U.S. patent application number 17/321394 was filed with the patent office on 2021-09-02 for orderly-micro-grooved pcd grinding wheel and method for making same.
The applicant listed for this patent is Changsha University of Science and Technology. Invention is credited to Peihao CAI, Yongle HU, Yifeng JIANG, Yuanqiang LUO, Cong MAO, Aiming TANG, Weidong TANG, Lairong YIN, Mingjun ZHANG, Yujie ZHONG.
Application Number | 20210268626 17/321394 |
Document ID | / |
Family ID | 1000005638334 |
Filed Date | 2021-09-02 |
United States Patent
Application |
20210268626 |
Kind Code |
A1 |
MAO; Cong ; et al. |
September 2, 2021 |
ORDERLY-MICRO-GROOVED PCD GRINDING WHEEL AND METHOD FOR MAKING
SAME
Abstract
An orderly-micro-grooved PCD grinding wheel includes a wheel
hub, a polycrystalline diamond (PCD) film, a number of
micro-grinding units and a number of microgrooves. The PCD film is
deposited on an outer circumferential surface of the wheel hub. The
PCD film is processed by a water-jet guided laser device to form
the microgrooves with high depth-width ratio and micro-grinding
units with positive rake angles on the entire outer circumferential
surface of the PCD film. An axial length of each micro-grinding
unit and an axial length of each microgroove are equal to a
thickness of the grinding wheel, respectively. The microgrooves are
spaced apart by the micro-grinding units.
Inventors: |
MAO; Cong; (Changsha,
CN) ; YIN; Lairong; (Changsha, CN) ; ZHONG;
Yujie; (Changsha, CN) ; HU; Yongle; (Changsha,
CN) ; LUO; Yuanqiang; (Changsha, CN) ; TANG;
Weidong; (Changsha, CN) ; CAI; Peihao;
(Changsha, CN) ; ZHANG; Mingjun; (Changsha,
CN) ; JIANG; Yifeng; (Changsha, CN) ; TANG;
Aiming; (Changsha, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Changsha University of Science and Technology |
Changsha |
|
CN |
|
|
Family ID: |
1000005638334 |
Appl. No.: |
17/321394 |
Filed: |
May 14, 2021 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
16677635 |
Nov 7, 2019 |
|
|
|
17321394 |
|
|
|
|
PCT/CN2019/090698 |
Jun 11, 2019 |
|
|
|
16677635 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B24D 5/02 20130101 |
International
Class: |
B24D 5/02 20060101
B24D005/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 13, 2018 |
CN |
201810608183.3 |
Claims
1. A grinding wheel, comprising: a wheel hub; a polycrystalline
diamond (PCD) film; a plurality of micro-grinding units; and a
plurality of microgrooves; wherein an outer circumferential surface
of the wheel hub is deposited with the PCD film; the plurality of
micro-grinding units and the plurality of microgrooves are orderly
distributed on a whole outer circumferential surface of the PCD
film; the plurality of micro-grinding units form a part of the PCD
film; and the plurality of microgrooves are spaced apart by the
plurality of micro-grinding units; each of the plurality of
microgrooves and each of the plurality of micro-grinding units both
have an axial length equal to a thickness of the grinding wheel;
the micro-grinding units each comprise two side surfaces and an
outer surface; the microgrooves each comprise two side walls that
form one of the two side surfaces of two adjacent micro-grinding
units, respectively; and the micro-grinding units each have a rake
angle that is positive.
2. The grinding wheel of claim 1, wherein the rake angle is
10.degree.-40.degree..
3. The grinding wheel of claim 1, wherein the micro-grinding units
each have a clearance angle of 20.degree.-50.degree..
4. The grinding wheel of claim 1, wherein the micro-grinding units
have substantially the same geometric shapes and dimensions.
5. The grinding wheel of claim 1, wherein a thickness of the PCD
film is 1-2 mm.
6. The grinding wheel of claim 1, wherein each of the
micro-grinding units has a circumferential width of 80-150 .mu.m
and a radial height of 500-800 .mu.m
7. The grinding wheel of claim 1, wherein each of the microgrooves
has a circumferential width of 20-50 .mu.m, a depth of 500-800
.mu.m and a depth-width ratio of 10-40:1.
8. The grinding wheel of claim 1, wherein the wheel hub is made of
titanium alloy.
9. The grinding wheel of claim 8, wherein the wheel hub has a
diameter of 100-200 mm and a thickness of 6-20 mm.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S.
application Ser. No. 16/677,635, filed on Nov. 7, 2019, now
pending, which is a continuation of International Patent
Application PCT/CN2019/090698, filed on Jun. 11, 2019, and claims
the benefit of priority from Chinese Patent Application No.
201810608183.3, filed on Jun. 13, 2018. The content of the
aforementioned application, including any intervening amendments
thereto, is incorporated herein by reference.
TECHNICAL FIELD
[0002] This application relates to a grinding wheel and preparation
thereof, and more specifically to an orderly-micro-grooved PCD
grinding wheel and a method for making the same.
BACKGROUND
[0003] Grinding has been widely applied in the precision machining
due to the characteristics of high processing precision and good
surface quality. However, in the traditional grinding process,
abrasive grains are irregularly arranged on the working surface of
the grinding wheel, and vary in geometrical shape and size, so that
the abrasive grains often cut the surface of the workpiece in a
large negative rake angle during grinding, which will increase the
grinding force ratio, accelerate the conversion of grinding energy
into heat and raise the grinding temperature, affecting the surface
quality and grinding efficiency. In addition, the grinding wheel
also has disadvantages of small chip space and low protrusion of
abrasive grains, and the grains are easy to fall off, which may
easily cause a blockage at the grinding wheel and produce a local
high temperature to burn the workpiece surface, and reduce the
service life of the grinding wheel.
[0004] Extensive researches have been performed to find a method
for improving the grinding efficiency and service life of the
grinding wheel. Chinese Publication No. 107962510A, titled "CVD
diamond grinding wheel with ordered surface micro-structure" put
forward a method in which a diamond film is deposited on the outer
circumferential surface of a grinding wheel hub by chemical vapor
deposition, and a large number of staggered and ordered
microgrooves and grinding units with waist-type top surface are
prepared on the outer circumferential surface of the whole diamond
film by pulsed laser beam. This method improves the removal rate
and grinding efficiency of the surface material and increases the
holding force of the grinding wheel hub for the grinding units,
improving the service life of the grinding wheel to a certain
extent. However, the single grinding unit is still operated at a
zero rake angle during the grinding process, so that the grinding
efficiency and the surface quality cannot be further improved.
Meanwhile, the circumferential spacing of the orderly arranged
grinding units reaches 1 mm, which will result in a typical
intermittent grinding, and the generated periodic vibrations by the
grinding process may also affect the integrity of the ground
surface.
[0005] Further, in order to improve the integrity of the ground
surface and achieve the grinding in a positive rake angle, Chinese
Publication No. 105728961A, titled "Method for manufacturing a new
positive-rake angle diamond grinding tool based on pulse laser",
provides a method for preparing positive rake angles of diamond
abrasive grains by laser. In the method, the large single-layer
diamond abrasive grains orderly arranged on the working surface of
the grinding wheel are ablated by laser to obtain a point angle
less than 90.degree., which enables grinding with a positive rake
angle. The method effectively solves the problem that abrasive
grains of the conventional diamond grinding wheel cut the surface
of the workpiece in a large negative rake angle, which improves the
processing efficiency and reduces the damage to the ground surface,
improving the integrity of the ground surface. However, in the
process of preparing large-sized diamond abrasive grains by laser,
the high laser ablation temperature will inevitably cause partial
graphitization of the diamond abrasive grains, affecting the
positive rake angle cutting of the abrasive grains for the
workpiece surface and reducing the quality of the ground surface.
At the same time, the single large-sized diamond abrasive grain may
fall off if it is subjected to excessive or concentrated force,
which may affect the grinding efficiency and even reduce the
service life of the grinding wheel.
[0006] In order to further improve the quality of the ground
surface and the grinding efficiency, Chinese Patent Application
Publication No. 107243848A, titled "A spiral ordered fiber tool for
positive rake angle processing and preparation method thereof",
discloses a method in which the matrix is prepared on the grinding
wheel hub by pressing and sintering, and the ordered holes are
processed on the matrix using a drilling bit. Then the fiber with
positive rake angle is consolidated in the small holes by the epoxy
resin. The method enables cutting with a positive rake angle, and
further improves the surface quality and the processing precision.
However, since the fiber has a cross-sectional size of 0.8
mm.times.0.8 mm and the number of fibers per square centimeter on
the surface of the tool is only 14.26, the single fiber may have a
large cutting depth, making it difficult to ensure the processing
precision. Moreover, a rupture will occur if a single fiber is
subjected to an excessive or concentrated force, which may affect
the service life of the grinding wheel. There are also great
difficulties in the process that all the fibers are inserted into
the small holes one by one and consolidated.
SUMMARY
[0007] The present disclosure provides a grinding wheel, comprising
a wheel hub, a polycrystalline diamond (PCD) film, a plurality of
micro-grinding units and a plurality of microgrooves;
[0008] wherein an outer circumferential surface of the wheel hub is
deposited with the PCD film; the plurality of micro-grinding units
and the plurality of microgrooves are orderly distributed on a
whole outer circumferential surface of the PCD film; the plurality
of micro-grinding units form a part of the PCD film; and the
plurality of microgrooves are spaced apart by the plurality of
micro-grinding units;
[0009] each of the plurality of microgrooves and each of the
plurality of micro-grinding units both have an axial length equal
to a thickness of the grinding wheel; the micro-grinding units each
comprise two side surfaces and an outer surface; the microgrooves
each comprise two side walls that form one of the two side surfaces
of two adjacent micro-grinding units, respectively; and
[0010] the micro-grinding units each have an positive rake
angle.
[0011] In some embodiments, the positive rake angle of each
micro-grinding unit is 10.degree.-40.degree., and the
micro-grinding units each have a clearance angle of
20.degree.-50.degree..
[0012] In some embodiments, the micro-grinding units have
substantially the same geometric shapes and dimensions.
[0013] In some embodiments, a thickness of the PCD film is 1-2
mm.
[0014] In some embodiments, each micro-grinding unit has a
circumferential width of 80-150 .mu.m and a radial height of
500-800 .mu.m.
[0015] In some embodiments, each microgroove has a circumferential
width of 20-50 .mu.m, a depth of 500-800 .mu.m and a depth-width
ratio of 10-40:1.
[0016] In some embodiments, the wheel hub is made of titanium
alloy; and the wheel hub has a diameter of 100-200 mm and a
thickness of 6-20 mm.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a perspective view and a partial enlarged view
showing a PCD grinding wheel having a number of microgrooves and a
number of micro-grinding units on its entire surface in accordance
with an embodiment of the present invention;
[0018] FIG. 2 is a front view and a partial enlarged view showing
the grinding wheel in contact with a surface of a workpiece in
accordance with an embodiment of the present invention;
[0019] FIG. 3 is a perspective view showing a grinding wheel having
a wheel hub on which a PCD film is deposited in accordance with an
embodiment of the present invention; and
[0020] FIG. 4 is a schematic diagram showing the processing of the
PCD film on the wheel hub of the grinding wheel by a water-jet
guided laser device in accordance with an embodiment of the present
invention.
DETAILED DESCRIPTION OF EMBODIMENTS
[0021] Definitions
[0022] Term "reference plane" is a plane which is perpendicular to
cutting velocity vector at a selected point on a cutting tool.
Herein, the cutting tool may refer to abrasives, or particularly
grinding units.
[0023] Term "cutting plane" is a plane which is tangent to the
selected point of the cutting tool where it is in contact with the
surface of the workpiece. The cutting plane is perpendicular to the
reference plane.
[0024] Term "rake angle" is an angle between a rake face of the
cutting tool and the reference plane. The rake angle may be
categorized into three types: positive, zero or neutral, and
negative. Herein, the cutting tool has a positive rake angle.
[0025] Term "clearance angle" is an angle between a flank face of
the cutting tool and the cutting plane.
[0026] Term "substantially" herein refers to two or more elements
are identical to a great extent or degree, almost, but not
absolutely the same.
[0027] Term "pickling" is a metal surface treatment used to remove
impurities, such as stains, inorganic contaminants, rust or scale
from ferrous metals, copper, precious metals and aluminum alloys,
and a solution called pickle liquor, which usually contains acid,
is used to remove the surface impurities.
[0028] This application will be further illustrated with reference
to the embodiments and drawings.
[0029] Referring to FIG. 1, a grinding wheel includes a wheel hub
1, a polycrystalline diamond (PCD) film 2, a plurality of
micro-grinding units 9 and a plurality of microgrooves 10. An outer
circumferential surface of the wheel hub 1 is deposited with a PCD
film 2. The micro-grinding units 9 and the microgrooves 10 are
orderly distributed on a whole outer circumferential surface of the
PCD film. The microgrooves 10 are configured to hold chip and store
grinding liquid.
[0030] Each microgroove 10 and each micro-grinding unit 9 both have
an axial length equal to a thickness of the grinding wheel. The
microgrooves 10 each have a circumferential width of 20-50 .mu.m, a
depth of 500-800 .mu.m, and a depth-width ratio of 10-40:1. Since
the arrangement of the micro-grinding units 9 and the microgrooves
10 are formed by subtractive manufacturing or processing of the PCD
film, the micro-grinding units 9 are a part of the PCD film. The
microgrooves 10 are spaced apart by the micro-grinding units 9 to
create an ordered arrangement.
[0031] Particularly, referring to a partial enlarged view on the
right side in FIG. 1, the micro-grinding units 9 each comprise two
side surfaces 11, 13 and an outer surface 14. The microgrooves 10
each comprise two side walls 11, 13 which form one of the two side
surfaces 11, 13 of two adjacent micro-grinding units, respectively.
In other words, every two adjacent micro-grinding units and the
microgroove 10 between them share the side walls/surfaces 11,
13.
[0032] Referring to FIG. 2, particularly a partial enlarged view on
the right side, each micro-grinding unit 9 has a rake angle .beta.,
which is the angle between a rake face (i.e. side surface 13) of
the micro-grinding unit 9 and a reference plane .pi..sub.R. The
rake angle .beta. is positive, ranging from 10.degree. to
40.degree.. In an embodiment, the rake angle .beta. is 10.degree.,
15.degree., 20.degree., 25.degree., 30.degree., 35.degree. or
40.degree., for the purpose of illustration.
[0033] Continuing to refer to FIG. 2, each micro-grinding unit 9
has a clearance angle .alpha., which is the angle between a flank
face (i.e. outer surface 14) of the micro-grinding unit 9 and a
cutting plane .pi..sub.C. The cutting plane is tangent to a
selected point of the micro-grinding unit 9 on a surface of a
workpiece 12, as shown in FIG. 2. Here, the selected point refers
to the intersection of the rake face (i.e. side surface 13) and the
flank face (i.e. outer surface 14), as seen from a front view of
the grinding wheel. The reference plane .pi..sub.R is perpendicular
to the cutting plane .pi..sub.C. The clearance angle .alpha. of the
micro-grinding unit 9 is 20.degree.-50.degree.. In an embodiment,
the clearance angle a is 20.degree., 25.degree., 30.degree.,
35.degree., 40.degree., 45.degree. or 50.degree..
[0034] FIGS. 3-4 illustrate main procedures for the manufacturing
of the grinding wheel as shown in FIGS. 1-2.
[0035] Referring to FIG. 3, a layer of a PCD film 2 having a
thickness of 1-2 mm is deposited on a wheel hub 1 by a hot filament
chemical vapor deposition (HFCVD) technique. Hot filament CVD is a
method that has been applied to the deposition of diamond films and
is available to persons skilled in the art. The thickness of the
PCD film 2 may be 2 mm. The wheel hub 1 may be made of titanium
alloy, with a diameter of 100-200 mm and a thickness of 6-12 mm.
Preferably, the diameter of the wheel hub is 100 mm, and the
thickness of the wheel hub is 12 mm. The outer circumferential
surface of the PCD film 2 is polished by ion beam polishing to
reach a surface roughness of 0.15-0.2 preferably 0.2 The outer
circumferential surface of the PCD film 2 is processed by a
water-jet guided laser device, for example Laser MicroJet.RTM.
Integration Package (LMJ-iP) to form a number of microgrooves and
micro-grinding units on the entire surface of the PCD film 2. The
process is a reduction of material, that is subtractive
manufacturing, so the micro-grinding units formed is a part of the
PCD film. In an embodiment, the laser device is an Nd: YAG pulse
laser with a wavelength of 532 nm and a focused spot diameter of
30-100 .mu.m.
[0036] Referring to FIG. 4, the water-jet guided laser device
comprises a laser head 3, a glass window 4, a water chamber 5 and a
nozzle 6. Laser beam 7 emitted by the laser head 3 is focused in
the nozzle 6 through the glass window 4 on the water chamber 5. The
water chamber 5 is pressurized to allow a water jet 8 to be ejected
from the nozzle 6 and to guide the transmission of the laser beam 7
to the outer circumferential surface of the PCD film 2. The
pressure of the water chamber is 2-4 MPa, and the diameter of the
water jet is 20-50 .mu.m. The grinding wheel is offset by a certain
angle that is equal to a desired rake angle (for example
30.degree.) of the micro-grinding unit 9, to form the first single
microgroove 10. The microgroove 10 has an axial length, for example
12 mm, that is equal to the thickness of the grinding wheel. In an
embodiment, the microgroove 10 has a circumferential width of 20
.mu.m, a depth of 500 .mu.m and a depth-width ratio of 25. During
the processing, relative movement between the water jet 8 and the
wheel hub 1 is changed to create the microgroove 10. The grinding
wheel is indexed. When the processing of the first single
microgroove 10 is finished, the outer circumference of the PCD film
2 is rotated over, for example 100 .mu.m, i.e., a circumferential
width of a micro-grinding unit 9, to carry out the processing for
the next microgroove 10. Upon the completion of the second
microgroove 10, the micro-grinding unit 9 is formed between the
first and the second microgrooves 10. Then the micro-grinding unit
9 is processed to form a clearance angle 13, for example
40.degree.. These procedures are repeated to continue to process
the PCD film so as to form a number of microgrooves 10 with high
depth-width ratio and a number of micro-grinding units 9 on the
entire circumferential surface of the PCD film 2. The formed
micro-grinding units 9 have substantially the same shapes and
dimensions. The details about a water-jet guided laser device may
refer to Yaowen W U et al. (Overview on the development and
critical issues of water jet guided laser machining technology,
Optics and Laser Technology, 137 (2021), 106820), Yi S H I et al.
(Texturing of metallic surfaces for superhydrophobicity by water
jet guided laser micro-machining, Applied Surface Science, 500
(2020) 144286) which are incorporated herein by reference.
[0037] The PCD film 2 on the wheel hub 1 is finally processed with
ordered arrangement of the microgrooves 10 and the micro-grinding
units 9, as shown in FIGS. 1 and 2. A pickling treatment and
ultrasonic cleaning in deionized water for 15 min may be further
performed on the grinding wheel.
[0038] The outer circumferential working surface of the grinding
wheel is provided with a large number of micro-grinding units with
positive rake angle, which ensures that the micro-grinding units
are worked in a positive rake angle during grinding, lowering the
grinding force ratio and temperature, effectively reducing the
damage to the surface and greatly improving the grinding
performance and efficiency.
[0039] A large number of microgrooves with high depth-width ratio
are provided on the outer circumferential working surface of the
grinding wheel, which greatly improves the chip-holding space.
Meanwhile the micro-grinding units are orderly arranged so that
ordered chip-removing channels are formed during grinding, which
greatly improves the chip-removing capacity and makes the grinding
wheel less prone to blockage, effectively promoting the entering of
the grinding fluid into the grinding zone, significantly improving
the cooling effect for the grinding zone, reducing the thermal
damage to the workpiece surface and further enhancing the grinding
quality.
[0040] When the micro-grinding units are processed by the water-jet
guided laser technique, the laser beam propagates along the water
jet in a total reflection. During the processing, the laser is
guided by the water jet to the surface of the PCD film to ablate
the PCD film, and the ablated PCD film is carried away by the water
jet. Additionally, the water jet also cools the surface of the PCD
film, which effectively prevents the graphitization of the
micro-grinding units, providing better grinding performance and
greatly enhancing the surface quality.
[0041] The service life of the grinding wheel is extended. The PCD
film on the outer circumferential surface of the grinding wheel is
deposited by the HFCVD technique. The micro-grinding units are a
part of the PCD film, which prevents the micro-grinding units from
singly falling off due to excessive or concentrated grinding force
and significantly improves the service life of the grinding
wheel.
[0042] The number of effective cutting edges per unit area is
increased and alleviates the periodic vibration during grinding.
The micro-grinding units have the characteristics of high
protrusion and good consistency, so that the cutting edge of each
micro-grinding unit can participate in the grinding.
[0043] The shape and dimension of the micro-grinding units on the
outer circumferential surface of the grinding wheel both have a
good periodicity. Therefore, in the preparation process, the
relative motion relationship between the Laser-Micro jet device and
the grinding wheel can be controlled by the numerical control
technology, which greatly reduces the difficulty in the preparation
of the grinding wheel and lowers the cost.
[0044] It should be understood that the above embodiments are only
illustrative of the invention and are not intended to limit the
invention. In addition, various equivalent modifications and
changes made by those skilled in the art without departing from the
spirit of the invention fall within the scope of the invention as
defined by the appended claims
* * * * *