JP2014018938A - Rotary tool and power tool including the same - Google Patents

Abstract

An object of the present invention is to suppress deterioration of vibration during rotation of a grindstone wheel with no load without impeding the effect of reducing vibration during grinding.
A grinding wheel, a center hole provided in a substrate of the grinding wheel, a lock nut having a boss inserted into the wheel, and a wheel washer that holds the substrate together with the lock nut. 6, an annular elastic body 5 interposed between the substrate 2 and the wheel washer 6, an annular adapter 30 is integrally provided around the center hole 2 a, and the annular adapter 30 is an axis of the boss portion 21. It is slidable in the direction. The lock nut 20 and the annular adapter 30 are in close contact with each other at the tapered surfaces 23 and 33, and a force in a direction in which the eccentricity of the center hole 2 a with respect to the screw hole of the lock nut 20 is reduced by the elastic force of the elastic body 5 is applied. I am doing so.
[Selection] Figure 1

Description

  The present invention relates to a rotary tool such as a rotating grindstone for processing a surface of a workpiece and a power tool including the rotary tool.

  There is a disc grinder or the like as a power tool for processing a surface of an object to be processed by driving a rotary tool such as a rotating grindstone by a power source. A disk grinder is used for grinding a surface of an object to be processed by driving a rotary tool by an electric motor or an air motor. Examples of the rotary tool include a disc-shaped grindstone (disk grindstone), a diamond cutter, a cup-shaped grindstone, a wire brush, and the like, and an arbitrary rotary tool is selected according to the type of the object to be processed. For example, in order to grind the surface of an object to be treated such as concrete or stone, a cup-shaped or disk-shaped grindstone provided with a diamond layer is selected as a rotating tool, and the surface is ground by a disk grinder. . A disk grinder that grinds the surface of an object to be processed with such a rotating tool is also called a disk sander or a polisher.

  When a rotating tool attached to the spindle of a power tool is pressed against a workpiece to perform processing such as grinding, vibration due to impact applied to the rotating tool during processing is directly transmitted to the operator, making long-term continuous work difficult. Met. Therefore, in the disc grinder described in Patent Document 1 below, by disposing an elastic body made of rubber packing on the mounting portion of the disc grindstone, that is, the holder portion, the impact generated during grinding is absorbed by the elastic body, and the disc grindstone The vibration transmitted to the operator is reduced.

JP 2002-331454 A

  FIG. 7 shows an example of a conventional rotary tool having a structure that absorbs an impact with an elastic body as in Patent Document 1. In this figure, a cup-shaped grindstone as a rotary tool has a grindstone wheel 1, a lock nut 4, an elastic body 5, a wheel washer 6, and a spring pin 7. The grinding wheel 1 is obtained by brazing a plurality of diamond layers 3 to a substrate 2, and a boss portion 4 a of a lock nut 4 is placed on one side of the substrate 2 (side on which the diamond layer 3 is provided) in a central hole 2 a of the substrate 2. The annular elastic body 5 and the wheel washer 6 are disposed on the other side of the substrate 2. The spring pin 7 is inserted between the hole 4 b of the lock nut 4 and the hole 6 b of the wheel washer 6 with the elastic body 5 interposed between the substrate 2 and the wheel washer 6.

  The lock nut 4 is provided with a female screw, and is attached to the spindle of the power tool. The power of the spindle is transmitted from the lock nut 4 to the grindstone wheel 1 through the spring pin 7, and grinding work is performed.

  As shown in FIG. 7, the entire front and back surfaces of the annular elastic body 5 are in close contact with the wheel washer 6 and the grinding wheel 1, so that the elastic body 5 can receive an impact applied to the grinding wheel 1 during the grinding operation. Therefore, vibration during work can be reduced.

  However, in the conventional example of FIG. 7, the grinding wheel 1 must be movable in the axial direction in order to receive the impact at the time of grinding work by the elastic body 5, so the center hole 2 a of the substrate 2 and the lock nut 4 Since the boss portion 4a is in a loosely fitted state, when the grinding wheel 1 rotates, the grinding wheel 1 rotates in an eccentric state by the backlash due to the unbalance of the grinding wheel 1, and the unbalance increases. Therefore, there is a problem that the vibration is worsened (increased). It is ideal that the grinding wheel 1 and the lock nut 4 are fitted with no backlash, and if the backlash can be reduced, the deterioration of vibration can be suppressed. However, increasing the processing accuracy of the components causes an increase in cost. Since the smooth movement of the grinding wheel 1 in the axial direction during the grinding operation is hindered, the vibration reducing effect by the elastic body 5 is not easily obtained. In the case of Patent Document 1 described above, it is assumed that the same problem occurs.

  The present invention has been made in recognition of such a situation, and the object thereof is to suppress the deterioration of vibration during rotation of the tool wheel under no load without interfering with the effect of reducing vibration during work of the tool wheel. It is in providing a rotary tool and a power tool provided with the same.

One embodiment of the present invention is a rotary tool. The rotary tool includes a tool wheel, a center hole provided in the substrate of the tool wheel, a lock nut having a boss portion inserted into the center hole from one side of the substrate, and the other side of the substrate A wheel washer that sandwiches the substrate together with the lock nut, and an elastic body interposed between the substrate and the wheel washer,
An annular convex portion is integrally provided around the center hole, and the annular convex portion is slidable in the axial direction of the boss portion, and the annular convex portion and the lock nut are in contact with each other. At least one of the contact portions is a tapered surface.

  The said aspect WHEREIN: The said taper surface is formed in the outer periphery of the said cyclic | annular convex part, and it is good for the surface or corner | angular part which contacts the said taper surface to be formed in the said lock nut.

  The said aspect WHEREIN: The taper surface which contacts the outer peripheral surface or corner | angular part of the said annular convex part is good to be formed in the said lock nut.

  In the above aspect, the inner periphery of the annular convex portion is a circumferential surface having a constant inner diameter, and the circumferential surface is slidably fitted to the outer periphery of the boss portion.

  In the above aspect, it is preferable that a first taper surface is formed on an inner periphery of the annular convex portion, and a second taper surface contacting the first taper surface is formed on an outer periphery of the boss portion. The inner periphery of the annular convex portion may be a circumferential surface having a constant inner diameter over a predetermined length in the axial direction of the boss portion, and the circumferential surface may be slidably fitted to the boss portion.

  Another aspect of the present invention is a power tool, comprising a drive source, a spindle that is rotationally driven by the drive source, and the rotary tool that is attached to the spindle.

  It should be noted that any combination of the above-described constituent elements, and those obtained by converting the expression of the present invention between methods and systems are also effective as aspects of the present invention.

  According to the present invention, when the tool wheel is sandwiched between the lock nut and the wheel washer, the annular convex portion is integrally provided around the center hole provided in the substrate of the tool wheel. A direction in which the eccentricity of the center hole of the board with respect to the screw hole of the lock nut is reduced by the elastic force of the elastic body interposed between the board and the wheel washer, with at least one of the contact portions where the lock nut contacts each other as a tapered surface The force is applied to the substrate. Therefore, it is possible to eliminate the play in the radial direction at the portion where the tool wheel is slidably supported by the lock nut. Since there is no radial backlash, the tool wheel unbalance is not amplified during the rotation of the tool wheel with no load, so that deterioration (increase) in vibration can be suppressed. When the tool wheel is pressed against the workpiece during grinding or other work, the taper surface moves away from the contact area, preventing the annular projection from moving in the axial direction of the lock nut boss. There is no.

It is a rotary tool by the 1st Embodiment of this invention, Comprising: (A) is side sectional drawing (II sectional drawing of FIG. 2) which shows a no-load state, (B) pressed against the to-be-processed object. It is a sectional side view (II sectional view taken on the line of FIG. 2) which shows a case. It is a rotary tool by 1st Embodiment, Comprising: (A) is a bottom view, (B) is a top view. These are side views which made a part of disc grinder a power tool which attached the rotary tool by 1st Embodiment in the cross section. It is a sectional side view of the rotary tool by the 2nd Embodiment of this invention. It is a sectional side view of the rotary tool by the 3rd Embodiment of this invention. It is a sectional side view of the rotary tool by the 4th Embodiment of this invention. It is a sectional side view of the conventional rotary tool.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or equivalent component, member, process, etc. which are shown by each drawing, and the overlapping description is abbreviate | omitted suitably. In addition, the embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

  1 (A), 1 (B) and 2 (A), 2 (B) show a cup-shaped grindstone 10 as a rotating tool according to the first embodiment of the present invention, and FIG. A disc grinder 50 as a power tool is shown.

  In these drawings, a cup-shaped grindstone 10 includes a grindstone wheel 1 as a tool wheel, a lock nut 20, an annular adapter 30 as an annular projection, an elastic body 5, a wheel washer 6, and a spring as a columnar member. And a pin 7.

  The grinding wheel 1 is formed on the outer peripheral portion of one surface of the substrate 2 formed in a cup shape with a steel plate (the side on which the concave portion for arranging the lock nut 20 and the like is formed), as shown in FIGS. As shown, a plurality of diamond layers 3a extending in the circumferential direction and a plurality of diamond layers 3b extending in the radial direction are respectively fixed by means such as brazing. A center hole 2 a is formed at the center of the substrate 2. An annular adapter 30 serving as an annular convex portion is integrally provided around the center hole 2a. The annular adapter 30 may be made of the same material as that of the substrate 2 or may be made of other metal, resin, hard rubber or the like. The annular adapter 30 is formed with a cylindrical extension 31 that forms a part of the inner peripheral surface 32 thereof. When the cylindrical extension 31 is press-fitted into the center hole 2a, the annular adapter 30 causes the lock nut 20 to move. It is being fixed to the board | substrate 2 so that it may become convex on the side to provide. Further, the inner peripheral surface 32 of the annular adapter 30 is a circumferential surface having a constant inner diameter, and is slidably fitted to the boss portion 21 of the lock nut 20. Therefore, the annular adapter 30 can move in the axial direction of the boss portion 21 of the lock nut 20 together with the substrate 2. Further, a conical taper surface 33 coaxial with the central axis of the inner peripheral surface (coincident with the center of the center hole 2a) is formed on the outer periphery of the annular adapter 30. The substrate 2 and the annular adapter 30 are formed with through holes 2b and 34 for allowing the spring pins 7 to pass therethrough. The through holes 2 b and 34 are sufficiently larger than the outer diameter of the spring pin 7 so that the substrate 2 can move in the axial direction of the boss portion 21.

  The lock nut 20 integrally has a boss portion 21 that is inserted from one side (the substrate surface side on which the diamond layers 3a and 3b are disposed) on the inner peripheral surface 32 of the annular adapter 30. An annular recess 22 into which the annular adapter 30 can be fitted is formed, and the inner peripheral surface thereof is a conical tapered surface 23 so that it can contact (contact) the conical tapered surface 33 of the annular adapter 30. The tapered inclination is the same so that the conical taper surface 23 on the lock nut 20 side and the conical taper surface 33 on the annular adapter 30 side can be exactly overlapped. A central through hole 24 in which a female screw 24 a is formed is formed at the center of the lock nut 20. The central axis of the central through hole 24 and the conical tapered surface 23 are coaxial. As shown in phantom lines in FIG. 1A, the female screw 24a of the central through hole 24 is a portion into which the male screw portion 51a of the spindle 51 of the disc grinder 50 is screwed. Further, a hole 25 for press-fitting the spring pin 7 is formed in the lock nut 20. The material of the lock nut 20 is steel or the like as with a general nut.

  The wheel washer 6 has a disc shape, and a central hole 6a is formed at the center thereof, and a stopper cylindrical portion 6b is formed at the outer peripheral edge. The center hole 6a is composed of a small diameter portion and a large diameter portion, and the tip surface of the boss portion 21 abuts on a step surface 6c between the small diameter portion and the large diameter portion. The wheel washer 6 is formed with a hole 6d for press-fitting the spring pin 7. The stopper cylindrical portion 6b has a function of contacting the substrate 2 when the substrate 2 is inclined and preventing further inclination of the substrate 2. The material of the wheel washer 6 is a steel material as in the case of a general washer, for example, the same material as that of the lock nut 20.

  The elastic body 5 is a circular ring having a rectangular cross section having a through hole 5 a that passes through the boss portion 21 of the lock nut 20, and is made of a material such as elastic rubber, and is disposed inside the stopper cylindrical portion 6 b of the wheel washer 6. ing. The elastic body 5 is formed with a through hole 5b through which the spring pin 7 passes.

  The assembly procedure of the cup-shaped grindstone 10 as a rotary tool is as follows. The annular adapter 30 is press-fitted and integrated on the side of the grindstone wheel 1 on which the concave portion of the substrate 2 is formed, and the boss portion 21 is formed so that the lock nut 20 covers the annular adapter 30. Insert into the inner peripheral surface 32. The elastic body 5 and the wheel washer 6 are fitted in this order on the boss portion 21 protruding to the opposite side of the substrate 2 and inserted into the through holes 34, 2b, 5b provided in the annular adapter 30, the substrate 2 and the elastic body 5. One end of the spring pin 7 is press-fitted into the hole 25 of the lock nut 20, and the other end is press-fitted into the hole 6 d of the wheel washer 6, and the lock nut 20 is interposed between the substrate 2 and the wheel washer 6. And the wheel washer 6 sandwich the grinding wheel 1. The spring pins 7 are provided at a plurality of locations.

  A disc grinder 50 as a power tool capable of mounting a cup-shaped grindstone 10 as a rotating tool will be described with reference to FIG. A main body case 52 of the disc grinder 50 is formed in a cylindrical shape, and an electric motor 53 as a drive source is accommodated therein. The electric motor 53 is connected to a commercial power source (not shown) via a power cord 54 drawn from the main body case 52, and is driven by electric power supplied from the commercial power source.

  A gear case 60 is attached to the distal end portion of the main body case 52, and a spindle 51 as an output shaft is rotatably supported by the gear case 60 by a pair of bearings 61 and 62. The spindle 51 is arranged orthogonal to the axial direction of the output shaft 53 a of the electric motor 53, and the tip portion projects from the gear case 60 to the outside. A pair of bevel gears 63 and 64 that mesh with each other are provided inside the gear case 60, and the rotation of the output shaft 53 a of the electric motor 53 is transmitted to the spindle 51 by changing the direction by 90 degrees by the bevel gears 63 and 64. ing.

  The mounting of the cup-shaped grindstone 10 on the spindle 51 will be described. The spindle 51 has a male screw part 51a having a thin step diameter at the tip, and the wheel washer 6 is disposed so as to abut on a seating surface 51b formed at the base of the male screw part 51a. Then, the cup-shaped grindstone 10 is fastened and fixed to the spindle 51 by screwing the male screw portion 51 a into the female screw 24 a of the lock nut 20 and tightening the lock nut 20.

  Since the boss portion 21 of the lock nut 20 is in contact with the step surface 6c of the wheel washer 6, the positional relationship between the lock nut 20 and the wheel washer 6 is not changed by tightening the lock nut 20, and the lock nut 20 is tightened. Therefore, the elastic body 5 is not strongly compressed. By setting the elastic body 5 to be held by the wheel washer 6 in a slightly compressed state, the elastic body 5 biases the substrate 2 toward the lock nut 20, and the conical taper surface 33 of the annular adapter 30. , The conical taper surface 23 of the lock nut 20 is in close contact with each other, and the center axis of the lock nut 20 and the center axis of the annular adapter 30 are eliminated so that the center axes coincide with each other (in other words, the lock nut 20 The force in the direction in which the eccentricity of the central hole 2a of the substrate 2 with respect to the 20 screw holes decreases is applied to the substrate 2). For this reason, the play in the radial direction of the grindstone wheel 1 with respect to the boss portion 21 of the lock nut 20 is eliminated, and the centering is performed. Since the centering is reliably performed, the unbalance of the grindstone wheel 1 due to the backlash is not amplified during the rotation operation when there is no load, so that deterioration (increase) of vibration can be prevented.

  The overall operation of the disc grinder 50 will be described. When a power switch (not shown) of the disc grinder 50 is operated to supply electric power to the electric motor 53, the electric motor 53 is operated to rotate the spindle 51, and the cup-shaped grindstone 10 fixed thereto is rotationally driven. That is, the power of the spindle 51 is transmitted from the lock nut 20 to the grinding wheel 1 through the spring pin 7 and the grinding wheel 1 rotates.

  At the time of no load at which the cup-shaped grindstone 10 shown in FIG. 1 (A) does not contact the workpiece, the conical taper surface 23 of the lock nut 20 and the conical taper surface 33 of the annular adapter 30 are in contact as described above. Both center axes coincide with each other to perform centering, thereby preventing an increase in vibration.

  On the other hand, during the grinding operation in which the cup-shaped grindstone 10 shown in FIG. 1 (B) is in contact with the workpiece, the grindstone wheel 1 is pushed toward the wheel washer 6 in the axial direction. Since it becomes the direction which leaves | separates, the movement to the axial direction of the grindstone wheel 1 is not prevented. Even when the conical tapered surfaces 23 and 33 are separated from each other, the inner circumferential surface 32 of the annular adapter 30 is a circumferential surface having a constant inner diameter, and slides with the boss portion 21 having the outer peripheral surface having a constant outer diameter of the lock nut 20. Since it fits freely, centering can be performed by the inner peripheral surface 32 of the annular adapter 30 and the outer peripheral surface of the boss portion 21.

  According to the present embodiment, the following effects can be achieved.

(1) The elastic body 5 urges the base plate 2 of the grinding wheel 1 toward the lock nut 20, and the conical taper surface 33 of the annular adapter 30 and the conical taper surface 23 of the lock nut 20 are in close contact with each other. In other words, the eccentricity of the central hole 2a of the substrate 2 with respect to the screw hole of the lock nut 20 is reduced. Since the force in the direction to be applied is applied to the substrate 2, there is no play in the radial direction of the grindstone wheel 1 with respect to the boss portion 21 of the lock nut 20, and centering is performed. Since the centering is reliably performed, the unbalance of the grindstone wheel 1 due to the backlash is not amplified during the rotation operation when there is no load, so that deterioration (increase) of vibration can be prevented.

(2) Since the boss portion 21 and the inner peripheral surface 32 of the annular adapter 30 are in a slightly loosely fitted state, even when the grinding wheel 1 is pushed to the wheel washer 6 side during grinding work, it is smooth. It is possible to move on. Thereby, the impact at the time of grinding work can be effectively attenuated by the elastic body 5, and the effect of vibration reduction can be maintained.

(3) By providing the conical taper surface 33 on the outer periphery of the annular adapter 30, the inner peripheral surface 32 of the annular adapter 30 fitted to the boss portion 21 of the lock nut 20 can be a circumferential surface having a constant inner diameter. The straight part with a constant inner diameter can be made sufficiently long. As a result, the grindstone wheel 1 can move smoothly with respect to the axial direction of the boss portion 21. It is also effective for suppressing the inclination of the grindstone wheel 1 during the grinding operation.

(4) It has a structure in which the annular adapter 30 is added to the substrate 2 of the grinding wheel 1, and since the substrate 2 can be manufactured by pressing a plate material, it can be manufactured at low cost. In addition, the fitting length of the conical tapered surfaces 23 and 33 can be designed to be long regardless of the thickness of the substrate 2.

  FIG. 4 shows a cup-shaped grindstone 10A as a rotary tool according to the second embodiment of the present invention (however, a cross-sectional view similar to the line II in FIG. 2). In this case, the cup-shaped grindstone 10A includes a grindstone wheel 1 as a tool wheel, a lock nut 40, an annular adapter 70, an elastic body 5, a wheel washer 6, and a spring pin 7 as a columnar member. Yes.

  The lock nut 40 integrally has a boss portion 41 inserted from one side (the substrate surface side on which the diamond layers 3a and 3b are disposed) on the inner periphery of the annular adapter 70, and the base side outer peripheral surface of the boss portion 41 is It is formed as a conical taper surface 42, and the outer peripheral surface on the tip side is formed as a circumferential surface 43 having a constant outer diameter. A central through hole 44 in which a female screw 44 a is formed is formed at the center of the lock nut 40. The central axis of the central through hole 44 is concentric with the conical taper surface 42 and the circumferential surface 43. The female screw 44a of the central through hole 44 is a portion into which the male screw part 51a of the spindle 51 of the disc grinder 50 shown in FIG. Further, the lock nut 40 is formed with a hole 45 for press-fitting the spring pin 7. The material of the lock nut 40 is steel or the like, as with a general nut.

  The annular adapter 70 is integrally provided around the center hole 2a of the substrate 2 to form an annular convex portion. The annular adapter 70 may be made of the same material as the substrate 2, or other metals, Resin, hard rubber, etc. may be used. The annular adapter 70 is formed with a cylindrical extension 71 that forms a part of the inner peripheral surface thereof. When the cylindrical extension 71 is press-fitted into the center hole 2a of the substrate 2, the annular adapter 70 is locked with a lock nut. 40 is fixed to the substrate 2 so as to be convex. The inner peripheral surface of the annular adapter 70 has a conical taper surface 72 corresponding to the conical taper surface 42 on the lock nut side and a circumferential surface 73 having a constant inner diameter corresponding to the circumferential surface 43 having a constant outer diameter. The conical taper surface 72 and the circumferential surface 73 having a constant inner diameter coincide with the central hole 2a of the substrate 2 and the central axis. The tapered inclination is the same so that the conical taper surface 42 on the lock nut 40 side and the conical taper surface 72 on the annular adapter 70 side can exactly overlap. The substrate 2 and the annular adapter 70 are formed with through holes 2b and 74 for allowing the spring pins 7 to pass therethrough. The through holes 2 b and 74 are sufficiently larger than the outer diameter of the spring pin 7 so that the substrate 2 can move in the axial direction of the boss portion 41.

  The assembly procedure of the cup-shaped grindstone 10A as a rotating tool is as follows. The annular adapter 70 is press-fitted and integrated with the side of the grindstone wheel 1 on which the concave portion of the substrate 2 is formed, and the boss portion 41 is formed so that the lock nut 40 covers the annular adapter 70. It is inserted into the inner periphery of the annular adapter 70. The elastic body 5 and the wheel washer 6 were fitted in this order on the boss 41 projecting on the opposite side of the substrate 2 and inserted into the annular adapter 70, the through holes 74, 2 b and 5 b provided in the elastic body 5. One end of the spring pin 7 is press-fitted into the hole 45 of the lock nut 40, and the other end is press-fitted into the hole 6 d of the wheel washer 6, and the lock nut 20 is interposed between the substrate 2 and the wheel washer 6. And the wheel washer 6 sandwich the grinding wheel 1. The spring pins 7 are provided at a plurality of locations.

  Also in the case of the second embodiment, the elastic body 5 biases the substrate 2 toward the lock nut 40 by setting the elastic body 5 so as to be held by the wheel washer 6 in a slightly compressed state. Thus, the conical taper surface 72 of the annular adapter 70 and the conical taper surface 42 of the lock nut 40 are in close contact with each other, so that the center axes of the lock nut 40 and the center axis of the annular adapter 70 are eliminated. It works to let you. For this reason, the play in the radial direction of the grindstone wheel 1 with respect to the boss portion 41 of the lock nut 40 is eliminated, and the centering is performed. Therefore, substantially the same effect as that of the first embodiment described above can be obtained.

  FIG. 5 shows a cup-shaped grindstone 10B as a rotary tool according to the third embodiment of the present invention (however, a cross-sectional view similar to the line II in FIG. 2). In this case, the cup-shaped grindstone 10B includes a grindstone wheel 1 as a tool wheel, a lock nut 80, an annular adapter 30, an elastic body 5, a wheel washer 6, and a spring pin 7 as a columnar member. Yes. The only difference is the shape of the lock nut 80 from the first embodiment, and the rest is the same as in the first embodiment. In this case, the lock nut 80 integrally has a boss portion 81, and an annular recess 82 into which the annular adapter 30 can be fitted is formed around the boss portion 81, and its inner peripheral surface rises vertically from the bottom surface of the recess 82. The peripheral edge is a corner 83. Accordingly, the conical taper surface 33 of the annular adapter 30 can be in contact with the corner 83 on the lock nut 80 side. A central through hole 84 in which a female screw 84 a is formed is formed at the center of the lock nut 80. The central axis of the central through hole 84 is coaxial with the circumferential surface 83 having the corner 83 as a leading edge.

  Also in the third embodiment, by setting the elastic body 5 to be held by the wheel washer 6 in a slightly compressed state, the elastic body 5 urges the substrate 2 to the lock nut 80 side, The conical taper surface 33 of the annular adapter 30 and the corner 83 of the lock nut 80 are in contact with each other, and the center axis of the lock nut 80 and the center axis of the annular adapter 30 are eliminated so that the center axes coincide with each other. To do. For this reason, there is no backlash in the radial direction of the grinding wheel 1 with respect to the boss portion 81 of the lock nut 80, and centering is performed. Therefore, substantially the same effect as that of the first embodiment described above can be obtained.

  FIG. 6 shows a cup-shaped grindstone 10C as a rotary tool according to the fourth embodiment of the present invention (however, a cross-sectional view similar to the II line in FIG. 2). In this case, the cup-shaped grindstone 10 </ b> C includes a grindstone wheel 1 as a tool wheel, a lock nut 20, an annular adapter 90, an elastic body 5, a wheel washer 6, and a spring pin 7 as a columnar member. Yes. Only the shape of the annular adapter 90 is different from that of the first embodiment, and the others are the same as those of the first embodiment. In this case, on the outer periphery of the annular adapter 90, a circumferential surface 93 having a constant diameter is formed coaxially with the central axis of the inner circumferential surface 92 (coincident with the center of the central hole 2a of the substrate 2). Therefore, the conical taper surface 23 of the lock nut 20 is configured to be able to contact the corner portion 95 that is the tip edge of the circumferential surface 93. The cylindrical extension 91 of the annular adapter 90 is fixed to the substrate 2 by being press-fitted into the center hole 2 a of the substrate 2, and the inner peripheral surface 92 having a constant inner diameter of the annular adapter 90 is connected to the boss portion 21 of the lock nut 20. It is the same as in the first embodiment that it is slidably fitted.

  Also in the fourth embodiment, by setting the elastic body 5 to be held by the wheel washer 6 in a slightly compressed state, the elastic body 5 biases the substrate 2 toward the lock nut 20, The corner 95 of the outer periphery of the annular adapter 90 and the conical taper surface 23 of the lock nut 20 are in contact with each other so that the center axes of the lock nut 20 and the center axis of the annular adapter 90 are not aligned with each other. Act on. For this reason, the play in the radial direction of the grindstone wheel 1 with respect to the boss portion 21 of the lock nut 20 is eliminated, and the centering is performed. Therefore, substantially the same effect as that of the first embodiment described above can be obtained.

  The present invention has been described above by taking the embodiment as an example. However, it is understood by those skilled in the art that various modifications can be made to each component and each processing process of the embodiment within the scope of the claims. By the way. Hereinafter, modifications will be described.

  In each embodiment, the annular adapters 30, 70, and 90, which are separate parts that are annular protrusions, are integrated with the substrate 2 of the grinding wheel 1, but the periphery of the center hole of the substrate 2 is partially thickened to form an annular shape. An annular convex portion having the same shape as the adapter may be formed in advance.

  In each embodiment, an elastic body for shock absorption may be interposed between the annular adapter serving as the annular protrusion and the lock nut. However, it is a premise that the annular adapter and the lock nut come into contact with each other at a predetermined contact portion when there is no load.

  It is obvious that the present invention can be applied to a rotary tool using a tool wheel other than a grinding wheel.

  Moreover, although the disk grinder was illustrated as an example of a power tool, it is not limited to this, and it is clear that the present invention can be applied if it has a structure in which a rotary tool is mounted on a spindle.

  Although an electric motor is shown as a drive source for the power tool, it is obvious that an air motor or a motor may be used as the drive source.

DESCRIPTION OF SYMBOLS 1 Grinding wheel 2 Substrate 2a Center hole 3, 3a, 3b Diamond layer 4, 20, 40, 80 Lock nut 5 Elastic body 6 Wheel washer 7 Spring pin 10, 10A, 10B, 10C Cup type grindstone 21, 41, 81 Boss part 23, 33, 42, 72 Conical taper surfaces 30, 70, 90 Annular adapter 50 Disc grinder 51 Spindle 53 Electric motor
83,95 corner

Claims (7)

A tool wheel,
A central hole provided in the substrate of the tool wheel;
A lock nut having a boss portion inserted into the center hole from one side of the substrate;
A wheel washer disposed on the other side of the substrate and sandwiching the substrate together with the lock nut;
An elastic body interposed between the substrate and the wheel washer;
An annular convex portion is integrally provided around the center hole, and the annular convex portion is slidable in the axial direction of the boss portion,
At least one of each contact part where the said annular convex part and the said lock nut contact mutually is a taper surface, The rotary tool characterized by the above-mentioned.   The rotary tool according to claim 1, wherein the tapered surface is formed on an outer periphery of the annular convex portion, and a surface or a corner portion that contacts the tapered surface is formed on the lock nut.   The rotary tool according to claim 1, wherein a tapered surface that contacts an outer peripheral surface or a corner of the annular convex portion is formed on the lock nut.   The inner circumference of the annular convex portion is a circumferential surface having a constant inner diameter, and the circumferential surface is slidably fitted to the outer circumference of the boss portion. Rotating tool.   2. The rotation according to claim 1, wherein a first taper surface is formed on an inner periphery of the annular convex portion, and a second taper surface that contacts the first taper surface is formed on an outer periphery of the boss portion. tool.   The inner circumference of the annular convex portion is a circumferential surface having a constant inner diameter over a predetermined length in the axial direction of the boss portion, and the circumferential surface is slidably fitted to the boss portion. The described rotary tool.   A power tool comprising: a drive source; a spindle that is rotationally driven by the drive source; and the rotary tool according to claim 1 attached to the spindle.