Rotary abrasive material

Abstract

A first member has a base plate 11 and an abrasive sheet installation portion 12 where an abrasive sheet is fixed. The base plate or the abrasive sheet installation portion is provided with an air-introducing portion 15 as a space penetrating from the back face side to the front face side of the base plate or the abrasive sheet installation portion, and an airflow passes from the back face side to the front face side as a rotary abrasive material rotates. When the first member is used as a single unit, overheating is prevented and swarf can be removed when the rotation of a projection portion as the abrasive sheet installation portion 12 generates an airflow flowing through the air-introducing portion 15. Further, when a second member is provided such that its axial position is adjustable relative to the first member, an abrasive sheet of the second member can project and retract against the first member, so that, depending on processing required, grinding work can be performed by easily switching abrasive sheets to be used.

Description

FIELD OF THE INVENTION

The present invention relates to a rotary abrasive material to be attached to a rotating tool in use.

BACKGROUND ART

Conventionally, rotary abrasive materials of disk-like objects, which can grind an object to be ground after being attached to a rotating shaft of the rotating tool such as a grinder and rotated, have been used. These rotary abrasive materials are, for example, for disk-grinders or for buffing disks.

In addition, like a “grinding disk” described in Japanese Published Unexamined Patent Application No. H09-174444, a rotary abrasive material where an abrasive sheet such as sandpaper is radially arranged on the front face of a disk-like base plate has been known.

In the rotary abrasive material of this type, frictional heat is generated in use between the object to be ground and the abrasive sheet, and degradation of the abrasive sheet and deterioration of the object is likely to occur because of the frictional heat.

In addition, when using a rotary abrasive material, a rotary abrasive material with large-grit sandpaper for roughing and a rotary abrasive material with fine-grit sandpaper for finishing are selectively used, and the rotary abrasive material is alternatively attached to the rotating tool in such performances, orrotating tools attached with different rotary abrasive materials are separately prepared.

In view of the above-described problems, it is a first object of the present invention to provide a rotary abrasive material which can prevent frictional heat generated between an object to be ground and abrasive sheet.

Also, it is a second object to provide a rotary abrasive material, wherein a large-grit abrasive sheet and a fine-grit abrasive sheet can be switched without replacing the rotary abrasive material itself.

DISCLOSURE OF THE INVENTION

In order to solve the above-described objects, a first aspect of the invention provides a rotary abrasive material, which is a disk-like object with an abrasive sheet 14 arranged on its front face and can grind an object to be ground by being attached to a rotating tool G, wherein the rotary abrasive material 10 hasabase plate11 andan abrasive sheet installation portion 12; the base plate 11 being like a disk in a plan view and attachable to a rotating shaft S of the rotating tool G in the center thereof; the abrasive sheet installation portion 12 being provided extending in a radial outward direction of the base plate 11 and attached with the abrasive sheet 14 to the-front face side thereof, and-in the base plate 11 or abrasive sheet installation portion 12 is provided an air-introducing portion 15 which is a space penetrating from the back face side to the front face side and through which an airflow passes from the back face side to the front face side as the rotary abrasive material 10 rotates.

A second aspect of the present invention provides the rotary abrasive material according to the first aspect, wherein the abrasive sheet installation portion 12 is a projection portion 12 provided in plurality so as to project in the radial outward direction of the base plate 11, wherein the air-introducing portion 15 is a space existing between the projection portions 12, and the abrasive sheet 14 is attached to the projection portions 12.

A third aspect of the present invention provides the rotary abrasive material according to the second aspect, wherein an outer circumferential connecting portion 16 is formed so as to connect outer circumferential portions 12c of the respective projection portion 12 to each other, whereby the air-introducing portion 15 is surrounded by the base plate 11, projection portions 1, and outer circumferential connecting portion 16.

A fourth aspect of the present invention provides a rotary abrasive material, which is a disk-like object with abrasive sheet 14 arranged on its front face and can grind an object to be ground by being attached to a rotating tool G, wherein the rotary abrasive material 10 has a base plate 11 that is like a disk in a plan view and attachable to a rotating shaft S of the rotating tool G in the center thereof; at least part of the front face side of the base plate 11 being attached with the abrasive sheet 14, and in the base plate 11 is provided an air-introducing portion 15 which is a space penetrating from the back face side to the front face side and through which an airflow passes from the back face side to the front face side as the rotary abrasive material 10 rotates.

A fifth aspect of the present invention provides a rotary abrasive material 10, which is a disk-like object with abrasive sheets 14, 23 arranged on its front face and can grind an object to be ground by being attached to a rotating tool G, wherein the rotary abrasive material 10 comprises a first member 1, a second member 2, and an attachment position adjusting means 25, wherein the first member 1 having a base plate 11 and p projection portion 12; the base plate 11 being a disk in a plan view and attachable to a rotating shaft S of the rotating tool G in the center thereof; the projection portion 12 being provided in plurality so as to project in the radial outward direction of the base plate 11 and having an abrasive sheet inserting space 15 between the projection portions 12; the abrasive sheet 14 being attached to a one-side surface of the projection portion 12, and the second member 2 has a base plate 21; the base plate 21 being like a disk in a plan view and attachable to a rotating shaft S of the rotating tool G in the center thereof; the abrasive materials 23 being disposed on a one-side face of the base plate 21 and at a position, in a plan view, corresponding to the abrasive sheet inserting space 15 of the first member 1, and the attachment position adjusting means 25 is a means for adjusting a relation of position in the axial direction in combining the first member 1 and second member 2, whereby the abrasive materials 14 of the first member 1 and abrasive materials 23 of the second member 2 alternatively disposed by combining the first member 1 and second member 2 so as to make the centers of the respective base plates 11 and 21 meet, wherein the abrasive sheets 23 of the second member 2 can project and retract against the first member 1.

A sixth aspect of the present invention provides the rotary abrasive material according to any of the second, third, and fifth aspects, wherein the abrasive sheet 14, 23 is disposed inclined against a rotating direction of the rotary abrasive material 10.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a method for attachment, to a rotating tool, a rotary abrasive material according to a first embodiment carried out in the present invention.

FIG. 2(A) is a perspective view showing, in the rotary abrasive material of the first embodiment, a condition where a second member remains retracted against a first member, and

FIG. 2(B) is an explanatory drawing of a side view showing a main part in the same condition.

FIG. 3(A) is a perspective view showing, in the rotary abrasive material of the first embodiment, a condition where a second member projects against a first member, and FIG. 3(B) is an explanatory drawing of a side view showing a main part in the same condition.

FIG. 4 is aperspective view showing, in the rotary abrasive material of the first embodiment, a method for combining the first member, second member, and connection member.

FIG. 5(A) is a plan view showing, in the rotary abrasive material of the first embodiment, a connection member, and FIG. 5(B) is a front view of the same, and FIG. 5(C) is a bottom view of the same.

FIG. 6 is respectively an explanatory drawing of a plan view showing a condition where, in the rotary abrasive material of the first embodiment, the first member is attached to the connection member, wherein FIG. 6(A) shows a case where these are engaged and FIG. 6(B) shows a case where the first member is disengaged.

FIG. 7 is a plan view showing, in the rotary abrasive material of the first embodiment, a base plate and a projection portion of the first member, wherein dotted line parts in the drawing show an outer circumferential connecting member.

FIG. 8(A) is an explanatory drawing of a side view showing, in the rotary abrasive material of the first embodiment, a main part of the first member, and FIGS. 8(B) and 8(C) are explanatory drawings of side views showing main parts in other embodiments.

FIG. 9(A) is a perspective view showing a rotary abrasive material according to another embodiment of the present invention, and FIG. 9(B) is an explanatory drawing of a side view showing a main part of the same.

FIG. 10 is a perspective view showing a rotary abrasive material according to further embodiment of the present invention.

FIG. 11 is a perspective view from the back face side of a rotary abrasive material according to a second embodiment carried out in the present invention.

FIG. 12 is a perspective view from the front face side of the rotary abrasive material according to the second embodiment carried out in the present invention.

BEST MODE TO CARRY OUT THE INVENTION

First, based on the drawings, a description will be given of a rotary abrasive material according to a first embodiment carried out in the present invention. FIG. 1 is a perspective view showing a method for attaching the rotary abrasive material of the present embodiment to a rotating tool, and FIGS. 2 and FIGS. 3 are perspective views showing the rotary abrasive material of the present invention. Here, in the description of the present invention, a side of the rotary abrasive material (including afirstmember, secondmember, etc.) where an abrasive sheet is provided is referred to as a front side, and its opposite side is referred to as a rear side.

A rotary abrasive material 10 according to the present invention is, as shown in FIG. 1, used while being attached to a rotating shaft S of the rotating tool G such as a grinder. A basic structure of this rotary abrasive material 10, being same as a conventional rotary abrasive material, is a disk-like object by attaching an abrasive sheet such as sandpaper to the front face of a base plate rotated by power transmitted from the rotating shaft S of the rotating tool G.

An attachment of the rotary abrasive material 10 to the rotating tool G is done by inserting the rotating shaft S of the rotating tool G through an inserting hole 25k provided at the center of the rotary abrasive material 10 (in the present embodiment, at the center of a connection member 25) and screwing a lock nut N into the rotating shaft S.

An external appearance of the rotary abrasive material 10 of the present embodiment is what FIGS. 2 and FIGS. 3 show, which is provided by combining two types of members 1 and 2 in the axial direction (direction of the rotation shaft S) into one unit, as shown in FIG. 4. Hereinafter, a description will be given while referring to these members as a first member 1 and a second member 2, respectively.

For the first member 1, as shown in FIG. 4 and FIG. 7, a synthetic resin base plate 11 and a projection portion 12 are provided.

The base plate 11 in the present embodiment is annular in appearance. In the central part of this base plate 11, a fitting hole 13 to accept a connection member 25 is provided. Here, the connection member 25 to be attached to this fitting hole 13 is attached to the rotating shaft S of the rotating tool G to transmit power from the rotating tool G to the first member 1.

The projection portion 12 as an abrasive sheet installation portion is integrally provided with the base plate 11 in a radical outward direction of the base plate 11, and at one-side surface thereof (the front face, the downward direction in FIG. 4,) an abrasive sheet 14 is adhered.

The section between the projection portions 12 is a space, and this space is an air-introducing portion 15, serving as an abrasive sheet inserting space 15 too. Depending on the usage of the first member 1, this space differently functions as an air-introducing portion 15 and as an abrasive sheet inserting space 15, and the designations are selected depending on its effect in the following.

The abrasive sheet 14 attached to the projection portion 12 is, same as sandpaper, a sheet made of paper, fabric or the like whose one-side face has been coated with abrasive grains such as diamond grains.

In the present embodiment, the abrasive sheet 14 cut in a rectangular form is arranged on the projection portion 12 partially overlapped in the circumferential direction with the side coated with abrasive grains coming front, and fixed by glue or the like. Since the abrasive sheets 14 are arranged on the front face of the projection portion 12 in such a manner as in the above, the abrasive sheets 14 are inclined in a down-rearward direction of the illustration against a rotating direction R of the first member 1, as shown in FIG. 8(A).

The projection portion 12 is formed with an angle against the base plate 11 in a side view. Concretely, as shown in FIG. 8(A), the projection portion 12 is formed so as to incline, following the rotating direction R of the first member 1, upward in the illustration. Since an end face 12a of the front end side and an end face 12b of the rear end side concerning the rotating direction R have been chamfered, in addition to an inclined arrangement of the abrasive sheet 14, the air-introducing portion 15 is a smoothly inclined space without a projection against the rotating direction R.

As a result of such a configuration of the air-introducing portion 15, when the first member 1 is attached as a single unit to the rotary tool G for use, with a rotation of the first member 1, the projection portion 12 guides air existing in the air-introducing portion 15 in a direction from the back side to the front side of the first member (a downward direction in FIG. 8(A)). And an airflow F thus guided passes through the air-introducing portion 15. Therefore, while the first member 1 rotates, this airflow F is always generated and forces away of frictional heat generated between an object to be ground and the abrasive sheets 14, whereby side effects in the conventional art such as degradation of the abrasive sheet 14 and deterioration of the object caused by the frictional heat can be prevented. Additionally, swarf caused by grinding can be removed by this airflow F too.

Herein, in terms of the above effect, as a result of experiments of grinding a ten-square-centimeter steel plate for three minutes, which were performed by the applicant under identical conditions, the surface temperature of the steel plate rose to 80° C. when a conventional rotary abrasive material was used, whereas it rose only to 60° C. when the first member 1 of the present embodiment was used. Consequently, it is confirmed that the cooling effect by the airflow F was achieved effectively.

Here, for simplification of the structure, although the effect to guide air as described above lowers, the projection portion 12 may be formed parallel to the base plate 11, as shown in FIG. 8(B), or may be formed in a triangular form with a horizontal front face in a side view, as shown in FIG. 8(C).

Besides the above, the configuration of the projection portion 12 in a plan view is formed such that, as shown in FIG. 7, the front-end-side end face 12a is along the radial direction, and the rear-end-side end face 12b heads rearward with an angle against the rotating direction R as it goes outward in the radial direction. Owing to the inclination of the projection portion 12 in a side view as described above and such configuration of the same in a plan view, the projection portion 12 functions as a blade in the fan, efficiently guiding air existing in the air-introducing portions 15 to generate an airflow F.

As shown in FIGS. 9, when a current plate 17 is formed in a manner projecting along an approximately circumferential direction of the back face side of the projection portion 12, and an air introducing projection 18 is formed at the back face side of the front-end-side end face 12a (upper side in FIG. 9(B)) in a manner projecting forward against the rotating direction R, air can be guided more efficiently to the air-introducing portion 15 to generate the airflow F.

Also, as shown in FIG. 10, while forming the above-mentioned current plate 17, a slope 19 is formed at a tip part in the radial direction of the projection portion 12 to diminish the front-end-side end face 12a, whereby the first member 1 can be reduced in rotational resistance to generate the airflow F much more efficiently.

As shown by dotted lines in FIG. 7, an outer circumferential connecting portion 16 may be formed in a manner connecting outer circumferential portions 12c of the respective projection portions 12 to each other so that the air-introducing portion 15 is surrounded by the base plate 11, projection portion 12, and outer circumferential connecting portion 16. Furthermore, as in a second embodiment (see FIG. 11 and FIG. 12) a base plate 11 into which the base plate 11, projection portions 12, and outer circumferential connecting portion 16 of FIG. 7 have been integrated may be formed, and a hole-like air-introducing portion 15 may be provided in the base plate 11. In this case, the base plate I1 of the first embodiment corresponds to a central part 11x of the base plate 11 in the second embodiment, while the projection portion 12 of the first embodiment corresponds to a circumferential portion lly of the base plate 11 in the second embodiment.

Thus far, a description has been given concerning a case where the first member 1 is attached as a single unit to the rotating tool G for use. In the following, a description will be given concerning a case where the first member 1 and second member 2 are combined for use.

In the present embodiment, in either case where the first member 1 is attached as a single unit to a rotating tool G for use, or where the first member I and second member 2 are combined for use, a connection member 25 is sure to be used, and power from the rotating tool G is transmitted to the respective members 1 and 2 via this connection member 25. Details of the configuration and function of this connection member 25 will be described later.

A basic form of the second member 2 is the same as that of the first member 1, but the base plate 21 is formed in a flat-plate form, as shown in FIG. 4.

Like the first member 1, a fitting hole 22 to accept the connection member 25 is provided in the central part of the base plate 21.

And, in a plan view, at a position corresponding to the abrasive sheet inserting space 15, which is a space between the projection portions 12 of the first member 1, an abrasive sheet 23 is arranged on the base plate 21 with the same inclination as that of the abrasive sheet 14 of the first member 1. In the present embodiment, an end portion of the abrasive sheet 23 is inserted in the base plate 21 where a notch has been formed in the radial direction before fixing the sheet by an adhesive or the like.

The abrasive sheet 23 used on the second member 2 in the present embodiment is a fine-grit abrasive sheet with finer abrasive grains than those for the abrasive sheet 14 used on the first member 1. However, the combination of the respective abrasive sheets 14, 23 is not limited hereto, and a large-grit abrasive sheet may be used on the second member 2 contrary to the above. Needless to say, an abrasive sheet with an identical roughness may be used.

And, a connection member 25 is attached to the fitting hole 22 of the base plate 21 as an attachment position adjusting means.

The connection member 25 is cylindrical as shown in FIG. 4 and FIGS. 5, and inside of which is provided with an inserting hole 25k to pass the rotating shaft S of the rotating tool G in the axial direction. Also, brim-like projections 25a, 25d, 25g, 25m are provided on its outside surface. Here, the projections 25a, 25d, 25g are not provided across the whole circumference in the circumferential direction of the connection member 25, and the circumference is partially notched as notches 25b, 25e, 25h for attaching the base plate 21 and the base plate 11 of the first member 1. And, the notches 25b, 25e, 25h are formed at point-symmetric positions as shown in FIGS. 5(A) and 5(C).

By disposing the respective base plates 11, 21 at engaging grooves 25c, 25f, 25i formed between the projections 25a, 25d, 25g, 25m, the connection member 25 and the second member 2 as well as the first member 1 are respectively connected. At one-side terminal-end portions of the projections 25a, 25d, 25g of the connection member 25, stoppers 25p, 25q, 25r are provided in a manner blocking the engaging grooves 25c, 25f, 25i.

Herein, an attachment of the connection member 25 to the first member 1 is performed by disposing the base plate 11 of the first member 1 at the engaging groove 25f formed on the side face of the connection member 25.

Concretely, a projection 11a protruding into a fitting hole 13 from the base plate 11 is disposed at the engaging groove 25f by passing the same through the notch portion 25e formed by notching the projection 25d on the side face of the connection member 25, and then the base plate 11 is turned toward the connection member 25 until the projection lha is brought into contact with the stopper 25r and fixed thereto.

On the other hand, an attachment of the connection member 25 to the second member 2 is also basically same as the case of the first member 1. In this case, however, the second member 2 can be axially changed in its attachment position in two stages for a near side and for a deep side with reference to an end-face side (upper end face of FIG. 5(B)) of the connection member 25. When the second member 2 is disposed at the near side, the projection 25a, notch portion 25b, near-side engaging groove 25c, and stopper 25p that have been formed on the connection member 25 function. When the second member 2 is disposed at the deep side, the projection 25g, notch 25h, deep-side engaging groove 25i, and stopper 25q that have been formed on the connection member 25 function.

Concretely, a projection 21a protruding into a fitting hole 22 from the base plate 21 is disposed at the near-side engaging groove 25c by passing the same through the notch portion 25b formed by notching the projection 25a on the side face of the connection member 25, and then the base plate 21 is turned toward the connection member 25 until the projection 21a is brought into contact with the stopper 25r, whereby the second member 2 is fixed to the near side.

Also, as similarly disposed at the deep-side engaging groove 25i by passing the same through the notch portion 25h formed by notching the projection 25g, the base plate 21 is turned toward the connection member 25 until the projection 21a is brought into contact with the stopper 25q, whereby the second member 2 is fixed to the deep side.

Herein, the respective notch portions 25b, 25h are formed with dislocation of a predetermined angle in a plan view. Accordingly, when the first member 1 disposed at the near-side engaging groove 25c is shifted into the deep-side engaging groove 25i, simply the projection 21a of the second member 2 is turned in the circumferential direction so as to meet the same with the notch portion 25h, no special operation required.

A dropout prevention measure is provided between the connection member 25 and respective members 1, 2. Herein, a description will be given as exemplifying a case where the base plate 11 of the first member I is disposed at the engaging groove 25f of the connection member 25.

For the base plate 11 of the first member 1, the projection 11a corresponding to the notch portion 25e of the connection member 25 is formed in a manner projecting into the fitting hole 13, and a stopper notch 11b is formed at an approximately middle portion of this projection 11a. Meanwhile, concerning the connection member 25, a stopper projection 25n is as well formed at a position corresponding to this stopper notch 11b.

This stopper projection 25n serves as a dropout prevention means, whereby dropout of the first member 1 in the axial direction can be prevented.

As shown in FIG. 6(A), when the first member 1 is to be engaged with the connection member 25, the stopper notch 11b of the first member 1 is brought to the position of the stopper projection 25n of the connection member 25, the projection 11a is brought into contact with a projection 25m, and in this condition, the first member 1 is, while being rotated in the direction of arrow F of FIG. 6(A), fitted until the same is brought into contact with the stopper 25r, which is the terminal end of the engaging groove 25f, thus the first member 1 and connection member 25 can be engaged.

A grinding operation is performed by engaging the first member 1 with the connection member 25 as described above and then by attaching the connection member 25 to the rotating tool G. In case the rotating tool G suddenly stops because of, for example, an interruption of the power source with the first member 1 being in contact with an object to be ground in the grinding operation, as shown in FIG. 6(B), only the first member 1 relatively turns in the direction of arrow S of its original movement according to the law of inertia. Thus, only the first member 1 turns in a direction (direction of arrow S) to release an engagement with the connection member 25. In such a manner, the projection 11a separates from one stopper 25r where the same has originally been in contact and hits the other stopper 25r, stopping its rotation.

In order to have the stopper notch 11b of the first member 1 and the stopper projection 25n of the connection member 25 at slightly dislocated position in this condition as shown in FIG. 6(B), the respective positions are set in advance. As a result of this relation of in position, the stopper projection 25n functions as a dropout prevention means.

And, as shown in FIG. 6(A), when the first member 1 and connection member 25 are to be engaged, positions of both members are set in advance so that the stopper notch 11b and stopper projection 25n can be met and engaged.

Although, a description in the above has been given as raising an example of the first member 1, the same applies to the second member 2, and consequently, the same effect as the above is provided even when the first member 1 and second member 2 are simultaneously attached to the connection member 25.

As described in the foregoing, by disposing the base plate 21 of the first member 2 selectively at either two engaging grooves 25c, 25i formed on the side face of the connection member 25 as an engaging groove, the axial position of the second member 2 against the first member 1 is adjustable in two stages. Thereby, the abrasive sheet 23 of the second member 2 can project and retract between the abrasive sheets 14 of the first member 1.

Accordingly, when the projection 11a of the first member 1 is disposed at the near-side engaging groove 25c of the connection member 25, the abrasive sheet 23 of the second member 2 remains retracted against the abrasive sheets 14 of the first member 1, as shown in FIGS. 2. Since only the abrasive sheets 14 appear on the front side, grinding work (roughing) can be performed by the large-grit abrasive sheets 14 in this case of the present embodiment.

When the projection 11a of the first member 1 is disposed at the deep-side engaging groove 25i of the second member 2, the abrasive sheets 23 of the second member 2 project against the abrasive sheets 14 of the first member 1 and cover the same, as shown in FIGS. 3. Therefore, in this case of the present embodiment, grinding work (finishing) can be performed by the fine-grit abrasive sheet 23.

The position of the second member 2 against the first member 1 can be switched as described above by selecting an engaging groove from the engaging grooves 25c, 25i of the connection member 25, and the switching is also easily performed by turning the second member 2 against the connection member 25.

Accordingly, it is not necessary to replace a rotary abrasive material itself at the rotating tool G or to selectively use a rotating tool G with a different rotary abrasive material attached thereto in view of the processing as in the conventional art, whereby switching of grinding can be easily performed.

The present invention is not limited to the embodiments as described above and can be performed in various modifications.

For example, in the case of the first embodiment, the space between the projection portions 12 of the first member 1 functions as an air-introducing portion 15 when the first member 1 is used as a single unit, and when used in combination with the second member 2, the space does as a grinding sheet inserting space 15 to accept the abrasive sheet 23 of the second member 2. However, a notch may be formed on the base plate 21 of the second member 2 at the position corresponding to the grinding sheet inserting space 15 of the first member 1, or the base plate 21 may have a meshed structure so that an airflow can pass through the grinding sheet inserting space 15. Owing to this, even when the first member 1 and second member 2 are used in combination, overheating can be prevented and swarf can be removed.

Also, by increasing the number of engaging grooves formed on the outside surface of the connection member 25, position switching between the first member 1 and second member 2, which is in two stages in the first embodiment, may be made adjustable in three stages or more, so that the two types of abrasive sheets can be simultaneously used for processing.

Next, a description will be given while raising a rotary abrasive material against the second embodiment. FIG. 11 and FIG. 12 are perspective views showing a rotary abrasive material of the present embodiment. Here, for the rotary abrasive material according to the present embodiment as well, a description will be given while using numerals identical to those of the first embodiment for parts except for ones that need to be particularly mentioned.

The rotary abrasive material according to the present embodiment shows a modification where, in the first embodiment, the first member 1 is used as a single unit.

For the rotary abrasive material according to the present embodiment as well, a base plate 11 is provided. This base plate 11 has, as shown in FIG. 11, an annular external appearance and includes the projection portion 12 of the first embodiment 1. In the central part of this base plate 11, similar to the first embodiment, a fitting hole 13 to accept a connection member 25 is provided.

Abrasive sheet 14 same as those of the first embodiment is adhered to a one-side surface (front surface) of the base plate 11. Concretely, as shown in FIG. 12, the abrasive sheet 14 is attached not to a central part 11X of the base plate 11 but to a circumferential part 11y.

An air-introducing portion 15 of the present embodiment is composed of a through hole 15a penetrating from the front face side to the back face side in the central part 11x of the base plate 11 as shown in FIG. 12, and an air-taking groove 15b formed from the central part lix to the circumferential part 11y on the back face side of the base plate 11, communicating with the through hole 15a, as shown in FIG. 11.

The through hole 15a, as shown by dotted lines in FIG. 12, is formed with an inclination to the side of a rotating direction R of the rotary abrasive material as heading from the front face side to the back face side. And, the air-taking groove 15b has a configuration which is curved from the through hole 15a positioned in the central part 11x of the base plate 11 to the radial outward direction of the base plate 11 and to the rotating direction R of the rotary abrasive material, and, in addition, whose width is gradually widened toward the radial outward direction. Also, on the forward side in the rotating direction R beyond the air-taking groove 15b, a slope 11z is formed by cutting the side surface of the base plate 11 as shown in FIG. 11, therefore, air can be smoothly guided to the air-introducing portion 15 as the rotary abrasive material rotates.

By forming the air-introducing portion 15 and slope 11z in the form as described above, as the rotary abrasive material rotates, air is guided into the through hole 15a through the slope 11z and air-taking groove 15b. And, the airflow thus guided passes through the through hole 15a and flows to the front face side of the base plate 11. Therefore, as the rotary abrasive material rotates, like the first embodiment, this airflow is always generated and forces away of frictional heat generated between an object to be ground and the abrasive sheet 14, whereby side effects such as degradation of the abrasive sheet and deterioration of the object caused by the frictional heat can be prevented. In addition, swarf caused by grinding can also be removed by this airflow.

In the present embodiment, a form where the through holes 15a are formed in the central part 11x of the base plate 11 is shown, but the present invention is not limited hereto. For example, the through holes 15a may be formed in the circumferential part 11y so that air flows from the sections between the abrasive sheets 14. Also, air-introducing portions 15 and through holes 15a in the second embodiment may be provided for the projection portions 12 in the first embodiment, and the present invention can be performed in other various forms.

Herein, trial manufacturing of a rotary abrasive material according to the second embodiment and a comparison test of the same performed with a conventional rotary abrasive material will be described.

This comparison test was performed, by use of a stainless steel plate (SUS304) as an object to be ground, by attaching the respective rotary abrasive materials to a disc grinder, performing grinding at a rotating speed of 11000 min⁻¹, and measuring a ground amount of the object to be ground and a reduced weight amount (wheel loss) of the rotary abrasive material every three minutes, for 30 minute in total. In what were used as rotary abrasive material, 80 abrasive sheets whose count is 60 have been disposed per rotary abrasive material.

The results are as in Table 1, wherein the rotary abrasive material according to the present invention could grind away the object to be ground more than the conventional rotary abrasive material. Consequently, it is clear that a grinding operation can be more efficiently performed while removing frictional heat by airflow flowing from the front-surface side of the rotary abrasive material.

	TABLE 1
	Elapse of
	time (min.)	3	6	9	12	15	18	21	24	27	30	Total
Conventional	Ground	13.4	7.8	6.7	4.3	3.9	4.6	4.0	4.0	4.0	4.0	56.7
product	amount (g)
	Wheel loss	0.9	0.1	0.3	0.0	0.2	0.3	0.3	0.3	0.3	0.3	3.0
	(g)
Trial	Ground	16.1	10.0	7.4	4.6	5.4	5.6	4.3	4.7	6.3	11.8	76.2
product	amount (g)
	Wheel loss	0.9	0.5	0.4	0.3	0.3	0.1	0.1	0.1	1.0	0.5	4.2
	(g)

The present invention has the following advantageous effects.

According to the first or fourth aspect of the present invention, as the rotary abrasive material rotates, an airflow passing through the air-introducing portion is always generated. Owing to this, the airflow forces away of frictional heat generated between an object to be ground and abrasive sheet, whereby side effects such as degradation of the abrasive sheet and deterioration of the object caused by the frictional heat can be prevented.

According to the second or third aspect of the present invention, as the rotary abrasive material rotates, the projection guide air existing in the air-introducing portion to one side, whereby an airflow is generated. And, this airflow always passes through the air-introducing portion as the rotary abrasive material rotates. Therefore, this air flow forces away of frictional heat generated between an object to be ground and abrasive sheet, whereby side effects such as degradation of the abrasive sheet and deterioration of the object caused by the frictional heat can be prevented.

According to the fifth aspect of the invention, since the position of the first member against the second member can be easily switched, it is not necessary to replace a rotary abrasive material itself at the rotating tool or to selectively use a rotating tool with a different rotary abrasive material attached thereto in view of the processing required, whereby grinding work can be easily performed.

According to the sixth aspect of the present invention, in addition to the effects of the invention of the second, third, or fifth aspect, especially when the section between the projections is used as an air-introducing portion, an airflow can smoothly pass through the air-introducing portion as the rotary abrasive material rotates, since the air-introducing portion is formed with an inclination by the abrasive sheet.

Claims

1. A rotary abrasive material, which is a disk-like object with an abrasive sheet (14) arranged on its front face and can grind an object to be ground by being attached to a rotating tool (G), wherein the rotary abrasive material (10) has a base plate (11) and an abrasive sheet installation portion (12); the base plate (11) being like a disk in a plan view and attachable to a rotating shaft (S) of the rotating tool (G) in the center thereof; the abrasive sheet installation portion (12) being provided extending in a radial outward direction of the base plate (11) and attached with the abrasive sheet (14) to the front face side thereof, and in the base plate (11) or the abrasive sheet installation portion (12) is provided an air-introducing portion (15) which is a space penetrating from the back face side to the front face side and through which an airflow passes from the back face side to the front face side as the rotary abrasive material (10) rotates.

2. The rotary abrasive material as set forth in claim 1, wherein the abrasive sheet installation portion (12) is a projection portion (12) provided in plurality so as to project in the radial outward direction of the base plate (11), wherein the air-introducing portion (15) is a space existing between the projection portions (12), and the abrasive sheet (14) is attached to the projection portion (12).

3. The rotary abrasive material as set forth in claim 2, wherein an outer circumferential connecting portion (16) is formed so as to connect an outer circumferential portion (12c) of the respective projection portion (12) to each other, whereby the air-introducing portion (15) is surrounded by the base plate (11), projection portion (12), and outer circumferential connecting portion (16).

4. A rotary abrasive material, which is a disk-like object with an abrasive sheet (14) arranged on its front face and can grind an object to be ground by being attached to a rotating tool (G), wherein the rotary abrasive material (10) has a base plate (11) that is like a disk in a plan view and attachable to a rotating shaft (S) of the rotating tool (G) in the center thereof; at least part of the front face side of the base plate (11) being attached with the abrasive sheet (14), and in this base plate (11) is provided an air-introducing portion (15) which is a space penetrating from the back face side to the front face side and through which an airflow passes from the back face side to the front-surface side as the rotary abrasive material (10) rotates.

5. A rotary abrasive material, which is a disk-like object with abrasive sheets (14, 23) arranged on its front face and can grind an object to be ground by being attached to a rotating tool (G), wherein the rotary abrasive material (10) comprises a first member (1), a second member (2), and an attachment position adjusting means (25), wherein the first member (1) has a base plate (11) and a projection portion (12); the base plate (11) being like a disk in a plan view and attachable to a rotating shaft (S) of the rotating tool (G) in the center thereof; the projection portion (12) being provided in plurality so as to project in the radial outward direction of the base plate (11) and having an abrasive sheet inserting space (15) between the projection portions (12); the abrasive sheet (14) being attached to a one-side face of the projection portion (12), and the second member (2) has a base plate (21); the base plate (21) being like a disk in a plan view and attachable to a rotating shaft (S) of the rotating tool (G) in the center thereof; the abrasive material (23) being disposed on a one-side face of the base plate (21) and at a position, in a plan view, corresponding to the abrasive sheet inserting space (15) of the first member (1), and the attachment position adjusting means (25) is a means for adjusting a relation of position in the axial direction in combining the first member (1) and second member (2), whereby the abrasive material (14) of the first member (1) and the abrasive material (23) of the second member (2) are alternatively disposed by combining the first member (1) and second member (2) so as to make the centers of the respective base plates (11, 21) meet, wherein the abrasive sheet (23) of the second member (2) can project and retract against the first member (1).

6. The rotary abrasive material as set forth in claim 2, wherein the abrasive sheet (14, 23) is disposed inclined against a rotating direction of the rotary abrasive material (10).

7. The rotary abrasive material as set forth in claim 3, wherein the abrasive sheet (14, 23) is disposed inclined against a rotating direction of the rotary abrasive material (10).

8. The rotary abrasive material as set forth in claim 5, wherein the abrasive sheet (14, 23) is disposed inclined against a rotating direction of the rotary abrasive material (10).