Chip control insert

Chip control insert having parallel face central aperture diamond configuration, cutting edges extending above a planar recess, annular and discrete corner island locating surfaces, each with radially outward pointed chip breaking projections extending from the annular locating surface toward the center of each cutting edge and from each of the islands toward its respective acute and obtuse corner. Islands at the acute corners are larger than islands at the obtuse corners.

BACKGROUND OF THE INVENTION 
Many specific forms of chip control cutting inserts are known in the art 
including cemented carbide cutting inserts having parallel faces, 
generally diamond configuration, bottom recesses below the cutting edges 
and chip breaking walls projecting up from the bottom recess. 
Special chip breaking effects have been achieved by providing a series of 
chip deflecting grooves or depressions spaced along the cutting edge such 
as disclosed in U.S. Pat. No. 4,215,957, 4,273,480 and 4,335,984. Recess 
grooves with chip breaking projections, particularly for use in turning 
operations are disclosed in U.S. Pat. No. 3,792,514, wherein a uniform 
concave groove is provided along each cutting edge in combination with a 
nose projection in the concave groove isolated from an island on the 
insert serving for chip breaking and light cutting operations. 
Another form of such insert is disclosed in U.S. Pat. No. 4,214,845 
including a pair of chip breaking projections at each corner with another 
projection on the bisector behind the first projections, as well as 
adjacent the center of each cutting edge. U.S. Pat. No. 3,815,192 
discloses a polygonal throw away insert having a plurality of cutting 
edges on one major surface along the edges of all of the sides thereof and 
a plurality of projection rows provided on said surface along and spaced 
from the cutting edges so as to form chip breakers. Adjacent projections 
along each projection row define chip curling zones therebetween. The most 
relevant prior art known to applicants is illustrated in four perspective 
views of alternative commercial inserts identified in applicants' drawings 
as Prior Art FIGS. 8A-8D, the last of which is taken from U.S. Pat. No. 
4,304,509. 
BRIEF DESCRIPTION OF THE PRESENT INVENTION 
The present cutting insert has been developed for general purpose 
application with effective satisfactory chip breaking, turning, facing, 
boring and contouring operations. The insert employs on each face an 
annular planar seating surface surrounding a central through aperture for 
locating and securing the insert on a holder, with radial chip breaking 
extensions projecting into close proximity with the cutting edge at the 
center of each polygon side. 
The preferred embodiment includes polygon corner chip breaking means having 
ramp walls extending from the bottom surface of the cutting edge periphery 
in the form of separate radially pointed islands, each having surrounding 
concave ramp walls.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
With reference to FIG. 1, insert 10 has a generally diamond exterior 
configuration with respectively 80.degree. and 100.degree. opposite acute 
and obtuse angles. It is provided with cutting edge 1 and 12 extending to 
entry line 14 from which entry surface 16 descends at a 20.degree. angle 
to bottom line 18 extending around planar bottom surface 20. Bidirectional 
acute cutting corners 22, 24 have rounded primary cutting edges and 
bidirectional obtuse cutting corners 26, 28 are used to create chamfers. 
Relatively larger chip breaking islands 30 are provided at the acute 
corners and relatively smaller chip breaking islands 32 at the obtuse 
corners, each of which is flanked by chip breaking concave ramp surfaces 
34 having an incident angle of 32.degree. as shown in FIGS. 2, 3, 5 and 6. 
As also shown in such figures, seating surface 36 of each island extends 
above cutting land 12; likewise, the principal annular seating surface 38 
as illustrated in FIG. 4. 
Conventional locating/clamping aperture 40 having cylindrical side wall 42 
is provided at the center of the insert within annular seating surface 38. 
Pointed extensions 44 adjacent the midpoint of each insert cutting edge 
serve as chip breaking points. Each of extensions 44 and seating surface 
38 are surrounded by incident 32.degree. ramp surfaces 46 which serve to 
curl chips up and break them into short lengths. 
Typical dimensions shown in FIGS. 2-6 of the various fragmentary sectional 
views correspond to a 1/2" IC chip control insert having 1/4" thickness 
with the same locating and chip breaking pattern on both sides for 
reversible use with sides extending normal to the faces and with neutral 
cutting edge land 12. From the dimensions illustrated, it is is apparent 
that cutting land 12 is typically 0.004" below each island and annular 
seating surface 36, 38, with a 20.degree. inclined surface 16 leading to 
groove bottom 20, which is planar and 0.0125" below the island and annular 
locating surfaces providing a generally open path for coolant access. 
In order to accommodate a potential for slight warpage, island surfaces 36 
may be provided with a nominal molded surface slightly higher, e.g., 
0.002", than annular seating surface 38 in order to assure grind clean up 
in a common seating plane.