U.S. patent application number 10/503528 was filed with the patent office on 2005-07-28 for rotary tool and its cutting part.
This patent application is currently assigned to Sanwa Kenma, Ltd.. Invention is credited to Amamoto, Hirofumi.
Application Number | 20050164620 10/503528 |
Document ID | / |
Family ID | 27736461 |
Filed Date | 2005-07-28 |
United States Patent
Application |
20050164620 |
Kind Code |
A1 |
Amamoto, Hirofumi |
July 28, 2005 |
Rotary tool and its cutting part
Abstract
A rotary tool (T) has a rotary segment (10) with an opposed
surface opposed to a work surface and a plurality of cutting parts
(20) arranged on the opposed surface. Some cutting parts (20)
include tips (22a) made of a grinding tool segment obtained by
binding abrasive grains by a metal binder and the other cutting
parts (20) include tips (24a) made of a sintered material harder
than the grinding tool segment, and the respective cutting parts
(20) are arranged such that the tips (24a) are located at positions
more outward than the tips (22a) with respect to radial directions
of the rotary segment.
Inventors: |
Amamoto, Hirofumi;
(Hirakata-shi, JP) |
Correspondence
Address: |
CASELLA & HESPOS
274 MADISON AVENUE
NEW YORK
NY
10016
|
Assignee: |
Sanwa Kenma, Ltd.
22-1 Kaminayama, Okubocho
Uji-shi
JP
611-0033
|
Family ID: |
27736461 |
Appl. No.: |
10/503528 |
Filed: |
August 4, 2004 |
PCT Filed: |
July 25, 2002 |
PCT NO: |
PCT/JP02/07529 |
Current U.S.
Class: |
451/548 |
Current CPC
Class: |
B23C 2250/21 20130101;
B23C 5/006 20130101; B23C 5/18 20130101; B44D 3/16 20130101 |
Class at
Publication: |
451/548 |
International
Class: |
B24B 005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 8, 2002 |
JP |
2002-32283 |
May 16, 2002 |
JP |
2002-141746 |
Claims
1. A cutting part for use in a rotary tool including a rotary
segment having an opposed surface opposed to a work surface,
comprising a tip for scratching off a surface portion of the work
surface when the rotary segment is pressed against the work surface
while being drivingly rotated about an axis extending in a
direction normal to the opposed surface, wherein an inner part of
the tip with respect to a radial direction is made of a grinding
tool segment obtained by binding abrasive grains by a metal binder
and an outer part of the tip with respect to the radial direction
is made of a sintered material harder than the grinding tool
segment.
2. A cutting part according to claim 1, wherein the outer part of
the tip with respect to the radial direction is made of a
polycrystalline diamond sintered material or polycrystalline cubic
boron nitride sintered material.
3. A cutting part according to claim 1, wherein the entire tip
excluding the tip part made of the sintered material is made of a
grinding tool segment obtained by binding abrasive grains by a
metal binder.
4. A cutting part according to claim 1, wherein the length of the
tip made of the sintered material is set within a range of 1% to
67% of the entire length of the tip.
5. A rotary tool, comprising: a rotary segment having an opposed
surface opposed to a work surface; and a plurality of cutting parts
arranged on the opposed surface and each having a tip for
scratching off a surface portion of the work surface in a
peripheral direction, the rotary tool scratching off the surface
portion of the work surface by pressing the respective cutting
parts against the work surface while the rotary segment is
drivingly rotated about an axis extending in a direction normal to
the opposed surface, wherein: the opposed surface is arranged with
a grinding tool segment obtained by binding abrasive grains by a
metal binder; each of the cutting parts includes a tip made of a
sintered material harder than the grinding tool segment; and the
tip made of the sintered material is provided at a position more
outward than the grinding tool segment with respect to radial
direction of the rotary segment.
6. A rotary tool according to claim 5, wherein some cutting parts
include tips made of the grinding tool segment and the other
cutting parts include tips made of the sintered material harder
than the grinding tool segment, and the respective cutting parts
are arranged such that the tips made of the sintered material are
located at positions more outward than the tips made of the
grinding tool segment with respect to the radial directions of the
rotary segment.
7. A rotary tool according to claim 5, wherein the grinding tool
segment has such a shape continuous along a peripheral direction of
the rotary segment, and the cutting parts having the tips made of
the sintered material are provided at positions more outward than
the grinding tool segment with respect to the radial directions of
the rotary segment.
8. A rotary tool, comprising: a rotary segment having an opposed
surface opposed to a work surface; and a plurality of cutting parts
arranged on the opposed surface and each having a tip for
scratching off a surface portion of the work surface in a
peripheral direction, the rotary tool scratching off the surface
portion of the work surface by pressing the respective cutting
parts against the work surface while the rotary segment is
drivingly rotated about an axis extending in a direction normal to
the opposed surface, the plurality of cutting parts including at
least one cutting part having a tip whose inner part with respect
to the radial direction is made of a grinding tool segment obtained
by binding abrasive grains by a metal binder and whose outer part
with respect to the radial direction is made of a sintered material
harder than the grinding tool segment.
9. (canceled)
10. A rotary tool according to claim 8, wherein the plurality of
cutting parts include a first cutting part having a tip made of
sintered material and a second cutting part having a tip made of
grinding tool segment, the second cutting part being arranged such
that the tip thereof is located at a position more inward than the
tip of the first cutting part made of sintered material with
respect to the radial direction of the rotary segment.
11. A rotary tool according to claim 8, wherein all the cutting
parts of the rotary tool are cutting parts have a tip whose inner
part with respect to the radial direction is made of a grinding
tool segment obtained by binding abrasive grains by a metal binder
and whose outer part with respect to the radial direction is made
of a sintered material harder than the grinding tool segment.
12. A rotary tool according to claim 11, wherein the outer part of
the tip with respect to the radial direction is made of a
polycrystalline diamond sintered material or polycrystalline cubic
boron nitride sintered material.
13. A rotary tool according to claim 11, wherein the entire tip
excluding the tip part made of the sintered material is made of a
grinding tool segment obtained by binding abrasive grains by a
metal binder.
14. A rotary tool according to claim 11, wherein the length of the
tip made of the sintered material is set within a range of 1% to
67% of the entire length of the tip.
15. A rotary tool according to claim 11, wherein all the cutting
parts having a tip whose inner part with respect to the radial
direction is made of a grinding tool segment obtained by binding
abrasive grains are peripherally arranged at even intervals.
16. A rotary tool according to claim 8, wherein the outer part of
the tip with respect to the radial direction is made of a
polycrystalline diamond sintered material or polycrystalline cubic
boron nitride sintered material.
17. A rotary tool according to claim 8, wherein the entire tip
excluding the tip part made of the sintered material is made of a
grinding tool segment obtained by binding abrasive grains by a
metal binder.
18. A rotary tool according to claim 8, wherein the length of the
tip made of the sintered material is set within a range of 1% to
67% of the entire length of the tip.
Description
TECHNICAL FIELD
[0001] The present invention relates to a rotary tool and a cutting
part thereof for working outer surfaces of walls and floors of
buildings, ships, bridges and the like to remove paints, adhesives
and the like adhered to the outer surfaces.
BACKGROUND ART
[0002] A rotary grinder in which a plurality of grinding tool
segments are arranged at the outer periphery of a saucer-shaped
rotary segment is known as a tool for working surfaces such as
floor surfaces and wall surfaces of various structures. The
respective grinding tool segments used to form this grinder are
obtained by sintering, for example, a mixture of a certain amount
of diamond abrasive grains and a metal binder. A work surface can
be abraded by bringing the respective grinding tool segments
provided on the grinder into contact with the work surface while
rotating the entire grinder at high speed.
[0003] However, in the case of using the above grinder to remove
old films adhered, for example, to floor surfaces and wall surfaces
(particularly rubber-made elastic paints and adhesives) in a repair
and renovation work or the like for a concrete structure, the films
and the like may be thermally fused and melt by friction heat
created between the films and the respective grinding tool segments
to consequently cause adhesion to the grinding tool segments, with
the result that a satisfactory removing work may not be able to be
performed. Further, there is a problem of being difficult to
produce a longer tool life because the abrasion speed of the
grinding tool segments is relatively high.
[0004] Japanese Unexamined Patent Publication No. 7-185923
discloses a rotary tool in which a plurality of cutting devices
made of sintered diamond are peripherally fixed at even intervals
on a cutting-device mounting surface defined at the outer periphery
of a saucer-shaped rotary segment. According to this tool, a work
surface can be smoothly removed without the adhesion by pressing
the respective cutting devices against the work surface while the
rotary segment is mounted on a drive shaft of a motor and rotated
at high speed.
[0005] However, the tool disclosed in the above publication has a
problem that tips made of the sintered diamond deeply cut into the
work surface since the tips have good cutting quality. Such
excessive cutting-in of the tips leaves cutting marks even in the
substrate of the work surface and shortens the tip life due to a
damage or breakage by giving an unnecessary load to the tips.
[0006] Accordingly, an object of the present invention is to enable
a satisfactory removing work by preventing an occurrence of heat
adhesion while avoiding excessive cutting-in of tips.
DISCLOSURE OF THE INVENTION
[0007] In order to solve the above object, the present invention
adopts the follow construction.
[0008] Specifically, the present invention is directed to a cutting
part of a rotary tool provided on an opposed surface of a rotary
segment of the rotary tool opposed to a work surface and having a
tip for scratching off a surface portion of the work surface when
the rotary segment is pressed against the work surface while being
drivingly rotated about an axis extending in a direction normal to
the opposed surface, wherein an inner part of the tool segment with
respect to a radial direction is made of a grinding tool segment
obtained by binding abrasive grains by a metal binder and an outer
part of the tip with respect to the radial direction is made of a
sintered material harder than the grinding tool segment (claim
1).
[0009] In this cutting part, the radially outer part of the tip,
i.e. a part thereof performing more cutting work due to its higher
peripheral speed, is made of the hard sintered material having a
sharp cutting quality. Thus, the surface portion of the work
surface can be lightly removed at high speed by this part, thereby
preventing an occurrence of heat adhesion. On the other hand, the
radially inner part of the tip, i.e. a part thereof performing less
cutting work due to its lower peripheral speed, is made of the
grinding tool segment (grinding tool segment obtained by binding
the abrasive grains by the metal binder) having a relatively dull
cutting quality due to its lower hardness than the sintered
material. This can prevent the entire tip from cutting in
excessively deep.
[0010] Further, by making the radially outer part of the tip
performing more cutting work of the sintered material while making
the radially inner part thereof performing less cutting work of the
grinding tool segment, the wear speed of the tip can be made
uniform over the entire radial direction. Thus, unlike the prior
technology cutting part whose tool segment is entirely made of the
same material, wear of the radially outer part of the tool segment
prior to the radially inner part thereof can be prevented from
occurring. As a result, the entire tool life can be extended.
[0011] Further, surface residues of the covering materials which
could not be removed by the tip part made of the hard sintered
material can be supplementarily ground off by the grinding edges
made of the grinding tool segment. Furthermore, even if the removal
by the tip part made of the sintered material leaves scratches on
the work surface, such scratches can be ground-off or finished by
the grinding edges made of the grinding tool segment.
[0012] For example, cemented carbide, ceramic, cermet and the like
may be used as the hard sintered material. However, a
polycrystalline diamond sintered material (PCD) and a
polycrystalline cubic boron nitride sintered material (PCBN) are
particularly preferable (claim 2). By using such a particularly
hard sintered material, adhesion can be more securely prevented
from occurring and a longer tool life can be given.
[0013] Further, Diamond abrasive grains and CBN abrasive grains are
preferably used as the abrasive grains to be bound by the metal
binder.
[0014] Japanese Unexamined Utility Model Publication No. 3-7470
discloses a cutter bit in which metal-bonded diamond grinding tool
segments and cemented carbides are alternately arranged in order to
cut reinforced concrete. Since the grinding tool segments and the
cemented carbides are arranged in peripheral direction (not in
radial directions), an effect of preventing an occurrence of
adhesion while preventing excessive cutting-in of the tip as in the
present invention cannot be obtained.
[0015] According to the present invention, not only the radially
inner part of the tip, but also the entire tip excluding the tip
part made of the sintered material are more preferably made of a
grinding tool segment obtained by binding abrasive grains by a
metal binder (claim 3). With such a tip, the aforementioned effects
can be obtained while the construction of the entire cutting part
is simplified.
[0016] According to the present invention, a ratio of the length of
the tip part (radially outer part) made of the hard sintered
material to that of the remaining part (radially inner part) may be
suitably selected based on the materials and rotating speeds of the
respective parts. Generally, the length of the tip made of the
sintered material is preferably set within a range of 1% to 67% of
the entire length of the tip in order to enjoy both the adhesion
preventing effect and the excessive cutting-in preventing effect
(claim 4).
[0017] The present invention is also directed to a rotary tool,
comprising: a rotary tool segment having an opposed surface opposed
to a work surface, and a plurality of cutting parts arranged on the
opposed surface and each having a tip for scratching off a surface
portion of the work surface in a peripheral direction, the rotary
tool scratching off the surface portion of the work surface by
pressing the respective cutting parts against the work surface
while the rotary tool segment is drivingly rotated about an axis
extending in a direction normal to the opposed surface, wherein a
grinding tool segment obtained by binding abrasive grains by a
metal binder is arranged on the opposed surface; the cutting parts
include tips made of a sintered material harder than the grinding
tool segment; and the tips made of the sintered material are
provided at positions more outward than the grinding tool segment
with respect to radial directions of the rotary tool (claim 5).
[0018] With this rotary tool, while the tips made of the hard
sintered material and having a sharp cutting quality lightly remove
the surface coverings of the work surface at high speed to prevent
an occurrence of heat adhesion, the presence of the grinding tool
segment having a lower hardness than the sintered material and a
relatively dull cutting quality at the position radially inward of
these tips suppresses deep cutting-in of the entire tip. Further,
the removing work by the tips made of the hard sintered material is
assisted by the grinding tool segment. If the work surface is
scratched by the removing work by the tips made of the sintered
material, such scratches can be ground off or finished by the
grinding tool segment.
[0019] As a specific embodiment of this rotary tool, some cutting
parts include tips made of the grinding tool segment and the other
cutting parts include tips made of the sintered material harder
than the grinding tool segment, and the respective cutting parts
are arranged such that the tips made of the sintered material are
located at positions more outward than the tips made of the
grinding tool segment with respect to the radial directions of the
rotary segment (claim 6). As another specific embodiment, the
grinding tool segment has such a shape continuous along a
peripheral direction of the rotary segment, and the cutting parts
having the tips made of the sintered material are provided at
positions more outward than the grinding tool segment with respect
to the radial directions of the rotary segment (claim 7).
[0020] The present invention is further directed to a rotary tool,
comprising a rotary segment having an opposed surface opposed to a
work surface, and a plurality of cutting parts arranged on the
opposed surface and each having a tip for scratching off a surface
portion of the work surface in a peripheral direction, the rotary
tool scratching off the surface portion of the work surface by
pressing the respective cutting parts against the work surface
while the rotary segment is drivingly rotated about an axis
extending in a direction normal to the opposed surface, wherein at
least a part of the cutting parts are cutting parts according to
any one of claims 1 to 4 (claim 8).
[0021] With this rotary tool, while the tips made of the hard
sintered material and having a sharp cutting quality lightly remove
the surface portion of the work surface at high speed to prevent an
occurrence of heat adhesion, the presence of the tips made of the
grinding tool segment having a lower hardness than the sintered
material and a relatively dull cutting quality suppresses deep
cutting-in of the tips. Further, the removing work by the tips made
of the hard sintered material is assisted by the tips made of the
grinding tool segment. If the work surface is scratched by the
removing work by the tips made of the sintered material, such
scratches can be ground off or finished by the tips made of the
grinding tool segment.
[0022] In the rotary tool according to claim 8, all the cutting
parts of the rotary tool may not be necessarily cutting parts
according to any one of claims 1 to 4. However, if all the cutting
parts are cutting parts according to any one of claims 1 to 4 and
peripherally arranged at even intervals (claim 9), a smoother
removing work can be realized by making the cutting ability
peripherally uniform.
[0023] Further, if the rotary tool comprises at least first cutting
parts having tips made of the sintered material and second cutting
parts having tips made of the grinding tool segment, and the second
cutting parts are arranged such that the tips thereof are located
at positions more inward than the tips of the first cutting parts
made of the sintered material with respect to the radial directions
of the rotary segment (claim 10), both the backing preventing
effect and the excessive cutting-in preventing effect can be
enjoyed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a perspective view of a rotary tool according to a
first embodiment of the present invention when viewed from
bottom;
[0025] FIG. 2 is a perspective view of the rotary tool when viewed
from above;
[0026] FIG. 3 is a side view of the rotary tool;
[0027] FIG. 4 is a perspective view showing an exemplary driving
device on which the rotary tool is mounted;
[0028] FIG. 5 is a perspective view of the rotary tool of the
embodiment of the present invention constructed to work painted
floors when viewed from bottom;
[0029] FIG. 6 is a perspective view of a rotary tool according to a
second embodiment of the present invention when viewed from
bottom;
[0030] FIG. 7 is a bottom view of the rotary tool of FIG. 6;
[0031] FIG. 8 is a perspective view of a rotary tool according to a
third embodiment of the present invention when viewed from
bottom;
[0032] FIG. 9 is a bottom view of the rotary tool of FIG. 8;
[0033] FIG. 10 is a bottom view of a rotary tool according to a
fourth embodiment of the present invention; and
[0034] FIGS. 11A and 11B are a bottom view and a front view in
section of a rotary tool according to a fifth embodiment of the
present invention.
BEST MODES FOR CARRYING OUT THE INVENTION
[0035] A first embodiment of the present invention is described
with reference to the accompanying drawings. Although a case where
a film applied to the outer surface of a work surface S is to be
removed is illustrated in this embodiment, working according to the
present invention is not limited thereto. The present invention is
also widely applicable to removal of other "films" such as
adhesives, resin sheets and resin tiles adhered to work surfaces or
work surfaces made of other materials.
[0036] A rotary tool T shown in FIGS. 1 to 4 is comprised of a
rotary segment 10 made of a metallic plate and a plurality of
cutting parts 20 mounted on the rotary segment 10.
[0037] The rotary segment 10 integrally includes an outer
peripheral portion 11 in the form of a flat plate 11 and an inner
portion 12 formed inside the outer peripheral portion 11.
[0038] The inner portion 12 bulges out upward substantially in the
form of a cone from the inner edge of the outer peripheral portion
11, and a flat portion 14 parallel with the outer peripheral
portion 11 is formed in a middle part of the inner portion 12. A
driving-shaft insertion hole 18 is formed in the center of the flat
portion 14, and a driving shaft of an unillustrated driving source
is mounted into the insertion hole 18 to drive the entire rotary
tool about a center axis O (see FIG. 2) together with the driving
shaft. A plurality of through holes 17 are peripherally formed at
an outward-bulging portion (i.e. a portion between the center axis
O and the outer peripheral portion 11) radially outward of the flat
portion 14.
[0039] The bottom surface of the outer peripheral portion 11 is a
surface (hereinafter, merely "opposed surface") opposed to the work
surface S shown in FIG. 3 in parallel therewith, and a plurality of
cutting parts 20 are peripherally arranged on this opposed surface.
In the shown example, eight cutting parts 20 are peripherally
arranged at even intervals, and secured to the opposed surface by
means of brazing and screwing.
[0040] Each cutting part 20 includes a cutting-part main body 22
and a hard sintered material partially secured to the cutting-part
main body 22 via a cemented carbide 23.
[0041] Each cutting-part main body 22 is in the form of a block
obtained by combining abrasive grains (e.g. diamond abrasive grains
or CBN abrasive grains) by a metal binder (e.g. iron, cobalt,
tungsten, or the like). In the shown example, each cutting-part
main body 22 has an outer peripheral surface substantially arcuate
in bottom view and extending along the outer periphery of the outer
peripheral portion 11, an inner peripheral surface substantially
arcuate in bottom view and extending along the inner periphery of
the outer peripheral portion 11, and opposite side surfaces
straight in bottom view and extending in radial directions of the
tool T, and has uniform thickness in its entirety. In each
cutting-part main body 22, a part located at a downstream side with
respect to rotating direction and at an outer side with respect to
radial direction locally is cut off, and the cemented carbide 23
and the hard sintered material 24 shaped to complement for a
cut-off part are secured to this cut-off part.
[0042] It is sufficient to make the hard sintered material 24 of a
sintered material harder than the cutting-part main body 22. For
example, cemented carbide, ceramic, cermet or the like may be used.
Particularly preferably used are a polycrystalline diamond sintered
material having excellent hardness and a polycrystalline cubic
boron nitride sintered material having hardness next to the former
material. A preferable method for forming such hard sintered
materials 24 and securing them to the cutting-part main bodies 22
is, for example, such that diamond powder as a raw material of the
hard sintered material 24 is placed on the outer surface of a
substrate made by the cemented carbide 23 and pressurized, whereby
the entirety is integrally sintered to produce a tool material made
of diamond sintered material, and this tool material is cut to a
shape corresponding to the cut-off part and a surface of the cut
tool material at the side of the cemented carbide 23 is secured to
the cutting-part main body 22 by brazing.
[0043] With the hard sintered material 24 secured to the
cutting-part main body 22, a bottom edge 24a of the hard sintered
material 24 at a downstream side with respect to radial direction
and a bottom edge 22a of the cutting-part main body 22 at a
downstream side with respect to radial direction are aligned in a
straight line. The bottom edge 24a of the hard sintered material 24
forms an outer part of a tip with respect to radial direction,
whereas the bottom edge 22a of the cutting-part main body 22 forms
an inner part of the tip with respect to radial direction.
[0044] Although a tip angle is 90.degree. and a rake angle is
0.degree. in the shown example, these angles may be suitably set
according to the specific material and application of the
cutting-part.
[0045] A ratio of entire tip length Lo to length Ls of the bottom
edge 24a as shown in FIG. 1 depends on the material of the hard
sintered material 24. This ratio is preferably 1% to 67% if the
hard sintered material 24 is made of a polycrystalline diamond
material or polycrystalline cubic boron nitride sintered material.
There is a high chance of adhesion if this ratio is below 1%,
whereas problems caused by excessive cutting-in are likely to occur
if this ratio exceeds 67%.
[0046] Although the thickness of the hard sintered material 24 may
be smaller than that of the cutting-part main body 22, the lift of
the cutting part 20 can be maximally extended by equally setting
the two thicknesses.
[0047] Next, the use and functions of this tool T are
described.
[0048] 1) Mounting onto a Driving Device
[0049] First, the tool T is mounted onto a driving device. A
portable driving device 30 is shown in FIG. 4 as an example. This
driving device 30 includes a grip 32 and a tool cover 36 provided
at the leading end of the grip 32, an unillustrated drive shaft
projects in the tool cover 36 and a motor or the like for rotating
this drive shaft at high speed is built in a driving device main
body. Further, the tool cover 36 is connected with an unillustrated
exhaust pump via an air pipe 34.
[0050] The rotary segment 10 is connected and fixed at the leading
end of the drive shaft, for example, by inserting the drive shaft
of this driving device 30 through the insertion hole 18 formed in
the tool T and mounting a nut on an externally threaded portion
formed at the leading end of the drive shaft. In this way, the
entire tool T is mounted in the tool cover 36 shown in FIG. 4 and
has its rear side (side opposite from the work surface S) covered
by the tool cover 36.
[0051] 2) Working by the Tool T
[0052] The grip 32 of the driving device 30 is gripped while the
drive shaft and the tool T are integrally rotated at high speed and
air is exhausted inside the tool cover 36 via an unillustrated
exhaust pipe, and the respective cutting parts 20 are pressed
against the work surface (e.g. wall surface) S and moved along the
work surface S. In this way, the coverings on the work surface S is
scratched off by the tips of the respective cutting parts 20
rotating at high speed.
[0053] Here, since the outer part of the tip with respect to radial
direction, i.e. part performing more cutting work due to higher
peripheral speed is formed by the hard sintered material 24 having
a sharp cutting quality, the coverings on the work surface S can be
lightly removed by this part, whereby adhesion of the coverings due
to thermal fusion can be prevented. On the other hand, an
occurrence that the entire tips deeply cut in can be suppressed
since the inner parts of the tips with respect to radial
directions, i.e. parts performing less cutting work due to their
low rotating direction are made of metal bound grinding tool
segment (grinding tool segment forming the cutting-part main parts
22) having a relatively dull cutting quality due to its smaller
cutting edges than the sintered material.
[0054] Whereas the radially outer parts of the tips performing more
cutting work are formed by the hard sintered materials 24, the
radially inner parts of the tips performing relatively less cutting
work are formed by the above grinding tool segment (the one forming
the cutting-part main bodies 22), whereby the wear speed of the
tips can be made uniform over the entire radial direction. Unlike
the prior art cutting parts in which the entire tips are made of
the same material, the radially outer parts of the tips can be
prevented from abrasion prior to the radially inner parts thereof.
As a result, the entire tool life can be extended longer.
[0055] Further, the removing work by the tips formed by the bottom
edges 24a of the hard sintered materials 24 (hereinafter, "hard
sintered material tips 24a") can be assisted by the tips formed by
the cutting-part main bodies 22 made of grinding tool segment
(grinding tool segment tips 22a). For example, in the case of using
this tool to remove a covering, the coverings which cannot be
scratched off by the hard sintered material tips 24a can be
supplementarily scratched off by the grinding tool edges 22a.
Further, in the case of making a scratch upon the removing work by
means of the hard sintered material tips 24a, an effect of grinding
off or finishing such a scratch can be expected by the grinding
tool edges 22a.
[0056] Cutting dust produced by such scratching is sucked to the
side of the tool cover 36 (side opposite from the work surface S)
via the respective through holes 17.
[0057] Although the tool T used by being mounted on the portable
driving device 30 is shown in FIGS. 1 to 4, the present invention
is not limited thereto. For example, in the case of working a
so-called "painted floor", the film can be efficiently removed in a
comfortable posture by mounting the tool T on a hand-push type
processing device or ridable processing device which can run on the
floor. One example of the tool T for such an application is shown
in FIG. 5. In a rotary tool T shown, a rotary segment 10 is formed
into a simple disk shape, and a plurality of cutting parts 20 are
arranged at an outer peripheral portion thereof. Although a
cutting-part main body 22 is formed to be triangular in bottom view
in the shown cutting part 20, it is quite similar to the one shown
in FIGS. 1 to 4 in that a sintered material 24 is locally provided
at a radially outer part.
[0058] The work surfaces to be processed according to the present
invention are not limited to the walls and floors of buildings. For
example, the present invention can be effectively applied, for
example, to repair the paints of ships and bridges.
[0059] Although the metal binder grinding tool segment forming the
radially inner part of the tip constitutes the cutting-part main
body 22 in the shown cutting part 20, the present invention is not
limited thereto. For example, the cutting-part main body may be
made of a different material (cemented carbide, etc.), and a hard
sintered material forming the radially outer part of the tip and a
grinding tool segment (grinding tool segments obtained by combining
abrasive grains by a metal binder) forming the radially inner part
of the tip may be secured side by side to this cutting-part main
body.
[0060] According to the present invention, a plurality of cutting
parts may be arranged in two or more inner and outer rows (i.e.
arranged on a plurality of concentric circles) on an opposed
surface.
[0061] In the rotary tool according to the present invention, all
the cutting parts may not include the grinding tool segment 22a and
the hard sintered material tip 24a as the cutting parts 20 do.
First cutting parts at least including a tip made of a hard
sintered material and second cutting parts whose tip is entirely
made of grinding tool segment obtained by combining abrasive grains
by a metal binder may be provided in a mixed manner on an opposed
surface.
[0062] For example, as shown in FIGS. 6 and 7 as a second
embodiment, cutting parts (first cutting parts) 20 each including
both the grinding tool segment tip 22a and the hard sintered
material tip 24a may be peripherally intermittently arranged, and
cutting parts (second cutting parts) 26 each including only a tip
26a formed of the grinding tool segment (grinding tool segment
obtained by binding abrasive grains by a metal binder) may be
arranged between adjacent cutting parts 20. Further, as shown in
FIGS. 8 and 9 as a third embodiment, if a circumcircle C touching
tips 26a of cutting parts 26 is located inwardly of hard sintered
material tips 24a with respect to the radial directions of the
rotary segment 10, loads on the grinding tool segment tips 22a of
the respective cutting parts 20 can be mitigated by the respective
cutting parts 26.
[0063] Specifically, as shown in FIG. 10 as a fourth embodiment,
even in such a construction that cutting parts each including only
the hard sintered material tip 24a are provided at positions
radially more outward than the cutting parts 26 (cutting parts made
by the hard sintered materials 24 are secured in recesses 16 formed
in the opposed surface of the rotary segment 10 in the shown
example), i.e. even in such a construction that the grinding tool
segment tips 22a shown in FIG. 1 and other figures are deleted, the
tips 26a of the cutting parts 26a made of the grinding tool segment
can suppress excessive cutting-in, assist cutting by the tips 24a
and grind off or finish scratches caused by the cutting by the tips
24a.
[0064] Further, as shown in FIG. 11 as a fifth embodiment, the
rotary tool may be such that a grinding tool segment 28 having a
shape continuous along a peripheral direction of the rotary segment
10 (ring shape in the shown example) is provided, and cutting parts
each including the hard sintered material tip 24a are provided at
positions more outward than this grinding tool segment 28 with
respect to the radial directions of the rotary segment 10. In this
way, even if the grinding tool segment 28 has no tip, it can assist
the cutting by the hard sintered material tips 24a by its abrading
action, and the abrasion thereby can grind off or finish scratches
formed by cutting by the hard sintered material tips 24a. Of
course, an effect of preventing excessive cutting-in can also be
given.
[0065] However, if all the cutting parts are those according to the
present invention and peripherally arranged at even intervals as in
the first embodiment, cutting ability can be made uniform along
peripheral direction, thereby obtaining advantages of realizing a
smoother removing work and a longer life for the tool.
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