Disk-shaped rotary tool

Abstract

A disk-shaped rotary tool (1) has a plurality of slits (10) provided on a disk-shaped base metal (2). The plurality of slits (10) include a plurality of first slits (11) that are long in the circumferential direction in a first annular region (13) of the base metal (2), are arranged in the circumferential direction, and do not overlap each other in the radial direction. The plurality of slits (10) include a plurality of second slits (12) disposed in a second annular region (14) so as to overlap or touch arcuate end portions (11b, 11c) of the plurality of first slits (11) in the radial direction. At least one of the slits (10) is present in the entire length in the circumferential direction of the base metal (2).

Description

Disc-shaped rotary tool

[0001] The present disclosure relates to a disk-shaped rotary tool used for processing, for example, wood, wood-based materials, synthetic resin materials, steel materials, non-ferrous metals, and the like.

[0002] Conventionally, a circular saw blade with multiple cutting edges arranged along the outer periphery of a disk-shaped base metal has been proposed as a disk-shaped rotary tool of this type. JP 4136893B describes a circular saw blade with multiple slits formed in the base metal, each shaped like a long, thin hole. By providing the slits, the vibration-damping properties of the base metal can be improved and the critical rotation speed of the circular saw blade can be increased. By increasing the vibration-damping properties of the base metal, the generation of vibrations that adversely affect the quality of the cut surface can be suppressed. Furthermore, noise generated when cutting a workpiece can be suppressed. By increasing the critical rotation speed of the circular saw blade, i.e., the rotation speed at which the circular saw blade buckles, the circular saw blade can be used at a high rotation speed even if its thickness is reduced. Furthermore, vibration-damping properties can be improved by, for example, filling the slits with resin.

[0003] As described in JP 4136893B, the slits provided in conventional circular saw blades are, for example, S-shaped. The slits extend generally in the circumferential direction, but include portions that are inclined relative to the circumferential direction. Multiple slits are provided in a line in the circumferential direction. The end of a slit on the front side in the rotational direction of the circular saw blade is generally aligned radially with the end of an adjacent slit on the rear side in the rotational direction. Increasing the number of slits improves the critical rotation speed.

[0004] In the case of conventional slits, increasing the number of slits shortens the distance between them, which limits the number of slits that can be provided, and therefore limits the improvement of the critical rotation speed of the circular saw blade.

[0005] In the conventional slit shape described in JP4136893B, the centrifugal force during rotation stretches the base metal radially outward, creating gaps in the slit, which can lead to chip clogging, especially in areas that are inclined relative to the circumferential direction. If used while the base metal is clogged with chips, it can bend. Chip clogging can be suppressed to some extent by filling the slit with resin. However, if the chips are harder than the resin, such as aluminum powder, the chips may scrape the resin at the inclined portion of the slit and enter the slit. This makes it difficult to sufficiently suppress chip clogging. Therefore, there is room for improvement in suppressing chip clogging.

[0006] With conventional slits, tensile stress caused by centrifugal force during rotation could cause cracks to form in the base metal from the ends of the slits. Because the ends of adjacent slits are aligned radially and close to each other, cracks tend to form in the area between the ends. Therefore, there was room for improvement to suppress cracks in the base metal.

[0007] The present disclosure was completed in consideration of the above-mentioned circumstances, and an object of the present disclosure is to provide a disk-shaped rotating tool that can increase the critical rotation speed while suppressing chip clogging and cracking in the slit portion.

[0008] According to one aspect of the present disclosure, a disk-shaped rotary tool has a plurality of slits provided in a disk-shaped base metal. The plurality of slits includes a plurality of first slits that are circumferentially long and aligned in the circumferential direction within a first annular region of the base metal and do not radially overlap one another. The plurality of slits also includes a plurality of other slits that are arranged in other annular regions so as to radially overlap or contact each end of the plurality of first slits. At least one of the slits is present throughout the entire circumferential length of the base metal.

[0009] The first annular region is located, for example, between two concentric circles centered on the base center of the base. The other annular region is located radially outside or inside the first annular region, for example, between two concentric circles centered on the base center. The other slits located in the other annular region are positioned in cooperation with the first slit so that there is at least one slit along the entire circumferential length of the base.

[0010] Therefore, a plurality of first slits are arranged in the first annular region, and a plurality of other slits are arranged in the other annular regions. This allows a larger number of slits to be provided in the base metal. As a result, the base metal is more likely to expand radially outward when rotated and centrifugal force is applied thereto. As a result, the easier it is for the base metal to expand radially outward, the higher the critical rotation speed of the disc-shaped rotating tool can be. Furthermore, by providing a plurality of other annular regions each having slits, the base metal is even more likely to expand radially outward. As a result, the base metal can be subjected to a greater centrifugal force. This allows a higher critical rotation speed of the disc-shaped rotating tool.

[0011] According to another feature of the present disclosure, the base metal has two to four layers of radially arranged annular regions, each having a plurality of slits. For example, the base metal may have a second annular region radially outward of the first annular region, and the second annular region may have a plurality of second slits that are circumferentially long and aligned in the circumferential direction and do not overlap with each other in the radial direction. The base metal may have a third annular region radially outward of the second annular region, and the third annular region may have a plurality of third slits that are circumferentially long and aligned in the circumferential direction and do not overlap with each other in the radial direction. The first slits, the second slits, and the third slits are arranged so that there is at least one slit along the entire circumferential length of the base metal.

[0012] Therefore, two to four layers of annular regions with multiple slits aligned in the circumferential direction can be stacked radially. This allows the base metal to easily expand radially outward. Furthermore, by not stacking five or more layers, the rigidity of the base metal against axial stress can be ensured. Thus, the critical rotation speed of the disk-shaped rotating tool can be increased while maintaining the rigidity of the base metal.

[0013] According to another feature of the present disclosure, the plurality of first slits each have a slit body on and along the same first imaginary circle. The plurality of other slits each have a slit body on and along the same other imaginary circle. The first imaginary circle is, for example, a circle centered on the base metal center. The other imaginary circle is, for example, a circle located radially outward from the first imaginary circle and centered on the base metal center. The line width of the imaginary circle is, for example, 1 mm, 3 mm, or 5 mm.

[0014] Therefore, the slit bodies of the multiple first slits are arranged on a first imaginary circle, and the slit bodies of the multiple other slits are arranged on other imaginary circles. This allows the radial width of the annular region in which the multiple first slits and multiple other slits are provided to be shortened. Therefore, multiple annular regions can be efficiently overlapped in the radial direction even in a narrow region. This allows the number of slits provided in the base metal to be increased, making it easier for the base metal to expand radially outward. This allows the critical rotation speed of the disc-shaped rotating tool to be increased.

[0015] Furthermore, the slit body is not inclined relative to the circumferential direction. Through extensive research, it has been discovered that chips tend to get stuck in the inclined portion of the slit, which includes components extending in the radial direction. This prevents chips from clogging the slit body. This also prevents chip clogging from causing distortion in the base metal that is harmful to cutting.

[0016] According to another feature of the present disclosure, both ends of each of the plurality of other slits in the circumferential direction radially overlap with the corresponding first slit at an angle of 1 / 3 to 1 / 1 of the central angle of the corresponding first slit. By setting the angle within this range, the critical rotation speed of the disk-shaped rotating tool can be sufficiently increased.

[0017] According to another feature of the present disclosure, the plurality of first slits and the plurality of other slits each have a slit body with a width of 2.0 mm or less and an arc-shaped end portion with a diameter greater than the width of the slit body. By providing the arc-shaped end portion at the end of the slit, stress concentration at the end of the slit can be suppressed. This can prevent cracks from occurring at the end of the slit, which is particularly prone to cracking. Furthermore, by providing the slit with a width that allows resin to be filled, the vibration damping of the disk-shaped rotary tool can be improved.

[0018] According to another feature of the present disclosure, the plurality of first slits and the plurality of other slits each have a slit body with a width of 1.0 mm to 10.0 mm and an arc-shaped end portion with a diameter substantially equal to the width of the slit body. By providing the arc-shaped end portion at the end of the slit, stress concentration at the end of the slit can be suppressed, thereby suppressing the occurrence of cracks. Furthermore, by forming the slit as a through hole with a width sufficient for chips to pass through without filling it with resin or the like, deformation of the base metal due to chips clogging the disk-shaped rotary tool can be suppressed.

[0019] 1 is a side view of a disc-shaped rotating tool according to a first embodiment. FIG. 2 is a side view of a disc-shaped rotating tool according to a second embodiment. FIG. 3 is a side view of a disc-shaped rotating tool according to a third embodiment. FIG. 4 is a side view of a disc-shaped rotating tool according to a fourth embodiment. FIG. 5 is a side view of a disc-shaped rotating tool according to a fifth embodiment. FIG. 6 is a side view of a disc-shaped rotating tool according to a sixth embodiment. FIG. 7 is a side view of a disc-shaped rotating tool according to a seventh embodiment. FIG. 8 is a side view of a disc-shaped rotating tool according to an eighth embodiment. FIG. 9 is a graph showing the relationship between the number of overlapping slits in the radial direction and the critical rotation speed. FIG. 10 is a graph showing the relationship between the number of overlapping slits in the radial direction and the maximum axial displacement of the base metal. FIG. 11 is a graph showing the relationship between the angle at which a first slit and another slit overlap in the radial direction and the critical rotation speed. FIG. 12 is a graph showing the relationship between the angle at which a first slit and another slit overlap in the radial direction and the maximum von Mises stress of the base metal. FIG. 13 is a graph showing the relationship between the ratio of the distance between annular regions to the radius of the outer periphery of the disc-shaped rotating tool and the critical rotation speed. FIG. 14 is a graph showing the relationship between the ratio of the distance between annular regions to the radius of the outer periphery of the disc-shaped rotating tool and the maximum displacement of the base metal. 10 is a graph showing the relationship between the diameter of the arc-shaped end portion and the maximum stress generated in the base metal when a tensile stress is applied, and the relationship between the diameter of the arc-shaped end portion and the maximum stress generated in the base metal when a bending load is applied.

[0020] An embodiment of the present disclosure will be described with reference to FIG. 1 . The same reference numerals throughout the description refer to the same elements having the same functions, although redundant description will be omitted. A circular saw blade, also known as a tip saw, is illustrated as an example of a disc-shaped rotary tool 1. As shown in FIG. 1 , the disc-shaped rotary tool 1 includes a disc-shaped base metal 2 and a plurality of tips 5 attached to the outer periphery 2b of the base metal 2. By rotating the base metal 2, each tip 5 forms a groove in the workpiece, ultimately cutting the workpiece. Examples of the workpiece include wood-based materials such as wood and wood board, synthetic resin materials, ceramic-based materials, steel materials such as carbon steel, general structural rolled steel, chromium-molybdenum steel, stainless steel, and cast iron, and non-ferrous metals such as aluminum, aluminum alloys, copper, and copper alloys.

[0021] As shown in FIG. 1 , a substantially circular mounting hole 2a is provided in the center of the base metal 2, penetrating the base metal 2 in the axial direction (thickness direction). The rotary shaft of a disc-shaped rotary tool cutting machine is inserted into the mounting hole 2a. The disc-shaped rotary tool 1 rotates clockwise in the figure to cut a workpiece. The outer diameter of the disc-shaped rotary tool 1 is, for example, 200 mm to 1000 mm, e.g., 355 mm. The base metal 2 is made of steel, e.g., alloy tool steel. The blade thickness of the disc-shaped rotary tool 1 corresponds to the thickness of the tip 5 and is, for example, 0.8 mm to 12.0 mm, e.g., 2.0 mm. The base metal 2 has a plurality of blade bodies 3 protruding radially outward from the outer peripheral edge 2b of the disc-shaped main body. The plurality of blade bodies 3 are formed at regular intervals around the outer peripheral edge 2b. The thickness of the base metal 2 is slightly smaller than the thickness of the tip 5, e.g., 0.6 mm to 10.0 mm, e.g., 1.5 mm.

[0022] As shown in FIG. 1 , a tooth chamber 6 is provided between two adjacent blade bodies 3. A tip seat 4 is formed on each blade body 3 at the front end in the rotational direction, opening circumferentially and radially outward. Tips 5 are attached to each tip seat 4. For example, 20 to 200, e.g., 120, tips 5 are attached to the base metal 2 by brazing or other methods. While the figure shows tips 5 attached to only one blade body 3 for ease of explanation, tips 5 are actually attached to all blade bodies 3. The tips 5 are hard tips made of, for example, cemented carbide, cermet, polycrystalline diamond (PCD) sintered body, or borazon (CBN) sintered body. A cutting edge 5a is provided at the tip of the approximately rectangular parallelepiped tip 5. The cutting edge 5a is located at the radially outer end and the front end of the tip 5 in the rotational direction.

[0023] As shown in FIG. 1 , the base metal 2 is provided with a plurality of external slits 7 extending radially inward from the bottom of the tooth chambers 6. For example, one external slit 7 is provided for every 24 tooth chambers 6, for a total of five external slits 7. The width of the external slits 7 is, for example, 0.1 mm to 2.0 mm, e.g., 0.2 mm. The radially inner ends of the external slits 7 are curved, for example, in a substantially C-shape with a diameter larger than the width of the external slits 7. This makes it possible to suppress stress concentration at the radially inner ends of the external slits 7 and to suppress the occurrence of cracks.

[0024] As shown in FIG. 1 , the base metal 2 is provided with a plurality of slits (internal slits) 10 extending in the circumferential direction. The plurality of slits 10 includes a plurality of first slits 11 arranged in the circumferential direction and a plurality of second slits 12 arranged in the circumferential direction radially outward from the plurality of first slits 11. The plurality of first slits 11 and the plurality of second slits 12 are provided in numbers of, for example, 6 to 14, e.g., 10 each. A first boundary 13a is set on the side surface of the base metal 2, forming a virtual circle centered on the base metal center 2c. The plurality of first slits 11 are all arranged in a first annular region 13 radially inward from the first boundary 13a. On the other hand, the plurality of second slits 12 are all arranged in a second annular region 14 radially outward from the first boundary 13a.

[0025] As shown in FIG. 1 , the first slit 11 has a slit body 11a extending in an arc shape in the circumferential direction. The slit bodies 11a of the multiple first slits 11 are all arranged on a first imaginary circle 11d centered on the base center 2c. The width of the slit body 11a is, for example, 0.1 mm to 2.0 mm, e.g., 0.2 mm. The diameter of the first imaginary circle 11d is, for example, 65% to 85% of the outer diameter of the disc-shaped rotary tool 1, e.g., 72%. The opening angle of one first slit 11 centered on the base center 2c is, for example, 20° to 35°, e.g., 27°. The slit body 11a extends in the circumferential direction by a length equal to or greater than 70% of the total circumferential length of the first slit 11. The slit body 11a extends in the circumferential direction by a length equal to or less than 98% of the total circumferential length of the first slit 11. The multiple first slits 11 are arranged at predetermined intervals on the first imaginary circle 11d.

[0026] As shown in FIG. 1, the first slit 11 has an arc-shaped end 11b at the rear end of the slit body 11a in the rotational direction (the end in the counterclockwise direction in the figure). The first slit 11 has an arc-shaped end 11c at the front end of the slit body 11a in the rotational direction (the end in the clockwise direction in the figure). The arc-shaped ends 11b, 11c are curved in a substantially C-shape with a diameter larger than the width of the slit body 11a. The arc-shaped ends 11b, 11c each open radially inward. The radius of the arc-shaped ends 11b, 11c is, for example, 1.0 mm to 10.0 mm, more preferably 2.0 mm to 4.0 mm, e.g., 2.0 mm. The slit width of the arc-shaped ends 11b, 11c is substantially the same as the width of the slit body 11a. The arc-shaped ends 11 b, 11 c of the approximately C-shape have a stress dispersion effect similar to that of, for example, a circular hole, and their narrow width can prevent chips from entering the arc-shaped ends 11 b, 11 c. By filling the slit body 11 a and the arc-shaped ends 11 b, 11 c with resin, the vibration damping ability of the base metal 2 can be improved and the intrusion of chips into the first slit 11 can be further prevented.

[0027] As shown in FIG. 1 , the second slit 12 has a slit body 12a extending in an arc shape in the circumferential direction. The slit bodies 12a of the multiple second slits 12 are all arranged on a second imaginary circle 12d centered on the base center 2c. The width of the slit body 12a is, for example, 0.1 mm to 2.0 mm, e.g., 0.2 mm. The diameter of the second imaginary circle 12d is, for example, 70% to 90% of the outer diameter of the disc-shaped rotary tool 1, e.g., 80%. The opening angle of one second slit 12 centered on the base center 2c is, for example, 20° to 35°, e.g., 27°. The slit body 12a extends in the circumferential direction by a length equal to or greater than 70% of the entire circumferential length of the second slit 12. The slit body 12a extends in the circumferential direction by a length equal to or less than 98% of the entire circumferential length of the second slit 12. The multiple second slits 12 are arranged at predetermined intervals on the second imaginary circle 12d.

[0028] As shown in FIG. 1 , the second slit 12 has an arc-shaped end 12b at the rear end of the slit body 12a in the rotational direction, and an arc-shaped end 12c at the front end of the slit body 12a in the rotational direction. The arc-shaped ends 12b and 12c are curved in a generally C-shape with a diameter larger than the width of the slit body 12a. The arc-shaped ends 12b and 12c each open radially outward. The radius of the arc-shaped ends 12b and 12c is, for example, 1.0 mm to 10.0 mm, more preferably 2.0 mm to 4.0 mm, e.g., 2.0 mm. The slit width of the arc-shaped ends 12b and 12c is generally the same as the width of the slit body 12a. The generally C-shaped arc-shaped ends 12b and 12c have a stress dispersion effect similar to that of, for example, a circular hole, and their narrow widths can prevent chips from entering the arc-shaped ends 12b and 12c. By filling the slit body 12 a and the arc-shaped ends 12 b and 12 c with resin, the vibration damping properties of the base metal 2 can be improved and the intrusion of chips into the second slit 12 can be further suppressed.

[0029] As shown in FIG. 1 , the first slit 11 and the second slit 12 are arranged to overlap in the radial direction. The first slit 11 radially overlaps with the overlapping region of the second slit 12, which includes the arc-shaped end portion 12c at the front end of the rotational direction, in a region of overlapping width 11e including the arc-shaped end portion 11b at the rear end in the rotational direction. The first slit 11 radially overlaps with the overlapping region of the second slit 12, which includes the arc-shaped end portion 12b at the rear end of the rotational direction, in a region of overlapping width 11f including the arc-shaped end portion 11c at the front end of the rotational direction. The sum of the overlapping width 11e and the overlapping width 11f of the first slit 11 is, for example, 1 / 3 to 1 / 1 of the central angle of the first slit 11, more preferably 1 / 2 to 4 / 5, e.g., 2 / 3. The sum of the overlap width 12e and the overlap width 12f of the second slit 12 is, for example, 1 / 3 to 1 / 1 of the central angle of the second slit 12, more preferably 1 / 2 to 4 / 5, for example 2 / 3.

[0030] As shown in FIG. 1, the average of the sum of the central angles of the plurality of first slits 11 and the sum of the central angles of the plurality of second slits 12 is 180° or more, and more preferably 235° to 300°.

[0031] 1, at least one of the first slits 11 and the second slits 12 is arranged in any region over the entire circumferential length of the base metal 2 centered on the base metal center 2c. Therefore, when an imaginary line extending radially from the base metal center 2c to the outer peripheral edge 2b of the base metal 2 is drawn, at least one slit 10 straddles the imaginary line.

[0032] As described above, the disk-shaped rotating tool 1 has a plurality of slits 10 provided in the disk-shaped base metal 2 as shown in Fig. 1. The plurality of slits 10 includes a plurality of first slits 11 that are circumferentially long and aligned in the circumferential direction within a first annular region 13 of the base metal 2 and do not overlap one another in the radial direction. The plurality of slits 10 also includes a plurality of second slits (other slits) 12 that are arranged in a second annular region (other annular region) 14 so as to radially overlap or contact arc-shaped ends (both ends) 11b, 11c of the plurality of first slits 11. At least one slit 10 exists throughout the entire circumferential length of the base metal 2.

[0033] Therefore, a plurality of first slits 11 are arranged in the first annular region 13, and a plurality of second slits 12 are arranged in the second annular region 14. This allows a larger number of slits 10 to be provided in the base metal 2. As a result, the base metal 2 is more likely to expand radially outward when rotated and centrifugal force acts on it. As a result, the easier it is for the base metal 2 to expand radially outward, the higher the critical rotation speed of the disc-shaped rotating tool 1 can be. Furthermore, by providing a plurality of other annular regions, the base metal 2 is even more likely to expand radially outward. As a result, the base metal 2 can be subjected to a greater centrifugal force. This allows the critical rotation speed of the disc-shaped rotating tool 1 to be further increased.

[0034] As shown in FIG. 1 , the base metal 2 has two radially aligned annular regions 13 and 14. Therefore, two radially aligned annular regions with a plurality of slits 10 can be stacked. This allows the base metal 2 to easily expand radially outward. Furthermore, by not stacking five or more layers, the rigidity of the base metal 2 against axial stress can be ensured. Thus, the critical rotation speed of the disk-shaped rotating tool 1 can be increased while maintaining the rigidity of the base metal 2.

[0035] 1, the first slits 11 each have a slit body 11a that is on the same first imaginary circle 11d and that is aligned with the first imaginary circle 11d. The second slits 12 each have a slit body 12a that is on the same second imaginary circle (another imaginary circle) 12d and that is aligned with the second imaginary circle 12d.

[0036] Therefore, the slit bodies 11a of the multiple first slits 11 are arranged on the first virtual circle 11d, and the slit bodies 12a of the multiple second slits 12 are arranged on the second virtual circle 12d. This allows the radial width of the annular region in which the multiple first slits 11 and multiple second slits 12 are provided to be shortened. Therefore, multiple annular regions can be efficiently overlapped in the radial direction even in a narrow region. This allows the number of slits 10 provided in the base metal 2 to be increased, making it easier for the base metal 2 to expand radially outward. This allows the critical rotation speed of the disc-shaped rotating tool 1 to be increased.

[0037] Furthermore, the slit bodies 11a and 12a are not inclined relative to the circumferential direction. Through extensive research, it has been found that chips tend to get stuck in the inclined portions of the slits 10, which contain components that extend in the radial direction. This makes it possible to prevent chips from getting stuck in the slit bodies 11a and 12a. This also makes it possible to prevent chips from getting stuck in the base metal 2, which would be harmful to cutting.

[0038] 1, both circumferential ends of the plurality of second slits 12 radially overlap with the corresponding first slits 11 at an angle of 1 / 3 to 1 / 1 of the central angle of the corresponding first slit 11. By setting the angle within this range, the critical rotation speed of the disk-shaped rotating tool 1 can be sufficiently increased.

[0039] As shown in FIG. 1 , the first slits 11 and the second slits 12 each have a slit body 11a, 12a with a width of 2.0 mm or less and arcuate end portions 11b, 11c, 12b, 12c with diameters greater than the widths of the slit bodies 11a, 12a. By providing the arcuate end portions 11b, 11c, 12b, 12c at the ends of the slits 10, stress concentration at the ends of the slits 10 can be suppressed. This can prevent cracks from occurring at the ends of the slits 10, where cracks are particularly likely to occur. Furthermore, by providing the slits 10 with a width that allows resin to be filled in, the vibration-damping properties of the disk-shaped rotary tool 1 can be improved.

[0040] Next, a second embodiment of the present disclosure will be described with reference to FIG. 2 . A plurality of slits (internal slits) 21 are provided inside the base metal 2 of a disc-shaped rotary tool 20 of the second embodiment, instead of the plurality of slits 10 shown in FIG. 1 . In the following description, only differences from the first embodiment will be described in detail. The plurality of slits 21 includes a plurality of first slits 22 arranged in the circumferential direction, a plurality of second slits 23 arranged in the circumferential direction radially outward from the plurality of first slits 22, and a plurality of third slits 24 arranged in the circumferential direction radially outward from the plurality of second slits 23. Ten of each of the plurality of first slits 22, the plurality of second slits 23, and the plurality of third slits 24 are provided.

[0041] As shown in Fig. 2, a first boundary 25a and a second boundary 26a are set on the side surface of the base metal 2 as a virtual circle centered on the base metal center 2c. The multiple first slits 22 are all arranged in a first annular region 25 radially inward from the first boundary 25a. The multiple second slits 23 are all arranged in a second annular region 26 radially outward from the first boundary 25a and radially inward from the second boundary 26a. The multiple third slits 24 are all arranged in a third annular region 27 radially outward from the second boundary 26a.

[0042] As shown in FIG. 2 , the first slit 22 has a slit body 22a extending in an arc shape in the circumferential direction. The slit bodies 22a of the multiple first slits 22 are all arranged on a first imaginary circle 22d centered on the base metal center 2c. The width of the slit body 22a is, for example, 0.1 mm to 2.0 mm, e.g., 0.2 mm. The diameter of the first imaginary circle 22d is, for example, 60% to 80% of the outer diameter of the disk-shaped rotary tool 20, e.g., 65%. The opening angle of one first slit 22 centered on the base metal center 2c is, for example, 20° to 35°, e.g., 27°. The slit body 22a extends in the circumferential direction by a length equal to or greater than 70% of the entire circumferential length of the first slit 22. The slit body 22a extends in the circumferential direction by a length equal to or less than 98% of the entire circumferential length of the first slit 22. The first slits 22 are arranged at predetermined intervals on the first virtual circle 22d.

[0043] As shown in Figure 2, the first slit 22 has a generally C-shaped arc-shaped end 22b at the rear end of the slit body 22a in the rotational direction. The first slit 22 has a generally C-shaped arc-shaped end 22c at the front end of the slit body 22a in the rotational direction. The arc-shaped end portions 22b and 22c are provided with the same shape and size as the arc-shaped end portions 11b and 11c (see Figure 1). The arc-shaped end portions 22b and 22c each open radially inward.

[0044] As shown in FIG. 2 , the second slit 23 has a slit body 23a extending in an arc shape in the circumferential direction. The slit bodies 23a of the multiple second slits 23 are all arranged on a second imaginary circle 23d centered on the base metal center 2c. The width of the slit body 23a is, for example, 0.1 mm to 2.0 mm, e.g., 0.2 mm. The diameter of the second imaginary circle 23d is, for example, 65% to 85% of the outer diameter of the disk-shaped rotary tool 20, e.g., 72%. The opening angle of one second slit 23 centered on the base metal center 2c is, for example, 20° to 35°, e.g., 27°. The slit body 23a extends in the circumferential direction by a length equal to or greater than 70% of the entire circumferential length of the second slit 23. The slit body 23a extends in the circumferential direction by a length equal to or less than 98% of the entire circumferential length of the second slit 23. The second slits 23 are arranged at predetermined intervals on the second imaginary circle 23d.

[0045] As shown in Figure 2, the second slit 23 has a generally C-shaped arc-shaped end 23b at the rear end of the slit body 23a in the rotational direction. The second slit 23 has a generally C-shaped arc-shaped end 23c at the front end of the slit body 23a in the rotational direction. The arc-shaped end portions 23b, 23c are provided with the same shape and size as the arc-shaped end portions 11b, 11c (see Figure 1). The arc-shaped end portions 23b, 23c each open radially inward.

[0046] As shown in FIG. 2 , the third slit 24 has a slit body 24a extending in an arc shape in the circumferential direction. The slit bodies 24a of the multiple third slits 24 are all arranged on a third imaginary circle 24d centered on the base metal center 2c. The width of the slit body 24a is, for example, 0.1 mm to 2.0 mm, e.g., 0.2 mm. The diameter of the third imaginary circle 24d is, for example, 70% to 90% of the outer diameter of the disc-shaped rotary tool 20, e.g., 79%. The radial distance between the first imaginary circle 22d and the second imaginary circle 23d is approximately the same as the radial distance between the second imaginary circle 23d and the third imaginary circle 24d. The opening angle of one third slit 24 centered on the base metal center 2c is, for example, 20° to 35°, e.g., 27°. The slit body 24a extends in the circumferential direction by a length equal to or greater than 70% of the entire circumferential length of the third slit 24. The slit body 24a extends in the circumferential direction, for example, by a length equal to or less than 98% of the entire circumferential length of the third slit 24. The third slits 24 are provided at predetermined intervals on the third imaginary circle 24d.

[0047] As shown in FIG. 2 , the third slit 24 has a generally C-shaped arc-shaped end portion 24b at the rear end of the slit body 24a in the rotational direction. The third slit 24 has a generally C-shaped arc-shaped end portion 24c at the front end of the slit body 24a in the rotational direction. The arc-shaped end portions 24b and 24c are formed in the same shape and size as the arc-shaped end portions 12b and 12c (see FIG. 1 ). The arc-shaped end portions 24b and 24c each open radially outward. Filling the slit bodies 22a, 23a, and 24a and the arc-shaped end portions 22b, 22c, 23b, 23c, 24b, and 24c of each slit 21 with resin improves the vibration damping of the base metal 2 and further suppresses the intrusion of chips into the slits 21.

[0048] As shown in FIG. 2 , the first slits 22 and the second slits 23 are arranged to overlap in the radial direction. The first slits 22 radially overlap with an overlapping region of width 23f including the arc-shaped end portion 22b at the rear end in the rotational direction of the second slits 23. The first slits 22 radially overlap with an overlapping region of width 23f including the arc-shaped end portion 23c at the front end in the rotational direction of the second slits 23. The first slits 22 radially overlap with an overlapping region of width 23e including the arc-shaped end portion 23b at the rear end in the rotational direction of the second slits 23. The sum of the overlapping widths 22e and 22f of the first slits 22 is, for example, 1 / 3 to 1 / 1 of the central angle of the first slit 22, more preferably 1 / 2 to 4 / 5, e.g., 2 / 3. The sum of the overlap width 23e and the overlap width 23f of the second slit 23 is, for example, 1 / 3 to 1 / 1 of the central angle of the second slit 23, more preferably 1 / 2 to 4 / 5, for example 2 / 3.

[0049] 2, the second slits 23 and the third slits 24 are arranged to overlap in the radial direction. The region of overlapping width 23e of the second slits 23 overlaps in the radial direction with the region of overlapping width 24f including the arc-shaped end portions 24c at the front ends of the third slits 24 in the rotational direction. The region of overlapping width 23f of the second slits 23 overlaps in the radial direction with the region of overlapping width 24e including the arc-shaped end portions 24b at the rear ends of the third slits 24 in the rotational direction. The sum of the overlapping widths 24e and 24f of the third slits 24 is, for example, 1 / 3 to 1 / 1 of the central angle of the third slits 24, more preferably 1 / 2 to 4 / 5, e.g., 2 / 3.

[0050] As shown in FIG. 2, the average of the sum of the central angles of the plurality of first slits 22, the sum of the central angles of the plurality of second slits 23, and the sum of the central angles of the plurality of third slits 24 is 180° or more, and more preferably 235° to 300°.

[0051] 2, the first slits 22 and the third slits 24 are arranged so that they overlap substantially entirely in the radial direction. The arc-shaped ends 22b, 22c of the first slits 22 and the arc-shaped ends 24b, 24c of the third slits 24 overlap in the radial direction, respectively. At least one of the first slits 22, the second slits 23, and the third slits 24 is arranged in any region along the entire circumferential length of the base metal 2 centered on the base metal center 2c. Therefore, when an imaginary line extending radially from the base metal center 2c to the outer peripheral edge 2b of the base metal 2 is drawn, at least one slit 21 straddles the imaginary line.

[0052] The above-described disk-shaped rotary tool 20 has the same effects as the disk-shaped rotary tool 1 shown in Fig. 1. Moreover, by arranging the plurality of circumferentially extending slits 21 in three layers in the radial direction, the base metal 2 is more likely to expand radially outward by centrifugal force. This makes it possible to further increase the critical rotation speed of the disk-shaped rotary tool 20.

[0053] Next, a third embodiment of the present disclosure will be described with reference to FIG. 3 . The base metal 2 of a disc-shaped rotary tool 40 of the third embodiment is provided with a plurality of slits (internal slits) 41 instead of the plurality of slits 10 shown in FIG. 1 . In the following description, only differences from the first embodiment will be described in detail. The plurality of slits 41 includes a plurality of first slits 42 arranged in the circumferential direction and a plurality of second slits 43 arranged in the circumferential direction radially outward from the plurality of first slits 42. The plurality of slits 41 also includes a plurality of third slits 44 arranged in the circumferential direction radially outward from the plurality of second slits 43, and a plurality of fourth slits 45 arranged in the circumferential direction radially outward from the plurality of third slits 44. Twelve of each of the plurality of first slits 42, the plurality of second slits 43, the plurality of third slits 44, and the plurality of fourth slits 45 are provided.

[0054] As shown in Figure 3, consider a first boundary 46a, a second boundary 47a, and a third boundary 48a of a virtual circle centered on the base center 2c on the side surface of the base 2. The multiple first slits 42 are all arranged in a first annular region 46 radially inward from the first boundary 46a. The multiple second slits 43 are all arranged in a second annular region 47 radially outward from the first boundary 46a and radially inward from the second boundary 47a. The multiple third slits 44 are all arranged in a third annular region 48 radially outward from the second boundary 47a and radially inward from the third boundary 48a. The multiple fourth slits 45 are all arranged in a fourth annular region 49 radially outward from the third boundary 48a.

[0055] As shown in FIG. 3 , the first slit 42 has a slit body 42a extending in an arc shape in the circumferential direction. The slit bodies 42a of the multiple first slits 42 are all arranged on a first imaginary circle 42d centered on the base center 2c. The width of the slit body 42a is, for example, 0.1 mm to 2.0 mm, e.g., 0.2 mm. The diameter of the first imaginary circle 42d is, for example, 55% to 75% of the outer diameter of the disk-shaped rotary tool 40, e.g., 60%. The opening angle of one first slit 42 centered on the base center 2c is, for example, 20° to 35°, e.g., 20°. The slit body 42a extends in the circumferential direction by a length equal to or greater than 70% of the entire circumferential length of the first slit 42. The slit body 42a extends in the circumferential direction by a length equal to or less than 98% of the entire circumferential length of the first slit 42. The first slits 42 are arranged at predetermined intervals on the first virtual circle 42d.

[0056] As shown in Figure 3, the first slit 42 has a generally C-shaped arc-shaped end 42b at the rear end of the slit body 42a in the rotational direction. The first slit 42 has a generally C-shaped arc-shaped end 42c at the front end of the slit body 42a in the rotational direction. The arc-shaped end portions 42b, 42c are provided with the same shape and size as the arc-shaped end portions 11b, 11c (see Figure 1). The arc-shaped end portions 42b, 42c each open radially inward.

[0057] As shown in FIG. 3 , the second slit 43 has a slit body 43a extending in an arc shape in the circumferential direction. The slit bodies 43a of the multiple second slits 43 are all arranged on a second imaginary circle 43d centered on the base center 2c. The width of the slit body 43a is, for example, 0.1 mm to 2.0 mm, e.g., 0.2 mm. The diameter of the second imaginary circle 43d is, for example, 60% to 80% of the outer diameter of the disk-shaped rotary tool 40, e.g., 66%. The opening angle of one second slit 43 centered on the base center 2c is, for example, 20° to 35°, e.g., 20°. The slit body 43a extends in the circumferential direction by a length equal to or greater than 70% of the entire circumferential length of the second slit 43. The slit body 43a extends in the circumferential direction by a length equal to or less than 98% of the entire circumferential length of the second slit 43. The second slits 43 are arranged at predetermined intervals on the second virtual circle 43d.

[0058] As shown in Figure 3, the second slit 43 has a generally C-shaped arc-shaped end 43b at the rear end of the slit body 43a in the rotational direction. The second slit 43 has a generally C-shaped arc-shaped end 43c at the front end of the slit body 43a in the rotational direction. The arc-shaped end portions 43b, 43c are provided with the same shape and size as the arc-shaped end portions 11b, 11c (see Figure 1). The arc-shaped end portions 43b, 43c each open radially inward.

[0059] As shown in FIG. 3 , the third slit 44 has a slit body 44a extending in an arc shape in the circumferential direction. The slit bodies 44a of the multiple third slits 44 are all arranged on a third imaginary circle 44d centered on the base center 2c. The width of the slit body 44a is, for example, 0.1 mm to 2.0 mm, e.g., 0.2 mm. The diameter of the third imaginary circle 44d is, for example, 65% to 85% of the outer diameter of the disk-shaped rotary tool 40, e.g., 73%. The opening angle of one third slit 44 centered on the base center 2c is, for example, 20° to 35°, e.g., 20°. The slit body 44a extends in the circumferential direction by a length equal to or greater than 70% of the entire circumferential length of the third slit 44. The slit body 44a extends in the circumferential direction by a length equal to or less than 98% of the entire circumferential length of the third slit 44. The third slits 44 are provided at predetermined intervals on the third imaginary circle 44d.

[0060] As shown in Figure 3, the third slit 44 has a generally C-shaped arc-shaped end 44b at the rear end of the slit body 44a in the rotational direction. The third slit 44 has a generally C-shaped arc-shaped end 44c at the front end of the slit body 44a in the rotational direction. The arc-shaped end portions 44b, 44c are provided with the same shape and size as the arc-shaped end portions 11b, 11c (see Figure 1). The arc-shaped end portions 44b, 44c each open radially inward.

[0061] As shown in FIG. 3 , the fourth slit 45 has a slit body 45a extending in an arc shape in the circumferential direction. The slit bodies 45a of the multiple fourth slits 45 are all arranged on a fourth virtual circle 45d centered on the base center 2c. The width of the slit body 45a is, for example, 0.1 mm to 2.0 mm, e.g., 0.2 mm. The diameter of the fourth virtual circle 45d is, for example, 70% to 90% of the outer diameter of the disk-shaped rotary tool 40, e.g., 79%. The radial distance between the first virtual circle 42d and the second virtual circle 43d, the radial distance between the second virtual circle 43d and the third virtual circle 44d, and the distance between the third virtual circle 44d and the fourth virtual circle 45d are substantially the same. The opening angle of one fourth slit 45 centered on the base center 2c is, for example, 20° to 35°, e.g., 20°. The slit body 45a extends in the circumferential direction by a length equal to or greater than 70% of the entire circumferential length of the fourth slit 45. For example, the slit body 45a extends in the circumferential direction by a length equal to or less than 98% of the entire circumferential length of the fourth slit 45. The multiple fourth slits 45 are provided at predetermined intervals on the fourth virtual circle 45d.

[0062] As shown in FIG. 3 , the fourth slit 45 has a generally C-shaped arc-shaped end 45b at the rear end of the slit body 45a in the rotational direction. The fourth slit 45 has a generally C-shaped arc-shaped end 45c at the front end of the slit body 45a in the rotational direction. The arc-shaped ends 45b, 45c are formed in the same shape and size as the arc-shaped ends 12b, 12c (see FIG. 1 ). The arc-shaped ends 45b, 45c each open radially outward. Filling the slit bodies 42a, 43a, 44a, 45a and the arc-shaped ends 42b, 42c, 43b, 43c, 44b, 44c, 45b, 45c of each slit 41 with resin improves the vibration damping of the base metal 2 and further suppresses the intrusion of chips into the slit 41.

[0063] As shown in FIG. 3 , the first slits 42 and the second slits 43 are arranged to overlap in the radial direction. The first slits 42 radially overlap with an overlapping region 43f including the arc-shaped end 43c at the front end of the second slits 43 in the rotational direction, in a region of overlapping width 42e that includes the arc-shaped end 42b at the rear end in the rotational direction. The first slits 42 radially overlap with an overlapping region 43e including the arc-shaped end 43b at the rear end in the rotational direction of the second slits 43, in a region of overlapping width 42f that includes the arc-shaped end 42c at the front end in the rotational direction. The sum of the overlapping widths 42e and 42f of the first slits 42 is, for example, 1 / 3 to 1 / 1 of the central angle of the first slit 42, more preferably 1 / 2 to 4 / 5, e.g., 2 / 3. The sum of the overlap width 43e and the overlap width 43f of the second slit 43 is, for example, 1 / 3 to 1 / 1 of the central angle of the second slit 43, more preferably 1 / 2 to 4 / 5, for example 2 / 3.

[0064] 3, the second slits 43 and the third slits 44 are arranged to overlap in the radial direction. The region of overlapping width 43e of the second slits 43 radially overlaps with the region of overlapping width 44f including the arc-shaped end portion 44c at the front end in the rotational direction of the third slits 44. The region of overlapping width 43f of the second slits 43 radially overlaps with the region of overlapping width 44e including the arc-shaped end portion 44b at the rear end in the rotational direction of the third slits 44. The sum of the overlapping widths 44e and 44f of the third slits 44 is, for example, 1 / 3 to 1 / 1 of the central angle of the third slit 44, more preferably 1 / 2 to 4 / 5, e.g., 2 / 3.

[0065] 3, the third slits 44 and the fourth slits 45 are arranged to overlap in the radial direction. The region of overlapping width 44e of the third slits 44 overlaps in the radial direction with the region of overlapping width 45f including the arc-shaped end portion 45c at the front end in the rotational direction of the fourth slits 45. The region of overlapping width 44f of the third slits 44 overlaps in the radial direction with the region of overlapping width 45e including the arc-shaped end portion 45b at the rear end in the rotational direction of the fourth slits 45. The sum of the overlapping widths 45e and 45f of the fourth slits 45 is, for example, 1 / 3 to 1 / 1 of the central angle of the fourth slit 45, more preferably 1 / 2 to 4 / 5, e.g., 2 / 3.

[0066] As shown in FIG. 3, the average of the sum of the central angles of the plurality of first slits 42, the sum of the central angles of the plurality of second slits 43, the sum of the central angles of the plurality of third slits 44, and the sum of the central angles of the plurality of fourth slits 45 is 180° or more, and more preferably 235° to 300°.

[0067] As shown in FIG. 3 , the first slits 42 and the third slits 44 are arranged so that they overlap substantially entirely in the radial direction. The arc-shaped ends 42b and 42c of the first slit 42 and the arc-shaped ends 44b and 44c of the third slit 44 overlap in the radial direction, respectively. The second slits 43 and the fourth slits 45 are arranged so that they overlap substantially entirely in the radial direction. The arc-shaped ends 43b and 43c of the second slit 43 and the arc-shaped ends 45b and 45c of the fourth slit 45 overlap in the radial direction, respectively. At least one of the first slits 42, the second slits 43, and the third slits 44 is arranged in any region along the entire circumferential length of the base 2 centered on the base center 2c. Therefore, when an imaginary line extending radially from the base center 2c to the outer peripheral edge 2b of the base 2 is drawn, at least one slit 41 straddles the imaginary line.

[0068] The above-described disk-shaped rotary tool 40 exhibits the same effects as the disk-shaped rotary tool 1 shown in Fig. 1. Moreover, by arranging the multiple circumferentially extending slits 41 in four layers in the radial direction, the base metal 2 is more likely to expand radially outward due to centrifugal force. This allows the critical rotation speed of the disk-shaped rotary tool 40 to be further increased.

[0069] Next, a fourth embodiment of the present disclosure will be described with reference to FIG. 4 . A disk-shaped rotary tool 50 of the fourth embodiment has a base 2 provided with a plurality of slits (internal slits) 51 instead of the plurality of slits 10 shown in FIG. In the following description, only differences from the first embodiment will be described in detail. The plurality of slits 51 includes a plurality of first slits 52 arranged in the circumferential direction and a plurality of second slits 53 arranged in the circumferential direction radially outward from the plurality of first slits 52. For example, ten first slits 52 and ten second slits 53 are provided. Consider a first boundary 54a of an imaginary circle centered on the base center 2c on the side surface of the base 2. The first slits 52 are all arranged in a first annular region 54 radially inward from the first boundary 54a. The second slits 53 are all arranged in a second annular region 55 radially outward from the first boundary 54a.

[0070] As shown in FIG. 4 , the first slit 52 has a slit body 52a extending in an arc shape in the circumferential direction. The slit bodies 52a of the multiple first slits 52 are all arranged on a first imaginary circle 52d centered on the base center 2c. The width of the slit body 52a is, for example, 1.0 mm to 10.0 mm, and is a constant width of, for example, 4.0 mm. The diameter of the first imaginary circle 52d is, for example, 65% to 85% of the outer diameter of the disk-shaped rotary tool 50, for example, 72%. The opening angle of one first slit 52 centered on the base center 2c is, for example, 20° to 35°, and is, for example, 27°. The slit body 52a extends in the circumferential direction by a length equal to or greater than 70% of the entire circumferential length of the first slit 52. For example, the slit body 52a extends in the circumferential direction by a length equal to or less than 99% of the entire circumferential length of the first slit 52. The first slits 52 are arranged at predetermined intervals on the first imaginary circle 52d.

[0071] As shown in Figure 4, the first slit 52 has an arc-shaped end 52b at the rear end of the slit body 52a in the rotational direction. The first slit 52 has an arc-shaped end 52c at the front end of the slit body 52a in the rotational direction. The arc-shaped ends 52b, 52c are formed in a semicircular shape with a diameter approximately equal to the width of the slit body 52a. The slit body 52a and the arc-shaped ends 52b, 52c may or may not be filled with a resin to improve vibration damping.

[0072] As shown in FIG. 4 , the second slit 53 has a slit body 53a extending in an arc shape in the circumferential direction. The slit bodies 53a of the multiple second slits 53 are all arranged on a second imaginary circle 53d centered on the base center 2c. The width of the slit body 53a is, for example, 1.0 mm to 10.0 mm, and is a constant width of, for example, 4.0 mm. The diameter of the second imaginary circle 53d is, for example, 70% to 90% of the outer diameter of the disk-shaped rotary tool 50, for example, 80%. The opening angle of one second slit 53 centered on the base center 2c is, for example, 20° to 35°, and is, for example, 27°. The slit body 53a extends in the circumferential direction by a length equal to or greater than 70% of the entire circumferential length of the second slit 53. For example, the slit body 53a extends in the circumferential direction by a length equal to or less than 99% of the entire circumferential length of the second slit 53. The second slits 53 are arranged at predetermined intervals on the second imaginary circle 53d.

[0073] As shown in Figure 4, the second slit 53 has an arc-shaped end 53b at the rear end of the slit body 53a in the rotational direction. The second slit 53 has an arc-shaped end 53c at the front end of the slit body 53a in the rotational direction. The arc-shaped ends 53b, 53c are formed in a semicircular shape with a diameter approximately equal to the width of the slit body 53a. The slit body 53a and the arc-shaped ends 53b, 53c may or may not be filled with a resin to improve vibration damping.

[0074] As shown in FIG. 4 , the first slits 52 and the second slits 53 are arranged to overlap in the radial direction. The first slits 52 radially overlap with an overlapping region 53f of the second slits 53 including the arc-shaped end portions 53c of the front ends of the second slits 53 in the rotational direction in a region of overlapping width 52e that includes the arc-shaped end portions 52b of the rear ends of the first slits 52 in the rotational direction. The first slits 52 radially overlap with an overlapping region 53e of the second slits 53 including the arc-shaped end portions 53b of the rear ends of the second slits 53 in the rotational direction in a region of overlapping width 52f that includes the arc-shaped end portions 52c of the front ends of the first slits 52 in the rotational direction. The sum of the overlapping widths 52e and 52f of the first slits 52 is, for example, 1 / 3 to 1 / 1 of the central angle of the first slits 52, more preferably 1 / 2 to 4 / 5, e.g., 2 / 3. The sum of the overlap width 53e and the overlap width 53f of the second slit 53 is, for example, 1 / 3 to 1 / 1 of the central angle of the second slit 53, more preferably 1 / 2 to 4 / 5, for example 2 / 3.

[0075] As shown in FIG. 4, the average of the sum of the central angles of the plurality of first slits 52 and the sum of the central angles of the plurality of second slits 53 is 180° or more, and more preferably 235° to 300°.

[0076] 4, at least one of the first slits 52 or the second slits 53 is arranged in any region over the entire circumferential length of the base metal 2 centered on the base metal center 2c. Therefore, when an imaginary line extending radially from the base metal center 2c to the outer peripheral edge 2b of the base metal 2 is drawn, at least one slit 51 straddles the imaginary line.

[0077] The above-described disk-shaped rotary tool 50 achieves the same effects as the disk-shaped rotary tool 1 shown in FIG. 1 . Furthermore, as shown in FIG. 4 , the plurality of first slits 52 and the plurality of second slits (other slits) 53 each have a slit body 52a, 53a with a width of 1.0 mm to 10.0 mm and arc-shaped end portions 52b, 52c, 53b, 53c with diameters substantially equal to the widths of the slit bodies 52a, 53a. By providing the arc-shaped end portions 52b, 52c, 53b, 53c at the ends of the slits 51, stress concentration at the ends of the slits 51 can be suppressed, thereby preventing cracks from occurring. Furthermore, by forming the slits 51 as through-holes with a width sufficient for chips to pass through without being filled with resin or the like, deformation of the base metal 2 due to chips clogging the disk-shaped rotary tool 50 can be suppressed.

[0078] A fifth embodiment of the present disclosure is shown in Fig. 5. A plurality of slits (internal slits) 61 are provided inside the base metal 2 of a disk-shaped rotary tool 60 of the fifth embodiment, instead of the plurality of slits 10 shown in Fig. 1. The plurality of slits 61 include a plurality of first slits 62 arranged in the circumferential direction and a plurality of second slits 63 arranged in the circumferential direction and radially outward of the plurality of first slits 62.

[0079] As shown in FIG. 5 , the first slit 62 has an arc-shaped end 62b at the rear end of the slit body 62a in the rotational direction. The first slit 62 has an arc-shaped end 62c at the front end of the slit body 62a in the rotational direction. The second slit 63 has an arc-shaped end 63b at the rear end of the slit body 63a in the rotational direction. The second slit 63 has an arc-shaped end 63c at the front end of the slit body 63a in the rotational direction. The arc-shaped ends 62b, 62c, 63b, and 63c are provided in circular holes with a diameter larger than the width of the slit bodies 62a and 63a. The diameter of the arc-shaped ends 62b, 62c, 63b, and 63c is, for example, 1.0 mm to 10.0 mm, more preferably 2.0 mm to 4.0 mm, e.g., 2.0 mm. According to the above-described disk-shaped rotary tool 60, even when the arc-shaped end portions 62b, 62c, 63b, 63c are circular holes, the same effects as those of the disk-shaped rotary tool 1 shown in FIG. 1 can be achieved.

[0080] Next, a sixth embodiment of the present disclosure is shown in FIG. 6 . A disk-shaped rotary tool 70 of the sixth embodiment has a base metal 2 provided with a plurality of slits (internal slits) 71 instead of the plurality of slits 10 shown in FIG. 1 . The plurality of slits 71 includes a plurality of first slits 72 arranged in the circumferential direction and a plurality of second slits 73 arranged in the circumferential direction and radially outward from the plurality of first slits 72. The plurality of first slits 72 are all arranged in a first annular region 74 radially inward from a first boundary 74a of an imaginary circle centered on the base metal center 2c. The plurality of second slits 73 are all arranged in a second annular region 75 radially outward from the first boundary 74a.

[0081] As shown in Figure 6, the first slit 72 has a slit body 72a that extends in an arc shape in a generally circumferential direction. The slit body 72a is inclined radially inward from the front to the rear in the direction of rotation. The second slit 73 has a slit body 73a that extends in an arc shape in a generally circumferential direction. The slit body 73a is inclined radially inward from the front to the rear in the direction of rotation. The above-described disc-shaped rotary tool 70 provides the same effects as the disc-shaped rotary tool 1 shown in Figure 1.

[0082] Next, a seventh embodiment of the present disclosure is shown in FIG. 7 . A disk-shaped rotary tool 80 of the seventh embodiment has a base metal 2 provided with a plurality of slits (internal slits) 81 instead of the plurality of slits 10 shown in FIG. 1 . In the following description, the plurality of slits 81 includes a plurality of first slits 82 arranged in the circumferential direction and a plurality of second slits 83 arranged in the circumferential direction and radially outward from the plurality of first slits 82. The plurality of first slits 82 are all arranged in a first annular region 84 radially inward from a first boundary 84a of an imaginary circle centered on the base metal center 2c. The plurality of second slits 83 are all arranged in a second annular region 85 radially outward from the first boundary 84a.

[0083] As shown in Fig. 7, the first slit 82 has a slit body 82a extending linearly. The slit body 82a is perpendicular to the radial direction at the circumferential center. The second slit 83 has a slit body 83a extending linearly. The slit body 83a is perpendicular to the radial direction at the circumferential center. The above-described disk-shaped rotary tool 80 provides the same effects as the disk-shaped rotary tool 1 shown in Fig. 1.

[0084] Next, an eighth embodiment of the present disclosure is shown in FIG. 8 . A disk-shaped rotary tool 90 of the eighth embodiment has a base metal 2 provided with a plurality of slits (internal slits) 91 instead of the plurality of slits 10 shown in FIG. 1 . The plurality of slits 91 includes a plurality of first slits 92 arranged in the circumferential direction and a plurality of second slits 93 arranged in the circumferential direction and radially outward from the plurality of first slits 92. The plurality of first slits 92 are all arranged in a first annular region 94 radially inward from a first boundary 94a of an imaginary circle centered on the base metal center 2c. The plurality of second slits 93 are all arranged in a second annular region 95 radially outward from the first boundary 94a.

[0085] As shown in Fig. 8, the first slit 92 has a slit body 92a extending generally in the circumferential direction. The slit body 92a is formed in a wavy, meandering shape in the radial direction. The slit body 92a is generally perpendicular to the radial direction at the circumferential center. The second slit 93 has a slit body 93a extending generally in the circumferential direction. The slit body 93a is formed in a wavy, meandering shape in the radial direction. The slit body 93a is generally perpendicular to the radial direction at the circumferential center. The disc-shaped rotary tool 90 described above provides the same effects as the disc-shaped rotary tool 1 shown in Fig. 1.

[0086] 9 to 14, static analysis and modal analysis simulations were performed on the disk-shaped rotating tool of the present disclosure. In the static analysis, the maximum von Mises stress and maximum displacement generated in the base 2 when stress was applied to the tip of the cutting element 3 in the axial direction of the base 2 were evaluated. The critical rotation speed of the base 2 was calculated from the modal analysis.

[0087] As shown in Figures 9 and 10, the critical rotation speed and maximum displacement of the base metal were evaluated when the number of annular regions, in which rows of circumferentially arranged slits are overlapped radially, was changed. For example, when the number of annular regions is 2, it corresponds to the disk-shaped rotating tool 1 shown in Figure 1. For example, when the number of annular regions is 3, it corresponds to the disk-shaped rotating tool 20 shown in Figure 2. For example, when the number of annular regions is 4, it corresponds to the disk-shaped rotating tool 40 shown in Figure 3. In the analysis, the maximum displacement of the base metal increased linearly as the number of annular regions increased.

[0088] As shown in Figures 9 and 10, the critical rotation speed of the base metal increases as the number of annular regions increases, but the increase rate decreases as the number of annular regions increases. Considering that the critical rotation speed of the base metal should be as high as possible and the maximum displacement of the base metal should be as small as possible, the preferable range of the number of annular regions was determined to be 2 to 4 layers.

[0089] As shown in Figures 11 and 12, the critical rotation speed and maximum von Mises stress of the base metal were evaluated when the overlap width, the radial overlap width between the first slit and the other slits, was changed. The overlap width is the width by which one first slit overlaps with another slit in the radial direction, expressed as an angle with the center of the base metal as the center. For example, an overlap width of 0° indicates a state in which the first slit and the other slits do not overlap at all in the radial direction.

[0090] As shown in Figures 11 and 12, the maximum von Mises stress generated in the base metal decreased linearly with an increase in the overlap width within the analyzed range. Although the critical rotation speed of the base metal increased as the overlap width increased, the amount of increase decreased as the overlap width increased. In particular, the increase in the critical rotation speed was slight when the overlap width was increased from 10° to 12°. Considering that the increase in the critical rotation speed of the base metal should be relatively large and the maximum von Mises stress of the base metal should be as low as possible, the preferred overlap width range is 1 / 6 to 1 / 2 of the total circumferential length of the slit, and the more preferred overlap width range is 1 / 4 to 2 / 5 of the total circumferential length of the slit.

[0091] As shown in Figures 13 and 14, the critical rotation speed and maximum displacement of the base metal were evaluated when the ratio of the difference in radius between the first virtual circle and the other virtual circles (the distance between the annular regions) to the outer radius of the disk-shaped rotating tool was changed. As shown in Figure 13, the critical rotation speed of the base metal increased as the ratio of the difference in radius between the first virtual circle and the other virtual circles to the outer radius of the disk-shaped rotating tool decreased, but there was almost no change when the ratio was less than 4%. As shown in Figure 14, the maximum displacement of the base metal increased significantly when the ratio of the difference in radius between the first virtual circle and the other virtual circles to the outer radius of the disk-shaped rotating tool was less than 4% and also increased when it exceeded 15%. From the above, considering the need to increase the critical rotation speed of the base metal and minimize the displacement of the base metal, a preferable range of the ratio of the difference in radius between the first virtual circle and the other virtual circles to the outer radius of the disk-shaped rotating tool is 4% to 15%.

[0092] A simulation was performed to analyze the maximum stress generated in the base metal when the diameter of the arc-shaped end portion of the disk-shaped rotary tool of the present disclosure was changed, as shown in Figures 15 and 16. The slit was linear, extending straight in the lateral direction, with a width of 0.2 mm and a length of 30 mm including the arc-shaped end portion, and circular holes with arc-shaped end portions were provided on both ends of the slit.

[0093] Figure 15 shows the maximum stress generated in the base metal when a constant force is applied to the base metal in a direction perpendicular to the slit on the base metal plane. This reproduces the centrifugal force generated when the base metal rotates at high speed. The analysis showed that the maximum stress generated in the base metal decreased as the diameter of the arc-shaped end increased, but the amount of reduction also decreased as the diameter of the arc-shaped end increased. The amount of reduction in tensile stress decreased particularly when the diameter of the arc-shaped end was greater than 4.0 mm.

[0094] Figure 16 shows the maximum stress generated in the base metal when the base metal is fixed and a constant force is applied in the thickness direction. This reproduces the axial bending load received from the workpiece when the base metal is rotating at high speed. In the analysis, the bending load generated in the base metal decreased as the diameter of the arc-shaped end portion increased, but the amount of reduction also decreased as the diameter of the arc-shaped end portion increased. In particular, the amount of reduction in tensile stress decreased when the diameter of the arc-shaped end portion was greater than 4.0 mm. From the above, the preferable range for the diameter of the arc-shaped end portion is 2.0 mm to 4.0 mm.

[0095] The above analyses allow us to determine the shape, arrangement, etc. of the slits that can increase the critical rotation speed and improve the rigidity of the base metal. Based on the results of this determination, the disk-shaped rotating tool according to each embodiment of the present disclosure can be provided.

[0096] Various modifications can be made to the disk-shaped rotary tools of the above-described embodiments. A tip saw to which multiple tips 5 are attached has been exemplified as the disk-shaped rotary tool. Instead, the present disclosure may be applied to, for example, a circular saw blade in which a cutting edge is provided directly at the tip of the blade body 3. For example, the present disclosure may be applied to disk-shaped rotary tools other than tip saws and circular saw blades.

[0097] In the illustrated example, the first slits and the other slits are provided in numbers of 10 or 12. Alternatively, the first slits and the other slits may be provided in any number within a range of 6 to 14. In the illustrated example, the first slits and the other slits are provided in equal numbers. Alternatively, the first slits and the other slits may be provided in different numbers, as long as the condition that there is at least one slit along the entire circumferential length of the base metal is satisfied.

[0098] 2 and 3 show an example of a disk-shaped rotary tool in which the third slits 24, 44 overlap substantially entirely with the first slits 22, 42 in the radial direction. Fig. 3 shows an example of a disk-shaped rotary tool in which the fourth slit 45 overlaps substantially entirely with the second slit in the radial direction. Alternatively, for example, the first slit and the third slit may have a range in which they do not overlap with each other in the radial direction. For example, the second slit and the fourth slit may have a range in which they do not overlap with each other in the radial direction.

[0099] 1 to 8 show an example of a configuration in which the overlap width of the first slit with other slits in the radial direction is approximately the same at the front end in the rotational direction and at the rear end in the rotational direction. Alternatively, the overlap width at the front end in the rotational direction and the overlap width at the rear end in the rotational direction may be different lengths. 1 to 8 show an example of a configuration in which the slits are arranged so that the radial spacing between each virtual circle is approximately constant. Alternatively, the radial spacing between each virtual circle does not have to be constant.

[0100] Figures 1 to 8 illustrate a configuration in which arc-shaped ends are provided at both ends of the slit body. Alternatively, for example, an arc-shaped end may be provided only at the front end of the slit body in the rotational direction. For example, an arc-shaped end may be provided only at the rear end of the slit body in the rotational direction. Figures 1 to 3 and 6 to 8 illustrate a substantially C-shaped arc-shaped end that opens radially inward or radially outward. The opening direction of each arc-shaped end may be changed as appropriate. For example, Figures 1 to 3 and 6 to 8 illustrate a configuration in which all first slits have arc-shaped ends that open radially inward. Alternatively, the opening direction of the arc-shaped end may differ for each slit. For example, Figures 1 to 3 and 6 to 8 illustrate a configuration in which the arc-shaped ends at both ends of a single slit open in the same direction. Alternatively, the arc-shaped ends at both ends of a single slit may open in different directions. One of the arc-shaped ends at both ends of the slit may be replaced with, for example, a circular hole.

[0101] 6 shows an example of a disk-shaped rotary tool 70 having a plurality of slits 71 that are inclined radially inward from the front to the rear in the direction of rotation. Alternatively, for example, the plurality of slits may be inclined radially outward from the front to the rear in the direction of rotation. For example, the inclination directions of the first slit and the other slits may be different from each other.

[0102] 1 to 8 show an example of a configuration in which multiple slits provided in one disk-shaped rotary tool have the same shape. Alternatively, multiple types of slit shapes may be mixed, for example, the first slit may have the shape of slit 10 in the first embodiment, the second slit may have the shape of slit 51 in the fourth embodiment, and the third slit may have the shape of slit 61 in the fifth embodiment.

Claims

1. A disk-shaped rotating tool having a plurality of slits provided in a disk-shaped base metal, the plurality of slits including: a plurality of first slits which are long and aligned circumferentially within a first annular region of the base metal and do not radially overlap one another; and a plurality of other slits which are arranged within another annular region so as to radially overlap or contact each end of the plurality of first slits, and at least one of the slits is present along the entire circumferential length of the base metal.

2. A disk-shaped rotating tool according to claim 1, wherein the base metal has two to four layers of annular regions arranged in the radial direction, and a plurality of slits are formed in each annular region.

3. A disk-shaped rotating tool as described in claim 1 or 2, wherein the plurality of first slits each have a slit body that is on the same first imaginary circle and aligned with the first imaginary circle, and the plurality of other slits each have a slit body that is on the same other imaginary circle and aligned with the other imaginary circle.

4. A disk-shaped rotating tool according to claim 1 or 2, wherein each of the circumferential ends of the plurality of other slits radially overlaps with the corresponding first slit at an angle of 1 / 3 to 1 / 1 of the central angle of the corresponding first slit.

5. A disk-shaped rotating tool according to claim 1 or 2, wherein the plurality of first slits and the plurality of other slits each have a slit body having a width of 2.0 mm or less and an arc-shaped end portion having a diameter greater than the width of the slit body.

6. A disk-shaped rotating tool according to claim 1 or 2, wherein the plurality of first slits and the plurality of other slits each have a slit body with a width of 1.0 mm to 10.0 mm and an arc-shaped end portion with a diameter substantially the same as the width of the slit body.

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