U.S. patent application number 15/722728 was filed with the patent office on 2019-04-04 for tool carrier with notch, cutting insert and method for making same.
This patent application is currently assigned to Kennametal Inc.. The applicant listed for this patent is Kennametal Inc.. Invention is credited to Shi Chen, Igor Kaufmann, Neal Myers, Qi Wang.
Application Number | 20190099811 15/722728 |
Document ID | / |
Family ID | 65727768 |
Filed Date | 2019-04-04 |
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United States Patent
Application |
20190099811 |
Kind Code |
A1 |
Wang; Qi ; et al. |
April 4, 2019 |
TOOL CARRIER WITH NOTCH, CUTTING INSERT AND METHOD FOR MAKING
SAME
Abstract
A cutting insert includes a tool carrier having a body with a
pocket, and a cutting tip affixed to the pocket by brazing. The
pocket is defined by a vertical back wall and a horizontal support
surface. A notch is formed at the intersection between the vertical
back wall and the horizontal support surface. The notch has a
non-planar first portion proximate the vertical back wall and
formed with a radius, R1, and a planar second portion extending
between the first portion and the horizontal support surface and
formed at an inclination angle with respect to a plane parallel to
the horizontal support surface of the pocket. The design of the
notch significantly reduces thermal stress and eliminates the
formation of cracks in the pocket of the tool carrier when using an
injection molding process to form the tool carrier.
Inventors: |
Wang; Qi; (Greensburg,
PA) ; Myers; Neal; (Greensburg, PA) ; Chen;
Shi; (N. Huntingdon, PA) ; Kaufmann; Igor;
(Nuernberg, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kennametal Inc. |
Latrobe |
PA |
US |
|
|
Assignee: |
Kennametal Inc.
Latrobe
PA
|
Family ID: |
65727768 |
Appl. No.: |
15/722728 |
Filed: |
October 2, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B23B 2205/12 20130101;
B23B 2226/315 20130101; B23B 2200/0495 20130101; B23B 27/18
20130101; B23B 2226/125 20130101; B23B 27/145 20130101; B23B
2240/08 20130101; B23B 2200/0447 20130101 |
International
Class: |
B23B 27/18 20060101
B23B027/18 |
Claims
1. A tool carrier for a cutting insert, the tool carrier
comprising: a body; a pocket formed in the body for accommodating a
cutting tip of a cutting insert, the pocket defined by a vertical
back wall and a horizontal support surface; and a notch formed at
an intersection between the vertical back wall and the horizontal
support surface of the pocket, wherein the notch has a non-planar
first portion proximate the vertical back wall and formed with a
radius, R1, and a planar second portion extending between the first
portion and the horizontal support surface and formed at an
inclination angle, A, with respect to a plane parallel to the
horizontal support surface of the pocket.
2. The tool carrier according to claim 1, wherein the planar
section portion has a length that is in a range between 0.20 and
0.90 times a total length of the notch.
3. The tool carrier according to claim 1, wherein the planar second
portion of the notch has a length that is 0.75 times a total length
of the notch.
4. The tool carrier according to claim 1, wherein the radius, R1,
is in a range between 0.02 mm and 0.30 mm.
5. The tool carrier according to claim 1, wherein the inclination
angle, A, is in a range between 5 degrees and 60 degrees.
6. The tool carrier according to claim 1, wherein the notch has a
total length of 0.20 mm.
7. The tool carrier according to claim 1, further comprising a
cutting tip affixed to the pocket by brazing.
8. The tool carrier according to claim 7, wherein the cutting tip
is affixed to the pocket by brazing.
9. A cutting insert, comprising: a cutting tip; and a tool carrier
comprising: a body; a pocket formed in the body for accommodating
the cutting tip, the pocket defined by a vertical back wall and a
horizontal support surface; and a notch formed at an intersection
between the vertical back wall and the horizontal support surface
of the pocket, wherein the notch has a non-planar first portion
proximate the vertical back wall and formed with a radius, R1, and
a planar second portion extending between the first portion and the
horizontal support surface and formed at an inclination angle, A,
with respect to a plane parallel to the horizontal support surface
of the pocket.
10. The cutting insert according to claim 9, wherein the planar
section portion has a length that is in a range between 0.20 and
0.90 times a total length of the notch.
11. The cutting insert according to claim 9, wherein the planar
second portion of the notch has a length that is 0.75 times a total
length of the notch.
12. The cutting insert according to claim 9, wherein the radius,
R1, is in a range between 0.02 mm and 0.30 mm.
13. The cutting insert according to claim 9, wherein the
inclination angle, A, is in a range between 5 degrees and 60
degrees.
14. The cutting insert according to claim 9, wherein the notch has
a total length of 0.20 mm.
15. The cutting insert according to claim 9, further comprising a
cutting tip affixed to the pocket by brazing.
16. A method for manufacturing a tool carrier for a cutting insert
by using an injection molding process, the tool carrier comprising
a body and a pocket formed in the body for accommodating a cutting
tip of a cutting insert, the method comprising affixing the cutting
tip to the pocket of a tool carrier by brazing, wherein the pocket
includes a vertical back wall, a horizontal support surface, and a
notch formed at an intersection between the vertical back wall and
the horizontal support surface of the pocket for accommodating
brazing material, and wherein the notch has a non-planar first
portion proximate the vertical back wall and formed with a radius,
R1, and a planar second portion extending between the first portion
and the horizontal support surface and formed at an inclination
angle with respect to a plane parallel to the horizontal support
surface of the pocket, and wherein the notch eliminates formation
of cracks in the tool carrier during the injection molding
process.
17. The method of claim 16, wherein the radius, R1, is in a range
between 0.02 mm and 0.30 mm.
18. The method of claim 16, wherein the inclination angle, A, is in
a range between 5 degrees and 60 degrees.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to cutting inserts and, more
particularly, to cutting inserts comprising a cutting tip made of a
super-hard material, such as PCBN, and the like, affixed onto a
tool carrier made of a suitable material, such as cemented carbide,
and the like.
BACKGROUND OF THE INVENTION
[0002] A super-hard cutting edge is provided to a cutting insert by
affixing a hard-metal body, such as a PCBN tip, to what is commonly
known as a tool carrier or carrier by means of a brazing material,
such as a liquid brazing solder.
[0003] Polycrystalline diamond (PCD) or polycrystalline cubic boron
nitride (PCBN), diamond and diamond composite materials are
commonly used to provide the super-hard cutting edge for cutting
tools, such as cutting inserts used in metal machining.
[0004] Referring now to FIGS. 8 and 9, a conventional tool carrier
100 (also known as a blank) includes a pocket 102 defined by a
vertical back wall 102a and a horizontal seating surface 102b, and
a brazing notch 104 at the intersection between back wall 102a and
the seating surface 102b. The brazing notch 102 is formed with a
radius, R, for accommodating brazing material when affixing a
cutting tip (not shown) to the tool carrier 100. Typically, the
brazing notch 102 has a radius, R, of at least 0.10 mm (0.004
in).
[0005] A problem has been observed when the tool carrier 100 is
manufactured using an injection molding process. The tool carrier
100 may be made of a cemented carbide material. During the
injection molding process, the hot carbide material of the tool
carrier 100 shrinks in the mold when contacting the mold surfaces.
Because shrinkage is proportional to the dimensions of the tool
carrier 100, as shown by the arrows in FIG. 8, the hot carbide
material shrinks more in the horizontal direction, which causes
stress concentration near the brazing notch 104. In addition, a
crack in the tool carrier 100 may occur, due to friction force
between the mold (or die) and the tool carrier 100 when hot
material is injected into the mold (not shown). As the temperature
decreases in the tool carrier 100, the tool carrier 100 begins to
shrink. Because the tool carrier 100 shrinks differently in the
horizontal and vertical direction, the mold will "drag" the notch
portion of the tool carrier 100, thus creating cracks, which is
detrimental to the performance of the tool carrier 100.
[0006] Another problem has been observed when the cutting tip is
affixed to the tool carrier. Typically, a chamfer is formed at the
corners of the cutting tip that are adjacent the pocket walls in an
attempt to provide sufficient bonding force between the cutting tip
and the tool carrier, and to avoid interference between the cutting
tip and the tool carrier. Unfortunately, producing the chamfer in
the cutting tip increases the manufacturing cost of the cutting
insert.
[0007] The present invention has been developed in view of the
foregoing.
SUMMARY OF THE INVENTION
[0008] The problem of the formation of cracks in a tool carrier
during the manufacturing process is solved by providing a notch at
the intersection between the vertical back wall and the horizontal
support surface of the pocket of the carrier formed with a
non-planar first portion having a radius and a planar second
portion having an inclination angle with respect to the horizontal
support surface. The planar second portion allows the mold to move
relative to the tool carrier during shrinkage of the tool carrier
to reduce stress in the vicinity of the notch, thereby eliminating
the formation of cracks in the tool carrier. In addition, the notch
eliminates the need to produce a chamfer in the cutting tip,
thereby decreasing manufacturing cost of the cutting insert.
[0009] In one aspect of the invention, a tool carrier for a cutting
insert, the tool carrier comprises a body; a pocket formed in the
body for accommodating a cutting tip of a cutting insert, the
pocket defined by a vertical back wall and a horizontal support
surface; and a notch formed at an intersection between the vertical
back wall and the horizontal support surface of the pocket, wherein
the notch has a non-planar first portion proximate the vertical
back wall and formed with a radius, R1, and a planar second portion
extending between the first portion and the horizontal support
surface and formed at an inclination angle, A, with respect to a
plane parallel to the horizontal support surface of the pocket.
[0010] In another aspect of the invention, a cutting insert
comprises a cutting tip and a tool carrier. The tool carrier
comprises a body; a pocket formed in the body for accommodating a
cutting tip of a cutting insert, the pocket defined by a vertical
back wall and a horizontal support surface; and a notch formed at
an intersection between the vertical back wall and the horizontal
support surface of the pocket, wherein the notch has a non-planar
first portion proximate the vertical back wall and formed with a
radius, R1, and a planar second portion extending between the first
portion and the horizontal support surface and formed at an
inclination angle, A, with respect to a plane parallel to the
horizontal support surface of the pocket.
[0011] In yet another aspect of the invention, a method for
manufacturing a tool carrier for a cutting insert by using an
injection molding process, the tool carrier comprising a body and a
pocket formed in the body for accommodating a cutting tip of a
cutting insert, the method comprising affixing the cutting tip to
the pocket of a tool carrier by brazing, wherein the pocket
includes a vertical back wall, a horizontal support surface, and a
notch formed at an intersection between the vertical back wall and
the horizontal support surface of the pocket for accommodating
brazing material, and wherein the notch has a non-planar first
portion proximate the vertical back wall and formed with a radius,
R1, and a planar second portion extending between the first portion
and the horizontal support surface and formed at an inclination
angle, A, with respect to a plane parallel to the horizontal
support surface of the pocket, and wherein the notch eliminates
formation of cracks in the tool carrier during the injection
molding process.
[0012] These and other aspects of the present invention will be
more fully understood following a review of this specification and
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] While various embodiments of the invention are illustrated,
the 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.
[0014] FIG. 1 is an isometric view of a cutting insert in
accordance with an aspect of the invention;
[0015] FIG. 2 is an enlarged view of the tool carrier, carrier
pocket and cutting tip of the cutting insert of FIG. 1;
[0016] FIG. 3 is a top view of the cutting insert of FIG. 1;
[0017] FIG. 4 is a cross-sectional view of the cutting insert taken
along line 4-4 of FIG. 3;
[0018] FIG. 5 is an enlarged view of the tool carrier, carrier
pocket and cutting tip of the cutting insert shown in FIG. 4;
[0019] FIG. 6 is an enlarged view of the tool carrier, carrier
pocket and cutting tip of the cutting insert shown in FIG. 5;
[0020] FIG. 7 is an enlarged cross-sectional view of the notch
formed in the carrier pocket in accordance with an aspect of the
invention;
[0021] FIG. 8 is an isometric view of a conventional tool carrier;
and
[0022] FIG. 9 is a cross-sectional view of a conventional notch
formed in the pocket of the conventional tool carrier shown in FIG.
8.
DETAILED DESCRIPTION OF THE INVENTION
[0023] Referring now to FIGS. 1-6, a cutting insert 10 is shown
according to an embodiment of the invention. In general, the
cutting insert 10 includes a tool carrier 12 having a body 13 with
at least one pocket 14. The cutting insert 10 also includes at
least one cutting tip 16 affixed to the tool carrier 12. In the
illustrated embodiment, the tool carrier 12 has a total of four
pockets 14 and four cutting tips 16 affixed thereto. However, it
will be appreciated that the invention is not limited by the number
of pockets and cutting tips, and that the invention can be
practiced with any desirable number of pockets and cutting
tips.
[0024] As used herein, the term "super-hard material" is taken to
mean materials with Vickers hardness greater than about 25 GPa.
Such materials include, but is not limited to, diamond, cubic boron
nitride, boron sub-oxide, boron carbide, polycrystalline diamond
(PCD), polycrystalline cubic boron nitride (PCBN), and silicon
carbide-bonded diamond (ScD).
[0025] As used herein, the term "PCBN" is taken to mean
polycrystalline cubic boron nitride, which typically comprises
grains of cubic boron nitride dispersed within a binder phase
comprising metallic and/or ceramic phases.
[0026] As used herein, the term "cutting insert" refers to pieces
of tungsten carbide or alternative cutting material mechanically
held, brazed, soldered, or welded into position on dies, or
substrate carriers, and discarded when worn out, others being
fitted in their place.
[0027] As used herein, the term "tool carrier" refers to a rigid
body that holds a cutting tip or tips firmly in place so that they
can be utilized in a turning, milling, boring, cutting, or drilling
application.
[0028] The tool carrier 12, also known as a blank, carrier, and the
like, has an aperture 18 for receiving a fastener (not shown) when
mounting the cutting insert 10 to a cutting tool (not shown). Each
pocket 14 is defined by a vertical back wall 14a and a horizontal
support surface 14b that is substantially perpendicular to the
vertical back wall 14a. The pockets 14 are substantially identical
to each other, so only one pocket will be described herein for
brevity.
[0029] The cutting tip 16 is typically made of a super-hard
material. Such materials include, but is not limited to, diamond,
cubic boron nitride, boron sub-oxide, boron carbide,
polycrystalline diamond (PCD), polycrystalline cubic boron nitride
(PCBN), and silicon carbide-bonded diamond (ScD). As shown in FIG.
2, each cutting tip 16 has a top wall 16a, a bottom wall 16b, a
rear wall 16c, a plurality of side walls 16d and a corner radius
16e connecting a pair of side walls 16d. Each cutting tip 16 is
mounted in a respective pocket 14 such that the bottom wall 16b and
the rear wall 16c of the cutting tip 16 contact the vertical back
wall 14a and the horizontal support surface 14b of the pocket 14,
respectively.
[0030] Each cutting tip 16 is affixed to a respective pocket 14 by
any suitable means known in the art. In one embodiment, the cutting
tip 16 is affixed to the pocket 14 by brazing a layer of braze
alloy material 20. After brazing the cutting tip 16 to the tool
carrier 12, the cutting insert 10 may go through standard finishing
processes, such as top and bottom grinding, periphery grinding, and
desired edge preparation and/or coating.
[0031] One aspect of the invention is that the tool carrier 12
includes a notch 22 formed at the intersection between the vertical
back wall 14a and the horizontal support surface 14b of the pocket
14. The notch 22 has a non-planar first portion 22a proximate the
vertical back wall 14a and formed with a radius, R1, in a range
between 0.02 mm and 0.08 mm, and a planar second portion 22b
extending between the first portion 22a and the horizontal support
surface 14b and formed at an inclination angle, A, with respect to
a plane 24 parallel to the horizontal support surface 14b of the
pocket 14. It will be appreciated that the magnitude of the radius,
R1, and the inclination angle, A, depends upon the dimensions of
the tool carrier 12 and cutting insert 16, and therefore the
invention is not limited by the magnitude of the radius, R1, and
the inclination angle, A. The design for the notch 22 is such that
the mold (not shown) will slide on the planar second portion 22b
during shrinkage, thereby substantially reducing stress in the
notch 22 and eliminating cracking of the tool carrier 12 during the
injection molding process.
[0032] In one embodiment, the radius, R1, of the non-planar first
portion 22a is in the range between about 0.02 mm and about 0.08
mm. For example, the radius, R1, can be about 0.04 mm. The
inclination angle, A, of the planar second portion 22b is in the
range between about 10 degrees and about 45 degrees. For example,
the inclination angle, A, can be about 15 degrees. The length, L,
of the planar second portion 22b is in a range between 0.50 and
0.85 times a total length, L.sub.T, of the notch 22. For example,
the length, L, of the planar second portion 22b can be in about
0.15 mm and the total length, L.sub.T, of the notch can be about
0.20 mm.
[0033] Finite element analysis (FEA) of the design of the notch 22
of the invention shows that the maximum stress in the vicinity of
the notch 22 that occurs during shrinkage during the injection
molding process decreased by over a factor of 10, as compared to
the conventional notch design shown in FIG. 9.
[0034] The patents and publications referred to herein are hereby
incorporated by reference.
[0035] Having described presently preferred embodiments the
invention may be otherwise embodied within the scope of the
appended claims.
* * * * *