Note: Descriptions are shown in the official language in which they were submitted.
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CUTTING INSERT WITH CHIP CONTROL
Background of the Invention
Field of the Invention
The invention relates generally to cutting tools for machining chip
forming materials. More particularly, the invention concerns cutting inserts
incorporating chip control geometry particularly advantageous over a mid-range
of feed rates running between very low or finishing feed rates and relatively
high feed rates.
Description of the Prior Art
U.S. Patent No. 4,465,412 to Weekly, issued August 14, 1984,
teaches chip control geometry for a cutting insert particularly useful for
finish cuts at relatively low feed rates. Canadian Patent Application Serial
No. 437,862, filed September 28, 1983, discloses chip control geometry
particularly useful at relatively high feed rates. While both these prior art
concepts have been successful for their intended operating condition, I have
discovered an improved chip control arrangement suitable for use over a
relatively wide mid-range of feed rates, enabling use of cutting inserts of
this invention in many applications previously requiring a switch from one
design to another as one progresses over the encountered range of feed rates
for such applications.
Examples of prior art disclosing multiple chip control grooves
superficially resembling portions of the instant disclosure are:
U.S. Patent 3,213,716 - Gets
U.S. Patent 3,381,349 - Newcomer
U.S. Patent 3,395,434 - Wirfelt
U.S. Patent 3,399,442 - Jones et at.
U.S. Patent 3,733,664 - McKelvey
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U.S. Patent 3,968,550- Jury
lJ.S. Pa ,0~;6,~7~- S~iclel
U.S. Patent 4~288,179 - Kruger et at.
U.S. Patent ~,367,990 Port et at.
SUMMARY OF TAO INVENllON
Tile invelltiorl is emboclis~cl in a preferred form as a LuJly index able
polygonal cutting insert for machining chip forming materials, the insert
incorporating on both chip engaging surfaces thereof improved chip control
including a first cylindrical chip control grove of uniforln width intersecting and
I in parallel to an ark cutting edge at each side of tile polygon. A second
chip control groove adjoins each first control groove and has a cross-section ofJargon radius but of less depth if aft the first clip control groove relative to the
plane of the face of the insert. The second control groove has its largest widthsubstantially mid-way between adjacent cutting corners of the polygon and
gradually decreases to zero width near each corner in the area of the bisector ox
each cutting corner angle. Each arcuate cutting edge along the sides of the
polygon has its lowest point relative to its associated insert chip engagillg face
substantially at the midpoint between adjacent cutting corners. Thus, each
cutting edge presents a positive front to bed< Rowley angle, but can be mounted in a
negative rake tool holder. Toe resultant island area let t in the chip enraging face
Inwardly of the second control groove provides adequate mounting support for
inserts incorporating chip control grooves in both major polygonal faces i.e.
double-sided, fully index able inserts.
IFFY DI~SCI?IPTION OF THY DRAWING
The objects and features of the invention will become apparent
from a reading of a detailed description of a preferred embodiment, taken in
conjunction with the drawing, in which:
Fig. 1 depicts a top plan view of an insert designed in accordance
with the principles of the invention;
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Fig. 2 is a side plan view of the insert of Fig. 1;
. 3 is a cross suckle tow token from line 111-lll of lug. 1; end
Fig. 4 is cross sectional view taken from line IV-IV of Fig. 1.
DETAILLV DISCRETION
With reference to Figs. 1-4, triangular index able cutting insert 100
b.15 Ipl~er Lydia Vowel- SllbSt;lilti.llly parallel loupe Cng;l~in~ or rake [aces, upper face
106 being bounded by arcuate cutting edges AYE extending between cutting
corners A and B, 108~ extending between cutting corners B and C, and 108C
e~tenclillg Litton quietly, corners C and A. As seen in Fig. 2, each arcuate
cumin Dow, such as AYE, has its lowest point relative to its associated chip
engaging face substantially midway between its associated cutting corners A and
13- In thy vicirIity of corners A and En, edge AYE extends for a relatively short
distance 114 substantially parallel to but slightly lower than the plane of top chip
I cnga~illg face 106 end tell smoothly blends into a relatively large circular arc
having radius lo The side form of cutting edges AYE, B, C, as shown in Fig. 2
for edge AYE, creates a positive front to back rake angle. Side or flank faces
113 of insert 100 are substantially perpendicular to the top and bottom chip
engaging faces. Hence, in preferred form, insert 100 is a so-called "positive-
negative" insert - i.e. having cutting edges with positive front to bed< Rowley on a
negative style insert body mountable in a negative Rowley style tool holder pocket.
Intersecting each arcuate edge and extending parallel thereto are
first cylindrical chip control grooves Lola, lob and Luke, each having uniform
width 120. Grooves Lola and lO9PJ smoothly merge at corner 13, grooves lob and
Luke smoothly merge at corner C, and grooves Luke and Lola smoothly merge at
corner A.
adjacent each first groove IOTA, B, C are second cylindrical
3Q control grooves Lola, B, C. Second groove Lola intersects groove Lola along
substantially straight line boundary OWE with its innermost boundary being
arcuate such that groove 11 lo has its widest point 11~ substantially midway
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between cutting corners A and B. Similarly, cylindrical groove 11113 intersects
grove 10~l~ along subs till so igloo e bounclaly Ill end his Jo widest
point substantially midway between CUttillg corners B and C, while cylindrical
groove 11 lo in tersects groove 1 09C along sub Stan tidally straight line boundary
110C end has its wakeless pullout substantially midway between cutting corners C and
A.
Unlike control grooves 109/\, 13, C, control grooves IIIA, 13, C do
not merge into one another, but retooler each vanish to zero width in the area of
the bisector of the angle defined by each cutting corner A, B, C.
Ilk inrlerlIlost Arctic boundaries of control grooves Lola, 13, end
C define an island having surface lû6 tying substantially in the plane of the top
chip engaging surface ox the insert. Island surface 106 has progressively
narrowing projections AYE terminating at point AYE located substantially on the
bisector owe the angle formed by corner A, 106L~ terminating at point 1121~ located
substantially on the bisector ox the angle formed by corner B, and 106C
terminating at point 112C located substantially on the bisector of the angle
formed by corner C. It is to be understood that, in a preferred form, -the chip
control structure being herein described it prided on both major chip engaging
faces of insert 100. With island 106 and associated projections AYE, B and C, anadequate mounting support surface is provided at each major face, thereby
furnishing a double sided fully index able triangular insert with six index ablecutting edges. In general, polygonal inserts of the invent lion will leave on
index able cutting edges, where n is the number of sides of the polygonal shape
used.
Centrally located on the center of the insert loots inscribed circle TO ''
is a cylindrical thlough-hole 102 with countersunk< portions Lola and 10413 for
receipt of a suitably shaped insert mounting screw of a tool holder. ernatively,
insert 100 could be of solid form for use in top clamp style tool holders.
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As seen from Fig. 3, each second groove such as groove lllB has a
larger closs-secliollal I is R2 thin the cross-sectional radius RI sue its
neighboring first groove. The depth below surface 106, Ho of groove lllB is lessthan the depth Hi for groove 109B. The axes of the cylindrical surfaces 109B and5 lllB are respectively Shelley at Of end C2 end are seen to lie inside of cutting
edge 108B and run substantially parallel to a vertical plane containing the cutting
edgy.
Axis C2 lies closer to the center point of the insert's inscribed
circle than axis I as seen from Fig. 4, C2 is located at distance Do from the
10 plane of cutting edge AYE while Of is located a distance Do therefrom. It will
also be apparellt that Do is greater than lo
With the chip control structure above described, prototype inserts
have been successfully operated in metal cutting applications over a feed rate
range from about .005 inches/revolution to about .030 inches/revolution. At the
Joker portion of this feed rate range, the firs-t or outer control groove operates as
a chip directing surface, while its associated inner or second control groove serves
principally as a relief clearance area thereby enabling relatively smooth
uninhibited chip flow with decreased frictional resistance. Toward the higher end
of the useful feed rate range, the second or inner control groove also functions as
a chip directing surface.
One example of a specific prototype triangular insert successfully
tested has an scribed circle with nominal diameter IT of 0.5 inches, an insert
thickness between top and bottom island surfaces of 0.187 inches and a cutting
edge radius Arc of 2.0 inches. leach cutting corner A, B, C is founded off with a
nominal radius of 0.031 inches. The nominal uniform width 120 of each first or
outer control groove is 0.042 inches, while each inner or second groove has a
maximum width 115 at its mid point of 0.073 inches. I. typical value for
dimension 114 of Fig. 2 at each cutting corker is û.100 inches, while typical values
of 0.031 inches for dimension Hi (lug. 3), 0.025 inches for Ho (Fig. 3), 0.06 inches
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for Al (Figs. 3 and 4), 0.155 inches for R2 (Figs. 3 and 4), 0.015 inches for Do (Fig.
I net 0.03 inches or Do (l it ) whelk successfully used.
It should be no ted the t the invent lion described herein has been
5 illustrated with reference to a particular embodiment. It is to be understood that
many details used to facilitate description of such a particular embodiment havebell closely Hot convcl~ience only allele without lhnitalior~ off tube scope ox the
invent lion, which is intended to be measured by the scope and spirit of the
appended claims.
