Stone working – Sawing – Rotary
Reexamination Certificate
2000-07-11
2002-06-11
Eley, Timothy V. (Department: 3723)
Stone working
Sawing
Rotary
C451S547000
Reexamination Certificate
active
06401705
ABSTRACT:
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)
72
A 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 ele
Eley Timothy V.
Lorusso & Loud
Nguyen Dung Van
Sankyo Diamond Industrial Co., Ltd.
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