U.S. patent application number 12/835995 was filed with the patent office on 2012-01-19 for spring biased rotatable tool.
This patent application is currently assigned to THE SOLLAMI COMPANY. Invention is credited to Phillip A. Sollami.
Application Number | 20120013168 12/835995 |
Document ID | / |
Family ID | 45466381 |
Filed Date | 2012-01-19 |
United States Patent
Application |
20120013168 |
Kind Code |
A1 |
Sollami; Phillip A. |
January 19, 2012 |
Spring Biased Rotatable Tool
Abstract
A rotatable tool has a tool body that is generally symmetrical
about a longitudinal axis, an enlarged cutting head, and a
rearwardly extending shank. The shank joins the enlarged cutting
head at an annular flange. A compressible sleeve is fitted around
the shank and a wear ring is around the shank at the forward end of
the sleeve. A disc spring is positioned between the radial flange
and the sleeve to remove axial play between the shank and the
sleeve and to seal the parts so that hard particles cannot enter
and interfere with rotation of the tool.
Inventors: |
Sollami; Phillip A.;
(Herrin, IL) |
Assignee: |
THE SOLLAMI COMPANY
Herrin
IL
|
Family ID: |
45466381 |
Appl. No.: |
12/835995 |
Filed: |
July 14, 2010 |
Current U.S.
Class: |
299/104 ;
299/105 |
Current CPC
Class: |
E21C 35/18 20130101;
E21C 35/197 20130101 |
Class at
Publication: |
299/104 ;
299/105 |
International
Class: |
E21C 35/18 20060101
E21C035/18; E21C 35/183 20060101 E21C035/183; E21C 35/197 20060101
E21C035/197 |
Claims
1. A rotatable tool comprising a tool body having a longitudinal
axis, an enlarged cutting head and a cylindrical shank extending
rearwardly of said enlarged cutting head, a hardened tip at a
forward end of said enlarged cutting head, said shank joining said
enlarged cutting head at an annular flange, said cylindrical shank
having an annular shoulder thereon, an annular retainer sleeve on
said shank, said retainer sleeve contacting said annular shoulder
for retaining said retaining sleeve to said shank, said retainer
sleeve also having a forward end, and a disc spring on said shank
axially behind said annular flange.
2. The rotatable tool of claim 1 and further comprising a wear ring
also on said shank behind said annular flange.
3. The rotatable tool of claim 1 wherein said disc spring is
between said forward end of said retainer sleeve and said annular
flange, said retainer sleeve has a compressed diameter for
retaining said shank in a bore of a tool holder, and said disc
spring has a central opening with a diameter less than said
compressed diameter wherein said disc spring urges said retainer
sleeve against said annular shoulder.
4. The rotatable tool of claim 1 and further comprising a second
disc spring on said shank.
5. The rotatable tool of claim 1 wherein said shank has a maximum
radius R1, said annular flange has an annular inner portion joining
a forward end of said shank and an outer portion extending to a
maximum diameter of said annular flange, said annular flange having
a maximum radius R3, said annular inner portion being axially
forward of said annular outer portion, and a boundary between said
inner portion and said outer portion having a radius that is
generally midway between R1 and R3.
6. The rotatable tool of claim 5 wherein said disc spring has an
outer diameter at least equal to an outer diameter of said
flange.
7. The rotatable tool of claim 6 wherein said disc spring is
between said forward end of said retainer sleeve and said annular
flange, said retainer sleeve has a compressed diameter for
retaining said shank in a bore of a tool holder, and said disc
spring has a central opening with a diameter less than said
compressed diameter wherein said disc spring urges said retainer
sleeve against said annular shoulder.
8. A rotatable tool comprising a tool body having a longitudinal
axis, an enlarged cutting head and a cylindrical shank extending
rearwardly of said enlarged cutting head, a hardened tip at a
forward end of said enlarged cutting head, said shank joining said
enlarged cutting head at an annular flange, said cylindrical shank
having an annular shoulder thereon, an annular retainer sleeve on
said shank, said retainer sleeve having means for contacting said
shoulder for retaining said retaining sleeve to said shank, said
retainer sleeve having means for contacting said shoulder for
retaining said retaining sleeve to said shank, said retainer sleeve
also having a forward end, a disc spring between said forward end
of said retainer sleeve and said annular flange wherein said disc
spring urges said retainer sleeve against said annular
shoulder.
9. The rotatable tool of claim 8 and further comprising a wear ring
around said shank, and said wear ring having a surface contacting
said disc spring.
10. The rotatable tool of claim 8 wherein said disc spring is
between said forward end of said retainer sleeve and said annular
flange, said retainer sleeve has a compressed diameter for
retaining said shank in a bore of a tool holder, and said disc
spring has a central opening with a diameter less than said
compressed diameter wherein said disc spring urges said retainer
sleeve against said annular shoulder.
11. The rotatable tool of claim 8 and further comprising a second
disc spring on said shank.
12. The rotatable tool of claim 8 wherein said shank has a maximum
radius R1, said annular flange has an annular inner portion joining
a forward end of said shank and an outer portion extending to a
maximum diameter of said annular flange, said annular flange having
a maximum radius R3, said annular inner portion being axially
forward of said annular outer portion, and a boundary between said
inner portion and said outer portion having a radius that is
generally midway between R1 and R3.
13. The rotatable tool of claim 12 wherein said disc spring has an
outer diameter at least equal to an outer diameter of said
flange.
14. The rotatable tool of claim 13 wherein said disc spring is
between said forward end of said retainer sleeve and said annular
flange, said retainer sleeve has a compressed diameter for
retaining said shank in a bore of a tool holder, and said disc
spring has a control opening with a diameter less than said
compressed diameter wherein said disc spring urges said retainer
sleeve against said annular shoulder.
15. The combination comprising a rotatable tool including a tool
body having a longitudinal axis, an enlarged cutting head and a
cylindrical shank extending rearwardly of said enlarged cutting
head, a hardened tip at a forward end of said enlarged cutting
head, said shank joining said enlarged cutting head at an annular
flange, said cylindrical shank having an annular shoulder thereon,
an annular retainer sleeve surrounding said shank, said retainer
sleeve contacting said shoulder and retaining said retaining sleeve
to said shank, said retainer sleeve also having a forward end, a
tool holder having a forward surface and an axial bore, said shank
and said retainer sleeve inserted into said axial bore, and a
spring disc around said shank and between said annular flange and
said forward surface of said tool holder.
16. The combination of claim 15 wherein an inner opening of said
disc spring has a diameter less than a diameter of said axial bore
and an inner portion of said disc spring contacts said retainer
sleeve and urges said retainer sleeve into said bore.
17. The rotatable tool of claim 15 and further comprising a wear
ring around said shank and also positioned between said annular
flange and said forward surface of said tool holder.
18. The combination of claim 15 wherein one of said wear ring and
said disc spring has an inner opening with a diameter less than a
diameter of said axial bore, and said one of said wear ring and
said disc spring contacts said retainer sleeve wherein said
retainer sleeve is urged into said bore by said one of said wear
ring and said disc spring.
19. The combination of claim 15 wherein said shank has a maximum
radius R1, said annular flange has an annular inner portion joining
a forward end of said shank and an outer portion extending to a
maximum diameter of said annular flange, said annular flange having
a maximum radius R3, said annular inner portion being axially
forward of said annular outer portion, and a boundary between said
inner portion and said outer portion having a radius that is
generally midway between R1 and R3.
20. The combination of claim 15 wherein said disc spring is between
said forward end of said retainer sleeve and said annular flange,
said retainer sleeve has a compressed diameter for retaining said
shank in a bore of a tool holder, and said disc spring has a
central opening with a diameter less than said compressed diameter
wherein said disc spring urges said retainer sleeve against said
annular shoulder.
Description
[0001] The present invention relates to rotatable tools for cutting
machines and in particular to an improved tool that employs a disc
spring to prevent dust particles from entering the tool holder.
BACKGROUND OF THE INVENTION
[0002] Machines that cut hard surfaces such as used in the
trenching and mining industries, and that remove hard surfaces of
concrete and asphalt prior to repaving a roadway require rotatable
tools mounted in a wheel or rotatable drum. The tools have a
tapered forward cutting end and located axially behind the cutting
end is a cylindrical shank that rotatably fits within a
complementary shaped bore of a tool holder. Between the forward
cutting end and the shank, the tool has a rearwardly directed
annular flange that contacts the forward surface of the tool
holder. Force is applied through the rotatable drum or wheel to the
tool holder and through the radial flange to the tool to thereby
force the tool into the hard surface to be cut. The tools are
mounted on the drum at an angle such that rotation of the drum
causes rotation of the tools with the annular flange rotating
against the planar surface of the tool holder.
[0003] To prevent wear to the forward end of the tool holder it has
become customary to provide a wear ring that fits around the
circumference of the shank of the tool with one surface of the wear
ring engaging the annular flange of the tool and the other surface
engaging the forward surface of the tool holder. The useful life of
a tool used in road planing is at most one day during active use of
the machine. It is therefore common to replace all the tools of a
road planing machines at least daily. When the tool is replaced,
the wear ring is also replaced such that the contact is between the
annular flange of a new tool and the forward surface of a new wear
ring.
[0004] In order for the parts to work properly, it is desirable
(but not necessary) that the wear ring itself be non-rotatable with
respect to the tool holder. There are several methods employed for
preventing rotation of the wear ring with respect to the tool
holder, one of which is described in my U.S. Pat. No. 7,229,136 B2
issued Jun. 12, 2007, which is incorporated herein by reference.
Another structure is shown in Britzke, U.S. Pat. No. 5,931,542.
[0005] The tool further has a hardened forward tip that engages the
hard surface to be cut. The rotation of the tool causes the forward
cutting end of the tool to become worn symmetrically around its
longitudinal axis. The rotation of the tool is therefore necessary
to sharpen the hardened tip. Where the tool fails to rotate
properly, the forward cutting end will wear unevenly and the
hardened tip will gradually become blunted or develop a flat
surface and the useful life of the tool will become shortened.
[0006] The rotation of the tool within the tool holder is inhibited
by fine particles cut away from the hard surface by the tool which
work their way between the walls of the cylindrical shank and the
inner surface of a retainer sleeve that retains the tool body in
the tool holder. The particles of debris increase the friction
resisting rotation of the tool and can ultimately prevent rotation
altogether. The retainer sleeve that retains the tool has fingers
that abut a radial flange at the rear end of the tool shank. The
parts are manufactured to a close tolerance and in order that they
may assemble easily, the length of the sleeve is perhaps sixty
thousandths of an inch less than the portion of the shank around
which it is fitted. When the tool is subsequently hammered into a
bore of a tool holder, the forward end of the sleeve is pressed
against the rearward surface of the radial flange of the tool. As a
result, the tool has a longitudinal play. That is, the tool body is
moveable outward of the tool holder by the difference between the
sleeve length (the distance between rear end of the fingers and the
forward end of the sleeve), and the shank length (the distance
between annular ridge of the shank and the radial flange).
[0007] As the drum that retains the tool holder and tool rotates,
centrifugal force causes the radial flange of the tool to move away
from the surface of the tool holder such that fine particles can
enter the spacing between the tool holder and the flange and reach
the spacing between the cylindrical shank and the bore in which it
is received. When the tool subsequently engages the hard surface to
be cut, the flange is rapidly forced against the forward surface of
the tool holder causing hard particles that have worked their way
under the flange to be forced or pumped down the bore of the tool
holder. The play between the tool and tool holder therefore
contribute to the accumulation in the bore of particles that
inhibit rotation. It would therefore be desirable to provide a
retaining structure for retaining the tool in the tool holder
without allowing play between the tool holder and the shank. Such a
structure would prevent the radial flange of the tool from moving
away from the surface of the tool holder as a result of centrifugal
force caused by the drum and thereby block the entry of particles
behind the flange.
SUMMARY OF THE INVENTION
[0008] Briefly, the present invention is embodied in a rotatable
tool for insertion in a bore of a tool holder where the tool has an
enlarged cutting head and extending rearwardly of the enlarged
cutting head, a cylindrical shank. Fitted at the forward end of the
enlarged cutting head is a hardened tip and fitted around the
circumference of the shank is a compressible retainer sleeve. An
annular wear ring having a planar forward surface is positioned
behind the flange. The wear ring rests, without rotating, on the
forward surface of the tool holder and the radial flange is
rotatable on the forward surface of the wear ring.
[0009] The shank of the tool has an annular ridge thereon and an
annular retainer sleeve is fitted around the shank with a portion
of the sleeve contacting the ridge to retain the sleeve to the
shank. The retainer sleeve also has a forward end positioned behind
the radial flange of the tool.
[0010] The length of the retainer sleeve that fits between the
annular shoulder and the flange is many thousandths of an inch less
than the length available on the shank to avoid assembly problems
caused by the tolerance under which the parts are manufactured. As
a result, the sleeve is axially moveable along the shank, that is,
it has axial play along the shank.
[0011] In accordance with the present invention, a hardened disc
spring is fitted behind the annular flange. The disc spring has
concave and convex surfaces in its unstressed condition, but is
axially compressible into a substantially planar configuration when
biased. The disc spring has an axial compression length that is
longer than the axial play of the sleeve along the shank.
[0012] When a tool having a disc spring fitted behind the radial
flange is inserted into the bore of a tool holder, the disc spring
is compressed and prevents axial movement of the tool, or play, in
the tool holder. By preventing axial movement of the tool, the
flange of the tool, the wear ring, and the disc spring are all
snugly retained together and are retained against the forward
surface of the tool holder, thereby preventing fine particles from
entering between the parts.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] A better understanding of the invention will be had after a
reading of the following detailed description taken in conjunction
with the drawings wherein:
[0014] FIG. 1 is a cross-sectional view of a tool assembly having a
disc spring in accordance with the invention;
[0015] FIG. 2 is a cross-sectional view of a tool assembly shown in
FIG. 1 inserted into the forward end of a tool holder;
[0016] FIG. 3 is a fragmentary enlarged cross-sectional view of the
parts shown in FIG. 1;
[0017] FIG. 4 is a fragmentary enlarged cross-sectional view of the
parts shown in FIG. 2;
[0018] FIG. 5 is a front elevational view of a hardened disc spring
used in the tool assembly shown in FIG. 1;
[0019] FIG. 6 is a cross-sectional view of the disc spring and the
tool assembly shown in FIG. 5 taken through line 6-6 thereof;
[0020] FIG. 7 is a side elevational view of a tool assembly having
a disc spring in accordance with another embodiment of the
invention;
[0021] FIG. 8 is an enlarged fragmentary cross-sectional view of
the assembly shown in FIG. 7 with the wear ring assembled and the
assembly attached to a tool holder;
[0022] FIG. 9 is a cross-sectional view of another embodiment of a
tool assembly having a disc spring in accordance with the
invention;
[0023] FIG. 10 is a fragmentary enlargement of the cross-section of
FIG. 9 showing more clearly the contact between the disc spring and
adjacent parts;
[0024] FIG. 11 is a cross-sectional view of yet another embodiment
of a tool assembly having a plurality of disc springs in accordance
with the invention;
[0025] FIG. 12 is a fragmentary enlargement of the cross-section
shown in FIG. 11 showing the contact surfaces of the disc
springs;
[0026] FIG. 13 is a cross-sectional view of a typical existing tool
body fitted with a disc spring in accordance with the invention;
and
[0027] FIG. 14 is a fragmentary enlargement of FIG. 14.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0028] Referring to FIGS. 1 and 3, a tool assembly 10 in accordance
with the present invention is suitable for mounting in a tool
holder 11. Where the tool holder 11 is a quick-change tool holder
such as described in my previous U.S. Pat. Nos. 6,371,567 B1,
6,585,326 B2 and 6,685,273 B1, the text of which are all
incorporated herein by reference, the tool holder 11 has an
enlarged forward portion 12 and extending rearwardly of the
enlarged forward portion 12 is a tubular rearwardly extending shank
14 for attachment to a base block unit, not shown, which in turn is
welded to the drum of a machine, also not shown. The tool holder 11
also has a generally planar forward surface 16 and a bore 18, the
axis of which is perpendicular to the planar forward surface
16.
[0029] The tool assembly 10 has a tool body 19 that is generally
symmetrical about a longitudinal axis 20 and includes an enlarged
forward cutting head 22 at the very forefront of which is a
hardened tip 24. The enlarged forward cutting head 22 diverges
radially outwardly from the tip 24 to a maximum diameter at the
rearward end thereof with a rearward surface forming an annular
flange 28. Extending axially from the center of the annular flange
28 is a cylindrical shank 30. Fitted around the cylindrical shank
30 is a compressible sleeve 32 that is retained to the shank 30 by
an annular ridge 34 at the distal end thereof. The compressible
sleeve 32 has a plurality of rearwardly directed fingers 33-33 each
of which is bent at a small angle so as to partially project
radially inwardly. The fingers 33-33 contact the annular ridge 34
on the shank 30 of the tool body 19 to retain the tool body 19 in
the bore 18. Fitted around the circumference of the shank 30 and
the forward end of the sleeve 32 is an annular wear ring 36.
[0030] The sleeve 32 is preferably made of a spring steel and has
an unstressed diameter that is larger than the diameter of the bore
18 of the tool holder 11. When the shank 30 of the tool assembly 10
is inserted into the bore 18, the sleeve 32 is compressed or
collapsed until the outer diameter thereof tightly fits within the
bore 18 and the inner diameter is a little larger than the diameter
of the shank 30 around which it is fitted. Accordingly, the sleeve
32 will hold the tool assembly 10 within the bore 18 and yet allow
the tool body 19 to rotate therein.
[0031] Referring to FIGS. 3 and 4, in accordance with the present
invention, the surface of the annular flange 28 is not planar.
Instead, the flange 28 has an annular inner portion 50, the inner
circumference of which is contiguous with the outer circumference
of the cylindrical shank 30, and an outer portion 52, the outer
circumference of which is contiguous with the maximum diameter of
the enlarged cutting head 22. Between the inner portion 50 and the
outer portion 52, the surface of the annular flange has an annular
midportion 54 which extends between the outer circumference of the
inner portion 50 and the inner circumference of the outer portion
52.
[0032] The annular inner portion 50 has an inner radius equal to
the radius R1 of the shank 30 and outer portion 52 has an outer
diameter R3 equal to the maximum diameter of the flange 28. An
abrupt annular boundary joins the outer circumference of the
midportion 54 to the inner circumference of the outer portion 54.
The inner portion 50 is positioned axially forward of the outer
portion 52 by a short distance 56. I have found that the distance
56 between the axial positions of the inner portion 50 and outer
portion 52 need only be a small distance of perhaps 0.020 of an
inch. The annular midportion 54 which transits the distance 56
between the inner and outer portions 50, 52 is concave and may have
any configuration because the contour of the midportion 54 is not
important to the invention. As shown in FIG. 3, the midportion 54
may be inversely frustoconical, but it may also be semispherical,
or any other contour as may be formed during the manufacture of the
part. As can be seen in FIG. 3, the inner portion 50 and the
midportion 54 extend across a significant portion of the surface of
the flange 28. The boundary between the midportion 54 and the outer
portion 52 has a radius R2 that falls midway between R1 and R3.
Preferably, R2 is approximately equal to or greater than one half
the sum of the radius R1 of the shank 30 and the radius R3 of the
annular flange 28.
[0033] Referring to FIGS. 1, 3 and 4, the wear ring 36 has a
generally planar forward surface 38 that is positioned behind the
rearward surface of the flange 28, a parallel planar rearwardly
facing surface 40 that contacts the forward surface 16 of the tool
holder 11, a cylindrical outer wall 42, and a generally cylindrical
central opening 44. Preferably, the compressible sleeve 32 and wear
ring 36 are of the type disclosed in my previously issued U.S. Pat.
No. 7,229,136 B2 such that the wear ring 36 is retained against
rotation with respect to the sleeve 32 by means of a projection 46
on the inner opening 44 of the wear ring 36 that extends into a cut
out portion 48 in the compressible sleeve 32. My U.S. Pat. No.
7,229,136 B2 is incorporated herein by reference to provide a more
comprehensive description of these parts.
[0034] Referring to FIGS. 3 through 6, positioned between the rear
surface of the flange 28 and the forward surface 38 of the wear
ring 36 is an annular disc spring 60 having a circular central
opening 62 and a circular outer circumference 64. It is important
that the radius of the central opening 62 is a little larger than
R1 so as to slideably receive the shank 30, but smaller than the
outer diameter of the collapsed sleeve 32. As a result, the inner
portion of the disc spring 60 will abut the forward end of the
sleeve 32 as is further described below. The radius of the outer
circumference 64 is preferably at least equal to the radius R3 of
the flange 28. In its unbiased condition, the disc spring 60 also
has a convex surface 63 and a concave surface 65. In its unbiased
conditioned, the portion of the disc spring nearest to the central
opening 62 extends a compressive distance 66 forward of the outer
circumference 64 of the part. Under a compressive force, the
portion around the central opening 62 can be moved a compressive
distance 66 until the opening 62 is nearly in planar alignment with
the outer circumference 64.
[0035] As shown in FIG. 3, when the disc spring 60 is assembled in
a tool body 19 having a flange 28 with a concave inner portion 50
and midportion 54, the disc spring 60 is oriented with the convex
surface 63 extending into the concave inner portion 50 and
midportion 54 of the flange 28 and the outer circumference of the
concave surface 65 contacting the forward surface 38 of the wear
ring 36.
[0036] The sleeve 32 cannot be manufactured with sufficient
precision to snugly fit on the shank 30 with the fingers 33-33
contacting the annular ridge 34 and the forward end of the sleeve
32 contacting the flange 28. The parts can only be manufactured to
tolerances of twenty to eighty thousandths of an inch. The sleeve
length, that is the distance from the ends of fingers 33-33 to the
forward end of the sleeve 32, is therefore made about sixty
thousandths of an inch less than the distance between the annular
ridge 34 and the flange 28 of the tool body 19. The sleeve 32
therefore has several thousandths of an inch of "play," that is,
room for longitudinal movement along the length of the shank 30 to
which it is assembled. In FIG. 1, the sleeve 32 is depicted with
the forward end thereof abutting the concave surface 65 of the disc
spring 60 and the disc spring 60 abutting the flange 28 leaving
play 35 between the end of the fingers 33 and the annular ridge 34.
The disc spring 60 that is fitted around the shank 30 has a
compressive distance 66 that is greater than the play 35 between
the sleeve 32 and the shank 30.
[0037] When a prior art tool without a disc spring 60 is inserted
into the bore 18 of a tool holder 11, the sleeve is pressed into
the bore 18 by the radial flange or by a radial shoulder on the
shank. The play therefore allows the tool body to be thrown outward
of the tool holder 11 by centrifugal force as the drum on which the
tool holder is attached rotates. Loose particles in the air
surrounding the drum will work under the radial flange and into the
space between the sleeve and the tool shank. The axial movement of
the tool body as it is alternately thrown outward of the tool
holder by centrifugal force then hammered back in as the tool
contacts a hard surface drives loose particles from under the
flange into the bore of the tool holder where they inhibit rotation
of the tool.
[0038] Referring further to FIGS. 1, 2, 3, and 4, when a tool 10 in
accordance with the present invention is inserted into the bore 18
of a tool holder 11, and the shank 30 is driven into the bore 18
with a hammer, the planar outer portion 52 of the flange 28 applies
pressure to the disc spring 60 around the annular boundary at R3 to
flatten the disc spring 60. As the disc spring 60 flattens the
portion around the central opening acts like the end of a lever arm
and forces the sleeve 32 rearward with respect to the shank 30
until the fingers 33-33 abut the annular ridge 34 of the shank 30
as shown in FIG. 2. The lever action of the disc spring 60 causes
the sleeve 32 to be pushed so deep into the bore 18 that it absorbs
all play 35 between the sleeve 32 and the shank 30. I have found
that the sleeve 32 will often apply such pressure against the ridge
34 that it will interfere with the rotation of the tool body 19
within the tool holder 11. However, one additional blow to the tool
head 22 with a hammer will loosen the tool body 10 from the sleeve
32 and allow it to rotate.
[0039] Once installed, the fingers 33-33 of the sleeve 32 will
retain the flange 28 of the tool flush against the surface of the
disc spring 60 and the wear ring 36. Also, the inner circumference
62 of the disc spring 60 is compressed against one member of the
tool assembly 10 and the outer circumference 64 is compressed
against another member such that the disc spring 60 acts as a seal
between the parts and prevents hard particles from entering between
the parts to reach the bore 18 of the tool holder 11.
[0040] The disc spring 60 will also reduce the incidence of
breakage of the carbide tips 24 which occurs when the tool body 19
contacts an inordinately hard object such as a metal pipe. This is
because the attachment of the tool assembly 10 to a tool holder 11
does not result in the entire compressive distance 66 of the disc
spring 60 being consumed. The unconsumed portion of the compressive
distance 66 allows the tool body 19 to move relative to the tool
holder 11 in response to contact with an inordinately hard object
thereby distributing the force of the impact load over a longer
distance. The result is that the tool assembly 10 is more forgiving
and less likely to result in breakage of the carbide tip.
[0041] Referring to FIGS. 7 and 8, where the play 35 cannot be
absorbed using a disc spring 60 configured as above, the disc
spring 60 can be reversed. In this embodiment, a tool assembly 70
has a tool body 71 with an enlarged forward portion 72, a radial
flange 74, and a cylindrical shank 76 that extends rearward from
the center of the flange 74. An annular ridge 78 extends around the
rearward end of shank 76 and a compressible sleeve 80 is fitted
around the shank 76 with fingers, unnumbered, that engage the
annular ridge 78 to retain the sleeve 80 to the shank 76. A wear
ring 82 is fitted around the forward end of the shank 76 and the
rearward surface of the wear ring 82 is adapted to contact the
forward surface of the tool holder 84.
[0042] In this embodiment, the disc spring 60 is positioned between
the rearward surface of the flange 74 and the forward surface of
the wear ring 82 with the convex surface 63 of the disc spring 60
directed toward the wear ring 82. As shown in FIG. 7, when the
sleeve 80 is fitted around the shank 76, the disc spring 60 is
partially compressed thereby taking out the play between the sleeve
80 and the shank 76.
[0043] When the tool assembly 70 is inserted into the tool holder
84, as depicted in FIG. 8, the disc spring 60 will retain the wear
ring 82 flush against the forward surface 86 of the tool holder 84
and hard particles in the surrounding air will be unable to work
between the wear ring 82 and the tool holder 84. Also, the central
opening 62 of the disc spring 60 will fit tightly enough around the
circumference of the shank 76 and the outer circumference 64 of the
disc spring 60 will fit tightly against the surface of the wear
ring 82. The force axially applied by the disc spring 60 will cause
all the elements of the tool assembly 70 including the flange 74,
the sleeve 80, the wear ring 82, and the disc spring 60 itself to
be tightly compressed together thereby preventing dust particles
from entering between the parts. The disc spring 60 will therefore
block dust particles from entering between the inner wall of the
sleeve 80 and the surface of the shank 76 of the tool body 71.
[0044] The disc spring 60 may be positioned between the radial
flange (such as flanges 28 and 74 described above) and a wear ring
(such as wear rings 36 and 82 described above) or it may be
positioned rearward of the wear ring. Referring to FIGS. 9 and 10,
a tool body 90 has a radial flange 92 and a shank 94. A
compressible sleeve 96 is fitted around the shank 94 and a wear
ring 98 is positioned immediately behind the radial flange 92. In
this embodiment the wear ring 98 extends around a forward portion
100 of the shank 94 having a diameter that is larger than that for
the portion around which the sleeve 96 is fitted thereby forming a
shoulder 102. The disc spring 60 is positioned between the rearward
surface of the wear ring 98 and the forward end of the sleeve 96.
The concave surface 65 is directed toward the wear ring 98 and the
convex surface 63 is directed toward the sleeve 96 such that the
disc spring 60 will urge the sleeve 96 away from the radial flange
92 to thereby remove any play between the sleeve 96 and the shank
94. As with other embodiments, the disc spring 60 will also cause
the annular parts to be compressed together thereby sealing the
parts against the entry of dust particles.
[0045] Referring to FIGS. 11 and 12, in some circumstances, as for
example when the play between a sleeve and a shank is large, it may
be desirable to provide more than one disc spring 60. In the
embodiment depicted, a tool body 110 has a radial flange 112, a
shank 114 with a shoulder 116. A sleeve 118 is fitted around the
shank 114 forward of the shoulder 116. A first disc spring 60 is
fitted between the wear ring 120 and the radial flange 112 and a
second disc spring 60' is fitted between wear ring 120 and the
sleeve 118. In this embodiment, the compressive distance of both
disc springs 60, 60' will be combined to absorb the play between
the sleeve 118 and the shank 114. The disc springs 60, 60' will
thereby urge the sleeve 96 deep into the bore of a tool holder into
which it is inserted and it will seal the parts to thereby prevent
hard particles from entering around the parts to reach the
bore.
[0046] Referring to FIGS. 13 and 14, the disc spring 60 can be used
with any existing tool body of which tool body 130 is a typical
example. It is desirable that the element immediately forward of
the compressible sleeve 132 have an inner diameter that is less
than the outer diameter of the collapsed sleeve 132. In this
embodiment, the wear ring 134 is immediately forward of the sleeve
132 and has an inner diameter smaller than the outer diameter of
the collapsed sleeve such that the wear ring 134, under pressure
from the disc spring 60, will urge the sleeve 132 rearwardly to
remove play between the sleeve 132 and the shank 136. It is the
addition of the disc spring 60 to the tool assembly that causes the
parts to be sealed. A tool assembly in accordance with this
invention has been found to have a useful life that is fifty
percent longer than a prior art tool assembly.
[0047] The purpose of the wear ring is to protect the planar
forward surface (surface 16 in FIGS. 1 and 2) from wear as the tool
rotates in the tool holder. It should be appreciated that a tool
assembly that includes disc springs, such as a disc spring 60, may
function without a wear ring. To function without a wear ring, the
disc spring should be oriented with the convex surface directed
toward the flange of the tool and the concave surface directed
toward the forward surface of the tool holder. In this
configuration, there will be greater resistance to rotation around
the outer circumference of the disc spring where it contacts the
tool holder than around the inner circumference that contacts the
shank of the tool. As a result, the disc spring will not rotate
with the tool.
[0048] While the present invention has been described with respect
to two embodiments, it will be appreciated that many modifications
and variations may be made without departing from the spirit and
scope of the invention. It is therefore the intent of the appended
claims to cover all such modifications and variations that fall
within the spirit and scope of the invention.
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