JP2013075345A - Rotary tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to attenuate vibration even though the rotary tool such as a grinding stone wheel partially collides.SOLUTION: The grinding stone wheel 20 as the rotary tool is detachably mounted to the spindle of a disk grinder by a rotary tool holder 21. The rotary tool holder 21 has a lock nut 25 attached to the spindle and a wheel washer 27 facing the back face side of the lock nut 25, the grinding stone wheel 20 is arranged therebetween. An inside elastic body 36 and an outside elastic body 37 are arranged between the wheel washer 27 and the grinding stone wheel 20, the outside elastic body 37 has a spring constant larger than that of the inside elastic body 36. The inclination of the grinding stone wheel is regulated by the outside elastic body 37 even though the grinding stone wheel 20 partially collides.

Description

  The present invention relates to a rotary tool that processes a workpiece by being rotated by a spindle of a power tool such as a disk grinder.

  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. As the rotary tool, there are a disc-shaped 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 workpiece. For example, in order to grind the surface of an object to be treated such as concrete or stone, a grindstone wheel provided with a diamond grindstone is selected as a rotating tool, and the surface is ground by a disc 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 the rotating tool attached to the power tool is pressed against the 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. It was. Therefore, in the disc grinder described in Patent Document 1, by disposing an elastic member made of rubber packing on the mounting portion of the disc grindstone, that is, the holder portion, the elastic member absorbs the impact generated during the grinding process. The vibration transmitted to the worker is reduced.

JP 2002-331454 A

  As described in Patent Document 1, when the entire front and back surfaces of the ring-shaped elastic member are brought into close contact with the wheel washer and the disc grindstone, that is, the grindstone wheel, the impact on the rotary tool is received on the entire surface of the elastic member. Thus, when machining is performed in a state where the work surface is loosely in parallel with the grindstone wheel, the impact of the grindstone wheel can be attenuated by the elastic member.

  However, when a part of the grindstone wheel is processed so as to be in contact with the surface of the workpiece, the grindstone wheel comes into contact with the workpiece in a state of being inclined with respect to the workpiece surface. Thus, when the grindstone wheel hits a portion, a load is applied to a part of the elastic member, and the grindstone wheel is greatly inclined with respect to the spindle, and the inner peripheral surface of the mounting hole provided in the center portion of the grindstone wheel is The vibration of the grinding wheel is transmitted to the spindle in strong contact with the inner mounting ring, and the vibration reduction effect is diminished. Further, since large deformation occurs in a part of the elastic member, permanent deformation of the elastic member is likely to occur. When the elastic deformation occurs permanently, the backlash between the grindstone wheel and the elastic member becomes large, so that the effect of absorbing the impact is reduced, and problems such as fluttering of the grindstone wheel due to backlash occur.

  An object of the present invention is to make it possible to dampen vibration even when a rotary tool such as a grindstone wheel hits a part.

  A rotary tool according to the present invention is a rotary tool that processes a workpiece by being rotated by a spindle that is rotationally driven by a drive source, and is opposed to a lock nut attached to the spindle and a back side of the lock nut. A wheel washer that is attached to the lock nut and the rotary tool is disposed between the lock nut, an inner elastic body that is disposed between the wheel washer and the rotary tool, the wheel washer, and the wheel It has an outer side elastic body which is arrange | positioned in the radial direction outer side of the said inner side elastic body between rotary tools, and has a larger spring constant than the said inner side elastic body.

  In the rotary tool of the present invention, a guide rod that passes through an insertion hole formed in the rotary tool is disposed in parallel with the lock nut between the lock nut and the wheel washer, and the rotary tool is disposed in the axial direction. In addition to guiding, the rotation of the rotary tool is restricted. In the rotary tool of the present invention, the axial thickness of the outer elastic body is made smaller than the thickness of the inner elastic body, and when a pressing force is applied to the rotary tool, the rotary tool moves the inner elastic body. After contracting, it hits the outer elastic body. In the rotary tool of the present invention, the outer elastic body is attached to the main portion having a smaller axial thickness than the inner elastic body, and has a spring constant smaller than the main portion and the main portion. And a composite part of the main part and the sub part is sandwiched between the lock nut and the wheel washer.

  In the rotary tool of the present invention, a protruding portion that protrudes in the axial direction is provided on the radially inner portion of the outer elastic body, and the amount of compression of the protruding portion is regulated radially outward from the protruding portion of the outer elastic body. A gap is provided. In the rotary tool of the present invention, an elastic member in which an inner portion forming the inner elastic body and an outer portion forming the outer elastic body are integrated is disposed between the wheel washer and the rotary tool, A protrusion having a smaller spring constant than the outer part is provided on the inner part, and a gap is provided on either the outer part or both front and rear surfaces. The rotary tool of the present invention is characterized in that the tip of the protrusion has an arcuate cross-sectional shape.

  The power tool of the present invention includes a drive source, a spindle that is rotationally driven by the drive source, and the rotary tool described above. The rotary tool holder of the present invention is a rotary tool holder that is detachably mounted on the spindle, and is attached to the spindle. A lock nut, a wheel washer attached to the lock nut facing the back side of the lock nut, and the rotary tool being disposed between the lock nut, and between the wheel washer and the rotary tool An inner elastic body disposed; and an outer elastic body that is disposed radially outside the inner elastic body between the wheel washer and the rotary tool and has a larger spring constant than the inner elastic body. And

  According to the present invention, between the rotary tool and the wheel washer, the inner elastic body is disposed on the radially inner side, and the outer elastic body is disposed on the radially outer side. The outer elastic body is more than the inner elastic body. The spring constant is larger, and the inner elastic body is more easily elastically deformed when a load is applied in the axial direction than the outer elastic body. Thus, when the work is performed with the rotary tool hitting the entire surface of the workpiece, the vibration applied to the rotary tool is absorbed by the elastic deformation of the inner elastic body. When a large load is applied to the rotating tool in the axial direction or when the rotating tool hits a part, the rotating tool comes into contact with the outer elastic body having a spring constant larger than that of the inner elastic body. Transmission is prevented, and the rotating tool is prevented from being greatly inclined, so that vibration can be damped even if the rotating tool hits a portion.

  Since the inclination of the rotary tool can be reduced, it is possible to prevent the mounting hole of the rotary tool from colliding with a member inside the rotary tool. Accordingly, vibration can be attenuated even when the rotary tool is inclined, and permanent deformation of the inner elastic body and the outer elastic body can be prevented to improve the durability of the rotary tool holder.

It is a partially notched front view which shows the disc grinder with which the grindstone wheel was mounted | worn with the rotating tool holder. FIG. 2 is an enlarged sectional view taken along line 2-2 in FIG. FIG. 3 is an enlarged view taken along line 3-3 in FIG. 1. FIG. 4 is an enlarged sectional view taken along line 4-4 in FIG. It is an expanded sectional view which shows the rotary tool holder shown by FIG. It is an expanded sectional view of the rotary tool holder which shows the state which is grinding the whole surface with a grindstone wheel. It is an expanded sectional view of the rotary tool holder which shows the state which is performing grinding work per part with a grindstone wheel. It is an expanded sectional view which shows the rotary tool holder which is other embodiment of this invention. It is an expanded sectional view which shows the rotary tool holder which is further another embodiment of this invention. It is an expanded sectional view which shows the rotary tool holder which is further another embodiment of this invention. It is an expanded sectional view which shows the rotary tool holder which is further another embodiment of this invention. It is sectional drawing which shows the elastic body shown by FIG. (A) is sectional drawing which shows the conventional rotary tool holder as a comparative example, (B) is sectional drawing which shows the state which is performing the grinding operation per part with a grindstone wheel.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The power tool shown in FIG. 1 is a portable or hand-held disc grinder 10. The disk grinder 10 is used for grinding the surface of concrete or stone as an object to be processed, and is also called a disk sander.

  The disc grinder 10 has a cylindrical motor case 11a and a gear case 11b attached to the tip thereof, and an electric motor 12 is accommodated in the motor case 11a as a power source as shown in FIG. The electric motor 12 is connected to a commercial power source (not shown) via a power cord 13 drawn from the rear end of the motor case 11a, and the electric motor 12 is driven by electric power supplied from the commercial power source. A bevel gear 15 is attached to the rotating shaft 14 of the electric motor 12, and a bevel gear 16 that meshes with the bevel gear 15 is attached to a spindle 17 that is disposed at right angles to the rotating shaft 14, and the spindle 17 is rotationally driven by the electric motor 12. The The spindle 17 is rotatably supported by a bearing 18 attached to the gear case 11b.

  The tip of the spindle 17 protrudes from the gear case 11 b, and a cup-type grinding wheel 20 as a rotary tool is detachably attached to the tip by a rotary tool holder 21. The rotary tool holder 21 is attached to the spindle 17 in a state of being abutted against the abutting surface 19 formed on the spindle 17. The grindstone wheel 20 has a substrate 22 formed in a cup shape from a steel plate. As shown in FIG. 3, the front surface of the substrate 22 has a plurality of diamond grindstones 23a extending in the circumferential direction on the outer peripheral portion thereof and a radial direction. A plurality of diamond grindstones 23b extending to each other are fixed by means such as brazing. The substrate 22 is provided with a plurality of through holes 24 at intervals in the circumferential direction, and a lightening process is performed for weight reduction.

  As shown in FIG. 5, the rotary tool holder 21 has a lock nut 25 attached to the tip of the spindle 17. The lock nut 25 has a disk-shaped disk portion 25 a and a disk portion 25 a on the back side thereof. And a cylindrical boss portion 25b integrated therewith. A screw hole 26 is formed coaxially with the boss portion 25 b in the disk portion 25 a, and the lock nut 25 is attached to and detached from the spindle 17 by screwing a male screw 17 a provided at the tip of the spindle 17 to the screw hole 26. Can be attached freely.

  As shown in FIG. 5, a wheel washer 27 made of a disk-shaped member is attached to the lock nut 25 so as to face the back side of the lock nut 25. A recess 28 into which the boss 25b of the lock nut 25 is fitted is formed on the front surface of the wheel washer 27, and the wheel washer 27 is assembled to the lock nut 25 by fitting the recess 28 into the boss 25b. A mounting space 29 is formed between the wheel washer 27 and the disk portion 25a of the lock nut 25. The axial dimension of the mounting space 29 is set by the length of the boss portion 25b.

  A mounting hole 31 that is fitted to the boss portion 25b of the lock nut 25 is formed in the central portion in the radial direction of the grindstone wheel 20, and the mounting hole 31 has an inner diameter slightly larger than the outer diameter of the boss portion 25b. It has become. Between the disk portion 25a of the lock nut 25 and the wheel washer 27, a plurality of guide rods 32 are provided in parallel with the boss portion 25b. In the illustrated case, four guide rods 32 are provided every 90 degrees in the circumferential direction, and each guide rod 32 passes through an insertion hole 33 formed in the grindstone wheel 20. The guide rod 32 prevents the grindstone wheel 20 from rotating relative to the rotary tool holder 21, and the grindstone wheel 20 is guided by the guide rod 32 and is movable in the axial direction along the boss portion 25b. .

  One end of each guide rod 32 is fitted in a recess 34 formed in the wheel washer 27, and the other end is fitted in a recess 35 formed in the disk portion 25a. The guide rod 32 is formed by a spring pin in which a slit extending in the axial direction is formed in the tubular member, and is elastically deformed in the radial direction. Before the guide rod 32 is assembled between the wheel washer 27 and the disk portion 25a, the guide rod 32 is larger than the inner diameter of the recesses 34 and 35, and the guide rod 32 is compressed and contracted in the radial direction so as to be recessed. It is press-fitted inside and fixed to the wheel washer 27 and the disk portion 25a.

  Between the wheel washer 27 and the grindstone wheel 20, an inner elastic body 36 is disposed on the radially inner side, and an outer elastic body 37 is disposed on the radially outer side. As shown in FIG. 5, the inner elastic body 36 and the outer elastic body 37 are sandwiched between the front surface of the wheel washer 27 and the rear surface of the grinding wheel 20. As described above, the grindstone wheel 20 and the elastic bodies 36 and 37 are disposed between the two members, ie, the lock nut 25 and the wheel washer 27, each of which is a disk-like member. On the front surface of the wheel washer 27, an abutting surface 38 on which the inner elastic body 36 and the outer elastic body 37 are abutted is formed, and a protrusion 39 is annularly provided on the outer periphery of the front surface. As shown in FIG. 4, the inner elastic body 36 and the outer elastic body 37 are each formed in a ring shape from a rubber material, and the inner elastic body 36 has a smaller spring constant than the outer elastic body 37. That is, when the same load is applied to the inner elastic body 36 and the outer elastic body 37 in the axial direction, the inner elastic body 36 has a larger amount of elastic deformation in the axial direction. By making the components of the rubber material different between the inner elastic body 36 and the outer elastic body 37, it is possible to make a difference in the amount of elastic deformation in both axial directions, and the inner elastic body 36 is more than the outer elastic body 37. The hardness is also easily elastically deformed. As for the spring constants of the inner elastic body 36 and the outer elastic body 37, for example, natural rubber having a Shore hardness of 45 as the inner elastic body 36 and a Shore hardness of 65 as the outer elastic body 37 can be used. The spring constant is selected depending on other factors such as shape and area. The material of the elastic body may be a sponge rubber.

  As described above, when the inner elastic body 36 is more easily elastically deformed than the outer elastic body 37, when the entire grinding wheel 20 is pressed against the surface of the workpiece, The transmitted vibration is absorbed by the inner elastic body 36, and the impact during grinding is effectively reduced by the inner elastic body 36. On the other hand, the outer elastic body 37 is harder to be elastically deformed than the inner elastic body 36, and even if the grinding wheel per part is ground by pressing a part of the grinding wheel 20 against the surface to be processed, The inclination can be kept small and vibration is absorbed by the contact between the outer elastic body 37 and the grinding wheel 20.

  FIG. 6 shows a state where the grinding wheel 20 is ground by the grinding wheel 20 and the grinding wheel 20 is moved in the axial direction, and FIG. 7 shows a state where the grinding wheel 20 is ground and the grinding wheel 20 is inclined slightly. Show.

  If the inclination of the grinding wheel 20 can be reduced during the grinding operation per part, the collision between the mounting hole 31 of the grinding wheel 20 and the boss portion 25b is avoided, so that the vibration damping effect due to the collision is reduced. Can be prevented. Furthermore, since the inner elastic body 36 and the outer elastic body 37 can be prevented from being excessively deformed by reducing the inclination angle, permanent deformation of these elastic bodies can be prevented, and the durability of the elastic body is improved. can do.

  8 to 11 are sectional views showing a rotary tool holder 21 according to another embodiment of the present invention. In each figure, the same code | symbol is attached | subjected to the member which is common in the member which comprises the rotary tool holder shown in FIGS.

  In the rotary tool holder 21 shown in FIG. 8, the axial thickness of the outer elastic body 37 is smaller than the thickness of the inner elastic body 36 when the grinding work by the grindstone wheel 20 is not performed. As a result, the inner elastic body 36 contacts the grinding wheel 20 and is sandwiched between the grinding wheel 20 and the wheel washer 27, whereas a gap 41 is provided between the outer elastic body 37 and the grinding wheel 20. Is provided. As described above, when the inner elastic body 36 is thicker than the outer elastic body 37, the grinding wheel 20 can be used regardless of whether the grinding work is performed on the entire surface by the grinding wheel 20 or the grinding work per part. Until the outer elastic body 37 comes into contact with the outer elastic body 37, the inner elastic body 36 having a small spring constant can absorb vibration during grinding and effectively reduce the impact. If the grinding wheel 20 hits the outer elastic body 37 having a large spring constant after the grinding wheel 20 is strongly pressed and the inner elastic body 36 is mainly contracted, excessive axial movement and excessive tilt displacement of the grinding wheel 20 are caused by the outer elastic body. 37 suppresses vibration while attenuating. In the embodiment shown in FIG. 8, the outer elastic body 37 contacts the wheel washer 27 and a gap 41 is provided between the outer elastic body 37 and the grindstone wheel 20. 20 can be brought into contact with the outer elastic body 37 and the abutting surface 38 of the wheel washer 27, and the same effect can be achieved.

  The rotary tool holder 21 shown in FIG. 9 is formed by a main portion 37a having an outer elastic body 37 whose thickness is smaller than that of the inner elastic body 36, and a sub-portion 37b incorporated in a recess 42 formed in the radially inner portion. Has been. The total thickness of the composite portion formed by the main portion 37a and the sub portion 37b is substantially the same as the thickness of the inner elastic body 36, and the composite portion is sandwiched between the lock nut 25 and the wheel washer 27. Yes. A stepped portion 43 for forming a gap 41 with the end surface of the outer peripheral portion of the main portion 37a is provided on the outer peripheral portion of the abutting surface 38 of the wheel washer 27. The step portion 43 protrudes forward from the abutting surface 38. The main portion 37a and the sub portion 37b are formed of rubber materials having different characteristics, and the sub portion 37b has a smaller spring constant and a smaller diameter than the main portion 37a.

  In the rotary tool holder 21 of this form, the grinding wheel 20 is attached to the main portion 37a of the outer elastic body 37 regardless of whether grinding work per whole surface or grinding work per part is performed by the grinding wheel 20. Until the contact occurs, the inner elastic body 36 absorbs vibration during grinding and the sub-part 37b also absorbs vibration, and the impact can be effectively reduced. When the grinding wheel 20 is strongly pressed, the grinding wheel 20 hits the main portion 37a of the outer elastic body 37, and excessive axial movement and excessive tilt displacement of the grinding wheel 20 are suppressed. In particular, it is possible to reduce the inclination angle of the grindstone wheel 20 while sufficiently securing the amount of elastic deformation of the sub-part 37b by making the stepped part 43 approach the front of the rotary tool holder 21 to reduce the gap 41. it can.

  In the rotary tool holder 21 of this form, the same effect can be obtained even when the gap 41 is formed between the outer elastic body 37 and the grindstone wheel 20 by inverting the upper and lower sides of the outer elastic body 37 in FIG. Can be obtained.

  In the rotary tool holder 21 shown in FIG. 10, a protruding portion 37c protruding in the axial direction is provided on the radially inner portion of the outer elastic body 37, and the tip of the protruding portion 37c is an arc surface. By providing the protrusion 37c on the radially inner side of the outer elastic body 37, the thickness of the radially inner side of the outer elastic body 37 is larger than the thickness of the radially outer part. The outer elastic body 37 including the projecting portion 37c is formed of the same kind of rubber material, and the gap between the step 43 formed on the front surface of the wheel washer 27 and the outer peripheral portion of the outer elastic body 37 is shown in FIG. Similar to the case shown, a gap 41 is formed.

  In this rotary tool holder 21, the outer elastic body 37 is formed of a material having a larger spring constant than the inner elastic body 36, including the protruding portion 37 c, but the protruding portion 37 c is elastically deformed because of its small volume. It is easy. Thereby, even when grinding work per part is performed, the inner elastic body 36 absorbs vibration during grinding and the protrusion 37c also absorbs vibration until the grindstone wheel 20 contacts the outer peripheral portion of the outer elastic body 37. Therefore, the impact can be effectively reduced. In particular, since the tip of the protrusion 37c is an arc surface, the protrusion 37c is easily elastically deformed.

  In the rotary tool holder 21 shown in FIG. 11, the inner elastic body 36 and the outer elastic body 37 in each of the rotary tool holders 21 described above are formed of different types of rubber materials, whereas the same type of rubber material is used. Thus, an inner part forming the inner elastic body 36 and an inner part forming the outer elastic body 37 are formed as an integral elastic body 44. FIG. 12 is a cross-sectional view showing the integrated elastic body 44 shown in FIG. 11. The radially inner portion of the elastic body 44 corresponds to the inner elastic body 36 described above, and the outer portion corresponds to the outer elastic body 37. Equivalent to. The elastic body 44 is provided with a projecting portion 45 whose tip surface is arcuate on the radially inner side, and is similarly provided with a projecting portion 37c whose tip surface is arcuate on the radially outer portion. Yes. Since the elastic body 44 has a portion corresponding to the inner elastic body 36 and the outer elastic body 37 as a whole, a mounting hole 44a through which the boss 25b passes is formed at the center.

  As described above, by providing the integral elastic body 44 with the projecting portion 45 having the arcuate tip surface, the amount of elastic deformation in the axial direction is larger in the radial inner portion than in the outer portion, and the spring constant is substantially increased. Becomes smaller than the outer portion. The rotary tool holder 21 shown in FIG. 11 can obtain the same effects as described above by using the integrated elastic body 44 made of one kind of rubber material without using a plurality of elastic bodies.

  When assembling each of the rotary tool holders 21 described above, the boss portion 25b of the lock nut 25 is placed with the elastic body and the grindstone wheel 20 disposed between the back surface of the lock nut 25 and the front surface of the wheel washer 27. Is press-fitted into the recess 28 of the wheel washer 27. In this way, the rotary tool holder 21 is screwed to the spindle 17 with the grindstone wheel 20 held by the rotary tool holder 21. At that time, in order to rotate the rotary tool holder 21, as shown in FIG. 3, a plurality of engagement holes 46 with which a jig (not shown) is engaged are formed in the front surface of the lock nut 25. When the rotary tool holder 21 is screwed to the male screw 17a of the spindle 17 or unscrewed, the operation button 47 is axially attached to the gear case 11b in order to restrict the rotation of the spindle 17 as shown in FIG. It is mounted so as to be reciprocally movable, and when the operation button 47 is pushed in, the rotation of the spindle 17 is prevented.

  13A and 13B are sectional views showing a conventional rotary tool holder 21a shown as a comparative example. The wheel washer 27 that abuts against the abutment surface 19 of the spindle 17 has an annular base 51 and a spacer 52 that is assembled thereto. The spacer 52 has a disk portion 52a and a boss portion 52b integrated therewith. On the other hand, the lock nut 25 screwed to the male screw 17a of the spindle 17 does not have the above-described boss portion 25b, and is formed only by the disk portion 25a in which the screw hole 26 is formed. A grindstone wheel 20 and an elastic body 53 are disposed between the disk portion 52a of the spacer 52 and the lock nut 25. By screwing the lock nut 25 to the spindle 17, the elastic body 53 and the grindstone wheel 20 are disposed. Are attached to the spindle 17.

  In order to move the grinding wheel 20 in the axial direction with respect to the boss portion 52b, a spline 54 is formed on the outer periphery of the boss portion 52b, and a spline 54a that meshes with the spline 54 is formed in the mounting hole 31 of the grinding wheel 20. Has been. As shown in FIG. 13, when the entire front and back surfaces of the elastic body 53 are brought into contact with the disk portion 52 a and the grinding wheel 20, the grinding wheel 20 becomes a workpiece as shown in FIG. When the part is in a contact state and tilts, the spline 54a of the mounting hole 31 of the grindstone wheel 20 comes into contact with the spline 54 of the boss part 52b. For this reason, the vibration of the grinding wheel 20 is transmitted to the spindle 17 and the vibration damping effect is reduced. On the other hand, in the rotary tool holder 21 described above, since the inclination of the grindstone wheel 20 is suppressed by the outer elastic body 37 and the vibration is absorbed, the mounting hole 31 can be formed even if grinding is performed per part. Vibration transmission caused by collision with the boss portion 25b can be reliably prevented.

  The lock nut 25 of the rotary tool holder 21 described above has a boss portion 25b and the wheel washer 27 is formed of one member. However, as shown in FIG. 13, the lock nut 25 has a structure having only a disk portion 25a. The wheel washer 27 may be formed by an annular base 51 and a spacer 52 assembled to the annular base 51.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, as the arrangement of the elastic body, as shown in FIG. 4, the inner elastic body and the outer elastic body are completely separated in the radial direction, but a part thereof may overlap in the radial direction. Further, the embodiment shows the disc grinder 10 as a power tool. However, if the power tool uses a rotary tool as a tip tool, the rotary tool holder of the present invention can be applied to attach the rotary tool to the spindle. The illustrated disc grinder 10 uses the electric motor 12 as a power source and is driven by an external power source. However, the rotary tool holder of the present invention is also applied to a power tool incorporating a battery. The present invention can also be applied, and can be applied to a mode in which an air motor or a motor is used as a power source.

DESCRIPTION OF SYMBOLS 10 ... Disc grinder, 11a ... Motor case, 11b ... Gear case, 12 ... Electric motor, 13 ... Power cord, 14 ... Rotating shaft, 15, 16 ... Bevel gear, 17 ... Spindle, 17a ... Male screw, 18 ... Bearing, 19 ... Thing 20: grinding wheel, 21 ... rotary tool holder, 22 ... substrate, 23a, 23b ... diamond grinding wheel, 24 ... through hole, 25 ... lock nut, 25a ... disk part, 25b ... boss part, 26 ... screw hole, 27 ... Wheel washer, 28 ... Recess, 29 ... Installation space, 31 ... Installation hole, 32 ... Guide rod, 33 ... Insertion hole, 34, 35 ... Recess, 36 ... Inner elastic body, 37 ... Outer elastic body, 37a ... Main Part, 37b ... sub-part, 37c ... projection part, 38 ... abutting surface, 39 ... projection, 41 ... gap, 42 ... concave part, 43 ... step part, 44 ... elastic body, 45 The protruding portion, 46 ... engaging hole, 47 ... operation button.

Claims (9)

A rotary tool that rotates and drives a spindle driven by a drive source to process an object to be processed;
A lock nut attached to the spindle;
A wheel washer that is attached to the lock nut opposite to the back side of the lock nut and in which the rotary tool is disposed between the lock nut and the lock nut;
An inner elastic body disposed between the wheel washer and the rotary tool;
A rotary tool having an outer elastic body that is disposed radially outside the inner elastic body between the wheel washer and the rotary tool and has a larger spring constant than the inner elastic body.   Between the lock nut and the wheel washer, a guide rod penetrating an insertion hole formed in the rotary tool is arranged in parallel with the lock nut, guiding the rotary tool in the axial direction and A rotary tool characterized by restricting rotation.   When the axial thickness of the outer elastic body is made smaller than the thickness of the inner elastic body, and the pressing force is applied to the rotary tool, the outer elastic body after the rotary tool contracts the inner elastic body The rotary tool according to claim 1 or 2, wherein   The outer elastic body is attached to the main portion with a smaller axial thickness than the inner elastic body, and has a smaller spring constant than the main portion and a smaller diameter than the main portion. The rotary tool according to claim 1, wherein a composite portion of the main portion and the sub portion is sandwiched between the lock nut and the wheel washer.   Protruding portions protruding in the axial direction are provided on the radially inner portion of the outer elastic body, and a gap for restricting the amount of compression of the protruding portion is provided radially outward from the protruding portion of the outer elastic body. The rotary tool according to claim 1 or 2.   An elastic member in which an inner portion forming the inner elastic body and an outer portion forming the outer elastic body are integrated is disposed between the wheel washer and the rotary tool, and the inner portion is more than the outer portion. The rotary tool according to claim 1, wherein a protrusion having a small spring constant is provided, and a gap is provided on either the outer portion or both the front and rear surfaces.   The rotary tool according to claim 4 or 5, wherein the tip of the protrusion has an arcuate cross-sectional shape. A driving source;
A spindle driven to rotate by the drive source;
A power tool comprising: the rotary tool according to claim 1. A rotary tool holder for detachably mounting a rotary tool, which is rotationally driven by a spindle driven to rotate by a drive source, to process an object to be processed;
A lock nut attached to the spindle;
A wheel washer that is attached to the lock nut opposite to the back side of the lock nut and in which the rotary tool is disposed between the lock nut and the lock nut;
An inner elastic body disposed between the wheel washer and the rotary tool;
A rotary tool holder, comprising: an outer elastic body that is disposed radially outside the inner elastic body between the wheel washer and the rotary tool and has a larger spring constant than the inner elastic body.

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