U.S. patent number 3,890,757 [Application Number 05/446,593] was granted by the patent office on 1975-06-24 for boom members having stiffener elements for crane boom constructions.
This patent grant is currently assigned to J. I. Case Company. Invention is credited to Terry M. Holmes, Gerald P. Lamer.
United States Patent |
3,890,757 |
Lamer , et al. |
June 24, 1975 |
**Please see images for:
( Certificate of Correction ) ** |
Boom members having stiffener elements for crane boom
constructions
Abstract
A multisection crane boom construction is disclosed herein. The
various boom sections are each formed of a plurality of members
which are interconnected in a unique fashion and are reinforced to
provide boom sections that have a high strength-to-weight ratio and
provide both vertical and lateral rigidity. Each boom section
consists of a pair of elongated channel members having webs and
flanges with the flanges being interconnected by connecting members
and the webs being reinforced by web stiffeners to increase the
buckling resistance of the web portions.
Inventors: |
Lamer; Gerald P. (Rothschild,
WI), Holmes; Terry M. (Schofield, WI) |
Assignee: |
J. I. Case Company (Racine,
WI)
|
Family
ID: |
23773167 |
Appl.
No.: |
05/446,593 |
Filed: |
February 28, 1974 |
Current U.S.
Class: |
52/695; 52/848;
52/632; 52/118 |
Current CPC
Class: |
E04C
3/08 (20130101); B66C 23/701 (20130101); E04C
2003/0413 (20130101); E04C 2003/0473 (20130101); E04C
2003/0434 (20130101); E04C 2003/0465 (20130101); E04C
2003/0452 (20130101) |
Current International
Class: |
E04C
3/04 (20060101); E04C 3/08 (20060101); B66C
23/00 (20060101); B66C 23/70 (20060101); E04c
003/08 () |
Field of
Search: |
;52/116,117,118,731,632,695,634,514 ;212/55 ;D12/54
;29/155R,155C |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
1,009,373 |
|
May 1957 |
|
DT |
|
31,498 |
|
Nov 1964 |
|
DL |
|
128,322 |
|
Jun 1919 |
|
GB |
|
417,212 |
|
Oct 1934 |
|
GB |
|
Primary Examiner: Abbott; Frank L.
Assistant Examiner: Braun; Leslie A.
Attorney, Agent or Firm: Dressler, Goldsmith, Clement &
Gordon, Ltd.
Claims
What is claimed is:
1. A boom for a crane or the like comprising an elongated hollow
member having a plurality of flat walls, at least one of said walls
having a plurality of openings spaced from each other, a stiffening
element located between each adjacent pair of openings, each
stiffening element having a central core generally aligned with a
longitudinal center line for said at least one wall and a plurality
of arms extending from said central core to the outer edges of said
at least one member, said stiffening elements being secured to a
surface of said at least one wall between said openings and
reinforcing the edges of said openings, and a plurality of buttons
each having a dimension greater than the dimension of said cores,
said buttons overlying respective central cores and being secured
to said surface.
2. A boom as defined in claim 1, in which said hollow member is
defined by a pair of elongated channel members, each having a web
portion and flanges at opposite edges of said web portion, said
channel members being positioned so that said web portions define a
pair of said flat walls and said flanges of respective channels
extend towards each other with free edges spaced from each other,
and a pair of interconnecting members connecting adjacent pairs of
flanges to define a further pair of said flat walls.
3. A boom as defined in claim 2, in which both of said web portions
have openings, stiffening elements and buttons as defined in claim
7.
4. A boom as defined in claim 3, further including elongated
reinforcing plates located adjacent the intersection of each flange
with its adjacent web portion.
5. A boom as defined in claim 4, in which said elongated
reinforcing plates include an angle iron at each intersection.
6. A boom as defined in claim 3, in which said stiffener elements
are generally X-shaped in plan view and said openings diamond
shaped to produce a semi-closed lattice boom construction.
7. A boom as defined in claim 1, in which said surface is an inside
surface of at least one of said walls of said hollow member.
Description
BACKGROUND OF THE INVENTION
For many years now, telescoping crane booms have been common in the
art of material handling units. These telescoping crane booms
generally consist of a plurality of hollow sections which are
telescoped relative to each other by hydraulic rams or cables so
that the effective length between the base section attached to a
mobile carrier and the outer end can be varied.
As the overall lifting capacity of these units is increased, it is
also necessary to effectively increase the strength of the boom
with respect to vertical and lateral rigidity. The most ideal type
of boom construction would be to form a boom that is rectangular
and hollow and is integrally formed to provide the desired
rigidity. However, such a boom section construction adds a
substantial amount of overall weight to the entire boom.
It will be appreciated that in large multisection crane booms, the
overall weight of the boom has a direct bearing on the lifting
capacity of the crane. For example, each pound of weight added to
the cantilevered boom will decrease the amount of lifting capacity
for the crane. Thus, manufacturers are constantly striving to
decrease the overall weight of the boom without sacrificing
vertical and lateral rigidity.
SUMMARY OF THE INVENTION
The present invention provides a boom design with a high
strength-to-weight ratio. The elements forming the boom are
rigidified in such a manner that the overall weight of the boom can
be substantially reduced without sacrificing lifting capacity.
More specifically, the boom construction of the present invention
consists of a pair of elongated channel members that each have a
central web portion and a pair of flanges extending substantially
perpendicular at opposite edges of the web portions. The channel
members are positioned so that the web portions are located in
spaced parallel relation to each other and extend substantially
vertically with respect to the boom. The respective pair of
adjacent flanges of the two channel members are interconnected by
plates which define the upper and lower horizontal portions of the
substantially rectangular hollow boom. The hollow rectangular boom
is reinforced at each of the corners thereof by four elongated
angle irons that have their bases located at the respective corners
of the rectangular boom and have legs extending from the corners
thereof along the respective flanges and webs of the channel
members.
The webs of the respective channel members are reinforced between
opposite edges thereof in a manner to produce a high strength web
portion that has a high strength-to-weight ratio. More
specifically, the reinforcing means consists of generally
transversely extending stiffeners which provide vertical and
lateral rigidity to the boom section.
In one version of the invention, the web stiffeners consist of a
plurality of longitudinally spaced stiffener elements for each web
portion of the elongated channel members. Each stiffener element
includes a central core having a plurality of arms extending
therefrom and integral therewith. The central core is located
generally along the center line between the pair of flanges that
extend from opposite edges of the web portion of the elongated
channel and, in the specific embodiment illustrated, the stiffener
elements are X-shaped with the respective pairs of arms extending
in opposite directions and terminating adjacent the flanges of each
web portion. The web portions are further rigidified by
substantially circular buttons which have a circumferential
dimension greater than that of the central cores for the respective
stiffening elements and these buttons are aligned with the central
cores and connected to the web portions of the respective elongated
channels.
To substantially reduce the overall weight of the boom sections
without sacrificing overall strength, the web portions have cutouts
that are substantially diamond shaped and extend generally parallel
to the adjacent edges of the arms of adjacent pairs of web
stiffeners. The result is that the overall structure for the boom
sections will substantially decrease the weight of the unit without
sacrificing lateral or vertical stability of the unit. This will
substantially increase the load capacity that can be lifted with a
crane that has a plurality of boom sections.
In one version of the invention, the web stiffeners consist of a
plurality of longitudinally spaced reinforcing channel bars that
extend substantially vertically or perpendicular with respect to
the longitudinal axis of the elongated channel members and the
channel bars each have a pair of legs extending from a web portion
thereof with the free ends of the legs being connected to the webs
of the channel members.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
FIG. 1 shows a transport vehicle having a multi-section crane boom
supported thereon;
FIG. 2 shows a plan view of one of the outer telescopic boom
sections;
FIG. 3 shows a vertical section of the boom section shown in FIG.
2, as viewed along line 3--3 of FIG. 2;
FIG. 4 is a transverse section of the boom section shown in FIG. 3,
as viewed along line 4--4 of FIG. 3;
FIG. 5 is an exploded fragmentary perspective view of a portion of
the boom section shown in FIG. 2;
FIG. 6 is an enlarged fragmentary view of the base section of the
boom shown in FIG. 1;
FIG. 7 is a transverse section of the boom shown in FIG. 6, as
viewed along lines 7--7 of FIG. 6; and
FIG. 8 is a horizontal section, as viewed along line 8--8 of FIG.
6.
DETAILED DESCRIPTION
While this invention is susceptible of embodiment in many different
forms, there is shown in the drawings and will herein be described
in detail preferred embodiments of the invention with the
understanding that the present disclosure is to be considered as an
exemplification of the principles of the invention and is not
intended to limit the invention to the embodiments illustrated.
Referring to the drawings, particularly FIG. 1, there is shown a
vehicle 10 having turntable 12 rotatable thereon with boom 14
supported on turntable 12 by horizontal pin 16. Boom 14 is pivoted
about pin 16 through fluid ram 18, which is interposed between
turntable 12 and boom 14.
Boom 14 consists of a plurality of sections including a base
section 20 and a plurality of additional outer sections 22 that are
telescoped relative to each other and all outer sections are
capable of being retracted into the outer open end of base section
20. The telescoping movement may be accomplished through any
suitable means, such as fluid rams (not shown).
The outer boom sections 22 are all substantially identical in
construction, except for size, and thus only a single section will
be described in detail with the understanding that the remaining
sections incorporate the same elements in the same relation. FIGS.
2 through 5 show the details of boom section 22.
Boom section 22 consists of a pair of elongated channel members 24
each of which has web portion 26 and a pair of flanges 28 extending
from opposite edges of elongated web portion 26. The two elongated
channel members are positioned so that the web portions are in
spaced, parallel vertical planes and the flanges of the respective
channel members extend towards each other, as shown in FIG. 4. The
free edges of adjacent flanges of the respective channel members
are spaced from each other and are interconnected by a pair of
interconnecting members or plates 30 and plates 30 are preferably
welded to flanges 28.
Thus, the plates 30 and channels 24 define a generally hollow
rectangular box-like structure in cross-section having a plurality
of flat walls. Each of the corners of the hollow rectangular
box-like structure is reinforced by reinforcing plates which are
located adjacent the intersection between flanges 28 and web
portions 26. The pairs of reinforcing plates for each of the
corners consists of angle iron 32 which has a pair of legs 34 that
respectively extend along flanges 28 and web portions 26 and are
secured thereto, as by welding.
The purpose of the reinforcing plates, defined by legs 34, is to
add the most efficient mass as far from the neutral axis as
possible so as to achieve the greatest possible stiffness for the
box-like boom structure. An additional advantage is that angle
irons 32 transmit the vertical compressive reaction forces into the
web portions 26 to increase the distortion strength thereby greatly
decreasing the potential of lateral distortion of the boom section.
A further advantage of the angle irons 32 is to provide a fixed
corner support at each corner of the boom section, which increases
the resistance to buckling stresses that may be developed in the
web portions 26.
Another advantage of the location and size of the angle irons 32 is
that they may also act as wear plates between adjacent portions of
two adjacent boom sections. An inspection of FIG. 4 shows that the
thickness of interconnecting plates 30 is slightly less than the
thickness of the angle iron legs 34 so that the surfaces of legs 34
extend above the outer surfaces of plates 30.
The elongated boom section 22 also has web stiffeners connected to
each web portion for increasing the buckling resistance of the web
portion when weight is supported by the boom 14. The web stiffeners
for boom section 22 consist of a plurality of stiffener elements 40
which are longitudinally spaced along web portion 26. Each
stiffening element 40 has a central core 42 and four arms 44
extending in different directions from central core 42 towards the
respective flanges 28 of the associated channel member 24.
In the illustrated embodiment, legs 44 and central core 42 define a
generally X-shaped stiffener element, in plan view, with the
centers of cores 42 located generally along center line CL of the
elongated channel, center line CL being located between flanges 28
and spaced an equal distance therefrom, as shown in FIG. 3. The
pairs of aligned arms 44 have a combined vertical height which is
substantially equal to the dimension between opposite edges of web
portion 26 and the arms extend diagonally, as viewed from the
inside of the box structure defining boom section 22. The stiffener
elements are located inside the box section and are secured
directly to web portions 26, as by welding.
To decrease the overall weight of boom section 22, without
sacrificing strength, diamond-shaped openings 50 may be cut from
the boundaries defined by an adjacent pair of web stiffener
elements. The net effect is that the material cut from the web
portions 26 substantially decreases the overall weight of the boom
section. This will create a semi-closed lattice boom construction
as shown in FIG. 3.
The web stiffener elements increase the buckling strength of the
edges of openings 50 and provide substantial resistance to bending
and vertical buckling of the web portion which might result from
local compressive reaction forces. If further resistance to
buckling is required, buttons 52 may be positioned to overlie the
respective central cores 42 and be secured directly to the web
portions. These buttons have a dimension that is slightly greater
than the dimension of the central core 42 and may be secured
directly to web portions 26 by welding.
The respective web stiffeners including stiffener elements 40 and
stiffener buttons 52 provide increased vertical buckling strength
for the web and permit greater shear transfer for the web portion
without adding a substantial amount of weight to the overall boom
section. In fact, the amounts of material removed from the web
portions to define openings 50 is greater than the weight of the
web stiffeners added to the boom. The effect is that the overall
weight of the boom section is decreased while the strength thereof
is increased.
Another type of boom section is shown in FIGS. 6 through 8 and this
boom section is particularly adapted to use as the base section 20
which is attached to the turntable. Base section 20 is in many
respects similar to each of boom sections 22 and differs primarily
in the reinforcement for the web portions of the channel
members.
As shown in FIGS. 6-8, boom section 20 again consists of a pair of
elongated channel members 60 each having a web portion 62 and
flanges 64 extending from opposite edges of the web portion.
Channel members 60 are positioned so that web portions 62 extend
parallel to each other and are horizontally spaced by a distance so
that the free edges of adjacent flanges 64 are spaced from each
other. Flanges 64 are interconnected by a pair of interconnecting
members 66, which may be secured thereto, by welding.
Each corner of each channel member is reinforced by an angle iron
68 with two legs 70 of angle iron 68 defining reinforcing plates or
bars extending from each corner of the box-like structure along a
portion of web portions 62 and a portion of flanges 64. Again,
angle irons 68 produce the most efficient mass as far as possible
from the center neutral axis of the box-like structure defining
boom section 20. This will achieve the greatest possible stiffness
with a minimum amount of weight.
Each of the web portions 62 is again reinforced by web stiffeners
71 and in boom section 20, web stiffeners 71 consist of elongated
reinforcing channel bars, each of which has a web 72 and a pair of
legs 74 extending from the web. The free edges of legs 74 are
secured directly to the web portions 62 of channel member 60 to
provide the desired reinforcement. The longitudinal spacing of the
web stiffeners 71 is a function of the overall length of the boom
section, as well as the shear stress in the web.
As in the previous embodiment, bars or plates 70 at the respective
corners of the box-like structure and web stiffeners 71 will
substantially increase the transfer of vertical compressive
reaction forces directly into web portions 62 to produce a greater
resistance to buckling stresses that may be developed on web
portions 62. Again, as in the previous embodiment, the web
stiffeners are designed so as to produce a minimum amount of weight
with a maximum amount of resistance to local compressive reaction
forces and buckling stresses that may be developed in the boom
section. Since this boom section is specifically designed for use
as the base section, the overall weight of the boom section is not
quite as critical as the weight of the remaining telescoping boom
sections 22, and thus there is no need for producing cutouts in web
portions.
To further rigidify the base end of boom section and provide
increased resistance to react against compressive forces along the
lower portions of base section 20, additional longitudinally
extending reinforcing channel bars 80 which are positioned between
adjacent pairs of vertical channel bars 71. These channel bars have
a first leg 82 secured to web portion 62 and a second leg 84
connected to angle iron 68.
As can be appreciated from the above description, the present
invention provides an improved boom construction which produces
greatest resistance to buckling stresses of the vertical portions
of the boom with a minimum amount of overall weight.
* * * * *