. Typical prior art 120 mm
mortars weigh between 272 kg and 341 kg in the traveling
configuration. This creates problems when these mortars can no
longer be carried by machine and must be carried by humans. In
these situations, the 120 mm mortars must be dismantled and
transported part by part. This requires at least 3 to 4 people to
carry all the parts. Furthermore, in situations where time is of
the essence and the rounds must be fired continuously, dismantling
and re-assembling the mortars may not be practical.
[0014] Another problem with the current 120 mm mortars is that
there is no mechanism to reduce the recoil force and absorb the
recoil energy of the mortar assembly after each round is fired.
Presently, sand bags are placed under and around base-plate 8 to
absorb the recoil movement of mortar 2. Despite this, present 120
mm mortars on a non-absorbing surface may jump as high as 3 to 4
feet off the ground. This poses a clear danger to the mortar
operators. As a consequence, mortars are either placed on absorbing
surfaces such as soft ground or sandbags and may have extra bags
placed on the mount to reduce rebound effects. The recoil problem
is even greater with a light mortar such as the mortar of the
present invention.
[0015] Previous attempts at achieving weight reduction have focused
on simple material substitution, without significant structural
changes in design to effect a meaningful weight reduction. In
addition, the materials presently used in the mortar base plates
are susceptible to stress corrosion cracking due to the combination
of operating environments and residual stresses created during
manufacturing processes or stresses encountered during
operation.
[0016] Consequently, a need has been felt for providing an mortar
gun system having a light weight, portable base plate capable of
withstanding repeated, substantial recoil force and absorb the
recoil energy of the gun system caused by firing rounds.
SUMMARY OF THE INVENTION
[0017] It is therefore an object of the present invention to
provide an improved motor base plate capable of handling recoil
impact stress to achieve all the military qualification stress
levels for all available mortar base plates.
[0018] Features of the present invention are provided in an
architecturally design mortar base plate that is light weight, and
cost effective and size insensitive such that it can be adapted to
meet any available mortar base, such as 60 mm, 81 mm, 120 mm or any
size between.
[0019] Briefly described according to one embodiment of the present
invention, an architecturally design mortar base plate is provided
having a forged metal frame structure having a center receiving hub
and socket made of one piece machine from solid maranging steel,
4140 Steel, or any structural material for socket to absorb the
impact over repeated cycling. A plurality of metal ribs extend
radially out therefrom to distribute the impact strength from the
socket regime to throughout the whole base volume to consume the
energy that created due to firing. The metal ribs interconnect in
an interlocking, nested, mounted, bonded or welded manner to
support the socket in a position that is repeatable after firing.
The ribs further are architectural designed to minimize weight
while maintaining maximum desired strength.
[0020] Advantages the present invention result from the optimizing
of strength in a manner in which the overall material volume is
reduced, thereby reducing the total weight of the mortar base plate
itself. The required strength comes from the choice of material and
composite design. The whole design is based on eliminating stress
corrosion or any weakening mechanism of the existing bulk materials
that are used for such hardware. The mortar base is designed such
way that the critical cracks are engineered not to grow and
controlled by the geometry, several and different material choice
and engineered design to eliminate or minimize the crack formation
and crack growth during life of the base plate.
[0021] Further, the use of the "spider" configuration and
stabilizer pad provides a platform that dynamically attenuates the
force of the mortar recoil over time in much the same manner as
recoil adapters on aircraft mounted gun systems. This reduction of
load during the firing period will provide a more stable firing
platform in soft ground or snow conditions.
[0022] Further still, the structural design and material properties
of the improved baseplate will substantially increase the useful
life of this mortar system component compared to the existing
aluminum and other potential substitute materials by utilizing a
more impact compliant structure with a configuration that
eliminates high stress-concentration members such as gussets.
[0023] Additionally, it is a goal of the program that the proposed
mortar baseplate design, with replaceable, interchangeable 60 mm
and 81 mm ball sockets, will be strong enough and light enough to
replace both the M3A1 and M7 baseplates, thus significantly
reducing logistics costs.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The advantages and features of the present invention will
become better understood with reference to the following more
detailed description and claims taken in conjunction with the
accompanying drawings, in which like elements are identified with
like symbols, and in which:
[0025] FIG. 1 illustrates an example of a PRIOR ART mortar
system;
[0026] FIG. 2 is a perspective view of a support leg structure of
an architecturally design mortar base plate according to a
preferred embodiment of the present invention;
[0027] FIG. 3 is a top plan view thereof;
[0028] FIG. 4 is a cross sectional view taken along line IV-IV of
FIG. 3;
[0029] FIG. 5 is a top plan view thereof shown in conjunction with
a ball socket 14;
[0030] FIG. 6 is a cross sectional view taken along line VI-VI of
FIG. 5
[0031] FIG. 7 is partial perspective view of a ball socket 14 for
use in conjunction with the preferred and alternate embodiments of
the present invention;
[0032] FIG. 8 is a cross sectional view thereof;
[0033] FIG. 9 is a perspective view of an architecturally design
mortar base plate according to a first alternate embodiment of the
present invention;
[0034] FIG. 10 is a top plan view thereof;
[0035] FIG. 11 is a side elevational view thereof;
[0036] FIG. 12 is a side elevational view of the internal
structural skeleton for use therewith;
[0037] FIG. 13 is a cross sectional view taken along line XII-XII
of FIG. 11;
[0038] FIG. 14 is a detailed elevational view the internal
structural skeleton element for use therewith;
[0039] FIG. 15 is a top perspective view of a stabilizer pad 200
for use in conjunction with any embodiment of the present
invention;
[0040] FIG. 16 is a cross sectional view taken along line XVI-XVI
of FIG. 17;
[0041] FIG. 17 is a top plan view thereof;
[0042] FIG. 18 is a bottom perspective view of the stabilizer pad
200;
[0043] FIG. 19. Is a cross sectional view taken along line XIX-XIX
of FIG. 20;
[0044] FIG. 20 is a bottom plan view thereof;
[0045] FIG. 21 is a diagram of a Baseplate Assembly Loads During
Mortar Firing; and
[0046] FIG. 22 is a Finite Element Analysis of a Support Leg
20.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0047] The best mode for carrying out the invention is presented in
terms of its preferred embodiment, herein depicted within the
Figures.
1. Detailed Description of the Figures
[0048] Referring now to FIG. 2-8, an architecturally design mortar
base plate 10 is shown according to the preferred embodiment of the
present invention for use in conjunction with the M252 81 mm
mortar. The base plate 10 is designed to replace base plate 8 of
the PRIOR ART as shown in FIG. 1. FIG. The base plate 10 is formed
of a composite architectural structure having a center receiving
hub 12 and forming a connection point for a socket 14. The hub 12
is made of one piece machine from one piece machine from solid
maranging steel, 4140 Steel, or any structural material for socket
to absorb the impact over repeated cycling. A plurality of
optimized metal ribs 20 extend radially out from the hub 12. The
ribs 20 are forging integrally to shape metal by using localized
compressive forces. Such forging additionally decreases corrosion
or stress cracking weaknesses by eliminating voids in the material
that facilitate such weaknesses or failures. As would be obvious to
a person having ordinary skill in the relevant art, in hindsight of
the teachings and benefits disclosed by the present invention, the
present invention can be readily adapted to cold forging, warm
forging or hot forging. Cold forging is done at room temperature or
near room temperature. Hot forging is done at a high temperature,
which makes metal easier to shape and less likely to fracture. Warm
forging is done at intermediate temperature between room
temperature and hot forging temperatures.
[0049] The primary support of the baseplate consists of a
structurally engineered multi-legged unit. The design concept shown
in FIG. 3 is an illustrative example of the supports forming a
6-legged hexagonal pattern. Other patterns involving different
numbers of legs, and some leg angles of unequal values, will be
considered during the initial evaluation.
[0050] The structural design of the support leg structure 10 gives
it the characteristics of a spring, which will absorb and
distribute the recoil force of the mortar. The legs will be
fabricated from materials that optimize the weight to stiffness
ratio for the application. While maraging steel is known to possess
superior strength (typically 3 times greater than that of
heat-treated alloy steel, such as 4140), toughness, and
malleability, characteristics that provide the least weight for a
given strength. Non-stainless varieties of maraging steels are
moderately corrosion-resistant, and resist stress corrosion and
hydrogen embrittlement. Additional corrosion protection is gained
by cadmium plating or phosphating. Another unique characteristic of
the maraging steel is that even though it has a very high yield
strength and fracture toughness, the fracture mechanism is ductile
which is very unique property of the material. This characteristic
of the steel enables engineers to design critical structures--such
as ballistic missile skins--that are significantly lighter and
stronger than with other materials.
[0051] Fabrication of the support leg structure will consist of
machining a flat pattern of the structure from steel plate. The
part will then be press-forged into its final shape.
[0052] It has been found that the functional requirements for the
mortar baseplate include: transmitting the recoil force to ground
in a manner that does not shift the mortar cannon prior to exit of
the projectile; withstanding the recoil of a minimum of ten
thousand rounds without permanent deformation, fracture, or other
failure modes; and, operating in specified environmental extremes
of temperature, humidity, precipitation, particulates, etc. A
typical force-time curve for a projectile launched by a
non-progressive propellant is shown in Table 1.
The force-time curve can be generated analytically if the
projectile and cannon properties are known, along with the
propellant type and amount of charge, by using the law of
combustion, energy conservation law, and the equation of motion for
the projectile. Alternatively, it can be established from test
results. The area under the force-time curve represents the linear
impulse generated by the firing of the mortar and must be absorbed
by the mortar baseplate without interfering with the ballistic path
required to place the round on target.
[0053] As shown best in conjunction with FIG. 5-6, the ball socket
14 is the interface between the mortar cannon and the baseplate 10.
For purposes of disclosing the preferred embodiment, and not
intended as a limitation, the ball socket 14 can be of the same or
similar design as that of the current 81 mm baseplate socket in
terms of rotation for alignment with the baseplate stake, insertion
of the breech plug, and locking of the barrel. Rather than being
machined into the baseplate, the socket 14 can be fastened to the
support leg structure 10 by threaded fasteners or rivets, and
readily replaced at the organizational maintenance level if need
be.
[0054] Referring now to FIG. 9-14, a first alternate embodiment of
an architecturally design mortar base plate 110 is shown according
to the present invention. The base plate 110 is also designed to
replace base plate 8 of the PRIOR ART as shown in FIG. 1. The base
plate 110 is formed of a composite architectural structure having a
center receiving hub 112 and forming a socket 114. The hub 112 is
made of one piece machine from one piece machine from solid
maranging steel, 4140 Steel, or any structural material for socket
to absorb the impact over repeated cycling. A plurality of
optimized metal ribs 120 extend radially out from the hub 112 and
interlock to form a connection joint 122. The ribs 120 are forging
to shaping metal by using localized compressive forces. Such
forging additionally decreases corrosion or stress cracking
weaknesses by eliminating voids in the material that facilitate
such weaknesses or failures. As would be obvious to a person having
ordinary skill in the relevant art, in hindsight of the teachings
and benefits disclosed by the present invention, the present
invention can be readily adapted to cold forging, warm forging or
hot forging. Cold forging is done at room temperature or near room
temperature. Hot forging is done at a high temperature, which makes
metal easier to shape and less likely to fracture. Warm forging is
done at intermediate temperature between room temperature and hot
forging temperatures.
[0055] Forging results in metal that is stronger than cast or
machined metal parts. This stems from the grain flow caused through
forging. As the metal is pounded the grains deform to follow the
shape of the part, thus the grains are unbroken throughout the
part.
[0056] The forged ribs 120 distribute the recoil and impact
strength from the socket 112 to throughout the whole base volume to
consume the energy that created due to firing. Alternately, as
taught by the related applications referenced above, Kevlar.RTM. or
structural fabric webs 124 can be affixed additionally between the
ribs 120 shares the recoil impact energy to each rib 120 and
polymer body.
[0057] Referring now to FIG. 15-20, a stabilizer pad 200,
anticipated as being formed of a polymeric material, is intended
for use in conjunction integrally with any style baseplate 10, 100,
and will ultimately transfer the mortar recoil force to ground. The
stabilizer pad 200 will act as a hysteresis damper component in the
baseplate assembly. The stabilizer 20 pad will be integrated with
the support legs and will terminate at the ground in a ring
configuration 202. Although shown in FIG. 15-20 as a solid wall
structure, other configurations--such as wall cut-outs to reduce
weight--are anticipated as obvious improvements of the functions
and features described herein. A person having ordinary skill in
the relevant art, in light of the present teachings, will be able
to evaluated the effects of such modifications on baseplate
performance.
[0058] It is anticipated that the stabilizer pad 200 is made of a
polymeric material, including synthetic rubbers, thermoplastic
rubbers, urethanes, etc. In addition to the physical properties
required to withstand environmental and operational conditions, key
material characteristics will also include the necessary
coefficients of stiffness and damping that will lead to an
effective mortar baseplate unit.
[0059] Given the present teachings and findings, additional
functional elements are anticipated within the present invention.
Horizontal leg stringers may be added to the leg support structure
in order to distribute the transverse force created by the
elevation angle of the mortar to each of the support legs and
ultimately to the stabilizer pad. The leg stringers will be
fabricated from flexible high strength, low elongation material,
such as aramid, to minimize weight. The locations, material
requirements, and effectiveness of the stringers will be evaluated
during design analysis.
2. Operation of the Preferred Embodiment
[0060] In accordance with a preferred embodiment of the present
invention, the ribs 20 are connected into a joint 26 within the hub
12. The joint 24 is designed to allow for a transfer of motion
along with any impact force such that the ribs 10 have a `shock
absorber` effect in cushioning the hub 12. The ribs 20 thereby
distribute and dampen this force throughout the structure, and
allow for the hub 12 to move back to its original position after
firing.
[0061] The loading on the baseplate assembly under such conditions
is shown in FIG. 21. The resultant loads on the baseplate assembly
in the z-direction can be accurately modeled by a straightforward
spring and damper system, which yields an equation of motion
of:
F-Reaction(t)=knzn(t)+cnvn(t) (1)
Where:
[0062] F-Reaction(t) is the reaction force between the baseplate
system and ground (This force will be variable over time based on
the linear impulse from the mortar, and will have a planar
distribution on the stabilizer pad);
[0063] kn is the equivalent spring constant of the support legs and
stabilizer pad;
[0064] zn(t) is the displacement of the support legs and stabilizer
pad over time;
[0065] cn is the damping fact& of the support legs and
stabilizer pad; and
[0066] vn(t) is the velocity the support legs and stabilizer pad
over time.
In the transverse, or x-direction, the spring-damper
characteristics are expected to be less of a factor, and the
resistance to the recoil force and overturning moment will be
reacted by friction between the stabilizer base and ground, and the
weight of the mortar system.
[0067] A preliminary finite element analysis performed on the
initial concept shows the level of the von Mises stress in one
support leg in FIG. 22. This initial concept was based on a
rectangular cross section of AISI 4140 alloy steel subjected to
vertical loading only. The results show a deflection of 0.262 inch
and a maximum stress level of 32,000 psi, well below the 130,000
psi yield stress of heat-treated 4140 steel.
[0068] The foregoing descriptions of specific embodiments of the
present invention have been presented for purposes of illustration
and description. They are not intended to be exhaustive or to limit
the invention to the precise forms disclosed, and obviously many
modifications and variations are possible in light of the above
teaching. The embodiments were chosen and described in order to
best explain the principles of the invention and its practical
application, to thereby enable others skilled in the art to best
utilize the invention and various embodiments with various
modifications as are suited to the particular use contemplated. It
is intended that the scope of the invention be defined by the
Claims appended hereto and their equivalents. Therefore, the scope
of the invention is to be limited only by the following claims.
* * * * *