Note: Descriptions are shown in the official language in which they were submitted.
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RAMPING INSERT AND HIGH-FEED MILLING TOOL ASSEMBLY
FIELD OF THE INVENTION
The subject matter of the present application relates to high-feed milling
tool assemblies
comprising tools and inserts for ramping and high-feed metal machining
operations. More
particularly, the subject matter is directed to ramping inserts configured to
be indexed to exactly
four operative positions on a tool (two indexable positions per rake surface).
BACKGROUND OF THE INVENTION
High-feed milling assemblies are typically characterized with a construction
designed to
carry out shouldering operations within a chip load range of 0.5mm to 2mm. A
combination of
moderate chip load and primarily axially directed forces can allow such
assemblies to achieve a
relatively high tool feed rate.
For example, US 2005/0111925A1 discloses a high-feed milling tool. Of note is
the
approach angle (K') shown in Fig. 9 and related explanation how a moderate
cutting depth is
compensated for by an increased (i.e. high-feed) tool feed rate (Fig. 11, par.
110051]). A ramping
operation is explained with reference to Figs. 13 and 14 in par. [0056].
Additionally, the inserts are
stated to be indexable to four different positions (par. 110058]). It will
also be noted that the insert
disclosed has a significantly non-parallel peripheral surface extending from
the top side 15 to the
bottom side 16 to provide desired clearance. A further feature disclosed is
the provision of a chamfer
surface 35 for clearance (Fig. 5, par. 110047]).
WO 2014/156225 discloses another milling tool and cutting insert of interest.
As will be
best understood from at least Fig. 16 thereof, however, the cutting insert and
insert pocket shown
differs significantly from that described hereinbelow.
US 2013/0129432 discloses cutting inserts for being mounted in cutter bodies
for face
milling and ramping. The author thereof is of the opinion that it is not
possible to obtain unique axial
and radial position of a standard negative square cutting insert that allows
alternating high-feed face
milling and ramping with relief of the insert without changing the position of
the cutting inserts in
the cutter body, but notes that this is not the case with positive inserts
with natural relief (par.
110006]). Also, the inserts disclosed are configured to be indexable to
multiple different positions.
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SUMMARY OF THE INVENTION
Generally speaking, cutting inserts which can be indexed to a greater number
of positions
are more cost effective than cutting inserts configured to be indexed to a
lower number of positions.
Nonetheless, it is believed that a ramping insert in accordance with the
subject matter of the present
application which is only configured for four indexable positions and
necessitates an arguably
complex tool to provide necessary clearance, but can be comparatively simply
manufactured and is
still capable of performing ramping and high-feed operations, can be
competitive with cutting
inserts having a larger number of indexable positions or tools having a
simpler design.
In accordance with a first aspect of the subject matter of the present
application, there is
provided a ramping insert comprising: opposing first and second rake surfaces;
an insert peripheral
surface connecting the first and second rake surfaces; an insert screw hole
opening out to opposing
sides of the insert peripheral surface, the insert screw hole having an insert
screw hole axis; and first
and second cutting edges extending along an intersection of the insert
peripheral surface and a
corresponding one of the first and second rake surfaces; each of the first and
second cutting edges
comprising: a first ramping sub-edge; a first side sub-edge; a first feed sub-
edge connected to the
first ramping sub-edge and the first side sub-edge; a second ramping sub-edge
connected to the first
side sub-edge; a second side sub-edge connected to the first ramping sub-edge;
and a second feed
sub-edge connected to the second ramping sub-edge and the second side sub-
edge; wherein: each of
the ramping and feed sub-edges is longer than each of the side sub-edges; a
maximum rake surface
length of each rake surface is measurable between the first and second side
sub-edges thereof, and
each of the ramping and feed sub-edges converge with increasing proximity to
the side sub-edge to
which they are both connected.
In accordance with another aspect of the subject matter of the present
application, there is
provided a ramping insert comprising ramping and feed sub-edges converging
with increasing
proximity to the side sub-edge to which they are both connected.
In accordance with still another aspect of the subject matter of the present
application, there
is provided a ramping insert comprising, at each of two opposing rake surfaces
thereof, two ramping
sub-edges, two feed sub-edges, and two side sub-edges; each of the ramping and
feed sub-edges
being longer than each side sub-edge.
In accordance with yet another aspect of the subject matter of the present
application, there is
provided a ramping insert comprising: opposing first and second rake surfaces;
an insert peripheral
surface; first and second cutting edges extending along an intersection of the
insert peripheral
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surface and a corresponding one of the first and second rake surfaces; and an
insert screw hole
opening out to opposing sides of the insert peripheral surface; the insert
peripheral surface
comprising a first ramping sub-surface; a first side sub-surface; a first feed
sub-surface connected to
the first ramping sub-surface and first side sub-surface; a second ramping sub-
surface connected to
the first side sub-surface; a second side sub-surface connected to the first
ramping sub-surface; and a
second feed sub-surface connected to the second ramping sub-surface and second
side sub-surface.
In accordance with another aspect of the subject matter of the present
application, there is
provided a ramping insert comprising a ramping sub-edge and a feed sub-edge;
wherein the ramping
sub-edge comprises a sharp ramping corner portion at an end thereof proximate
to the feed sub-
edge; and the feed sub-edge comprises a sharp feed corner portion at an end
thereof proximate to the
feed sub-edge.
Stated differently, according to any of the aspects, the ramping and feed sub-
edges of a
ramping insert can be connected via two adjacent sharp corner portions.
In accordance with a further aspect, there is provided a high-feed milling
tool configured for
rotating about a rotation axis in a rotation direction, the rotation axis
defining forward and rearward
directions, the tool comprising an insert pocket; the insert pocket comprising
a pocket top surface
which in turn comprises first and second pocket top sub-surfaces; the first
pocket top sub-surface
being adjacent to a tool peripheral surface and extending more in a forward
direction with increasing
proximity thereto; the second pocket top sub-surface being adjacent to a
pocket side surface and
extending more in the forward direction with increasing proximity thereto.
In accordance with another aspect, there is provided a high-feed milling tool
configured for
rotating about a rotation axis in a rotation direction, the rotation axis
defining forward and rearward
directions, the tool comprising: a tool end surface and a circumferentially
extending tool peripheral
surface extending rearward therefrom; a flute formed at an intersection of the
tool end surface and
the tool peripheral surface and extending rearward therefrom; and an insert
pocket formed at an
intersection of the tool end surface and the tool peripheral surface and
opening out to the flute, the
insert pocket comprising: a pocket back surface extending inwardly from the
tool peripheral surface
and facing the rotation direction; a pocket side surface extending from the
pocket back surface to the
flute and facing outwardly; a pocket top surface extending inwardly from the
tool peripheral surface
to the pocket side surface, and also extending from the pocket back surface to
the flute; and a
pocket screw hole opening out to the pocket top surface; wherein: the pocket
back surface comprises
a back abutment sub-surface; the pocket top surface comprises first and second
pocket top sub-
surfaces; the first pocket top sub-surface is adjacent to the tool
peripheral surface and extends
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more in the forward direction with increasing proximity thereto; the second
pocket top sub-surface
is adjacent to the pocket side surface and extends more in the forward
direction with increasing
proximity thereto; and the first and second pocket top sub-surfaces extend
more in the forward
direction with increasing proximity to the flute.
In accordance with still another aspect, there is provided a high-feed milling
tool assembly
comprising, in combination: a ramping insert which can be according to the
first aspect; a tool which
can be according to the previous aspect; and a screw fastening the ramping
insert to the insert pocket
of the tool via the insert and pocket screw holes; the tool and ramping insert
being configured for
abutment of: the insert peripheral surface with each of the pocket side
surface and first and second
pocket top sub-surfaces; and one of the first and second rake surfaces with
the pocket back surface.
In accordance with another aspect, there is provided a high-feed milling tool
assembly
comprising, in combination a tool according to one of the tool aspects
described above and a cutting
insert according to one of the cutting insert aspects described above.
It will be understood that the above-said is a summary, and that any of the
aspects above
may further comprise any of the features described hereinbelow. Specifically,
the following features,
either alone or in combination, may be applicable to any of the above aspects:
A. An insert can comprise first and second cutting edges which extend along
an intersection of an
insert peripheral surface and a corresponding one of first and second rake
surfaces.
B. First and second cutting edges can extend further than first and second
rake surfaces from a
median height plane. Feed sub-edges, at least at a connection point with side
sub-edges, can extend
further than ramping sub-edges, at least at a connection point of the ramping
sub-edges with side
sub-edges, from the median height plane. Each feed sub-edge can lie in a
single plane
perpendicular to a median height plane. Each ramping sub-edge can be slanted
such that with
increasing proximity to a connection point with a side sub-edge, it extends
closer to a median
height plane. Such slant can assist in strengthening the side sub-edge by
reducing a relatively high
rake angle that would otherwise form there, thereby improving machining
capability of the side
sub-edge.
C. First and second cutting edges can each have a negative land angle a
(i.e. slanted in an
inward-downward direction from the respective cutting edge to an associated
rake surface of the
insert). Negative lands are believed to be beneficial for at least high-feed
shouldering operations.
D. An insert can comprise opposing first and second rake surfaces.
E. Each rake surface can comprise a rake abutment surface. Each rake
abutment surface can
comprise first and second rake abutment sub-surfaces respectively located on
opposing sides of a
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median length plane. Each rake abutment sub-surface can be slanted such that
with increasing
proximity to the median length plane there is greater extension from a median
height plane.
F. Rake surfaces of an insert can be identical.
G. First and second rake surfaces can be devoid of projecting portions.
Particularly, projecting
portions which may impede chip flow. The first and second rake surfaces can
each comprise a
central rake surface region which can be planar.
H. An insert can comprise an insert peripheral surface. The insert
peripheral surface can connect
first and second rake surfaces of the insert.
I. An insert peripheral surface can comprise: a first ramping sub-surface; a
first side sub-surface; a
first feed sub-surface connected to the first ramping sub-surface and first
side sub-surface; a
second ramping sub-surface connected to the first side sub-surface; a second
side sub-surface
connected to the first ramping sub-surface; and a second feed sub-surface
connected to the second
ramping sub-surface and second side sub-surface.
J. An insert peripheral surface can extend parallel from a first cutting edge
to a second cutting edge.
By being devoid of slanted clearance surfaces (e.g., such as clearance surface
"22" disclosed in US
2005/0111925A1), providing clearance for an insert can result in a more
complex tool design.
Nonetheless, it is believed that such design can result in a simpler insert
manufacturing process,
e.g. an insert may be able to be pressed to final dimensions, which is
believed to offset known
disadvantages.
K. An insert peripheral surface can be devoid of relief portions. By not
having relief portions
(e.g., such as chamfer surface "35" disclosed in US 2005/0111925A1), providing
clearance for an
insert can result in a more complex tool design. Nonetheless, it is believed
that such design can
result in a simpler insert manufacturing process, e.g. an insert may be able
to be pressed to final
dimensions, which is believed to offset known disadvantages.
L. An insert can comprise an insert screw hole opening out to opposing
sides of an insert
peripheral surface. The insert screw hole can, at each side of the insert
peripheral surface, open out
to sub-surfaces of the insert peripheral surface which are slanted relative to
each other. The insert
screw hole can, at each side of the insert peripheral surface, open out to
both ramping and feed
sub-surfaces. The insert screw hole can open out to first ramping and feed sub-
surfaces as well as
second ramping and feed sub-surfaces. The insert screw hole can be equally
spaced from side sub-
surfaces. The insert screw hole can be equally spaced from rake surfaces. The
insert screw hole
can have an insert screw hole axis. The insert screw hole axis can lie along
(or be contained
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within) a median thickness plane and can be perpendicular to a median length
plane. A screw hole
thickness can increase with increasing proximity to each of first and second
rake surfaces.
M. Each cutting edge can comprise: a first ramping sub-edge; a first side sub-
edge; a first feed
sub-edge connected to the first ramping sub-edge and first side sub-edge; a
second ramping sub-
edge connected to the first side sub-edge; a second side sub-edge connected to
the first ramping
sub-edge; and a second feed sub-edge connected to the second ramping sub-edge
and second side
sub-edge.
N. Each ramping sub-edge can be longer than each side sub-edge. Even though
it is logical that
ramping sub-edges be smaller than other sub-edges of an insert, since the
ramping operation
occurs over only a small percentage of overall machining time, certainly
compared to a primary
shouldering operation, it has been found that providing a comparatively long
ramping sub-edge
can overcome some clearance difficulties which complicate insert manufacture.
0. Each feed sub-edge can be longer than each side sub-edge. This can
increase efficiency of a
primary milling operation, i.e. shouldering, which utilizes the feed sub-edge.
P. Each feed sub-edge can be longer than each ramping sub-edge. This can
increase efficiency of
a primary milling operation, i.e. shouldering, which utilizes the feed sub-
edge. A straight portion
of a ramping sub-edge can have a length of 70% 15% of the length of a
straight portion of an
adjacent feed sub-edge.
Q. Each of ramping and feed sub-edges can converge with increasing
proximity to a side sub-
edge to which they are both connected.
R. Each ramping sub-edge of a rake surface can form an internal acute
insert ramping angle k0
with a median length plane. The insert ramping angle k0 can fulfill the
condition (5 < k0 < 30 ).
The insert ramping angle k0 preferably fulfills the condition (15 5 ). A
sub-surface of an insert
peripheral surface which is adjacent to the ramping sub-edge can be oriented
at the same angle as
the ramping sub-edge.
S. Each feed sub-edge of a rake surface can form an internal acute insert
approach angle k 1 with
a median length plane. The insert approach angle k 1 can fulfill the condition
(5 < kl < 30 ). The
insert approach angle k 1 preferably fulfills the condition (15 5 ). A sub-
surface of the insert
peripheral surface which is adjacent to the feed sub-edge can be oriented at
the same angle as the
feed sub-edge.
T. An insert ramping angle k0 and an insert approach angle k 1 can be
equal. However, in certain
circumstances, e.g. for inserts configured for relatively smaller diameter
tools, the insert approach
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angle k 1 can be greater than the insert ramping angle kO. This can allow an
acceptable depth (and
hence feed rate) to be achieved even though the ramping function efficiency is
lessened.
U. A ramping insert can comprise a first internal angle R1 formed between a
straight extension
and an adjacent first ramping sub-edge, and a second internal angle R2 formed
between the
straight extension and an adjacent first feed sub-edge. The first internal
angle R1 can be unequal to
the second internal angle R2. Preferably, the first internal angle R1 is
greater than the second
internal angle R2.
V. Each side sub-edge can be bisected by a median length plane.
W. Each side sub-edge can comprise a straight portion. Unless stated
otherwise, the words
"straight portion" in connection with any sub-edge refers to a view facing a
rake surface (such as
that shown in Fig. 2C). It is believed that a side sub-edge with a straight
portion can provide a
significantly longer machining tool life than a curved side sub-edge. Such
straight portion can be
between 45 20% of an overall side sub-edge length. Generally speaking, the
word "overall" used
in connection a sub-edge length includes corner portions on both sides of the
sub-edge (until a
connection point with an adjacent sub-edge) and a remainder of the sub-edge
therebetween.
X. Straight portions of side sub-edges on the same rake surface can be
parallel to each other.
Straight portions of the side sub-edges on a first and second rake surface can
be parallel to each
other. The straight portion of a side sub-edge on a rake surface can be
parallel to only the straight
portion the same rake surface.
Y. A sub-surface of an insert peripheral surface which is adjacent to a side
sub-edge can be
oriented at the same angle as the side sub-edge. The side sub-edge straight
portions can have a
length which is 15% 5% of a maximum thickness of the insert measurable
parallel to a median
thickness plane and parallel to an insert screw hole axis.
Z. The side sub-edge straight portions can have a length which is 13% 5%
of an overall length
of a ramping sub-edge. The side sub-edge straight portions can have a length
which is 13% 5%
of an overall length of a feed sub-edge.
AA. Each side sub-edge can comprise a corner portion at each end thereof.
BB. Each ramping sub-edge can comprise a straight portion. Straight portions
of ramping sub-
edges on the same rake surface can be parallel to each other. Straight
portions of all ramping sub-
edges of an insert can be parallel to each other. A straight portion can be
85% 5% of an overall
ramping sub-edge length.
CC. Each ramping sub-edge can comprise a corner portion at each end thereof.
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DD. Each feed sub-edge can comprise a straight portion. Straight portions of
feed sub-edges on the
same rake surface can be parallel to each other. Straight portions of all feed
sub-edges of an insert
can be parallel to each other. A straight portion can be 85% 5% of an
overall feed sub-edge
length.
EE. Each feed sub-edge can comprise a corner portion at each end thereof.
FF. Straight portions of ramping and feed sub-edges can have a same length.
GG. A corner portion of a sub-edge can preferably be curved. Even though
curved corners can be
less precise than sharp or chamfered corners, such curvature can allow a
simplified manufacturing
process.
HH. A connection point between adjacent edges can be located at the middle of
a corner formed by
adjacent corner portions of adjacent edges. For example, each ramping sub-edge
can comprise a
corner portion and each feed sub-edge can comprise a corner portion adjacent
to the ramping sub-
edge's corner portion, and a connection point of the ramping sub-edge to the
feed sub-edge is
located at the middle of a corner formed by the adjacent corner portions.
Stated generally, ramping
and feed sub-edges can be connected at a connection point located at the
middle of a corner
formed by adjacent corner portions. Similarly, ramping and side sub-edges can
be connected at a
connection point located at the middle of a corner formed by adjacent corner
portions. Similarly,
feed and side sub-edges can be connected at a connection point located at the
middle of a corner
formed by adjacent corner portions.
II. Connection points of adjacent ramping and feed sub-edges can all lie on
a median thickness
plane. Connection points of adjacent ramping and feed sub-edges can be located
on different sides
of a median thickness plane.
JJ. Connection points of adjacent ramping and feed sub-edges can all lie on
a plane parallel to a
median thickness plane.
KK. A median thickness plan can contain a rake axis and an insert screw hole
axis, and can bisect
the first and second rake surfaces.
LL. A median length plane can bisect first and second rake surfaces and
extending perpendicular
to a median thickness plane.
MM. A median height plane can be located midway between first and second rake
surfaces and
can extending perpendicular to a median thickness plane and a median length
plane.
NN. A maximum thickness of an insert can be between connection points of
adjacent ramping
and feed sub-edges.
00. A maximum thickness of an insert can be measurable parallel to an
insert screw hole axis.
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PP. A maximum rake surface length on each rake surface can be measurable
between first and
second side sub-edges thereof. A length measurable parallel to a median length
plane and between
first and second side sub-edges can be greater than all other lengths
measurable between other sub-
edges and along a rake surface.
QQ. A longitudinal rake surface length LLR on each rake surface can be
measurable parallel to a
median length plane. The longitudinal rake surface length LLR can be greater
than a maximum
thickness TM measurable perpendicular to the median length plane. Preferably,
the longitudinal
rake surface length LLR fulfills the condition (2.3Tm 0.5Tm).
RR. A longitudinal rake surface length LLR on each rake surface can be greater
than a maximum
height HM measurable parallel to a height plane. Preferably, the maximum
length fulfills the
condition (1.5Hm 0.3Hm).
SS. A rake axis can extend through a center of first and second rake
surfaces.
TT. An insert can have a maximum height which is measurable parallel to a rake
axis.
UU. An insert can have a maximum thickness which is measurable parallel to a
median thickness
plane.
VV. An insert's maximum height can be greater than a maximum thickness
thereof.
WW. An insert can be 1800 rotationally symmetric about a rake axis extending
through a center of
first and second rake surfaces and/or 180 rotationally symmetric about an
insert screw hole axis
perpendicular to the rake axis and extending along an intersection of median
thickness and height
planes. An insert can be 180 rotationally symmetric about a height axis
perpendicular to the rake
axis and extending along an intersection of median thickness and height
planes.
XX. Each ramping sub-edge can comprise a sharp ramp corner portion, said sharp
ramp corner
portion being a corner portion of the ramping sub-edge closest to a feed sub-
edge.
YY. Each feed sub-edge can comprise a sharp feed corner portion adjacent to
a sharp ramp corner
portion.
ZZ. A straight extension can be defined between discontinuity points of
sharp ramp and feed
corner portions. The straight extension can have a length between 0.5mm to
2.0mm. Preferably,
the straight extension can have a length less than 0.75mm. The straight
extension can have a
length smaller than a quarter of the length of a straight portion of a feed
sub-edge. Preferably, the
straight extension has a length smaller than or equal to a sixth of the length
of the straight portion
of the feed sub-edge.
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AAA. First and second cutting edges can each lie in a plane. It will be
understood that this means
that each of the first and second cutting edges lie in different planes.
Although the different planes
can preferably be parallel to each other.
BBB. A tool can be configured for rotating about a rotation axis in a rotation
direction, the rotation
axis defining forward and rearward directions.
CCC. A tool can comprise a tool end surface and a circumferentially extending
tool peripheral
surface extending rearward therefrom.
DDD. A flute can be formed at intersection of a tool end surface and a tool
peripheral surface and
can extend rearward therefrom.
EEE. An insert pocket can be formed at an intersection of a tool end surface
and a tool peripheral
surface. The insert pocket can open out to a flute.
FFF. An insert pocket can comprise a pocket side surface. The pocket side
surface can extend from
a pocket back surface to a flute. The pocket side surface can extend from a
pocket top surface to a
flute. The pocket side surface can face outwardly.
GGG. A pocket side surface can comprise a side abutment sub-surface. The side
abutment surface
can extend perpendicular to a tool plane extending perpendicular to a rotation
axis.
HHH. An insert pocket can comprise a pocket back surface. The pocket back
surface can extend
inward from a tool peripheral surface. The pocket back surface can face a
rotation direction.
III. A pocket back surface can comprise a back abutment surface. A back
abutment surface can be
formed with a back surface relief recess dividing the back abutment surface
into two back
abutment sub-surfaces. While such division can reduce contact area with a
cutting insert, it can
accommodate a less precisely manufactured insert and hence can simplify insert
manufacture. The
back abutment surface can be axially located along at a lower half of an
insert pocket (i.e. a half of
the insert pocket closest to a tool end surface).
JJJ. A back abutment surface or sub-surface can be slanted relative to a
pocket screw hole axis,
such that with increasing proximity to the tool end surface the back abutment
sub-surface extends
further in the rotation direction.
KKK. An insert pocket can comprise a pocket top surface. The pocket top
surface can extend
inwardly from a tool peripheral surface to a pocket side surface. The pocket
top surface can extend
from a pocket back surface to a flute.
LLL. A pocket top surface can comprise first and second pocket top sub-
surfaces.
MMM. A first pocket top sub-surface can be adjacent to a tool peripheral
surface and can extend
more in a forward direction with increasing proximity to the tool peripheral
surface.
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NNN. A second pocket top sub-surface can be adjacent to a pocket side surface
and can extend
more in a forward direction with increasing proximity to the pocket side
surface.
000. Both first and second pocket top sub-surfaces can extend more in a
forward direction with
increasing proximity to a flute. While such extension is less desirable for
machining, it is believed
to be offset by the possibility to manufacture a simpler insert.
PPP. An insert pocket can comprise a pocket screw hole. The pocket screw hole
can open out to a
pocket top surface.
QQQ. An assembly can comprise a tool, ramping insert and screw configured to
fasten the insert
to an insert pocket of the tool.
RRR. An assembly can comprise multiple ramping inserts.
SSS. A tool and ramping insert can be configured for abutment of the ramping
insert's insert
peripheral surface with the tool's pocket side surface and first and second
pocket top sub-surfaces,
and abutment of one of the ramping insert's first and second rake surfaces
with the tool's pocket
back surface. The ramping insert can be configured so that it can be indexed
so that a different
portion of the insert peripheral surface abuts the tool's pocket side surface
and first and second
pocket top sub-surfaces. Additionally, the ramping insert can be configured so
that it can be
reversed so that the other rake surface contacts the tool's pocket back
surface (and also indexed in
the reversed position). The tool and/or ramping insert can be configured for
fastening the ramping
insert to an insert pocket in exactly four different positions.
TTT. In a view of a tool's pocket back surface in a direction opposite to the
rotation direction, a first
pocket top sub-surface can form an internal acute first tool angle k2 with a
tool plane extending
perpendicular to the rotation axis and a second pocket top sub-surface can
form an internal acute
second tool angle k3 with the tool plane. The first and second tool angles can
fulfill the condition
(6 < k2, k3 < 310). It is believed better performance can be achieved with
approach angles closer
to 15.5 . Accordingly, the first and second tool angles preferably fulfill the
condition (15.5 5 ).
UUU. First and second tool angles k2, k3 can be equal.
VVV. First and second pocket top sub-surfaces can extend an equal radial
distance. The term
"radial" is used in a general sense only and, as will be understood from the
drawings, refers to
general inward-outward directions of a tool (in a plane perpendicular to a
rotation axis thereof) and
not necessarily a direction directed exactly to the rotation axis.
WWW. A pocket top surface can be formed with a top surface relief recess
between first and
second pocket top sub-surfaces. While having a top surface relief recess
between first and second
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pocket top sub-surfaces can reduce contact area with a cutting insert, it can
accommodate a less
precisely manufactured insert and hence can simplify insert manufacture.
XXX. A tool can comprise a number (n) of insert pockets. The insert pockets
can be equally
circumferentially spaced along a tool peripheral surface. The insert pockets
can be identical. The
number (n) of insert pockets of the tool can be equal to a closest integer
resulting from dividing the
tool's cutting diameter, measured in millimeters, by 10.
YYY. A sum of first and second tool approach angles k2, k3 can be greater than
a sum of insert
ramping and approach angles kO, k 1 . It is believed that even though this
reduces a contact area
between the insert and the tool, such disadvantage is offset by allowing a
simpler insert
manufacturing process.
ZZZ. A tool assembly can preferably be configured for a depth of cut ap
fulfilling the condition
(1mm < ap < 2.5mm). It is believed better performance can be achieved with a
depth of cut ap
closer to 1.85mm. Accordingly, the depth of cut ap preferably fulfills the
condition (1.85mm
0.5mm). A preferred ratio of ap to length fulfills the condition (1:15 to
1:6).
In the specification hereinabove and below, a value followed by a range using
the symbol " ",
is to be considered to be an optimal value and values of the range closer to
the optimal value are
more preferred than values further therefrom.
It will be understood that all inserts mentioned in the specification and
claims are ramping
inserts, and that the word "insert" is occasionally mentioned without the
preceding word "ramping"
for conciseness only. Similarly, the words "high-feed milling tool" may appear
in the abbreviated
form of the word "tool" only.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the subject matter of the present application,
and to show how
the same may be carried out in practice, reference will now be made to the
accompanying drawings,
in which:
Fig. 1A is a perspective view of a tool assembly;
Fig. 1B is an end view of the assembly in Fig. 1A;
Fig. 1C is side view of the assembly in Figs. 1A and 1B, and is perpendicular
to a rake
surface of the ramping insert in the right corner of the figure (i.e., a view
along a rake axis of
that insert);
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Fig. 1D is side view of the assembly in Figs. 1A to 1C, and is rotated from
the view in Fig.
1C to be perpendicular to a side sub-surface of the ramping insert in the
middle of the figure;
Fig. 2A is a top view of a ramping insert of the face mill in Figs. lA to 1D;
Fig. 2B is a side view of the ramping insert in Fig. 2A;
Fig. 2C is front view of the ramping insert in Figs. 2A and 2B, this figure
can also be
considered as a view perpendicular to a rake surface (i.e. a view along a rake
axis);
Fig. 2D is a sectional view taken along line 2D-2D in Fig. 2A;
Fig. 2E is a sectional view taken along line 2E-2E in Fig. 2A;
Fig. 3A is a view showing a portion of the assembly in Fig. 1C;
Fig. 3B is a view corresponding the view in Fig. 3A, but showing the tool
only;
Fig. 3C is a sectional view taken along line 3C-3C in Fig. 3A;
Fig. 3D is a perspective view of an insert pocket of the tool shown in Fig.
3B;
Fig. 4A is a side view of the assembly in Figs. 1A to 1D performing a
shouldering operation
on a workpiece (i.e. removing material from the main surface but not the
adjacent step);
Fig. 4B is a side view of the assembly in Figs. 1A to 1D performing a combined
shouldering
and facing operation on a workpiece (i.e. removing material from both the main
surface and
the adjacent step);
Fig. 4C is a side view of the assembly in Figs. 1A to 1D performing a ramping
operation on
a partially shown main surface of a workpiece;
Fig. 4D is a side view of the assembly in Figs. 1A to 1D performing a plunging
operation on
a workpiece (yet unlike Figs. 4A to 4C this view does not show a chip);
Fig. 5A is a top view of another embodiment of a ramping insert;
Fig. 5B is a side view of the ramping insert in Fig. 5A;
Fig. 5C is front view of the ramping insert in Figs. 5A and 5B, this figure
can also be
considered as a view perpendicular to a rake surface (i.e. a view along a rake
axis); and
Fig. 5D is a similar view to Fig. 5C except that the ramping insert is
oriented in an operative
position relative to a workpiece surface.
DETAILED DESCRIPTION
Reference is made to Figs. 1A to 1D which illustrate a high-feed milling tool
assembly 10.
The assembly 10 can comprise a tool 12 and a ramping insert 14 (14A, 14B, 14C,
14D, 14E), and a
screw 16 for fastening each insert 14 to the tool 12.
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For a tool diameter DT of 50mm, the tool 12 and can have five inserts 14 as
shown.
A rotation axis AR can extend longitudinally through the center of the tool
12, and can
define a forward direction DF and a rearward direction DRE.
The tool 12 can be configured for rotating about the rotation axis AR in a
rotation direction
DRO.
Fig. 1C shows a tool plane Pm extending perpendicular to the rotation axis AR.
An outward
direction DOR extends parallel to the tool plane PTL and outward from the tool
12. An inward
direction DIR extends parallel to the tool plane Pm and inward into the tool
12. It will be understood
that the inward and outward directions are not precisely directed towards the
rotation axis AR, but
are generally directed towards and away from the center of the tool 12.
Referring now to Figs. 2A to 2E, the insert 14A will be described in more
detail. The inserts
shown can be identical and can be considered to have all features mentioned
hereinbelow in
connection with the insert 14A described.
The insert 14A is for metal machining operations and can be typically made of
extremely
hard and wear-resistant material such as cemented carbide. Preferably, the
insert 14A can be pressed
to final dimensions.
The insert 14A can comprise opposing first and second rake surfaces 18A, 18B
and an insert
peripheral surface 20 connecting the first and second rake surfaces 18A, 18B.
The insert 14A can be formed with an insert screw hole 22 opening out to
opposing sides
24A, 24B (Fig. 2E) of the insert peripheral surface 20.
A first cutting edge 26A can extend along an intersection of the insert
peripheral surface 20
and the first rake surface 18A.
A second cutting edge 26B can extend along an intersection of the insert
peripheral surface
20 and the second rake surface 18B.
The first and second cutting edges 26A, 26B can be identical and can be
considered to have
all features mentioned hereinbelow in connection with the other.
Also, the first and second rake surfaces 18A, 18B can be identical and can be
considered to
have all features mentioned herein below with the other.
The first cutting edge 26A can comprise a first ramping sub-edge 28A1; a first
side sub-edge
28B1; a first feed sub-edge 28C1 connected to the first ramping sub-edge 28A1
and first side sub-
edge 28B1; a second ramping sub-edge 28A2 connected to the first side sub-edge
28B1; a second
side sub-edge 28B2 connected to the first ramping sub-edge 28A1; and a second
feed sub-edge
28C2 connected to the second ramping sub-edge 28A2 and second side sub-edge
28B2.
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The first rake surface 18A can comprise a land 30 extending inwardly from the
first cutting
edge 26A.
Further inward of the land 30 can be a sloping portion 32 that extends between
the land 30
and a central rake surface region 34.
As shown best in Fig. 2C, the ramping and feed sub-edges converge with
increasing
proximity to the side sub-edge to which they are both connected. For example,
the first feed sub-
edge 28C1 is closer to the second ramping sub-edge 28A2 with increasing
proximity to the first side
sub-edge 28B1.
Referring to Fig. 2D, the insert 14A can comprise a rake axis AK extending
through a center
of, and perpendicular to, the first and second rake surfaces 18A, 18B (Fig.
2A).
A median length plane PL can bisect the first and second rake surfaces 18A,
18B along a
longitudinal dimension thereof. The median length plane PL can bisect the side
sub-edges 28B1,
28B2, 28B3, 28B4 (Figs. 2A, 2C).
A median thickness plane PT can extend perpendicular to the median length
plane PL and can
also bisect the first and second rake surfaces 18A, 18B.
Referring to Fig. 2A, a median height plane PH can extend perpendicular to the
median
length and thickness planes PL, PT and can also bisect the insert 14A.
A height axis AH can extend perpendicular to the rake axis AK and can extend
along an
intersection of the median thickness and height planes PT, PH.
As the insert screw hole can be in the center of the insert 14A, an insert
screw hole axis As
can be coaxial with the height axis AH.
The insert 14A can be configured for two indexable positions. For example, the
insert 14A
can be 180 rotationally symmetric about the rake axis AK.
The insert 14A can be configured to be reversed, allowing two additional
indexable
positions. For example, the insert 14A can also be 180 rotationally symmetric
about the screw hole
axis As and/or the height axis AFL
Referring to Fig. 2C, each ramping sub-edge 28A1, 28A2 can comprise a straight
portion
36S1, 36S2. Each ramping sub-edge 28A1, 28A2 can comprise a pair of corner
portions 36C1,
36C2, 36C3, 36C4 connected to each side of the straight portions 36S1, 36S2.
Each side sub-edge 28B1, 28B2 can comprise a straight portion 38S1, 38S2. Each
side sub-
edge 28B1, 28B2 can comprise a pair of corner portions 38C1, 38C2, 38C3, 38C4
connected to each
side of the straight portions 38S1, 38S2.
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Each feed sub-edge 28C1, 28C2 can comprise a straight portion 401, 40S2. Each
ramping
sub-edge 28C1, 28C2 can comprise a pair of corner portions 40C1, 40C2, 40C3,
40C4 connected to
each side of the straight portions 40S1, 40S2.
Each straight portion (36S1, 36S2, 38S1, 38S2, 40S1, 40S2) ends at
discontinuity points
(42D1, 42D2, 42D3, 42D4, 44D1, 44D2, 44D3, 44D4, 46D1, 46D2, 46D3, 46D4), i.e.
where the
edge transitions to extend in a different direction. Should the straight
portions be generally straight
but be slightly arched (at least relative to a theoretical straight line, but
still significantly less arched
than the corner portions) the discontinuity points are to be considered to
start where there is a visible
change in direction or gradient.
The straight portion 36S1 of the first ramping sub-edge 28A1 can have a length
Lsi.
The straight portion 38S1 of the first side sub-edge 28B1 can have a length
LS2.
The straight portion 40S1 of the first feed sub-edge 28C1 can have a length
LS3.
Each sub-edge can transition to an adjacent sub-edge at a connection point
bisecting a corner
formed by adjacent corner portions. For example, the first feed sub-edge 28C1
and first side sub-
edge 28B1 can connect at a first connection point X 1. The first connection
point X1 can be an equal
distance from the start of the straight portions 40S1, 38S1 of the first feed
sub-edge 28C1 and first
side sub-edge 28B1. Similarly, the first side sub-edge 28B1 and second ramping
sub-edge 28A2 can
connect at a second connection point X2. The second ramping sub-edge 28A2 and
the second feed
sub-edge 28C2 can connect at a third connection point X3. The second feed sub-
edge 28C2 and the
second side sub-edge 28B2 can connect at a fourth connection point X4. The
second side sub-edge
28B2 and the first ramping sub-edge 28A1 can connect at a fifth connection
point X5. The first
ramping sub-edge 28A1 and the first feed sub-edge 28C1 can connect at a sixth
connection point
X6.
An overall length of each sub-edge can be measured between the connection
points thereof.
For example, an overall length Loi of the first ramping sub-edge 28A1 can be
measured between the
connection points X5, X6 thereof. An overall length L02 of the first side sub-
edge can be measured
between the connection points X 1, X2 thereof. An overall length L03 of the
first feed sub-edge can
be measured between the connection points X6, X1 thereof.
The straight portion of the first ramping and feed sub-edges 36s), 40si can
have the same
length LS1, LS3. The ramping and feed sub-edges overall lengths L01, L03 can
also be the same
length.
The lengths of the second sub-edges 28A2, 28B2, 28C2 can be the same as those
of the
respective first sub-edge 28A1, 28B1, 28C1.
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The straight portions of the first and second ramping sub-edges 28A1, 28A2 can
be parallel.
The straight portions of the first and second side sub-edges 28B1, 28B2 can be
parallel.
The straight portions of the first and second feed sub-edges 28C1, 28C2 can be
parallel.
The third and sixth connection points X3, X6 can both lie on a median
thickness plane PT.
A maximum thickness TM of the insert 14 is shown in Fig. 2B. The maximum
thickness TM is
measurable parallel to the median thickness plane PT. For example, it can be
measured between the
third and sixth connection points X3, X6.
Reverting to Fig. 2C, a maximum rake surface length LMK is shown between
diametrically
opposed ends (e.g. 38C2, 38C4) of the straight portions 38S1, 38S2 of the
first and second side sub-
edges 28B1, 28B2.
A longitudinal rake surface length LLK on each rake surface can be measurable
parallel to the
median length plane PL.
The maximum rake surface length LMK can be slightly greater than the
longitudinal rake
surface length LLK. The longitudinal rake surface length LLK can also have a
greater length than
between any two other sub-edges (i.e. not between both side sub-edges 28B1,
28B2) of the first rake
surface 18A.
A maximum height HM of the insert 14 is shown in Fig. 2B. The maximum height
HM is
measurable parallel to the rake axis AK. For example, it can be measured in
the view shown in Fig.
2A, between point 48A (which is located at an intersection of the first
cutting edge 26A and the
median thickness plane PT in the view shown) and point 48B (which is located
at an intersection of
the second cutting edge 26B and the median thickness plane PT in the view
shown).
One successfully tested design has the following lengths: the length LS2 of
each side sub-
edge's straight portions can be lmm, and each overall length L02 can be
2.35mm; the length LS1, LS3
of each ramping and feed sub-edge's straight portion can be 6.5mm, and each
overall length L01,
L03 can be 7.8mm. The maximum thickness TM can be 6.35mm; the maximum rake
surface length
LIvIR can be 15.13mm; the longitudinal rake surface length LLK can be 15.10mm.
The maximum
height HM can be 9.5mm.
It will be understood that an insert according to the subject matter of the
present application
may be sized differently. Nonetheless, proportional length ratios to those
exemplified can be similar.
Referring to Figs. 2A to 2C, it will be understood that portions of the first
cutting edge 26A
can extend different amounts from the median height plane PH. For reference an
extremity plane PE
extending parallel to the median height plane PH and along an upper extremity
of the insert 14A in
Fig. 2B is shown.
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The straight portions 40S1, 40S2 of the feed sub-edges 28C1, 28C2 can extend
parallel to
the extremity plane PE.
At the discontinuity points 42D1, 42D3 where the ramping sub-edges 28A1, 28A2
transition from straight portions to corner portions, the first cutting edge
26A can be closest to the
median height plane PH. The general path of the first cutting edge 26A can be
as follows: as the first
ramping sub-edge 28A1 extends from the discontinuity point 42D1 to the sixth
connection point X6
it can extend further from the median height plane PH. From the sixth
connection point X6 until the
discontinuity point 46D2 the first feed sub-edge 28C1 can extend parallel to
the extremity plane PE.
As the first feed sub-edge 28C1 starts to curve at the corner portion 40C2
thereof, the first cutting
edge 26A can extend further towards the median height plane PH until it
reaches low discontinuity
point 42D3 of the second ramping sub-edge 28A2. From the discontinuity point
42D3 the first cutting
edge 26A can again extend further from the median height plane PH until
reaching the third
connection point X3 (Fig. 2C), etc.
In Fig. 2B, and best shown in Fig. 2E, the land 30 can form a land angle a
with the
extremity plane PE. The land angle a can be 6 10 . Such optional land is
believed to assist in
prolonging tool life for high-feed operations.
The insert peripheral surface 20 can comprise: a first ramping sub-surface
20A1; a first side
sub-surface 20B1; a first feed sub-surface 20C1 connected to the first ramping
sub-surface 20A1
and the first side sub-surface 20B1; a second ramping sub-surface 20A2 (Fig.
2D) connected to the
first side sub-surface 20B1; a second side sub-surface 20B2 connected to the
first ramping sub-
surface 20A1; and a second feed sub-surface 20C2 connected to the second
ramping sub-surface
20A2 (Fig. 2D) and second side sub-surface 20B2.
The first ramping sub-surface 20A1 can extend between opposing ramping and
feed sub-
edges. To elaborate, the first ramping sub-surface 20A1 can extend between the
first ramping sub-
edge 28A1 of the first cutting edge 26A and an opposing feed sub-edge 50C1 of
the second cutting
edge 26B. Similarly, the first feed sub-surface 20C1 can extend between
opposing ramping and feed
sub-edges 50A1, 28C1. It will be noted that the names "feed sub-surface" and
"ramping sub-
surface" do not necessarily indicate geometric differences. The second ramping
and feed sub-
surfaces extend in a similar manner.
The first side sub-surface 20B1 can extend between opposing side sub-edges
28B1, 28B3.
The second side sub-surface 20B2 can extend between the other side sub-edges
28B2, 28B4.
Referring to Fig. 2C, the first ramping sub-edge 28A1 can form an insert
ramping angle k0
with the median longitudinal plane PL The insert ramping angle k0 can be 15 .
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The first feed sub-edge 28C1 can form an insert approach angle k 1 with the
median
longitudinal plane PL The insert approach angle kl can be 15 .
Referring also to Fig. 2C, the insert screw hole 22 can open out partially to
each of the first
and second ramping and feed sub-surfaces 20A1, 20A2, 20C1, 20C2.
In the view of Fig. 2B, a minimum screw hole thickness Tsi of the insert screw
hole 22 is
shown. The screw hole thickness can increase to a maximum screw hole thickness
TS2 with
increasing proximity to each of the first and second rake surfaces 18A, 18B.
Reverting to Fig. 2D, the insert screw hole 22 can have a central constricted
portion 52
which increases in diameter with increasing proximity to the insert peripheral
surface 20. Slanted, or
more precisely frustoconical, screw abutment surfaces 54A, 54B can be located
between the central
constricted portion 52 and the insert peripheral surface 20.
Referring to Fig. 2E, each rake surface 18A, 18B can comprise a respective
rake abutment
surface 56A, 56B. Each rake abutment surface 56A, 56B can comprise first and
second rake
abutment sub-surfaces 56A1, 56A2, 56B1, 56B2 located on opposite sides of the
median length
plane PL.
Each rake abutment sub-surface can be slanted such that with increasing
proximity to the
median length plane PL there is greater extension from a median height plane
PH. For example, the
first rake abutment sub-surface 56A1 on the first rake surface 18A is shown
with a first random
location 58A close to the median length plane PL and a second random location
58B further
therefrom. As shown, the first location 58A is further from the median height
plane PH than the
second location 58B.
Referring to Fig. 3B, the tool 12 can comprise a tool end surface 60 and a
circumferentially
extending tool peripheral surface 62 extending rearward therefrom.
The tool 12 can further comprise a flute 64 formed at an intersection of the
tool end surface
60 and the tool peripheral surface 62 and extending rearward therefrom.
The tool 12 can further comprise an insert pocket 66 formed at an intersection
of the tool end
surface 60 and the tool peripheral surface 62, and opening out to the flute
64.
As the insert pockets 66 of the tool 12 can all be identical, reference will
be made to either of
the insert pockets 66 shown in Fig. 3B which show identical features from
different views.
Referring also to Fig. 3D, the insert pocket 66 can comprise a pocket side
surface 68, a
pocket back surface 70, a pocket top surface 72, and a threaded pocket screw
hole 73 opening out to
the pocket top surface 72.
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Noting the directions in Fig. 1B, it can be understood that: the pocket back
surface 70
extends inwardly (i.e. in the inward direction DiR) from the tool peripheral
surface 62 and faces the
rotation direction DRO (Fig. 1B); the pocket side surface 68 extends from the
pocket back surface 70
to the flute 64 and faces outwardly (i.e. in the outward direction DoR); the
pocket top surface 72
extends inwardly (i.e. in the inward direction DiR) from the tool peripheral
surface 62 to the pocket
side surface 68, and also extends from the pocket back surface 70 to the flute
64 (i.e. in the rotation
direction DRo).
The pocket side surface 68 can comprise a side abutment sub-surface 68A. The
side
abutment sub-surface 68A can extend perpendicular to the tool plane PTL (Fig.
1C).
The pocket back surface 70 can comprise a back abutment surface 70A.
The back abutment surface 70A can be formed with a back surface relief recess
70B dividing
the back abutment surface 70A into two back abutment sub-surfaces 70C, 70D.
Referring also to Fig. 3C, the back abutment surface 70A can be axially
located along at a
lower half of an insert pocket 66 (e.g., lower than a bisection plane PB which
extends perpendicular
to a pocket screw hole axis AB and bisects the insert pocket from a highest
point thereof, for
example a top surface relief recess 82, to the lowest point thereof, for
example the point designated
71 in Fig. 3C).
The back abutment sub-surfaces 70A, 70B can be slanted as shown. To provide an
anti-slip
effect, the back abutment sub-surface 70A, i.e. the back abutment sub-surfaces
70C, 70D thereof,
can be slanted relative to the insert 14A. This can be achieved, for example,
by slanting the back
abutment sub-surfaces 70C, 70D relative to the pocket screw hole axis AB. For
illustrative purposes
an additional axis AB1, which is parallel to the pocket screw hole axis AB, is
shown to show a back
abutment surface angle 0 relative to the pocket screw hole axis AB. The back
abutment surface angle
f3 can be 10 .
The pocket top surface 72 can comprise first and second pocket top sub-
surfaces 72A, 72B.
The first and second pocket top sub-surfaces surfaces 72A, 72B can be minor
symmetric on each
side of the pocket screw hole 73 (or more precisely minor symmetric about a
plane Ps (Fig. 3B)
bisecting the pocket screw hole 73 and extending perpendicular to the tool
plane PTL and along the
rotation direction). It can be understood that first and second pocket top sub-
surfaces surfaces 72A,
72B can extend an equal radial distance RD (i.e. in a direction basically
inward or outward of the
tool, i.e. along a plane perpendicular to a rotation axis of the tool).
The first pocket top sub-surface 72A is shown adjacent to the tool peripheral
surface 62 and
extends more in the forward direction DF with increasing proximity to the tool
peripheral surface 62.
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For example, a first random location 74A on the first pocket top sub-surface
72A is closer to tool
peripheral surface 62 than a second random location 74B. As shown, the first
location 74A extends
further in the forward direction DF than the second random location 74B.
By contrast, the second pocket top sub-surface 72B (shown in Fig. 3B with a
phantom line)
can be adjacent to a pocket side surface 68 and extends more in the forward
direction DF with
increasing proximity thereto.
The first and second pocket top sub-surfaces 72A, 72B can extend more in the
forward
direction DF with increasing proximity to the flute 64. For example, a third
random location 76A on
the first pocket top sub-surface 72A (and directly adjacent the tool
peripheral surface 62) is closer to
the flute 64 than a fourth random location 76B (also directly adjacent to the
tool peripheral surface
62). As shown, the third location 76A extends further in the forward direction
DF than the fourth
random location 76B.
Further, the first pocket top sub-surface 72A can form an internal acute first
tool angle k2
with a plane Pc that extends perpendicular to the rotation axis AR. The first
tool angle k2 can be
15.5 .
In the same view, the second pocket top sub-surface 72B can form an internal
acute second
tool angle k3 with the plane Pc. The second tool angle k3 can be 15.5 .
A sum of first and second tool approach angles k2, k3 (e.g., 31 ) can be
greater than a sum of
insert ramping and approach angles kO, k 1 (e.g., 30 ). Alternatively stated,
an external tool angle El
(Fig. 3B), e.g. 149 , can be smaller than an internal insert angle E2 (Fig.
2C), e.g. 150 .
As a result, the insert peripheral surface 20, and more precisely the ramping
and feed sub-
surfaces (e.g., 20A1, 20C1) thereof are only configured for limited contact
with the first and second
pocket top sub-surfaces 72A, 72B. To elaborate, areas of the insert pocket 66
configured to abut the
insert are shown as shaded regions in Fig. 3D. Notably, there are first and
second theoretical contact
lines 72C, 72D on the first and second pocket top sub-surfaces. These lines
indicate regions of the
insert 14A and the pocket top surface 72 which are configured to abut. It will
be understood that
because the sum of the tool angles (i.e., first and second tool approach
angles k2, k3) are larger than
the sum of the insert angles (i.e., insert ramping and approach angles kO,
k1), then contact between
the corresponding surfaces of each will be limited and not extend over the
entire first and second
pocket top sub-surfaces 72A, 72B. Even though larger contact areas are
generally preferred, by
having different angles less precision is required for insert manufacture,
which is beneficial when
pressing an insert to final dimensions.
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By contrast, the other shaded regions shown 68A, 70C, 70D are visibly
delimited sub-
surfaces of the insert pocket 66.
The screw 16 can comprise a screw head 16A and an externally threaded shank
16B
extending therefrom.
When the screw 16 secures the insert 14A to the insert pocket 66, as shown in
Fig. 3C, the
shank 16B is threadingly fastened to the pocket screw hole 73 and the screw
head 16A abuts one of
the screw abutment surfaces 54A of the ramping insert 14A.
The insert 14A and tool 12 are configured for contact of only the insert's
insert peripheral
surface 20 with the tool's pocket side surface 68 and first and second pocket
top sub-surfaces 72A,
72B, and abutment of one of the ramping insert's rake surfaces 18B with the
tool's pocket back
surface 70.
More precisely, the insert 14A and tool 12 are configured for contact of only:
the second
side sub-surface 20B2 with the side abutment sub-surface 68A; the second
ramping sub-surface
20A2 with the first pocket top sub-surface 72A; the second feed sub-surface
20C2 with the second
pocket top sub-surface 72B; and the second rake surface 18B with the back
abutment surface 70A.
More precisely, the second ramping sub-surface 20A2 can contact the first
theoretical
contact line 72C of the first pocket top sub-surface 72A, and the second feed
sub-surface 20C2 can
contact the second theoretical contact line 72D of the second pocket top sub-
surface 72B.
Further, more precisely, exactly one of the rake abutment sub-surfaces 56B2
can contact
both of the back abutment sub-surfaces 70C, 70D.
To ensure contact at the desired portions only, the insert pocket 66 can be
formed with
relief portions. To simplify insert manufacture, all the relief portions of
the assembly 10 can be
formed on the tool 12.
For example, the pocket back surface 70 can have the above-mentioned back
surface relief
70B. Referring briefly to Fig. 2C, it is noted that consequently a central
portion 78 of the first rake
surface 18A, which lies along the median thickness plane PT will not contact
the pocket back surface
70 (since it will be adjacent the back surface relief 70B). However, first and
second abutment
portions 80A, 80B of the first rake surface 18A which are located on opposing
sides of the central
portion 78 will each respectively contact one of the back abutment sub-
surfaces 70C, 70D.
The pocket top surface 72 can be formed with the top surface relief recess 82
located
between first and second pocket top sub-surfaces 72A, 72B.
To further achieve desired contact, a lower relief region 84 can be formed
underneath the
back abutment surface(s) 70. Additionally, an upper relief region 86 can
separate the pocket back
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and top surfaces 70, 72. Similarly, a first side relief region 88 can separate
the pocket side and back
surfaces. Similarly, a second side relief region 90 can separate the pocket
side and top surfaces 68,
72.
Drawing attention to Figs. 4A to 4D and Fig. 2C, it will be noted that the
assembly 10 can
carry out a number of different machining operations on a workpiece 92.
The shouldering operation shown in Fig. 4A is carried out by moving the
assembly 10 in a
sideways direction Dsi which is perpendicular to a lower surface 92A of the
workpiece 92 being
machined. As the assembly 10 is still spaced apart from an upwardly extending
step 92B of the
workpiece 92, and more precisely an upwardly projecting side surface thereof
92C, only the first
feed sub-edge 28C1 of the insert 14A removes material from the workpiece 92.
This is
schematically shown by a chip 94A being removed by the first feed sub-edge
28C1 and flowing
above the first rake surface 18A. Notably, the assembly 10 can remove material
to a depth of cut ap,
shown in Fig. 1C. It will also be noted that the material removal can be
carried out with a
comparatively long portion of the cutting edge. More precisely, this operation
can be carried out
with a portion of the first cutting edge 26A extending from the sixth contact
point X6 to the end of
the straight portion 40S1 of the first feed sub-edge 28C1, namely the
discontinuity point designated
46D2.
In Fig. 4B a combined shouldering and facing operation is shown, and is also
carried out by
also moving the assembly 10 in the sideways direction Dsi. The assembly 10 can
simultaneously
remove material from the adjacent step 92B, and more precisely the side
surface 92C thereof, as
well as from the lower surface 92A of the workpiece 92. This is schematically
shown by a chip 94B,
of different shape to the chip 94A in Fig. 4A, being removed by both the first
feed sub-edge 28C1
and the first side sub-edge 28B1. It will also be noted that the material
removal can be carried out
with a comparatively long portion of the cutting edge. More precisely, this
operation can be carried
out with a portion of the first cutting edge 26A extending from the sixth
contact point X6 to the end
of the straight portion 38S1 of the first side sub-edge 28B1, namely the
discontinuity point
designated 44D2.
A ramping operation is shown in Fig. 4C, in which the assembly 10 moves
simultaneously
in both a sideways direction DS2 and the forward direction DF. Stated
differently, the assembly 10
moves in a sideways-forward direction DSF. During this motion, the first
ramping sub-edge 28A1
removes material from the workpiece 92, schematically shown by a chip
designated 94C. It will be
noted that the insert 14A is capable of removing a comparatively large chip
during ramping, due to
the comparatively large ramping sub-edge thereof. It will also be noted that
the material removal can
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be carried out with a comparatively long portion of the cutting edge. More
precisely, this operation
can be carried out with a portion of the first cutting edge 26A extending from
the sixth contact point
X6 to the end of the straight portion 36S1 of the first ramping sub-edge 28A1,
namely the
discontinuity point designated 42D1.
A plunging operation is shown in Fig. 4D, in which the assembly 10 moves in
the forward
direction DF. During such motion, each of the first side sub-edge 28B1, the
first feed sub-edge 28C1
and even the first ramping sub-edge 28A1, if there is material thereunder, can
removes material
from the workpiece 92. While the comparatively large insert ramping and
approach angles kO, k 1
may reduce surface finish, this may be offset by ramping and feed operation
capability. It will also
be noted that the material removal can be carried out with a comparatively
long portion of the
cutting edge. More precisely, this operation can be carried out with a portion
of the first cutting edge
26A extending from the end of the straight portion 38s1 of the first side sub-
edge 28B1, namely the
discontinuity point designated 44D2, to the end of the straight portion 36S1
of the first ramping sub-
edge 28A1, namely the discontinuity point designated 42D1.
Referring now to Figs. 5A to 5C, alternative insert features will be shown.
Except where explicitly stated or clearly shown, said features of an
exemplified insert 114A
should be considered to correspond to the previously described insert 14A.
The insert 114A can comprise opposing first and second rake surfaces 118A,
118B and an
insert peripheral surface 120 connecting the first and second rake surfaces
118A, 118B.
The insert 114A can be formed with an insert screw hole 112 opening out to
opposing sides
of the insert peripheral surface 120.
A first cutting edge 126A can extend along an intersection of the insert
peripheral surface
120 and the first rake surface 118A. A second cutting edge 126B can extend
along an intersection
of the insert peripheral surface 120 and the second rake surface 118B.
The first and second cutting edges 126A, 126B can be identical and each can be
considered
to have all features mentioned hereinbelow in connection with the other.
Also, the first and second rake surfaces 118A, 118B can be identical and each
can be
considered to have all features mentioned herein below with the other.
The first cutting edge 126A can comprise a first ramping sub-edge 128A1; a
first side sub-
edge 128B1; a first feed sub-edge 128C1 connected to the first ramping sub-
edge 128A1 and first
side sub-edge 128B1; a second ramping sub-edge 128A2 connected to the first
side sub-edge
128B1; a second side sub-edge 128B2 connected to the first ramping sub-edge
128A1; and a second
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feed sub-edge 128C2 connected to the second ramping sub-edge 128A2 and second
side sub-edge
128B2.
The first rake surface 118A can comprise a land 130 extending inwardly from
the first
cutting edge 126A.
Further inward of the land 130 can be a sloping portion 132 that extends
between the land
130 and a central rake surface region 134. One difference from the above
described first
embodiment insert 14A is that each central rake surface region 134 of the
second embodiment insert
114A may be planar.
As shown best in Fig. 5C, the ramping and feed sub-edges 128A1, 128A2, 128C1,
128C2
converge with increasing proximity to the side sub-edge 128B1, 128B2 to which
they are both
connected. For example, the first feed sub-edge 128C1 is closer to the second
ramping sub-edge
128A2 with increasing proximity to the first side sub-edge 128B1.
The insert 114A can comprise a rake axis AK extending through a center of, and
perpendicular to, the first and second rake surfaces 118A, 118B (Fig. 5C).
A median length plane PL (Fig. 5B) can bisect the first and second rake
surfaces 118A, 118B
along a longitudinal dimension thereof.
A median thickness plane PT (Fig. 5A and 5C) can extend perpendicular to the
median length
plane PL and can also bisect the first and second rake surfaces 118A, 118B.
Alternatively defined
the median thickness plane PT can contain the rake axis AK and can also bisect
the first and second
rake surfaces 118A, 118B
Referring to Fig. 5A, a median height plane PH can extend perpendicular to the
median
length and thickness planes PL, PT and can also bisect the insert 114A while
being equally spaced
from the first and second side sub-edges 128B1, 128B2.
A height axis AH can extend perpendicular to the rake axis AK and can extend
along an
intersection of the median thickness and height planes PT, PH.
The insert screw hole 122 can be in the center of the insert 114A, and an
insert screw hole
axis As can be, in this non-limiting example, coaxial with the height axis AH.
The insert 114A can be configured for two indexable positions on the first
rake surface
118A. To elaborate, the insert 114A can be rotated about the rake axis AK to
bring it to a second
indexable position. For example, the insert 114A can be 180 rotationally
symmetric about the rake
axis AK.
The insert 114A can alternatively or preferably additionally, also be
configured to be
reversed, allowing two additional indexable positions on the second rake
surface 118B. For
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example, the insert 114A can also be 1800 rotationally symmetric about an axis
that lies along the
intersection of the median height and thickness planes PH, PT, which in this
example corresponds to
the height axis AFL
Referring to Fig. 5C, each ramping sub-edge 128A1, 128A2 can comprise a
straight portion
136S1, 136S2. Each ramping sub-edge 128A1, 128A2 can also comprise a pair of
corner portions
136C1, 136C2, 136C3, 136C4 connected to each side of the straight portions
136S1, 136S2.
Each side sub-edge 128B1, 128B2 can comprise a straight portion 138S1, 138S2.
Each side
sub-edge 128B1, 128B2 can also comprise a pair of corner portions 138C1,
138C2, 138C3, 138C4
connected to each side of the straight portions 138S1, 138S2.
Each feed sub-edge 128C1, 128C2 can comprise a straight portion 140S1, 140S2.
Each feed
sub-edge 128C1, 128C2 can comprise a pair of corner portions 140C1, 140C2,
140C3, 140C4
connected to each side of the straight portions 140S1, 140S2.
Each straight portion (136S1, 136S2, 138S1, 138S2, 140S1, 140S2) ends at
discontinuity
points (142D1, 142D2, 142D3, 142D4, 144D1, 144D2, 144D3, 144D4, 146D1, 146D2,
146D3,
146D4), i.e. where the edge transitions to extend in a different direction.
The second embodiment insert 114A differs from the previously described first
embodiment
insert 14A in that the corner portions connecting the ramp and feed sub-edges
are not curved but are
sharp corner portions (whereas first embodiment insert 14A exemplifies an
insert with all the corner
portions being curved).
To elaborate, the first ramping sub-edge 128A1 comprises the sharp ramp corner
portion
136C2 and the first feed sub-edge 128C1 comprises the sharp feed corner
portion 140C1. A
connection point X6 is located between the adjacent sharp corner portions
136C2, 140C1.
Drawing attention to Fig. 5D, elaborating by way of example with regard to one
of the feed
corner portions 140C1 and the adjacent ramp corner portion 136C2, it is shown
that both have sharp
shapes or, stated differently, sharp corner edges. This results in a straight
extension 139. Stated
differently, a straight extension 139 can extend between the adjacent ramp and
feed discontinuity
points 142D2, 146D1. The straight extension 139 has, as shown, a length that
is shorter that any of
the associated ramping and feed edges 128A1, 128C1.
An insert comprising such straight extension 139 (or, alternatively stated,
comprising sharp
adjacent feed and ramp corners) can be oriented as shown with the straight
extension 139 being
parallel, or substantially parallel, to the surface 137 being machined. It
will be understood that the
internal angles formed with the straight extension 139 and the adjacent first
ramping sub-edge
128A1 can be calculable (for the purposes of the present claims). Such
statement also applying to
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the straight extension 139 and the adjacent first feed sub-edge 128C1, as well
as to the other straight
extensions.
To elaborate, it will also be noted that a first internal angle R1 formed
between the straight
extension 139 and the adjacent first ramping sub-edge 128A1 is different, i.e.
not equal, to a second
internal angle R2 formed between the straight extension 139 and the adjacent
first feed sub-edge
128C1. More precisely, both the first and second internal angles R1, R2 are
less than 1800. The first
internal angle R1 is, in this non-limiting example, is 171 . The second
internal angle R2, in this non-
limiting example, is 163 . It will be understood that these angles can vary
but preferably result in
the straight extension 139 being parallel with the surface 137 being machined.
It will thus also be
understood that such angles are related to the insert ramping and approach
angles kO, k 1 and can be
calculable therefrom. Preferably, the straight extension 139 can be oriented
such that the feed corner
portion 140C1 is slightly further than the ramp corner portion 136C2 from the
surface 137 (even
though the difference is an amount measured in microns, preferably between 5
to 25 microns, and
hence is not visible at this magnification, and could also therefore be
considered parallel or
substantially parallel).
As the insert 114A is moved in the sideways direction Dsi the finish of the
surface 137 can
be slightly improved.
Nonetheless, it will be noted that such inserts and tools are intended for
high-feed operations
(noting that also the previously described first embodiment insert could
alternatively be provided
with sharp adjacent feed and ramp corners, without any other modifications
needed) and therefore
the surface finish may still be far inferior to inserts and tools intended for
non-roughing operations.
It will also be noted that providing sharp edges could also be expected to
provide inferior
tool life. Nonetheless, the slight improvement in finish is believed to offset
any possible
disadvantage of tool life.
Finally, it is noted that by utilizing sharp corner portions, the feed and
ramp sub-edges have
not been shortened. Preferably the straight extension 139 has a length between
0.5mm to 2.0mm.
Values closer to 0.5mm are preferred for the abovementioned reason.
As shown in the drawings, compared to the first embodiment insert 14A, the
currently
exemplified second embodiment insert 114A has longer feed sub-edges than
ramping edges. This
helps increase cutting depth to compensate for a smaller tool diameter (not
shown, in particular for
tool diameters of 32mm and, preferably, even smaller) for which the
exemplified second
embodiment insert 114A is designed. Nonetheless, such design can also be
utilized for larger
diameters as well, if desired.
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It will be understood that an insert resembling the previous first embodiment
insert 14A
could be modified to have sharp corner portions at adjacent ramp and feed sub-
edges thereof, and
could have equal length or different length ramp and feed sub-edges, since the
corner portion shape
and sub-edge lengths are independent of each other.
Similar to the previously described first embodiment insert 14A, the straight
portions of the
sub-edges can be parallel. However, as shown e.g. in Fig. 5C, since the feed
and ramp sub-edges
have unequal length, the first and second cutting edges 126A, 126B may be
slightly out of phase
with each other. A similar consequence is shown in Fig. 5A by way of minor
distortions 148A,
148B, 148C, 148D in otherwise planar portions of the peripheral surface 120.
Nonetheless, such
unequal lengths complicate manufacture, which has resulted in a split die
manufacturing design,
resulting in the parting lines 150A, 150B seen in Fig. 5A, and visible on the
peripheral surface 120
of the cutting insert 114A.
One example set of relative dimensions can be as follows: the length of each
side sub-edge's
straight portion can be 0.45mm; the length of each ramping feed sub-edge's
straight portion can be
2.5mm; the length of each feed sub-edge's straight portion can be 3.6mm. A
distance between the
discontinuity points 146D1, 142D2 can be 0.6mm. A radius curvature of the
corner between the
straight portions of the side sub-edge and ramping sub-edge can be 0.85mm, and
a radius curvature
of the corner between the straight portions of the side sub-edge and feed sub-
edge can be 1.00 mm.
Yet a further point of difference, shown in Figs. 5A and 5B, can be that the
exemplified
cutting edges 126A, 126B can each lie in a single plane, rather than
comprising portions being
different distances from the height plane PH.
Referring to Fig. 5D, as the insert will be oriented in a non-parallel manner
to a workpiece,
the following angles will be made with reference to the workpiece surface 137.
The first ramping
sub-edge 128A1 can form an insert ramping angle k0 with the surface 137 of 9 .
The first feed sub-
edge 128C1 can form an insert approach angle k 1 with the surface 137 of 17 .
Stated differently, the
insert approach angle k 1 is approximately twice the angular extension of the
insert ramping angle
kO. Preferably, the insert approach angle k 1 is within the range 17 3 .
The description above includes an exemplary embodiment and details, and does
not
exclude non-exemplified embodiments and details from the claim scope of the
present application.
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