U.S. patent application number 16/547017 was filed with the patent office on 2021-02-25 for rotary cutting tool with enhanced coolant delivery.
This patent application is currently assigned to Kennametal Inc.. The applicant listed for this patent is Kennametal Inc.. Invention is credited to Xiangdong D. Fang, Ruy Frota de Souza Filho, Iranna Shidrameshetra.
Application Number | 20210053128 16/547017 |
Document ID | / |
Family ID | 1000004286132 |
Filed Date | 2021-02-25 |
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United States Patent
Application |
20210053128 |
Kind Code |
A1 |
Filho; Ruy Frota de Souza ;
et al. |
February 25, 2021 |
ROTARY CUTTING TOOL WITH ENHANCED COOLANT DELIVERY
Abstract
A rotary cutting tool includes a main body, a shank portion
having a rearward end, and a flute portion having a forward end
with one or more flanks. One or more connecting fluid holes are in
fluid communication with a central fluid hole and terminates at a
flank at the forward end of the cutting tool. One or more twisted
fluid holes extend through a lobe in the flute portion and
terminates at a flank at the forward end of the cutting tool. A
cross-sectional shape of the connecting fluid holes and the twisted
fluid holes is selected to provide enhanced delivery of fluid to
the cutting edge. In one aspect, the rotary cutting tool is a
modular drill and the flute portion has a pocket for holding a
replaceable cutting insert.
Inventors: |
Filho; Ruy Frota de Souza;
(Latrobe, PA) ; Fang; Xiangdong D.; (Greensburg,
PA) ; Shidrameshetra; Iranna; (Karnataka,
IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kennametal Inc. |
Latrobe |
PA |
US |
|
|
Assignee: |
Kennametal Inc.
Latrobe
PA
|
Family ID: |
1000004286132 |
Appl. No.: |
16/547017 |
Filed: |
August 21, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B23B 51/02 20130101;
B23C 5/28 20130101; B23B 2251/408 20130101; B23B 2250/12 20130101;
B23B 51/06 20130101; Y10T 408/455 20150115 |
International
Class: |
B23B 51/06 20060101
B23B051/06; B23B 51/02 20060101 B23B051/02 |
Claims
1. A rotary cutting tool, comprising: a main body; a shank portion
having a rearward end; a flute portion having a forward end with
one or more flanks, the flute portion having a plurality of flutes
separated by lobes, the flute portion integral and adjacent the
shank portion in an axial direction of the main body; a central
fluid hole extending along a central, rotational axis, RA, from the
rearward end, through the shank portion, partly into the flute
portion, and terminating at a predetermined distance, DT, from the
forward end; one or more connecting fluid holes in fluid
communication with the central fluid hole and terminating at a
flank at the forward end of the flute portion for supplying fluid
to one or more cutting edges of the flute portion; and one or more
twisted fluid holes extending from the rearward end through the
shank portion, through a lobe in the flute portion, and terminating
at a flank at the forward end of the flute portion for supplying
fluid to one or more cutting edges of the flute portion, wherein a
cross-sectional area of the central coolant fluid hole is larger
than a cross-sectional area of one or more of the twisted fluid
holes; wherein the central coolant fluid hole has a non-circular
cross-sectional shape; and wherein each of the twisted fluid holes
has non-circular cross-sectional shape.
2. The rotary cutting tool of claim 1, wherein the one or more
flutes are formed with a helix angle, HA, with respect to a center
rotational axis, RA, of the rotary cutting tool.
3. (canceled)
4. A rotary cutting tool, comprising: a main body; a shank portion
having a rearward end; a flute portion having a forward end with
one or more flanks, the flute portion having a plurality of flutes
separated by lobes, the flute portion integral and adjacent the
shank portion in an axial direction of the main body; a central
fluid hole extending along a central, rotational axis, RA, from the
rearward end, through the shank portion, partly into the flute
portion, and terminating at a predetermined distance, DT, from the
forward end; one or more connecting fluid holes in fluid
communication with the central fluid hole and terminating at a
flank at the forward end of the flute portion for supplying fluid
to one or more cutting edges of the flute portion; and one or more
twisted fluid holes extending from the rearward end through the
shank portion, through a lobe in the flute portion, and terminating
at a flank at the forward end of the flute portion for supplying
fluid to one or more cutting edges of the flute portion, wherein a
cross-sectional area of the central coolant fluid hole is larger
than a cross-sectional area of one or more of the twisted fluid
holes, and wherein one of the one or more connecting fluid holes
and one of the one or more twisted fluid holes emerge in the flank
at the forward end of the flute portion.
5. A rotary cutting tool, comprising: a main body; a shank portion
having a rearward end; a flute portion having a forward end with
one or more flanks, the flute portion having a plurality of flutes
separated by lobes, the flute portion integral and adjacent the
shank portion in an axial direction of the main body; a central
fluid hole extending along a central, rotational axis, RA, from the
rearward end, through the shank portion, partly into the flute
portion, and terminating at a predetermined distance, DT, from the
forward end; one or more connecting fluid holes in fluid
communication with the central fluid hole and terminating at a
flank at the forward end of the flute portion for supplying fluid
to one or more cutting edges of the flute portion; and one or more
twisted fluid holes extending from the rearward end through the
shank portion, through a lobe in the flute portion, and terminating
at a flank at the forward end of the flute portion for supplying
fluid to one or more cutting edges of the flute portion, wherein a
cross-sectional area of the central coolant fluid hole is larger
than a cross-sectional area of one or more of the twisted fluid
holes, and wherein the central fluid hole has a triangular
cross-sectional shape, and wherein the one or more twisted fluid
holes has a different non-circular cross-sectional shape than the
central fluid hole.
6. The rotary cutting tool of claim 1, wherein the central fluid
hole has a triangular cross-sectional shape, and wherein the one or
more twisted fluid holes are "D-shaped" in cross section.
7. The rotary cutting tool of claim 1, wherein the rotary cutting
tool comprises a drill.
8-14. (canceled)
15. The rotary cutting tool of claim 4, wherein the one or more
flutes are formed with a helix angle, HA, with respect to a center
rotational axis, RA, of the rotary cutting tool.
16. The rotary cutting tool of claim 4, wherein the central fluid
hole has a non-circular cross-sectional shape, and wherein the one
or more twisted fluid holes have a non-circular cross-section
shape.
17. The rotary cutting tool of claim 16, wherein the central fluid
hole has a triangular cross-sectional shape, and wherein the one or
more twisted fluid holes are "D-shaped" in cross section.
18. The rotary cutting tool of claim 4, wherein the rotary cutting
tool comprises a drill.
19. The rotary cutting tool of claim 5, wherein the one or more
flutes are formed with a helix angle, HA, with respect to a center
rotational axis, RA, of the rotary cutting tool.
20. The rotary cutting tool of claim 5, wherein the one or more
twisted fluid holes are "D-shaped" in cross section.
21. The rotary cutting tool of claim 5, wherein the rotary cutting
tool comprises a drill.
Description
FIELD OF THE INVENTION
[0001] In general, the invention relates to a rotating cutting
tool, and more particularly, to a rotating cutting tool with a
primary, central fluid hole and a secondary fluid hole for each
flute, each hole having a cross-sectional shape that is selected
for providing enhanced fluid delivery.
BACKGROUND OF THE INVENTION
[0002] Material removal operations can generate heat at the
interface between the cutting insert and the workpiece. Typically,
it is advantageous to provide coolant to the vicinity of the
interface between the cutting insert and the workpiece.
[0003] Even though some prior art arrangements deliver coolant, it
remains highly desirable to provide a rotary cutting tool, such as
a drill, and the like, that delivers fluid in an efficient manner
to the interface between the cutting tool and the workpiece without
significantly altering the performance and properties, such as
torsional stiffness, and the like, of the cutting tool.
[0004] Thus, there is a need to provide improved fluid flow without
significantly altering the performance and properties of the rotary
cutting tool.
SUMMARY OF THE INVENTION
[0005] The problem of improving fluid delivery in a rotary cutting
tool is solved by providing a central fluid hole and one additional
fluid hole for each flute, wherein the central fluid hole has a
larger cross-sectional area than the twisted fluid hole in each
flute.
[0006] The fluid flow rate can be substantially improved when fluid
holes are strategically placed in areas of low stress. The method
of the invention involves defining the central hole size and shape
(round, elongated, tri-lobed) and then adding one or more holes for
each flute that adapted in shape to low stress areas of the drill.
The principles of the invention can be applied to modular or
indexable drills by communicating the central, main fluid hole to
the peripheral ones by means of cross holes or 3D printing.
Additive manufacturing would also allow the principles of the
invention to be applied to carbide drills.
[0007] In one aspect, a rotary cutting tool comprises a main body,
a shank portion having a rearward end, and a flute portion having a
forward end with one or more flanks. The flute portion has a
plurality of flutes separated by lobes. The flute portion is
integral and adjacent the shank portion in an axial direction of
the main body. A central fluid hole extends along a central,
rotational axis, RA, from the rearward end, through the shank
portion, partly into the flute portion, and terminates at a
predetermined distance, DT, from the forward end. One or more
connecting fluid holes are in fluid communication with the central
fluid hole and terminate at a flank at the forward end of the flute
portion for supplying fluid to one or more cutting edges of the
flute portion. One or more twisted fluid holes extend from the
rearward end, through the shank portion, through a lobe in the
flute portion, and terminate at a flank at the forward end of the
flute portion for supplying fluid to one or more cutting edges of
the flute portion. A cross-sectional area of the central coolant
fluid hole is larger than a cross-sectional area of one or more of
the twisted fluid holes. The central coolant fluid hole has a
non-circular cross-sectional shape; and each of the twisted fluid
holes has a non-circular cross-sectional shape.
[0008] In another aspect, a rotary cutting tool comprises a main
body, a shank portion having a rearward end, and a flute portion
having a forward end with one or more flanks. The flute portion has
one or more flutes separated by lobes. The flute portion is
integral and adjacent the shank portion in an axial direction of
the main body. The flute portion including a pocket portion for
holding a cutting insert. A central fluid hole extends along a
central, rotational axis, RA, from the rearward end, through the
shank portion, partly into the flute portion, and terminates at a
predetermined distance, DC, from a base surface of the cutting
insert. One or more connecting fluid holes are in fluid
communication with the central fluid hole and terminate at a flank
of the cutting insert for supplying fluid to one or more cutting
edges of the cutting insert. One or more twisted fluid holes extend
from the rearward end, through the shank portion, through a lobe in
the flute portion, and terminate at a flank of the cutting insert
for supplying fluid to one or more cutting edges of the cutting
insert. A cross-sectional area of the central coolant fluid hole is
larger than a cross-sectional area of one or more of the twisted
fluid holes. The central coolant fluid hole has a non-circular
cross-sectional shape; and each of the twisted fluid holes has a
non-circular cross-sectional shape.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] While various embodiments of the invention are illustrated,
the particular embodiments shown should not be construed to limit
the claims. It is anticipated that various changes and
modifications may be made without departing from the scope of this
invention.
[0010] FIG. 1 is a front view of a rotary cutting tool, such as a
drill with three flutes, according to an embodiment of the
invention;
[0011] FIG. 2 is a top view of the three-flute drill illustrated in
FIG. 1;
[0012] FIG. 3 is a partially enlarged view of a flute portion of
the three-flute drill illustrated in FIG. 1 having a total of six
openings in the three flank surfaces;
[0013] FIG. 4 is a partially enlarged view of another flute portion
of the three-flute drill illustrated in FIG. 1 having a total of
three openings in the three flank surfaces;
[0014] FIG. 5 is a cross-sectional view of a three-flute drill
taken along line X-X of FIG. 1 showing the cross-sectional shape of
Variation A having a central fluid hole with a circular
cross-sectional shape and three twisted fluid holes with a circular
cross-sectional shape according to an embodiment of the
invention;
[0015] FIG. 6 is a cross-sectional view of a three-flute drill
taken along line X-X of FIG. 1 showing the cross-sectional shape of
Variation B having a center fluid hole with a triangular
cross-sectional shape and three twisted fluid holes with an
elongate (i.e., non-circular) cross-sectional shape according to
another embodiment of the invention;
[0016] FIG. 7 is a cross-sectional view of a three-flute drill
taken along line X-X of FIG. 1 showing the cross-sectional shape of
Variation C having a center fluid hole and three twisted fluid
holes, all holes with a circular cross-sectional shape and the
center fluid hole having a larger diameter than the twisted fluid
holes according to another embodiment of the invention;
[0017] FIG. 8 is a cross-sectional view of a three-flute drill
taken along line X-X of FIG. 1 showing the cross-sectional shape of
Variation D having a center fluid hole and three twisted fluid
holes, all holes with a circular cross-sectional shape and the same
diameter according to another embodiment of the invention;
[0018] FIG. 9 is a cross-sectional view of a three-flute drill
taken along line X-X of FIG. 1 showing the cross-sectional shape of
Variation E having a center fluid hole with a triangular
cross-sectional shape and three twisted fluid holes with a
"D-shaped" (i.e., non-circular) cross-sectional shape according to
another embodiment of the invention;
[0019] FIG. 10 is a cross-sectional view of a three-flute drill
taken along line X-X of FIG. 1 showing the cross-sectional shape of
the central fluid hole and the twisted fluid holes of the drill of
the invention;
[0020] FIG. 11 is a cross-sectional view of a three-flute drill
taken along line X-X of FIG. 1 showing the cross-sectional shape of
the central fluid hole and the twisted fluid holes of the drill of
the invention;
[0021] FIG. 12 is a cross-sectional view of a three-flute drill
taken along line X-X of FIG. 1 showing the cross-sectional shape of
the central fluid hole and the twisted fluid holes of the drill of
the invention;
[0022] FIG. 13 is a side view of a rotary cutting tool, such as a
modular drill with two flutes, according to an embodiment of the
invention;
[0023] FIG. 14 is a side view of a cutting insert according to an
embodiment of the invention;
[0024] FIG. 15 is a bottom view of the cutting insert of FIG.
14;
[0025] FIG. 16 is a cross-sectional view of the cutting insert
taken along line 16-16 of FIG. 15.
DETAILED DESCRIPTION OF THE INVENTION
[0026] Referring now to FIGS. 1-4, a rotary cutting tool 10 is
shown according to an embodiment of the invention. In the
illustrated embodiment, the rotary cutting tool 10 comprises a
drill 10 provided with three cutting edges 12 and three flutes 18.
The drill 10 also includes a shank portion 14 having a rearward end
15 and a flute portion 16 having a forward end 13 that are integral
and adjacent to each other in an axial direction of a main body 17.
The forward end 13 of the drill 10 has a cutting tip 24.
[0027] Although the rotary cutting tool 10 comprises a drill in the
illustrated embodiment, it should be appreciated that the
principles of the invention can be applied to any desirable rotary
cutting tool in which fluid is supplied between the cutting
tool/workpiece interface.
[0028] The description herein of specific applications should not
be a limitation on the scope and extent of the use of the cutting
tool.
[0029] Directional phrases used herein, such as, for example, left,
right, front, back, top, bottom and derivatives thereof, relate to
the orientation of the elements shown in the drawings and are not
limiting upon the claims unless expressly recited therein.
Identical parts are provided with the same reference number in all
drawings.
[0030] Approximating language, as used herein throughout the
specification and claims, may be applied to modify any quantitative
representation that could permissibly vary without resulting in a
change in the basic function to which it is related. Accordingly, a
value modified by a term or terms, such as "about",
"approximately", and "substantially", are not to be limited to the
precise value specified. In at least some instances, the
approximating language may correspond to the precision of an
instrument for measuring the value. Here and throughout the
specification and claims, range limitations may be combined and/or
interchanged, such ranges are identified and include all the
sub-ranges contained therein unless context or language indicates
otherwise.
[0031] Throughout the text and the claims, use of the word "about"
in relation to a range of values (e.g., "about 22 to 35 wt %") is
intended to modify both the high and low values recited, and
reflects the penumbra of variation associated with measurement,
significant figures, and interchangeability, all as understood by a
person having ordinary skill in the art to which this invention
pertains.
[0032] For purposes of this specification (other than in the
operating examples), unless otherwise indicated, all numbers
expressing quantities and ranges of ingredients, process
conditions, etc., are to be understood as modified in all instances
by the term "about". Accordingly, unless indicated to the contrary,
the numerical parameters set forth in this specification and
attached claims are approximations that can vary depending upon the
desired results sought to be obtained by the present invention. At
the very least, and not as an attempt to limit the application of
the doctrine of equivalents to the scope of the claims, each
numerical parameter should at least be construed in light of the
number of reported significant digits and by applying ordinary
rounding techniques. Further, as used in this specification and the
appended claims, the singular forms "a", "an" and "the" are
intended to include plural referents, unless expressly and
unequivocally limited to one referent.
[0033] Notwithstanding that the numerical ranges and parameters
setting forth the broad scope of the invention are approximations,
the numerical values set forth in the specific examples are
reported as precisely as possible. Any numerical value, however,
inherently contains certain errors necessarily resulting from the
standard deviation found in their respective testing measurements
including that found in the measuring instrument. Also, it should
be understood that any numerical range recited herein is intended
to include all sub-ranges subsumed therein. For example, a range of
"1 to 10" is intended to include all sub-ranges between and
including the recited minimum value of 1 and the recited maximum
value of 10, i.e., a range having a minimum value equal to or
greater than 1 and a maximum value of equal to or less than 10.
Because the disclosed numerical ranges are continuous, they include
every value between the minimum and maximum values. Unless
expressly indicated otherwise, the various numerical ranges
specified in this application are approximations.
[0034] In the following specification and the claims, a number of
terms are referenced that have the following meanings.
[0035] The singular forms "a", "an", and "the" include plural
references unless the context clearly dictates otherwise.
[0036] "Optional" or "optionally" means that the subsequently
described event or circumstance may or may not occur, and that the
description includes instances where the event occurs and instances
where it does not.
[0037] As used herein, the term "elongate" is defined as something
that is longer than it is wide. In other words, the width is
smaller than its length.
[0038] As used herein, the term "triangular" is defined as an
object having a shape like a triangle, i.e., a polygon having three
sides and three corners.
[0039] As used herein, the term "circular" is defined as an object
having a shape of a circle, i.e., an object having a simple closed
shape. It is the set of points in a plane that are at a given
distance from a given point, the center; equivalently it is the
curve traced out by a point that moves in a plane so that its
distance from a given point is constant. The distance between any
of the points and the center is called the radius.
[0040] As used herein, the term "fluid" is defined as a substance
that has no fixed shape and yields easily to external pressure,
such as a gas or a liquid.
[0041] As used herein, the term "helical" is defined as pertaining
to or having the form of a helix or spiral. A "helix" or "spiral"
is defined as a curve in three-dimensional space formed by a
straight line drawn on a plane when that plane is wrapped around a
cylindrical surface of any kind, especially a right circular
cylinder, as the curve of a screw. A circular helix of radius a and
slope b/a (or pitch 2.pi.b) is described by the following
parametrization:
x(.theta.)=a sin .theta., y(.theta.)=a cos .theta.,
z(.theta.)=b.theta..
[0042] As used herein, the phrase "helix angle" is defined as the
angle between any helix and an axial line on its right, circular
cylinder or cone. The helix angle references the axis of the
cylinder, distinguishing it from the lead angle, which references a
line perpendicular to the axis. Thus, the helix angle is the
geometric complement of the lead angle. The helix angle is measured
in degrees.
[0043] As used herein, the term "3D printing" is any of various
processes in which material is joined or solidified under computer
control to create a three-dimensional object, with material being
added together, such as liquid molecules or powder grains being
fused together, typically layer by layer. In the 1990s, 3D printing
techniques were considered suitable only to the production of
functional or aesthetical prototypes and, back then, a more
comprehensive term for 3D printing was rapid prototyping. Today,
the precision, repeatability and material range have increased to
the point that 3D printing is considered as an industrial
production technology, with the official term of "additive
manufacturing".
[0044] As used herein, the helix of a flute can twist in two
possible directions, which is known as handedness. Most flutes are
oriented so that the cutting tool, when seen from a point of view
on the axis through the center of the helix, moves away from the
viewer when it is turned in a clockwise direction, and moves
towards the viewer when it is turned counterclockwise. This is
known as a right-handed (RH) flute geometry, because it follows the
right-hand grip rule. Flutes oriented in the opposite direction are
known as left-handed (LH).
[0045] As used herein, the term "hole" is defined as an opening
trough something; a gap; a cavity or an aperture that can have any
cross-sectional shape.
[0046] As used herein, the term "triangle" is defined as a polygon
with three sides and three vertices. An "equilateral" triangle is
defined as a triangle in which all three sides are the same
length.
[0047] Referring now to FIGS. 1-3, the drill 10 is made of solid
carbide and manufactured using a 3D printing process. However, it
will be appreciated that the invention can be practiced with a
drill made of any desirable material using any desirable
manufacturing process. For example, the drill 10 can be made of a
substrate of a super hard tool material, such as cemented carbide,
and the like, and manufactured using a sintering process. In
addition, intermetallic compounds, a diamond film, and the like,
can be used as a hard film disposed on the substrate, for enhancing
the cutting durability. For example, some suitable intermetallic
compounds are metals of the groups Mb, IVa, Va, and VIa of the
periodic table of the elements, for example, carbides, nitrides,
and carbonitrides of Al, Ti, V, Cr, etc., or mutual solid solutions
thereof and, specifically, TiAlN alloy, TiCN alloy, TiCrN alloy,
TiN alloy, and the like, can be used. Although a hard film of such
an intermetallic compound can be disposed by a PVD method, such as
an arc ion plating, sputtering, and the like, the hard film may be
disposed by another film formation method, such as a plasma CVD,
and the like. Other suitable materials and manufacturing processes
are encompassed by the principles of the invention.
[0048] The flute portion 16 is provided with a plurality of flutes
18 separated by lobes 20 for discharging chips generated by each of
the cutting edges 12. In other words, the drill 10 is trilobed. The
flutes 18 provided in the flute portion 16 are helical that twist
clockwise around a central, rotational axis, RA, at a predetermined
helix angle, HA, of about 30.degree., and are formed at positions
point-symmetrical with respect to the central, rotation axis, RA.
However, it will be appreciated that the invention is not limited
by the magnitude of the helix angle, HA, and that the invention can
be practiced with any desirable helix angle, HA, in a range between
about greater than 0 degrees and about 75 degrees.
[0049] Although a three-flute drill is shown in the illustrated
embodiment, it should be appreciated that the invention is not
limited by the number of flutes and lobes, and that the principles
of the invention can be practiced in a drill having any desirable
number of flutes, such as two, four, five, six, and the like.
Further, although the three-flute drill 10 in the illustrated
embodiment has a drill diameter, D, of about 16 mm, the drill 10
may have a drill diameter of up to about 56 mm or may have
two-stepped outer diameters (machining diameters).
[0050] One aspect of the invention is that the drill 10 can deliver
an increased amount of fluid flow through the drill 10 to the
interface between the drill 10 and the workpiece (not shown).
Referring now to FIG. 2, the fluid can be supplied through an
internal central fluid hole 26 and one or more twisted fluid holes
27, 28, 29. Each twisted fluid hole 27, 28, 29 has a spiral shape
that can correspond to the path of the flutes 18. In addition, each
twisted fluid hole 27, 28, 29 emerges in an opening (not shown) in
the rearward end 15 of the drill 10 in fluid communication with a
pressurized source of fluid (not shown).
[0051] As shown in FIG. 2, the central fluid hole 26 of the drill
10 extends along the rotational axis, RA, from the rearward end 15
of the drill 10, through the entire shank portion 14, partly into
the flute portion 16, and terminates at some distance, DT, from the
forward end 13 of the drill 10. At the distance, DT, the central
fluid hole 26 branches or splits into one or more connecting fluid
holes 26a, 26b, 26c in fluid communication with the central fluid
hole 26. The central fluid hole 26 and the connecting fluid holes
26a, 26b, 26c can have any desirable cross-sectional shape, such as
circular, non-circular, polygonal, and the like. For example, the
central fluid hole 26 can be concentric with the rotational axis,
RA, and having a circular cross-sectional shape in the shank
portion 14 and a different cross-sectional shape, such as
non-circular, polygonal, and the like, in the flute portion 16 of
the drill 10.
[0052] In one embodiment, there is a one-to-one correspondence
between the total number of connecting fluid holes 26a, 26b, 26c
and the total number of flutes 18. Thus, in the illustrated
embodiment, there are a total of three connecting fluid holes 26a,
26b, 26c; one connecting fluid hole 26a, 26b, 26c in each flute
18.
[0053] In addition, there is a one-to-one correspondence between
the total number of twisted fluid holes 27, 28, 29 and the total
number of flutes 18. Thus, in the illustrated embodiment, there are
a total of three twisted fluid holes 27, 28, 29; one twisted fluid
hole 27, 28, 29 in each flute 18, similar to the connecting fluid
holes 26a, 26b, 26c. It should be noted that, in all embodiments of
the invention, the connecting fluid holes 26a, 26b, 26c and the
twisted fluid holes 27, 28, 29 have a smaller cross-sectional area
than the central fluid hole 26.
[0054] As shown in FIGS. 2 and 3, the forward end 13 of the drill
10 includes three flanks 30, 32 and 34. In this illustrated
embodiment, each of the connecting fluid holes 26a, 26b, 26c and
each of the twisted fluid holes 27, 28, 29 emerges in an opening in
each flank 30, 32, 34. Specifically, the twisted fluid holes 27,
28, 29 emerge into openings 30a, 32a, 34a in the flanks 30, 32, 34,
respectively. Similarly, connecting fluid holes 26a, 26b, 26c
emerge into openings 30b, 32b, 34b in the flanks 30, 32, 34,
respectively.
[0055] Each connecting fluid hole 26a, 26, 26c may extend in a
linear or curved fashion from the central fluid hole 26 to its
respective opening 30b, 32b, 34b. Alternatively, the connecting
fluid holes 26a, 26b, 26c may have a spiral shape that can
correspond to the path of the flutes 18, similar to the twisted
fluid holes 27, 28, 29.
[0056] In the embodiment shown in FIGS. 2 and 3, there are a total
of six openings 30a, 30b, 32a, 32b, 34a, 34b formed in the three
flanks 30, 32, 34 at the forward end 13 of the drill 10. In other
words, each connecting fluid hole 26a, 26b, 26c and each twisted
fluid hole 27, 28, 29 emerge into its own respective opening.
However, it should be appreciated that the invention is not limited
by the number of openings in the flanks and that the invention can
be practiced with a different number of openings in the flanks.
[0057] Referring now to FIG. 4, an alternative embodiment of the
invention is shown in which the three flanks have a total of three
openings 30c, 32c, 34c. Specifically, the connecting fluid hole 26a
merges with the twisted fluid hole 27 to emerge into the opening
30c in the flank 30. Similarly, the connecting fluid hole 26b
merges with the twisted fluid hole 28 to emerge into the opening
32c in the flank 32. Likewise, the connecting fluid hole 26c merges
with the twisted fluid hole 29 to emerge into the opening 34c in
the flank 34.
[0058] CAE Analysis of Fluid Flow Rate
[0059] A CAE analysis of a several variations of a three-flute
drill having a drill diameter, D, of about 16 mm was performed.
Each variation is described in Table I below. FIGS. 5-9 are
cross-sectional views of different variations of the three-flute
drill taken along a plane X-X (FIG. 1) orthogonal to the rotational
axis, RA, for explaining a cross-sectional shape of the central
fluid hole 26 and/or the twisted fluid holes provided in the flute
portion 16 of the drill 10. Variations A-E of the drill 10 of the
invention are shown in FIGS. 5-9, respectively.
TABLE-US-00001 TABLE I Description of Variations Variation FIG. #
Description A 5 One central circular-shaped hole with a diameter of
3.1 mm and one elongated- shaped hole in each flute B 6 One central
triangular-shaped hole and one elongated-shaped hole in each flute
C 7 One central circular-shaped hole with a diameter of 3.1 mm and
one circular-shaped hole in each flute with a diameter of 2.0 mm D
8 One central 2.205 mm diameter hole and one 2.205 mm diameter hole
in each flute E 9 One central triangular-shaped hole and one
semi-circular-shaped hole in each flute
[0060] The results of the CAE analysis are shown in Table II
below.
TABLE-US-00002 TABLE II Results Flow Coolant Body Rate @ area
Volume 20 bar % Variation (mm.sup.2) % A (mm.sup.3) % V (kg/s) Flow
Reference 13.63 100.0% 4715.8 100.0% 0.567 100% A 16.86 123.7%
4554.2 96.6% 0.725 128% B 17.24 126.5% 4534.8 96.2% 0.751 132% C
16.97 124.5% 4548.3 96.4% 0.712 125% D 16.12 118.3% 4591.5 97.4%
0.666 117% E 17.34 127.2% 4531.9 96.1% 0.754 133%
[0061] It should be noted that the reference cutting tool (not
shown) has one circular-shaped hole in each flute with a diameter
of 2.405 mm produced a flow rate of 0.576 kg/s at a pressure of 20
bar and was used as a standard flow rate of 100% for comparing to
the Variations A-E of the invention. As stated above, the central
fluid hole 26 of the drill 10 of the invention in all the
Variations A, B, C and E had a larger cross-sectional area than the
twisted fluid holes 27, 28, 29 in each lobe 20, except for
Variation D in which all the coolant holes (main, central hole and
secondary holes) where circular in cross-sectional shape with the
same diameter of about 2.265 mm.
[0062] As shown in FIG. 5, the three-flute drill 10 of Variation A
has a central fluid hole 26 with a circular cross-sectional shape
and a diameter of about 3.1 mm and three elongated-shaped (i.e.,
non-circular) twisted fluid holes 27, 28, 29. It should be noted
that the central fluid hole 26 is concentric with the rotational
axis, RA. In this example, the drill 10 produced a flow rate of
about 0.725 kg/s, which is an increase of about 128% as compared to
the flow rate of reference cutting tool.
[0063] As shown in FIG. 6, the three-flute drill 10 of Variation B
has a center fluid hole 26 that transitions from a substantially
circular cross-sectional shape to a triangular cross-sectional
shape and three elongated-shaped (i.e., non-circular) twisted fluid
holes 27, 28, 29. The center fluid hole 26 has a larger
cross-sectional area than each of the twisted fluid holes 27, 28,
29. It should be noted that the central fluid hole 26 is concentric
with the rotational axis, RA. In this example, the drill 10
produced a flow rate of about 0.751 kg/s, which is an increase of
about 132% as compared to the flow rate of reference cutting tool,
while reducing the volume of the drill body 17 by about 4%.
[0064] As shown in FIG. 7, the three-flute drill 10 of Variation C
has a center fluid hole 26 with a circular cross-sectional shape
and three twisted fluid holes 27, 28, 29 with a circular
cross-sectional shape. The center fluid hole 26 has a larger
cross-sectional area than each of the twisted fluid holes 27, 28,
29. It should be noted that the central fluid hole 26 is concentric
with the rotational axis, RA. In this example, the drill 10
produced a flow rate of about 0.712 kg/s, which is about a 125%
increase in the flow rate as compared to reference cutting
tool.
[0065] As shown in FIG. 8, the three-flute drill 10 of Variation D
has a center fluid hole 26 with a circular cross-sectional shape
and three twisted fluid holes 27, 28, 29 with a circular
cross-sectional shape. The center fluid hole 26 has a same
cross-sectional area than each of the twisted fluid holes 27, 28,
29. It should be noted that the central fluid hole 26 is concentric
with the rotational axis, RA. In this example, the drill 10
produced a flow rate of about 0.666 kg/s, which is about a 117%
increase in the flow rate as compared to reference cutting
tool.
[0066] As shown in FIG. 9, the three-flute drill 10 of Variation E
has a center fluid hole 26 that transitions from a substantially
circular cross-sectional shape to a triangular cross-sectional
shape and three twisted fluid holes 27, 28, 29 with a non-circular
cross-sectional shape. Specifically, each twisted fluid hole 27,
28, 29 is generally "D-shaped" with a substantially planar wall
portion 27a, 28a, 29a and a curved wall portion 27b, 28b, 29b. In
this embodiment, each planar wall portion 27a, 28a, 29a is radially
inward (i.e. closer to the rotational axis, RA) with respect to
each curved wall portion 27b, 28b, 29b. Similar to other
variations, the center fluid hole 26 has a larger cross-sectional
area than each of the twisted fluid holes 27, 28, 29. It should be
noted that the central fluid hole 26 is concentric with the
rotational axis, RA. In this example, the drill 10 produced a flow
rate of about 0.754 kg/s, which is about a 133% increase in the
flow rate as compared to the reference cutting tool. It should be
noted that the highest flow rate was produced by the three-flute
drill 10 of Variation E.
[0067] In summary, all the Variations A-E of the three-flute drill
10 of the invention produced a significantly increased flow rate as
compared to the reference cutting tool.
[0068] It should be appreciated that the principles of the
invention are not limited to the cross-sectional shape variations
discussed above, and that the invention can be practiced with the
central fluid hole 26 and the twisted fluid holes 27, 28, 29 having
other variations of cross-sectional shapes.
[0069] Referring now to FIG. 10, the three-flute drill 10 of the
invention is identical to the three-flute drill 10 shown in FIG. 9,
except that the twisted fluid holes 27, 28, 29 are rotated 180
degrees with respect to the twisted fluid holes 27, 28, 29 of the
three-flute drill 10 shown in FIG. 9.
[0070] It should be noted that finite element analysis (FEA) has
demonstrated that in overall, the total maximal deformation in the
three-flute drill 10 shown in FIG. 9 is smaller (i.e., the
torsional stiffness is greater) than that in the three-flute drill
10 shown in FIG. 10 in which the substantially planar wall portions
27a, 28a, 29a are radially outward (i.e. farther away from the
rotation axis, RA) than the curved wall portions 27b, 28b, 29b.
[0071] Referring now to FIG. 11, the three-flute drill 10 of the
invention can have a central fluid hole 26 that transitions from a
substantially circular cross-sectional shape to a triangular
cross-sectional shape and three twisted fluid holes 27, 28, 29
having a substantially triangular-shaped cross section.
Specifically, each triangular-shaped twisted fluid hole 27, 28, 29
is defined by three side walls 27c, 28c, 29c and three vertices
27d, 28d, 29d. In this embodiment, one of the side walls 27c, 28c,
29c is radially inward (i.e. closer to the rotational axis, RA)
with respect to each vertex 27d, 28d, 29d. Similar to other
variations, the center fluid hole 26 has a larger cross-sectional
area than each of the twisted fluid holes 27, 28, 29. Similar to
all other variations, the central fluid hole 26 has a larger
cross-sectional area than the twisted fluid holes 27, 28, 29. It
should be noted that the central fluid hole 26 is concentric with
the rotational axis, RA.
[0072] Referring now to FIG. 12, the three-flute drill 10 of the
invention is identical to the three-flute drill 10 shown in FIG.
11, except that the twisted fluid holes 27, 28, 29 are rotated 180
degrees with respect to the twisted fluid holes 27, 28, 29 of the
three-flute drill 10 shown in FIG. 11.
[0073] It should be noted that finite element analysis (FEA) has
demonstrated that in overall, the total maximal deformation in the
three-flute drill 10 shown in FIG. 11 is smaller (i.e., the
torsional stiffness is greater) than that in the three-flute drill
10 shown in FIG. 12 in which the one of the vertices 27d, 28d, 29d
is radially inward (i.e., closer to the rotational axis, RA) than
each of the side walls 27c, 28c, 29c.
[0074] As mentioned above, the shank portion 14 and the flute
portion 16 are integral and adjacent to each other in an axial
direction of a main body 17. However, it should be appreciated that
the principles of the invention can be practiced with a modular
drill.
[0075] Referring now to FIGS. 13-16, a rotary cutting tool 100,
such as a modular drill, for conducting cutting operations on a
workpiece (not shown) when the rotary cutting tool 100 is rotated
about a central, longitudinal axis, RA, is shown according to an
exemplary embodiment of the invention. Like reference numbers for
the drill 10 are increased by 100 for the modular drill 100. Thus,
although not shown in FIG. 13, the modular drill 100 has a central
fluid hole 126 and twisted fluid holes 127, 128 that are identical
to the central fluid hole 26 and twisted fluid holes 27, 28 of the
drill 10. Although depicted as a modular drill in the exemplary
embodiment described herein, it is to be appreciated that the
principles of the invention described herein are applicable to
other rotary cutting tools, such as, for example, without
limitation, a milling tool, a reamer, a tap, an end mill, and the
like.
[0076] The rotary cutting tool 100 is generally cylindrical and
includes a first or forward end 113 and an opposite, second or rear
end 114. The rotary cutting tool 100 has a tool body 117 that
includes a pocket portion 119 proximate the first end 113 for
securely holding a replaceable cutting insert 150, and a flute
portion 116 including a plurality of helical chip flutes 118
separated by lobes 120 extending rearwardly from the first end 113
of the flute portion 116 to the shank portion 114. Similar to the
twisted fluid holes 27, 28, 29 in the lobes 20 of the three-flute
drill 10, the flute portion 116 has twisted fluid holes 127, 128
(FIG. 16) in the lobes 120. The tool body 117 also includes a shank
portion 114 proximate the second end 115 for mounting the rotary
cutting tool 100 in a chuck mechanism of a machine tool (not
shown).
[0077] In the illustrated embodiment, the rotary cutting tool 100
includes two flutes 118 and two lobes 120. However, it should be
appreciated that the invention is not limited by the number of
flutes 118 and lobes 120, and that the invention can be practiced
with a rotary cutting tool having any desirable number of flutes
118 and lobes 120, such as three, four, five, six, seven, eight,
and the like.
[0078] Each chip flute 118 allows chips formed by the cutting edges
112 of the rotary cutting tool 100 to exit from the flute portion
116 during a cutting operation. Each chip flute 118 has a helical
geometry or pattern and are disposed at a helix angle, HA, relative
to the rotational axis, RA. In one embodiment, for example, the
helix angle, HA, is at or about 30 degrees (+/-2 degrees). However,
it will be appreciated that the invention is not limited by the
magnitude of the helix angle, HA, and that the invention can be
practiced with any desirable helix angle, HA, in a range between
about greater than 0 degrees and about 75 degrees.
[0079] Referring now to FIGS. 14-16, the replaceable cutting insert
150 has a front cutting part 152 and a coupling pin 154 extending
axially away from the front cutting part 152 (thus, in an axially
rearward direction). The front cutting part 152 of the cutting
insert 150 defines a cutting diameter, DC. On its circumference,
the cutting insert 150 has an outer peripheral surface 156 that is
interrupted by opposite-facing flutes 158 that start in the cutting
insert 150 and continuously merge into the helical flutes 118
disposed in the flute portion 116 of the main body 117.
[0080] In the exemplary embodiment, the flutes 158 are
substantially helical in shape. The coupling pin 154 of the cutting
insert 150 extends in the axial rearward direction with respect to
the front cutting part 152. The coupling pin 154 is offset in a
radially inward direction from the outer peripheral surface 156.
The replaceable cutting insert 150 also includes a base surface 160
with a central fluid hole 126 in fluid communication with the
central fluid hole 26 (not shown in FIG. 13) in the flute portion
116 of the main body 117 for providing fluid to the cutting edges
112 of the cutting insert 150. In the illustrated embodiment, the
fluid opening 126 may have an identical or different
cross-sectional shape as the central fluid hole 126 in the flute
portion 116 of the main body 117 to provide increased flow rate to
the cutting edges, as compared to conventional cutting inserts with
a circular cross-sectional shape.
[0081] The central fluid hole 126 of the drill 100 extends along
the rotational axis, RA, from the rearward end 115 of the drill
100, through the entire shank portion 114, and through the entire
flute portion 116 and into the pocket portion 119 a predetermined
distance, DB. As shown in FIG. 16, the central fluid hole 126
branches or splits at the predetermined distance, DB, from the base
surface 160 into one or more connecting fluid holes 126a, 126b.
[0082] In one embodiment, the total number of connecting fluid
holes 126a, 126b corresponds to the total number of flutes 118.
Thus, in the illustrated embodiment, there are a total of two
connecting fluid holes 126a, 126b. The connecting fluid holes 126a,
126b can have any desirable cross-sectional shape, such as
circular, non-circular, polygonal, and the like.
[0083] Referring now to FIG. 16, the fluid can also be supplied
through the one or more twisted fluid holes 127, 128. In one
embodiment, the total number of twisted fluid holes 127, 128
corresponds to the total number of flutes 118. Thus, in the
illustrated embodiment, there are a total of two twisted fluid
holes 127, 128. Each twisted fluid hole 127, 128 has a spiral shape
that can correspond to the path of the flutes 118. In addition,
each twisted fluid hole 127, 128 emerges in an opening (not shown)
in the rearward end 115 of the drill 100 in fluid communication
with a pressurized source of fluid (not shown).
[0084] As shown in FIG. 16, the cutting insert 150 includes two
flanks 130 and 132. In the illustrated embodiment of FIG. 8, each
of the connecting fluid holes 126a, 126b and each of the twisted
fluid holes 127, 128 emerges in an opening in each flank 130, 132.
Specifically, the twisted fluid holes 127, 128 emerge into openings
130a, 132b in the flanks 130, 132, respectively. Similarly,
connecting fluid holes 126a, 126b emerge into openings 130b, 132b
in the flanks 130, 132, respectively.
[0085] Each connecting fluid hole 126a, 126b may extend in a linear
fashion from the central fluid hole 126 of the cutting insert 150
to its respective opening 130b, 132b. Alternatively, the connecting
fluid holes 126a, 126b may have a spiral shape that can correspond
to the path of the flutes 118, similar to the twisted fluid holes
127, 128.
[0086] In the embodiment shown in FIGS. 14-16, there are a total of
four openings 130a, 130b, 132a, 132b formed in the flanks 130, 132
of the cutting insert 150. In other words, each connecting fluid
hole 126a, 126b and each twisted fluid hole 127, 128 emerge into a
respective opening. However, it should be appreciated that the
invention is not limited by the number of openings in the flanks
and that the invention can be practiced with a different number of
openings in the flanks. Similar to the embodiment shown in FIG. 3,
for example, the connecting fluid hole 126a may merge with the
twisted fluid hole 127 and emerge in a single opening in the flank
130 of the cutting insert 150. Likewise, the connecting fluid hole
126b may merge with the twisted fluid hole 128 and emerge in a
single opening in the flank 132 of the cutting insert 150.
[0087] In each of the drills 10, 100 of the invention, the total
length of the central fluid hole 26, 126 is larger in
cross-sectional area than each of the connecting fluid holes 26a,
26b, 26c, 126a, 126b and the twisted fluid holes 27, 28, 29, 127,
128 and is equal to at least 60% of the total length of each flute
18, 118 of the drill 10, 100. In addition, the length of the
central fluid hole 26, 126 and the length of the connecting fluid
holes 26a, 26b, 26c, 126a, 126b is in a range between about 60% and
90% of the total length of each flute 18, 118.
[0088] As described above, a drill 10, 100 of the invention
delivers fluid in an efficient manner to the interface between the
cutting tool and the workpiece without significantly altering the
performance and properties, such as torsional stiffness, and the
like, of the drill 10, 100, as compared to conventional drills.
[0089] The patents and publications referred to herein are hereby
incorporated by reference.
[0090] Having described presently preferred embodiments the
invention may be otherwise embodied within the scope of the
appended claims.
* * * * *