U.S. patent application number 15/103778 was filed with the patent office on 2016-10-20 for polishing cushion, polishing apparatus, polishing method, and article including object polished by the polishing method.
The applicant listed for this patent is 3M INNOVATIVE PROPERTIES COMPANY. Invention is credited to Michihiro Yamahara.
Application Number | 20160303708 15/103778 |
Document ID | / |
Family ID | 53403680 |
Filed Date | 2016-10-20 |
United States Patent
Application |
20160303708 |
Kind Code |
A1 |
Yamahara; Michihiro |
October 20, 2016 |
POLISHING CUSHION, POLISHING APPARATUS, POLISHING METHOD, AND
ARTICLE INCLUDING OBJECT POLISHED BY THE POLISHING METHOD
Abstract
A polishing cushion for realizing a plurality of types of
polishing with a single polishing apparatus. A polishing cushion
according to one embodiment includes a first outer layer facing one
out of a polishing member and a support member, a second outer
layer facing the other out of the polishing member and the support
member, an inner layer positioned between the first outer layer and
the second outer layer; and a plurality of spaces formed in the
second outer layer which the inner layer is able to enter. The
hardness of the inner layer is lower than both of the hardness of
the first outer layer and the hardness of the second outer
layer.
Inventors: |
Yamahara; Michihiro;
(Kanagawa, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
3M INNOVATIVE PROPERTIES COMPANY |
|
|
|
|
|
Family ID: |
53403680 |
Appl. No.: |
15/103778 |
Filed: |
December 18, 2014 |
PCT Filed: |
December 18, 2014 |
PCT NO: |
PCT/US14/71095 |
371 Date: |
June 10, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B24D 9/08 20130101; B24D
3/002 20130101; B24D 9/02 20130101; B24B 37/22 20130101; B24D 11/02
20130101; B24D 11/003 20130101 |
International
Class: |
B24D 3/00 20060101
B24D003/00; B24D 9/08 20060101 B24D009/08; B24D 11/02 20060101
B24D011/02; B24D 9/02 20060101 B24D009/02 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 20, 2013 |
JP |
2013-263590 |
Claims
1. A polishing cushion comprising: a first outer layer facing one
of a polishing member and a support member, a second outer layer
facing the other out of the polishing member and the support
member; an inner layer positioned between the first outer layer and
the second outer layer; and a plurality of spaces formed in the
second outer layer which the inner layer is able to enter, wherein
a hardness of the inner layer is lower than both of the hardness of
both the first outer layer and the hardness of the second outer
layer.
2. The polishing cushion according to claim 1, wherein the second
outer layer is adjacent the support member.
3. The polishing cushion according to claim 2, wherein the second
outer layer includes a surface containing openings and the surface
is bonded with the inner layer.
4. The polishing cushion according to claim 3, wherein the
plurality of spaces are through-holes.
5. A polishing apparatus comprising: the polishing cushion
according to claim 4; the polishing member; and the support
member.
6. A polishing method using a polishing apparatus, the method
comprising: polishing an object using the polishing apparatus where
a polishing cushion is arranged between a polishing member and a
support member, wherein the polishing cushion includes a first
outer layer facing one of a polishing member and a support member,
a second outer layer facing the other of the polishing member and
the support member, an inner layer positioned between the first
outer layer and the second outer layer; and wherein the second
outer layer includes a plurality of spaces which the inner layer is
able to enter, and wherein a hardness of the inner layer is lower
than both of the hardness of the first outer layer and the hardness
of the second outer layer.
7. An article comprising: the object which is polished using the
polishing method according to claim 6.
Description
BACKGROUND
[0001] The present disclosure relates to a polishing cushion, a
polishing apparatus, a polishing method, and an article including
an object polished by the polishing method.
[0002] Polishing apparatuses for polishing metal materials or the
like are conventionally known. For example, polishing apparatuses
provided with a polishing disk or a polishing wheel are in common
use. UK Unexamined Patent Application Publication No. 813963
describes a contact element for supporting a polishing belt and
applying the polishing belt onto a work piece. This contact element
has a series of ridged sections with a serrated shape and a
material which is softer than the ridged sections is packed into
grooves separating the individual ridged sections. U.S. Pat. No.
7,824,248 describes a driving apparatus for an orbital sander
which, by eccentrically moving a drive shaft, which is eccentric
with respect to a rotating shaft extending from a driving source
provided in a driving section and of which one end is rotatably
coupled with the rotating shaft, around the shaft core of the
rotating shaft in proportion to the rotation of the rotating shaft,
causes a base plate, which is supported on the driving section via
a support pillar formed of an elastic member and fixed to the other
end of the drive shaft, to make an orbital motion.
SUMMARY
[0003] It is useful to be able to perform various types of
polishing with a single polishing apparatus (in other words, for
example, with one polishing disk or endless polishing belt). For
example, it is useful to be also able to intensively polish a
workpiece surface by pressing a polishing surface onto an object
with a relatively high pressure and, at the same time, to finely
finish the workpiece surface by pressing the polishing surface onto
the object with a relatively low pressure. In order to realize a
broad range of types of polishing with one single polishing
apparatus, disposing a cushioning material on a rear side of the
polishing surface may be considered. However, it is difficult to
obtain a desired polishing effect simply by adopting the
conventionally available cushioning materials. Therefore, there is
a demand to realize a plurality of types of polishing with a single
polishing apparatus as described above.
[0004] A polishing cushion according to one aspect of the present
invention includes: a first outer layer facing one out of a
polishing member and a support member; a second outer layer facing
the other out of the polishing member and the support member; an
inner layer positioned between the first outer layer and the second
outer layer; and a plurality of spaces formed in the second outer
layer which the inner layer is able to enter, wherein a hardness of
the inner layer is lower than both of the hardness of the first
outer layer and the hardness of the second outer layer.
[0005] In this aspect, when pressure is applied to the polishing
member during polishing, a part of the soft inner layer enters the
spaces due to the pressure. In a case where the polishing member is
applied to the object at a pressure of a degree at which the spaces
are not entirely packed with the inner layer (that is, at a
relatively low pressure), it is possible to finely finish the
surface by lightly applying the polishing member to the workpiece
surface since the inner layer acts as a buffer for the pressure. On
the other hand, in a case where the polishing member is applied to
the object at a pressure of a degree at which the individual spaces
are packed with the inner layer (that is, at a relatively strong
pressure), the workpiece surface is intensively polished by
transferring almost all of the pressure to the polishing member
since the inner layer is almost completely crushed and
substantially does not act as a buffer for the pressure. In this
manner, it is possible to realize a plurality of types of polishing
with a single polishing apparatus by providing spaces into which
the soft inner layer enters in the outer layer.
[0006] According to one aspect of the present invention, it is
possible to realize a plurality of types of polishing with a single
polishing apparatus.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a perspective diagram of a polishing cushion
according to an embodiment.
[0008] FIG. 2 is an exploded perspective diagram which shows an
example of the polishing cushion according to the embodiment.
[0009] FIG. 3 is an exploded perspective diagram which shows
another example of the polishing cushion according to the
embodiment.
[0010] FIG. 4 is a perspective diagram which shows still another
example of spaces in the polishing cushion.
[0011] FIG. 5 is a perspective diagram which shows yet another
example of spaces in the polishing cushion.
[0012] FIG. 6 is a perspective diagram which shows yet another
example of spaces in the polishing cushion.
[0013] FIG. 7 is a perspective diagram which shows yet another
example of spaces in the polishing cushion.
[0014] FIG. 8 is a perspective diagram which shows yet another
example of spaces in the polishing cushion.
[0015] FIG. 9 is a perspective diagram which shows yet another
example of spaces in the polishing cushion.
[0016] FIG. 10 is a perspective diagram which shows yet another
example of spaces in the polishing cushion.
[0017] FIG. 11 is a diagram of a portable grinder provided with the
polishing cushion according to the embodiment.
[0018] FIG. 12 is an exploded perspective diagram which shows
attachment of the polishing cushion in the portable grinder.
[0019] FIG. 13 is a perspective diagram of a polishing wheel
provided with the polishing cushion according to the
embodiment.
[0020] FIG. 14 is exploded perspective diagram which shows
attachment of the polishing cushion in the polishing wheel.
[0021] FIG. 15 is a diagram of a single action sander provided with
the polishing cushion according to the embodiment.
[0022] FIG. 16 is a diagram of a double action sander provided with
the polishing cushion according to the embodiment.
[0023] FIG. 17 is an exploded perspective diagram which shows
attachment of the polishing cushion in the single action sander or
the double action sander.
[0024] FIG. 18 is a cross sectional diagram which schematically
shows states where the polishing cushion according to the
embodiment is changed by being pressed.
[0025] FIG. 19 is a table which shows the results of polishing
amounts and surface finishing in a working example and a
comparative example.
DETAILED DESCRIPTION
[0026] Embodiments of the present invention will now be described
in detail with reference to the attached drawings. In the
description of the drawings, identical or equivalent elements are
labeled with the same symbols and not repeatedly described.
[0027] First, a structure of a polishing cushion 10 according to an
embodiment will be described using FIGS. 1 to 10. The polishing
cushion 10 is an article disposed between a polishing member and a
support member which are constituent components of the polishing
apparatus. In general, the number of purposes of the polishing is
not limited to one and examples of purposes include various types
of polishing such as greatly shaving away a surface of an object (a
workpiece surface) and finely finishing the surface. The polishing
cushion 10 is used for realizing a plurality of types of polishing
with a single polishing apparatus.
[0028] Note herein that the term "polishing" in the present
specification is a concept which also includes grinding.
Furthermore, the term "polishing member" in the present
specification is a component which has a polishing surface which
contacts a surface of the object. In addition, the term "support
member" in the present specification is a component which directly
or indirectly supports the polishing member and the polishing
cushion 10 during polishing.
[0029] The polishing cushion 10 as shown in FIG. 1 includes at
least three layers. Specifically, the polishing cushion 10 includes
a first outer layer 11 facing one out of the polishing member and
the support member, a second outer layer 12 facing the other out of
the polishing member and the support member, and an inner layer 13
positioned between these two outer layers. The first outer layer
11, the second outer layer 12, and the inner layer 13 are all flat
and these three layers are stacked using an adhesive. The thickness
of each of the layers may be determined in consideration of the
dimensions of the polishing member, the type and dimensions of the
polishing apparatus, and the like.
[0030] The first outer layer 11 and the second outer layer 12 are
manufactured, for example, with natural rubber or synthetic rubber
(for example, urethane rubber or chloroprene rubber) as a main raw
material. On the other hand, the inner layer 13 is, for example, a
foam body obtained from natural rubber or synthetic rubber. A
closed cell foam is more preferable than an open cell foam as the
foam body in consideration of the buffering property and the
elasticity of the inner layer 13. However, an open cell foam type
of foam body may of course be used. Alternatively, the main raw
material of the inner layer 13 may be natural rubber or synthetic
rubber with a lower hardness than those of the first outer layer
and the second outer layer 12.
[0031] The hardness of the inner layer 13 is lower than those of
both of the hardness of the first outer layer 11 and the hardness
of the second outer layer 12. The hardness of each layer is
measured in accordance with "Determination of Hardness of
Vulcanized Rubber and Thermoplastic Rubber (JIS K 6253 (2012
Edition))" which is a standard for measuring the hardness of
rubber. For example, when the inner layer 13 is a material which is
so soft that the hardness is difficult to measure with a Type A
durometer, the hardness of the inner layer 13 may be measured using
a Type E durometer hardness tester. As long as the relationship
described above is satisfied, the hardness of the inner layer 13
and the hardnesses of the two outer layers are not limited to any
specific numerical values. As an example, the hardnesses of the
first outer layer 11 and the second outer layer 12 may be 70
according to the Type A durometer and the hardness of the inner
layer 13 may be five according to the Type E durometer.
Alternatively, the hardnesses of the first outer layer 11 and the
second outer layer 12 may be 50 according to the Type A durometer
and the hardness of the inner layer 13 may be ten according to the
Type E durometer. Note that the first outer layer 11 and the second
outer layer 12 may differ in hardness.
[0032] A plurality of spaces 14 is formed in one (the second outer
layer 12 in the present specification) of the two outer layers. The
spaces 14 may be holes (spaces with no bottoms) 14a penetrating
from one surface of the second outer layer 12 through the opposite
surface as shown in FIG. 2. Alternatively, the spaces 14 may be
recesses (bottomed spaces) 14b formed in one surface of the second
outer layer 12 as shown in FIG. 3. In all cases, the surface which
has the opening sections of the spaces 14 out of the surfaces of
the second outer layer 12 is bonded with the inner layer 13.
[0033] In FIGS. 2 and 3, the circular spaces 14 are arranged in a
staggered manner; however, the shapes and arrangement of the spaces
14 are not limited thereto. Some modified examples of the spaces
are shown in FIGS. 4 to 10. Note that the spaces are through-holes
in the modified examples of FIGS. 4 to 9; however, the spaces may
of course be recesses. The spaces are recesses in the modified
example of FIG. 10.
[0034] The spaces 14 with a triangular shape are arranged in a
staggered manner in FIG. 4 and the spaces 14 with a square shape
are arranged in a staggered manner in FIG. 5. Naturally, the
staggered arrangement is not essential and, for example, the spaces
14 may be arranged in a grid pattern. In FIGS. 6 to 10, the
individual spaces are slits. In FIG. 6, the spaces 14 which extend
along one side of the second outer layer 12 are arranged in a
staggered manner. In FIG. 7, the spaces 14 which extend from along
one side of the second outer layer 12 are aligned with a side
orthogonal to this side. In FIG. 8, the spaces 14 which extend
obliquely with respect to the outer edge of the second outer layer
12 are aligned. In FIG. 9, the spaces 14 with a zigzag shape are
aligned. In FIG. 10, the spaces 14 which extend obliquely with
respect to the outer edge of the second outer layer 12 are arranged
in a network. Naturally, the shapes of the spaces 14 are not
limited these examples. For example, various shapes such as
hexagons, stars, ellipses, waveforms, arcs, and fans may be
considered.
[0035] The spaces 14 with different shapes may be mixed in one
second outer layer 12. For example, the spaces 14 with a triangular
shape may be mixed with the spaces 14 with a square shape or the
spaces 14 with a circular shape may be mixed with the spaces 14
with a slit shape. Furthermore, through-holes and recesses may be
mixed in one second outer layer 12. Moreover, the sizes of the
individual spaces 14 in one second outer layer 12 may be different.
For example, the circular spaces 14 with a diameter of 1 cm may be
mixed with the circular spaces 14 with a diameter of two cm.
[0036] The ratio of the region of the spaces 14 to the entirety of
the second outer layer 12, that is, the porosity, is not limited.
The porosity may, for example, be in a range of 50 to 80%. Since
there may also be cases where the shapes or sizes of the spaces 14
in one second outer layer are different, the porosity may change
according to the position of the region which is the target of the
calculation. For example, the porosity in the vicinity of a
peripheral section in one second outer layer 12 may possibly be 50%
whereas the porosity in the vicinity of the center may possibly be
70%.
[0037] Next, an application example of the polishing cushion 10
will be shown using FIGS. 11 to 14. FIGS. 11 and 12 are an example
where the polishing cushion 10 is applied to a portable grinder 20.
In this example, the polishing member is a polishing disk 21 and
the support member is a pad 22. The polishing cushion 10 is
processed to match shapes of the polishing disk 21 and the pad 22
and a through-hole is formed in the center thereof. The polishing
cushion 10 is detachably attached to the portable grinder 20 in the
same manner as the polishing disk 21 and the pad 22. As shown in
FIG. 12, a user plugs these three components into a shaft 23, which
extends from the main body of the portable grinder 20, in order of
the pad 22, the polishing cushion 10, and the polishing disk 21.
Thereafter, the user fixes the pad 22, the polishing cushion 10,
and the polishing disk 21 to the shaft 23 by tightening a nut 24
onto a male screw which is formed at an end section of the shaft
23.
[0038] FIGS. 13 and 14 are an example where the polishing cushion
10 is attached to a polishing wheel 30. In this example, the
polishing member is an endless polishing belt 31 and the support
member is a wheel 32. FIG. 14 shows a plurality of the polishing
cushions 10 shorter than the outer circumference of the wheel 32
(for example, eight polishing cushions 10 whose length is 1/8 of
the outer circumference). However, the polishing cushions 10 may be
endless (that is, ring-shaped). The polishing cushion 10 is
detachably attached onto the outer circumferential surface of the
wheel 32. If the plurality of polishing cushions 10 are attached as
shown in FIG. 14, an adhesive layer or a bonding layer is further
formed on the outer layer (second outer layer 12 in FIG. 14) of the
polishing cushion 10 facing the wheel 32. In such a case, the user
attaches the endless polishing belt 31 to the wheel 32 after the
polishing cushion 10 is affixed to the outer circumferential
surface of the wheel 32. If the polishing cushion 10 is endless
(ring-shaped), the user first fits the polishing cushion 10 into
the wheel 32 and then attaches the endless polishing belt 31 to the
wheel 32.
[0039] It is also possible to apply the polishing cushion 10 to a
single action sander 40A shown in FIG. 15 or a double action sander
40B shown in FIG. 16. These polishing apparatuses 40A and 40B each
include a common polishing pad 41 shown in detail in FIG. 17. In
the polishing pad 41, the polishing member is a polishing disk 42
and the support member is a pad 43. The polishing cushion 10 is
processed to match the shapes of the polishing disk 42 and the pad
43. The polishing cushion 10 is detachably attached to the single
action sander 40A or the double action sander 40B. As shown in FIG.
17, the user attaches the pad 43 to a shaft 44 extending from the
main body of the polishing apparatus 40A or 40B, the polishing
cushion 10 is affixed to the pad 43, and the polishing disk 42 is
affixed to the polishing cushion 10. Note that it is possible to
realize the affixing using a surface fastener or an adhesive.
Through these series of operations, the pad 43, the polishing
cushion 10, and the polishing disk 42 are fixed to the shaft
44.
[0040] Regardless of the type of polishing apparatus, the polishing
cushion 10 is used in two ways. As shown in FIGS. 11 to 17, one is
in a method for attaching the polishing cushion 10 to the polishing
apparatus such that the second outer layer 12 where a plurality of
the spaces 14 are formed faces the support member (the pad 22, the
wheel 32, or the pad 43), and such that the first outer layer 11
which does not have the spaces 14 faces the polishing member (the
polishing disk 21, the endless polishing belt 31, or the polishing
disk 42). The other is in a method for attaching the polishing
cushion 10 to the polishing apparatus such that the second outer
layer 12 faces the polishing member and such that the first outer
layer 11 faces the support member.
[0041] In this manner, the types of the polishing apparatus and the
ways of using the polishing cushion are varied. In any cases, the
user polishes an object using the polishing apparatus where the
polishing cushion 10 is arranged between the polishing member and
the support member. The polished object is provided as it is as an
article or as a part of an article.
[0042] When the user polishes the workpiece surface by applying the
surface of the polishing member against the object, the inner layer
13 of the polishing cushion 10, which is disposed between a
polishing member 50 and a support member 60, enters the spaces 14
which are formed in the second outer layer 12 as shown in FIG. 18.
As shown in the middle part of FIG. 18, in a case where the user
applies the polishing member 50 against the object at a pressure of
a degree at which the spaces 14 are not completely packed (that is,
a relatively low pressure), it is possible to weakly apply the
polishing member 50 against the workpiece surface since the inner
layer 13 acts as a buffer for this pressure and it is possible to
finely finish the surface as a result. On the other hand, as shown
in the lower part of FIG. 18, in a case where the user applies the
polishing member 50 against the object at a pressure of a degree at
which the spaces 14 are completely packed with the inner layer 13
(that is, a relatively high pressure), the inner layer 13
substantially does not act as a buffer for the pressure since the
inner layer 13 is almost completely crushed between the first outer
layer 11 and the second outer layer 12 and the spaces 14 are packed
with the inner layer 13. As a result, it is possible to intensively
polish the surface of the object by transferring almost all of the
pressure to the polishing member 50.
[0043] Since the inner layer substantially does not change shape in
the polishing cushion which does not have spaces which the soft
inner layer is able to enter, the result is that the inner layer
substantially does not act as a buffer for the pressure. As a
result, even though it is possible to intensively polish the
object, it is difficult to finely finish the workpiece surface. On
the other hand, according to the present embodiment, it is possible
to realize a plurality of types of polishing with the single
polishing apparatus by providing the spaces 14 which the soft inner
layer 13 enters in the second outer layer 12.
[0044] As described above, a polishing cushion according to one
aspect of the present invention includes: a first outer layer
facing one out of a polishing member and a support member; a second
outer layer facing the other out of the polishing member and the
support member; an inner layer positioned between the first outer
layer and the second outer layer; and a plurality of spaces formed
in the second outer layer which the inner layer is able to enter,
in which a hardness of the inner layer is lower than both of the
hardness of the first outer layer and the hardness of the second
outer layer.
[0045] Furthermore, a polishing apparatus according to one aspect
of the present invention includes: the polishing cushion; the
polishing member; and the support member described above.
[0046] Moreover, a polishing method according to one aspect of the
present invention is a polishing method which uses the polishing
apparatus and includes: polishing an object using the polishing
apparatus where a polishing cushion is arranged between the
polishing member and the support member, in which the polishing
cushion includes a first outer layer facing one out of the
polishing member and the support member; a second outer layer
facing the other out of the polishing member and the support
member; an inner layer positioned between the first outer layer and
the second outer layer; and a plurality of spaces formed in the
second outer layer which the inner layer is able to enter, and a
hardness of the inner layer is lower than both of the hardness of
the first outer layer and the hardness of the second outer
layer.
[0047] Furthermore, an article according to an aspect of the
present invention includes an object which is polished using the
polishing method described above.
[0048] In this aspect, when pressure is applied to the polishing
member during polishing, a part of the soft inner layer enters the
spaces due to the pressure. In a case where the polishing member is
applied to the object at a pressure of a degree at which the spaces
are not entirely packed with the inner layer (that is, at a
relatively low pressure), it is possible to finely finish the
surface by lightly applying the polishing member to the workpiece
surface since the inner layer acts as a buffer for the pressure. On
the other hand, in a case where the polishing member is applied to
the object at a pressure of a degree at which the individual spaces
are packed with the inner layer (that is, at a relatively strong
pressure), it is possible to intensively polish the workpiece
surface by transferring almost all of the pressure to the polishing
member since the inner layer is almost completely crushed and
substantially does not act as a buffer for the pressure. In this
manner, it is possible to realize a plurality of types of polishing
with a single polishing apparatus by providing spaces which the
soft inner layer enters in the outer layer.
[0049] In another aspect of the present invention, the first outer
layer which does not have the spaces which the inner layer is able
to enter may face the polishing member, and the second outer layer
may face the support member. By providing no spaces in the first
outer layer facing the polishing member, it is possible to polish
the workpiece surface without patches since the pressure which is
applied to the polishing cushion is transferred from the first
outer layer to the polishing member almost uniformly.
[0050] In another aspect of the present invention, the surface of
the second outer layer where opening sections of a plurality of
spaces are formed may be bonded with the inner layer. In such a
case, since nothing is interposed between the inner layer and the
opening sections, it is easy for the inner layer to enter the
spaces and it is easy to adjust the thickness of the inner layer
for this part.
[0051] In another aspect of the present invention, the plurality of
spaces may be through-holes. Since it is possible to increase the
volume of the inner layer which enters the spaces to the maximum by
setting the spaces as through-holes, it is easy to apply a
relatively low pressure to the polishing member. Furthermore, since
it is easy to form the through-holes in comparison with a case of
forming the recesses, it is possible to easily manufacture the
polishing cushion in this respect.
EXAMPLES
[0052] While the present invention is described more specifically
based on a working example hereinafter, the present invention is
not at all limited thereto.
[0053] As the working example, a polishing cushion with three
layers equivalent to the polishing cushion 10 described above was
prepared. The main raw material of the first outer layer and the
second outer layer was a chloroprene rubber and the main raw
material of the inner layer was also chloroprene rubber. In the
working example, the hardnesses of both of the first outer layer
and the second outer layer were 50 according to the standards of
the Type A durometer and the hardness of the inner layer was five
according to the standards of the Type E durometer. Furthermore,
the thicknesses of the first outer layer and the second outer layer
were 2 mm and the thickness of the inner layer was 3 mm. A
plurality of spaces formed in the second outer layer were circular
through-holes and the through-holes were lined up in a staggered
manner. The porosity was set to 50 to 80%.
[0054] On the other hand, as a comparative example, a polishing
cushion with two layers formed of one outer layer which did not
have spaces (equivalent to the first outer layer 11 in the
embodiment described above) and an inner layer was prepared. The
main raw material and the hardness of each of the layers were the
same as those of the comparative example.
[0055] The configuration apart from the polishing cushion and the
polishing target object were common to the working example and the
comparative example. As the polishing apparatus, a centerless
polishing machine, Nisshinbo Hammond OD-2, manufactured by Hammond
Roto-Finish Co., Inc. of Kalamazoo, Mich., USA was used. As a
polishing belt, Trizact (trademark) 363FC A35 manufactured by the
3M Company of St. Paul, Minn., USA was adopted. The width of the
polishing belt was 5.08 cm (two inches). A carbon steel bar with a
diameter of 5.08 cm (two inches) was used as the polishing target
object. The pressure during the polishing was determined by a load
current (amperes) from the centerless polishing machine.
[0056] In the working example and the comparative example, the bar
was polished by the centerless polishing machine twice; once in a
case where the pressure was increased (a load current of 4 amperes)
and once in a case where the pressure was lowered (a load current
of 0.5 amperes). Note herein that the high pressure was a pressure
of a degree at which the spaces inside the second outer layer are
completely packed with the inner layer in the working example
(refer to the lower part of FIG. 18) and that the low pressure was
a pressure of a degree at which a part of the spaces inside the
second outer layer are not packed with the inner layer in the
working example (refer to the middle part of FIG. 18). In both of
the working example and the comparative example, the polishing time
was 1.5 seconds per 5.08 cm (two inches, that is, length equivalent
to the width of the polishing belt) in the length direction of the
bar. FIG. 19 shows the results of the polishing with two aspects of
the polishing amount and the surface finishing. The polishing
amounts were determined according to the reduction amount in the
diameter of the bar and the finishing of the surface was determined
by the surface roughness (specifically, the arithmetic mean
roughness (Ra)).
[0057] The present invention has been described in detail with
respect to the embodiments thereof. However, the present invention
is not limited to the embodiments described above. Various
modifications may be made to the present invention to the extent
that they do not depart from the gist of the present invention.
[0058] In the embodiment described above, the polishing cushion 10
has a three-layer structure; however, the polishing cushion may
have four or more layers. However, an adhesive layer for affixing
the first outer layer to the inner layer and an adhesive layer for
affixing the second outer layer to the inner layer are not included
as layers. That is, a separate layer apart from the adhesive layer
may be present between the first outer layer and the inner layer or
between the second outer layer and the inner layer. However, it is
necessary for a layer which is present between the outer layer
where the spaces are formed and the inner layer to be thinned or
softened to an extent that the layer does not interfere with the
entry of the inner layer into the spaces. Alternatively, a separate
layer may be stuck to the outer side of the first outer layer and a
separate layer may be stuck to the outer side of the second outer
layer.
[0059] In the embodiment described above, the spaces 14 are only
formed in the second outer layer 12. However, the spaces into which
the inner layer enters may be formed in both of the first outer
layer and the second outer layer. In such a case, the shapes,
dimensions, and locations of the spaces may be the same in the
first outer layer and the second outer layer or may be
different.
[0060] When using the polishing cushion 10, a separate member may
be interposed between the polishing cushion 10 and the polishing
member, or a separate member may be interposed between the
polishing cushion 10 and the support member. That is, the outer
surface of the polishing cushion 10 need not contact the polishing
member or the support member.
REFERENCE NUMERALS
[0061] 10 POLISHING CUSHION [0062] 11 FIRST OUTER LAYER [0063] 12
SECOND OUTER LAYER [0064] 13 INNER LAYER [0065] 14 SPACE [0066] 14a
through-hole (SPACE) [0067] 14b RECESS (SPACE) [0068] 21 POLISHING
DISK (POLISHING MEMBER) [0069] 22 PAD (SUPPORT MEMBER) [0070] 31
ENDLESS POLISHING BELT (POLISHING MEMBER) [0071] 32 WHEEL (SUPPORT
MEMBER) [0072] 42 POLISHING DISK (POLISHING MEMBER) [0073] 43 PAD
(SUPPORT MEMBER) [0074] 50 POLISHING MEMBER [0075] 60 SUPPORT
MEMBER
* * * * *