Note: Descriptions are shown in the official language in which they were submitted.
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CIJTTING TOOL AND INSERT TIIE:REFOR
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U/\ ICGROUNI~ Old INV~Nl10i.~1
it field of toe Invc!~tloll:
Iota! i1~velllion relcltes L,cnercllly TV tile Held ox chip Eurlt~ ;, gutting tools
utilizing inclexable cUtlillg bits or inserts More partlc-llarly, tile illvelltion pertains to a
at USE t lo lo lvil~l, at cyllllclrlcEll slick c11~Ci IT~ecllclllically lleltl,
10 Irlllltil~le easily Cllttilll~ inserts on jar spl~ericEll quietly end will Alcott cuttlnL~ easels for
forming a recluses cut
)tsclil)lit~ r toe I to 1
L5clll nosed ellcl mills Err kllowll Which can perEorln ornni-tlirectional
quietly end contourirlg of irregular shapes on work pieces Ogle class of such prior art
fools Iris quietly easels in~e~rcllly [ormecl wltl1 tile cutter clue or celr~entecl carbide
quietly elemellls brazed onto lllC' Klutz' booty. Sclcll cJeslC~lls reclUile consitlerable
man~liacturill~ erupt end their cutting;, easels can be refound or sllarpeneci only Whitehall
Z0 corlsiclerable tli~Iiculty end With tile recluirecl Use of suitable grinclin~ machines Aster
re~rinclillg, a loss of clial11etricai size occurs, necessitation;, careful macllille acijustments
wren tic Ironical Idol is retulllecl to selvict! 'Isles tools with Intel ally Iolrrletl cutting
blushes are ox a sunnily material anti tllelefole are lilniteti to use on certain narrow
cottagers of worl~plece materials Ogle suckle Lyle brazed tool is tiisclosetl In U S
I'atenl No, 11,132,rl93 -Isles, Issued Jan~lEIl y 2, 1979.
Jo sequent class owe clown Bali nicety ITllllS Eta en inclexable Quietly;'
clelllellts or illserts Scull tools fire (llsCIosetl~ or exEllnlJle~ in Us, i~Ec~tent No- 75,~9G
- lclslllllalTli et at Issued Novel11b~l Z7, 1979 allot U-S- I.'atenl No, ll,252~1100 - Ml7,uno of
311 Elm issllecl l~t~bl hall y 2~1, 19c~ 1 . I tie l<iSIIilIEllrli t t Eli I isle t~llCt~ cliscl(7ses a solute With El
Colossal Lotte! old I t~llj,El Jill;, SUI~[EJCC~ wllilt~ toll h~llzlll1o it .11- pal~l1l leaches il1sel to
nloulltetl ill a cyclical stanch pOsitioll With equal il1sert~s Mueller tlimemr;loll Iyln;~
It ISSUE lull tot t! Ells Ct~iVilll, -It'll Elk t~llt~lEc~t~ Solute Ells Mix lo
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P-20 1 I
et at. specifically leaches noll-overlappinp~ of the cutting Jones of each insert employed
in the cut. Milling cutters with inserts moulltecl in stand-up position require more
mounting room thereby loading to lowered rigidity of the cutter body. Additionally,
insole is in Lowe stay us) InoLll)ting alr-1ngell~e1-l ale subjected to Inaximurrl cutting Forces
5 through a minimum dimension of the insert body material. Cutters employing inserts
with non-planar Rowley faces produce narrower, stringy chips of non-uniform width which
ate snore prone to chip cloggilll7 conditions in the cut.
SUMMARY OF Al lNVl~NTlOI~I
I
no improved cutting tool for generating arcuate profiles is disclosed and
US ernbocliecl as a bclll nosed end hill having n cylindrical shawl< terminating in a
spherically shaped quietly end. rho CUttillg end includes at least two cavities shaped for
lay-down mounting receipt of first and second cutting inserts, each insert presenting an
15 acolyte cutting edge with a radius of curvature equal -to the radius of the cut to be
taken. The arcuate cutting edge of the first insert extends radially outwardly from the
longitudinal axis of the Schick. Lowe cutting zone ox the second insert overlaps that ox the
first insert. I ash insert has first and second major faces in the form of equilateral
polygons connected by planar flank surfaces. The first major face includes convex
20 portions intersecting each flank< surface in an acute angle to form identical arcuate
cutting edges along each stale of the polygon. The second major face is planar and
intersects each flank< surface in an obtuse angle. Mounting the fully index able inserts in
the so-called "Jay-down" or "on-edge" configuration results in placing the majordimension of the insert body behind the active cutting edge to enable the insert to better
25 withstand the creating forces imposed on it. Additionally, lay-down insert mounting
results in shallower rno-1nting cavities in the tool body, thereby providing added strength
and rigidity there to .
l5RI~F DESCRIPTION OF THY DRAWING
3û
the objects and features of the invention will becorne-apparent from a
reading ox a detailed description of a preferred embodiment, Tulane in conjunction with
the drawing, in which:
.
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l'-20 ;~.Z2~
Fig. 1 is a perspective view of a ball nosed end mill designed in
accordance with the principles of thy invention;
Fig. 2 is a plan view of the end mill of Fig. 1 taken normal to the
lon~ilu<lin.ll axis of Cue tool shank;
lug. 3 is a plan view of the end mill of Fig. 1 taken parallel to the
longitudinal axis of the tool shawl< from the CUttillg end;
Fix is a sectional view taker along line I of Fig. 2;
Fig. 5 is a top plan view of an index able cutting insert designed in
accor-l.lllce with the pi inciples of toe invelltiol);
Pig. G is a front view of the insert of Pig. S;
Fig. 7 is a side view of the insert of Fig. 5;
lug. PA is a perspective view of the insert of Fig. S; end
lucks. 8 and 9 are respectively top and front views owe an alternative body
of an insert designed in accordance with the principles of the invention.
DWIGHT ED DESCRIPTION
With reference to jigs. I a ball nosed end mill 100 has a substantially
cylindrical shank 101 terminating in a substantially spherical cutting end 110 and a
mounting end (not shown) Welch can be fashioned in any of a number of conventional
shapes for retention by a machine spindle or tool mounting device.
i .
In the spherical cutting end 110 are positioned mounting cavities for
Index able cutting inserts muon ted in so-called "lowdown" or "on-edge" con figuration -i.e.
with a major dimension of the insert Icing rearwardly of the active cutting edge whereby
a major face of the insert acts as a clearance face, while the minor Elan< faces serve as
rake or chip engaging surfaces for their respective cutting edges. In the embodiment
illustrated, the ball nosed end mill 100 has three cavities for mating lay-down receipt of
three inserts 10, 11 and 12. this invention contemplates the use of at least two cutting
inserts. Ike number of inserts depend on the size of the inserts used along with the
desired radius of the arcu.lte ploEile to be maclljnecl in a worlcpiece in a tool of the
invention. Additionally, peripheral inserts (not shown) could be mounted along a portion
of the cylindrical shawl< to extend the depth of cut taken by the disclosed cutting tool.
P-20 ~l2Z't3~
Chip gullet 102 is provided adjacent arcuate cutting edge 12c of insert 12,
while clip gullet 103 lies adjacent arcuate cutting edges 10c and 11c of inserts 10 and
11, respectively. edges 10c, tic and 12c all lie in substantially the same axial plane.
the CUttillg one ox il)sel-t 12 overlaps bottle those of irlsert 10 end insert 11. this is best
5 seen with reference to Fig. 2 where a projection of insert 12 is shown in dashed phantom
lines and is desigtlateci 12p. In this manner, inserts 10, 11 and 12 cut a continuous
arc-lclte profile having a substantially uniforln racli-ls - i.e. a substantially hemispherical
profile with no gaps due to insert spacing.
The radially innermost corner aye of insert 10 intersects or extends just
beyond longitudinal axis lo of the cutter body shank. This provides strength and shear
cultinls action at the norlnally vulllcrclble center cutting portion of the too.
The radially innermost end of cutting edge 12c lies, as seen from Fig.; 2,
at an angle at from axis lo, and angle at is less than angle a, the angle of the radially
outermost end of cutting edge 10c with respect to axis Al Hence, the cutting zone of
insert 23 overlaps tilt of insert 10 by the angle b - i.e. a _ at l b. Ire purpose of this
overlap is twofold. First, it prevents leaving of cusps on toe world surface gel)eratscl, end
second, tool life is enhanced. In the area of overlap (angle by, inserts 10 and 12 are
subjected to only one half the feed rate encountered where no overlap occurs (angle at).
With no overlap, i.e. with angle at equal to angle a, a minute amount of insert corner
wear would cause the cutter body to impact the work surface.
Overlap b is equal to the angle created by lines extending from the center
point 20 of the hemispherical cutting eons 110 over the respective corner radii of insert
10 and of insert 12 projected 180 out of its mounting position as insert 12p. The
magnitude of angle b is dependent pun three factors: insert inscribed circle diameter,
inter t corner r azaleas, end cut t let booty clime ton .
the stale Celsius of inserts 10, 11 and 12, for example surface 10R ox
insert 10 lug. 2), are commonly rerolled to as Elarlks. I-lowever, when the inserts are
mounted in lay-down fashion as shown, flank surface 10R becomes the chip engaging or
Rowley face. the rays faces of the inserts of this involution are Slat planet surfaces. In
I
P-20
operacioll~ chips are generated having substantially uniform thickness and flow freely
across the unlestlictecl planar rake faces end are expelled via chip gullets 102 end 103.
Arcuate Rowley faces, on the other hand, tend to result in thinner, stringy chips more prone
Lo) Lowe
In Fig. 4 it will be apparent that by positioning insert 10 angularly
inwclrclJy towalcls toe tool axis, C-lttillg clearance lo is obtained. The insert's supporting
cavity surface 41 is at a relatively shallow depth, approximately equaling the insert's
Thickness, tl)Cleby le.lVilll!, s~ll)stcll~ial lass in body 110 surrounclill~ the insert mounting
cavities. Tilts results in strong insert support and cutter body stiffness. The difference
between the cutting radius SUE and tool body radius 13R equals cutter body clearance 45.
issue, as seen from Fig. lo, each insert has a countersunk cavity for receipt
of an appropria tell headed muon tying screw member I which threadingly engages a
tapped hole in booty pox lion 110.
A preferred insert is sol forth ill I its. 5, 6, 7 and I Insert 5 presents
three identical arcuate cutting edges 51 and has the form ox an equilateral triangle. It
will be apparent Jo those skilled in the art that this invention is not limited to triangular
inserts. Any equilateral polygonal shape can be utilized.
The equilateral wrangler shape of insert 5 is formed by three planar
flanks Sly, a planar bottom mounting surface SO and a major top cage inducting three
arcuate cylindrical surfaces A, B and C. Surfaces A, 13 and C have common boundaries
at lines 50, 56 end 58. 'I've intersection of surfaces A, 13 and C with a corresponding
adjacent flank surface Al provides three iclenCical arcuate cutting edges 51 each having
gutting radius R (Fits. PA).
Surfaces /\, I, and C have respective axes of generation generally
transverse to their associated cutting edges end exCendlllg at an acute angle 70 to a
plane parallel to the plalle Ox Sirius 55. A preIerrecl range of angle 70 runs from about
5 degrees to about 20 degrees and the value of angle 70 is governed by tile cutter body
diameter. Tile larger the cutter body diameter, the smaller is angle 70.
~.22~22~
P-20
Faces Al are sloped inwardly Erwin cutting edges 51 to bottom face 55
such that each Rowley face Al intersects its associated surface A, En or C in an acute angle
end such that each Rowley face intersects planar surface 55 in an obtuse angle.
PA central hole 53 having countersunk portion 52 is provided for receipt of
a suitable insert mounting screw.
Planar surfaces Al function as the rake faces while cylindrical surfaces A,
I C EUnC'ti'.)l'l as clecllclllce or relict surfaces for their respective cutting edges when
10insc rut 5 is mounted to body portion 110 of the ball nosed end mill 100 of Figs. 1-4.
no alternative insert designed In accordance with the invention is shown
in lugs 8 and 9. Insert 8 has an equilateral triangular shape bounded by three planar
flank surfaces 8G sloping inwardly from major top surface 80 to bottom planar mounting
15 surface 83. In this alternative embodiment, top surface 80 Is spherical an intersects
each flanlc surface 82 to form three identical arcuate cutting edges 81. A central
aperture I with countersunk portion lo is provided for receipt of a suitable mounting
screw. When used with the gutting tool of Figs. lo flat surfaces 86 serve as race faces
for their respective cutting edges, and spherical surface 80 serves as a clearance or
20 relief surface.
It is to lye understood that specific embodiments of this invention have
been described for the sake of example only. Other alternative arrangements within the
scope ox the appended claims will be apparent to those skilled in the art.
