U.S. patent number 3,721,096 [Application Number 05/066,985] was granted by the patent office on 1973-03-20 for soft support system for hulls and the like.
Invention is credited to Frederick J. Brinkmann, Albert V. Deckert, Jr..
United States Patent |
3,721,096 |
Deckert, Jr. , et
al. |
March 20, 1973 |
SOFT SUPPORT SYSTEM FOR HULLS AND THE LIKE
Abstract
A "soft" support system, preferrably utilizing pneumatic
bellows, capable of supporting a ship hull in a relatively level
condition on its building foundations or ways during construction
and during moving operations; the system uses either a dynamic or a
static "soft" support insert between the basic "hard" foundation
supports and the vessel shell; in addition to the preferred
pneumatic bellows the "soft" support insert could be inter alia a
hydraulic, steel or rubber/elastomeric "spring"; the system in its
dynamic mode is capable of raising, lowering or leveling the ship
hull, or in minutely positioning hull sections to be joined
together during construction operations; the system effectively
distributes all loads and reactions between the hull and the
foundation or ways thereby tending to eliminate unequal elevations
of the foundation or way support locations and tending to nullify
hull movement effects due to welding stresses and/or temperature
changes, thereby tending to provide a constant support system;
during moving operations across the foundations or ways, the
constant support system will more nearly allow the horizontal
pushing force requirements at each support location to equalize;
the preferred embodiment of the "soft" support element includes a
series of pneumatic bellows units, each unit including a set of
three rubber bellows fastened between two opposing plates, the
pneumatic pressure in the bellows being variable, system control
for the pneumatic pressure can be a simple manual operation or can
be highly sophisticated.
Inventors: |
Deckert, Jr.; Albert V. (New
Orleans, LA), Brinkmann; Frederick J. (Metairie, LA) |
Family
ID: |
22073002 |
Appl.
No.: |
05/066,985 |
Filed: |
August 26, 1970 |
Current U.S.
Class: |
405/7; 114/54;
267/113 |
Current CPC
Class: |
B63C
5/04 (20130101) |
Current International
Class: |
B63C
5/04 (20060101); B63C 5/00 (20060101); B63c
005/04 (); F16f 015/16 () |
Field of
Search: |
;61/66,67,50,65F ;114/54
;52/2,293,745 ;248/22,350 ;267/113 ;61/66,67,50,45F |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
223,312 |
|
Nov 1958 |
|
AU |
|
250,689 |
|
1926 |
|
GB |
|
Primary Examiner: Shapiro; Jacob
Claims
What is claimed as invention is:
1. A pneumatic support system for supporting and/or moving a heavy
load, as for example a ship hull or the like, in the ambient
comprising:
a series of support unit means dispersed between the heavy load and
the ground for supporting at least part of said heavy load and for
equalizing forces occuring in the static supporting, positioning
and horizontal moving of said heavy load; each of said support unit
means comprising
a hard, rigid upper load-bearing member upon which said load is, at
least indirectly, partially carried, said upper member having a
lower, downwardly-directed facing surface having a multiple number
of facing areas thereon;
a hard, rigid, lower, load-bearing member, resting at least
indirectly upon the ground, said lower member having an upper,
upwardly-directed facing surface having a multiple number of facing
areas thereon which are located opposite the corresponding facing
areas of said upper member, said upper and said lower load-bearing
members being two opposed, flat plates disposed in at least a
generally parallel relationship;
a multiple number of "soft", pneumatic support elements dispersed
between and fixedly attached to said upper and lower load-bearing
members at and between their opposing facing areas, said support
elements serving to transmit the load from said upper to said lower
load-bearing member, said "soft", pneumatic support elements
comprising pneumatic air bag means for variably and continuously
equalizing any variations in the applied load between said support
unit means and for changing the relative positioning of the upper
and lower load-bearing members, said pneumatic air bags being
generally cylindrical in configuration and completely open at both
ends, said load-bearing members being flat at said facing areas and
closing off the ends of said air bags to create a closed, inner,
air-tight system with said air bags.
2. The support system of claim 1 wherein said air bags are fixedly
attached to said upper and lower load-bearing members by means of a
series of rim bolts placed about and through the facing periphery
of said air bag and bolted securely into said upper and lower
load-bearing members, whereby a defective air bag can be readily
and easily removed and replaced while that support unit is still
supporting the heavy load.
3. The support system of claim 1 wherein said flat plates each have
disposed thereon opposing bumper plates for limiting the amount of
minimum spacing between the plates to protect the air bags fixed
therebetween.
4. The support system of claim 1 wherein at least one of said
plates includes integrally within it an air supply line feeding
into said closed, inner, air-tight system.
5. The support system of claim 1 wherein there is further included
dynamic fluid means attached to said air bags for independently and
individually varying the load-carrying characteristics of said
series of support units, said dynamic fluid means comprising a
pneumatic pressure control system.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a "soft" or resilient support
system for load leveling, positioning, cushioning and equalizing
stresses for ship hulls and other extremely heavy structures and
the like, which system can be either dynamic or static.
In the particular application described, the present invention
provides a unique system for supporting ship hulls during
construction or during hull movement or positioning of the hull
horizontally and/or vertically. The system of the present invention
gives continuous, resilient support to ship hulls during
construction similar to or approaching natural flotation, thereby
eliminating any high localized stresses at support locations. The
invention also permits horizontal movement over irregular building
surfaces or ways without causing high, localized stresses on hull
or foundations and further allows linear and differential vertical
movement for positioning hulls or parts of hulls and for transfer
of a hull from longitudinal to transverse ways or vice-versa.
Either a dynamic system, using external means such as air or
hydraulic pressure, may be used, or a static resilient system
(elastic material) may be used, use of either system being
dependent upon application. Any degree of manual or automatic
controls may be employed to regulate or position the supported
loads of a dynamic system.
The technique of the prior art now being used for building ship
hulls and the like are remnants of ancient ship building practices
of starting with a member leveled with wedges and building thereon.
The resultant variations in foundation elevations as the loads were
increased during building were considered a part of the building
process and usually ignored. Also, heretofore a ship was usually
built in one location and launced directly from that location. Now,
however, competition in the industry forced other methods to be
tried and used, and an assembly-line type of construction of ship
hulls began where portions of hulls were constructed in various
locations and brought together to be joined into a single jull. The
assembled hull was then brought to a launch position.
The usual methods of hull support that evolved through the years
were employed over new horizontal land structures installed to
support the hull and hull sections in building and moving.
Particular difficulties were encountered in moving the heavy masses
horizontally and in positioning the various hull sections to be
joined. Unless the land structures over which the loads traveled
were perfectly even and did not deflect or change position in
relation to one another, and unless the hull was in perfect
alignment and not distorted due to temperature differential or
welding stresses, high, localized stresses occurred on hull support
components and land structures at their high points and highly
uneven horizontal push forces, resulting in numerous problems
including lost time and component failures. Also, in joining the
portions of hulls, the exact positioning of the section was an
arduous task of jacking, straining, and wedging, requiring much
time and skill.
The present invention provides a "soft", resilient support element
located between the "hard" hull support members and the "hard" land
structures, thereby providing an element to cushion and to tend to
equalize the loads and reactions which occur in a building position
or during moving operations, providing more nearly equalized
horizontal push-load requirements at each push location during
moving operations. In its dynamic mode, the present invention can
also provide leveling and positioning of loads in elevation, pitch,
and roll, this being especially useful in joining sections of hulls
or changing direction of horizontal hull movements. The control of
the elevation, pitch and roll of a dynamic system utilizing
compressed air or hydraulics can be simply manual or combined with
automatic components.
The support system of the present invention for hulls and the like
can be divided into two basic modes of operation, static and
dynamic; and each of these again divided into two basic divisions,
one position building and multi-position building requiring
movement.
a. The static system, single building position mode would use steel
or elastomeric springs of suitable deflection characteristics to
cushion and equalize the loads and reactions between hull and land
structures due to inequities in alignment, or to hull movement
and/or deflection, thereby assuring protection to the hull, support
components, and support structure.
b. The static system, multi-position building mode would use steel
or elastomeric springs as in (a) above and would provide the above
features in addition to equalizing the loads over emmense land
structures during moving operations.
c. The dynamic system, single building position mode would use
pneumatic or hydraulic devices to provide results as above in (a)
in addition to better equalization of reactions due to hull or land
structure movements or inequalities.
d. The dynamic system, multi-position building mode would use
pneumatic or hydraulic devices as in (c) above and would provide
all the above features in (a), (b), and (c) in addition to
positioning capabilities.
The above listed four exemplary basic modes of course do not
preclude other modes or combinations of these modes.
The static system requires no outside power or system controls; the
dynamic systems do require some outside source of pressure and at
least a basic control system for control.
The preferred embodiment of this invention uses the mode of
operation listed in (d) above, using a pneumatic device to provide
for ease of control and use of a usually ready source of plant
compressed air. The pneumatic device considered here is a
commercially available reinforced rubber bellows or pillow capable
of the pressures necessary to support the required loads.
As noted above, the present invention has particular value as
applied to a method or system to aid in evenly distributing the
load of a ship onto its building foundations or ways and of
leveling or changing the position of sections of vessels to be
joined together during construction. Such methods have become
increasingly important to the shipbuilding industry as larger and
larger vessels have been constructed, and as existing building
foundations or ways have become more uneven because of these
heavier loadings, thereby causing difficulties in moving hulls from
one building position to another and where hull loads transmitted
to the foundations must be maintained not to exceed a certain
limit.
The magnitude of the situation can be better understood with the
realization that whole ship hulls, shell structures or sections
thereof, weighing thousands of tons, must be moved horizontally
across extensive land structures (building ways) to various
building positions or locations, particularly in the assembly-line
method of ship construction which is now being practiced in the
industry.
Heretofore, the basic system for distributing and leveling the load
in any given building position that has been used in the industry
has been a series of wedges between the fixed timber or steel
supports or cradles upon which the vessel rides. However, each such
support or cradle constituted individually a "hard" support, i.e.
one which had little or no resiliency or variability to it. Thus a
support was either in full contact with the load and hence carried
its full load, or it was out of contact and carried no-load, there
being little or no flexibility to it.
Because of the "hard" support nature of the prior art systems, many
difficulties have arisen. Particularly when the vessel shell
structure or portions thereof are attempted to be moved
horizontally across the land structures or building ways in the
assembly-line method of construction, alternate light and severe
push loads were often encountered at support locations because of
varying reaction forces. Although it would be physically possible
to overdesign the pushing jacks moving the structure horizontally
to be able to overcome the heavy loads, an arrangement to provide
for such a wide load fluctuation is highly undesirable.
It has been determined by observation and by elevation readings
before and when the load was applied that this condition is caused
by differential loading along a building way and between adjacent
ways, stemming apparently from the following primary causes:
1. Differential elevation and/or subsidence along and between ways;
and
2. Inability of the hull to conform to the inequalities of the
foundation elevations; and
3. Certain hull movements and distortions due to welding stresses
and to differential temperatures changes in the hull structure.
This unequal distribution of loads results in bearing pressures on
some ways far above the way design loads, causing structural
failure of the way members in some instances and increasing
friction loads on those ways which are carrying all or part of the
load intended to be borne by an adjacent way, which is then in a
sense taking a "free ride".
In addition to the above-mentioned undesirable conditions, the
slide timber on the lightened way has in some instances been pushed
by the jacks in relation to the cradles, leaving a portion of the
ship without support and requiring repositioning of the shifted
members. Attempts have been made to remedy this condition in some
applications by installing struts from the jacking head of the
slide timber to a bearing plate on the hull. While this has been
successful in preventing differential timber movement, there are
undesirable side effects such as overloading the hull shell on a
relatively small area and the vertical component of the reaction
from the strut forcing the jacking head down against the surface
plate on the ways, causing gouging and increasing resistance to
pushing.
While these side effects may be eliminated or reduced by
modification of the strut ends, it becomes apparent that a system
of maintaining uniform unit loads over the entire area of ways
under the load would completely eliminate the entire problem.
In addition to uneven building ways, the hull structure wants to
assume a different shape longitudinally as temperature
differentials may affect the top and bottom and as welding stresses
are introduced into the structure, making it bend slightly in one
direction or another. The deflections due to temperature is
temporary and variable; the deflections due to welding stresses are
permanent. These movements affect the reaction forces and cause
localized stress on supports effected.
Systems of supplemental support jacks and/or wedges have also been
proposed to help level out the inequalities of the building ways,
but these would require constant attention as the hull moves across
the uneven ways, a perhaps workable system, but ardous in control.
Moreover, each of the systems of jacks or wedges again involve
individually "hard" supports.
The present invention, on the other hand, contemplates instead the
use of a series of "soft" supports, i.e., ones which can carry any
variation or degree of the load as desired. The present invention
in the preferred embodiment achieves this by in effect inserting a
series of pneumatic "spring" units, whose tensions preferably can
easily, completely and individually be varied, between the load and
each support.
The system of the present invention distributes the load of the
ship onto the building foundation or ways more evenly and
eliminates hard spots that would tend to bind and retard motion
during moving operations, or prevent the overload of support
members and their possible failure.
A basic advantage of the present invention over the prior art is
the provision of a soft, resilient, spring-like structure support
system that naturally tends to offer some measure of support
irrespective of variations in way elevation, hull distortion, or
air pressure.
The present invention achieves this "soft" or "spring" support by
several types of systems among which are:
a. direct acting pneumatic bellows manifolded to a source of air
pressure through regulators (the preferred embodiment);
b. direct acting hydraulic jacks or hydraulic jack operated wedges
manifolded to multiple central hydraulic systems with
accumulators;
c. actual, large heavy duty steel springs; and
d. large, heavy duty rubber or elastomeric "springs".
Of the systems of the present invention, the direct acting
pneumatic bellows system using standard plant air pressure as a
power source is the most workable and easily controllable system,
is considered the preferred embodiment and hence will be described
in detail.
The usual availability of plant air pressure and ease of control
through regulating air supply pressures to the bellows greatly
enhances the great value of the preferred embodiment. The pneumatic
system compares favorably with the advantages of the other systems
of the present invention but in addition has the advantages of
simplicity, practically frictionless operation, ready power source
(plant air), ability to measure actual loads, and ease of
control.
The present system unlike the prior art gives continuous resilient
support to ship hulls and sections during construction thereof
similar to natural buoyancy or flotation. It allows horizontal
movement over irregular building surfaces or ways without causing
high, localized stresses on the hulls, support components, or the
support members. It further allows linear and differential vertical
movement for position hulls or sections and for easy transfer of a
hull from one set of ways to the other. It also allows distortional
movements of the hull shell without overloading the foundations or
the shell itself.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of an assembly-line type shipbuilding
facility wherein the present invention can be applied to particular
advantage;
FIG. 2 is a perspective view of the support system of the present
invention as applied to a ship being moved across ways;
FIGS. 3 and 4 are side and top, plan views, respectively, of a
support unit of the present invention.
FIGS. 5 and 6 are side, cross-sectional and top, plan views,
respectively of a pneumatic bellow which can be used in the present
invention;
FIG. 7 is a schematic diagram of a pneumatic, manually operated
control system which can be used in the present invention; and
FIGS. 8A - 8D are generalized representations of alternative types
of "soft" or resilient "spring" or support elements which can be
used in the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Because of the need to economize in shipbuilding, the shipbuilding
industry has been adopting the technique of continuous,
assembly-line fabrication of ships. An example of the adoption of
this technique is found in the Ingalls shipbuilding facility of
Litton Industries in Pascagoula, Mississippi, a portion of which is
generally illustrated in FIG. 1.
In this technique preliminary preparation of the materials and
subassembly work is done in a continuous process (note arrows). As
shown in FIG. 1, the sub-assemblies are welded together into
complete sections or modules 1 of the ship being built. Each module
1, in this instance weighing 1,500 to 2,100 tons, is moved down the
longitudinal building ways or tracks 2 as it is being completed.
Upon completion of each module - section 1, the modules 1 are
brought into the lateral building ways or tracks 3 to the
integration area and mated together to form the completed ship 4.
To launch the ship 4, now approximately 92 percent complete, it is
moved on lateral and longitudinal building ways or tracks onto the
launch pontoon 5. After replacing the wingwalls 6, the launch
pontoon 5 is moved into the ship channel and submerged, launching
the ship 4.
As is apparent, a great deal of moving and positioning of extremely
heavy (hundreds and thousands of tons) objects is involved in this
technique. It is in this moving and positioning of these extremely
heavy objects (ships, module sections and the like) that the
support system of the present invention is applied.
As is well known in the art, horizontal movement of these heavy
loads can be accomplished by sliding action (a slide member on a
lubricated way member) or by some force of rolling action (roller
bearings or wheeled members). Horizontal push forces are applied to
each transverse or longitudinal support member to effect the
horizontal movement; the nature and application of these forces are
dependent on the user's choice.
As illustrated in FIG. 2, the preferred embodiment of the support
system of the present invention as applied to an extremely heavy
object such as a ship 4 comprises a series of "soft" or resilient
supports 7 including a row of pneumatic air bellows 8 situated
between the top of each slide timber 9 of the building ways 2 - 3
and the bottom of each hull cradle 10. Although only three sets of
"soft" supports 7 are illustrated for simplicity sake, in actual
practice a full set of "soft" or resilient supports 7 would be used
at each way or support location.
The "soft" or resilient supports 7 can be provided in basic units
11 of three bellows 8 each (note FIGS. 3 and 4), capped top and
bottom with steel plates 12 and 13, respectively. As it is
necessary that the faces of the bellows 8 be separated by at least
3 1/2 inches when in a closed position, 2 inch high bumper blocks
14 on the inside face of each plate are provided.
The bottom plate 13 is edge drilled for air supply to each bellow
8, while rim bolt holes 15 for attaching the bellows 8 to the
plates 12 and 13 are countersunk to present a smooth outside
surface. The bellows 8 are strong enough to support the weight of
one plate when suspended by the other plate. The bellows are also
strong enough to withstand relatively high air pressures without
load or restraint, however this procedure is not recommended as the
bellows 8 could be damaged and appropriate maximum pressure
restraints should be provided for safety.
The flexible body 16 of the circular pneumatic bellows 8 can be of
a nylon-tire-cord reinforced rubber such as neoprene, a suitable
commercial bellows being sold under the trademark "Airmount" (Model
No. 211-A) by the Firestone Industrial Rubber Products Co. Each
bellows 8, as illustrated in FIGS. 5 and 6, includes a metal
mounting or bead rim 17 with mounting bolts 18 at its top and
bottom for attachment to the plates 12 and 13. In the event any
bellows is damaged or otherwise made unusable, it can be removed
and another inserted at any time by removing the bolts 18 holding
the rim 17 to the plates 12 - 13.
Suitable dimensions of the bellows 8 for this application are
approximately 9 inches in height and 28 inches in diameter when
expanded to working elevation. The bellows 8 have varying load
capacity with varying air pressure with high capacity at high air
pressures and low capacity at low air pressures. As is true of
bellows in general, external means may be employed for greater
lateral stability.
The pneumatic bellows are relatively maintenance free and
frictionless in operation. Minor leaks in the air system are of
small consequence, particularly when air supply exceeds leak rate.
Bellows life should be long (10 years service is anticipated);
however, physical damage to the bellows in this environment must be
considered in the total life picture.
In order to control the positioning of the load, for example ship
4, a pneumatic pressure control system can be used (note FIG. 7).
Small groups of air bellows 8 on each building way, for example two
to six units 11, are individually manifolded to a suitable supply
of air pressure which can be manually regulated. The total support
forces can be regulated on each building way or on portions of a
way. The hull 4 can be lifted or lowered or tilted as required
through coordinated control of the air supplies at each way or
support. During moving operation, the unevenness of the ways are
absorbed by the combined bending of the slide timber 2 - 3 and the
flexibility of the pneumatic bellows 8, and constant support forces
can be attained by manual regulation of air pressures to the
bellows 8 during this operation.
When the vessel 4 is in a building position, wedges or other
adjustable support devices such as jacks or other "hard" supports
can be inserted to support the loads, and the bellows 8 can be
deflated to a few pounds pressure to effect a soft-skin condition.
This soft-skin condition will help guard against accidental
puncture of the rubber material 16.
The supplemental support by wedges, etc. and reductions of air
pressure to a soft-skin condition is not necessary, but is an
option of the user. A continuously inflated system does have the
advantage of continuously equalizing changing loads transmitted to
the supports or foundations during building, e.g., those due to
hull distortions caused by temperature changes or welding stresses.
In this instance however the bellows 8 are inflated and pressure
regulated as required for lifts or positioning and during moving
operations, but during static building operations the pressure in
the bellows is reduced to a few pounds to effect the soft-skin
condition.
Most shipyards have air pressure systems already as part of their
facilities, these systems normally being of the order of 100 - 200
psi. The bellows 8 of the present invention work well on the 100
psi in the instance described and hence usually require no
additional pressure source. However, if the basic plant pressure is
below or only near the bellows operating point, supplemental
compressors can be used. Adequate air pressure should be provided
because a pressure reserve is necessary for the system to maintain
positive system control. If a lower air pressure is used,
additional bellows will be required as the load capacity is a
directly related foundation of the pressure. Greater lifting
capacity is of course achieved by increasing the number of bellows
8, or increasing the working pressure.
Control of the lifting, lowering and leveling of the load can be
achieved by a manual operation with manned control locations at
each cradle 10, or building way or support 2 - 3. Each control
location can consist of an air piping manifold including valves,
gauges, and air pressure regulators. Central control and
coordination of the whole pneumatic operation can be accomplished
through "walkie-talkie" communications to each cradle or support
control location.
When a load is ready to be moved, the bellows 8 are pressured and
the load raised from any physical support, which is then removed or
lowered to provide clearance for the move across the uneven ways or
supports 2 - 3.
As the move progresses, it is anticipated that each cradle or
support control station be manned and the air pressures on each
manifold be kept as closely as possible to the design pressure in
order to best equalize the reaction forces transmitted to the slide
timbers, and to maintain the load in as level a condition as
possible. Although a simple manual system of control has been
indicated, any degree of sophistication of control can be achieved
through many presently available pneumatic instrumentation
components.
As is apparent, the ease of control of the "soft" or resilient
"spring" system of the present invention for moving, raising and
lowering is highly desirable and advantageous. Indeed the system's
ability to tilt the load in elevation, pitch or roll to match up
sections being assembled together is unique.
Although the invention has been described with particular reference
to the moving and positioning of ships and hull sections, its
general application for lateral movement of any large masses
involving loads of hundreds and thousands of tons over land
structures is excellent. Moreover, although a particular air bag is
described in detail, other resilient or "soft" support members
might be used such as a hydraulic "spring" (FIG. 8A), a steel
spring (FIG. 8B) or a rubber or elastomeric "spring" (FIG. 8C) or a
different form of air "spring" (FIG. 8D).
The static embodiments of FIGS. 8B and 8C have a counter-reaction
to a load (communicated through plate 12) proportional to their
deflections, this being a physical property of the support
material. The dynamic embodiments of FIGS. 8A and 8D can of course
give support reactions similar to that of FIGS. 8B and 8C when
their fluid medium is static. However, when the internal fluid
pressure or volume is changed through external means, the support
reactions also change as well as the support elevations.
Because many varying and different embodiments may be made within
the scope of the inventive concept herein taught, and because many
modifications may be made in the embodiment herein detailed in
accordance with the description requirements of the law, it is to
be understood that the details herein are to be interpreted merely
as illustrative and not in a limiting sense.
* * * * *