Note: Descriptions are shown in the official language in which they were submitted.
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IMPROVED REPLACEABLE MACHINE PART RETENTION SYSTEM
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to replaceable machine parts that are
exposed to high wear and repeated shock loading, such as teeth used
on dragline buckets. Specifically, the system of this invention
comprises a new and improved retention system permitting easier and
quicker changeovers of high-wear replaceable parts.
Description of the Prior Art
Digging and levelling apparatus such as draglines, backhoes,
front-end loaders and like often use replaceable tooth assemblies
which are mounted on the tooth horns to provide sacrificial parts
that are exposed to the repeated shock loading and high wear
occasioned by the digging operation. In such systems, each tooth
assembly typically includes a wedge-shaped adapter which mounts
directly on the tooth horn of the bucket, shovel or alternative
digging or scraping mechanism of the equipment. A wedge-shaped
tooth point is frontally seated on and rigidly pinned to the
adapter for engaging the material to be excavated.
Attachment of the tooth point is typically accomplished by
means of one or more inserts which are inserted into insert
cavities in an adapter. The inserts are internally tnreaaea zc
accommodate a bolt that secures the tooth to the adapter.
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Installation and removal of teeth secured using such a system
requires substantial time and effort, since the tooth point bolts
must be screwed in and unscrewed when the tooth is to be replaced,
operations which requires using a powered impact wrench. Moreover,
the use of such a tool presents the danger of over-torquing,
resulting in damage to the threads and possible personal injury to
the operator.
- SUMMARY OF THE INVENTION
I have discovered that by using a pin featuring spring-loaded _
balls along the shank instead of a threaded bolt, along with an
insert having one or more internal grooves to accommodate the
spring-loaded balls. A pin including such a mechanism can be
inserted manually, without tools, and removed quickly and easily
using a pair of pliers or a special extraction tool designed to fit
a hook built into the pin.
The invention is particularly suited to accomplish quicker and
easier replacement of teeth used for excavating equipment such as
draglines, bucket wheels, but also is applicable to other types of
equipment having sacrificial parts subject to high wear.
It is an object of this invention, therefore, to provide
quicker changeovers for sacrificial parts of machines, especially
digging equipment.
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It is a further object of this invention to provide an
improved system for attaching replaceable teeth to drag line
buckets and similar equipment.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded view of a preferred embodiment of the
tooth assembly of this invention mounted on a conventional tooth
horn of a bucket or shovel of an excavating apparatus;
FIG. 2 is a perspective view of the tooth assembly illustrated
in FIG. 1 assembled on the conventional tooth horn;
FIG. 3 is an exploded view of the adapter and tooth point
elements of the tooth assembly illustrated in FIGS. 1 and 2 in a
second preferred embodiment;
FIG. 4 is a perspective view of an insert element of the tooth
assembly illustrated in FIGS. 1-3;
FIG. 5 is a partial sectional view of the adapter, tooth point
and insert elements of the tooth assembly in assembled
configuration as illustrated in FIG. 2;
FIG. 6 is a side view of the tooth assembly showing the
locations where specific tolerances are provided according to one
embodiment of my invention;
FIG. 7 is a top view of the tooth assembly also showing the
locations where specific tolerances are provided according to one
embodiment of my invention;
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FIG. 8 is a sectional view of the improved insert and pin using
spring-loaded ball bearings; and
FIG. 9 is a sectional view of an alternate embodiment of the
improved pin utilizing springs.
FIG. 10 is a detail showing one possible arrangement of a bar-
type hook recessed into the head of a retaining pin.
FIG. 11 illustrates an extraction tool that can be used to
remove the improved retaining pin of this invention.
FIG. 12 is a sectional view of a second arrangment of the
improved insert in which the pin is non-rotatable.
DETAILED DESCRIPTION
I will describe the attachment system of my invention with
particular reference to the attachment of replaceable teeth to
excavating equipment such as ciragllne buckets, ana more
particularly to the assembly disclosed in my U.S. Patent No.
5,337,495 (issued August 16, 1994) and in my U.S. Patent
Application No. 09/158339, filed September 21, 1998 (System and
Method for Improving the Service Life of Replaceable Parts Exposed
to Shock Loading), the disclosures of which are incorporated by
reference herein. Those skilled in the art will understand,
however, that my invention also is applicable to other machines
using replaceable parts. Examples of such machines include
downhole drills and related tools, conveyor belt parts, center wear
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shrouds and wing shrouds on dragline buckets, track shoes for
tracked vehicles, machine gun and artillery breech parts and the
like.
Referring to the drawings and to FIGS. 1 and 2 in particular,
the tooth assembly of this invention is generally illustrated by
reference numeral 1 and is mounted on a conventional tooth horn 2
of the bucket or shovel of a conventional excavator (not
illustrated). ghe tooth assembly 1 includes a wedge-shaped adapter
3, fitted with a removable tooth point 15, which has a contact edge
18 and is mounted on the adapter 3 by means of a pair of tooth
point retainer pins 33, each extending through a tooth point
retainer pin opening 14 in the tooth point side wall 17 of the
tooth point 15 and threaded in an insert 41, seated in opposite
sides of the adapter 3. In a preferred embodiment, the tooth
assembly 1 further includes a transversely-mounted top wear cap 22
and bottom wear cap 36, both of which are also bolted to the
adapter 3 by means of side plate bolts 32, respectively. In a most
preferred embodiment of the invention the adapter 3 includes a
wedge-shaped adapter base 4 which tapers from a base plate 4a to a
nose ridge 12, terminating the adapter nose 11. A base plate lock
opening 5 is provided in the base plate 4a of the adapter base 4
for receiving a spool 38 and a companion wedge 39 and mounting the
adapter 3 on the tooth horn 2 in conventional fashion. A pair of
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transverse, vertically-oriented, spaced stabilizing slots 6 are
provided in the sides of the adapter base 4, for purposes which
will be hereinafter further described. Spaced, parallel top rib
slots 7 are also provided transversely in the top tapered face of
the base plate 4a of the adapter base 4 and in a most preferred
embodiment, the top rib slots 7 are T-shaped, as illustrated in the
drawings. Similarly, a pair of spaced, T-shaped bottom rib slots 8
are provided iri the bottom tapered surface or face of the adapter
base plate 4a in the same relative position as the top rib slots 7. _
It is understood that the top rib slots 7 and bottom rib slots 8
may alternatively be shaped in a "dove-tail", or alternative
locking configuration, according to the knowledge of those skilled
in the art.
As further illustrated in FIG. 1, the top wear cap 22 and
bottom wear cap 36 are designed to slidably mount transversely on
the adapter base 4 of the adapter 3. The L-shaped top wear cap 22
and bottom wear cap 36 are each characterized by identical cap
plates 23 and corresponding side plates 26 and are therefore
interchangeable. The cap plate 23 of the top wear cap 22 further
includes a cap plate opening 24, which registers with the base
plate lock opening 5 located in the adapter 3, to provide access to
the spool 38 and wedge 39 for readily tensioning the wedge 39 if
necessary, as illustrated in FIG. 1. A pair of spaced, T-shaped cap
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plate ribs 25 are transversely located in the bottom surface of the
cap plate 23 of the top wear cap 22 and are designed to register
with the spaced top rib slots 7 provided in the adapter.3.
Similarly, additional cap plate ribs 25 are provided in spaced
relationship in the top surface of the cap plate 23 of the bottom
wear cap 36 for registering with corresponding spaced parallel
bottom rib slots 8, located in the bottom face of the adapter 3,
also as illustrated in FIG. 1. A side plate retainer pin opening 30
is provided in each of the side plates 26 of the top wear cap 22
and the bottom wear cap 36 for receiving the side plate bolts 32,
respectively, in order to lock the top wear cap 22 on the top and
one side of the adapter 3 and the bottom wear cap 36 on the bottom
and opposite side of the adapter 3, as illustrated in FIG. 2. As
further illustrated in FIGS. 1 and 2 of the drawings, the adapter
3 is fitted with an adapter recess 10 on one side to facilitate
recessing of the side plate 26 of the bottom wear cap 36 and
extension of the corresponding cap plate ribs 25, located in the
bottom surface of the cap plate 23 of the top wear cap 22, into the
corresponding side plate slots 28, provided in the extending end of
the side plate 26 of the bottom wear cap 36. Similarly, the
projecting cap plate ribs 25, located in the cap plate 23 of the
bottom wear cap 36, project in registration with the corresponding
side plate slots 28, located in the extending end of the side plate
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26 of the top wear cap 22 when the top wear cap 22 and bottom wear
cap 36 are assembled and interlocked on the adapter 3, as
illustrated in FIG. 3. A side plate recess 29 is provided in the
side plate 26 of each of the top wear cap 22 and bottom wear cap 36
and surrounds a corresponding side plate retainer pin opening 30,
to accommodate the head of the side plate bolts 32 in countersunk,
recessed relationship. Furthermore, spaced side plate lugs 31 are
provided in the side plate 26 of the top wear cap 22 and bottom
wear cap 36 for registering with the corresponding spaced .
stabilizing slots 6, located in the sides of the adapter 3,
respectively. Accordingly, it will be appreciated by those skilled
in the art that when the top wear cap 22 and bottom wear cap 36 are
mounted on the adapter 3 from opposite sides, with the respective
cap plate ribs 25 engaging corresponding top rib slots 7 and bottom
rib slots 8 located in the bevelled top and bottom faces of the
adapter base 4a, respectively, the top wear cap 22 and bottom wear
cap 36 are interlocked as illustrated in FIGS. 1 and 2.
Furthermore, insertion of the side plate bolts 32 through the
respective side plate retainer pin openings 30 in the side plates
26 of the top wear cap 22 and bottom wear cap 36, respectively, and
threading of the side plate belts 32 in the respective threaded
openings 13 located in the sides of the adapter 3, locks the top
wear cap 22 and bottom wear cap 36 securely on the adapter 3, with
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the side plate lugs 31 engaging the corresponding stabilizing slots
6 located in the adapter 3. The top wear cap 22 and bottom wear cap
36 are thus prevented from disengaging the adapter 3 without
removing the side plate bolts 32. Moreover, the heads of the side
plate bolts 32 are securely recessed inside the respective side
plate recesses 29, provided in the side plates 26, to minimize the
possibility of shearing the side plates retainer pins 32 from the
tooth assembly 1.
In another preferred embodiment of the invention each of the
side plate bolts 32 is provided with a retainer pin shoulder 32a
located beneath the head thereof. However, in a most preferred
embodiment of the invention the heads of the respective side plate
bolts 32 are spaced from the recess shoulder 29a of each side plate
recess 29. This spacing facilitates limited movement of the top
wear cap 22 and bottom wear cap 36 with respect to the adapter 3 as
described in my U.S. Pat. No. 5,172,501 and serves as a
stress-relieving function to minimize damage to the tooth assembly
1 by operation of the excavation or levelling equipment upon which
the tooth assembly 1 is mounted.
Referring now to FIGS. 1 and 3-5 of the drawings, the tooth
point 15 is removably attached to the adapter 3 by means of two
tapered inserts 41, each inserted in a correspondingly-shaped
insert cavity 47, provided in the wedge-shaped tooth point side
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walls 17 of the adapter 3. Each insert 41 includes an insert bore
45, extending through a tapered, rounded insert body 44 which
terminates in an insert shoulder 42, having a straight shoulder
edge 43. The respective oppositely-disposed insert cavities 47 are
tapered and shaped to define a cavity shoulder 48, which engages
the insert shoulder 42, and a body curvature 49, which engages the
insert body 44. Accordingly, the insert cavities 47 removably
receive the inserts 41 and prevent the inserts 41 from rotating
when pressure is applied to the tooth point retainer pins 33, which
secure the tooth point 15 on the adapter 3. When the preferred
retainer pins of Figures 8 and 9 are used, lockwasher 35 is
preferably omitted. Optionally, when the retainer pins of Figures
8 and 9 are used, the insert 41 may not require an insert shoulder
that is shaped to prevent rotation.
Those skilled in the art will understand that various shapes
can be used for insert 41, such as square, circular, star-shaped
and the like.
Accordingly, referring again to FIGS. 1 and 2, the tooth point
15 is designed to mount frontally on the adapter nose 11 of the
adapter 3 by matching the tooth point retainer pin openings 14,
located in the opposite tooth point side walls 17 of the tooth
point 15, with the corresponding insert bores 45, provided in the
inserts 41. Each tooth point retainer pin 33 is then registered
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with a corresponding tooth point retainer pin opening 14 and the
shank of each tooth point retainer pin 33 is inserted into the
corresponding insert bore 45 located in the insert 41, to removably
secure the tooth point 15 on the adapter 3. When the tooth point
15 is so inserted on the adapter 3, the tooth point edge 15a is
located in close proximity to the corresponding edges of the cap
plates 23 and side plates 26 of the top wear cap 22 and bottom wear
cap 36, respectively, as illustrated in FIG. 2. However, a working
gap 37 is maintained between the tooth point edge 15a of the tooth
point 15 and the front edges of the top wear cap 22 and bottom wear
cap 36, respectively, to facilitate movement of the tooth point 15
and top wear cap 22, as well as the bottom wear cap 36, with
respect to the adapter 3. As illustrated in FIG. 5, since the
diameter of the tooth point retainer pin opening 14 is smaller than
the external dimensions of the inserts 41 at the insert shoulder
42, the inserts 41 cannot exit the respective insert cavities 47
through the tooth point retainer pin openings 14. However, the
inserts 41 can be easily removed from the insert cavities 47 when
the teeth are removed from the adapter 3. Accordingly, the tooth
point 15 is afforded a range of movement on the adapter nose 11 due
to the space between the heads of the tooth point retainer pins 33
and the periphery of the tooth point retainer pin openings 14, as
well as the working gap 37, to relieve digging stresses.
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It will be appreciated from a consideration of the drawings
that the tooth assembly of this invention exhibits multiple
favorable structural characteristics not found in conventional
assemblies. The interlocking relationship between the top wear cap
S 22 and bottom wear cap 36, along with the transverse, slidable
mounting of these structural members and the removable mounting of
the tooth point 15 on the adapter 3, facilitate an extremely
strong, versatile wear-resistant assembly. Furthermore, recessing
of the respective side plate bolts 32 and tooth point retainer pins
33, as well as the side plates 26 of the top wear cap 22 and the
bottom wear cap 36 provided in opposite sides of the adapter 3,
facilitate excavation and levelling of all types of material
without fear of shearing the respective side plate bolts 32 and
tooth point retainer pins 33. Moreover, use and replacement of the
top wear cap 22, bottom wear cap 36 and tooth point 15
independently or in concert, is quickly and easily facilitated in
an optimum manner by simply removing the side plate bolts 32 and
tooth point retainer pins 33, sliding the top wear cap 22, bottom
wear cap 36 and tooth point 15 from the adapter 3 and replacing
these members by reversing this procedure. Shock and impact
resistance of the tooth assembly 1 is facilitated by mounting the
top wear cap 22 and bottom wear cap 36 and tooth point 15 in a
non-rigid, but secure relationship on the adapter 3 to facilitate
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a selected minimum movement of the top wear cap 22, bottom wear cap
36 and tooth point 15 with respect to the adapter 3 during
operation. Use of the inserts 41 to mount the tooth point 15 on
the adapter 3 facilitates quick and easy removal and replacement of
the tooth point 15 without risk of cross-threading a tooth point
bolt directly into tapped holes provided in the adapter 3. Such
tapped holes are subject to various types of damage and the inserts
41 are capable of easy replacement to avoid this problem. A tooth
assembly 1 is mounted on each tooth horn 2 of a conventional bucket _
or shovel of a conventional excavating apparatus in conventional
manner, utilizing the spool 38 and wedge 39, according to the
knowledge of those skilled in the art. It will be appreciated that
alternative means for mounting the tooth assembly 1 to the tooth
horn of such equipment may also be implemented without departing
from the spirit and scope of the invention as embodied herein.
FIG. 6 and FIG. 7 illustrate the specific tolerances of my
invention. FIG. 6 shows a preferred embodiment of my invention as
applied to a replaceable tooth point 15 for a dragline bucket. In
the side view of FIG. 6, the removable tooth point 15 is shown
attached to the wedge-shaped adapter 3, held loosely in place by
insert 41. The approximate direction of the heaviest shock load
is shown at reference numeral 100. As shown in the following
examples, I have found that providing the following clearances
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between the sacrificial part (the removable tooth point 15, in this
example) and the adapter 3 upon which it is mounted will
effectively and surprisingly increase the life of the sacrificial
part:
S ~ Horizontal clearance at reference numeral 101 in approximate
direction of shock: about 1/8 inch to about 1/4 inch.
~ Vertical clearance at reference numeral 102 normal to
approximate direction of shock: about 1/32 inch to about 3/16
inch; preferably about 1/16 inch to about 1/8 inch.
~ Horizontal clearance at reference numeral 103 normal to
approximate direction of shock: about 1/32 inch to about 1/16
inch.
I find that if larger clearances are used the teeth will tend to
move forward and contact the bolts, causing failure by bending or
fracture; whereas if smaller clearances are used there will be
interference from the castings, notably between the adapter 3 and
the sacrificial part 15.
Figure 8 illustrates a preferred embodiment of my invention in
which the tooth point retainer pin 202 is not threaded, but instead
is fitted with a cavity 205 containing at least one spring-loaded
ball bearing 203 and a spring mechanism 204 which urges the ball
bearing 203 radially outwardly as far as permitted by the hole 206
in the shank of the insert pin 202. The corresponding insert 20C
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includes an internal slot or depression 201 suitable for
accommodating the one or more ball bearings 203. When the retainer
pin 202 is inserted into the cavity of the insert 200, the ball
bearings 206 retract until they reach the internal slot 201, at
which point the spring mechanism 206 forces the ball bearings 203
radially outward into the slot 201, securing the retainer pin 202
in the insert 200. This operation preferably is accomplished
manually without need for tools. To remove the retainer pin 202,
a pair of pliers may be used, or if the retainer pin 202 is
designed to be flush or recessed, an extractor tool (not shown)
suitable for engaging a hook 207 on retainer pin 202 may be used to
remove the retainer pin 202. Preferably, hook 207 is arranged as
shown in Figure 10, with the hook formed as a bar recessed in a
cavity 226 in the head of the retaining pin to protect it from dirt
and wear. Figure 11 shows an extraction tool 220 comprising a
shaft 223 on which a sliding weight 221 moves longitudinally. The
distal end of the shaft includes a recess 224 suitable for engaging
the hook or bar 207 that is recessed into the retaining pin shown
in Figure 10. A stop 222 near the proximal end of the extraction
tool permits the sliding weight to act as a slide hammer to
dislodge retaining pin 202. Optionally, the proximal end 225 of
the extraction tool can be pointed so that it can be used to clean
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out the cavity 226 before engaging the bar 207 with the recess 224
near the distal end of the shaft of the extraction tool.
In any event, tooth retention is achieved without need for
threading and unthreading a bolt.
Figure 9 illustrates an alternative embodiment, in which
instead of ball bearings, one or more springs 213 set into cavities
214 are used to retain the retainer pin 212 in the insert 210 by
engaging slots-211.
Figure 12 illustrates another preferred embodiment of my _
invention in which the tooth point retainer pin 226 is not
threaded, but instead is fitted with one or more cavities 227a and
227b containing at least one spring-loaded ball bearing or pin and
a spring mechanism which urges the ball bearing or pin radially
outwardly as far as permitted by the hole 227a or 227b in the shank
of the insert pin 202. The corresponding insert 228 includes one
or more internal depressions 229 suitable for accommodating the one
or more ball bearings or pins 203. When the retainer pin 226 is
inserted into the cavity of the insert 228, the ball bearings or
pins retract until they reach the internal depressions 229, at
which point the spring mechanism forces the ball bearings or pins
radially outward into the depressions 229a or 229b, securing the
retainer pin 226 in the insert 228. In addition, it has been found
that it is desirable to prevent rotation of the retainer pin 226 in
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the insert 228 because during use, if the retainer pin rotates, it
may cause the ball bearings or pins to work back into their slots,
permitting the retainer pln to come =ree o~ ~c~e l~mCL ~ .
Accordingly, the embodiment of Figure 12 includes a non-rotation
device 230, which preferably may comprise a cap 230 with a
transversely-extending ridge 231 that mates with a transversely-
extending slot 232 in the base of the retainer pin 226 when the
retainer pin 2Z6 is fully seated in the insert 228. It will be
recognized that other arrangements of non-rotation devices are
possible, so long as the goal of preventing rotation of the
retainer pin relative to the insert is accomplished.
It will be understood that the arrangements of springs or ball
bearings and slots illustrated in Figures 9, 10 and 12 can be
reversed if desired, so that the spring or springs are placed in
the adapter and the mating slot is in the retainer pin.
In addition, the insert can be eliminated altogether by
machining an aperture and slot directly into the adapter nose 11 in
the insert cavity 49.
EXAMPLES
In a test comparing dragline bucket teeth attached to a 90
cubit yard dragline bucket according to my invention with
,
conventional, rigidly-attached dragline bucket teeth, the teeth
attached according to my invention exhibited an average life of
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approximately 161 hours compared to 79 hours for the
conventionally-attached teeth. The adapter used with the non-rigid
attachment system of my invention exhibited an average life of
approximately 1655 hours compared to 1113 hours for the adapter
using conventional, rigid attachment to the teeth.
In another test at a Phelps-Dodge mine, the rate of tooth wear
using my non-rigid attachment system on a dragline bucket was
approximately x.75 inches per 24 hour period, approximately half
the rate of wear for conventional, rigid attachment of the teeth.
Those skilled in the art will appreciate that increasing the
life of the sacrificial parts not only saves money for replacement
parts themselves, but also reduces maintenance downtime and labor
costs for parts replacement.
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