U.S. patent application number 10/614145 was filed with the patent office on 2004-01-08 for replacable wear surface for bit support.
Invention is credited to Latham, Winchester E..
Application Number | 20040004389 10/614145 |
Document ID | / |
Family ID | 46299565 |
Filed Date | 2004-01-08 |
United States Patent
Application |
20040004389 |
Kind Code |
A1 |
Latham, Winchester E. |
January 8, 2004 |
Replacable wear surface for bit support
Abstract
A cutter assembly includes a cutting bit, a replacable wear
surface in the form of a washer, and a sleeve. The cutting bit has
a forward cutting tip, a rearward extending shank adapted to be
received in a tool holder, and a rearward facing shoulder. The
sleeve surrounds the shank and includes a forward edge. The washer
includes a central hole receiving the cutting bit shank, a front
surface and a back surface joined by an outer asymmetrical edge of
angularly variable radius. A portion of the washer front surface is
in sliding contact with the rearward facing bit shoulder. The
washer back surface includes a lip extending rearward from only a
segment of the asymmetric edge for engaging an outer shoulder of a
holder to inhibit rotation of the washer relative to the
holder.
Inventors: |
Latham, Winchester E.;
(Avon, IN) |
Correspondence
Address: |
BRINKS HOFER GILSON & LIONE
ONE INDIANA SQUARE, SUITE 1600
INDIANAPOLIS
IN
46204-2033
US
|
Family ID: |
46299565 |
Appl. No.: |
10/614145 |
Filed: |
July 7, 2003 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10614145 |
Jul 7, 2003 |
|
|
|
10171939 |
Jun 14, 2002 |
|
|
|
Current U.S.
Class: |
299/104 ;
299/107 |
Current CPC
Class: |
E21C 35/18 20130101 |
Class at
Publication: |
299/104 ;
299/107 |
International
Class: |
E21C 025/10 |
Claims
What is claimed is:
1. A cutter tool comprising: a tool holder including a holder
surface having a bore extending rearward through the holder
surface, a relieved portion surrounding the bore and defining an
inner edge of the holder surface, the holder surface having an
outer edge spaced from the bore; a cutting bit including a body
having a front cutting tip, a rearward projecting shank rotatably
mounted in the bore, and a rearward facing bit shoulder disposed at
a front end of the shank; the shank being rotationally symmetric
about a longitudinal axis of the cutting bit, and a washer disposed
between the bit shoulder and the holder surface, the washer
comprising a front surface including a portion in sliding
engagement with the bit shoulder, a back surface contacting the
holder surface, an inner bore receiving the rearward projecting
shank, the back surface of the washer including an axially
symmetric protruding portion received in the relieved portion of
the tool holder to inhibit lateral motion between the washer and
the tool holder, and an axially asymmetric lip portion joining
outer perimeters of the front and back surfaces, the axially
asymmetric lip engaging a portion of the holder surface outer edge
to inhibit rotation of the washer relative to the holder
surface.
2. The cutter tool of claim 1 further comprising a sleeve
surrounding the cutting bit shank including a forward edge
confronting the protruding portion of the back surface of the
washer to retain the washer on the cutting bit adjacent to the
rearward facing bit shoulder.
3. The cutter tool of claim 1 wherein the lip comprises a rearward
extension along an outer edge of the back surface of the
washer.
4. The cutter tool of claim 1 wherein the lip comprises a linear
outer edge portion on a radially outer surface of the washer.
5 The cutter tool of claim 1 wherein the washer outer edge is in
the form of an ellipse, and the lip is positioned on the back
surface of the washer on a major axis of the ellipse.
6. The cutter tool of claim 1 wherein the washer outer edge is in
the form of a rectangle.
7. The cutter tool of claim 1 wherein the washer front surface
includes an outer tapered portion and an inner tapered portion,
both tapered portions tapering away from a circular line in sliding
contact with the rearward facing bit shoulder.
8. A cutter assembly comprising a cutting bit and a washer, the
cutting bit comprising a body forming a forward cutting tip, a
rearward extending shank, and a rearward facing bit shoulder
disposed at a forward end of the shank; the shank being
rotationally symmetric about a longitudinal axis of the cutting
bit, the washer including an inner edge defining a central hole
receiving the cutting bit shank, a front surface and a back surface
joined by an outer edge of angularly variable radius, the front
surface including an outer tapered portion and an inner tapered
portion, both tapered portions tapering away from a circular line
in sliding contact with the rearward facing bit shoulder, and an
outer edge including an asymmetric lip for engaging an outer
shoulder of a holder to inhibit rotation of the washer relative to
the holder.
9. The cutter assembly of claim 8 further comprising a sleeve
surrounding the cutting bit shank including a forward edge
positioned to confront the back surface of the washer adjacent the
inner edge for retaining the washer on the cutting bit adjacent to
the rearward facing bit shoulder.
10. The cutter assembly of claim 9 wherein the washer central hole
includes a smooth inner surface facilitating rotation of the
cutting bit relative to the washer.
11. The cutter assembly of claim 10 wherein the lip comprises a
linear rearward extension along an outer edge of the back surface
of the washer.
12. The cutter assembly of claim 10 wherein the back surface of the
washer includes an axially symmetric protruding portion for
inhibiting lateral movement of the washer.
13. A washer comprising a front surface and a back surface, an
inner edge connecting the front and back surfaces and defining a
central hole about an axis passing through the central hole, an
outer asymmetric edge of angularly variable radius from the axis
connecting the front and back surfaces, the back surface including
an annular protrusion immediately surrounding the central hole and
the front surface including a ring shaped elevated portion between
the inner and outer edges.
14. The washer of claim 14 wherein the inner edge includes a smooth
surface inner bore facilitating rotation of articles within the
bore relative to the washer.
15. The washer of claim 14 wherein the outer edge is generally
rectangular.
16. The washer of claim 14 wherein the outer edge comprises a
linear rearward extension along an outer edge of the back surface
of the washer.
17. The washer of claim 14 wherein the outer edge comprises an
ellipse having a lip is positioned on the back surface of the
washer on a major axis of the ellipse.
18. The washer of claim 14 wherein the ring shaped elevated portion
of the front surface is defined by an outer tapered portion and an
inner tapered portion, both tapered portions tapering away from the
ring shaped elevated portion.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation-in-part of my
co-pending application Ser. No. 10/171,939 filed Jun. 14, 2002.
BACKGROUND OF THE INVENTION
[0002] The present invention relates generally to road milling and
trenching machines and more particularly to apparatus for
preventing wear on the face of blocks or holders that are used for
retaining cutting bits on such road milling, trenching and other
machines.
[0003] Conventional road milling and trenching machines utilize
cutting bits mounted in cutting systems that in normal operations
move with respect to a work surface. The cutting systems typically
include a plurality of cutting bit holders or blocks that include a
bore. Each of the cutting bits includes a cutting surface located
at a forward or distal end of the cutting bit that is intended to
contact the work surface to mill or mine material from the work
surface. Each of the cutting bits also includes a shank located at
a rearward or proximal end of the cutting bit that is received in a
bore in a cutting bit holder or block.
[0004] During use, impacts between the cutting bits and the work
surface cause the cutting bits to rotate with respect to the
holder. The impact induced rotation also causes relative movement
between confronting surfaces of the cutting bit and holder. The
environment in which such machines are typically operated generally
includes abrasive particulate materials that are displaced from the
work surface and can be entrained between the confronting surfaces
of the cutting bit and holder. The relative movement in the
presence of the abrasive particulate materials causes significant
frictional wear that can result in a variety of failure modes for
the cutting system.
[0005] Attempts have been made to focus the wear on cutting system
elements that are easily replaced, such as the cutting bits, rather
than on the system elements that are more or less permanent
portions of the cutting system, such as the cutting bit holders.
For example, the cutting bit shank is typically rotatably mounted
within a sleeve that is received within the bore of the cutting bit
holder. Preferable the sleeve is sized so that the sleeve tightly
grips or engages the bore of the cutting bit holder and does not
rotate with respect to the holder. In this way, the frictional wear
occurs on the confronting surfaces of the sleeve and bit shank,
both of which are easily replaced. The conventional sleeves do
nothing to protect other confronting surfaces of the cutting bit
and bit holder. As a result, excessive wear occurs on the face of
the cutting bit holder or block into which the cutting bit shank
extends. After prolonged use, the wear on the face of the holder or
block can become severe enough to require its replacement.
[0006] Several attempts have been made to alleviate this problem.
Beebe, U.S. Pat. No. 4,561,698, discloses a sleeve and wear
protector including an annular flange manufactured as a unitary
wear protector. The unitary wear protector is manufactured of
materials such that the wear protector wears at a rate
substantially coincident with the wear rate of the cutting bit.
However, the unitary wear protector may rotate within the bore,
thus leading to uneven wear of the protector assembly and wear of
the holder or block. Dziak, U.S. Pat. No. 4,489,986, discloses
refers to a retainer element mounted on a cylindrical shank of a
cutter bit. The cutter bit is mounted within a bore of a holder or
block member. The holder or block member includes a cylindrical
outer portion including a groove in which is mounted a rubber or
plastic ring. The ring is received in another groove within a wear
collar that contacts the cutter bit. The rubber or plastic ring
further is symmetric about the axis of the cutter bit, and no means
is provided to inhibit relative rotation between the collar and the
holder or block member. Mercier et al., U.S. Pat. No. 6,113,195,
discloses a washer disposed between the holder and the cutting bit
that is conical (Belleville) so that the washer makes annular line
contact with a shoulder of the cutting bit, and with an edge of the
bore of the holder, in order to effectively seal out abrasive fines
from the bore and thereby reduce the unwanted wear. No provision is
made to inhibit rotation of the washer of Mercier et al, thus
resulting in significant wear of the holder surface facing the
washer.
[0007] O'Neill, U.S. Pat. No. 5,106,166, discloses a unitary sleeve
that has a bore for rotatably receiving a cutting bit. The sleeve
and holder or block are constructed such that the angular position
of the sleeve can be fixed relative to the axis of the aperture in
the sleeve in any one of a plurality of discrete positions. The
sleeve and holder are constructed such that the sleeve can later be
rotated with respect to the axis of the aperture in the holder or
block to another position and then fixed in that position. While
the construction of O'Neill prevents unwanted wear of the forward
facing surface of the block or holder, O'Neill requires that the
block or holder have specific features not commonly present on most
blocks or holders in general use. Thus, the unitary sleeve of
O'Neill is cannot be used to reduce the wear of most blocks or
holders in general use today. Britzke et al, U.S. Pat. No.
5,931,542, discloses a substantially circular wear washer with a
radially inwardly directed key which is adapted to fit within a
slot in a sleeve surrounding the shank of the cutting bit, thereby
interlocking the sleeve and the wear washer. The holder or block
bore includes a keyway which is engaged a radially outwardly
directed key on the sleeve thereby interlocking the retainer sleeve
and wear washer with the holder or block. In the absence of such a
keyway on the interior bore of the holder or block, the sleeve and
washer are free to rotate.
[0008] Kammerer, U.S. Pat. No. 6,508,516, discloses a substantially
circular, planar wear washer with a radially outwardly directed key
which is adapted to fit within a slot in a block or holder to
prevent rotation of the washer. The washer is centered by a close
fit around the shank of the cutting bit, or by soldering the washer
to the sleeve within the block or holder. In the event of wear of
the shank, the wear washer is able to vibrate relative to the face
of the block or holder, thus causing wear of the holder face. Thus
Britzke et al, O'Neill and Kammerer require that the block or
holder have specific features not commonly present on most blocks
or holders in general use, and still do not completely eliminate
the opportunity for significant relative movement between the wear
washer and the block or holder.
[0009] What is needed is a wear washer, which is adaptable for use
on a wide variety of existing holder or blocks that will inhibit or
prevent wear of the forward facing surface of the holder or block.
Preferably the wear washer can be coupled to a wide variety of
conventional cutter bits so that the washer can be replaced with
each replacement of the cutter bit.
SUMMARY OF THE INVENTION
[0010] Accordingly, a cutter tool has a tool holder and a cutting
bit as well as a washer of the present invention. The tool holder
includes a holder surface having a bore extending rearward through
the holder surface and an outer edge spaced from the bore. The
cutting bit includes a body having a front cutting tip, a rearward
projecting shank rotatably mounted in the bore of the tool holder,
and a rearward facing bit shoulder disposed at a front end of the
shank. The shank is rotationally symmetric about a longitudinal
axis of the cutting bit. The washer is disposed between the bit
shoulder and the holder surface. The washer comprises a front
surface in sliding engagement with the bit shoulder, and a back
surface contacting the holder surface. The back surface includes an
axially asymmetric lip engaging the holder surface outer edge so as
to inhibit rotation of the washer relative to the holder
surface.
[0011] The cutting bit and washer can be assembled together to form
a cutter assembly of the present invention. The washer includes an
inner edge defining a central hole receiving the cutting bit shank.
The washer also includes a front surface and a back surface joined
by an outer edge of angularly variable radius. The front surface
includes at least a portion for sliding contact with the rearward
facing bit shoulder. The back surface includes a lip extending
rearward from only a segment of the asymmetric edge for engaging an
outer shoulder of a holder. The lip can be a linear rearward
extension along an outer edge of the back surface of the washer.
Where the washer outer edge is in the form of an ellipse, the lip
can also be positioned on the back surface of the washer on a major
axis of the ellipse. A sleeve surrounding the cutting bit shank
includes a forward edge positioned to confront the back surface of
the washer adjacent the inner edge for retaining the washer on the
cutting bit adjacent to the rearward facing bit shoulder. The
washer central hole includes a smooth inner surface that
facilitates rotation of the cutting bit relative to the washer.
[0012] The portion of the washer in sliding contact with the
rearward facing bit shoulder is generally a circular ring portion.
The washer front surface can include an outer tapered portion
tapering away from the circular ring portion. The washer front
surface can also include an inner tapered portion. Both the inner
and outer tapered portions taper away from the circular ring
portion in sliding contact with the rearward facing bit shoulder.
The outwardly tapered surface tends to inhibit particulate abrasive
material from penetrating passed the circular ring contact portion,
and thus concentrates any frictional wear into a circular pattern
on the rearward facing bit shoulder and the forward facing surface
of the washer. Thus, the tool holder forward surface and the tool
holder bore experience reduced wear, which contributes to enhanced
usable life for the tool holder and more reliable positioning of
the cutting bit in relation to the work surface.
[0013] These and other features and advantages of the present
invention will become apparent from the following description of
illustrative embodiments of the present invention. The description
makes reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is an exploded view of a cutter tool including a tool
holder and a cutting bit as well as a washer of the present
invention.
[0015] FIG. 2 is a side elevation view of a washer of the present
invention.
[0016] FIG. 3 is a side elevation view of a cutting bit and washer
assembly of the present invention, the washer and sleeve being
shown in section.
[0017] FIGS. 4A and 4B are perspective views of the top and bottom
of one embodiment of a washer of the present invention.
[0018] FIGS. 5A and 5B are perspective views of the top and bottom
of another embodiment of a washer of the present invention.
[0019] FIG. 6 is a side elevation view of the washer of FIGS. 4A
and 4B.
[0020] FIG. 7 is an exploded perspective view of another cutter
tool including a tool holder and a cutting bit as well as a washer
of the present invention.
[0021] FIG. 8 is another exploded perspective view of a further
cutter tool including a tool holder and a cutting bit as well as a
washer of the present invention.
[0022] FIG. 9 is a side elevation view of a cutter tool including a
tool holder and a cutting bit as well as a washer of the present
invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0023] FIG. 1 illustrates one embodiment of a cutter tool 10 of the
present invention. The cutter tool 10 includes a tool holder 12, a
cutting bit 14 and a washer 16. The tool holder 12 includes a body
18 having a holder surface 20. The body 18 includes a bore 22
extending through the holder surface 20 and body 18. The bore 22
can include a relieved portion such as the beveled or chamfered
portion 23. An outer edge 24 is spaced from the bore 22 typically
by a distance that varies around the perimeter of the body 18. The
tool holder 12 is generally secured to other apparatus, such as a
milling drum (not shown), by a weld around the bottom perimeter
26.
[0024] The cutting bit 14 includes a body 28 having a front cutting
tip 30 and a rearward facing shoulder 32. Any number of flutes and
scallops can be present on the outer surface of the body 28 between
the tip 30 and the rearward facing shoulder 32. A shank portion 34
projects rearward from the center of the rearward facing shoulder
32. The shank portion 34 can be seen to be rotationally symmetric
about a longitudinal axis Y of the cutting bit 14. A sleeve 36,
typically constructed of a spring steel, surrounds the cutting bit
shank portion 34 and is held on to the shank portion 34 by a
rearward edge 38 of the sleeve 36 confronting a radially protruding
lip 40 adjacent the rear end 42 of the shank portion 34. The sleeve
36 has an outer diameter equal to or slightly exceeding the inner
diameter of the bore 22 so as to be tightly received therein. The
sleeve 36 has an inner diameter that is greater than the diameter
of the shank portion 34 so as to fit somewhat loosely thereon. The
cutting bit 14 is thus able to rotate with respect to the sleeve 36
and the tool holder 12 when the shank portion 34 of the cutting bit
14 is received in the bore 22 of the tool holder 12.
[0025] The washer 16 is disposed between the cutting bit rearward
facing shoulder 32 and the tool holder surface 20. The washer 16
includes a front surface 44 in sliding engagement with the bit
rearward facing shoulder 32. A back surface 46 of the washer 16
contacts the tool holder surface 20. The back surface 46 includes
an axially asymmetric lip 48 for engaging the outer edge 24 of the
tool holder 12 so as to inhibit rotation of the washer 16 relative
to the tool holder surface 20. The washer 16 includes a smooth
inner bore 50 that facilitates rotation of the cutting bit 14
relative to the washer 16. The inner bore 50 is surrounded by an
axially symmetric protruding portion such as sloping or tapered
portion 52 that is received in the beveled or chamfered portion 23
of the tool holder 12 surrounding the bore 22. The diameter of the
bore 50 is preferably slightly smaller than the outside diameter of
sleeve 36. A perimeter surface 54 connects an outwardly tapered
portion 56 of the front surface 44 to the back surface 46. The
perimeter surface 54 is of varying radius measured from the center
of the bore 50, which is coincident with the axis Y of the cutting
bit 14.
[0026] In the embodiment illustrated in FIGS. 2 and 3, the
outwardly tapered portion 56 is seen to extend over a greater
fraction of the washer 16 than the inwardly tapered portion 52. The
washer front surface 44 is also seen to have a circular ring
portion 58 between the inner tapered portion 52 and the outwardly
tapered portion 56 that is in sliding contact with the rearward
facing bit shoulder 32. This larger outwardly tapered portion 56
acts to direct abrasive particulate matter away from the ring
portion 58, thus reducing the rate of wear experienced by the
washer 16 and bit 14. The back surface 46 also includes an inner
edge 60 that is in contact with a forward facing edge 62 of the
sleeve 36, thereby retaining the washer 16 and cutting bit 14
together as an easily handled combination. The back surface 46 also
includes a protruding portion such as the tapered portion 64 that
is adapted to be received in the beveled or chamfered portion 23 in
holder 12.
[0027] The perimeter surface 54 of the washer 16 can assume a
number of shapes that are suitable for use in the present
invention. FIGS. 4A and 4B show a washer 16 with an outer edge 54
in the form of an ellipse. The lip 48 is positioned on the back
surface 46 of the washer 14 on a major axis X of the ellipse. In
FIGS. 5A and 5B, the washer 16 is shown to have a rectangular outer
perimeter surface 54. The lip 48 is seen to have the form of a
linear rearward extension along an outer edge of the back surface
46 of the washer 16. Other perimeter shapes that can be employed
for the present invention will be apparent to those skilled in the
art based on the forgoing examples. In each situation the perimeter
surface 54 is seen to be of varying radius measured from the center
of the bore 50. Further the area of the forward surface 44 in
contact with the rearward facing bit shoulder 32 can be varied so
as occupy a smaller portion as in FIGS. 2 and 3, or a larger
portion as in FIGS. 4-6 wherein the forward surface 44 is
substantially planar and having only a very minor outwardly tapered
portion 56.
[0028] Another cutter tool 70 including a tool holder 72 and a
cutting bit 74 as well as a washer 76 is shown in FIG. 7. The tool
holder 72 includes a body 78 having a holder surface 80. The body
78 includes a bore 82 extending through the holder surface 80 and
body 78. The bore 82 includes a relieved portion such as the
beveled or chamfered portion 83. An outer edge 84 is spaced from
the bore 82 typically by a distance that varies around the
perimeter of the body 78. The outer edge 84 can include one or more
protruding portions 85. The tool holder 72 is generally secured to
other apparatus, such as a milling drum (not shown), by a weld
around the bottom perimeter 86.
[0029] The cutting bit 74 can be similar in construction to cutting
bit 14 shown in FIGS. 1 and 3. The cutting bit 74 includes a body
28 having a front cutting tip 30 and a rearward facing shoulder 32.
Any number of flutes and scallops can be present on the outer
surface of the body 28 between the tip 30 and the rearward facing
shoulder 32. A shank portion 34 projects rearward from the center
of the rearward facing shoulder 32. The shank portion 34 can be
seen to be rotationally symmetric about a longitudinal axis Y of
the cutting bit 74. A sleeve 36, typically constructed of a spring
steel, generally surrounds the cutting bit shank portion 34 and is
held on to the shank portion 34 by a rearward edge 38 of the sleeve
36 confronting a radially protruding lip 40 adjacent the rear end
42 of the shank portion 34. The sleeve 36 has an outer diameter
equal to or slightly exceeding the inner diameter of the bore 82 so
as to be tightly received therein. The sleeve 36 has an inner
diameter that is greater than the diameter of the shank portion 34
so as to fit somewhat loosely thereon. The cutting bit 74 is thus
able to rotate with respect to the sleeve 36 and the tool holder 72
when the shank portion 34 of the cutting bit 74 is received in the
bore 82 of the tool holder 72.
[0030] The washer 76 is disposed between the cutting bit rearward
facing shoulder 32 of the cutting bit 74 and the tool holder
surface 80. The washer 76 includes a front surface 90 in sliding
engagement with the bit rearward facing shoulder 32. A back surface
92 of the washer 76 contacts the tool holder surface 80. The washer
76 includes an axially asymmetric lip 94 that connects an outwardly
tapered portion 88 of the front surface 90 to the back surface 92.
The asymmetric lip 94 is of varying radius measured from the center
of the bore 96, which is coincident with the axis Y of the cutting
bit 74. The asymmetric lip 94 also engages an upwardly protruding
portion 85 the outer edge 84 of the tool holder 72 so as to inhibit
rotation of the washer 76 relative to the tool holder surface 80.
The washer 76 includes a smooth inner bore 96 that facilitates
rotation of the cutting bit 74 relative to the washer 76. The inner
bore 96 is surrounded by an axially symmetric protruding portion 98
that is received in the beveled or chamfered portion 83 of the tool
holder 72 surrounding the bore 82. The engagement between the
axially symmetric protruding portion 98 and the chamfered portion
83 inhibits lateral movement of the washer 76 relative to the tool
holder surface 80. The diameter of the bore 96 can be slightly
smaller than the outside diameter of sleeve 36 so that the washer
76 can be retained on the shank portion 34 of the cutting bit 74.
The sleeve 36 surrounding the cutting bit shank portion 34 can
include a forward edge 37 confronting the protruding portion 98 of
the back surface 92 of the washer 76 to retain the washer 76 on the
cutting bit 74 adjacent to the rearward facing bit shoulder 32.
[0031] Another washer 100 is shown in FIG. 8 that can also be used
in combination with the tool holder 72 and cutting bit 74 described
in connection with FIG. 7. The washer 100 is disposed between the
rearward facing shoulder 32 of the cutting bit 74 and the tool
holder surface 80. The washer 100 includes a front surface 102 in
sliding engagement with the bit rearward facing shoulder 32. A back
surface 104 of the washer 100 contacts the tool holder surface 80.
The washer 100 includes an axially asymmetric lip 106, which is
shown to be rectangular or square, that joins the perimeters of the
upper and lower surfaces 102 and 104. The asymmetric lip 106 can
engage the upwardly protruding portion 85 the outer edge 84 of the
tool holder 72 so as to inhibit rotation of the washer 100 relative
to the tool holder surface 80. The washer 100 includes a smooth
inner bore 108 that facilitates rotation of the cutting bit 74
relative to the washer 100. The diameter of the inner bore 108 can
be slightly smaller than the outside diameter of sleeve 36 so that
the washer 100 can be retained on the shank portion 34 of the
cutting bit 74 by a forward edge 37 of the sleeve 36. The inner
bore 108 is surrounded by an axially symmetric protruding portion
110. The protruding portion 110 is adapted to be received in the
beveled or chamfered portion 83 of the tool holder 72 surrounding
the bore 82. The engagement between the axially symmetric
protruding portion 110 and the chamfered portion 83 inhibits
lateral movement of the washer 100 relative to the tool holder
surface 80.
[0032] FIG. 9 shows the assembled cutter tool 70 consisting of the
tool holder 72 and a cutting bit 74, as previously described, as
well as a washer such as washer 76 or 100. The washer 76,100 is
seen to have a front surface 90 including an outwardly tapered
portion 88. The washer 76,100 also includes an axially symmetric
protruding portion 98, 110 as previously shown in FIGS. 7 and 8
which on the front surface of the washers forms an inwardly tapered
portion similar to portion 52 shown in FIGS. 3, 4A and 5A. The
junction of the outwardly tapered portion 88 of the front surface
90 and the protruding portion 98,110 defines a circular ring
portion 89 between the inner tapered portion and the outwardly
tapered portion 88. This circular ring portion 89 is in sliding
contact with the rearward facing bit shoulder 32 of bit 74. The
larger outwardly tapered portion 88 acts to direct abrasive
particulate matter away from the ring portion 89, thus reducing the
rate of wear experienced by the washer 76, 100 and bit 74.
[0033] Thus the replacable wear washers 16, 76 and 100 are adapted
for use on a wide variety of existing holder or blocks 18, 72 to
inhibit or prevent wear of the forward facing surface 20, 80 by
virtue of either lateral or rotational motion of the washer
relative to the holder or block 18, 72. A wear washer 16, 76 100
can be coupled to a wide variety of conventional cutter bits 14, 74
so that the washer can be replaced by each replacement of the
cutter bit. The replacable wear washers 16, 76 and 100 also act to
exclude abrasive material from between the parts of the cutter tool
10, 70 that are moving relative to each other so that the working
life of the cutter bit and tool holder are extended.
[0034] Although the present invention has been described in
connection with preferred embodiments thereof, those skilled in the
art will appreciate that additions, deletions, modifications, and
substitutions, although not specifically described, can be made
without departing from the spirit and scope of the invention as
defined in the appended claims.
* * * * *