Abstrict A diamond blade S includes a blade portion 2a formed of diamond
abrasive grains and fixed to a base plate 1 along the outer circumferential
edge thereof. Isolated cutting elements 2b are provided on at least
a front or reverse face of the base plate 1 such that the isolated
cutting elements 2b are separated from the blade portion 2a fixed
along the outer circumferential edge.
Claims We claim:
1. A diamond blade comprising a base plate having an outer circumferential
edge, a blade portion formed of diamond abrasive grains fixed to
said base plate along said outer circumferential edge, and cutting
elements extending through said base plate and exposed at both of
opposing faces of said base plate, said cutting elements being radially
inward of and separated from said blade portion at least at one
surface of said base plate.
2. A diamond blade according to claim 1 wherein said blade portion
is formed of diamond abrasive grains and is fixed to said outer
circumferential edge of said base plate by means of direct sintering,
and recesses are formed alternately on the opposing faces of said
base plate, each of said recesses extending inward from outer circumferential
edge of the base plate and inclining radially outward opposite the
rotation direction of the base plate.
3. A diamond blade according to claim 2 wherein said cutting elements
are respectively formed on lines extending from the corresponding
recesses.
4. A diamond blade according to claim 2 wherein said blade portion
is in sections, each of said blade sections being formed of diamond
abrasive grains and located between a pair of adjacent recesses,
a first group of said blade sections extending toward the center
of the base plate further than a second group of said blade sections
and spaced at predetermined intervals between blade sections of
said second group.
5. A diamond blade according to claim 4 said first group of blade
sections are formed on both the front and the reverse faces of the
base plate.
6. A diamond blade according to claim 5 wherein said blade sections
of said first group are formed on the front and reverse faces of
the base plate with a phase difference of a predetermined angle
as measured with the rotational center of the base plate being regarded
as a reference point.
7. A diamond blade according to claim 2 wherein said blade portion
is in blade sections formed of diamond abrasive grains, wherein
said blade sections include paired blade sections, each pair sandwiching
one of said recesses on the front or reverse face of the base plate,
said paired blade sections extending further toward the center of
the base plate than other blade sections, with inner ends of the
paired blade sections connected together to form a substantially
squarish C-shape.
8. A diamond blade according to claim 7 wherein said paired blade
sections are formed on the front and reverse faces of the base plate
with a phase difference of a predetermined angle as measured with
the rotational center of the base plate being regarded as a reference
point.
9. A diamond blade according to claim 1 wherein said cutting elements
are fixed to predetermined positions of the base plate by means
of direct sintering.
10. A diamond blade according to claim 1 wherein each of said
cutting elements has a substantially trapezoidal shape which inclines
forward from an outer end thereof, with respect to the rotation
direction of the base plate.
11. A diamond blade according to claim 1 wherein crest portions
and trough portions are alternately formed on opposite faces of
the base plate, so that the base plate has opposing faces with wavy
surfaces.
Description TECHNICAL FIELD
The present invention relates to a diamond blade for cutting and
to a method of manufacturing the same, and more particularly to
a diamond blade used for cutting stone, concrete, or any other workpiece,
as well as to a method of manufacturing the same.
BACKGROUND ART
A blade used for cutting a hard material such as stone or concrete
consists of a circular base plate, and a layer of super abrasive
grains, such as diamond abrasive grains or CBN abrasive grains,
which is bonded to the outer circumferential edge of the base plate
through direct sintering, brazing, welding.
Alternatively, the blade consists of a circular base plate, and
diamond segments which are fixed to the outer circumferential edge
of the base plate at predetermined intervals.
When a workpiece; for example, a concrete member, is cut by use
of such a diamond blade, a boundary portion (hereinafter referred
to as a "neck") between the diamond-abrasive-grain layer
(or the diamond segment) and the base plate thinner than the diamond-abrasive-grain
layer (or the diamond segment) wears considerably due to swarf which
is generated during cutting and which has a strong wearing effect,
with the result that the diamond-abrasive-grain layer (or the diamond
segment) may drop from the base plate due to the neck wear, even
if the diamond grain layer (or the diamond segment) is still usable.
In order to prevent the above-described neck wear, diamond blades
as shown in FIGS. 18 and 19 have been proposed. In the diamond blade
60 shown in FIG. 18 two types of diamond segments are provided
on the outer circumferential surface of a steel base plate 61. Specifically,
there are provided a plurality of ordinary diamond segments 62 having
an arcuate shape, and a plurality of irregular-shaped diamond segments
64 whose side surfaces extend to the vicinity of the lower end of
a slot 63 formed at the outer circumference of the steel base plate
61 on the front side with respect to the rotation direction. The
ratio in number between the tips 62 and 64 is set in the range of
about 3:1 to 6:1 (West German Patent Application Laid-Open No. 3005324
discloses a diamond blade similar to that shown in FIG. 18).
In the diamond blade 70 shown in FIG. 19 a mixture of metal powder,
and diamond or CBN abrasive grains is bonded to a steel base plate
71 through sintering. Specifically, there are provided super-abrasive-grain
layers 72 and tips (each having a leg portion) 72A having a super-abrasive-grain
layer which extends toward the inner circumference of the base plate
in order to achieve prevention of neck wear and other effects. Therefore,
the diamond blade 70 can prevent neck wear. Further, when the diamond
blade 70 cuts a hard plate material or the like, the diamond blade
70 can made the cut surface smoother than can conventional diamond
blades, because the leg portion of the tip extends from the center
of the super-abrasive-grain layer toward the center of the base
plate to thereby form a T-like shape.
The diamond blade 60 shown in FIG. 18 is effective in terms of
prevention of neck wear; however, since opposite sides of the irregularly-shaped
tip 64 have a large total area, cutting resistance is high, resulting
in a deterioration in cutting performance. The diamond blade 70
shown in FIG. 19 has the following problem. When the diamond blade
70 cuts a workpiece, the workpiece or swarf strike the leg portions
of the base plate. Further, since the leg portions hinder discharge
of the swarf, the swarf stagnates between cut surfaces and the base
plate. Thus, so-called neck wear is accelerated. Further, when swarf
stagnates, rotational friction is generated between the cut surfaces
and the base plate, so that smooth rotation of the diamond blade
is hindered. Consequently, deflection occurs during rotation, resulting
in deteriorated straightness of the travel path.
The present invention was accomplished to solve the above-described
problems, and an object of the present invention is to provide a
diamond blade which can prevent neck wear and deterioration in cutting
performance simultaneously, which is inexpensive, and whose travel
path has excellent straightness, as well as a method of manufacturing
the diamond blade.
DISCLOSURE OF THE INVENTION
The present invention provides a diamond blade in which a blade
portion formed of diamond abrasive grains is fixed to a base plate
along the outer circumferential edge thereof, characterized in that
isolated cutting elements are provided on at least a front or reverse
face of the base plate such that the isolated cutting elements are
separated from the blade portion fixed along the outer circumferential
edge.
Since isolated cutting elements are provided on the base plate,
a workpiece is cut by both the isolated cutting elements and the
blade portion provided along the outer circumferential edge of the
base plate, and the flow of swarf is divided into a plurality of
flows, so that swarf does not concentrate at the neck, and thus
neck wear can be prevented. Further, since the isolated cutting
elements grind cut surfaces, the resistance generated at the side
surfaces during cutting can be reduced, and the finish of cut surfaces
is improved.
Preferably, the blade portion formed of diamond abrasive grains
is fixed to the outer circumferential edge of the base plate by
means of direct sintering, and recesses are formed alternately on
the front and reverse faces of the base plate such that each recess
extends from the outer circumferential edge of the base plate while
inclining forward with respect to the rotation direction of the
base plate. Therefore, swarf generated during cutting of a workpiece
is discharged from the recesses effectively as the diamond blade
rotates, whereby generation of rotational friction, which would
otherwise be generated due to stagnation of swarf between cut surfaces
and the base plate, can be prevented.
When, as described above, the blade portion formed of diamond abrasive
grains is fixed to the outer circumferential edge of the base plate
by means of direct sintering, the isolated cutting elements are
preferably fixed to predetermined positions of the base plate by
means of direct sintering. When formation of the blade portion of
diamond abrasive grains, formation of the isolated cutting elements,
and connection of these blade portions to the base plate are performed
by means of direct sintering, the diamond blade can be manufactured
at low cost.
Preferably, each of the isolated cutting elements has a substantially
trapezoidal shape which inclines forward from the outer end thereof
with respect to the rotation direction of the base plate, because
this configuration maintains smooth rotation of the diamond blade.
Further, the isolated cutting elements are preferably formed on
a line extending from the corresponding recess.
Preferably, each section of the blade portion formed of diamond
abrasive grains and located between the recesses has an extended
blade portion formed on the front or reverse face of the base plate,
the extended blade portion extending toward the center of the base
plate and adjacent extended blade portions being spaced at predetermined
intervals. Alternatively, adjacent sections of the blade portion
formed of diamond abrasive grains and sandwiching the corresponding
recess on the front or reverse face of the base plate are extended
toward the center of the base plate, and inner ends of the extended
sections are connected together to form a substantially squarish
C-like. shape to thereby form at least one irregular-shaped blade
portion.
When, as described above, the blade portion has an extended blade
portion or irregular-shaped blade portion, a workpiece is cut by
blade portions having different shapes, and the flow of swarf is
divided into a plurality of flows, so that swarf does not concentrate
at the neck, and thus neck wear can be prevented. Further, since
the blade portions extending toward the center side grind cut surfaces,
the finish of cut surfaces is improved.
Preferably, the isolated cutting elements, the extended blade portions,
or the irregular-shaped blade portions are formed on both the front
and the reverse faces of the base plate. In this case, the effects
of preventing neck wear and improving the finish of cut surfaces
can be attained on both the front and reverse faces of the base
plate.
At this time, the isolated cutting elements, the extended blade
portions, or the irregular-shaped blade portions are preferably
formed on the front and reverse faces of the base plate with a phase
difference of a predetermined angle as measured with the rotational
center of the base plate serving as a vertex. In this case, the
thickness of the diamond blade can be maintained constant, and therefore,
the diamond blade can be rotated smoothly. In addition, since the
flow of swarf is divided into a plurality of flows, swarf neither
concentrates nor stagnates at one location.
Preferably, crest portions and trough (recess) portions are alternately
formed on opposite faces of the base plate, so that the base plate
has a wavy surface on either face. In this case, swarf can be discharged
smoothly from the trough (recess) portions, and upon rotation of
the blade, an air-cooling effect occurs, so that accumulation of
heat at the cutting edge and the base plate can be avoided.
The present invention further provides a diamond blade in which
slots are formed in a base plate at predetermined intervals, and
a diamond segment is fixed to the outer circumferential surface
of the base plate to be located between the corresponding slots,
characterized in that each of the slots extends from the outer circumferential
edge toward the center of the base plate, while inclining forward
with respect to the rotation direction of the base plate; and the
diamond segment has an elongated portion extending along the outer
circumferential surface of the base plate and an extension portion
extending from the elongated portion along the slot located on the
front side of the elongated portion with respect to the rotation
direction, the elongated portion and the extension portion forming
an L-like shape.
As described above, the diamond blade of the present invention
has a structure such that a diamond segment is fixed to the base
plate having slots, and the diamond segment has an extension portion
extending from the elongated portion along the slot located on the
front side of the elongated portion with respect to the rotation
direction to thereby form an L-like shape. Therefore, as the amount
of intrusion of the diamond blade into a workpiece increases, the
extension portion extending along the slot comes into contact with
the workpiece, whereby cutting work proceeds.
Accordingly, the workpiece is cut and ground by means of the extension
portion, and swarf is discharged from the slots. In this manner,
swarf is prevented from entering the spaces between the base plate
and the diamond segments, and thus neck wear is prevented. In addition,
it is possible to prevent generation of rotational friction which
would otherwise be generated due to stagnation of swarf between
the base plate and the diamond segments.
Preferably, the extension portion extends up to a point in the
vicinity of the bottom of the corresponding slot. In this case,
the extension portion comes into contact with a cut surface of a
workpiece over a wider range, so that the workpiece can be cut more
efficiently. Preferably, the diamond segment has a projection extending
toward the center of the base plate in the vicinity of the rear
end with respect to the rotation direction. This structure enables
the diamond segment to be reliably fixed to the base plate.
Even in the case of the diamond blade in which a diamond segment
is fixed the base plate having slots, isolated cutting elements
are preferably formed on at least the front or the reverse face
of the base plate. In this case, the flow of swarf is divided into
a plurality of flows, so that neck wear can be prevented more effectively.
In a method of manufacturing a diamond blade according to the present
invention, the diamond blade is manufactured through so-called direct
sintering in which sintering of the diamond segment and bonding
of the diamond segment to the base plate are performed in the same
step. Therefore, production cost can be reduced greatly.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1 to 3 are front views each showing a diamond blade according
to a first embodiment of the present invention;
FIG. 4 is a front view of a diamond blade according to a second
embodiment of the present invention;
FIG. 5(a) is a front view of the diamond blade according to the
second embodiment of the present invention;
FIG. 5(b) is a top view of the diamond blade shown in FIG. 5(a);
FIG. 5(c) is a side view of the diamond blade shown in FIG. 5(a);
FIG. 6 is a back view of the diamond blade shown in FIG. 4;
FIG. 7 is a sectional view taken along line A--A of FIG. 4;
FIG. 8 is a front view of a diamond blade according to a third
embodiment of the present invention;
FIG. 9(a) is a front view of the diamond blade according to the
third embodiment of the present invention;
FIG. 9(b) is a top view of the diamond blade shown in FIG. 9(a);
FIG. 9(c) is a side view of the diamond blade shown in FIG. 9(a);
FIG. 10 is a back view of the diamond blade shown in FIG. 8;
FIG. 11 is a sectional view taken along line B--B of FIG. 8;
FIG. 12 is a front view of a diamond blade according to a fourth
embodiment of the present invention;
FIG. 13(a) is a front view of the diamond blade according to the
fourth embodiment of the present invention;
FIG. 13(b) is a top view of the diamond blade shown in FIG. 13(a);
FIG. 13(c) is a side view of the diamond blade shown in FIG. 13(a);
FIG. 14 is a back view of the diamond blade shown in FIG. 12;
FIG. 15(a) is a sectional view taken along line C--C of FIG. 12;
FIG. 15(b) is a sectional view taken along line D--D of FIG. 12;
FIG. 15(c) is a sectional view taken along line E--E of FIG. 12;
FIG. 16 is an explanatory view showing a state in which isolated
cutting elements are provided on the diamond blade of FIG. 12;
FIG. 17 is a table showing the results of an experiment performed
in relation to the fourth embodiment; and
FIGS. 18 and 19 are explanatory views showing conventional diamond
blades.
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will now described with reference
to the drawings. However, members, arrangements, etc. mentioned
in the following description do not limit the scope of the invention,
and may be changed in various ways within the scope of the present
invention.
(First Embodiment)
A diamond blade S according to the present embodiment comprises
a steel base plate 1 and blade portions 2 formed of diamond abrasive
grains. In the diamond blade S according to the present embodiment,
the blade portions 2 include a first blade portion 2a disposed along
the outer circumferential edge of the steel base plate 1 and second
blade portions 2b or isolated cutting elements separated from the
first blade portion 2a.
The steel base plate 1 is formed of carbon tool steel and has a
circular shape, and an attachment hole 1c for attachment to an unillustrated
jig is formed at the center of the steel base plate 1. The steel
base plate 1 is preferably manufactured from a special plate; e.g.,
a three-layer plate well known in the art. In this case, cutting
noise generated upon cutting stone or concrete material can be lowered
without any change in cutting performance.
A steel base plate which has crest portions having an arcuate cross
section and flat trough (recess) portions on the surface as shown
in FIG. 2 may be used as the steel base plate 1. When the steel
base plate 1 having a wavy surface is used, upon rotation of the
blade, an air-cooling effect occurs, so that accumulation of heat
at the cutting edge can be reduced effectively.
As shown in FIGS. 1 and 2 diamond-layer recesses 2i are formed
on the outer circumferential edge of the steel base plate 1. The
recesses 2i each have a predetermined width (5 mm in the present
embodiment). The first blade portion 2a is disposed on both sides
of the recesses 2. Further, the second blade portions 2b separated
from the first blade portion 2a and serving as isolated cutting
elements, are disposed at predetermined positions of the steel base
plate 1.
The first blade portion 2a and the second blade portions 2b are
preferably attached to the steel base plate 1 by a so-called direct
sintering method in which formation of diamond-abrasive-grain layers
is performed simultaneously with bonding of the diamond-abrasive-grain
layers to the steel base plate 1.
The first blade portion 2a disposed along the outer circumferential
edge of the steel base plate 1 has recesses 2i which are formed
alternately on the front and reverse faces of the steel base plate
1. The recesses 2i facilitate intrusion of the diamond blade S into
a workpiece during cutting operation, and serve as discharge recesses
for discharging swarf and other substances. The recesses 2i incline
forward from the outer end thereof with respect to the rotation
direction of the steel base plate 1 whereby a substantially parallelogram-shaped
blade portion having an outer side longer than the inner side is
formed on either side of each of the recesses 2i. The first blade
portion 2a has a thickness slightly greater than that of the steel
base plate 1.
The shape of the first blade portion 2a formed along the outer
circumferential edge of the steel base plate 1 is not limited to
the above-described shape. For example, the recesses 2i may be omitted.
Further, a structure as shown in FIG. 3 may be employed. That is,
a plurality of slots 3 are formed in the outer circumferential portion
of the steel base plate 1 at constant intervals; and a diamond tip
is attached between two adjacent slots 3 as the first blade portion
2a.
The second blade portions 2b are formed on either the front or
reverse face of the steel base plate 1 or on both the front and
reverse faces of the steel base plate 1. For example, as shown in
FIG. 1 each of the second blade portions 2b has a substantially
trapezoidal shape which inclines forward from the outer end thereof
with respect to the rotation direction of the base plate, and is
formed on a line extending from the corresponding recess 2i of the
first blade portion 2a.
The second blade portions 2b are not limited to the above-described
shape and may assume any other shape such as a circular shape, a
triangular shape, or a polygonal shape.
The number of and interval between the second blade portions 2b
are properly determined in accordance with the size of the diamond
blade S, or the size of the isolated cutting elements 2b themselves.
A plurality of rows of the isolated cutting elements 2b may be disposed
from the center toward the outer cicumferential edge of the steel
base plate 1. Alternatively, each of the blade portions 2b may be
disposed at a different radial position. Further, the isolated cutting
elements 2b may be disposed only on the front or reverse face of
the steel base plate 1.
When the second blade portions 2b are formed on both the front
and reverse faces of the base plate, the second blade portions 2b
are formed on the front and reverse faces of the base plate with
a phase difference of a predetermined angle as measured with the
rotational center of the steel base plate 1 serving as a vertex.
Next, cutting work by use of the diamond blade S according to the
first embodiment will be described. First, the first blade portion
2a comes in contact with a workpiece (not shown) and starts cutting.
As the amount of intrusion of the diamond blade S into the workpiece
increases, the second blade portions 2b located closer to the center
of the steel base plate 1 come in contact with the workpiece. The
cutting work proceeds in this manner.
As described above, the workpiece is cut by the first blade portion
2a and the second blade portions 2b having different shapes, and
the flow of swarf is divided into a plurality of flows, due to the
presence of gaps between the first blade portion 2a and the second
blade portions 2b. Accordingly, swarf does not concentrate at the
neck, so that neck wear is prevented.
Moreover, since the second blade portions 2b grind the cut surfaces,
the finish of the cut surfaces can be improved.
In addition, when the diamond blade S of the present invention
is used, the workpiece is cut while the cut surfaces of the workpiece
are ground by the second blade portions 2b. Therefore, there can
be prevented generation of friction of steel center, which would
otherwise occur due to contact between the cut surface and the base
plate, so that lateral deflection of the diamond blade S during
cutting operation can be prevented. Thus, straight cutting is enabled.
Further, since the size of a clearance provided for suppressing
friction of steel center can be reduced, the diamond blade S can
be made thinner than can conventional diamond blades.
(Second Embodiment)
A diamond blade S according to the present embodiment is manufactured
by a so-called direct sintering method in which formation of diamond-abrasive-grain
layers is performed simultaneously with bonding of the diamond-abrasive-grain
layers to the steel plate. The diamond blade S comprises blade portions
2. In the diamond blade S according to the present embodiment, the
blade portions 2 include a first blade portion 2a disposed along
the outer circumferential edge of the steel base plate 1 second
blade portions 2b serving as isolated cutting elements separated
from the first blade portion 2a, and third blade portions 2c serving
as extended blade portions which extend toward the center of the
steel base plate 1.
When the diamond blade S is of 4-inch size, the diamond blade S
has an outer diameter of 107 mm, a blade thickness of 2.2 mm, and
a blade width of 8 mm, and the steel base plate 1 has an outer diameter
of 91 mm. These design values are changed in accordance with the
size of the diamond blade S. In the following description, the diamond
blade S is assumed to be of 4-inch size.
The steel base plate 1 is formed of carbon tool steel and has a
circular shape, and an attachment hole 1c for attachment to an unillustrated
jig is formed at the center of the steel base plate 1. On either
face of the steel base plate 1 are formed crest portions 1a having
an arcuate cross section and flat trough (recess) portions 1b which
form a wavy surface. The height of the crest portions is increased
gradually toward the outer circumference, and the width of the crest
portions is decreased gradually toward the center of the steel base
plate 1.
Further, the crest portions 1a and the trough (recess) portions
1b are curved to form a whirlpool-like shape such that they extend
radially toward the direction opposite the rotation direction of
the diamond blade S. The crest portions 1a and the trough (recess)
portions 1b are formed on both faces of the steel base plate 1 such
that their angular positions on the reverse face are shifted from
those on the front face.
The steel base plate 1 is preferably manufactured from a special
plate; e.g., a three-layer plate well known in the art. In this
case, cutting noise generated upon cutting stone or concrete material
can be lowered without any change in cutting performance.
Alternatively, a circular flat plate having neither the crest portions
1a nor the trough (recess) portions 1b may be used as the steel
base plate 1.
Diamond-layer recesses 2i are formed on the outer circumferential
edge of the steel base plate 1. The diamond-layer recesses 2i each
have a predetermined width (5 mm in the present embodiment). The
first blade portion 2a is disposed on both sides of each diamond-layer
recesses 2i.
As shown in FIGS. 5(b) and 5(c), the first blade portion 2a has
recesses 2i which are alternately formed on the front and reverse
faces of the steel base plate 1 such that the recesses 2i correspond
to the ends of the crest portions 1a and such that the recesses
2i are continuous with the trough (recess) portions 1b of the steel
base plate 1. The recesses 2i facilitate intrusion of the diamond
blade S into a workpiece during cutting operation, and serve as
discharge recesses for discharging swarf and other substances. The
recesses 2i incline forward from the outer end thereof with respect
to the rotation direction of the steel base plate 1 whereby substantially
parallelogram-shaped blade portions each having an outer side longer
than the inner side are formed on either side of each of the recesses
2i. Each of the second blade portions 2b has a substantially trapezoidal
shape which inclines forward from the outer end thereof with respect
to the rotation direction of the base plate, and is formed on a
line extending from the corresponding recess 2i of the first blade
portion 2a. The third blade portions 2c are formed to serve as extended
blade portions, each having a width substantially equal to that
of the crest portion of the steel base plate 1 and extending from
the diamond-layer joint portion 1d toward the center portion. The
first blade portion 2a, the second blade portions 2b, and the third
blade portions 2c each have a thickness slightly greater than that
of the steel base plate 1. Next, the arrangement of the blade portions
2 on the steel base plate 1 in the present embodiment will be described.
In the present embodiment, the third blade portions 2c are formed
at four equally spaced locations determined to correspond to the
positions of the crest portion 1a of the steel base plate 1 and
the second blades 2b are disposed at equal intervals to be located
between the third blade portions 2c.
Further, as shown in FIG. 4 (front view) and FIG. 6 (rear view),
when the second blade portions 2b and the third blade portions 2c
are provided on both the front and reverse faces of the steel base
plate 1 the second blade portions 2b and the third blade portions
2c are formed on the front and reverse faces of the base plate with
a phase difference of a predetermined angle as measured with the
rotational center of the steel base plate 1 serving as a vertex.
The number of and interval between the second blade portions 2b
and the number of and interval between the third blade portions
2c are properly determined in accordance with the size of the diamond
blade S and the sizes of the second and third blade portions themselves.
Next, cutting work by use of the diamond blade S according to the
second embodiment will be described. First, the first blade portion
2a comes in contact with a workpiece (not shown) and starts cutting.
As the amount of intrusion of the diamond blade S into the workpiece
increases, the second blade portions 2b located closer to the center
of the steel base plate 1 and the third blade portions 2c extending
toward the center side come in contact with the workpiece. The cutting
work proceeds in this manner.
As described above, the workpiece is cut by the first blade portion
2a, the second blade portions 2b, and the third blade portions 2c
having different shapes, and the gaps between the first blade portion
2a and the second blade portions 2b provide spaces immediately after
the recesses 2i of the first blade portion 2a in which no blade
portion is present. Accordingly, the flow of swarf is divided into
a plurality of flows, and thus swarf does not concentrate at the
neck, so that neck wear is prevented. Moreover, since the second
blade portions 2b and the third blade portions 2c grind the cut
surfaces, the finish of the cut surfaces can be improved.
When the diamond blade S of the present invention is used, neck
wear can be prevented as described above, and the wavy base plate
produces an air-cooling effect upon rotation, so that accumulation
of heat at the cutting edge is mitigated effectively. Further, the
following effect can be attained.
When the diamond blade S of the present invention is used, the
workpiece is cut while the cut surfaces of the workpiece are ground
by the second blade portions 2b and the third blade portions 2c.
Therefore, there can be prevented generation of friction of steel
center, which would otherwise occur due to contact between the cut
surface and the base plate, so that lateral deflection during of
the diamond blade S cutting operation can be prevented. Thus, straight
cutting is enabled. Further, since the size of a clearance provided
for suppressing friction of steel center can be reduced, the diamond
blade S can be made thinner than can conventional diamond blades.
In the above-described embodiment, an example in which the diamond
blade S has the second blade portions 2b is shown. However, the
second blade portions 2b may be omitted. Alternatively, there may
be employed a structure in which either the second blade portions
2b or the third blade portions 2c are formed on the front or reverse
face of the steel base plate 1.
(Third Embodiment)
A diamond blade S according to the present embodiment is manufactured
by a so-called direct sintering method in which formation of diamond-abrasive-grain
layers is performed simultaneously with bonding of the diamond-abrasive-grain
layers to the base plate. The diamond blade S comprises blade portions
2. In the diamond blade S according to the present embodiment, the
blade portions 2 include a first blade portion 2a disposed along
the outer circumferential edge of the steel base plate 1 second
blade portions 2b serving as isolated cutting elements separated
from the first blade portion 2a, and fourth blade portions 2d serving
as irregularly-shaped blade portions which extend toward the center
of the steel base plate 1.
When the diamond blade S is of 4-inch size, the diamond blade S
has an outer diameter of 105 mm, a blade thickness of 1.8 mm, and
a blade width of 6 mm, and the steel base plate 1 has an outer diameter
of 93 mm. These design values are changed in accordance with the
size of the diamond blade S. In the following description, the diamond
blade S is assumed to be of 4-inch size.
The steel base plate 1 is formed of carbon tool steel and has a
circular shape, and an attachment hole 1c for attachment to an unillustrated
jig is formed at the center of the steel base plate 1. The steel
base plate 1 is preferably manufactured from a special plate; e.g.,
a three-layer plate well known in the art. In this case, cutting
noise generated upon cutting stone or concrete material can be lowered
without any change in cutting performance.
Alternatively, in place of the above-described circular flat plate,
a circular plate which has crest portions 1a having an arcuate cross
section and flat trough (recess) portions 1b which form a wavy surface
may be used as the steel base plate 1.
Diamond-layer recesses 2i are formed on the outer circumferential
edge of the steel base plate 1. The diamond-layer recesses 2i each
have a predetermined width (5 mm in the present embodiment). Blade
portions 2a (or 2a and 2d) are disposed on both sides of each diamond-layer
recess 2i.
As shown in FIGS. 9(b) and 9(c), the first blade portion 2a has
recesses 2i which are alternately formed on the front and reverse
faces of the steel base plate 1. The recesses 2i facilitates intrusion
of the cutting edge into a workpiece during cutting operation, and
serve as discharge recesses for discharging swarf and other substances.
The recesses 2i incline forward from the outer end thereof with
respect to the rotation direction of the steel base plate 1 whereby
substantially parallelogram-shaped blade portions each having an
outer side longer than the inner side are formed on both sides of
each of the recesses 2i. Each of the second blade portions 2b has
a substantially trapezoidal shape which inclines forward from the
outer end thereof with respect to the rotation direction of the
base plate, and is formed on a line extending from the corresponding
recess 2i of the first blade portion 2a. The fourth blade portions
2d are formed to serve as irregularly-shaped blade portions of a
substantially squarish C-like shape which is formed through extension
of the adjacent parallelogram-shaped blade portions via the recess
2i toward the center side and through connection of inner ends of
the extended sections. The first blade portion 2a, the second blade
portions 2b, and the fourth blade portions 2d each have a thickness
slightly greater than that of the steel base plate 1.
Next, the arrangement of the blade portions on the steel base plate
in the present embodiment will be described. In the present embodiment,
the fourth blade portions 2d are disposed at four equally spaced
locations on the steel base plate 1 and the second blades 2b are
disposed at equal intervals to be located between the fourth blade
portions 2d.
Further, as shown in FIG. 8 (front view) and FIG. 10 (rear view),
when the second blade portions 2b and the fourth blade portions
2d are provided on both the front and reverse faces of the steel
base plate 1 the second blade portions 2b and the fourth blade
portions 2d are formed on the front and the reverse faces of the
base plate with a phase difference of a predetermined angle as measured
with the rotational center of the steel base plate 1 serving as
a vertex. The number of and interval between the second blade portions
2b and the number of and interval between the fourth blade portions
2d are properly determined in accordance with the size of the diamond
blade S and the sizes of the blade portions 2 themselves.
Next, cutting work by use of the diamond blade S according to the
third embodiment will be described. First, the first blade portion
2a comes in contact with a workpiece (not shown) and starts cutting.
As the amount of intrusion of the diamond blade S into the workpiece
increases, the second blade portions 2b located closer to the center
of the steel base plate 1 and the fourth blade portions 2d extending
toward the center side come in contact with the workpiece. The cutting
work proceeds in this manner.
As described above, the workpiece is cut by the first blade portion
2a, the second blade portions 2b, and the fourth blade portions
2d having different shapes, and the gaps between the first blade
portion 2a and the second blade portions 2b provide spaces immediately
after the recesses 2i of the first blade portion 2a in which no
blade portion is present. Accordingly, the flow of swarf is divided
into a plurality of flows, and thus swarf does not concentrate at
the neck, so that neck wear is prevented. Moreover, since the second
blade portions 2b and the fourth blade portions 2d grind the cut
surfaces, the finish of the cut surfaces can be improved.
When the diamond blade S of the present invention is used, neck
wear can be prevented as described above, and the following effect
can be achieved.
When the diamond blade S of the present invention is used, the
workpiece is cut while the cut surfaces of the workpiece are ground
by the second blade portions 2b and the fourth blade portions 2d.
Therefore, there can be prevented generation of friction of steel
center, which would otherwise occur due to contact between the cut
surface and the base plate, so that lateral deflection of the diamond
blade during cutting operation can be prevented. Thus, straight
cutting is enabled. Further, since the size of a clearance provided
for suppressing friction of steel center can be reduced, the diamond
blade S can be made thinner than can conventional diamond blades.
Further, since each of the fourth blade portions 2d has a generally
squarish C-like shape and has a recess at the center portion, during
cutting of the workpiece, swarf enters the center recess and is
discharged as the diamond blade rotates, and thus the amount of
swarf stagnating at the neck can be reduced. In this manner, neck
wear is prevented more reliably. In addition, the recesses reduce
the resistance generated on the side faces during cutting, so that
the diamond blade S has improved cutting efficiency.
In the above-described embodiment, an example in which the diamond
blade S has the second blade portions 2b is shown. However, the
second blade portions 2b may be omitted. Alternatively, there may
be employed a structure in which either the second blade portions
2b or the fourth blade portions 2d are formed on the front or reverse
face of the steel base plate 1.
(Fourth Embodiment)
As shown in FIG. 12 a diamond blade S according to the present
embodiment comprises a steel base plate 1 and a plurality of diamond
segments 2e. The diamond blade S is manufactured through direct
sintering in which the diamond segments 2e, which are structural
elements, are bonded to the steel base plate 1.
When the diamond blade S is of 4-inch size, the diamond blade S
has an outer diameter of 105 mm and eight diamond segments each
having a thickness of 1.8 mm and a width of 6 mm; and the steel
base plate 1 has an outer diameter of 93 mm and a thickness of 1.4
mm. These design values are changed in accordance with the size
of the diamond blade S. In the following description, the diamond
blade S is assumed to be of 4-inch size.
The steel base plate 1 is formed of carbon tool steel and has a
circular shape, and an attachment hole 1c for attachment to an unillustrated
jig is formed at the center of the steel base plate 1. The steel
base plate 1 is preferably manufactured from a special plate; e.g.,
a three-layer plate well known in the art. In this case, cutting
noise generated upon cutting stone or concrete material can be lowered
without any change in cutting performance.
A plurality of slots 3 are provided in the outer circumferential
portion of the steel base plate 1 at constant intervals. The slots
3 are formed to incline toward the rotation direction of the diamond
blade S. Diamond segment attachment portions 1a are formed between
adjacent slots 3 and the plurality of diamond segments 2e are disposed
at the diamond segment attachment portions 1a. In the present embodiment,
eight slots 3 are provided, and the diamond segment attachment portion
1a is formed at eight locations between the slots 3.
The steel base plate 1 is not limited to the above-described circular
plate, and may be a circular plate which has crest portions having
an arcuate cross section and flat trough (recess) portions which
form a wavy surface, or a circular plate which has alternately formed
crest portions and flat trough (recess) portions which extend radially
from the center. As to the slots 3 there is shown one having a
U-like shape. However, the slots 3 may have a key-like shape in
which the center side end is cut into a circular shape. Further,
the number of the slots 3 is not limited to 8 and may be changed
in accordance with the outer diameter of the diamond blade S.
Each of the diamond segments 2e has an extension portion 2g which
extends along the slot 3 located on the side of the front end portion
of the diamond segment 2e with respect to the rotation direction
of the diamond blade 5 and an elongated portion 2f which extends
along the outer circumferential surface of the diamond segment attachment
portion 1a to thereby form an L-like shape. Since the diamond segment
2e of the present embodiment is rounded at the bent portion of the
L shape, stagnation of swarf at the bent portion is prevented.
The extension portion 2g extends up to a point in the vicinity
of the bottom of the corresponding slot 3. The length of the extension
portion 2g is not limited to the length shown in FIG. 12 and may
be set freely insofar as the length is greater than the width of
the elongated portion 2f.
Further, each of the diamond segments 2e has a semicircular projection
2h which is formed in the vicinity of the rear end of the diamond
segments 2e with respect to the rotation direction and which extends
toward the attachment hole ic. Formation of the projection 2h enables
the diamond segment 2e to be fixed more reliably to the diamond
segment attachment portion 1a of the steel base plate 1.
In the present embodiment, each of the diamond segments 2e is formed
into a generally L-like shape whose bent portion is rounded; however,
the shape of the diamond segments 2e is not limited thereto. The
diamond segments 2e may be formed into a generally L-like shape
which has a sharp bent portion which is not rounded. Further, the
shape of the projections 2h is not limited to semi-circular, and
may be rectangular or triangular. Alternatively, there may be employed
a structure in which the projections 2h are omitted.
The diamond blade S of the present invention is manufactured by
a so-called direct sintering method in which the steel base plate
1 having been machined into a predetermined shape in advance and
a powder mixture of diamond abrasive grains and adhesive having
a predetermined composition are placed in a mold; and sintering
of the diamond segments 2e and bonding of the diamond segments 2e
to the steel base plate 1 are performed simultaneously in a hot
press sintering furnace. Needless to say, the diamond segments 2e
may be attached to the steel base plate 1 through brazing.
Next, cutting work by use of the diamond blade S according to the
present embodiment having the above-described structure will be
described. First, the elongated portions 2f of the diamond segments
2e come in contact with a workpiece (not shown) and start cutting.
As the amount of intrusion of the diamond blade S into the workpiece
increases, the extension portions 2g extending along the slots 3
come in contact with the workpiece. The cutting work proceeds in
this manner.
As described above, the workpiece is cut while its cut surfaces
are ground by the extension portions 2g. Further, swarf is discharged
from the slots 3. Therefore, it is possible to prevent swarf from
entering spaces located on the radially inner side of the joint
portion between the steel base plate 1 and the diamond segments
2e, to thereby prevent neck wear which would otherwise occur upon
swarf scraping the portion of the steel base plate 1 located on
the radially inner side of the joint portion. Moreover, the finish
of the cut surfaces can be improved.
In order to confirm the above-described neck-wear prevention effect,
the following experiment was performed. There were prepared a power
tool to which the diamond blade S of the present invention was attached
such that the diamond blade S could rotate in the forward direction,
and a power tool to which the diamond blade S of the present invention
was attached such that the diamond blade S could rotate in the reverse
direction. A mortar member and a grinding wheel were cut by use
each of the above-described tools, and the amount of neck wear was
measured.
Specifically, in the experiment, PDA-100D.multidot.12000 rpm (Product
of Hitachi Koki) was used as the power tool. As workpieces, a mortar
material and a grinding wheel (hardness: P) were used. In the case
of the mortar material, cutting over a length of 30 cm was repeated
100 times (total cut length: 30 m). In the case of the grinding
wheel, cutting over a length of 6 cm was repeated 130 times (total
cut length: 7.8 m).
The items evaluated in the neck wear measurement experiment were
amount (.DELTA.T) of wear of the diamond segments in the thickness
direction, and the amount (.DELTA.t) of wear of the steel base plate
in the thickness direction. The table of FIG. 17 shows the results
of the experiment.
The results of the experiment show that when a workpiece which
causes great wear of the diamond blade is cut, depending on the
angle of inclination of the extension portions 2g (the angle of
inclination of the slots 3), neck wear can be suppressed to about
60% through employment of the arrangement in which the extension
portions 2g of the diamond segments 2e are located on the front
side with respect to the rotation direction of the diamond blade
S, as compared with the arrangement in which the extension portions
2g of the diamond segments 2e are not located on the front side
with respect to the rotation direction of the diamond blade S.
Use of the diamond blade of the present invention prevents neck
wear as described above, and achieves the following effect.
That is, when the diamond blade S of the present invention is used,
the workpiece is cut while the cut surfaces of the workpiece are
ground by the extension portions 2g. Therefore, there can be prevented
generation of friction of steel center, which would otherwise occur
due to contact between the cut surface and the base plate, so that
lateral deflection of the diamond blade S during cutting operation
can be prevented. Further, since the size of a clearance provided
for suppressing friction of steel center can be reduced, the diamond
blade S can be made thinner than can conventional diamond blades.
Further, since the extension portions 2g are disposed along the
slots 3 swarf generated during cutting work is discharged via the
slots 3. Therefore, there can be prevented rotational friction which
is produced due to stagnation of swarf between the cut surfaces
and the steel base plate 1.
Moreover, since the slots 3 are formed to incline toward the rotation
direction, during cutting operation, the diamond segments 2e can
intrude into a workpiece more easily, and the stability of the diamond
blade S is maintained, so that the performance of the blade in traveling
straight can be improved.
Furthermore, since the diamond blade S of the present invention
is manufactured by the method in which sintering of the diamond
segments 2e is performed simultaneously with bonding of the diamond
segments 2e to the steel base plate 1 the diamond blade S can be
manufactured at low cost.
As shown in FIG. 16 the second blade portions 2b serving as isolated
cutting elements may be provided at predetermined positions separated
from the diamond segments 2e. When, as described above, the isolated
cutting elements are provided at predetermined positions of the
steel base plate 1 the flow of swarf is divided into a plurality
of flows due to the presence of gaps between the diamond segments
2e and the second blade portions 2b. Accordingly, swarf does not
concentrate at the neck, so that neck wear is prevented.
Moreover, since the second blade portions 2b grind the cut surfaces,
the finish of the cut surfaces can be improved.
In addition, when the diamond blade S of the present invention
is used, the workpiece is cut while the cut surfaces of the workpiece
are ground by the second blade portions 2b. Therefore, there can
be prevented generation of friction of steel center, which would
otherwise occur due to contact between the cut surface and the base
plate, so that lateral deflection during cutting operation can be
prevented. Thus, straight cutting is enabled. Further, since the
size of a clearance provided for suppressing friction of steel center
can be reduced, the diamond blade S can be made thinner than can
conventional diamond blades.
INDUSTRIAL APPLICABILITY
As described above, the present invention reduces neck wear of
a diamond blade to thereby improve the durability of the diamond
blade, which is greatly advantageous in terms of cost. Further,
since the diamond blade cuts a workpiece while its isolated cutting
elements or blade portions extending toward the center grind cut
surfaces of the workpiece, cut surfaces of excellent finish are
obtained.
In addition, since formation of diamond-abrasive-grain layers,
each of which has a complicated shape and serves as a blade portion,
and bonding of the diamond-abrasive-grain layers to the base plate
are performed through direct sintering, a diamond blade having excellent
performance can be provided at low cost.
Further, since slots are formed in the steel base plate, and extension
portions of diamond segments extend along the slots, rotational
friction stemming from friction of steel center and stagnation of
swarf is prevented, and surfaces of excellent finish can be obtained.
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