Note: Descriptions are shown in the official language in which they were submitted.
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POSITIVE CUTTING INSERT WITH COMPOUND CLEARANCE FACES
BACKGROUND OF THE INVENTION
1. Field of the Invention.
The present invention relates to a cutting insert with
compound clearance faces for use in milling operations. The
first clearance face proximal to the cutting edge is radiused and
the second clearance face is planar.
The present invention further relates to cutting inserts
which are pressed into final shape.
10 The present invention further relates to a cutting insert
which achieves cutting face geometries and clearance faces which
were formerly available only with ground type cutting tools.
The present invention further relates to a metal cutting
insert having improved cutting edge strength.
15 2. Description of the Related Art.
Kaminski,.U.S. Patent No. 5,071,291 discloses an internal
disk milling cutter with an improved cutting insert. The cutting
insert has a general wedge shape with an upper surface that is
ground or otherwise formed so as to be concave thereby creating a
pair of coplanar cutting edges that sweep back symmetrically from
a forward most cutting corner or point. In particular, the upper
surface of the insert is comprised of a pair of flat, triangular
top faces that slope downward at a shallow angle to the center of
the insert. The pair of cutting edges thereby formed are
generally V-shaped and coplanar.
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There is no showing of the compound clearance faces present
in the instant application. Accordingly, the present application
differs from Kaminski '291.
Satran et al., U.S. Patent No. S,078,550 discloses a cutting
insert for use in rotary milling cutters. The insert has a side
relief flank and a side base edge defined between the side relief
flank and a base surface. The side relief flank comprises a
first and second component side relief flank surface which meet
at an intersection line. The first component side relief flank
extend along the side relief flank from a first position adjacent
a leading end of the insert and located at an intermediate
position thereof to a second position intersecting the cutting
edge and adjacent a trailing end of the insert.
The component flank surfaces are substantially planar and
are angularly disposed with respect to one another so that an
insert side relief angle defined with respect to the cylindrical
holder in the region of the leading end substantially equals an
insert side relief angle in the region of the trailing end.
Satran '550 differs from the present invention because the
component relief flank surfaces of Satran '550 are planar,
whereas the component relief flank surfaces of the present
invention are comprised of a convexly curved first relief flank
surface, as seen in a side sectional view, and a planar
secondary relief flank surface. It has been determined that a
radiused primary clearance adjacent the cutting edge imparts
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improve strength to the cutting edge. Accordingly, the present
nvention differs from Satran '550.
SUMMARY OF THE INVENTION
The present invention is a cutting insert having compound
clearance faces and which is formable without the need for
expensive grinding operations. The insert a polygonal indexable
cutting insert having improved edge strength. The insert is
comprised of a top surface, a planar bottom surface which is
smaller than the top surface, and a side wall extending outwardly
at an obtuse angle from the bottom surface and intersects the
top surface to define the body of the insert. The intersection
of the side wall and the top surface defines a cutting edge. The
side wall is comprised of side flank portions which are defined
as that portion of the side wall which extends from one corner of
the insert to the adjacent corner of the insert. Each side flank
is comprised of a primary clearance surface and a secondary
clearance surface. The primary clearance surface is convexly
radiused, as seen in a side sectional view, and extends from the
cutting edge to a distance on the flank intermediate the top and
bottom surface. The secondary clearance surface is planar and
extends along the flank from the bottom surface to intersect with
the primary clearance surface at the previously described
distance intermediate the top and bottom surface. The
intersection of the secondary clearance surface and the bottom
surface forms the clearance edge of the insert.
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The top surface of the insert may be flat or have a curved
çlearance face, or may be provided with a variety of different
top forms, which include different geometries and chipbreakers as
are within the scope of those of ordinary skill in the art.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a top perspective view of the polygonal insert.
Figure 2 is a top plan view of the polygonal insert.
Figure 3 is an end plan view of the insert showing the
compound clearance surfaces.
Figure 4 is a detailed view of the insert in a tool holder.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Turning now to the drawings wherein like numbers depict like
structures, insert 10 is comprised of a top surface 12, a planar
bottom surface 14, which is smaller than the top surface, and a
sidewall 16 extending outwardly from the bottom surface at an
obtuse angle and intersects the top surface to define a body 18
of the insert. The orientation of the side wall to the top and
bottom surface provides the insert with a positive clearance
orientation.
The intersection of the side wall with the top surface
defines cutting edge 20 which, as can be seen in the Figure 2, is
straight. The intersection with the bottom surface defines
clearance edge 22, which, as can be seen in the drawings, is also
a straight line.
The sidewall is comprised of side flank portions 24. Each
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side flank portion is composed of a primary clearance surface 26,
which is adjacent to the cutting edge, and a secondary clearance
surface 28, which is adjacent the clearance edge. The primary
clearance surface, as seen in a side sectional view, is convexly
curved. The curved primary clearance surface imparts improved
strength to the cutting edge, and further provides for extra
clearance along the flank of the insert. The secondary clearance
surface is planar and intersects the primary clearance surface at
some distance d, along a junction line 30, which is intermediate
the top and bottom surface.
The top surface may be provided with a variety of top forms,
and chipbreakers, depending upon the material to be cut and the
use to which the insert would be put. For example, the insert
could be equipped with a convexly curved top surface 32, or any
other top form desired by the designer.
The insert is designed for use in a peripheral rotary
milling cutter having replaceable inserts.
Those skilled in the art will recognize that many variation
are possible without departing from the scope and spirit of the
invention.
