Note: Descriptions are shown in the official language in which they were submitted.
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ROUGHING AND FINISHING
FACE MILLING CU'l"l'~;K AND INSERT
This invention relates to a face milling
cutter for the simultaneous rough and finish ma~h;n;ng
of a workpiece using identical inserts in the roughing
and f;~;ch;ng stations of the cutter body, and to the
on-edge cutting insert whose unique configuration makes
it possible to index the same individual insert to
present four different cutting edges for finish
10 mach;n;ng and four different edges for rough mach;n;ng,
to permit the same insert to be used for f;n; ch; ng and
then for roughing, or vice versa.
BACKGROUND OF ~HE lN V~ ON
While combination roughing and f;n;~h;ng face
milling cutters, as such, are known, the indexable
inserts employed in the roughing and f; n; ~h; ng stations
of the cutter body have been entirely different from one
another, and typically employed at a ratio of one
f; n; ~h;ng insert to from four or six roughing inserts.
The maintenance of the cutting efficiency of such
cutters requires that two kinds of inserts be inven-
toried, and in very different quantities of roughing and
f; n; sh; ng inserts, in order to maintain the service-
ability of the cutter. This presents problems of
inventory control and cutter management in production
macl. . n, ng, -which is the ob~ectlve of the cutter and
insert of this invention to eliminate while at the same
time doubling the service life of each individual insert
in the same cutter body, independent of the direction of
rotation of the cutter.
SUMMARY OF THE I~v~llON
The foregoing objective is attained by the
invention in the provision of a face milling cutter body
~ with alternately occurring stations, on the cutter
periphery for roughing and on the face of the cutter for
f;n;sh;ng, respectively, both stations employing iden-
tical inserts, which are of generally parallelepipedform having specially configured, oppositely facing
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cutting faces. When emplaced in a roughing station, the
insert is positioned generally vertically, or nearly so,
and the same or an identical insert when emplaced in a
f;n;ch;ng station is approximately horizontal, which is
5 to say that it sweeps in a plane perpendicular to the
cutter axis as the cutter rotates. The inserts of the
two kinds of cutting stations sweep paths which overlap
in part, allowing the f;n;~h;ng insert to share a
portion of the rough cutting load.
The configuration of the cutting faces of the
insert provides an edge-sharpening chip groove about
the periphery of the cutting face, which is generally
rectangular with radiussed corners, leaving a central
land to serve the load transfer function when the insert
15 is indexed to exchange cutting faces. The longer
cutting edges of each cutting face are preferably ground
with a mild arc to aid their finish milling function, as
will become apparent. The net result is that each
insert can be used eight times, four for roughing and
four for f;n;ch;ng, without any intermediate grinding.
DESCRIPTION OF THE DRAWINGS
The invention is described in detail below
with reference to one embodiment that is illustrated in
the drawings, in which:
FIGURE 1 is a facial elevation of the milling
cutter according to the invention;
FIGURE 2 is a side view of the milling cutter
according to FIG. l;
FIGURE 3 is an enlarged perspective represen-
30 tation of an indexable insert that essentially is
rectangular on all sides and can be arranged on the face
as well as the outer circumferential surface of a
surface milling cutter according to FIGS. l and 2;
FIGURE 4 is a section through the indexable
35 insert according to FIG. 3 along the line IV-IV;
FIGURE 5 is a view in the direction of the
arrow V in FIG. 3;
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FIGURE 6 is a view of the indexable insert
a~cording to FIG. 3 in the direction of the arrow VI;
D FIGURE 7 is a simplified schematic representa-
tion of the arrangement of an indexable insert on the
outer circumferential surface of the cutter body for
roughing;
FIG. 8 is a simplified schematic representa-
tion of the arrangement of an indexable insert on the
face of the cutter body for f;n;sh;ng; and
FIG. 9 is a schematic representation of the
indexable inserts, in both stations, one for roughing
according to FIG. 7 and one for f;n;ch;ng according to
FIG. 8, on the cutter body of a surface milling cutter
according to FIGS. 1 and 2, in which inserts of adjacent
15 roughing and f;n;~h;ng stations are shifted into a
common radial plane.
DE~ATT~n DESCRIPTION OF THE lNv~Nl~lON
FIGS. 1 and 2 show a face milling cutter 1 in
accordance with the invention. A number of cutting
20 inserts in the form of an indexable insert 3 (FIG. 3),
are arranged on the periphery of the disk-shaped cutter
body 2 and on the face 4 of the cutter body adjacent the
periphery, such that they can be removed, e~r-hAnged,
and/or transposed.
The cutter body 2 is equipped with indexable
inserts 3a at least within the circumferential region of
its face 4. Each of these inserts 3a is oriented with
its fi n;~:h; ng edge essentially in a plane perpendicular
to the rotational axis 5-5 of the milling cutter 1.
The placement of the indexable inserts 3a
on the face 4 of the cutter body 2 is such that their
active cutting edges are able to remove metal radially
as well as axially as the milling cutter 1 acts upon a
workpiece.
Each indexable insert 3a is accommodated in a
pocket 6 arranged in the face 4 of the cutter body 2, as
shown in FIG. 2. Each of these pockets 4 includes a
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base seat 7, a rear seat 8, and a lateral seat 9. The
re-lative arrangement of the base seat 7 and the longi-
tudinal seat 8 of the pockets 6 is shown in FIG. 2. The
relative arrangement of the rear seat 8 and the lateral
seat 9 is shown in FIG. 1.
The base seat of each pocket 5 in the face 4
of the cutter is inclined relative to the rotational
plane 10-10 of the cutter face 4 being closer to the
plane of the face in the advancing direction of rota-
10 tion, with said incline defining the clearance angleof the indexable inserts 3a emplaced therein. The
orientation and arrangement of the rear seat 8 and the
lateral seat 9 relative to the base seat 7 is determined
by the basic shape of the indexable inserts 3 used.
FIG. 1 additionally shows that each ;n~e~hle
insert 3a is fixed in its pocket 6 on the face 4 of the
cutter body 2 by means of a single ret~;n;ng screw 11,
preferably with countersink head that engages a counter-
sunk hole centrally of said indexable insert, permitting
20 the insert to be indexed or removed.
As the milling cutter 1 shown in FIGS. 1 and 2
is used as a face milling cutter for roughing as well as
for f;n;~h;ng the residual workpiece surface left by
roughing, the cutter body 2 is additionally equipped
25 with indexable inserts 3b on its outer peripheral
surface 12.
In contrast to the indexable inserts 3a
arranged on the face 4 of the cutter carrier base 2,
the indexable inserts 3b on the outer peripheral surface
30 12 of said cutter body are oriented essentially parallel
to the rotational axis 5-5 of the cutter body, i.e.,
essentially vertically as shown in FIG. 2.
The indexable inserts 3b arranged on the outer
periphery 12 of the cutter body 2 are uniformly distri-
35 buted circumferentially, as are also the indexableinserts 3a on the face 4 of the cutter.
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Each peripheral insert 3b also is mounted in a
pocket 13 milled in the outer peripheral surface 12 of
the cutter body 2, and defined by a base seat 14, a
longitll~; n~1 rear seat 15 and an upper seat 16. In the
pockets 13, the base seat 14 has a forwardly leaning
inclination relative to the cutting direction, with said
inclination defining the clearance angle behind the
lower cutting, or "wiping", edge 31 (FIG. 3) of the
indexable insert 3b.
A prominent feature of the milling cutter 1
according to FIGS. 1 and 2 is the fact that the pockets
6 and 13 for accommodating the identical indexable
inserts 3a and 3b are both disposed in the peripheral
region of the cutter body 2, and are distributed
uniformly and alternately on its face 4 and its outer
peripheral surface 12. This means that each indexable
insert 3b on the outer peripheral surface 12 of the
cutter body occurs between two adjacent indexable
inserts 3a on the face of said cutter carrier base 2,
20 and vice versa. That is to say, one half of the cutting
stations of the milling cutter 1 are arranged on the
face 4 of the cutter body 2, with the other half of said
cutting stations being arranged on the outer peripheral
surface 12.
This special arrangement is made possible by
an insert of novel configuration which allows it to
serve effectively either as insert 3a or 3b. Conse-
quently, only one type of indexable insert 3 is required
to service the cutter. One such indexable insert 3 is
30 shown in FIGS. 3-6.
Each indexable insert 3 according to FIGS. 3-6
is essentially a rectangular parallelepiped in overall
shape with two outwardly facing major lateral surfaces
21 and 22 that are parallel to one another, a bottom
35 surface 23 and a top surface 24 that are also parallel
to one another, as well as two outwardly facing,
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parallel end surfaces 25 and 26, as shown in detail in
FI-GS. 4-6.
To adapt the insert for the sharing of the
radial, rough-cutting load, the corners at which the
respective lateral surfaces 21 and 22 converge with the
end surfaces 25 and 26 of the insert 3, are rounded off
at 27, as shown in FIGS. 3-6. A hole 28 that extends
perpendicularly through the center of the lateral
surfaces 21 and 22 is arranged in each indexable insert
10 3, and is countersunk at 29 to receive the previously
mentioned countersink head retA;ning screws 11 for
fastening the ;n~Y~hle inserts 3 in their respective
pockets.
The indexable inserts 3 shown in FIGS. 3-6
have a configuration such that each insert can be
mounted on a milling cutter 1 of the type described in
eight different positions before the cutting edges of
said indexable insert must be resharpened, or the insert
discarded. Each insert 3 in accordance with FIGS. 3-6
can be arranged on the face 4 of the cutter body 2 in
four different installation positions as a f;n;~h;ng
insert 3a, or arranged on the outer circumferential
surface 12 of the cutter carrier base 2 in four
different installation positions as a roughing insert
3b. Consequently, a milling cutter 1 according to
FIGS. 1 and 2, which is provided with indexable inserts
3 according to FIGS. 3-6, has a significantly increased
service life and value.
The indexable inserts 3 according to FIGS. 3-6
have four long cutting edges 30, two of which extend
along the longitudinal edges of the major surfaces 21,
and the other two of which extend along the longitn~;n
edges of the opposite major surface 22. In this case,
each of the long cutting edges 30 does not have an
36 absolutely linear shape, but rather a slightly arcuate
contour as shown in FIG. 3.
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Four additional short cutting edges 31 of
linear shape extend, respectively, along the two end
surfaces 25 and 26, perpendicular to the cutting edges
30, and occur in pairs as the edges of the end surfaces
25 and 26.
In addition, each indexable insert 30 is
equipped with eight cutting edges 32 that extend in the
shape of a quarter circle, with each of said cutting
edges ext~n~;ng along a transition radius 27 from one of
10 the lateral surfaces 21 or 22 to one of the end surfaces
25 and 26.
Two long cutting edges 30 with the arc-shaped
contour and two short linear cutting edges 31, as well
as the four connecting, rounded, corner cutting edges
32, frame the bottom surface 23 and the top surface 24
of the insert.
All of the cutting edges 30, 31, and 32 have
positive rake angles, resulting from chip grooves 33
that are arranged in the bottom surface 23 and the top
20 surface 24, inwardly of the cutting edges. Identical
chip grooves 34 are also arranged in the bottom surface
23 and the top surface 24 along the end cutting edges
31. Within the region of the transition radii 27, the
chip grooves 33 and 34 run together to ensure that the
25 cutting edges 32 at this location, in the shape of a
quarter circle, also have a positive rake angle.
FIG. 7 shows that the indexable inserts 3b are
arranged on the outer circumferential surface 12 of the
cutter body 2 to position circular cutting edge 32
either as the main roughing edge, or as the lower
extremity of the main roughing edge, depen~;ng on the
depth of cut. In either case, the adjacent short
cutting edge 31 forms a secondary bottom cutting edge
because the indexable insert 3b is mounted essentially
35 vertically on the cutter body 2.
FIG. 8 shows a cutting edge 32 that is
curved in the shape of a circular arc and acts as a
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supplemental roughing edge on the indexable inserts 3a
arranged on the face 4 of the cutter body 2, i.e., the
f;n;5h;ng inserts that are essentially parallel to the
rotational plane lO-10 of the milling cutter 1. In this
5 case, a linear cutting edge 30 contiguous with the c
radially outermost circular cutting edge 32 is active
on the workpiece surface, making a f;n;ch;ng cut.
As each indexable insert 3 according to FIGS.
3-6 provides four sets of cutting edges 30, 31, and 32
10 when installed as an ;n~P~hIe insert 3a according to
FIGS. 1, 2, and 8, and four different sets of cutting
edges 30, 31, 32 when installed as an indexable insert
3b according to FIGS. 1, 2, and 7, one can appreciate
that each indexable insert 3 of the type shown in FIGS.
15 3-6 can be used in eight different installation
positions on one and the same cutter body 2 without
requiring resharpening, resulting in a distinct increase
of the entire service life of the insert.
That is to say, irrespective of the direction
20 of rotation of the cutter, each insert can be used in
eight different indexes, four in the 3b peripheral
roughing position and four in the 3a face or f;n;~h;ng
position.
More specifically, in the 3b peripheral
25 position, referring to FIG. 7, the lower right and the
upper left corners of the cutting face presented in that
view are interchangeable in that position to provide
two roughing cutting edges. Moreover, if the active
cutting face shown in FIG. 7 is interchanged with its
30 rearwardly-facing opposite face, two additional
diagonally opposite corners of the latter face are
available for roll~h;~, making a total of four.
That same insert remains available to present
two pristine diagonally opposite cutting edges 32, 30 in
35 the 3a position of FIG. 8, namely those which were the
upper outermost and lower innermost in FIG. 7, and two
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additional pristine edges of the same kind by turning
the insert front for back in the FIG. 8 position.
Moreover, the symmetry of each cutting face 23
and 24 of the insert about mutually perpendicular axes,
5 assures the availability of that versatility in either
direction of rotation for which a given cutter body may
be designed, making this cutter-insert combination
particularly desirable for use in transfer line
marh;~;ng where opposite rotation of cutters for the
10 simultaneous milling of surfaces on opposite sides of a
workpiece are encountered.
The insert of the invention, being identical
in its opposite cutting faces 23 and 24, is well adapted
for opposed-plunger molding to form the somewhat
15 intricate cutting faces 23 and 24, as well as the
exterior shape, in the "green" carbide hard metal before
sintering. After sintering, the insert may be chucked
by its cutting faces for any form grinding of the major
surfaces, end surfaces, and radiussed corners that may
20 be desired, as well as for the arc-grinding of the
linear cutting edges 30, earlier referred to.
The purpose of such arc-grinding of the linear
edges 30 is to equip them to better serve their finish-
ing function in the 3a insert position of FIG. 8. That
25 is, when the insert in a 3a inclined pcoket is viewed
head on, the convex curvature imparted to the cutting
edge 30 by the arc-grind projects as a shallow ellipse
when viewed from the front. The curvature is slight and
not shown as such in FIG. 8 (but see FIGS. 3 and 5) and
serves to feather the chip taken by f;n;sh;ng edge 30,
as disclosed in U.S. Patent 3,762,005-Erkfritz for the
advantageous purpose disclosed therein.
Not previously mentioned is the central,
plane-surface land in the cutting faces 23 and 24,
35 defined therein by the chip grooves 33 and 34. The
plane land, of course, serves to transfer the cutting
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--10--
loads from the insert in either the 3a or 3b position to
the rear pocket surface.
FIG. 9 shows greatly magnified the detail of
the milling cutter l which is encircled and identified
by the reference symbol IX in FIG. 2. This drawing
shows that the cutting edges 30 of the in~ hle
f;n;ch;ng inserts 3a arranged on the face 4 of the
cutter body 2 protrude axially slightly beyond the
secondary cutting edges 3l of the indexable roughing
10 insert 3b arranged on the outer peripheral surface 12 of
the cutter body 2, e.g., by approximately 0.05 mm or
0.002 inches. However, this drawing also shows that the
cutting edges 30 of the indexable inserts 3b arranged on
the outer circumferential surface 12 of the cutter body
2 protrude radially slightly beyond the secondary
cutting edges 31 of the ;n~e~hle insert 3a arranged on
the face 4 of the cutter carrier base 2, e.g., also by
about 0.05 mm or 0.002 inches. It was established that
this relative arrangement of these two groups of
indexable inserts 3a and 3b on the cutter body 2 makes
it possible to attain an optimal function of a milling
cutter l that is utilized as a face milling cutter.
This relationship of the inserts in the 3a and
3b insert positions, respectively, automatically sets
the depth of the f;n; sh; ng cut taken by insert 3a
following after the roughing cut by the axially-oriented
insert 3b. Moreover, in combination with the slight,
radially outward offset of the peripheral insert 3b, the
axial offset of the insert 3a permits it to share the
roughing load along the lower portion of its rounded
corner cutting edge 32 at all feed rates, and along
progressively more of that edge 32 at moderate to heavy
feed rates which increase the chip load per insert at
the same cutting speed. It will be understood that the
feeding direction of the cutter l is radial, with a
slight forward tilt of the cutter rotational axis in the
feeding direction to lift the cutting edges above the
=
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finished surface on the trailing side of the rotating
cu-tter.
The ability to use the same insert configur-
ation for roughing and f;n;~h;ng by the same cutter, and
to use the same individual insert in four orientations
with four cutting edges both as a roughing and a finish-
ing insert, greatly increases the cutting efficiency and
the cost efficiency of the cutting operation, as well as
eliminating the necessity of stocking multiple forms of
10 cutting inserts, as the single insert of the invention
form serves all stations of the cutter.
The features of the invention believed new and
patentable are set forth in the claims.
