U.S. patent number 3,902,295 [Application Number 05/472,965] was granted by the patent office on 1975-09-02 for boom construction and method for making same.
This patent grant is currently assigned to Caterpillar Tractor Co.. Invention is credited to John W. Yancey.
United States Patent |
3,902,295 |
Yancey |
September 2, 1975 |
Boom construction and method for making same
Abstract
An excavator boom has attachment means formed on opposite ends
thereof for attachment to a vehicle and to a work implement. The
boom comprises a pair of continuous and uninterrupted upper and
lower plates and a pair of side plates, all secured together by
four continuous welds to form a box section throughout the length
of the boom. The boom is generally V-shaped and has a third
attachment means formed at the apex thereof. During fabrication of
the boom, the various plates and attachment means are positioned in
suitably arranged fixtures and are tack welded together. The boom
is then placed on each of its sides for final welding purposes.
Inventors: |
Yancey; John W. (Aurora,
IL) |
Assignee: |
Caterpillar Tractor Co.
(Peoria, IL)
|
Family
ID: |
23877620 |
Appl.
No.: |
05/472,965 |
Filed: |
May 28, 1974 |
Current U.S.
Class: |
37/379; 414/715;
37/443; 414/722 |
Current CPC
Class: |
E02F
3/32 (20130101); E02F 3/38 (20130101) |
Current International
Class: |
E02F
3/38 (20060101); E02F 3/36 (20060101); E02F
3/42 (20060101); E04C 003/30 (); E02F 003/00 () |
Field of
Search: |
;52/730 ;214/145 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Bell; J. Karl
Attorney, Agent or Firm: Phillips, Moore, Weissenberger
Lempio & Strabala
Claims
I claim:
1. A generally V-shaped boom comprising
attachment means on a first end of said boom adapted for attachment
on a vehicle,
a pair of continuous and uninterrupted upper and lower plates and
side plates each extending substantially the full length of said
boom between the first and second ends thereof to form a box
section,
four continuous weld means each securing a lateral side of each one
of said upper and lower plates to a respective one of said side
plates and
second attachment means disposed at an apex of said boom comprising
a pair of annular castings each disposed in an opening formed
through a respective side plate and an intermediate cylindrical
connecting member secured between said castings.
2. The boom of claim 1 wherein said attachment means pivotally
mounts said boom on a frame of an excavator and further comprising
another attachment means on a second, opposite end of said boom
pivotally attached to a work implement.
3. The boom of claim 1 further comprising an L-shaped angle bar
disposed interiorly of said boom and secured to each of said weld
means at an apex thereof, said weld means and a respective angle
bar being co-terminus at least substantially throughout the length
of said boom.
4. The boom of claim 1 wherein each of said side plates comprises
first and second co-planar plates and a weld, disposed transversely
relative to said side plates, securing said first and second plates
together.
5. The boom of claim 4 further comprising a flat back-up member
secured to said weld and abutting said first and second plates,
interiorly of said boom.
6. The boom of claim 4 wherein said first plate has a wall
thickness greater than the thickness of said second plate, an end
portion of said first plate adjacent to said second plate being
tapered-down to substantially match the wall thickness of said
second plate.
7. The boom of claim 1 further comprising an annular first flange
formed on each of said castings to extend radially outwardly
therefrom to abut inner surface portions of a respective side
plate.
8. The boom of claim 7 further comprising an annular weld securing
each of said castings to a respective said plate at said first
flange.
9. The boom of claim 7 further comprising an annular second flange
formed on each of said castings to extend axially inwardly to
underlie a respective end of said connecting member and an annular
weld securing each of said castings to a respective end of said
connecting member at said second flange.
Description
BACKGROUND OF THE INVENTION
Implement carrying booms for hydraulic excavators and the like are
normally fabricated from a plurality of steel plates secured
together by a multiplicity of transverse and longitudinal welds.
The plates are normally roll formed to provide a back-up ridge for
the longitudinal welds (see FIG. 8 of applicant's drawings) which
gives rise to various stress problems discussed in applicant's
copending U.S. application Ser. No. 348,926, filed on Apr. 9, 1973
for "Stress-Relieved Weldment for Box Sections". Stress
concentrations are particularly occasioned at a mid-portion of the
boom whereat cast members are secured thereto to provide attachment
means for one end of a hydraulic cylinder which is further attached
to a vehicle for boom raising and lowering purposes.
SUMMARY OF THIS INVENTION
An object of this invention is to provide a boom construction which
exhibits a high degree of structural integrity and an economical
method for expeditiously making the same. The boom comprises
attachment means formed on opposite ends thereof, a pair of
continuous and uninterrupted upper and lower plates and side plates
secured to the upper and lower plates by four continuous weld means
extending substantially the full length of the boom. The boom is
fabricated by positioning the various plates and attachment means
in suitably arranged gigs and fixtures and by initially tack
welding them together. The boom is then laid on each of its sides
for the final welding operation.
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects of this invention will become apparent from the
following description and accompanying drawings wherein:
FIG. 1 is a side elevational view of a hydraulic excavator
employing a boom of this invention thereon;
FIG. 2 is an enlarged, side elevational view of the boom;
FIG. 3 is an enlarged sectional view taken in the direction of
arrows III--III in FIG. 2;
FIG. 4 is an enlarged sectional view taken in the direction of
arrows IV--IV in FIG. 2;
FIG. 5 is a view similar to FIG. 4 but illustrating a prior art
weldment;
FIG. 6 is an enlarged cross sectional view taken in the direction
of arrows VI-- VI in FIG. 2;
FIG. 7 is a view similar to FIG. 3 but showing attachment structure
exploded with the welds removed therefrom; and
FIG. 8 is an enlarged top plan view of one end of the boom, taken
in the direction of arrows VIII--VIII in FIG. 2.
DETAILED DESCRIPTION
FIG. 1 illustrates a hydraulic excavator 10 having a first end of a
boom 11 of this invention pivotally mounted thereon by a first
pivot means 12. The second end of the boom is attached to a work
implement, such as a bucket 13, by a second pivot means 14 and
intermediate stick 15. The boom is generally V-shaped and has a
pair of first double-acting hydraulic cylinders 16 (one shown) each
attached to an apex thereof by a third pivot means 17.
The head end of the cylinders are each pivotally attached on the
vehicle by a fourth pivot means 18 to facilitate raising or
lowering of the boom under control of the operator. A second
double-acting hydraulic cylinder 19 has its head end mounted on an
upper side of the boom by a fifth pivot means 20 and its rod end is
attached to the upper end of stick 15 by a sixth pivot means 21. A
third double-acting hydraulic cylinder 22 is pivotally
interconnected between an upper end of stick 15 and bucket 13,
through suitable linkage means 23, to selectively pivot the bucket
on the stick.
Referring to FIG. 2, boom 11 comprises a pair of continuous and
uninterrupted upper and lower plates 24 and 25, respectively, and a
pair of side plates 26 secured thereto. The structurally integrated
plates form a box section substantially throughout the full length
of the boom. Each side plate 26 comprises a pair of plates 26 and
27 secured together at a transverse weld 28 (FIG. 3).
The weld is backed-up throughout its length by a flat member 29
disposed interiorly of the boom. The boom's structural integrity is
not adversely affected by such a weld. In particular, the major
stresses imposed on the boom during operation thereof occur
adjacent to its apex, at attachment means 17 (FIG. 1).
As further shown in FIG. 3, each plate 26 may have a thickness
T.sub.1 (e.g., 1 in.) which is greater than the thickness T.sub.2
(e.g., 3/4 in.) of each plate 27. The forward end of each plate 26
is preferably machined to form a taper throughout a forward portion
L of its length to match the thickness of a respective, co-planar
plate 27. Such a construction substantially reduces the overall
weight of the boom without adversely affecting its bending
strength.
Referring to FIG. 4 the upper, lower and side plates are secured
together by four continuous weld means 30, each securing a lateral
side of one of the upper and lower plates to a respective one of
the side plates. As shown, each weld means 30 has a generally
V-shaped cross section terminating at an apex thereof at an
L-shaped angle bar 31 which functions as a back-up means for the
weld. Such a stress relieved weldment is fully disclosed in
applicant's above referenced U.S. application Ser. No. 348,926. In
particular, FIG. 5 illustrates a prior art weldment wherein a pair
of plates 25' and 26' are secured together by a weld 30' which
terminates at its apex at a rolled section 31' formed on plate
25'.
Since the rolled section is formed integrally with the plate, it
cannot be selectively sized or positioned to accommodate
manufacturing and assembly tolerances a and b. As a result, weld
"blow-through" may occur whereby a poor weldment is formed to
adversely affect the overall structural integrity of the boom. In
contrast thereto, angle bar 31 (FIG. 4) can be suitably sized and
positioned to provide a zero clearance between the angle bar and
side plate 26 and a precisely controlled clearance C at the apex or
root of weld 30 to assure the formation of structurally sound
weldments.
Referring to FIGS. 1, 6 and 7, pivot means 17 comprises an
attachment means including a pair of bell castings 32 each
extending through an annular opening 33 formed through a respective
side plate 26 and secured thereto by an annular weld 34. An annular
first flange 35 is formed on each bell casting to extend radially
outwardly therefrom to abut inner surface portions of plate 26 to
precisely position the bell casting thereon and to also provide a
weld back-up means thereat for weld 34. An annular second flange 36
extends axially inwardly from each bell casting to underlie a
respective end of an intermediate cylindrical connecting member 37.
A pair of annular welds 38 secure the opposite ends of the
connecting member to the bell castings.
Referring to FIGS. 1 and 8, first pivot means 12 comprises an
attachment means or yoke at the first end of the boom having a pair
of bearing bushings 39 secured thereon for pivotally mounting the
boom on the frame of vehicle 10. Referring to FIGS. 1 and 2, second
pivot means 14 comprises an attachment means or casting 40 welded
on the second or forward end of the boom for pivotal attachment to
stick 15. As further shown, fifth pivot means 20 comprises an
attachment means or casting 41 secured on upper plate 24 for
pivotally attaching the head end of cylinder 19 thereon.
METHOD OF FABRICATION
Boom 11 is fabricated by first flame cutting and shaping upper,
lower and side plates 24-26. Openings 33 (FIG. 7) are formed
through the side plates and castings 32 and member 37, presecured
together by welds 38, are suitably mounted therein. The vertical
legs of preshaped angle bars 31 are then tack welded to the side
plates in a suitable fixture whereby each leg projects slightly
beyond a lateral end of a side plate to precisely set clearance C
(FIG. 4) for subsequent formation of the weld grooves for welds
30.
Lower plate 25 is then mounted in a suitable fixture, in its FIG. 2
position. The side plates, having castings 32 and member 37 tack
welded thereto, are then accurately positioned on the bottom plate
25 and tack welded thereto. Top plate 24 is then positioned on the
side plates and tack welded thereto along with castings 32 and 41
and bushings 39.
The tack welded sub-assembly is then turned on a first side thereof
to complete the exposed major welds, including a weld 34 and two of
the four continuous welds 30 securing the upper, lower and side
plates together. The boom is then turned over onto its second,
opposite side and a similar welding operation is effected thereon
to complete the major welds. The boom is then mounted on excavator
10 (FIG. 1) and attached to the various cylinders and stick 15.
* * * * *