Note: Descriptions are shown in the official language in which they were submitted.
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CUTTING TOOL ASSEMBLY WITH AN ECCENTRIC DRIVE MEMBER
[0001]
FIELD OF THE INVENTION
[0002] This invention is related to a tool holder assembly having a tool
holder
and an interlocking cutting tool.
BACKGROUND AND SUMMARY OF THE INVENTION
[0003] The tool holder assembly is connected to a conventional drive
spindle.
The tool holder is received in a rotatable spindle. The tool holder has an
elongated .body having an axial bore in the lower end. The cutting tool
includes a stepped shank that is telescopically received in the body. A
retention sleeve cooperates with a cammed pin to releasably interlock the
cutting tool to the tool holder body by drawing the cutting tool into a
contoured axial opening in the body.
[0004] In my previous United States Patent Application Serial No.
11/619,666
filed January 4, 2007, now Patent No. 7,527,459, I described a cutting tool
shank and the tool holder having complementary polygonal drive sections
that ensure that there are multiple flat surfaces that create an
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interference fit upon rotation of the cutting tool and resist deflection when
the
cutting tool is cutting. The interference fit provided a desired resistance to
deflection or rigidity between the removable cutting tool and the machine
mounted tool holder. This polygonal drive section, however, utilizes an
axially
mounted threaded member or "drawbar" that pulls the cutting tool into the tool
holder. While the drawbar configuration is effective to rigidly mate the
cutting tool
and tool holder, the tool holder must be removed from the spindle to change
cutting tools.
[0005] The present invention eliminates the drawbar while providing a rigid
interference fit between the cutting tool and tool holder. Complementary oval
or
elliptical shaped drive portions are provided allowing the cutting tool to
partially
rotate within the tool holder until opposite facing portions of the outer wall
of the
oval section of the cutting tool's shank abut a complementary-shaped, albeit
slightly larger, inner wall of an opening in the tool holder.
[0006] The present invention further includes a cylindrical retention
sleeve which
is received within the tool holder opening ahead of the cutting tool shank.
The
sleeve includes an eccentrically shaped opening that receives a lobed head on
the end of the shank prior to rotating the shank within the tool holder, once
the
shank is rotated within the tool holder and the drive portions abut, the lobed
head
is locked axially within the eccentric sleeve opening. A cammed pin passing
laterally through the sleeve and tool holder draws the sleeve and the
interlocked
shank into the tool holder.
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[0007] The broad purpose of the present invention is to provide a tool
holder
chucking structure providing a positive drive member and limiting movement of
the cutting tool relative to the tool holder while allowing the cutting tool
to be
quickly connected and disconnected from the tool holder.
[0008] One advantage of the present invention is that is provides a cutting
tool to
tool holder interface having two distinct sections: an oval interface and a
tapered
interface.
[0009] Another advantage of the present invention is that it includes a
third
cylindrical interface between the cutting tool and tool holder that resists
movement of the cutting tool along the angled profile of the tapered
interface.
[0010] Still another advantage of the present invention is that it provides
a quick
disconnect feature allowing the cutting tool to be rapidly and easily removed
from
and attached to the tool holder to minimize machine downtime.
[0011] Still further objects and advantages of the invention will become
readily
apparent to those skilled in the art to which the invention pertains upon
reference
to the following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The description refers to the accompanying drawings in which like
reference characters refer to like parts throughout the several views, and in
which:
[0013] FIG. 1 illustrates a cutting tool assembly embodying the invention;
[0014] FIG. 2 is an exploded view of the major components of the tool
assembly;
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[0015] FIG. 3 is an enlarged partial perspective view of the upper shank
end of
the cutting tool;
[0016] FIG. 4 is cross-sectional view through the driver portion of the
shank;
[0017] FIG. 5 is a longitudinal sectional view through the tool assembly of
FIG. 1
with the cutting tool in a pre-rotated position;
[0018] FIG. 6 is a longitudinal sectional view through the tool assembly of
FIG. 1
with the cutting tool in a post-rotated position;
[0019] FIG. 7 is a sectional view as seen along lines 7-7 in FIG. 9,
illustrating the
driver portion in a post-rotated abutting engagement with the drive walls of
the
tool holder's axial opening;
[0020] FIG. 8 is a perspective view of the camming pin;
[0021] FIG. 9 is a longitudinal sectional view through the tool assembly of
FIG. 1
with the cutting tool in a post-rotated position and the camming pin rotated
to
releasably interlock the cutting tool to the tool holder by wedging their
complementary tapered sections together;
[0022] FIG. 10 is a sectional view as seen along lines 10-10 of FIG. 9,
illustrating
the camming pin engaging the retention sleeve to draw the cutting tool's shank
further into the tool holder's axial opening to releasably interlock the
cutting tool
to the tool holder; and
[0023] FIG. 11 is a perspective view of the bottom end of the retention
sleeve.
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DETAILED DESCRIPTION OF THE INVENTION
[0024]
Referring now to the FIGs., a preferred tool assembly 10 is illustrated for
joining a cutting tool 12, such as an end mill, to a rotatable drive spindle
14,
shown in phantom. The tool can be any of a variety of rotatable cutting tools.
The spindle is conventional and is used in a variety of commonly used turning
or
machining centers. For the purposes of this invention disclosure the term oval
and oval-shaped shall be considered to describe any continuous, non-circular,
closed plane curve, and generally including an ellipse or elliptical shape.
[0025] As shown
in FIG. 2, tool assembly 10 comprises a cutting tool 12, a tool
holder 16, a retention or draw sleeve 18 and a camming pin 20.
[0026] Tool
holder 16 is an elongated generally cylindrical bar having a stepped
axial bore or opening 22 formed into its bottom end 24. The outer surface 25
of
the tool holder 16 is preferably sized to be received within a machine tool
spindle,
such as spindle 14, or other type of chucking device. Tool holder 16 may also
include additional chucking features such as a set-screw receiving recess or
flat
portion 26. It should be appreciated that while the present invention is
illustrated
having a substantially cylindrical spindle mating upper end, the upper end of
tool
holder 16 can be made having various spindle mating shapes and sizes, such as
a conventional CAT style v-flange configuration.
[0027] Axial
bore 22 has a stepped, shank-receiving profile that is divided into
three distinct sections 28, 29, and 30. Referring to FIGs. 2, 5 and 6, axial
bore
22 at its lower-most end of the elongated body of tool holder 16 opens into
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tapered or conical section 28. Walls 32 of section 28 narrow radially inward
to
drive section 29.
[0028] Drive section 29 of axial bore 22, as best illustrated in FIG. 7, is
defined by
a drive wall 33 having an eccentric cross-sectional shape with a pair of
opposed
drive members 33a extending radially inward to define a generally oval cross-
sectional shape. Drive wall 33 runs parallel to the longitudinal axis 34 of
bore 22.
[0029] Referring back to FIGs. 2, 5 and 6, drive section 29 runs to the
cylindrical
support section 30. In section 30 of axial bore 22, the oval shaped walls of
section 29 terminate and steps down to cylindrical wall 35. Cylindrical wall
35
preferably has a diameter that is smaller than the length of the minor axis of
the
oval-shaped drive section 29. In this manner, an annular seat 36 is formed
between drive section 29 and support section 30.
[0030] Tool holder 16 also has a lateral lock-pin aperture 37 formed
through the
outer surface perpendicular to axial bore 22. Aperture 37 intersects the
cylindrical support section 30 and is preferably tapped at one 37a end to
receive
a threaded body.
[0031] Referring now to FIGs. 1-7, cutting tool 12 is illustrated. Cutting
tool 12
includes a lower end 38 that presents a cutting edge to a workpiece. It should
be
appreciated that lower end 38, shown in FIG. 1, as an indexable insert-based
end mill is for illustrative purposes only and that any type of rotating
cutting tool
can be used.
[0032] The upper end of cutting tool 12 is a stepped shank 389 having four
portions 40, 41, 42, and 43 which are telescopically received within axial
bore 22.
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The first three portions 40, 41, and 42 being generally complementary in shape
to axial bore sections 28, 29, and 30, respectively. As will be described in
greater detail below, the tool holder's drive section 29 and its shank
counterpart
41, while being substantially the same cross-sectional shape, are sized to
permit
a limited amount of rotational movement when the shank 39 is received within
bore 22. The fourth portion 43 cooperates with the retention sleeve 18 to
releasably interlock the cutting tool 12 to the tool holder 16.
[0033] Portion
40 extends axially from lower end 38 as a frustoconical wall 44
that tapers inwardly from a larger diameter where portion 40 meets lower end
38
to driver portion 41.
[0034]
Extending away from tapered portion 40 is tool driver portion 41. Portion
41 has a driver wall 45 that extends axially from the upper-most end of the
tapered portion 40 parallel to the longitudinal axis 46 of cutting tool 12
[0035] As best
shown in FIGs. 4 and 7, driver wall 45 has an eccentric or oval
cross-sectional shape with a pair of lobes 45a extending radially from
diametrically opposed sides of a central generally cylindrical hub. These
diametrically opposed projections preferably project to define a uniform oval
shape, such as an ellipse. This
oval shape having the same general
configuration as drive section 29 while being slightly smaller in size than
the
opening in drive section 29. That is, a ratio of the lengths of the minor and
major
axes of the driver portion 41 is preferably equal to the ratio of the minor
and
major axes of the drive section 29.
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[0036] In the preferred embodiment, drive section 29 has an oval cross-
sectional
shape having a longer major axis and a shorter minor axis. Importantly, while
the
minor and major axis lengths of the shank's driver portion 41 are smaller than
their axial opening drive section 29 counterparts, the length of the major
axis,
denoted 47, of the shank's driver portion 41 is larger than the length of the
minor
axis, denoted 48, of the axial bore's drive section 29. In this manner, when
the
driver portion 41 is mated within the drive section 29, the cutting tool 12 is
permitted to rotate a limited amount within the axial bore 22 until a leading
surface 45b of the driver wall 45 abuts drive member 33a of the tool holder's
drive wall 33. In the preferred embodiment, the oval-cross sections of both
the
drive section 29 and the driver portion 41 are elliptical causing two surfaces
45b
located on opposite sides of the driver wall 45 to simultaneously abut
opposing
portions 33a of the drive wall 33.
[0037] Referring to FIGs. 2, 3, 5, and 6, portion 42 of shank 39 is a
cylindrical
support shaft 50 that extends axially from the oval driver portion 41. Shaft
50 is
sized complementary to support section 30 in axial bore 22 and is preferably a
slip fit. The cross-sectional diameter of support shaft 50 is preferably equal
to
the length of the minor axis, denoted 51, of the adjacent driver portion 41
resulting in the upper surface of the driver portion 41 forming a shoulder 41a
as
the major axis 47 of the oval driver portion extends radially beyond shaft 50.
[0038] The tight fit between section 30 and support shaft 50 prevents the
cutting
tool from tilting or rotating along the complementary tapered walls 32 and 44.
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[0039] Shank 39 terminates at a fastener portion 43, which extends from the
upper face 50a of the cylindrical support shaft 50. Fastener portion 43
includes
an oblong fastener head 52 projecting from a cylindrical neck 54, which
extends
axially from shaft 50. Head 52 is oblong having a pair of lugs 56 projecting
radially in opposite directions from a central circular hub 58. In the
preferred
embodiment, the two lugs 56 are aligned with and extend radially from
longitudinal axis 46 in the same direction as the major axis 47 of the driver
portion 41.
[0040] Tool assembly 10 also includes a retention sleeve 18. Sleeve 18 is a
cylindrical rod 60 having a diameter approximately equal to the diameter of
support shaft 50 resulting in rod 60 being telescopically receivable in
support
portion 30 of the tool holder in a slip-fit relationship.
[0041] The bottom end of rod 60 has an oblong opening 62 shaped
complementary to and sized to allow fastener head 52 to pass therethrough. An
enlarged circular opening 64 depends from oblong opening 62 allowing the head
52 to rotate freely within rod 60 when head 52 and neck 54 are inserted into
openings 62, 64. As best shown in FIGs. 5 and 6, the oblong shape of opening
62 and the adjacent enlarged opening 64 create a pair of opposed radially
inwardly projecting flanges 66 that prevent the fastener head 52 from being
moved axially when the cutting tool 12 is partially rotated relative to the
sleeve
18. When head 52 is realigned with oblong opening 62, the cutting tool is
removable from the sleeve 18.
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[0042] Sleeve 18 includes an oblong through bore 68 passing through the
cylindrical outer walls perpendicular to the longitudinal axis 69 of the
cylindrical
rod 60. As best shown in FIG. 10, through bore 68 has a generally oval-shaped
cross-sectional shape with its major axis substantially perpendicular to axis
69
with its shorter minor axis aligned with axis 69.
[0043] Referring now to FIGs. 2 and 8-10, tool 10 further includes a
camming pin
20 having a eccentrically shaped elongated body 70 having an outer camming
surface 72. The forward end of the body 70 terminates at a cylindrical support
post 73, while the rearward end terminates at a threaded fastener portion 74.
Post 73 is sized to fit within the untapped end of aperture 37 while threaded
portion 74 is sized to threadably mate with tapped portion 37a.
[0044] Importantly, body 70 is sized to fit within oval bore 68 such that
when
sleeve 18 is inserted within section 30 of the axial bore 22 and camming pin
20 is
passed through oblong bore 68 and support post 73 is received within the
untapped portion 37b of lock-pin aperture 37, and upon rotation of the camming
pin 20 (e.g., tightening pin by rotating the pin clockwise in FIG. 10), the
eccentrically shaped camming surface 72 abuts the upper surface 68a of oblong
bore 68 resulting in the sleeve 18 to move upward in the direction of arrow 76
within axial bore section 30.
[0045] Oblong opening 62 is formed into the bottom of sleeve 18 at a
substantially ninety degree angle about axis 69 relative to through bore 68.
In
this manner, when sleeve 18 is locked within axial bore section 30, the oblong
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opening 62 and the major axis of the oval-shaped drive section 29 are
substantially parallel.
[0046] During assembly, retention sleeve 20 is inserted within support
section 30
with opening 62 facing down toward end 24 of the tool holder. Camming pin 20
is inserted through aperture 37 and bore 68. At this stage of the assembly,
pin
20 is tightened into opening 37a to a point such that the camming body 70 is
remote from upper surface 68a. As best shown in FIG. 5, shank 39 is
telescopically received by axial bore 22. Fastener head 52 is inserted through
the aligned oblong opening 62 and passes into enlarged opening 64; cylindrical
support portion 42 slides into the lower end of support section 30; the oval
driver
portion 41 is received within drive section 29 with the two major axes of the
oval
shapes 30, 41 being substantially parallel; and the tapered portion 40 being
received within complementary tapered section 28.
[0047] As best shown in FIGs. 6 and 7, to increase rigidity of the cutting
tool 12
within tool holder 16, the cutting tool 12 is then partially rotated within
tool holder
until the leading surfaces 45b of the driver wall 45 abut the tool holder's
drive wall
33. This rotation of the cutting tool concomitantly results in lugs 56 of the
retention head 52 to overlap the inwardly projecting flanges 66 of the
retention
sleeve 18. In the preferred embodiment, the oval drive section 28 and driver
portion 41 are sized such that their walls abut after an approximate ninety
degree
relative rotation occurs between the cutting tool 12 and tool holder 16. It
should
be appreciated that to best support the cutting tool 12 during a cutting
operation,
this relative rotation is in the opposite direction of the direction of the
cut such
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that the abutting oval walls 33, 45 support the cutting tool and prevent any
further
rotation of the cutting tool 12 about the now-coaxial axes 34, 46 as a result
of the
cutting edge at end 38 machining a workpiece.
[0048] Once the walls 33, 45 are in abutting engagement, the assembly is
completed by further rotating (e.g., tightening) camming pin 20 such that
camming surface 72 engages upper surface 68a within the retention sleeve 18,
thereby pushing the sleeve 18 further into the section 30, which in turn pulls
the
shank's fastener head 52 such that the cutting tool 12 and tool holder 16
wedge
together at complementary conical surfaces 32, 44, thereby releasably
interlocking the cutting tool to the tool holder.
[0049] It should be appreciated that a cutting tool to tool holder
arrangement
between shank 39 and the axial bore 22 is provided that forms three distinct
interfaces including: mating conical surfaces that are compressed together by
retention sleeve 18, at least one interference-fitting drive walls 33, 45 and
a
cylindrical support shaft 42 that cooperates with a complementary bore 30 to
prevent cutting tool 12 from tilting or canting within tool holder 16.
[0050] While the present invention has been described with particular
reference
to various preferred embodiments, one skilled in the art will recognize from
the
foregoing discussion and accompanying drawing and claims that changes,
modifications and variations can be made in the present invention without
departing from the spirit and scope thereof as defined in the following
claims.
[0051] Having described my invention, I claim:
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