JP7020717B1 - Rotating blade - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary cutting tool capable of improving workability without damaging adjacent objects to be ground even when the objects to be ground are close to each other. SOLUTION: A rotary cutting tool 1 is covered from a flange type base metal 10 having a screw hole 111a screwed in a central inner wall in parallel with an axial center and forming a perfect circle in a top view, and a flange surface 11a of the base metal 10. It has a plurality of grinding blades 15a to 15f erected on the ground object side. The plurality of grinding blades 15a to 15f form a three-dimensional chip region 15 on the flange surface 11a when the base metal 10 rotates about the axis. Further, the outer diameter of the flange surface 11a is larger than the outer diameter of the chip region 15. [Selection diagram] Fig. 1

Description

The present invention relates to a three-dimensional rotary cutting tool used for construction such as grinding the surface of a building such as tiles and mortar or peeling off a coating film.

There are straight type and cup type rotary cutting tools used for this kind of construction. In the straight type rotary cutting tool, a grinding blade called a tip is formed on the peripheral edge of a disk-shaped substrate. In the cup-shaped rotary cutting tool, the central portion of the base is recessed from the peripheral edge, and a tip is formed in a region other than the central portion connected to the rotary tool in the recessed portion. Since the cup-type rotary cutting tool has a much larger tip forming region than the straight-type rotary cutting tool, there is an advantage that the work can be efficiently performed on a wide surface to be ground.

As a conventional example of a cup-shaped rotary cutting tool, there is a rotary cutting tool (rotary grindstone) disclosed in Patent Document 1. In this rotary cutting tool, a portion of the circular substrate (2) having a recess except the recess is molded into an annular flat region, and a metal having a plurality of grindstone pieces (11) formed in this planar region. The annulus plate (8) is fixed. The grindstone piece (11) is formed of diamond abrasive grains or cubic boron nitride, and has an outer grindstone that curves along the outer circumference of the substrate (2) and a longitudinal direction along the central portion of the substrate (2) in the rotational direction. A mixture of curved diameter side grindstones. It is said that the outer grindstone and the inner grindstone are curved in order to improve the processing accuracy of the surface of the building and the like.

Further, Patent Document 2 includes a base metal (21) having a recess formed in a substantially disk-shaped central portion having a mounting hole formed in the center, and a plurality of base metal (21) on the outer peripheral portion of the base metal (21). A rotary cutting tool (cup wheel) in which a small grinding portion (27) is fixed by a screw member is disclosed. Each small grind portion (27) is fixed to a ring-shaped support substrate (27a). If a part of the small grind portion (27) is damaged, only the damaged small grind portion (27) can be replaced.

Japanese Unexamined Patent Publication No. 2014-42980 JP-A-2015-223691

In the rotary cutting tool disclosed in Patent Document 1, the substrate (2) is molded of a resin material in order to emphasize the weight. Similarly, in the rotary cutting tool disclosed in Patent Document 2, the base metal (21) is molded of a resin material.

Therefore, the diameter of the circle connecting the outer peripheral portions of the plurality of outer grindstones in the rotary cutting tool of Patent Document 1 must be larger than the diameter of the substrate (2). The same applies to the rotary cutting tool disclosed in Patent Document 2 (paragraph 0031 of Patent Document 2, etc.). With a rotary cutting tool having such a structure, it is difficult to target a large number of rectangular tiles arranged in a matrix shape, a net shape, or a horse tread shape as a target to be ground.

That is, the rectangular tiles are attached with a uniform width called joints, but since the rotary cutting tool is circular in front view and the outer peripheral portions of the plurality of outer grindstones are larger than the diameter of the substrate (2), the rectangular tiles are attached. When grinding corners, the adjacent rectangular tile may be damaged. At that time, if the rotary cutting tool touches the rectangular tile, sparks will be generated, which is dangerous. Therefore, the rotary cutting tool must be handled with care, which may reduce workability.

Further, as is clear from the disclosure of Patent Documents 1 and 2, in the cup-shaped rotary cutting tool, the central portion of the base metal is recessed from the peripheral edge, and the recessed portion other than the central portion connected to the rotary tool. Since chips are formed in the region, it is difficult to process the base metal. Therefore, it is difficult to reduce the manufacturing cost of the entire rotary cutting tool.

The present invention provides a rotary cutting tool having a structure capable of improving workability without damaging adjacent grinding objects even when the grinding objects are close to each other, such as a rectangular tile. That is the main issue. Other objects of the present invention will become clear from the examples of embodiments described later.

In the rotary cutting tool according to one aspect of the present invention that achieves the above object, a flange-type base metal having a screw hole screwed in the inner wall of the central portion in parallel with the axis to form a perfect circle when viewed from above, and the base metal of the above-mentioned base metal. It has a plurality of grindstone pieces erected from the flange surface to the object to be ground, and the plurality of grindstone pieces are a plurality of first grinding blades arranged concentrically with the outer periphery of the flange surface and the flange. Each of the plurality of first grinding blades includes a plurality of second grinding blades arranged from the substantially outer periphery of the surface toward the axis of the flange, and each of the plurality of first grinding blades has a sharp corner on the inner peripheral side and is on the outer peripheral side. The corners are formed into a blunt shape, and each of the plurality of second grinding blades is a gap between two adjacent first grinding blades and is formed from a curve connecting the inner circumferences of the adjacent first grinding blades. Is formed starting from an outer position, and when the base metal rotates about the axis, a chip region is formed on the flange surface of the base metal, and the outer diameter of the flange surface is the tip region. It is characterized by being larger than the outer diameter.

In the rotary cutting tool of the present invention, the outer diameter of the flange surface of the base metal is larger than the outer diameter of the chip region. Therefore, the situation of contacting the object adjacent to the object to be ground is avoided, and the workability is improved, which is a special effect.

It is a structural explanatory view of the rotary cutting tool of this embodiment, (a) is a rear view, (b) is a cross-sectional view of AA'in (a), and (c) is a front view. (A) to (c) are diagrams showing the progress of rotation of the flange surface. It is explanatory drawing which shows the position of the critical state at the time of the grinding work of a rotary cutting tool. It is a partially enlarged view of FIG. It is a figure which shows the shape and structure example of a joint. (A) and (b) are external perspective views showing a state in which the rotary cutting tool is attached to the rotary tool using a joint from different angles, and (c) is an external front view of the rotary cutting tool. It is explanatory drawing which shows the use state of the rotary tool which fixed the rotary cutting tool and a joint. It is an external front view which shows the deformation example of a rotary cutting tool.

Hereinafter, an example of an embodiment according to one aspect of the present invention will be described. The rotary cutting tool of the present embodiment is a tool for grinding an object to be ground such as tiles and mortar, and is used by being screwed and fixed to the rotary shaft of the rotary tool in the direction opposite to the direction of rotation. .. The rotary tool is, for example, a known hand-held grinder, and a male screw protrudes as a rotary shaft.

In the present specification, for convenience, the rotary tool side to which the rotary tool is attached is the back side or the back side, the object to be ground side is the front part or the front side, and the parts other than the back part and the front part are the side parts and the rotation. The axis that coincides with the central axis of the axis is called the axis, and viewing the front side from the direction parallel to the axis is the top view, and viewing the back side from the direction parallel to the axis is the bottom view or the back view, and the axis. Looking at the side surface from the orthogonal side is called side view.

1A and 1B are structural explanatory views of the rotary cutting tool of the present embodiment, FIG. 1A is a rear view, FIG. 1B is a sectional view taken along the line AA'of FIG. 1A, and FIG. 1C is shown in FIG. Is a front view. 2A to 2C are explanatory views showing a state when the tool is mounted on a rotary tool and rotated.
Referring to FIG. 1, the rotary cutting tool 1 of the present embodiment includes a flange-type base metal 10 forming a perfect circle when viewed from above as a component.

The base metal 10 has a columnar flange portion 11 having a thickness of h2 and an outer diameter of D1 and forming a perfect circle when viewed from above, and a bearing portion 12 integrally molded with the flange portion 11 on the back surface side of the flange portion 11. Consists of including. The base metal 10 is a hard member containing metal particles, and its hardness is Brinell hardness of HBW201 or more and HBW355 or less. This hardness is equal to or higher than that of iron (Fe). The hardness of a general member of a cup-type rotary cutting tool is Brinell hardness HBW137 to HBW170, but in the present embodiment, the hardness is increased to the above-mentioned hardness by performing a heat treatment described later using the same member as a starting material. The reason why the hard member having such hardness is used is to reduce the wear of the base metal 10 when it comes into contact with a hard object to be ground such as a tile.

The front surface of the flange portion 11 is referred to as a flange surface 11a. The flange surface 11a is a flat surface when viewed from the side. Therefore, unlike a general cup-type rotary cutting tool, it is not necessary to form a recess or an inclined surface to form a complicated structure, and the manufacturing process of the base metal 10 is simplified, which is suitable for mass production. Will be.

The bearing portion 12 has a length from the back surface of the flange portion 11 of h1 and an outer diameter of D2 (<D1). It is molded into a shape having a pair of gripping surfaces 122 which are D3 (<D2). The pair of gripping surfaces 122 are formed for gripping with a spanner or the like to facilitate rotation of the base metal 10, that is, for tightening or loosening screws. The central portion 111 of the flange portion 11 centered on the axial center is also the central portion 121 of the bearing portion 12, and a hole 13 having an inner diameter of D4 is formed in parallel with the axial center. That is, the central portions 111 and 121 are open, respectively.

A support ring 14 extending at a predetermined length in parallel with the axis is inserted into the hole 13 on the bearing portion 12 side from slightly inside the opening end to the flange portion 11 side, and the flange portion is inserted from the insertion end portion of the support ring 14. A female screw 111a is threaded on the inner wall of the hole 13 up to the opening end of the central portion 111 of 11. That is, the hole 13 formed in the inner wall of the central portion in parallel with the axis becomes a screw hole. The female screw 111a is formed in a size and shape to be screwed into a male screw protruding from a rotary tool (not shown). From the end of the opening to the end of the support ring 14, the inner diameter is gradually reduced in a tapered shape, which facilitates insertion of the support ring 14 into the hole 13. The outer diameter of the support ring 14 is D5 (> D4), which is larger than the distance from the screw bottom to the screw head of the female screw 111a. The inner diameter of the opening end on the bearing portion 12 side is D6 (<D5).

On the flange surface 11a, three first grinding blades 15a, 15b, 15c and three second grinding blades 15d, 15e, 15f are erected as an example of a grindstone piece at a height h3 from the flange surface 11a, respectively. As a result, a three-dimensional chip region 15 having a height h3 is formed on the flange surface 11a to grind the object to be ground when the base metal 10 rotates.

The first grinding blades 15a, 15b, and 15c each have an arc shape concentric with the outer periphery of the outer periphery of the flange surface 11a, which is slightly inward of the outer periphery of the region obtained by dividing 360 degrees into three equal parts starting from the axis of the central portion 111. The blades are arranged one by one at equal intervals between the adjacent first grinding blades.
Further, in the second grinding blades 15d, 15e, 15f, both ends thereof are along the boundary line of the region where the outer periphery of the flange surface 11a is divided into three equal parts of 360 degrees from the axis of the central portion 111. They are evenly distributed one by one. That is, the second grinding blade 15d has an opening of the central portion 111 with one end at a position on a curve connecting the outer circumferences of the first grinding blades 15a and 15b, which is a gap between two adjacent first grinding blades 15a and 15b. With the position at or near the end as the other end, the surface portion in the direction of rotation forms a convex surface, and the surface portion in the opposite direction forms a concave surface.

The shape of each grinding blade 15a, 15b, 15c, 15d, 15e, 15f having a convex surface and a concave surface as shown in the figure reduces the air resistance of the rotary cutting tool 1 during rotation and cools the space between the grinding blades. This is because it is used as an air passage and a discharge path through which grinding dust or dust passes. That is, when the base metal 10 rotates in the directions of FIGS. 2 (a) to 2 (c) showing the XY coordinate planes (two-dimensional planes) viewed from the front, FIG. 2 (a) showing the state during rotation drive. In), the airflow accompanying the rotation does not occur much. However, as shown by the arrow in FIG. 2 (b) showing the state where the rotation starts to increase, the air flow gradually occurs, and as shown by the arrow in FIG. 2 (c) where the rotation speed further increases, the air flow rotates. It grows in the opposite direction. In the present embodiment, this air flow is guided along the concave surface of the second grinding blades 15d, 15e, 15f to the front ends of the first grinding blades 15a, 15b, 15c without resistance.

Specifically, the front end portion of the first grinding blade 15a when viewed from the rotation direction is formed into a shape in which, for example, the front end portion has an acute angle and the portion close to the outer peripheral edge of the flange portion 11 has an obtuse angle. On the contrary, of the outer end portions (end portions in the direction away from the central portion 111) of the second grinding blade 15d on the rear side when viewed from the rotation direction, the frontmost portion is an obtuse angle and the rearmost end portion is an acute angle when viewed from the rotation direction. It is molded into a shape that becomes. As a result, the air resistance of the grinding blades 15a and 15d during rotation can be suppressed. Further, the grinding blades 15a and 15d are cooled by the air flow without providing a cooling mechanism such as a fan. The same description applies to the first grinding blade 15b and the second grinding blade 15e, and the first grinding blade 15c and the second grinding blade 15f. As a result, the grinding dust or dust in the chip region 15 is smoothly discharged to the outside of the base metal 10 together with the air flow.

Next, a method of manufacturing the rotary cutting tool 1 of the present embodiment will be described. The rotary cutting tool 1 can take various starting materials and a process of processing them depending on the material, shape, arrangement condition, etc. of the object to be ground. In the present embodiment, first, the base metal 10 is made of carbon steel or alloy steel. To make. The manufacturing method may be either molding processing or removal processing of unnecessary portions. A powder metallurgy method can also be used. After that, grinding blades 15a, 15b, 15c, 15d, 15e, and 15f were manufactured by the following steps, and these were fixed to the flange portion 11 of the base metal 10 to be used as a prototype of the rotary cutting tool 1.

First step: The metal powder and the binder powder are mixed to prepare a bond system.
Second step: The diamond superabrasive grains are mixed in the bond system. At that time, each abrasive grain is uniformly mixed so that the diamond superabrasive grains do not gather to form a lump. The mixture thus obtained is referred to as a first mixture.

Third step: For example, the first mixture is put into a carbon mold having high heat conduction efficiency and shaped. Specifically, a predetermined pressure is hardened at a predetermined temperature over a predetermined time (cold working). The predetermined temperature and pressure are temperatures and pressures of 720 degrees Celsius or less, in which the abrasive grains and metal powder do not recrystallize and the crystal structure becomes dense, and the predetermined time is the temperature and pressure of each abrasive grain and metal powder. This is the time immediately before the crystal structure changes. By slowly applying pressure at such a temperature over a predetermined time, there is an effect that work hardening is promoted.

Fourth step: Diamond chips (grinding blades 15a, 15b, 15c, 15d, 15e, 15f) are produced by further applying heat and pressure in a carbon mold and baking. Specifically, a diamond chip having a small residual stress is produced by hot working while applying pressure at a high temperature equal to or higher than the recrystallization temperature of a metal of 900 degrees Celsius to 1200 degrees Celsius. The diamond tip has a flat bottom surface and has the shapes of the grinding blades 15a, 15b, 15c, 15d, 15e, and 15f shown in FIG. 1C when viewed from above. The hardness of the diamond chip thus produced is 50 times or more that of the base metal 10.

Fifth step: The bottom surface of the diamond chip produced in the fourth step is fixed to the flange surface 11a of the base metal 10. For fixing, a thermosetting adhesive or an ultraviolet curable adhesive may be used, or brazing may be used. Since the bottom surface of the diamond chip is flat, the fixing area can be increased, and the diamond chip can be strongly fixed to the flange surface 11a in any manner. Further, although it may be directly fixed to the flat flange surface 11a, a recess having the same shape as the bottom surface of the diamond chip is formed in advance on the flange surface 11a, and the diamond chip is fitted and fixed in this recess. You may do it.

Sixth step: A colorless clear coating agent is applied to the flange portion 11 of the base metal 10 and the surface of the diamond chip, and then dressing is performed. That is, at least the portion of the diamond chip opposite to the bottom surface is polished until the diamond grains are exposed. The purpose of applying the clear coating agent is to prevent surface oxidation of the rotary cutting tool 1, and the reason for making it colorless is to avoid the situation where the color is colored when it comes into contact with a part other than the object to be ground. be.

All diamond chips may have the same shape and size. In this case, one carbon mold used in the second step and the third step is sufficient, which is advantageous in terms of manufacturing cost. Further, the obtuse angle of the front end portion in the rotation direction of the first grinding blades 15a, 15b, 15c may be made larger, or the acute angle portion of the rear end portion may be removed. Further, all the corners may be removed to form an R shape. Further, of the second grinding blades 15d, 15e, 15f, only the inner end portion (the end portion in the direction closer to the central portion 111) may be brought closer to the rotation direction from the position shown in FIG. 1 (c) or the like. In this case, the obtuse angle portion of the outer end portion (the end portion in the direction away from the central portion 111) may be closer to 180 degrees, and the acute angle portion may be closer to 0 degrees.

By arranging the grinding blades 15a, 15b, 15c, 15d, 15e, and 15f as shown in FIGS. 1 (b), (c), and 2, the outer edge of the chip region 15 in the top view is the first grinding blade. It has a first circular shape connecting the convex curved surfaces of 15a, 15b, and 15c and the outer ends of the second grinding blades 15d, 15e, and 15f, and the inner edge of the chip region 15 in the top view is the second grinding blade 15d, It forms a second circle connecting the inner ends of 15e and 15f (the ends near the central portion 111). That is, the chip region 15 is an annular shape obtained by subtracting the second circle from the first circle when viewed from above. However, since the chip region 15 is three-dimensional, in actual grinding work, it is scraped slightly to the outside of the outer edge of the chip region 15. In consideration of this point, the outer diameter of the flange 10 is designed to be larger than the diameter of the outer edge including the outer diameter (= outer edge) of the chip region 15 and the region actually cut.

The gap between the outer diameter of the first circular tip region 15 during rotation and the outer diameter of the flange 10 when viewed from above is called an “offset value”. There is an optimum offset value, and if it is too large, the corners cannot be scraped when the object to be ground is a rectangular tile. On the contrary, if the offset value is too smaller than the optimum value, the base metal 10 will be worn before the respective grinding blades 15a, 15b, 15c, 15d, 15e, 15f in the case of a hard object to be ground such as a tile. , Each grinding blade 15a, 15b, 15c, 15d, 15e, 15f grinds to the adjacent rectangular tile which is not originally the object of grinding.

The optimum offset value is based on the arrangement interval of members other than the work piece, such as rectangular tiles, which exist vertically and horizontally in the vicinity of the work piece, the diameter D of the base metal 10, the degree of wear of the base metal 10, and the like. It is determined.

An example of the optimum value of the offset value will be described. As shown in FIG. 3, for example, the object to be ground is only one rectangular tile 300 shown by a two-dot broken line among the four rectangular tiles 300, 301, 302, and 303, which are fixed with mortar, respectively. do. Each of the rectangular tiles 300, 301, 302, and 303 has the same size, the long side is W1, the short side is W2, and the joint width is M10. FIG. 3 shows a state in which the outer periphery of the base metal 10 is brought to the corner as much as possible with respect to the object to be ground, that is, a critical state of the grinding operation. The flange surface 11a of the base metal 10 is shown by a solid line for convenience in order to show the relative positional relationship with the object to be ground and other parts, but in reality, the rectangular tile 300 and the flange surface 11a face each other.

FIG. 4 is a partially enlarged view of FIG. 3, and the axis is indicated by O. The radius of the outer diameter of the chip region 15 is T, the radius of the circle that is actually ground beyond the outer edge of the chip region 15 is S, the joint width between the rectangular tiles is m (M10 in FIG. 3), and the radius S is the above. Assuming that the length obtained by subtracting the radius T is d and the value obtained by subtracting the radius S from the radius (D / 2) of the flange 10 is f, the optimum value of the offset value shall be a value obtained from the following equation or less. Can be done.
[M ・ (√2)-((√2) -1) ・ D) / 2 + d]

When the values d and f are known, the optimum value can be determined as the total value. Further, when determining the optimum value, the wear coefficient of the base metal 10, particularly the flange 11, and the hardness of the object to be ground are taken into consideration. When a general-purpose rectangular tile 300 attached in a matrix is used as an object to be ground, the offset value is about 1 [mm], but it is desirable that the offset value is not less than 0.3 [mm]. If it is less than 0.3 [mm], the flange portion 11 may be worn before the life of each grinding blade 15a, 15b, 15c, 15d, 15e, 15f, and the members other than the object to be ground may be damaged. be. On the other hand, when the offset value is close to 2 [mm], there is a large amount of uncut portion, and it becomes particularly difficult to cut the corner portion of the rectangular tile.

Next, a mode of attaching the rotary cutting tool 1 to the rotary tool will be described. If the male screw protruding as the rotating shaft of the rotary tool is long enough, insert the male screw into the hole 13 on the bearing portion 12 side of the base metal 10, and while gripping the gripping surface 122 with a spanner or the like. The work can be performed by tightening the base of the male screw until it is accommodated in the support ring 14. The tightening direction is opposite to the rotation direction of the rotary cutting tool 1. However, from the viewpoint of further improving workability during grinding, it is preferable to use a joint.

The joint may have, for example, the shape shown in FIG. In the illustrated example, the joint 20 includes a joint main body portion 21 and a male screw 22 protruding from the joint main body portion 21. The material and manufacturing method are the same as those of the base metal 10.
The joint main body 21 has a female screw having the same pitch and inner diameter as the male screw 22 formed therein, and has a pair of grip surfaces 23 having the same purpose as the grip surface 122 formed on the bearing portion 12 of the base metal 10 on the surface thereof. It has a substantially cylindrical shape formed, and its outer diameter is the same as or slightly smaller than the inner diameter of the support ring 14. The male screw 22 has a shape suitable for the male screw of the rotary tool and the female screw 111a screwed into the base 10 of the rotary cutting tool 1, and its tip is inserted from the opening edge of the bearing portion 12 of the base 10. , It is tightened with a spanner or the like using the gripping surface 23.
The joint 20 is made of the same material as the base metal 10 and can be manufactured with substantially the same hardness as the base metal 10. Therefore, the joint 20 can be used as a part of the base metal 10 or the rotary cutting tool 1.

6 (a) and 6 (b) are external perspective views showing the state in which the rotary cutting tool 1 is attached to the rotary tool using the joint 20 from different angles, and FIG. 6 (c) shows the rotary cutting tool 1 It is an external front view seen from the front. The rotary tool 30 includes a hollow gripping housing 31 having a shape and size that can be gripped by an operator with one hand. A rotation drive mechanism and a drive transmission mechanism (not shown) are housed in the hollow gripping housing 31, and a cutting tool mounting housing is attached to the tip thereof.

The cutting tool mounting housing has a pair of inclined surfaces 31 and 33 whose facing distance becomes smaller toward the tip, and one of the inclined surfaces 31 has a higher height from the inclined surface 31 toward the tip. It is a housing in which a substantially cylindrical portion 32 is formed. Although not shown, inside the columnar portion 32, the above-mentioned male screw to which the rotational force applied by the drive transmission mechanism is applied has a predetermined angle with respect to the hollow gripping housing 31 (the rotation axis of the drive transmission mechanism inside thereof). For example, the male screw protrudes at approximately 90 degrees with respect to the rotation axis in the hollow grip housing 31, the male screw is screwed into the female screw of the joint main body 21, and the male screw 22 protruding from the joint main body 21 rotates. It is screwed into the female screw 111a of the bearing portion 12 of the cutting tool 1.

FIG. 7 is an explanatory diagram showing a usage state of the rotary tool 30 in which the rotary cutting tool 1 and the joint 20 are fixed. The object to be ground is only one rectangular tile among the plurality of tiles arranged in the matrix shown in FIG. If you cut other rectangular tiles, it will take a lot of labor to repair them, so it requires skill. Further, since each rectangular tile is fixed with mortar, it is higher than the joint, the joint has a narrow width, and the tip region 15 of the rotary cutting tool 1 is also three-dimensional, which is general. Is difficult to work with.

However, in the rotary cutting tool 1 of the present embodiment, the outer diameter of the flange 11 of the base metal 10 is larger than the outer diameter of the chip region 15 (outer diameter at the time of rotation), and the space between the outer edge of the chip region 15 and the flange 11 Since the offset value of is designed to be the optimum value, it is possible to easily avoid the situation where the adjacent rectangular tile is cut. Since the worker does not need to be aware of the above situation, workability can be improved. Further, since the hollow gripping housing 31 of the rotary tool 30 has a predetermined angle (for example, about 90 degrees) with the rotation axis of the rotary cutting tool 1, there is an advantage that the work becomes easier.

[Modification example]
The present invention can be implemented in various modifications other than the shape and structure described in the present embodiment. For example, in the present embodiment, as shown in FIG. 1 (c) and the like, the second grinding blades 15d, 15e, 15f are described on the premise that they have the same shape and size as the first grinding blades 15a, 15b, 15c. However, the second grinding blades 15d, 15e, 15f may be smaller or larger than the first grinding blades 15a, 15b, 15c.
Further, the rotary cutting tool 1'exemplified in FIG. 8 may be used. In the rotary cutting tool 1'shown in FIG. 8, the second grinding blades 15'd, 15'e, and 15'f have a substantially "dogleg" shape when viewed from above, that is, have a convex surface in the rotation direction, and the opposite direction of the convex surface. Has a concave shape. This makes grinding of the object to be ground more efficient. Further, in the rotary cutting tool 1'shown in FIG. 8, the first grinding blades 15'a, 15'b, 15'c have at least the front end portion in the rotation direction of the second grinding blades 15'd, 15'e, 15'. The shape is almost parallel to the surface opposite to the rotation direction of'f. As a result, the grinding dust or dust in the chip region 15 can be more smoothly discharged to the outside of the base metal 10.

Further, in the present embodiment, an example in which the first grinding blades 15a, 15b, 15c and the second grinding blades 15d, 15e, 15f are three, respectively, has been described, but two or four or more may be used. There is no limit to the number of airflows generated during rotation and the number of grinding chips or dust in the chip region 15 as long as they can be discharged to the outside more smoothly and in large quantities.

Further, the shape and structure of the rotary tool 30 shown in FIGS. 6 (a) to 6 (c) and FIG. 7 are not limited to the examples shown in these figures, and an existing grinder or the like may be used. can. Further, a dustproof hood may be added to the rotary tool 30 to prevent dust generated during work from being given to the operator.

Claims (6)

A flange-type base metal with a screw hole threaded parallel to the axis in the inner wall of the central part to form a perfect circle when viewed from above, and a plurality of grindstone pieces erected from the flange surface of the base metal to the object to be ground. The plurality of grindstone pieces are arranged from the substantially outer periphery of the flange surface to the axial center of the flange and the plurality of first grinding blades arranged concentrically with the outer periphery of the flange surface. Including multiple second grinding blades
Each of the plurality of first grinding blades is formed into a shape in which the corner portion on the inner peripheral side has an acute angle and the corner portion on the outer peripheral side has an obtuse angle.
Each of the plurality of second grinding blades is formed from a position outside the curve connecting the inner circumferences of the adjacent first grinding blades in the gap between the two adjacent first grinding blades. ,
When the base metal rotates about the axis, a chip region is formed on the flange surface of the base metal, and the outer diameter of the flange surface is larger than the outer diameter of the chip region.
Rotating blade. It is determined that the offset value, which is the difference between the outer diameter of the chip region and the outer diameter of the flange surface during rotation, is determined based on the arrangement interval of members other than the object to be ground existing in the vicinity of the object to be ground. Characteristic,
The rotary cutting tool according to claim 1. The plurality of first grinding blades and the plurality of second grinding blades each have a convex surface that guides an air flow generated during rotation to the outside of the base metal.
The rotary cutting tool according to claim 1 or 2. The hardness of the base metal is Brinell hardness of HBW200 or more and less than 355, and the hardness of the plurality of grindstone pieces is higher than that of the base metal.
The rotary cutting tool according to any one of claims 1 to 3. A bearing portion having a screw hole screwed in a central shaft thereof and a gripping surface formed on the surface thereof is integrally formed with the base metal on the back surface side of the base metal.
The rotary cutting tool according to any one of claims 1 to 4. The bearing portion is characterized in that it is joined to a rotary tool serving as a rotation drive source directly or via a joint having a male screw and a female screw that fit into the screw hole.
The rotary cutting tool according to claim 5.

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