JPH06158612A - Circle cutting device for paved road surface and cutting edge used therefor - Google Patents

Abstract

PURPOSE:To make the cutting of circles having different diameters possible without transmitting vibration occurring during working process to other parts by vertically providing a driving main shaft from an upper side, and protruding a cutting edge arm whose length is variable. CONSTITUTION:A rear cover 116 is opened to open the rear part of the load carrying platform of a vehicle. Next a cutting device 10 is fixed to a supporting face composed of the rear cover 116 and the rear end of the load carrying platform. The length of an arm 13 and a cutting edge 14 are properly selected. A handle 18a is rotatingly operated to move a supporting base 15 so as to position a plumb 38 at the center of a circle to be cut. A handle 27 is rotated to lower a diamond tip 42 at the lower end of the cutting edge 14 to a position where the tip 42 comes into contact with a road face. The arm 13 is rotated centering around the center P of the circle to move the cutting edge 14 along its circumference for circularly push-cutting the road face by the diamond tip 42. Thus since a support is not erected on the road face, vibration occurring during a work process is not transmitted to other parts, and the road face can be cut into an optional diametral shape by regulating the arm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paved road surface circular cutting device for cutting a periphery of a paved road surface occupant such as a manhole into a circle, and a cutting blade used for the cutting device. While making it easy,
It occupies a small area on the road surface and is easy to install at a predetermined position.
In addition, the structure is simple and can be provided at extremely low cost as compared with the conventional device.

[0002]

2. Description of the Related Art Conventionally, the following three types of devices have been proposed as this type of circular cutting device. First, as shown in FIG. 10, a column 3 is erected on the central position of the lid 1 of the manhole, an arm 4 is projected from the upper end of the column 3, and a drive unit is provided at the tip of the arm 4. The circular cutting blade 5 is attached via 6, and the drive unit 6 rotates the arm 4 with the support post 3 as a fulcrum and also rotates the disc-shaped cutting blade 5 in the vertical direction indicated by the arrow in the figure. It revolves while revolving itself and cuts the road surface R into a circle C as shown by the dotted line. (JP-A-63-27519, JP-A-63-55204)

Second, as shown in FIGS. 11 (A) and 11 (B), a pillar 3 is erected on the central upper surface of the manhole cover 1 or on a reinforcing member, and a sleeve 7 is slidably mounted on the pillar 3. The cylindrical cutting blade 5 having the blade portion 5a provided on the lower end periphery is fixed to the lower end of the sleeve 7, and the cutting blade rotation motor 8 is attached.
Is mounted and the sleeve 7 is lowered by the cylinder 9 while rotating the cutting blade 5 to cut the paved road surface into a circular shape. (JP-A-59-141611)

Third, as shown in FIG. 12, a pillar 3 is erected on the road surface R, a first arm 4A rotated by a first motor 8A is projected from the pillar 3, and the first arm 4A is projected. 4A
The second arm 4B is attached to the tip of the robot so that it can be moved up and down by the second motor 8B, and the third motor 8C is attached to the second arm 4B.
The third arm 4C which is rotated in the horizontal direction by is attached, and the blade 5 is attached to the lower end of the third arm 4C. In the device, the cutting blade 5 is driven by the second motor 4B.
While lowering, the cutting blade 5 is horizontally rotated by the third motor and is revolved along the circular cutting line by the first motor 4A, thereby cutting the pavement road surface into the circle C. (JP-A 61-277704)

[0005]

In all of the above-mentioned three types of conventionally proposed cutting devices, the columns are erected on the road surface at the center position of the circular cutting part or on the manhole cover or supporting member. However, it requires a mechanism for holding the column, and it takes time to position the column at a predetermined position. Further, when cutting a small circle, there is a problem that the column holding mechanism becomes larger. Furthermore, if the support column is installed on the top surface of the manhole cover or on other supporting members, vibration and load of the driving unit are applied during cutting work, which easily damages the lid or supporting members and causes a large noise during work. Occurs. Moreover, the shoulders around the manhole cover loosened due to vibration,
There was a problem that earth and sand and Alfalto fragments fell below the manhole.

[0006] Usually, the size of the manhole cover is
There are various diameters of 75, 100, 125, 150, 180, 200 cm, and it is necessary to change the circular area to be cut accordingly. Therefore, when using the cylindrical cutting blade as shown in the second type, it is necessary to prepare cylindrical cutting blades having various diameters. Moreover, since the cylindrical cutting blade bends a flat plate to form a cylindrical member, it is difficult to obtain circularity, and it is difficult to manufacture a blade having a large diameter.

Further, when the above-mentioned disc-shaped cutting blade of the first type is rotated in the vertical direction, it is necessary to reduce the diameter of the disc-shaped cutting blade in order to cut a circle having a small diameter. In this case, the strength of the cutting blade becomes a problem. Therefore, it is difficult to cut a small-diameter circle with the first type.

Further, in the above-mentioned third type, the structure such as three motors for revolving and rotating while lowering the cutting blade is extremely complicated, and therefore the weight of the entire apparatus becomes large. Therefore, this large weight is applied to the supporting column supporting member such as the manhole cover, and there is a problem that the cutting device becomes expensive.

As described above, any of the conventionally proposed circular cutting devices has a problem, and in particular, since the columns are erected on the road surface and there are many members other than the columns that occupy the road surface, There is a problem that the area occupied by the road surface tends to be large, which tends to obstruct traffic when cutting the road surface.

SUMMARY OF THE INVENTION The present invention is intended to solve various problems of the above-mentioned conventionally proposed device, and to prevent the pillar arranged at the central position of the circular cutting portion from standing on the road surface and to cut the cutting device. Provided is a pavement road surface circular cutting device which can occupy as little as possible on a road surface, can cut a circle of various diameters from a small diameter to a large diameter, and can be provided at a low cost, and a cutting blade used for the cutting device. It is something to do.

[0011]

SUMMARY OF THE INVENTION That is, according to the present invention, a sleeve is externally fitted to a pillar arranged laterally of a road surface circular cut portion so as to be able to move up and down, and a rotary drive means such as a prime mover is mounted on the sleeve. At the same time, a drive main shaft that is rotationally driven by the prime mover is rotatably mounted, and the axis of the drive main shaft is arranged above the center point of the road surface circular cut portion on the same line as above, while projecting radially at the lower end of the drive main shaft. While fixing one end of the arm, the cutting blade is fixed to the other end of the arm, the cutting tip is fixed to the lower end edge of the cutting blade, and the drive spindle is rotated while descending to cut through the arm. Provided is a pavement road surface circular cutting device configured to move a blade along a circumference.

Further, according to the present invention, the arm is attached to the tip of the arm rotated by the drive means and is moved along the circumferential direction of the cutting circular portion so as to be perpendicular to the paved road surface. Removably fixed to the tip,
A cutting blade for use in a paved road surface circular cutting device having a diamond tip at its lower end edge.

The cutting blade has an arc-shaped horizontal section, and the curvature of the arc is set to have the same curvature as the cutting circle. When the length of the cutting blade in the circumferential direction is short and the cutting circle has a large diameter, the cutting blade can be formed of a flat plate with a horizontal cross section being a straight line.

The columns of the cutting device are composed of a pair of columns erected from a support stand fixed on the vehicle carrying the cutting device via positioning means, and the sleeves are slidably fitted on these columns. At the same time, the sleeve is configured to move up and down by rotating a feed screw, the prime mover and the transmission are mounted on a frame protruding from the sleeve, and the upper portion of the drive spindle arranged in the vertical direction is rotatable. I support you. Although it is preferable to use the cutting device fixed to the transportation vehicle even during work, it is not always necessary to use it while it is mounted on the vehicle, and it is installed on the base etc. which is arranged on the side of the circular cutting part. May be.

The positioning means of the cutting device moves the support stand on which the pillars are erected in the front-rear direction and the left-right direction of the vehicle so that the swinging down from the lower end of the drive spindle coincides with the center of the cutting circular portion. It is configured to let.

The arm projecting radially from the lower end of the drive spindle is composed of one arm or a plurality of arms protruding at equal intervals. These arms are provided with a cooling water passage from the drive spindle side, and a cutting blade from the arm tip. It is configured to inject cooling water toward. The cooling water passage may be formed by providing a hollow portion in the arm, or a pipe may be attached along the arm to use the pipe as the cooling passage. Further, each arm is divided into two members, and these members are slidably connected to each other so that the length of the arms can be adjusted so that different diameters of the cut circle can be accommodated.

[0017]

In the paved road surface circular cutting device of the present invention, the drive spindle is rotated by the prime mover while being lowered, and the arm projecting from the drive spindle rotates about the drive spindle as a center of rotation, and the cutting blade fixed to the arm tip is The cutting surface is moved along the outer circumference of the cutting circle, and the road surface is cut into a circle by the cutting tip attached to the lower end of the cutting blade.

At the time of the above cutting work, the road surface is so-called pushed by the cutting tip, but since the diamond tip of superhardness is used as the cutting tip, the paved road surface can be cut smoothly.

When the diameter of the circular shape to be cut is changed, it can be dealt with by adjusting the length of the arm and changing the cutting blade attached to the tip of the arm. still,
When the cutting blade is short in the circumferential direction and has no curvature, it is not necessary to replace the cutting blade. That is, it is possible to cut circles having different diameters without replacing the constituent members of the cutting device.

During the cutting work by this device, the pillar which was conventionally installed at the center position of the circular cutting portion is eliminated, the drive spindle is positioned above the center position, and the drive spindle is easily positioned at the center position. Since this is possible, it is possible to solve the conventional problem that occurs when the support is erected from the center of the circular cutting portion during the cutting work.

[0021]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. 1 to 7 show a first embodiment, a paved road surface circular cutting device 10 is a loading platform 1 for a vehicle 11 such as a truck.
1a is transported to the working position, and at the working position, the rear lid 11b of the vehicle 11 is opened, the rear lid 11b is held horizontally with the loading platform 11a, and the vehicle horizontal portion is used as a cutting device supporting surface. is doing. As shown in FIG. 1, the cutting device 10 is mounted on a vehicle 11, and vertically extends a drive spindle 12 positioned at the center P of a circular cut portion of a road surface R from above and projects an arm 13 from the drive spindle 12. The cutting blade 14 attached to the tip of the arm 13 makes an annular cut C on the road surface R.

The cutting device 10 is supported on the cutting device supporting surface of the vehicle 11 through positioning means for adjusting the entire position of the drive main shaft 12 to the center P of the cutting portion in the longitudinal and lateral directions. The rotation drive means is attached to the vertical movement means standing upright from the positioning means, and the drive main shaft 12 and the arm 1 are attached by the rotation drive means.
3 and the cutting means including the cutting blade 14 are driven.

The respective means of the cutting device 10 will be described in detail below.
First, the positioning means is the flat plate-shaped support base 15 of the cutting device 10.
Is the front-rear direction X (vehicle length direction) and the left-right direction Y (vehicle width direction)
(Shown in Figure 2). That is, the fixing pins 16 are attached to the rear portion of the luggage carrier 11a on the vehicle supporting surface and the rear lid 11b.
While projecting a and 16b, insertion holes for inserting the fixing pins 16a and 16b are formed in the pair of left and right front and rear frames 17 at the lower end of the cutting device 10, and the fixing pins 16 are inserted into these insertion holes.
The cutting device 10 is fixed to the vehicle support surface by inserting a and 16b.

As shown in FIG. 2, the front and rear frames 17 include
A screw shaft 18 in the front-rear direction is rotatably and immovably mounted via a bearing, and a handle 18 at the tip of one screw shaft 18 is attached.
A is attached and the left and right screw shafts 18 are transmitted. A front and rear moving frame 19 having a female screw hole to be screwed with the screw shaft 18 is provided, and a left and right screw shaft 20 is rotatably and immovably mounted on the upper surfaces of the pair of left and right front and rear moving frames 19 via bearings 19b. I am hanging. A handle 20a is attached to the tip of the screw shaft 20, and a left and right moving frame 21 having a screw hole to be screwed into the screw shaft 20 is provided, and the left and right moving frame 21 is fixed to the lower surface of the support base 15. In this way, the support base 15 is moved in the front-rear direction by rotating the handle 18a of the screw shaft 18 and the handle 2 of the screw shaft 20 is moved.
0a is rotated to move in the left-right direction.

As shown in FIG. 3, the vertical moving means for lowering the cutting blade 14 of the cutting device 10 during the cutting operation is as follows.
On the upper surface of the support base 15, the lower ends of the two main columns 22 are attached to the main bearing 2.
The main pillars 22 are fixedly supported by 3 and juxtaposed upward, and the upper ends of these two main pillars 22 are connected by a connecting plate 24, and the intermediate portions are connected by a sleeve 25. The connecting plate 24
Further, the sleeve 25 is provided with screw holes 24a, 25a, and the feed screw 26 is penetrated through the screw holes 24a, 25a to be vertically attached. The large diameter upper portion 26a of the feed screw 26 is locked and held on the upper surface of the connecting plate 24, and a handle 27 is attached to the upper end. Lead screw 2
Reference numeral 6 loosely inserts the inside of the screw hole 24a, is screwed into the screw hole 25a, and rotates the handle 27 to move the sleeve 25 up and down.

The sleeve 25 has cylindrical portions 25b on both sides.
Is slidably fitted on the column 22, and the cylindrical portions 25b on both sides are
It has a shape having a central portion 25c having the screw hole 25a between them, and the rotation driving means is connected to the central portion 25c. That is, as shown in FIG. 4, a drive portion mounting frame portion 25d is provided on the front surface side of the central portion 25c, while a bearing portion 25e for rotatably supporting the drive spindle 12 is provided on the rear surface side thereof.

The rotation driving means is provided with a prime mover 30, a transmission 31 connected to the output shaft of the prime mover 30, and a V pulley 32 attached to the output shaft of the drive 31 in the drive unit mounting frame portion 25d. . On the other hand, the bearing 25e on the opposite side rotatably supports the upper end of the drive main shaft 12 and vertically attaches the drive main shaft 12 to the drive main shaft 12.
A pulley 33 is installed corresponding to the V pulley 32, and a V belt 34 is wound around the V pulleys 32 and 33. In the figure, 35 is a pulley cover. A prime mover switch (not shown) is provided on the drive unit mounting frame 25d side. When the prime mover switch is turned on to drive the prime mover 30, the drive spindle 12 is indicated by an arrow in the figure via the transmission 31 and the V belt 34. I am trying to rotate it.

As shown in FIG. 5, the drive main shaft 12 is a hollow shaft, and the cooling water is allowed to flow through the hollow hole from the upper end opening to the lower end opening. Drive spindle 12
An arm 13 is detachably fixed to the lower end of the arm 1.
3 is also a hollow shaft, and the hollow hole of the arm 13 is used as the drive main shaft 12
The cooling water supply passage is made to communicate with the hollow hole.

Specifically, a vertical coupling 13a is provided at one end of the arm 13, and the lower end of the drive main shaft 12 is inserted into the coupling 13a and fixed by a bolt 36. From the lower end of the coupling 13a, a cutting blade mounting portion 13b is provided which is inclined downward toward the outside and protrudes, and the tip thereof is bent vertically downward.

Coupling 1 coaxial with the drive main shaft 12
At the center of the bottom surface of 3a, a hook 37 is provided so as to project downward, and a hook 38 is attached to the hook 37. The plumb bob 38 moves the cutting device 10 in the front-rear direction and the left-right direction by the positioning means so as to be positioned above the cutting center point P, and thus the drive spindle 12 is centered at the center point P. .

As shown in the figure, the arm 13 is divided into a base member 13-1 on the side where the coupling 13a is provided and a tip member 13-2 on the side where the cutting blade mounting portion 13b is provided. 13-1 and 13-2 are slidably fitted and connected and fixed by screws or the like (not shown) at required positions. By adjusting the length L of the arm 13 in this way, the diameter of the circular shape to be cut can be adjusted.

Member 13-1 slidably connected
And 13-2 are provided with cooling water passages as hollow shafts as described above, and cooling water passages 13g are also provided in the cutting blade mounting portion 13b protruding vertically downward of the tip side member 13-2. The lower end of the passage 13g is bent to form an injection port 13h outward.

As shown in FIG. 6, the cutting blade mounting portion 13b is provided.
Has a wide lower end, bolt holes 13i are provided on both sides thereof, and the cutting blade 14 is detachably attached by a bolt 39. The cutting blade 14 is attached vertically downward from the lower portion of the cutting blade attachment portion 13b so that the tip thereof abuts the road surface. The cutting blade 14 has an arc shape whose horizontal cross section has a required curvature, and the curvature is defined by the center P of the cutting portion.
The same as the curvature of the cutting circle drawn with the center as. In the cutting blade 14 of the embodiment, its circumferential length is approximately 1/20 of the entire circumference of the cutting portion. Note that the length of the cutting blade 14 in the circumferential direction is not limited, and may be a very short straight line shape. Further, the length of the cutting blade is also set in relation to the number of arms protruding from the drive spindle.

Diamond tips 42 are fixed to the lower edge of the cutting blade 14 by brazing at predetermined intervals.
Although the five diamond tips 42 are fixed in this embodiment, the number of the diamond tips 42 installed can be changed depending on the length of the cutting blade 14.

Next, an operation process of the paved road surface circular cutting device having the above structure will be described. First, as shown in FIG.
1 is stopped near the lid 1 of the manhole, and then the rear lid 11
b is opened to open the rear portion of the loading platform, and the cutting device is fixed to the support surface including the rear lid 11b and the rear end of the loading platform.

The length L of the arm 13 of the cutting device 10 and the cutting blade 14 attached to the tip of the arm 13 are set in advance so as to correspond to the cutting circle corresponding to the diameter of the lid 1 of the manhole. The length L of the arm 13 may be adjusted and then the required cutting blade 14 may be selected and attached.

Next, the plumb bob 38 is attached to the hook 37, and the handles 18a and 20a of the positioning means are rotated to move the support 15 so that the plumb bob 38 is located above the center of the cutting circle. At the same time, the handle 27 of the feed screw 26 for vertical movement is rotated to descend to the position where the diamond tip 42 at the lower end of the cutting blade 14 contacts the road surface.

After the above centering is completed, the prime mover 3
Start 0. At this time, a switch for safety measures of the transmission 31 is turned off in advance, and the power from the prime mover 30 is transmitted to the V pulley 32, the V belt 34,
The drive pulley 12 is prevented from being transmitted through the V pulley 33.

Next, as shown in FIG. 7, the transmission 3
1 is turned on to rotate the drive spindle 12 in the horizontal direction. The rotation of the drive spindle 12 causes the arm 13 to rotate about the circular center point P as a fulcrum, the cutting blade 14 to move along the circumference, and the diamond tip 42 at the lower end pushes the road surface into a circular shape.

Thereafter, the handle 27 is rotated to rotate the cutting blade 1.
4 while lowering the cutting blade 14 by the prime mover 30.
Move along the circumference to cut and cut the paved road surface. The cutting blade 14 is moved a required number of times along the entire circumference in accordance with the cutting depth to perform annular cutting with a predetermined depth.

At the time of the cutting operation, cooling water is supplied to the cooling water passage at the upper end opening of the drive spindle 12, and is cooled from the tip of the arm toward the cutting blade 14 through the cooling water passage formed by the hollow holes of the drive spindle 12 and the arm 13. Spray water. This jet of cooling water reduces heat generation and wear of the diamond tip 42 and the cutting blade 14.

The pavement road surface circular cutting device of the present invention is not limited to the above-mentioned structure. For example, as shown in FIG. 8 and FIG.
Two arms 13 ', 13 "projecting from the lower end of the drive spindle 12 in the diameter direction may be provided, and the cutting blades 14 may be attached to the tips of these two arms. The number of arms to be projected is not limited, but it is preferable to increase the number of arms as the diameter of the cut circle increases.

Further, a depth meter may be provided on the drive main shaft 12 or the main pillar 22 so that the cutting depth of the road surface can be seen at a glance. Further, the circumferential length of the cutting blade 14 curved in an arc shape is set to 1/20 of the circumference of the cutting circle, but the length in the circumferential direction is not limited, and the cutting circle is If the curvature is the same, and if the length in the circumferential direction is extremely short, it may be straight instead of arcuate. In that case, it is not necessary to replace the cutting blade according to the diameter of the cutting circle. Can be Further, although the transmission of the driving means uses the V pulley and the V belt, the main shaft may be rotated by using a transmission device such as a gear. Furthermore, although the vertical movement means rotates the handle to raise and lower the sleeve via the feed screw, a prime mover such as a motor may be used. In addition, in the present embodiment, the workability is improved by installing it on the vehicle 11, but it goes without saying that a transportation table or the like may be used.

[0044]

As is clear from the above description, in the paved road surface circular cutting device of the present invention, the driving main shaft is arranged above instead of standing up the support pillar on the road surface at the center position of the cutting circle. Therefore, it is possible to prevent the support surface from being damaged due to the vibration and the load applied to the upright columns as in the conventional case. Further, it is not necessary to install a member for holding the support on the road surface, and the area occupied by the road surface can be reduced. Moreover, if the cutting operation is carried out with the entire cutting device mounted on the transport vehicle, the installation of the cutting device is easy and
From this point as well, the area occupied by the road surface can be reduced.

Further, since the ultra-hard diamond tip is used as the road surface cutting tip, it is possible to push down the road surface so to speak while lowering the diamond tip. Accordingly, the drive mechanism can be simplified because the cutting blade needs only to revolve along the circumference of the cutting circle. Further, since the cutting blade is lowered by rotating the screw shaft by rotating the handle to lower the sleeve to be screwed, only one motor is required to revolve the cutting blade. The structure can be made extremely simple as compared with the conventional structure, and the price can be reduced, the weight can be reduced, and the size can be reduced.

Further, since the cutting blade has an arc shape rather than a cylindrical shape, it can be easily manufactured even for cutting a large diameter. Moreover, it is possible to easily prepare cutting blades having various diameters from a small diameter to a large diameter. Also,
Since the length of the arm is adjustable, the length can be adjusted facing the diameter of the circular shape to be cut, and various types of circular shapes can be cut by replacing the cutting blade attached to the tip of the arm. It has various advantages such as.

[Brief description of drawings]

FIG. 1 is a front view showing a state in which a paving road surface circular cutting device according to a first embodiment of the present invention is mounted on a vehicle to perform a cutting operation.

FIG. 2 is a schematic plan view showing a positioning means of the cutting device.

FIG. 3 is a side view of the cutting device.

FIG. 4 is an enlarged front view of a main part of a drive unit of the cutting device.

FIG. 5 is an enlarged front view of an essential part of a cutting means of the cutting device.

FIG. 6 is a bottom view showing a state in which a diamond tip is attached to the cutting blade.

FIG. 7 is a schematic view showing a cutting operation by the cutting device.

FIG. 8 is a schematic view similar to FIG. 7, showing another embodiment of the present invention.

9 is a front view of a main portion of the embodiment of FIG.

FIG. 10 is a perspective view of a conventional road surface circular cutting device.

FIG. 11 (A) is a front view of another conventional road surface circular cutting device, and FIG. 11 (B) is a perspective view of a cutting blade used in the cutting device.

FIG. 12 is a front view of another conventional road surface circular cutting device.

[Explanation of symbols]

 10 Cutting Device 11 Vehicle 12 Drive Spindle 13 Arm 14 Cutting Blade 22 Strut 24 Sleeve 26 Feed Screw Shaft 30 Motor 42 Diamond Tip

Claims (4)

[Claims] 1. A drive main shaft, which is externally fitted with a sleeve vertically movable on a pillar arranged on the side of a circular cut portion of a road surface, and in which the rotary drive means such as a prime mover is mounted and which is rotationally driven by the prime mover. Is rotatably mounted and the axis of the drive spindle is arranged above the center of the circular cut surface of the road, while one end of the arm protruding radially is fixed to the lower end of the drive spindle. A cutting blade is fixed to the other end of the cutting blade, a cutting tip is fixed to the lower end edge of the cutting blade, the sleeve is lowered to lower the drive spindle, and the engine is rotated to move the cutting blade through the arm. Circular cutting device for paved road surface, which is configured to move along the circumference of the cutting circle. 2. The column is fixed to a vehicle for transporting a cutting device through positioning means, and the positioning means adjusts the drive spindle so as to be located above the center of the circular cutting portion. Item 1. A pavement road circular cutting device according to Item 1. 3. A cutting blade attached to the tip of an arm rotated by a drive means and moved along the circumferential direction of a cutting circle, which is attached to and detached from the arm tip so as to be perpendicular to the paved road surface. Freely fixed, equipped with a diamond tip on the lower end edge, and used for a paving road surface circular cutting device characterized in that the road surface is cut by pushing the road surface with the diamond tip according to the rotation and lowering of the arm. blade. 4. The horizontal cross section is arcuate, the curvature of which is the same as the curvature of the cutting circle, and the diamond tips are fixed at predetermined intervals along the lower edge of the arcuate shape. The cutting blade according to claim 3.