U.S. patent application number 09/850891 was filed with the patent office on 2002-11-14 for cutting tool assembly with replaceable cutting head.
This patent application is currently assigned to Allied Machine & Engineering Corp. Invention is credited to Mast, Wendell E., Nuzzi, Joseph P., Stokey, Timothy G..
Application Number | 20020168239 09/850891 |
Document ID | / |
Family ID | 25309383 |
Filed Date | 2002-11-14 |
United States Patent
Application |
20020168239 |
Kind Code |
A1 |
Mast, Wendell E. ; et
al. |
November 14, 2002 |
CUTTING TOOL ASSEMBLY WITH REPLACEABLE CUTTING HEAD
Abstract
The present invention provides a new cutting tool assembly
comprising a replaceable cutting head and a tool body having a
common longitudinal axis and mating peripheral surfaces. The
cutting head has a cutting portion forming a leading end, a pilot
portion forming a trailing end, and a cutting head mounting portion
adjacent the trailing end of the cutting head. The tool body has a
cutting head receiving portion formed at a leading end of the tool
body and a pilot recess disposed in the leading end of the tool
body to matingly receive the pilot portion of the cutting head. The
cutting head mounting portion and the cutting head receiving
portion of the tool body each have at least two coupling portions.
The cutting head coupling portions and the tool body coupling
portions are bound by their peripheral surfaces and generally mate
in shape and dimensions. Each coupling portion has a pair of base
surfaces, including upper and lower surfaces. The base surfaces
extend transversely to the longitudinal axis and provide support of
the cutting head in the tool body. A torque transmission wall
extends between the upper and lower base surfaces from the pilot
portion surface in a generally transverse direction relative to the
longitudinal axis and oriented transversely to the base surfaces. A
fastener may be disposed in the tool body along its longitudinal
axis where it matingly engages the pilot portion of the cutting
head and exerts an axial force on the cutting head for pressing the
cutting head mounting portion against the cutting head receiving
portion of the tool body.
Inventors: |
Mast, Wendell E.; (Dundee,
OH) ; Stokey, Timothy G.; (Dover, OH) ; Nuzzi,
Joseph P.; (Dover, OH) |
Correspondence
Address: |
HAHN LOESER & PARKS, LLP
TWIN OAKS ESTATE
1225 W. MARKET STREET
AKRON
OH
44313
US
|
Assignee: |
Allied Machine & Engineering
Corp
|
Family ID: |
25309383 |
Appl. No.: |
09/850891 |
Filed: |
May 8, 2001 |
Current U.S.
Class: |
408/144 ;
408/230; 408/233; 408/713 |
Current CPC
Class: |
Y10S 408/713 20130101;
B23B 2260/034 20130101; Y10T 408/78 20150115; Y10T 408/9097
20150115; Y10T 408/03 20150115; Y10T 408/90993 20150115; B23B
2251/02 20130101; B23B 51/02 20130101 |
Class at
Publication: |
408/144 ;
408/230; 408/233; 408/713 |
International
Class: |
B23B 051/02 |
Claims
What is claimed is:
1. A cutting tool assembly comprising: a replaceable cutting head
and a tool body having a common longitudinal axis and mating
peripheral surfaces; said cutting head having a cutting portion
forming a leading end, a pilot portion forming a trailing end, and
a cutting head mounting portion adjacent said pilot of said cutting
head; said tool body having a cutting head receiving portion formed
at a leading end of said tool body and a recess disposed in said
leading end of said tool body to matingly receive said pilot
portion of said cutting head; said cutting head mounting portion
and said cutting head receiving portion of said tool body each
having at least two coupling portions, said cutting head coupling
portions and said tool body coupling portions being bound by said
peripheral surfaces and generally mating in shape and dimensions;
each coupling portion having a pair of surfaces, comprising an
upper and a lower surface, said surfaces extending transversely to
said longitudinal axis and providing support of said cutting head
in said tool body, a torque transmission wall extending between
said upper and lower surfaces from said pilot portion surface to
said peripheral surface in a generally transverse direction
relative to said longitudinal axis and oriented transversely to
said surfaces, a fastener centrally disposed in said tool body
along said longitudinal axis and engaging said pilot portion of
said cutting head and exerting an axial force on said cutting head
for pressing said cutting head mounting portion against said
cutting head receiving portion of said tool body.
2. The cutting tool of claim 1 wherein at least one of said pair of
surfaces is oriented obliquely in relation to a radial plane from
said longitudinal axis.
3. The cutting tool of claim I wherein said pair of surfaces are
oriented obliquely in relation to a radial plane from said
longitudinal axis.
4. The cutting tool of claim 1 wherein at least one of said pair of
surfaces is circumferentially oblique in relation to a radial plane
from said longitudinal axis.
5. The cutting tool of claim 1 wherein said pair of surfaces is
circumferentially oblique in relation to a radial plane from said
longitudinal axis.
6. The cutting tool of claim 1 wherein at least one of said pair of
surfaces is oriented such that a portion of a force acting
longitudinally along said cutting tool is directed at least
partially toward said torque transmission wall to assist in said
retention of said cutting head upon said tool body.
7. The cutting tool of claim 1 wherein said fastener engages a
threaded recess formed in a trailing end of said pilot portion of
said cutting head.
8. The cutting tool of claim 1 wherein said fastener engages a
threaded insert positioned in a recess formed in a trailing end of
said pilot portion of said cutting head.
9. The cutting tool of claim 1 wherein said cutting head is made of
a material selected from the group consisting of hardened carbide,
high speed steel, ceramic, cemented carbide or combinations
thereof.
10. The cutting tool of claim 1 wherein said cutting head is made
by molding of a material into the desired final configuration.
11. The cutting tool of claim 1 wherein said fastener further
comprises a connection member, a spring, a spring retainer plug and
means for applying a preload on said connection member.
12. The cutting tool of claim 11, wherein said means for applying a
preload on said connection member provides a preload which is
greater than the elastic deformation of the tool holder during
operation of the cutting tool.
13. The cutting tool of claim 11 wherein the cutting head is
removable from the connection member by rotation of the cutting
head to a position that it is sufficiently disengaged such that the
cutting head mounting portion of the cutting head and cutting head
receiving portion of the tool body do not interfere with each
other, and disengaging the cutting head from the connection
member.
14. The cutting tool of claim 11, wherein the cutting head is
replaceable with the tool body positioned operatively in a tool
holder for performing a cutting operation, wherein the pilot
portion is axially aligned with the tool body such that the pilot
portion is directly over a leading end of the connection member,
and wherein the cutting head is rotatable into engagement with the
connection member until the mounting portion of the cutting head
and cutting head receiving portion of the tool body approach each
other and such that the mounting portion of the cutting head and
cutting head receiving portion of the tool body are generally
aligned, wherein the cutting head is then rotatable such that said
torque transmission walls of the at least two coupling portions
register against one another.
15. The cutting tool of claim 14, wherein the means for applying a
preload on said connection member is operated once the torque
transmission walls of the at least two coupling portions register
against one another.
16. A method of mounting and replacing a replaceable cutting head
of a cutting tool assembly comprising the steps of: 1) providing a
cutting tool having a replaceable cutting head and a tool body
having a common longitudinal axis and mating peripheral surfaces,
said cutting head having a cutting portion forming a leading end, a
pilot portion forming a trailing end, and a cutting head mounting
portion, and said tool body having a cutting head receiving portion
formed at a leading end of said tool body and a recess disposed in
said leading end of said tool body to matingly receive said pilot
portion of said cutting head, wherein said cutting head mounting
portion and said cutting head receiving portion of said tool body
each having at least two coupling portions, each coupling portion
having a pair of surfaces extending transversely to the
longitudinal axis of the cutting tool and providing support of said
cutting head with said tool body and having a torque transmission
wall extending between said pair of surfaces in a generally
transverse direction relative to said longitudinal axis and
oriented transversely to said surfaces, and a fastener centrally
disposed in said tool body along said longitudinal axis, 2) axially
aligning the pilot portion with the tool body such that the pilot
portion is directly over a leading end of the fastener, 3) engaging
said pilot portion of said cutting head with said fastener, 4)
rotating the cutting head into engagement with the fastener until
the mounting portion of the cutting head and cutting head receiving
portion of the tool body approach each other and such that the
mounting portion of the cutting head and cutting head receiving
portion of the tool body are generally aligned, 5) rotating the
cutting head further such that said torque transmission walls of
the at least two coupling portions register against one another,
and 6) using the fastener to exert an axial force on said cutting
head for pressing said cutting head mounting portion against said
cutting head receiving portion of said tool body, whereby the
cutting head is replaceable by providing a replacement cutting head
and repeating steps 2 through 6 while the tool body is positioned
in a tool holder associated with a cutting operation.
Description
TECHNICAL FIELD
[0001] The present invention relates to a cutting tool assembly for
rotary cutting and/or machining, comprising a tool body and a
replaceable cutting head. More particularly, the present invention
relates to a cutting tool having a replaceable cutting head
retained on a tool body by a retaining system, wherein the cutting
head comprises a unique mating surface configuration enabling an
increased retention force on the cutting head while providing
optimized torque transferability.
BACKGROUND OF THE INVENTION
[0002] It is previously known to provide rotary cutting tools, such
as drills, with replaceable cutting heads or drill tips. These tips
have been retained on a tool body by many methods including radial
set screws secured through lands provided on the tool body, press
fit connections using dove-tail profiles, axial screws and
drawbars, etc. While each method has different advantages and
disadvantages, none of these tools can be easily and quickly
replaced while maintaining optimized torque transferability, high
feed rates, and a secure mounting to the tool body. Some prior
tools of this type have worked well but have not been generally
usable in aggressive machining operations, which produce high
stress on the connection of the cutting head to the tool body.
[0003] Several examples of prior art configurations use a dovetail
profile to connect the cutting head to the tool body. The cutting
head is inserted into a recess generally having at least one radial
base surface. The cutting head is then rotated such that a dovetail
profile on the cutting head engages a dovetail recess of the tool
body. This engagement is typically an interference fit type
arrangement such that the cutting head is prevented from rotating
in a disengaging direction. In order for the interference fit to
provide sufficient retaining force, high stresses result at the
tool body interface with the cutting head and in some cases, a
special tool is needed to connect and disconnect the cutting head.
Another problem with such a connection is that the feed force
during operation of the tool pushes the cutting head downward into
the tool body, which can lessen the retaining force of the dovetail
connection and permit the cutting head to loosen.
[0004] Other examples of connecting the cutting head use an axial
engagement bar to secure the cutting head to the tool body.
Although attempting to clamp the head to the body, the high stress
at the interface again may result in loosening of the connection
and/or make the tool susceptible to eccentric and other loads.
[0005] It is also found in various tools with replaceable cutting
heads, that it may be impossible to change the cutting head while
the tool is mounted in an associated tool holder or machine. Thus,
it is required that the entire tool be removed from the tool holder
or machine, the cutting head then being replaced, and the tool
being reintroduced into the machine for continued operation. Such a
process adds labor and time, and detracts from the advantages of
having the replaceable insert, and from the machining speeds
achievable.
[0006] Accordingly, there remains a need in the art for a new drill
assembly utilizing a replaceable cutting head which combines the
advantages of a replaceable cutting head with the ability to be
used in aggressive machining operations in which high stress
conditions will exist. There also remains a need to provide drill
assembly utilizing a replaceable cutting head which allows the
cutting head to be replaced while the tool is mounted in the tool
holder or machine to simplify and speed up this process.
SUMMARY OF THE INVENTION
[0007] It is therefore an object of the present invention to
provide a new cutting tool assembly comprising a replaceable
cutting head and a tool body having a common longitudinal axis and
mating peripheral surfaces. The cutting head has a cutting portion
forming a leading end, a pilot portion forming a trailing end, and
a cutting head mounting portion adjacent the trailing end of the
cutting head. The tool body has a cutting head receiving portion
formed at a leading end of the tool body and a pilot recess
disposed in the leading end of the tool body to matingly receive
the pilot portion of the cutting head. The cutting head mounting
portion and the cutting head receiving portion of the tool body
each have at least two coupling portions. The cutting head coupling
portions and the tool body coupling portions are bound by their
peripheral surfaces and generally mate in shape and dimensions.
Each coupling portion has a pair of base surfaces, including upper
and lower surfaces. The base surfaces extend transversely to the
longitudinal axis and provide support of the cutting head in the
tool body. A torque transmission wall extends between the upper and
lower base surfaces from the pilot portion surface in a generally
transverse direction relative to the longitudinal axis and oriented
transversely to the base surfaces. A fastener may be disposed in
the tool body along its longitudinal axis where it matingly engages
the pilot portion of the cutting head and exerts an axial force on
the cutting head for pressing the cutting head mounting portion
against the cutting head receiving portion of the tool body.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is an exploded perspective view of the cutting tool
assembly of the present invention along its longitudinal axis
A;
[0009] FIG. 2 is a perspective view of the cutting head and leading
end of the tool body in accordance with the present invention of
FIG. 1;
[0010] FIG. 3 is a perspective view of the cutting head which is
inclined along longitudinal axis A revealing the pilot portion at
the trailing end of cutting head and the cutting head mounting
portion in accordance with the present invention of FIG. 1;
[0011] FIG. 4 is an end view of the trailing end of the cutting
head in accordance with the present invention of FIG. 1;
[0012] FIG. 5 is a perspective view of the leading end of the tool
body which is inclined along longitudinal axis A revealing the tool
body coupling portions on opposite sides of the recess in
accordance with the present invention of FIG. 1;
[0013] FIG. 6 is an end view of the leading end of the tool body in
accordance with the present invention of FIG. 1;
[0014] FIG. 7 is a perspective view of the cutting head mounted on
the leading end of the tool body in accordance with the present
invention of FIG. 1;
[0015] FIG. 8 is a cross-sectional view of the cutting tool
assembly in an assembled state taken along longitudinal axis A;
[0016] FIG. 9 is an exploded perspective view of an alternate
embodiment of the present invention which includes a cutting head
assembly comprising a cutting head shown inclined along
longitudinal axis A and a threaded insert which is matingly
attached within the threaded recess of the cylindrical pilot
portion; and
[0017] FIG. 10 is a cross-sectional view of the cutting head
assembly of FIG. 9 in an assembled state showing the threaded
insert matingly attached within the recess in the cylindrical pilot
portion.
DETAILED DESCRIPTION
[0018] Referring now to the drawings, wherein similar reference
characters designate corresponding parts throughout the several
views, there is generally indicated at 10 a cutting tool assembly
according to the present invention, for use in drilling operations.
Referring now to FIG. 1, cutting tool assembly 10 having a
longitudinal axis A, comprises a replaceable cutting head 12, a
tool body 14 formed on a tool shank 16, and a fastening assembly 18
to facilitate retention of the cutting head 12 on tool body 14. The
cutting head 12 and the tool body 14 are formed with chip flute
sections 20, and 22, respectively, that, when the cutting tool is
assembled, form continuous, preferably helical, flutes 24 which
extend from the cutting head 12 to the trailing end 26 of the tool
body 14.
[0019] As illustrated in FIGS. 2-4, the cutting head 12 has a
cutting portion 28 formed on a leading end 30 of the cutting head
12, a generally cylindrical pilot portion 32 forming a trailing end
34 of the cutting head 12, and a cutting head mounting portion 36
adjacent the pilot 32 of the cutting head 12. The cutting portion
28 of the cutting head 12 will not be described herein since it
does not constitute the subject matter of the present invention.
However, it should be noted that the cutting portion 28 of the
cutting head 12 may have any appropriate design for the intended
machining operation to be performed. The cutting head mounting
portion 36 comprises a pair of diametrically disposed cutting head
coupling portions 40 each bound by a land, or peripheral surface 38
and the chip flutes 20 and separated from each other diametrically
by cylindrical pilot portion 32. Each cutting head coupling portion
40 has a single-step configuration with a lower base surface 42
adjacent one chip flute section 20, an upper base surface 44
adjacent the other chip flute section 20 and a torque transmission
wall 46 therebetween, which all extend from the peripheral surface
38 of the cutting head mounting portion 36 transversely inward
towards cylindrical pilot portion 32. The lower base surface 42,
upper base surface 44, and torque transmission wall 46 may extend
either perpendicularly or at an angular orientation with axis A
between peripheral surface 38 and pilot portion 32. A pair of
diametrically opposed flush channels 56 extend longitudinally from
upper base surface 44 toward leading end 30 of cutting head 12. The
flush channels 56 enable high pressure coolant to be delivered in
close proximity to the cutting surfaces to effectively remove
generated chips and heat from the cutting area.
[0020] The lower base surface 42 and the upper base surface 44 of
the cutting head 12 are oriented transversely to longitudinal axis
A and obliquely to a radial plane through longitudinal axis A.
Lower base surface 42 and upper base surface 44 are oriented
obliquely inward in the radial direction and directed toward the
trailing end 34 of the cutting head. Lower base surface 42 and
upper base surface 44 may each be planar or formed as a curved
surface, such as in a generally helical shape. Lower base surface
42 is oriented at an angle toward torque transmission wall 46 such
that a first end 48 of the lower base surface 42, which mates with
torque transmission wall 46, is lower with respect to leading end
30 than a second end 50 of lower base surface 42, which terminates
at flute 20. Torque transmission wall 46 may be oriented at an
acute angle with respect to lower base surface 42. Upper base
surface 44 of the cutting head 12 may be oriented at a reverse
angle from torque transmission wall 46 such that a first end 52 of
the upper base surface 44 which mates with torque transmission wall
46 is lower with respect to the leading end 30 than a second end 54
of upper base surface 44. Torque transmission wall 46 may be
oriented at an acute angle with respect to upper base surface 44.
Upper base surface 44, torque transmission wall 46, and lower base
surface 42 form a "sawtooth" engagement such that none of the base
surfaces, 42, 44, are in a radial plane from longitudinal axis A
and torque transmission wall 46 is oriented at an acute angle to
both base surfaces 42, 44.
[0021] Referring now to FIGS. 2, and 5-6, tool body 14 has a
cutting head receiving portion 60 formed on the leading end 58 of
the tool body 14. Cutting head receiving portion 60 is formed to
matingly engage cutting head mounting portion 36 and cylindrical
pilot portion 32 of cutting head 12. Referring again to FIG. 2, the
cutting head receiving portion 60 comprises a pair of diametrically
disposed tool body coupling portions 80 each radially bound by a
land, or peripheral surface 78 and chip flutes 22. Each cutting
head receiving portion 60 has a single-step configuration with a
lower base surface 62 adjacent one chip flute section 22, an upper
base surface 64 adjacent the other chip flute section 22 and a
torque transmission wall 66 therebetween, which all extend from the
peripheral surface 78 of the cutting head receiving portion 60,
generally transversely inward towards a cylindrical recess 84
formed between coupling portions 80.
[0022] Lower support surface 62 and upper support surface 64 of the
tool body 14 are both oriented transversely to longitudinal axis A
and obliquely to a radial plane through longitudinal axis A. Lower
support surface 62 and upper support surface 64 are oriented
obliquely inward in the transverse direction and directed toward
tool shank 16. Lower support surface 62 and upper support surface
64 may be planar or formed as a curved surface, such as in a
generally helical shape. Lower support surface 62 is oriented at an
angle toward torque transmission wall 66 such that a first end 68
of the lower support surface 62 which mates with torque
transmission wall 66 is lower with respect to a second end 70 of
lower support surface 62 which terminates at flute 22. Torque
transmission wall 66 is oriented at an acute angle with respect to
lower support surface 62. Upper support surface 64 of the tool body
14 is oriented at a reverse angle from torque transmission wall 66
such that a first end 72 of upper support surface 64 which mates
with torque transmission wall 66 is lower with respect to a second
end 74 of upper support surface 64 which terminates at flute 22 and
surface 76 which forms a transition portion from the tool body 14
to the cutting head 12. As with the cutting head, torque
transmission wall 66 is oriented at an acute angle with respect to
upper support 10 surface 64. Upper support surface 64, torque
transmission wall 66, and lower support surface 62 form a
"sawtooth" engagement such that none of the support surfaces, 62,
64, are in a radial plane and torque transmission wall 66 is
oriented at an acute angle to both support surfaces 62, 64 of tool
body 14.
[0023] Cutting head 12 matingly engages tool body 14 as best shown
in FIG. 7. The sawtooth engagement of the cutting head 12 on tool
body 14 assists in retaining cutting head 12 on tool body 14. The
angled engagement surfaces enable both torsional forces and axial
forces imposed on the tool 10 in operation, to assist in securing
the cutting head 12 on tool body 14. Torsional forces are
transmitted directly from torque transmission wall 46 of cutting
head 12 to torque transmission wall 66 of tool body 14. The
opposing angled surfaces of torque transmission walls 46, 66 act to
draw the cutting head 12 toward tool body 14 in operation. In a
similar fashion, lower base and support surfaces 44, 64 are also
angled relative to one another and the torque transmission walls
46, 66 such that a portion of axial feed forces on cutting tool
assembly 10 assists in drawing torque transmission wall 46 of
cutting head 12 to torque transmission wall 66 of tool body 14
resulting in the additional retention force through the sawtooth
engagement. In addition, the angled surfaces of the sawtooth
engagement help ensure that cutting head 12 is properly aligned on
tool body 14 during assembly.
[0024] Referring now to FIG. 8, a cross-sectional view of the
assembled cutting tool assembly is shown. A fastener assembly 18
facilitates retention of the cutting head 12 on tool body 14.
Fastener assembly 18 comprises a connection member 90, a spring 92,
and a spring retainer plug 94. In operation, connection member 90
is inserted into a corresponding cylindrical cavity 98 along the
longitudinal axis A of tool body 14. Spring 92 is then inserted
into axial cavity 98 through an opening at the trailing end 96 of
tool shank 16 and retained in the cavity 98 by spring retainer plug
94. Spring retainer plug 94 threadably engages the walls of cavity
98 such that spring 92 biases connection member 90 toward the
leading end of the tool body 14. Connection member 90 comprises a
threaded portion 108 on a leading end of the connection member 90,
which matingly engages a threaded recess 100 within cylindrical
pilot portion 32 of cutting head 12. The connection member 90 is
drawn backwards towards a trailing end 96 of tool shank 16 by an
adjusting mechanism 102. Adjusting mechanism 102 may comprise a set
screw, which is adjustable in a direction transverse to
longitudinal axis A within an aperture 104 in tool shank 16 which
extends through from the perimeter of the tool shank 16 to cavity
98. Set screw 102 engages an angled mating surface 106 in
connection member 90 thereby drawing connection member 90 towards
the trailing end 96 of tool shank 16 and securing cutting head 12
thereon. Set screw 102 is adjusted to provide sufficient tension on
connection member 90 to obtain a predetermined preload. In general,
the preload on the connection member should be greater than the
elastic deformation of the tool holder 14 and shank 16. This will
help ensure that a cutting head 12 is retained on the tool body
14.
[0025] Drill assembly 10 is intended to be used such that the
cutting head 12 can be replaced while the tool shank 16 remains in
the tool holder (not shown). The method of replacing cutting head
12 comprises the steps of first loosening set screw 102 such that
connection member 90 moves longitudinally toward the leading end of
tool body 14 under the biasing force of spring 92. The cutting head
12 is either pushed away from the tool body mating surface or is
rotated slightly to disengage the sawtooth engagement and allow
cutting head 12 to move longitudinally under the bias force of
spring 92. Once the set screw 102 has been loosened to a
predetermined position, the cutting head 12 is removed from the
leading end 108 of connection member 90 by rotating cutting head
12. Once cutting head 12 is sufficiently disengaged such that the
cutting head mounting portion 36 of cutting head 12 and cutting
head receiving portion 60 of tool body 14 do not interfere with
each other, the cutting head 12 is disengaged from connection
member 90. To install the replacement cutting head 12 while the
tool shank 16 remains in the tool holder, the opposite procedure is
used. The pilot portion 32 is axially aligned with the recess 84 in
a manner that the insert 12 is axially aligned with the tool body
14. The cutting head 12 is aligned such that the threaded recess
100 in cylindrical pilot portion 32 is directly over the leading
end 108 of connection member 90. The cutting head 12 is then
rotated in the appropriate direction until the base and support
surfaces 42, 64 of the cutting head 12 and tool body 14 approach
each other. The cutting head 12 is generally aligned such that the
base surfaces 42, 44 of cutting head 12 and support surfaces 62, 64
of tool body 14, respectively, are aligned, and the cutting head 12
is then rotated as the head 12 is drawn toward the support surfaces
62, 64 until matingly engaged. The cutting head 12 is then rotated
slightly such that torque transfer walls 46 of cutting head 12
register against torque transfer walls 66 of tool body 14. While
the cutting head is in position, set screw 102 is then rotated in
an appropriate direction such that connection member 90 is moved
longitudinally toward the trailing end 96 of tool shank 16 until a
predetermined amount of retention force is applied on cutting head
12 against tool body 14 to provide a preload on connection member
90. As previously mentioned, the retention force is generally
sufficient such that the preload on the connection member is
greater than the elastic deformation of the tool holder 14 and
shank 16. This will help ensure that a cutting head 12 is retained
on the tool body 14.
[0026] Turning to FIGS. 9 and 10, cutting head 12 is typically made
of a hard material, such as hardened carbide, high-speed steel,
ceramic material or any other suitable material. In an alternate
embodiment, cutting head 12' further comprises a thread insert 110
which is inserted into threaded recess 100 on the cylindrical pilot
portion 32 of cutting head 12. Thread insert 110 is used to protect
the threads of connection member 90 from being worn down by the
threads of tool material of the cutting head 12 while different
cutting heads 12 are being repeatedly removed and replaced. The
thread insert 110, being of larger diameter, will provide
additional strength in the connection with cutting head 12, and
will more accurately engage the retention assembly 18.
[0027] It should be recognized from the foregoing that the present
invention provides distinct advantages in the use of a replaceable
cutting head, while allowing operation in aggressive machining
environments. The configuration of the connection between the
cutting head 12 and tool body 14 provides an assembled tool which
performs substantially as a unitary construction, while providing
the benefits of a replaceable cutting head. In the preferred form,
the base surfaces 42, 44 and support surfaces 62, 64 are configured
such that the mating relationship between the surfaces is angled
inwardly so feed thrust will force the insert toward the torque
transmission wall to more firmly secure the cutting head 12 on the
tool body 14. Further, the sawtooth connection of the preferred
form provides a forward directed leading edge which creates a
downward axial force vector which forces the cutting head 12
against the support surfaces 62, 64, also resulting in a more
secure connection. The combination of these structures work
synergistically to provide a connection which effectively removes
any relative movement between the cutting head 12 and tool body 14,
resulting in an assembled tool which performs in the desired
manner.
[0028] Although the present invention has been described above in
detail, the same is by way of illustration and example only and is
not to be taken as a limitation on the present invention.
Accordingly, the scope and content of the present invention are to
be defined only by the terms of the appended claims.
* * * * *