U.S. patent application number 16/392999 was filed with the patent office on 2020-10-29 for design for internal cooling passages for rotating cutting tools.
This patent application is currently assigned to United Technologies Corporation. The applicant listed for this patent is United Technologies Corporation. Invention is credited to Robert W. Day, Changsheng Guo, Gordon Miller Reed, Zhigang Wang.
Application Number | 20200338649 16/392999 |
Document ID | / |
Family ID | 1000005147404 |
Filed Date | 2020-10-29 |
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United States Patent
Application |
20200338649 |
Kind Code |
A1 |
Wang; Zhigang ; et
al. |
October 29, 2020 |
DESIGN FOR INTERNAL COOLING PASSAGES FOR ROTATING CUTTING TOOLS
Abstract
A cutting tool comprising a tool body comprising a shank and a
cutter opposite the shank, the body defining a length from a shank
end to an end face opposite the shank end, a central axis extends
along the length of the body; at least one tooth having a cutting
edge, the cutting edge extending along the tooth from the shank to
the end face; a flute formed adjacent the at least one tooth; at
least one cooling channel formed in the tooth proximate the at
least one cutting edge, the at least one cooling channel having an
elongated cross sectional shape with an elliptical portion and a
circular portion opposite the elliptical portion, wherein the
elliptical portion is located proximate the cutting edge.
Inventors: |
Wang; Zhigang; (South
Windsor, CT) ; Guo; Changsheng; (South Windsor,
CT) ; Day; Robert W.; (Enfield, CT) ; Reed;
Gordon Miller; (Plantsville, CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
United Technologies Corporation |
Farmington |
CT |
US |
|
|
Assignee: |
United Technologies
Corporation
Farmington
CT
|
Family ID: |
1000005147404 |
Appl. No.: |
16/392999 |
Filed: |
April 24, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B23B 51/02 20130101;
B23B 2251/40 20130101; B23B 51/06 20130101 |
International
Class: |
B23B 51/06 20060101
B23B051/06; B23B 51/02 20060101 B23B051/02 |
Goverment Interests
U.S. GOVERNMENT RIGHTS
[0001] This invention was made with Government support under
contract LIFT007B-1 awarded by the United States Department of
Energy. The government has certain rights in this invention.
Claims
1. A cutting tool comprising: a tool body comprising a shank and a
cutter opposite said shank, said tool body defining a length from a
shank end to an end face opposite said shank end, a central axis
extends along said length of said body; at least one tooth having a
cutting edge, said cutting edge extending along said tooth from
said shank to said end face; a flute formed adjacent said at least
one tooth; and at least one cooling channel formed in said tooth
proximate said at least one cutting edge, said at least one cooling
channel having an elongated cross sectional shape with an
elliptical portion and a circular portion opposite said elliptical
portion, wherein said elliptical portion is located proximate said
cutting edge; wherein said at least one cooling channel comprises a
major axis aligned with a direction of resultant cutting force of
said cutting edge.
2. (canceled)
3. The cutting tool according to claim 1, wherein said elongated
cross sectional shape is configured to rout a liquid coolant toward
said elliptical portion proximate said cutting edge from said
circular portion.
4. The cutting tool according to claim 3, wherein said at least one
cooling channel is configured such that a centrifugal force propels
said liquid coolant into said elliptical portion.
5. The cutting tool according to claim 4, wherein said centrifugal
force is aligned tangential to a flow direction of said liquid
coolant within said at least one cooling channel.
6. The cutting tool according to claim 1, wherein said elongated
cross sectional shape of said at least one cooling channel is
configured to maintain a liquid coolant within a nucleate boiling
region.
7. The cutting tool according to claim 1, wherein said elongated
cross sectional shape of said at least one cooling channel is
configured to force a liquid coolant toward a hottest portion of
said tooth proximate said cutting edge.
8. The cutting tool according to claim 7, wherein said liquid
coolant is selected from the group consisting of water, nitrogen,
carbon dioxide, and ammonia.
9. The cutting tool according to claim 1, wherein said at least one
cooling channel extends through said body from said shank end to
said end face.
10. The cutting tool according to claim 1, wherein said at least
one cooling channel extends to a cooling channel outlet at said end
face.
11. The cutting tool according to claim 10, wherein said at least
one cooling channel is configured as an open system, such that said
coolant exits said cooling channel outlet.
12. The cutting tool according to claim 10, wherein said at least
one cooling channel is configured as a closed system, such that
said coolant is supplied from said shank end proximate to said end
face and returns to said shank end within said tool body.
13. The cutting tool according to claim 12, wherein said tool body
comprises a central return cooling channel configured to carry
coolant from said end face to said shank end.
14. The cutting tool according to claim 1, wherein said elongated
cross sectional shape and location is configured to rout a liquid
coolant toward said elliptical portion proximate said cutting edge
in which said coolant has vaporized.
15. A process for cooling a cutting tool comprising: providing a
tool body comprising a shank with a shank end and a cutter opposite
said shank, said cutter defining an end face; at least one tooth
having a cutting edge, said cutting edge extending along said tooth
from said shank to said end face; at least one cooling channel
formed in said tooth proximate said at least one cutting edge, said
at least one cooling channel having an elongated cross sectional
shape with an elliptical portion and a circular portion opposite
said elliptical portion, wherein said elliptical portion is located
proximate said cutting edge; flowing a liquid coolant through said
at least one cooling channel; and routing said liquid coolant
within said elongated cross sectional shape from said circular
portion toward said elliptical portion proximate said cutting
edge.
16. The process of claim 15, further comprising: propelling said
liquid coolant with a centrifugal force into said elliptical
portion of said at least one cooling channel.
17. The process of claim 16, wherein said centrifugal force is
aligned tangential to a flow direction of said liquid coolant
within said at least one cooling channel.
18. The process of claim 15, further comprising: maintaining said a
liquid coolant within a nucleate boiling region by use of said
elongated cross sectional shape of said at least one cooling
channel.
19. The process of claim 15, further comprising: forcing a liquid
coolant toward a hottest portion of said tooth by employing said
elongated cross sectional shape of said at least one cooling
channel.
20. The process of claim 19, further comprising: routing said
liquid coolant toward said elliptical portion in which said coolant
has vaporized by locating said elongated cross sectional shape
proximate said cutting edge.
Description
BACKGROUND
[0002] The present disclosure is directed to supplying coolant to
cutting tools that comprise internal cooling channels equipped to
transport coolant to the cutting edge for end mills or drill tips
for drills. Particularly, the disclosure presents a cooling channel
that incorporates a cross-section with an elongated shape.
[0003] Machining metals and similar materials, can require cutting
fluids applied to the cutting area to suppress the high cutting
temperature and lubricate tool-chip contact interface.
Traditionally these fluids have been applied by various nozzles. It
becomes more common to supply high pressure fluids through the
tool, which is also referred to coolant through. Certain
coolant-through cutting tools, such as milling cutters, drills and
reamers, utilize circular (cross section) shaped channels to
deliver fluid from the tool shank to the cutting area.
[0004] These state-of-the-art cooling passage designs have a
variety of shortcomings. Current cooling channel design has
ineffective cooling due to the relatively low heat transfer
coefficients associated with cooling outside of the nucleate
boiling region of the coolants utilized. The location and circular
shape cross-section of current cooling channels do not provide
effective cooling to the tool cutting edges where it is most
required. Moreover, multi-axis milling centers require fluid pumps
that consume high energy levels to deliver a large amount of
coolant at high pressure.
[0005] What is needed is an improved cooling channel with a
cross-section that delivers coolant into regions that are the
hottest.
SUMMARY
[0006] In accordance with the present disclosure, there is provided
a cutting tool comprising a tool body comprising a shank and a
cutter opposite the shank, the tool body defining a length from a
shank end to an end face opposite the shank end, a central axis
extends along the length of the body; at least one tooth having a
cutting edge, the cutting edge extending along the tooth from the
shank to the end face; a flute formed adjacent the at least one
tooth; at least one cooling channel formed in the tooth proximate
the at least one cutting edge, the at least one cooling channel
having an elongated cross sectional shape with an elliptical
portion and a circular portion opposite the elliptical portion,
wherein the elliptical portion is located proximate the cutting
edge.
[0007] In another and alternative embodiment, the at least one
cooling channel comprises a major axis aligned with a direction of
resultant cutting force of the at least one cutting edge.
[0008] In another and alternative embodiment, the elongated cross
sectional shape is configured to rout a liquid coolant toward the
elliptical portion proximate the cutting edge from the circular
portion.
[0009] In another and alternative embodiment, the at least one
cooling channel is configured such that a centrifugal force propels
the liquid coolant into the elliptical portion.
[0010] In another and alternative embodiment, the centrifugal force
is aligned tangential to a flow direction of the liquid coolant
within the at least one cooling channel.
[0011] In another and alternative embodiment, the elongated cross
sectional shape of the at least one cooling channel is configured
to maintain a liquid coolant within a nucleate boiling region.
[0012] In another and alternative embodiment, the elongated cross
sectional shape of the at least one cooling channel is configured
to force a liquid coolant toward a hottest portion of the tooth
proximate the cutting edge.
[0013] In another and alternative embodiment, the liquid coolant is
selected from the group consisting of water, nitrogen, carbon
dioxide, and ammonia.
[0014] In another and alternative embodiment, the at least one
cooling channel extends through the body from the shank end to the
end face.
[0015] In another and alternative embodiment, the at least one
cooling channel extends to a cooling channel outlet at the end
face.
[0016] In another and alternative embodiment, the at least one
cooling channel is configured as an open system, such that the
coolant exits the cooling channel outlet.
[0017] In another and alternative embodiment, the at least one
cooling channel is configured as a closed system, such that the
coolant is supplied from the shank end proximate to the end face
and returns to the shank end within the tool body.
[0018] In another and alternative embodiment, the tool body
comprises a central return cooling channel configured to carry
coolant from the end face to the shank end.
[0019] In another and alternative embodiment, the elongated cross
sectional shape and location is configured to rout a liquid coolant
toward the elliptical portion proximate the cutting edge in which
the coolant has vaporized.
[0020] In accordance with the present disclosure, there is provided
a process for cooling a cutting tool comprising providing a tool
body comprising a shank with a shank end and a cutter opposite the
shank, the cutter defining an end face; at least one tooth having a
cutting edge, the cutting edge extending along the tooth from the
shank to the end face; at least one cooling channel formed in the
tooth proximate the at least one cutting edge, the at least one
cooling channel having an elongated cross sectional shape with an
elliptical portion and a circular portion opposite the elliptical
portion, wherein the elliptical portion is located proximate the
cutting edge; flowing a liquid coolant through the at least one
cooling channel; and routing the liquid coolant within the
elongated cross sectional shape from the circular portion toward
the elliptical portion proximate the cutting edge.
[0021] In another and alternative embodiment, process further
comprises propelling the liquid coolant with a centrifugal force
into the elliptical portion of the at least one cooling
channel.
[0022] In another and alternative embodiment, the centrifugal force
is aligned tangential to a flow direction of the liquid coolant
within the at least one cooling channel.
[0023] In another and alternative embodiment, the process further
comprises maintaining the liquid coolant within a nucleate boiling
region by use of the elongated cross sectional shape of the at
least one cooling channel.
[0024] In another and alternative embodiment, the process further
comprises forcing a liquid coolant toward a hottest portion of the
tooth by employing the elongated cross sectional shape of the at
least one cooling channel.
[0025] In another and alternative embodiment, the process further
comprises routing the liquid coolant toward the elliptical portion
in which the coolant has vaporized by locating the elongated cross
sectional shape proximate the cutting edge.
[0026] Other details of the cutting tool are set forth in the
following detailed description and the accompanying drawings
wherein like reference numerals depict like elements.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 is an isometric view of an exemplary cutting
tool.
[0028] FIG. 2 is a side view of the exemplary cutting tool of FIG.
1.
[0029] FIG. 3 is a top view of the exemplary cutting tool of FIG.
1.
[0030] FIG. 4 is a bottom view of the exemplary cutting tool of
FIG. 1.
[0031] FIG. 5 is an isometric view of an exemplary cutting tool
with a closed cooling system.
[0032] FIG. 6 is a side view of the exemplary cutting tool of FIG.
5.
[0033] FIG. 7 is a top view of the exemplary cutting tool of FIG.
5.
[0034] FIG. 8 is a section view A-A of the exemplary cutting tool
of FIG. 5.
[0035] FIG. 9 is a schematic diagram of an exemplary cutting
tool.
[0036] FIG. 10 is a schematic diagram of exemplary cooling channels
within the exemplary cutting tool shown in FIG. 9.
[0037] FIG. 11 is a cross-section of an exemplary cooling
channel.
[0038] FIG. 12 is a cross-section of an exemplary cutting tool with
a cooling channel with an enlarged detailed portion.
DETAILED DESCRIPTION
[0039] Referring to FIGS. 1 through 8, there is illustrated an
exemplary cutting tool 10. A tool body 10 includes a shank 12 and a
cutter 14 opposite the shank 12. The tool body 10 defines a length
L from a shank end 16 to an end face 18 opposite the shank end 16.
A central axis 20 extends along the length of the tool body 10.
[0040] The tool body 10 includes a tooth 22 having a cutting edge
24. The cutting edge 24 extends along the tooth 22 from the shank
12 to the end face 18. There can be multiple sets of the tooth 22,
such as sets of 2, 3 or 4 of the cutting tooth 22. A flute 26 is
associated with the tooth 22 and extends along the tool body 10 up
to the shank 12. The shank 12 is the cylindrical non-fluted portion
of the tool body 10 used to attach and locate the tool body 10 in a
tool holder (not shown). The flutes 26 of the tool body 10 can be
the deep helical grooves running up the cutter 14. The cutting edge
24 (sharp blade) along the edge of the flute 26 defines the tooth
22. The tooth 22 cuts the material, and chips (not shown) of this
material are pulled up the flute 26 by the rotation of the cutter
14. The flutes 26 along with cutting edge 24 of the tooth 22 can
include a helix shape 28 that can have a variety of angles.
[0041] Referring also to FIGS. 9-12, the cutting tool 10 includes
cooling channels 30 formed within cutting tool body 10. The cooling
channels 30 extend along the length of the cutting tool body 10 to
deliver coolant 38. The cooling channels 30 are formed in each
tooth 22 proximate the cutting edge 24. The cooling channel 30 has
an elongated cross sectional shape 31 with an elliptical portion 32
and a circular portion 34 opposite the elliptical portion 32. The
elliptical portion 32 is located proximate the cutting edge 24. The
elongated cross sectional shape 31 retains the necessary mechanical
strength of the cutting edge 24.
[0042] The elongated cross sectional shape 31 and the location of
the cooling channel 30 relative to the cutting edge 24 are
configured to rout a liquid portion of the coolant 38 toward the
elliptical portion 32 proximate the cutting edge 24 in which the
coolant 38 has already vaporized. The vaporized portion of the
coolant 38 is less efficient at removing the thermal energy from
the cutting edge 24 than the liquid coolant 38.
[0043] In an exemplary embodiment, the cooling channel 30 is
configured such that during operation a centrifugal force propels
the liquid coolant 38 into the elliptical portion 32 of the cooling
channel 30, thus providing superior heat removal in that location.
The centrifugal force can be aligned tangential to a flow direction
46 of the liquid coolant 38 within the cooling channel 30. The
elongated cross sectional shape of the cooling channel 30 is
configured to maintain the liquid coolant 38 within a nucleate
boiling region. Maintaining the coolant 38 within the nucleate
boiling region improves the heat transfer from the cutting edge 24.
The elongated cross sectional shape 31 of the cooling channel 30 is
configured to force the liquid coolant 38 toward the hottest
portion of the tooth 22, thus maximizing the removal of thermal
energy being generated at the cutting edge 24.
[0044] The cooling channels 30 shown at FIGS. 1 to 4 are configured
as an open system 36. The channels 30 extend through the tool body
10 from the shank end 16 to the end face 18. Coolant 38 flows out
of a cooling channel outlet 40 at the end face 18.
[0045] As shown in the details at FIGS. 5 to 8, the cooling
channels 30 do not extend to the end face 18. The cooling channels
30 are directed to central return cooling channel 42 configured to
carry coolant 38 from the area near end face 18 to the shank end
16. The configuration of the cooling channels 30 are part of a
closed system 44, such that the coolant 38 is supplied from the
shank end 16 proximate to the end face 18 and returns to the shank
end 16 within the tool body 10.
[0046] The coolant 38 can be selected from the group consisting of
water, nitrogen, carbon dioxide, and ammonia. The coolant 38 can
include liquid nitrogen, and carbon dioxide, peanut oil and the
like. In an exemplary embodiment, the coolant 38 can comprise an
energy efficient refrigerant medium, such as ammonia and carbon
dioxide.
[0047] As seen in FIG. 12, during machining, cutting forces along
the tangential direction F.sub.t and radial direction F.sub.r are
applied on the cutting edge 24. The direction of resultant cutting
force (F.sub.R) 50 on the cutting edge 24 is shown. In an exemplary
embodiment the cooling channel 30 is aligned, such that a major
axis 48 of the elliptical portion 32 aligns with the direction of
the resultant cutting force 50.
[0048] In an exemplary embodiment, the cooling channel 30 can be
located relative to a cutter outer profile 52 at a distance D. The
distance D can be quantified to be about a diameter 54 of the
circular portion 34 or the length of a minor axis 56 of the
elliptical portion 32.
[0049] The area of the elliptical portion 32 can include a ratio
between the major axis 48 and the minor axis 56 from about 4 to
about 8. The shape and size of the elliptical portion 32 is
configured to enlarge a contact area 58 (heat transfer area)
between the coolant 38 and the cutter 14 while utilizing the same
amount of coolant 38. There are structural/mechanical limits to how
large the contact area 58 can be, before the strength of the
cutting edge 24 is reduced to below acceptable limits.
[0050] A technical advantage of the shape and location of the
disclosed cooling channel includes increased heat transfer rates,
and thus greater material removal rates because the high cutting
speeds can be used due to the effective cooling for
difficult-to-machine alloys.
[0051] Another technical advantage of the shape and location of the
disclosed cooling channel includes lower cost and higher
productivity.
[0052] Another technical advantage of the shape and location of the
disclosed cooling channel includes the need for fewer cutting
machines (lower capital investment).
[0053] Another technical advantage of the shape and location of the
disclosed cooling channel results in reduced energy consumption for
coolant delivery and mist collectors.
[0054] Another technical advantage of the shape and location of the
disclosed cooling channel includes an estimated reduction of energy
consumption of up to 50% per manufacturing unit related directly
and indirectly to the lack of having to produce the holistic
modeling on optimal amounts of coolant needed for production.
[0055] Another technical advantage of the shape and location of the
disclosed cooling channel is an estimated reduction of 50% of power
consumption in non-optimized facilities.
[0056] Another technical advantage of the shape and location of the
disclosed cooling channel can result in reduced usage and reduced
waste of coolant, helping to ensure a more environmentally benign
process.
[0057] Another technical advantage of the shape and location of the
disclosed cooling channel can result in improved tool life and
machined surfaces due to the minimization of thermal shock from the
machining process.
[0058] There has been provided a cutting tool. While the cutting
tool has been described in the context of specific embodiments
thereof, other unforeseen alternatives, modifications, and
variations may become apparent to those skilled in the art having
read the foregoing description. Accordingly, it is intended to
embrace those alternatives, modifications, and variations which
fall within the broad scope of the appended claims.
* * * * *