APPAREIL ET PROCEDE AMELIORES D'APPLICATION D'UN REVETEMENT ANTI-USURE

IMPROVED APPARATUS AND METHOD FOR APPLYING A WEAR COATING

Abrégé français

Il est décrit un procédé et un appareil dapplication dun revêtement anti-usure au côté carrière dune pièce dusure. Linvention concerne une pièce dusure améliorée avec un revêtement résistant à lusure.

Abrégé anglais

A method and apparatus for applying a wear coating to the back side of a wear
part is provided.
The invention is directed to an improved wear part with a wear resistant
coating.

Revendications

The invention claimed is:
1. A ground engagement wear part comprising a front face and a back face
opposite thereto,
wherein a wear resistant coating is welded to the back face and the front face
is uncoated.
2. The wear part of claim 1 where the wear resistant coating is tungsten
carbide coating.
3. An engagement tool comprising a leading face and a back face, wherein
only the back
face is coated with a substantial thickness of wear resistant coating.
4. A method of coating a wear part with a wear resistant comprising coating
only the back
face of a wear part with a wear resistant coating.
5. The wear part of claim 1 wherein the wear resistant coating is confined
to the bottom of
the back face adjacent to the front face.
6. The wear part of claim 1 wherein the wear coating has a substantial
thickness.
7. The wear part of claim 1 wherein the wear coating is applied without an
annealing step.
8. The wear part of claim 1 wherein the wear coating extends the life of
the front face by
protecting the back face from wear.
9. The wear part of claim 1 wherein the wear coating does not interfere
with the flow of
material over the front face of the wear part.
10. The wear part of claim 1 wherein the application of the wear coating
does not
substantially change the ductility of the front face.
11. The wear part of claim 1 wherein the wear part is a ripper.
12. The wear part of claim 1 wherein the wear part is a sweep.
13. The wear part of claim 1 having an edge between the front and back
faces, and said wear
coating extends from the back face onto the edge.
14. A ground engagement wear part comprising a forward face and a leeward
face opposite
thereto, wherein a wear resistant coating is welded to the leeward face and
the forward face is
uncoated with wear resistant coating.
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Description

IMPROVED APPARATUS AND METHOD FOR APPLYING A WEAR COATING
RELATED APPLICATIONS
The present application claims priority to United States Provisional Patent
Application No. 61/538,451 filed on September 23, 2012.
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
This invention relates to an apparatus and method for applying a wear coating
to the
back side of a wear part.
BACKGROUND
Wear parts such ground engagement tools used in agricultural applications such
as
plow sweeps and rippers, as well as other wear parts, are subject to extreme
wear and tear.
These parts are as a result frequently replaced as they deteriorate to the
point where they are
no longer effect at the intended task. This occurs because the leading face,
which does the
bulk of the work, becomes dull from abrasion and wears away dramatically
limiting the
effectiveness of the part.
The part then requires replacement, which involves expense and down time. The
problems of wear and replacement have been somewhat ameliorated by the use of
wear
resistance coatings placed on the working face of the wear parts. These
coatings are very
dense and resistant to abrasion. Tungsten carbide is a common wear resistant
coating used
for extending the life of such wear parts.
In the prior art, the leading face (the face that undergoes the most wear) is
coated
with a wear resistant coating. This will extend the life of the tool, but it
has the drawback of
making it a less effective cutting tool. Wear resistant coatings, such as
tungsten carbide, are
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very dense and thick. As a result, they interfere with the flow of the
material over the leading
face of the wear part. Also, they dull the leading face reducing the cutting,
or tearing, effect
of the face.
In some prior art applications, the both the leading and back side face of the
wear part
are coated with a wear resistant coating. There is no disclosed advantage of
coating both
sides, and such parts suffer from the same disadvantages as parts with
coatings on the leading
face. Thus, coating both sides appears to do nothing to enhance the tools but
is a waste of
wear coating.
Accordingly, a need exists for a wear coating that will extend the life of a
wear part
.. but not interfere with the effective use of the tool.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a wear part with a wear
resistant
coating that substantially eliminates the problems of the prior art.
These and other objects of the present invention will become apparent to those
skilled
in the art upon reference to the following specification, drawings, and
claims. To that end,
the present invention comprises a wear part with a leading face and a back
face, wherein the
back face is coated with wear resistant coating.
BRIEF DESCRIPTION OF DRAWINGS
Figure I a shows back face of a plow sweep.
Figure lb shows the leading (front) face of the plow sweep.
Figure 2 shows various hammer tips.
Figure 3 shows the back face of a standard ripper and a ripper with wear
coating.
Figure 4 is a flow chart of a welding process.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention involves the addition of Tungsten Carbide chips to the
molten
puddle of a MIG weld. A fine to coarse grit carbide can be used for different
applications. It
is preferred that the weld puddle be as fluid as possible for best results.
This restricts the
welding to a horizontal plane only. The part being welded must be flat and
level, or a
positioner can also be incorporated. A robot can move a part under a
stationary MIG gun and
carbide feeder, instead of moving the welding head. This will allow
application of the weld
efficiently to a curved or multi faceted part with minimal handling. This is
also important in
applying the weld in a manner that best protects the high wear areas. By
concentrating on the
initial points of wear, the life of the parts is extended with a minimal
amount of weld. This
invention is particularly applicable to "ground engagement" tools such as
rippers and sweeps,
specifically in the agriculture market. Previously, hard face welding in many
forms has been
used in these fields with only moderate success. The invention is more broadly
applicable to
general wear parts such as hammers and hammer tips of the type used with
rotary
hammerinills in tub grinders, and wear parts used in construction, mining,
screening,
conveying, crushing, plowing, road maintenance, and grader applications. These
can include
for example cutting faces, teeth, adapters, jaws, wedges, blades, and the
like.
In prior art applications, the wear surface has been applied to the face of
the tool (the
side in full contact with the soil). In the present invention, application of
a narrow weld to
the back side of the leading face of these various tools achieves a much
longer tool life than
the prior art, and at a minimal cost. The present invention utilizes multiple
stationary
welding stations with the ability to apply both coarse and fine grit carbide
welds to the same
part without handling the part twice, and without changing anything with a
welder.
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Figure la shows the backside weld of the present invention applied to the
backside of
a plow sweep blade, comprised of tungsten carbide. Figure lb shows the reverse
(leading)
side of the plow sweep blade, which is not coated with any wear coating.
Figure 2 shows the
backside of various wear parts with the weld applied. The wear parts are of
the type used
with a rotary hammermill of a tub grinder or the like. Figure 3 shows the back
face of a
standard ripper blade and one with wear coating of the present invention.
Placing the wear coating on the back, non-impact surface, of the wear part
produces
surprising advantages. The presence of the wear coating on the backside
supports the impact
front side surface and better prevents wear than coating the front side. This
is counter
intuitive, and the prior art teaches away from such an approach. Additionally,
in those
situation where the sharpness of the face matters, coating the back side
preserves a sharp
cutting face. Coating the front side with a substance such as tungsten carbide
defeats this
advantage due to the fact that carbide coatings dull the face. Still further,
the wear coating
lasts longer since it is not in the path of abrasion as it would be with front
side coating. Also,
coating the back side reduces the amount of wear coating that needs to be
applied in those
cases where coating is applied to both sides of a wear part.
The welding cell welders of the present invention, because they are now
stationary
will be different and much more sophisticated as the speed and the heat levels
and makeup of
the matrix of weld and carbide mix can all be programmed to work in parallel
with the robots
programs.
Prior art welds are hard facing such that the abrasion wear is always put on
the face
of the working part that makes contact with soils or other contact surface,
such as for digging,
grind materials, or soil contacts. In many prior art applications, the solid
carbide can only be
applied to a flat and prepared surface, and the surface tends to shatter on
impact with foreign
objects, rocks and any abrasive material trying to be stirred, moved or
conveyed..
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By using a granule or other carbide weld matrix on the backside of the face to
be
protected the working face is actually reinforced, and made stronger. The weld
does not
allow the face to prematurely wear off, and does not diminish the flow of the
material to be
moved. As the part finally starts to wear, the weld does not wear and this
tends to sharpen
the face as the wear is forced to occur on front face or top.
Another advantage of the present invention comes from the fact that the
welding
process does not weaken or soften the forward working face of the wear part
with our
process. Studies have shown on typical hard surface coating that once a wear
coating erodes
the base material will then wear at an accelerated rate because it was
softened in the weld
process. The present invention solves this problem.
Studies have also shown that because the weld will not delaminate on impact
and will
only crack when the base material fails. This is not the case with the prior
art welds. The
weld of the present invention actually becomes part of the base material, thus
creating a very
durable face that almost cannot be removed with 4 to 10 times the wear of
standard material.
The welding cell, shown in the flow diagram below, used to apply the welds of
the
present invention has the following properties:
1. It is computer-controlled robotics, with infinite variations for
programming
applications to many different parts of literally any wear surface that needs
to be sustained in
abrasion situations.
2. The present welding machine makes one pass at a described width and speed
and
then the jig is rotated by the operator holding the parts (usually six to ten
parts at a time) and
die welder makes another pass. Prior art welders and carbide applicators move
on a linear
line and weave the weld on the parts that are held in line side by side. The
prior art welders
must make four complete passes, and are manually rotated by the operator,
until the top and
front of each part has been covered. The operator then removes the parts from
the jig,
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manually breaks them apart since the weld is continuous and holds the parts
together. Then
the parts move to a manual station where an operator manually applies welds to
the corners
and sides as needed by the customer. The manual welding is done one at a time
and the
welder, wire and carbide float above the part as the operator directs where
the weld is to be
put. In the present invention, the welder, wire and carbide applicator are all
stationary.
2. A robot works on two - 90 degree arcs.
3. The robot has two stations each working within a 90-degree arc actually
creating
two stations with one robot. While the robot is working on one 90 section, the
operator can
be setting up the robot for the next part to be welded. Thus, eliminating the
down time
between setups.
4. The welding station could even be set up with as many different carbide
matrixes
welders as desired to apply multiple coatings to the same part. For example, a
first weld with
one carbide mixtures and configuration of widths, and then a second weld and
applicator at
the same station with a different programmed width, size, and mixture.
5. The robot can be rotated to its other 90 degree arc two station set up
position, and
it begins work immediately while the operate loads the non working welding
system.
6. By using this system, where the part is moved and completed in one pass,
standard
parts can be welded in one pass. This can be applied to any type of part,
where the only
change necessary is to change the fixtures used for the particular part, and a
change to the
program. For example, the system can be easily adapted to weld an Ag sweep, a
bucket tooth
hardfacing, or mixer blades for commercial mixers.
While the preferred embodiment of the invention has been described in
reference to
the Figures, the invention is not so limited. The present invention is
adaptable and/or useful
in the following applications and tools, agricultural ground engagement tools,
seed openers
plows points, sweeps, furrowers, knives, shovels, and shanks or any tool that
makes contact
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with soils and that would benefit from preservation or prevention of damage to
the
leading point or face. Also, the present invention is applicable to commercial
mixing
blades, augers, or any application that where it would be helpful to extend
the life of
the leading face such tools and apparatus. Construction applications are also
applicable such as graders, blades, bucket teeth, and compactor teeth. The
invention
is more broadly applicable to general wear parts such as hammers and hammer
tips of
the type used with rotary hammermills in tub grinders, and wear parts used in
construction, mining, screening, conveying, crushing, plowing, road
maintenance,
and grader applications. These can include form example cutting edges, teeth,
adapters, jaws, wedges, blades, and the like.
Unless otherwise defined, all technical and scientific terms used herein have
the
same meaning as commonly understood by one of ordinary skill in the art to
which
this invention belongs. Although methods and materials similar to or
equivalent to
those described herein can be used in the practice or testing of the present
invention,
suitable methods, and materials are described below. In case of conflict, the
present
specification, including definitions, will control.
The present invention may be embodied in other specific forms without
departing
from the spirit or essential attributes thereof, and it is therefore the
desired that the
present embodiment be considered in all respects as illustrative and not
restrictive,
reference being made to the appended claims rather than to the foregoing
description
to indicate the scope of the invention. Those of ordinary skill in the art
that have the
disclosure before them will be able to make modifications and variations
therein
without departing from the scope of the invention.
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