U.S. patent application number 15/586647 was filed with the patent office on 2018-11-08 for rotary cutting tool having axially supported lead cutting insert and a continuous cutting edge.
This patent application is currently assigned to Ingersoll Cutting Tool Company. The applicant listed for this patent is Ingersoll Cutting Tool Company. Invention is credited to William B. JOHNSON, Eric William NGUYEN, Dennis Etienne ROEPSCH.
Application Number | 20180318944 15/586647 |
Document ID | / |
Family ID | 62196651 |
Filed Date | 2018-11-08 |
United States Patent
Application |
20180318944 |
Kind Code |
A1 |
NGUYEN; Eric William ; et
al. |
November 8, 2018 |
ROTARY CUTTING TOOL HAVING AXIALLY SUPPORTED LEAD CUTTING INSERT
AND A CONTINUOUS CUTTING EDGE
Abstract
A rotary cutting tool has a cutting body and a plurality of
cutting inserts, including a first insert removably secured in a
first pocket and a second insert removably secured in a second
pocket. The first pocket opens out at a forward end surface of the
cutting body, having a seat surface with an axial support wall
transverse thereto, and the second pocket is located axially
rearward of the first pocket. The first insert has opposing front
and back end surfaces, with a peripheral side surface extending
therebetween which is in contact with the seat surface and the
axial support wall. A first major cutting edge of the first insert
axially overlaps with a second major cutting edge of the second
insert, and in a side view of the cutting tool, a raised shoulder
surface adjacent the axial support wall is at least partially
obscured by the second insert.
Inventors: |
NGUYEN; Eric William; (South
Beloit, IL) ; JOHNSON; William B.; (Machesney Park,
IL) ; ROEPSCH; Dennis Etienne; (Cherry Valley,
IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ingersoll Cutting Tool Company |
Rockford |
IL |
US |
|
|
Assignee: |
Ingersoll Cutting Tool
Company
Rockford
IL
|
Family ID: |
62196651 |
Appl. No.: |
15/586647 |
Filed: |
May 4, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B23C 2200/0416 20130101;
B23C 2210/168 20130101; B23C 5/006 20130101; B23C 5/109 20130101;
B23C 2200/0433 20130101; B23C 5/20 20130101; B23C 5/207 20130101;
B23C 2200/367 20130101 |
International
Class: |
B23C 5/24 20060101
B23C005/24 |
Claims
1. A cutting tool (20) rotatable about a tool axis (AT) defining a
forward-rearward direction (D.sub.F, D.sub.R) and having a
direction of rotation (R), the cutting tool (20) comprising: a
cutting body (22) having: a forward end surface (32); a first
insert receiving pocket (28) opening out to the forward end surface
(32) and having a first insert seat surface (56) with a first
insert axial support wall (58) transverse thereto; a second insert
receiving pocket (30) located axially rearward of the first insert
receiving pocket (28) and having a second insert seat surface (62);
and a raised shoulder surface (84) adjacent the first insert axial
support wall (58); a first cutting insert (24) removably secured in
the first insert receiving pocket (28), the first cutting insert
(24) having opposing first insert front and back end surfaces (36,
38) with a first insert peripheral side surface (40) extending
therebetween and a first insert axis (A1) extending therethrough,
and at least one first insert front major cutting edge (42) formed
at the intersection of the first insert front end surface (36) and
the first insert peripheral side surface (40), and a second cutting
insert (26) removably secured in the second insert receiving pocket
(30), the second cutting insert (26) having opposing second insert
front and back end surfaces (46, 48) with a second insert
peripheral side surface (50) extending therebetween and a second
insert axis (A2) extending therethrough, and at least one second
insert front major cutting edge (52) formed at the intersection of
the second insert front end surface (46) and the second insert
peripheral side surface (50), wherein: the first insert seat
surface (56) contacts a first portion of the first insert
peripheral side surface (40), the first insert axial support wall
(58) contacts a second portion of the first insert peripheral side
surface (40), one of the at least one first insert front major
cutting edge (42) is operative and one of the at least one second
insert front major cutting edge (52) is operative, a second tool
plane (PT2) perpendicular to the tool axis (AT) intersects the
operative first insert front major cutting edge (42) and the
operative second insert front major cutting edge (52), and in a
side view of the cutting tool (20) perpendicular to the tool axis
(AT), the raised shoulder surface (84) is at least partially
obscured by the second cutting insert (26).
2. The cutting tool (20) according to claim 1, wherein: the first
insert receiving pocket (28) includes a first insert tangential
support wall (86) transverse to the first insert seat surface (56),
and the first insert tangential support wall (86) contacts the
first insert back end surface (38).
3. The cutting tool (20) according to claim 2, wherein: in a side
view of the cutting body (22), the first insert axial and first
insert tangential support walls (58, 86) form an external acute
second pocket angle (.alpha.2).
4. The cutting tool (20) according to claim 2, wherein in a
cross-section taken in a third tool plane (PT3) perpendicular to
the tool axis (AT) and intersecting the first insert seat surface
(56) and the first insert tangential support wall (86), the first
insert seat surface (56) and the first insert tangential support
wall (86) form an external acute third pocket angle (.alpha.3).
5. The cutting tool (20) according to claim 2, wherein: the first
insert tangential support wall (86) faces the direction of rotation
(R).
6. The cutting tool (20) according to claim 5, wherein: a
tangential end wall (94) contiguous with the shoulder surface (84)
faces the direction of rotation (R), and the tangential end wall
(94) is located rotationally forward of the first insert tangential
support wall (86).
7. The cutting tool (20) according to claim 2, wherein: the cutting
body (22) has a cylindrical outer peripheral surface (96) extending
axially rearwardly from the forward end surface (32), and the first
insert tangential support wall (86) intersects the outer peripheral
surface (96).
8. The cutting tool (20) according to claim 7, wherein: the first
insert back end surface (38) has a pair of first back abutment
surfaces (98a, 98b), and only one of the two first back abutment
surfaces (98a, 98b) is in contact with the first insert tangential
support wall (86), with contact occurring at the radially outermost
portion of the first insert tangential support wall (86).
9. The cutting tool (20) according to claim 8, wherein in a
cross-section taken in a first insert major plane (PM1) containing
the first insert axis (A1), the first insert back end surface (38)
has a convex shape.
10. The cutting tool (20) according to claim 9, wherein in the
cross-section taken in the first insert major plane (PM1), the pair
of first insert back abutment surfaces (98a, 98b) form an internal
obtuse first insert angle (.alpha.1).
11. The cutting tool (20) according to claim 1, wherein: the first
insert peripheral side surface (40) includes two opposing first
insert major side surfaces (66a, 66b) and two opposing first minor
side surfaces (68a, 68b), one of the two first insert major side
surfaces (66a, 66b) is in contact with the first insert seat
surface (56), and one of the two first insert minor side surfaces
(68a, 68b) is in contact with the first insert axial support wall
(58).
12. The cutting tool (20) according to claim 11, wherein: the first
cutting insert (24) has a first insert minimum length (L1.sub.MIN)
measured as the shortest distance between the two first minor side
surfaces (68a, 68b), and a first insert maximum width (W1.sub.MAX)
between the two first insert major side surfaces (66a, 66b)
measured perpendicular to the first insert axis (A1) and the first
insert minimum length (W1.sub.MIN), and the first insert minimum
length (L1.sub.MIN) is greater than the first insert maximum width
(W1.sub.MAX).
13. The cutting tool (20) according to claim 12, wherein a first
insert through bore (70) extends between and opens out to the two
first insert major side surfaces (66a, 66b).
14. The cutting tool (20) according to claim 13, wherein a first
clamping screw (72) extends through the first insert through bore
(70) and threadingly engages a first screw bore (74) in the first
insert seat surface (56).
15. The cutting tool (20) according to claim 14, wherein: the first
clamping screw (72) has a first head portion (90) and a first shank
portion (92) extending therefrom, and the first head portion (90)
is entirely located radially outward of the shoulder surface
(84).
16. The cutting tool (20) according to claim 12, wherein: the
second insert peripheral side surface (50) includes two opposing
second insert major side surfaces (76a, 76b) and two opposing
second insert minor side surfaces (78a, 78b), and one of the two
second insert major side surfaces (76a, 76b) is in contact with the
shoulder surface (84).
17. The cutting tool (20) according to claim 16, wherein: the
second cutting insert (26) has a second insert minimum length
(L2.sub.MIN) measured as the shortest distance between the two
second minor side surfaces (78a, 78b), and a second insert maximum
width (W2.sub.MAX) between the two second insert major side
surfaces (76a, 76b) measured perpendicular to the second insert
axis (A2) and the second insert minimum length (L2.sub.MIN), and
the second insert minimum length (L2.sub.MIN) is greater than the
second insert maximum width (W2.sub.MAX).
18. The cutting tool (20) according to claim 17, wherein the first
insert maximum width (W1.sub.MAX) is greater than the second insert
maximum width (W2.sub.MAX).
19. The cutting tool (20) according to claim 1, wherein the second
insert receiving pocket (30) has a second insert tangential support
wall (64) transverse to the second insert seat surface (62).
20. The cutting tool (20) according to claim 19, wherein the
shoulder surface (84) forms a portion of the second insert seat
surface (62).
21. The cutting tool (20) according to claim 19, wherein the entire
second insert seat surface (62) is located radially outward of the
first insert seat surface (56).
22. The cutting tool (20) according to claim 1, wherein a first
tool plane (PT1) containing the tool axis (AT) intersects the first
and second cutting inserts (24, 26).
23. The cutting tool (20) according to claim 22, wherein the first
tool plane (PT1) intersects the shoulder surface (84) and the first
insert peripheral side surface (40).
24. The cutting tool (20) according to claim 22, wherein in a
cross-section taken in the first tool plane (PT1), the shoulder
surface (84) and the first insert axial support wall (58) form an
internal first pocket angle (.alpha.1).
25. The cutting tool (20) according to claim 1, wherein the
shoulder surface (84) is contiguous with the first insert axial
support wall (58).
26. The cutting tool (20) according to claim 1, wherein the second
tool plane (PT2) intersects the shoulder surface (84).
27. The cutting tool (20) according to claim 1, wherein the first
insert axial support wall (58) is located radially outward of the
first insert seat surface (56).
28. The cutting tool (20) according to claim 1, wherein the
shoulder surface (84) is spaced apart from the first insert seat
surface (56) by the first insert axial support wall (58).
29. The cutting tool (20) according to claim 1, wherein the
shoulder surface (84) is located radially outward of the first
insert seat surface (56).
30. The cutting tool (20) according to claim 1, wherein the first
insert peripheral side surface (40) is in contact with the entire
first insert axial support wall (58).
31. The cutting tool (20) according to claim 1, wherein: the first
insert axis (A1) intersects the first insert front and back end
surfaces (36, 38) at front and back end points (N1, N2),
respectively, a first insert median plane (M) perpendicular to the
first insert axis (A1) is located midway between the front and back
end points (N1, N2), and the first insert median plane (M)
intersects the first insert axial support wall (58) and the second
cutting insert (26).
32. The cutting tool (20) according to claim 1, wherein: in the
side view of the cutting tool (20), no portion of the shoulder
surface (84) is obscured by the first cutting insert (24).
33. The cutting tool (20) according to claim 1, wherein: the first
insert peripheral side surface (40) includes two opposing first
insert major side surfaces (66a, 66b) and two opposing first minor
side surfaces (68a, 68b), the first cutting insert (24) has a first
insert maximum width (W1.sub.MAX) defined between the two first
insert major side surfaces (66a, 66b), the first insert axial
support wall (58) has an axial support wall minimum height
(HA.sub.MIN) above the first insert seat surface (56), and the
axial support wall minimum height (HA.sub.MIN) is no less than 15%
of the first insert maximum width (W1.sub.MAX).
34. The cutting tool (20) according to claim 33, wherein: the first
insert receiving pocket (28) includes a first insert tangential
support wall (86) transverse to the first insert seat surface (56),
a tangential end wall (94) contiguous with the shoulder surface
(84) faces in the direction of rotation (R) and is located
rotationally forward of the first insert tangential support wall
(86), and a height of the first insert axial support wall (58)
above the first insert seat surface (56) increases in the direction
of rotation (R) from the first insert tangential support wall (86)
to the tangential end wall (94).
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a rotary cutting tool with
a plurality of cutting inserts providing a continuous effective
cutting edge along a single chip flute, for use in metal cutting
processes in general, and for milling operations in particular.
BACKGROUND OF THE INVENTION
[0002] Within the field of rotary cutting tools used in milling
operations, there are many examples of a plurality of cutting
inserts arranged along a single chip flute to provide a continuous
effective cutting edge.
[0003] U.S. Pat. No. 4,790,693 discloses a milling tool with a
plurality of identical indexable side station inserts in an
inter-fitting arrangement along a single chip gullet, and a single
non-indexable end ("first" or "lead") station insert having a
cutting edge which axially overlaps with the operative cutting edge
of the adjacent side station insert.
[0004] U.S. Pat. No. 8,696,257 discloses a milling tool with a
plurality of identical side and end station inserts arranged along
a single chip removing flute, each insert indexable about a center
line extending through its rake surface and V-shaped seating
surface.
[0005] It is an object of the present invention to provide an
improved milling tool.
[0006] It is also an object of the present invention to provide an
improved milling tool having a plurality of indexable cutting
inserts arranged along a single chip flute.
[0007] It is a further object of the present invention to provide
an improved milling tool in which the end station insert is
removably secured in an end station pocket with a high level of
stability.
SUMMARY OF THE INVENTION
[0008] In accordance with the present invention, there is provided
a cutting tool rotatable about a tool axis defining a
forward-rearward direction and having a direction of rotation, the
cutting tool comprising:
[0009] a cutting body having; [0010] a forward end surface; [0011]
a first insert receiving pocket opening out at the forward end
surface and having a first insert seat surface with a first insert
axial support wall transverse thereto, [0012] a second insert
receiving pocket located axially rearward of the first insert
receiving pocket and having a second insert seat surface; and
[0013] a raised shoulder surface adjacent the first insert axial
support wall; [0014] a first cutting insert removably secured in a
first insert receiving pocket, the first cutting insert having
opposing first insert front and back end surfaces with a first
insert peripheral side surface extending therebetween and a first
insert axis extending therethrough, and at least one first insert
front major cutting edge formed at the intersection of the first
insert front end surface and the first insert peripheral side
surface, [0015] a second cutting insert removably secured in a
second insert receiving pocket the second cutting insert having
opposing second insert front and back end surfaces with a second
insert peripheral side surface extending therebetween and a second
insert axis extending therethrough, and at least one second insert
front major cutting edge formed at the intersection of the second
insert front end surface and the second insert peripheral side
surface,
[0016] wherein:
[0017] the first insert seat surface contacts a first portion of
the first insert peripheral side surface,
[0018] the first insert axial support wall contacts a second
portion of the first insert peripheral side surface,
[0019] one of the at least one first insert front major cutting
edge is operative and one of the at least one second insert front
major cutting edge is operative,
[0020] a second tool plane perpendicular to the tool axis
intersects the operative first insert front major cutting edge and
the operative second insert front major cutting edge, and
[0021] in a side view of the cutting tool perpendicular to the tool
axis, the raised shoulder surface is at least partially obscured by
the second cutting insert.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] For a better understanding, the invention will now be
described, by way of example only, with reference to the
accompanying drawings in which chain-dash lines represent cut-off
boundaries for partial views of a member and in which:
[0023] FIG. 1 is a perspective view of a cutting tool in accordance
with some embodiments of the present invention;
[0024] FIG. 2 is a side view of the cutting tool shown in FIG.
1;
[0025] FIG. 3 is a detailed exploded view of the cutting tool shown
in FIG. 1;
[0026] FIG. 4 is a detailed side view of the cutting tool shown
FIG. 2;
[0027] FIG. 5 is a detailed side view of the cutting tool, taken
perpendicular a first insert seat surface of a first insert
receiving pocket, with the associated first cutting insert and its
first clamping screw removed;
[0028] FIG. 6 is an end view of the cutting tool shown in FIG.
5;
[0029] FIG. 7 is a cross-sectional view of the cutting tool shown
in FIG. 4, taken along the line VII-VII;
[0030] FIG. 8 is a cross-sectional view of the cutting tool shown
in FIG. 4, taken along the line VIII-VIII;
[0031] FIG. 9 is a major side view of the first cutting insert;
[0032] FIG. 10 is a minor side view of the first cutting
insert;
[0033] FIG. 11 is a rear end view of the first cutting insert;
[0034] FIG. 12 is a cross-sectional view of the first cutting
insert shown in FIG. 11, taken along the line XII-XII;
[0035] FIG. 13 is a major side view of the second cutting insert;
and
[0036] FIG. 14 is a minor side view of the second cutting
insert.
DETAILED DESCRIPTION OF THE INVENTION
[0037] As shown in FIGS. 1 to 8, the present invention relates to a
cutting tool 20 rotatable about a tool axis AT, having a cutting
body 22 and a plurality of cutting inserts 24, 26 including a
first, or "lead" cutting insert 24 removably secured in a first
insert receiving pocket 28 and a second cutting insert 26 removably
secured in a second insert receiving pocket 30.
[0038] As shown in FIGS. 1 and 3, the tool axis AT defines a
forward-rearward direction D.sub.F, D.sub.R, and the cutting tool
20 has a direction of rotation R about the tool axis AT.
[0039] In some embodiments of the present invention, the first and
second cutting inserts 24, 26 may preferably be manufactured by
form pressing and sintering a cemented carbide, such as tungsten
carbide, and may be coated or uncoated.
[0040] Also in some embodiments of the present invention, the first
and second cutting inserts 24, 26 may be different from each
other.
[0041] As shown in FIGS. 1 to 5, the first insert receiving pocket
28 opens out at a forward end surface 32 of the cutting body 22,
and the second insert receiving pocket 30 is located axially
rearward of the first insert receiving pocket 28.
[0042] In some embodiments of the present invention, a helical chip
flute 34 may extend axially rearwardly from the forward end surface
32 of the cutting body 22, and the first and second insert
receiving pockets 28, 30 may communicate with the helical chip
flute 34.
[0043] Also in some embodiments of the present invention, as shown
in FIGS. 2 and 4, a first tool plane PT1 containing the tool axis
AT may intersect the first and second cutting inserts 24, 26.
[0044] It should be appreciated that configuring the first tool
plane PT1 to intersect the first and second cutting inserts 24, 26
such that the first and second cutting inserts 24, 26
circumferentially overlap, advantageously enables the helix angle
of the chip flute 34 to be minimized and thus the total number of
chip flutes 34 formed in the cutting body 22 to be maximized.
[0045] As shown in FIGS. 9 to 12, the first cutting insert 24 has
opposing first insert front and back end surfaces 36, 38 with a
first insert peripheral side surface 40 extending therebetween and
a first insert axis A1 extending therethrough, and at least one
first insert front major cutting edge 42 formed at the intersection
of the first insert front end surface 36 and the first insert
peripheral side surface 40.
[0046] In some embodiments of the present invention, the first
cutting insert 24 may exhibit rotational symmetry about the first
insert axis A1.
[0047] As shown in FIGS. 3 and 4, one of the at least one first
insert front major cutting edge 42 is operative.
[0048] In some embodiments of the present invention, two first
insert front major cutting edges 42 may be formed at the
intersection of the first insert front end surface 36 and the first
insert peripheral side surface 40, and the two first insert front
major cutting edges 42 may be spaced apart by two first insert
front minor cutting edges 44.
[0049] Also in some embodiments of the present invention, the first
insert front and back end surfaces 36, 38 may be non-identical.
[0050] Further in some embodiments of the present invention, no
cutting edges may be formed at the intersection of the first insert
back end surface 38 and the first insert peripheral side surface
40.
[0051] As shown in FIGS. 13 and 14, the second cutting insert 26
has opposing second insert front and back end surfaces 46, 48 with
a second insert peripheral side surface 50 extending therebetween
and a second insert axis A2 extending therethrough, and at least
one second insert front major cutting edge 52 formed at the
intersection of the second insert front end surface 46 and the
second insert peripheral side surface 50.
[0052] In some embodiments of the present invention, the second
cutting insert 26 may exhibit rotational symmetry about the second
insert axis A2.
[0053] As shown in FIGS. 3 and 4, one of the at least one second
insert front major cutting edge 52 is operative.
[0054] In some embodiments of the present invention, two spaced
apart second insert front major cutting edges 52 may be formed at
the intersection of the second insert front end surface 46 and the
second insert peripheral side surface 50.
[0055] Also in some embodiments of the present invention, the
second insert front and back end surfaces 46, 48 may be identical,
and at least one second insert back major cutting edge 54 may be
formed at the intersection of the second insert back end surface 46
and the second insert peripheral side surface 50.
[0056] As shown in FIGS. 3, 4, 7 and 8, the first insert receiving
pocket 28 has a first insert seat surface 56 with a first insert
axial support wall 58 transverse thereto, and the first insert seat
surface 56 is in contact with a first portion of the first insert
peripheral side surface 40, providing radial support for the first
cutting insert 24, and the first insert axial support wall 58 is in
contact with a second portion of the first insert peripheral side
surface 40, providing axial support for the first cutting insert
24.
[0057] In some embodiments of the present invention, the first
insert seat surface 56 may be planar.
[0058] Also in some embodiments of the present invention, the first
insert seat surface 56 may be contiguous with the forward end
surface 32 of the cutting body 22.
[0059] As shown in FIGS. 6 and 7, the first insert axial support
wall 58 may be located radially outward of the first insert seat
surface 56.
[0060] It should be appreciated that FIG. 6 is an end view of the
cutting tool 20 viewed along the tool axis AT.
[0061] In some embodiments of the present invention, the first
insert axial support wall 58 may be spaced apart from the first
insert seat surface 56 by a first insert axial stress relief groove
60.
[0062] Also in some embodiments of the present invention, the first
insert axial support wall 58 may be planar.
[0063] Further in some embodiments of the present invention, the
first insert peripheral side surface 40 may be in contact with the
entire first insert axial support wall 58.
[0064] As shown in FIGS. 3 and 4, the second insert receiving
pocket 30 may have a second insert seat surface 62 with a second
insert tangential support wall 64 transverse thereto.
[0065] In some embodiments of the present invention, as shown in
FIG. 7, the second insert seat surface 62 may be in contact with
the second insert peripheral side surface 50, providing radial
support for the second cutting insert 26.
[0066] Also in some embodiments of the present invention, the
second insert seat surface 62 may be planar.
[0067] Further in some embodiments of the present invention, as
shown in FIG. 7, the entire second insert seat surface 62 may be
located radially outward of the first insert seat surface 56.
[0068] It should be appreciated that configuring the second insert
seat surface 62 to be located radially outward of the first insert
seat surface 56 enables the formation of the first insert axial
support wall 58.
[0069] Yet further in some embodiments of the present invention,
the second insert tangential support wall 64 may be in contact with
the second insert back end surface 48, providing tangential support
for the second cutting insert 26, and the second insert front end
surface 46 may be located rotationally forward of the second insert
back end surface 48.
[0070] As shown in FIGS. 9 to 12, the first insert peripheral side
surface 40 may include two opposing first insert major side
surfaces 66a, 66b and two opposing first insert minor side surfaces
68a, 68b.
[0071] In some embodiments of the present invention, as shown in
FIG. 7, one of the two first insert major side surfaces 66a, 66b
may be in contact with the first insert seat surface 56, and one of
the two first insert minor side surfaces 68a, 68b may be in contact
with the first insert axial support wall 58.
[0072] Also in some embodiments of the present invention, one of
the two first insert minor side surfaces 68a, 68b may be in contact
with the entire first insert axial support wall 58.
[0073] Further in some embodiments of the present invention, each
of the two first insert major side surfaces 66a, 66b and each of
the two first insert minor side surfaces 68a, 68b may be contiguous
with the first insert back end surface 38.
[0074] As shown in FIGS. 9 to 12, the first cutting insert 24 may
have a first insert minimum length L1.sub.MIN measured as the
shortest distance between the two first minor side surfaces 68a,
68b, and a first insert maximum width W1.sub.MAX between the two
first insert major side surfaces 66a, 66b measured perpendicular to
the first insert axis A1 and the first insert minimum length
L1.sub.MIN.
[0075] In some embodiments of the present invention, the first
insert minimum length L1.sub.MIN may be greater than the first
insert maximum width W1.sub.MAX.
[0076] Also in some embodiments of the present invention, each of
the at least one first insert front major cutting edge 42 may be
formed at the intersection of the first insert front end surface 36
and one of the two first insert major side surfaces 66a, 66b.
[0077] Further in some embodiments of the present invention, each
of the two first insert front minor cutting edges 44 may be formed
at the intersection of the first insert front end surface 36 and
one of the two first minor side surfaces 68a, 68b.
[0078] As shown in FIGS. 9 and 12, a first insert through bore 70
may extend between and open out to the two first insert major side
surfaces 66a, 66b.
[0079] In some embodiments of the present invention, the first
insert through bore 70 may extend along a first insert bore axis
AB1, and the first insert maximum width W1.sub.MAX may be measured
parallel to the first insert bore axis AB1.
[0080] Also in some embodiments of the present invention, a first
insert bore plane PB1 may contain the first insert bore axis AB1
and the first insert axis A1, and the first insert minimum length
L1.sub.MIN may be measured perpendicular to the first insert bore
plane PB1.
[0081] As shown in FIGS. 3, 4, 7 and 8, a first clamping screw 72
may extend through the first insert through bore 70 and threadingly
engage a first screw bore 74 in the first insert seat surface
56.
[0082] As shown in FIGS. 13 and 14, the second insert peripheral
side surface 50 may include two opposing second insert major side
surfaces 76a, 76b and two opposing second insert minor side
surfaces 78a, 78b.
[0083] In some embodiments of the present invention, as shown in
FIG. 7, one of the two second insert major side surfaces 76a, 76b
may be in contact with the second insert seat surface 62.
[0084] As shown in FIGS. 13 and 14, the second cutting insert 26
may have a second insert minimum length L2.sub.MIN measured as the
shortest distance between the two second minor side surfaces 78a,
78b, and a second insert maximum width W2.sub.MAX between the two
second insert major side surfaces 76a, 76b measured perpendicular
to the second insert axis A2 and the second insert minimum length
L2.sub.MIN.
[0085] In some embodiments of the present invention, the second
insert minimum length L2.sub.MIN may be greater than the second
insert maximum width W2.sub.MAX.
[0086] Also in some embodiments of the present invention, the first
insert maximum width W1.sub.MAX may be greater than the second
insert maximum width W2.sub.MAX.
[0087] Further in some embodiments of the present invention, the
first insert maximum width W1.sub.MAX may be at least six-fifths of
the second insert maximum width W2.sub.MAX.
[0088] It should be appreciated that configuring the first insert
maximum width W1.sub.MAX to be greater than the second insert
maximum width W2.sub.MAX enables stable mounting of the first and
second cutting inserts 24, 26 in their respective first and second
insert receiving pockets 28, 30, whilst arranging the operative
first and second insert front major cutting edges 42, 52 to perform
machining operations at the same cutting diameter.
[0089] As shown in FIGS. 13 and 14, a second insert through bore 80
may extend between and open out to the two second insert major side
surfaces 76a, 76b.
[0090] In some embodiments of the present invention, the second
insert through bore 80 may extend along a second insert bore axis
AB2, and the second insert maximum width W2.sub.MAX may be measured
parallel to the second insert bore axis AB2.
[0091] Also in some embodiments of the present invention, a second
insert bore plane PB2 may contain the second insert bore axis AB2
and the second insert axis A2, and the second insert minimum length
L2.sub.MIN may be measured perpendicular to the second insert bore
plane PB2.
[0092] Further in some embodiments of the present invention, the
second cutting insert 26 may exhibit rotational symmetry about the
second insert bore axis AB2.
[0093] As shown in FIGS. 3 and 4, a second clamping screw 82 may
extend through the second insert through bore 80 and threadingly
engage a second screw bore 102 in the second insert seat surface
62.
[0094] As shown in FIG. 4, a second tool plane PT2 perpendicular to
the tool axis AT intersects the operative first insert front major
cutting edge 42 and the operative second insert front major cutting
edge 52, or in other words, the operative first and second insert
front major cutting edges 42, 52 axially overlap.
[0095] In some embodiments of the present invention, the second
tool plane PT2 may intersect each of the least one first insert
front major cutting edge 42 and each of the least one second insert
front major cutting edge 52.
[0096] For embodiments of the present invention in which the second
insert front and back end surfaces 46, 48 are identical, the second
tool plane PT2 may also intersect each of the least one second
insert back major cutting edge 54.
[0097] As shown in FIGS. 1 and 2, the cutting tool 20 may also have
a plurality of second cutting inserts 26 arranged along the chip
flute 34 with axially overlapping operative second insert front
major cutting edges 52.
[0098] It should be appreciated that configuring the second tool
plane PT2 to intersect the operative first insert and operative
second insert front major cutting edges 42, 52 advantageously
enables the provision of a continuous cutting edge along the chip
flute 34.
[0099] As shown in FIG. 4, in a side view of the cutting tool 20
perpendicular to the tool axis AT, a raised shoulder surface 84
adjacent the first insert axial support wall 58 is at least
partially obscured by the second cutting insert 26.
[0100] It should be appreciated that configuring the raised
shoulder surface 84 to be at least partially obscured by the second
cutting insert 26 advantageously enables the first and second
cutting inserts 24, 26 to be arranged in close axial proximity,
whilst the first insert axial support wall 58 provides axial
support for the first cutting insert 24.
[0101] It should also be appreciated that the provision of axial
support for the first cutting insert 24 is an important
requirement, as the first insert receiving pocket 28 opens out at
the forward end surface 32 of the cutting body 22, and the first
cutting insert 24 is subjected to substantial axial cutting forces
during machining operations.
[0102] As shown in FIGS. 6 and 7, the shoulder surface 84 may be
spaced apart from the first insert seat surface 56 by the first
insert axial support wall 58.
[0103] In some embodiments of the present invention, the shoulder
surface 84 may be located radially outward of the first insert seat
surface 56.
[0104] Also in some embodiments of the present invention, as shown
in FIG. 4, the second tool plane PT2 may intersect the shoulder
surface 84.
[0105] Further in some embodiments of the present invention, the
shoulder surface 84 may be contiguous with the first insert axial
support wall 58.
[0106] As shown in FIG. 4, in the side view of the cutting tool 20,
no portion of the shoulder surface 84 may be obscured by the first
cutting insert 24.
[0107] In some embodiments of the present invention, the shoulder
surface 84 may form a portion of the second insert seat surface
62.
[0108] It should be appreciated that for embodiments of the present
invention that the second insert seat surface 62 is planar, the
shoulder surface 84 may be a coplanar extension thereof.
[0109] In some embodiments of the present invention, as shown in
FIG. 7, one of the two second insert major side surfaces 76a, 76b
may be in contact with the shoulder surface 84.
[0110] In other embodiments of the present invention (not shown),
the shoulder surface 84 may be distinct from the second insert seat
surface 62, for example, offset therefrom or inclined thereto, such
that neither of the two second insert major side surfaces 76a, 76b
are in contact with the shoulder surface 84.
[0111] As shown in FIGS. 4 and 7, the first tool plane PT1 may
intersect the shoulder surface 84 and the first insert peripheral
side surface 40.
[0112] In some embodiments of the present invention, the first tool
plane PT1 may intersect the first insert axial support wall 58.
[0113] As shown in FIG. 7, in a cross-section taken in the first
tool plane PT1, the shoulder surface 84 and the first insert axial
support wall 58 may form an internal first pocket angle .alpha.1.
More particularly, in this cross-section, the shoulder surface 84
and the first insert axial support wall 58 form a step having the
aforementioned internal first pocket angle .alpha.1.
[0114] In some embodiments of the present invention, the first
pocket angle .alpha.1 may have a range from 70 to 110 degrees.
[0115] It should also be appreciated that use of the terms
"internal angle" and "external angle" throughout the description
and claims refers to an angle between two surface components of a
pair of surfaces as measured internal and external to the member on
which the two surface components are formed, respectively.
[0116] As shown in FIG. 12, the first insert axis A1 may intersect
the first insert front and back end surfaces 36, 38 at front and
back end points N1, N2, respectively, and a first insert median
plane M perpendicular to the first insert axis A1 may be located
midway between the front and back end points N1, N2.
[0117] In some embodiments of the present invention, as shown in
FIG. 5, the first insert median plane M may intersect the first
insert axial support wall 58 and the second cutting insert 26.
[0118] Also in some embodiments of the present invention, the first
insert median plane M may intersect the shoulder surface 84.
[0119] It should be appreciated that although FIG. 5 shows a side
view of the cutting tool 20, with the first cutting insert 24 and
the first clamping screw 72 removed, the first insert median plane
M associated with the first cutting insert 24 is shown.
[0120] It should be appreciated that for embodiments of the present
invention in which the first insert peripheral side surface 40 is
in contact with the entire first insert axial support wall 58,
configuring the first insert median plane M to intersect the first
insert axial support wall 58 and the second cutting insert 26,
advantageously enables the helix angle of the chip flute 34 to be
minimized whilst providing central and stable axial support for the
first cutting insert 24.
[0121] As shown in FIGS. 3, 4, 6 and 8, the first insert receiving
pocket 28 may include a first insert tangential support wall 86
transverse to the first insert seat surface 56, and the first
insert tangential support wall 86 may be in contact with the first
insert back end surface 38, providing tangential support for the
first cutting insert 24.
[0122] In some embodiments of the present invention, as shown in
FIGS. 3 and 6, the first insert tangential support wall 86 may face
the direction of rotation R.
[0123] Also in some embodiments of the present invention, the first
insert tangential support wall 86 may be contiguous with the
forward end surface 32 of the cutting body 22.
[0124] Further in some embodiments of the present invention, the
first insert tangential support wall 86 may be planar.
[0125] As shown in FIG. 5, in a side view of the cutting body 22,
the first insert axial and first insert tangential support walls
58, 86 form an external acute second pocket angle .alpha.2.
[0126] In some embodiments of the present invention, the second
pocket angle .alpha.2 may have a range from 75 to 88 degrees.
[0127] It should be appreciated that with respect to the first
insert receiving pocket 28, FIG. 5 also represents a side view of
the cutting body 22, in view of the first cutting insert 24 and the
first clamping screw 72 being removed.
[0128] It should also be appreciated that configuring the first
insert axial and first insert tangential support walls 58, 86 to
form an external acute second pocket angle .alpha.2 results in
tangential cutting forces acting on the first insert tangential
support wall 86 being partially directed towards the first insert
axial support wall 58, and axial cutting forces acting on the first
insert axial support wall 58 being partially directed towards the
first insert tangential support wall 86, which advantageously
results in a stable clamping arrangement and reduced axial and
tangential cutting forces acting on the first clamping screw 72
during machining operations.
[0129] As shown in FIGS. 6 and 8, the first insert tangential
support wall 86 may be located radially outward of the first insert
seat surface 56.
[0130] Yet further in some embodiments of the present invention,
the first insert tangential support wall 86 may be spaced apart
from the first insert seat surface 56 by a first insert tangential
stress relief groove 88.
[0131] As shown in FIG. 8, in a cross-section taken in a third tool
plane PT3 perpendicular to the tool axis AT and intersecting the
first insert seat surface 56 and the first insert tangential
support wall 86, the first insert seat surface 56 and the first
insert tangential support wall 86 may form an external acute third
pocket angle .alpha.3.
[0132] In some embodiments of the present invention, the third
pocket angle .alpha.3 may have a range from 65 to 85 degrees.
[0133] Also in some embodiments of the present invention, the third
tool plane PT3 may intersect each of the at least one first insert
front major cutting edge 42.
[0134] It should be appreciated that configuring the first insert
seat surface 56 and the first insert tangential support wall 86 to
form an external acute third pocket angle .alpha.3 results in
tangential cutting forces acting on the first insert tangential
support wall 86 being partially directed towards the first insert
seat surface 56, which advantageously results in a stable clamping
arrangement and reduced tangential cutting forces acting on the
first clamping screw 72 during machining operations.
[0135] As shown in FIG. 7, the first clamping screw 72 may have a
first head portion 90 and a first shank portion 92 extending
therefrom, and the first head portion 90 may be entirely located
radially outward of the shoulder surface 84.
[0136] It should be appreciated that configuring the first head
portion 90 to be entirely located radially outward of the shoulder
surface 84 results in clamping contact between the first head
portion 90 and the first through bore 70 radially outward of the
first insert axial support wall 58.
[0137] As shown in FIGS. 3 and 4, a tangential end wall 94
contiguous with the shoulder surface 84 may face the direction of
rotation R, and the tangential end wall 94 may be located
rotationally forward of the first insert tangential support wall
86.In some embodiments of the present invention, as shown in FIG.
4, the second tool plane PT2 may intersect the tangential end wall
94.
[0138] Also in some embodiments of the present invention, the
tangential end wall 94 may be contiguous with the first insert
axial support wall 58.
[0139] As seen in FIG. 6, the first insert axial support wall 58
may have a height above the first insert seat surface 56 that
varies. For example, the height of the first insert axial support
wall 58 may increase in the direction of rotation R. The height of
the first insert axial support wall 58 above the first insert seat
surface 56 may vary from an axial support wall minimum height
HA.sub.MIN closest to the first insert tangential support wall 86
to an axial support wall maximum height HA.sub.MAX closest to the
tangential end wall 94.
[0140] To provide an adequate surface area for axial support of the
first cutting insert 24, the minimum height HA.sub.MIN of the first
insert axial support wall 58 is preferably no less than 15% of the
first insert maximum width W1.sub.MAX.
[0141] Further in some embodiments of the present invention, the
tangential end wall 94 may not make contact with the first cutting
insert 24.
[0142] As shown in FIGS. 1, 6 and 8, the cutting body 22 may have a
cylindrical outer peripheral surface 96 extending axially
rearwardly from the forward end surface 32, and the first insert
tangential support wall 86 may intersect the outer peripheral
surface 96.
[0143] It should be appreciated that for embodiments of the present
invention that the shoulder surface 84 is located radially outward
of the first insert seat surface 56, the shoulder surface 84 may
also be located radially inward of the outer peripheral surface
96.
[0144] In some embodiments of the present invention, as shown in
FIGS. 8 and 11, the first insert back end surface 38 may have a
pair of first insert back abutment surfaces 98a, 98b, and only one
of the two first insert back abutment surfaces 98a, 98b may be in
contact with the first insert tangential support wall 86, with
contact occurring at the radially outermost portion of the first
insert tangential support wall 86.
[0145] Also in some embodiments of the present invention, the pair
of first insert back abutment surfaces 98a, 98b may be spaced apart
by an intermediate surface 100.
[0146] It should be appreciated that apart from only one of the two
first insert back abutment surfaces 98a, 98b being in contact with
the first insert tangential support wall 86, no other portion of
the first insert back end surface 38 is in contact with the first
insert receiving pocket 28.
[0147] It should also be appreciated that configuring the radially
outermost portion of the first insert tangential support wall 86 to
be in contact with the first insert back end surface 38 results in
tangential support for the first cutting insert 24 being provided
radially outward of the region of clamping contact between the
first head portion 90 and the first insert through bore 70, which
advantageously results in a stable clamping arrangement and reduced
tangential cutting forces acting on the first clamping screw 72
during machining operations.
[0148] As shown in FIG. 12, in a cross-section taken in a first
insert major plane PM1 containing the first insert axis A1, the
first insert back end surface 38 may have a convex shape.
[0149] In some embodiments of the present invention, in the
cross-section taken in the first insert major plane PM1, the pair
of first insert back abutment surfaces 98a, 98b may form an
internal obtuse first insert angle .gamma.1.
[0150] Also in some embodiments of the present invention, the first
insert major plane PM1 may intersect each of the at least one first
insert front major cutting edge 42.
[0151] Further in some embodiments of the present invention, the
first insert angle .gamma.1 may have a range from 130 to 170
degrees.
[0152] It should be appreciated that the first insert angle
.gamma.1 may be approximately twice the third pocket angle
.alpha.3, to ensure adequate contact between one of the two first
insert back abutment surfaces 98a, 98b and the first insert
tangential support wall 86 in each index position of the first
cutting insert 24.
[0153] In some embodiments of the present invention, the first
insert major plane PM1 and the first insert bore plane PB1 may be
coplanar.
[0154] Also in some embodiments of the present invention, as shown
in FIG. 5, the first insert major plane PM1 may intersect the outer
peripheral surface 96 along its entire circumference.
[0155] It should be appreciated that although FIG. 5 shows a side
view of the cutting tool 20, with the first cutting insert 24 and
the first clamping screw 72 removed, the first insert major plane
PM1 associated with the first cutting insert 24 is shown.
[0156] As shown in FIG. 4, the operative first insert front major
cutting edge 42 may have a positive first insert axial rake angle
.beta.1, and the operative second insert front major cutting edge
52 may have a positive second axial rake angle .beta.2.
[0157] For embodiments of the present invention in which the second
insert front and back end surfaces 46, 48 are identical and the
second insert front end surface 46 is in contact with the second
insert tangential support wall 64 (not shown), the operative second
insert back major cutting edge 54 may have a positive second insert
axial rake angle .beta.2.
[0158] Although the present invention has been described to a
certain degree of particularity, it should be understood that
various alterations and modifications could be made without
departing from the spirit or scope of the invention as hereinafter
claimed.
* * * * *