JP2013226650A - Power tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power tool suppressing the permanent deformation of an elastic member and maintaining a vibration reducing effect over a long period of time.SOLUTION: A rubber ring 25 serving as an elastic member is disposed between a wheel washer 22 mounted to a spindle 17, and a base 12a of a diamond grinding wheel 12, and these members are fixed with a lock nut 27 screw-connected to the tip of the spindle 17. Vibration received by the diamond grinding wheel 12 in grinding work is thereby absorbed by the rubber ring 25. A mounting hole 12c of the base 12a is loosely fitted to a boss 24 of the wheel washer 22, and a spring pin 28 with both ends supported by the wheel washer 22 and a portion of a presser plate 26 of the lock nut 27 is inserted in a loosely fitted state through an insertion hole 12d of the base 12a and an insertion hole 25a of the rubber ring 25.

Description

  The present invention relates to a power tool in which a wheel type (disc type) tip tool is attached to the tip of an output shaft, such as a portable disc grinder, and in particular, an attachment structure for attaching a wheel type tip tool to an output shaft. About.

  In a grinding operation in which the surface of concrete, stone, or the like is ground flat using a power tool such as an electric tool such as a disk grinder or a sander, an air tool, or an engine tool, a diamond grinding wheel is used as a tip tool. The diamond grinding wheel is a wheel type (disk type) in which a plurality of diamond grinding stones are fixed to the surface of a cup type substrate whose center is formed in a cup shape. ) And used.

  In grinding work using such a power tool, the diamond grindstone is pressed against the work material, and vibration due to impact during grinding is directly transmitted to the worker, making continuous work for a long time difficult. .

  For this reason, for example, in the power tool described in Patent Document 1, an elastic member is disposed on the attachment portion of the tip tool, and the impact generated during the grinding operation is received by the elastic member, thereby reducing vibration transmitted from the tip tool to the operator. I am doing so.

Utility Model Registration No. 3096194

  However, in grinding with a diamond wheel, the work is performed while moving the wheel back and forth or left and right. In this case, only a part of the surface of the lever hits the work piece.

  When the grindstone wheel hits the entire surface of the work material, the grindstone wheel moves in the axial direction along the output shaft, so that the elastic member is uniformly pressed by the substrate and uniformly elastically deformed. Become. Therefore, a large deformation does not occur in the elastic member.

  On the other hand, when grinding is performed with the grinding wheel in contact with the work piece, the substrate portion of the grinding wheel is in contact with the elastic member while being tilted with respect to the output shaft. However, only a part will be greatly deformed. Therefore, permanent deformation is likely to occur in the elastic member.

  When the elastic member undergoes permanent deformation, the backlash between the substrate portion of the grinding wheel and the elastic member increases, so that the effect of suppressing vibration by the elastic member is reduced, and the grinding wheel fluctuates during the grinding operation. It will cause problems.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a power tool that maintains the effect of reducing vibration over a long period of time by suppressing permanent deformation of the elastic member. It is.

  The power tool of the present invention includes a motor that is a power source, a spindle that is rotationally driven by the motor, an elastic member that is held by the spindle, a tip tool connected to the elastic member, and the tip tool. And a guide member for guiding in a spindle direction.

  The power tool of the present invention has a wheel washer connected to the spindle, the elastic member is held by the wheel washer, the guide member is a columnar member extending in the spindle direction, and the columnar The member penetrates the elastic member and the tip tool.

  The power tool of the present invention has a male screw part formed on the spindle, and has a lock nut having a female screw part engaged with the male screw part, and the columnar member is connected to the lock nut. It is characterized by that.

  In the power tool of the present invention, the wheel washer, the elastic member, the tip tool, the columnar member, and the lock nut are integrally fixed by the columnar member.

  The power tool according to the present invention is characterized in that a plurality of the columnar members are provided around the spindle.

In the power tool of the present invention, the elastic member is sandwiched between the wheel washer and the tip tool, and the wheel washer has a protrusion extending in the tip tool direction, and the protrusion is the elastic member. It is comprised so that it can contact the said tip tool when deform | transforming.

  The power tool according to the present invention is a power tool in which a wheel-type tip tool is attached to an output shaft, and a wheel washer attached to the output shaft, and the output with an axial distance from the wheel washer. A holding plate mounted on a shaft; a cylindrical portion provided on one of the wheel washer or the pressing plate; and a mounting hole provided between the wheel washer and the pressing plate and provided in an axis. The wheel washer is screwed to the tip of the output shaft, the substrate of the tip tool fitted to the cylindrical portion so as to be movable in the axial direction, an elastic member disposed between the wheel washer and the substrate, A lock nut for fixing the pressing plate and the cylindrical portion to the output shaft, and one end of the foil Ssha other end while being supported is supported on the pressing plate, and having a pin member passing through the said elastic member and the substrate.

  The power tool of the present invention is characterized in that the pressing plate and the lock nut are integrally formed.

  In the power tool of the present invention, the pin member is a spring pin.

  According to the present invention, since the tip tool connected to the elastic member is guided in the spindle direction by the guide member, the tip tool is inclined in response to the reaction force from the work material during the grinding operation. Can be suppressed. By suppressing the inclination of the tip tool, the elastic member can be prevented from being excessively deformed, and the elastic member can be made difficult to be permanently deformed. Thereby, permanent deformation of the elastic member can be suppressed, and the vibration suppressing effect of the elastic member can be maintained for a long period of time.

  According to the present invention, the pin member whose one end is supported by the wheel washer and the other end is supported by the holding plate penetrates the substrate and the elastic member. When it receives and moves to an axial direction, a board | substrate is guided to a cylindrical part in an attachment hole, and a pin member functions as a guide, and the inclination of a tip tool is suppressed. By suppressing the inclination of the tip tool, the elastic member can be prevented from being excessively deformed. For this reason, it becomes difficult for the elastic member to be permanently deformed. Thereby, permanent deformation of the elastic member can be suppressed, and the vibration suppressing effect of the elastic member can be maintained for a long period of time.

  According to the present invention, in the above configuration, the pressing plate is formed integrally with the lock nut, so that the number of parts can be reduced and the manufacturing cost of the power tool can be reduced.

  According to the present invention, in the above configuration, since the pin member is configured by the spring pin, the mounting operation of the pin member to the wheel washer and the holding plate and the operation of penetrating the substrate and the elastic member are facilitated. The manufacturing cost of the power tool can be reduced.

It is a partially cutaway sectional view of a disc grinder which is one embodiment of the present invention. (A) is the top view which looked at the attachment structure of the tip tool shown in FIG. 1 from arrow A, (b) is the bottom view. It is a longitudinal cross-sectional view of the attachment structure of the tip tool shown in FIG. It is an expanded sectional view which expands and shows the principal part of FIG. (A) is sectional drawing which shows the state of the attachment structure in grinding operation, (b) is sectional drawing which shows the state in which the pressing load of the diamond grindstone wheel became excessive. It is sectional drawing which shows the comparative example in which a spring pin is not provided, (a) is sectional drawing which shows a no-load state, (b) is sectional drawing which shows the state in which the diamond grindstone wheel contacted the whole surface of the workpiece, c) is a cross-sectional view showing a state in which a diamond grinding wheel is in contact with a work material. It is sectional drawing which shows the modification of the attachment structure shown in FIG.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  A disc grinder 11 as a power tool shown in FIG. 1 includes a diamond grindstone wheel 12 as a tip tool, and is used for an operation of grinding a surface of concrete, stone or the like flatly.

  A main body case 13 of the disc grinder 11 is formed in a cylindrical shape, and an electric motor 14 is accommodated therein as a drive source. The electric motor 14 is connected to a commercial power source (not shown) via a power cord 15 drawn from the main body case 13, and is driven by electric power supplied from the commercial power source.

  A gear case 16 is attached to the distal end portion of the main body case 13, and a spindle 17 as an output shaft is rotatably supported on the gear case 16 by a pair of bearings 18a and 18b. The spindle 17 is disposed orthogonal to the axial direction of the electric motor 14, and the tip portion thereof protrudes from the gear case 16 to the outside. A pair of bevel gears 19a and 19b meshed with each other is provided inside the gear case 16, and the rotation of the electric motor 14 is transmitted to the spindle 17 by changing the direction by 90 degrees by the bevel gears 19a and 19b. .

  As shown in FIG. 2, the diamond grindstone wheel 12 includes a substrate 12a formed in a disk shape from a steel plate, and a wheel type in which a plurality of diamond grindstones 12b having a predetermined shape are fixed to the surface of the substrate 12a by means such as adhesion. (Disc type). As shown in FIG. 3, the central portion of the substrate 12a is formed in a cup shape that is recessed in the axial direction, that is, the diamond grinding wheel 12 is of a cup type. A mounting hole 12c is provided in the center of the cup-shaped portion of the substrate 12a, and the diamond grinding wheel 12 is attached to the spindle 17 by the tip tool mounting structure 21 (hereinafter referred to as mounting structure 21) of the present invention. Is attached. The substrate 12a is provided with four through holes 12e arranged at equal intervals in the circumferential direction. These through holes 12e are provided in order to discharge chips such as a work material (concrete) from between the work material and the substrate 12a.

  When an operation unit of a power switch (not shown) of the disk grinder 11 is operated, power is supplied to the electric motor 14 and the electric motor 14 is activated. When the electric motor 14 is operated, the spindle 17 is rotationally driven by the electric motor 14, and the diamond grinding wheel 12 rotates together with the spindle 17. And the work which grinds the surface of a work material flat is performed by pressing the rotated diamond grindstone wheel 12 against the surface of work materials, such as concrete and stone. At this time, the portion of the mounting structure 21 that protrudes toward the workpiece with respect to the substrate 12a is disposed inside the cup shape of the substrate 12a, so that the entire surface of the diamond grinding wheel 12 is the surface of the workpiece. Can be pressed against.

  Next, details of the mounting structure 21 of the present invention will be described.

  As shown in FIG. 4, a wheel washer (flange) 22 is attached to the spindle 17. The wheel washer 22 is formed in a disk shape from a steel material or the like, and is inserted into the spindle 17 through a through hole 22a provided in the axial center thereof. The spindle 17 is provided with a male screw portion 17a having a thin step diameter at the tip portion, and a wheel washer 22 is disposed on a seat surface 17b formed at the root portion of the male screw portion 17a. In addition, the wheel washer 22 is prevented from rotating with respect to the spindle 17 by a rotation stopping means (not shown) so as to rotate integrally with the spindle 17.

  A stopper cylindrical portion 23 as a protruding portion is integrally provided at the outer peripheral end of the wheel washer 22, and a boss portion 24 as a cylindrical portion is integrally provided at the inner peripheral end. The stopper cylindrical portion 23 and the boss portion 24 are each formed in a cylindrical wall shape coaxial with the wheel washer 22, and protrude in the axial direction toward the tip end side of the spindle 17 with respect to the wheel washer 22. The protruding height of the boss portion 24 from the wheel washer 22 is set to be higher than the protruding height of the stopper cylindrical portion 23 from the wheel washer 22, and the boss portion 24 is supported by the male screw portion 17a of the spindle 17 on the inner peripheral surface thereof. Has been.

  A ring rubber 25 as an elastic member is disposed inside an annular groove portion having a wheel washer 22 formed between the stopper cylindrical portion 23 and the boss portion 24 as a bottom. The ring rubber 25 is formed in an annular shape having a rectangular cross section by a rubber material. Further, the axial thickness dimension of the ring rubber 25 is set to be larger than the axial height dimension of the stopper cylindrical portion 23, whereby the ring rubber 25 protrudes in the axial direction from the stopper cylindrical portion 23.

  The inner peripheral portion of the tip end portion of the stopper cylindrical portion 23 is notched, and a notch portion 23a is formed. The notch 23a is formed to smooth a portion that contacts the stopper cylindrical portion 23 when the ring rubber 25 is compressed. For this reason, when the ring rubber 25 deform | transforms and contacts the notch part 23a, it can be made hard to produce a crack in the ring rubber 25. FIG.

  The diamond wheel 12 is mounted on the spindle 17 by fitting a mounting hole 12c provided in the axis thereof to the outer peripheral surface of the boss portion 24 by a clearance fit. When the substrate 12 a is mounted on the spindle 17, the ring rubber 25 is disposed between the substrate 12 a and the wheel washer 22.

  In order to fix the wheel washer 22 and the boss portion 24 to the spindle 17 and to hold the diamond grinding wheel 12 between the wheel washer 22, a pressing plate 26 is integrally formed at the tip of the male screw portion 17 a of the spindle 17. A lock nut 27 is screwed. The lock nut 27 includes four concave portions 27a arranged at equal intervals in the circumferential direction, and convex portions of a dedicated jig (not shown) are engaged with these concave portions 27a. The lock nut 27 is screwed into the male screw portion 17a by this dedicated jig until it abuts on the boss portion 24, and the wheel washer 22 is fixed to the spindle 17 by sandwiching the boss portion 24 between the lock nut 27 and the seat surface 17b. . As described above, the holding plate 26 provided integrally with the lock nut 27 is disposed with a boss portion 24 as a cylindrical portion as a spacer and spaced apart from the wheel washer 22 in the axial direction.

  In the present embodiment, the boss portion 24 as a cylindrical portion is formed integrally with the wheel washer 22, but not limited to this, the boss portion 24 as a cylindrical portion is formed integrally with the lock nut 27. Alternatively, the wheel washer 22 and the lock nut 27 may be formed as separate parts and sandwiched between the wheel washer 22 and the lock nut 27.

  When the lock nut 27 is fastened to the male screw portion 17a, the substrate 12a is pushed by the lock nut 27, and the ring rubber 25 is sandwiched between the substrate 12a and the wheel washer 22 and held in a compressed state.

As shown in FIG. 2, the wheel washer 22 is provided with four support holes 22b penetrating in the axial direction of the wheel washer 22 at regular intervals in the circumferential direction. A spring pin 28 as a guide member (pin member) is inserted into each of the support holes 22b.
These spring pins 28 are columnar members extending in the direction of the spindle 17 and are formed in a C-shaped cross section whose outer diameter is slightly larger than the inner diameter of the support hole 22b. It is press-fitted into the support hole 22b while shrinking. Thereby, each spring pin 28 is supported in the state fixed to the wheel washer 22 in the end.

  Four support holes 26 a facing in the axial direction corresponding to the support holes 22 b of the wheel washer 22 are provided at equal intervals in the circumferential direction in the holding plate 26 portion of the lock nut 27. The other end of each spring pin 28 whose one end is supported by the wheel washer 22 is inserted into a corresponding support hole 26 a provided in the holding plate 26 portion of the lock nut 27. The inner diameter dimension of the support hole 26a is set slightly smaller than the outer diameter dimension of the spring pin 28, and the other end of each spring pin 28 is press-fitted into the corresponding support hole 26a while reducing the outer diameter. Thereby, each spring pin 28 is supported in the state fixed to the part of the pressing plate 26 of the lock nut 27 at the other end. The axial direction of the spring pin 28 supported at both ends by the wheel washer 22 and the holding plate 26 portion of the lock nut 27 is parallel to the spindle 17.

  Thus, in this embodiment, the lock nut 27 has a structure in which the pressing plate 26 that supports the spring pin 28 is integrally formed, and also functions as the pressing plate 26.

  On the other hand, on the substrate 12a of the diamond grindstone wheel 12, four insertion holes 12d facing in the axial direction corresponding to the spring pins 28 are arranged in the circumferential direction at equal intervals. Similarly, the ring rubber 25 is provided with four insertion holes 25a facing in the axial direction corresponding to the spring pins 28 and arranged at equal intervals in the circumferential direction.

  Each spring pin 28 having both ends fixed (supported) to the wheel washer 22 and the holding plate 26 portion of the lock nut 27 is inserted into the corresponding insertion hole 12d to penetrate the substrate 12a, and the corresponding insertion hole. The ring rubber 25 is inserted through the ring rubber 25a. The inner diameters of these insertion holes 12d and 25a are set to be slightly larger than the outer diameters of the spring pins 28 in a state where they are press-fitted into the support holes 22b and 26a of the wheel washer 22 and the lock nut 27. That is, the substrate 12 a and the ring rubber 25 are in a state of being fitted into the spring pins 28 so as to be movable in the axial direction with respect to the spring pins 28. Further, each spring pin 28 supported by the wheel washer 22 is inserted into the insertion hole 12d of the substrate 12a, whereby the substrate 12a is prevented from rotating around the wheel washer 22 by the spring pin 28. In other words, the spring pin 28 also functions as a stop for the diamond washer wheel 12 around the wheel washer 22.

With such a configuration, the diamond grinding wheel 12 is supported by the wheel washer 22 via the ring rubber 25, so that vibration due to an impact applied to the diamond grinding wheel 12 during the grinding operation is caused by elastic deformation of the ring rubber 25. Can be absorbed.
Therefore, it is possible to reduce the vibration transmitted to the operator during the grinding operation and improve the workability.

  Further, since the spring pin 28 supported at both ends by the press plate 26 of the wheel washer 22 and the lock nut 27 is inserted through the substrate 12a and the ring rubber 25, the occurrence of permanent deformation of the ring rubber 25 is suppressed. Thus, the vibration suppressing effect of the ring rubber 25 can be maintained over a long period of time. In the following, based on FIGS. 5 and 6, the mounting structure 21 according to the present invention prevents the diamond rubber wheel 12 from being inclined during the grinding operation, so that excessive deformation of the ring rubber 25 is prevented. The point that the permanent deformation is suppressed will be described.

  As shown in FIG. 4, in a no-load state where the diamond grinding wheel 12 is not in contact with the work material, the substrate 12a is pressed by the ring rubber 25, and a portion of the holding plate 26 of the lock nut 27 at one end surface in the axial direction thereof. Abut. In addition, a gap is formed between the substrate 12 a of the diamond grinding wheel 12 and the tip of the stopper cylindrical portion 23.

  As shown in FIG. 5 (a), when the diamond grinding wheel 12 is pressed in parallel with the surface of the work material and the grinding operation is performed in a state of contact with the entire surface, the diamond wheel 12 is pressed against the work material. It moves in parallel along the spindle 17 due to the reaction force of the load, and a gap is generated between the substrate 12a and the portion of the holding plate 26 of the lock nut 27.

  At this time, the ring rubber 25 disposed between the wheel washer 22 and the substrate 12a is pressed by the substrate 12a and compressed in the axial direction, but the diamond wheel 12 is kept parallel to the surface of the work material. Since the ring rubber 25 moves in the axial direction as it is, the entire ring rubber 25 is uniformly pressed by the substrate 12a. Therefore, only a part of the ring rubber 25 is not greatly deformed.

  When the diamond wheel 12 is in contact with the entire surface and the pressing load is excessive, the substrate 12a moves further away from the lock nut 27 than the position shown in FIG. The rubber 25 is further compressed.

  In this case, when the pressing force of the diamond grindstone wheel 12 exceeds a predetermined value, the substrate 12a comes into contact with the tip of the stopper cylindrical portion 23 provided in the wheel washer 22, as shown in FIG. Further axial movement of the diamond wheel 12 is restricted. Therefore, even if an excessive pressing load is applied to the diamond wheel 12 during the grinding operation, excessive compression (deformation) of the ring rubber 25 is prevented. Thus, since excessive deformation of the ring rubber 25 is prevented, permanent deformation of the ring rubber 25 is suppressed.

  On the other hand, when a grinding operation is performed in a state where only a part of the surface of the diamond grinding wheel 12 is pressed against the work material, the work is performed from the work material to the diamond grinding wheel 12 with respect to the axial direction of the spindle 17. A reaction force in an inclined direction is applied.

  However, in the mounting structure 21 of the present invention, the mounting hole 12c of the substrate 12a is fitted into the boss portion 24 of the wheel washer 22, and the spring pins 28 that are supported at both ends by the holding plate 26 portion of the lock nut 27 are mounted on the substrate. Since it is inserted into 12a with the gap fitted, the inclination of the diamond grinding wheel 12 can be prevented.

  When a reaction force inclined with respect to the axial direction of the spindle 17 is applied, the substrate 12a of the diamond grinding wheel 12 moves in a direction away from the lock nut 27, and clearance fitting between the mounting hole 12c and the insertion hole 12d is performed. Therefore, it moves in the radial direction with respect to the spindle 17. When the substrate 12a moves in the radial direction, the inner peripheral surface of the mounting hole 12c contacts the outer peripheral surface of the boss portion 24 of the wheel washer 22, and the inner peripheral surface of each insertion hole 12d contacts the outer peripheral surface of the corresponding spring pin 28. Abut. In this way, the diamond grinding wheel 12 that has come into contact with the work material is supported at a plurality of points of the boss portion 24 and the spring pins 28, so that the tilt with respect to the spindle 17 is prevented.

  When the inclination of the diamond grinding wheel 12 is prevented, the substrate 12a does not excessively deform only a part of the ring rubber 25, so that excessive deformation of the ring rubber 25 is prevented. Thus, even when the diamond grindstone wheel 12 hits the work piece, excessive deformation of the ring rubber 25 is prevented, so that permanent deformation of the ring rubber 25 is suppressed.

  Even when the diamond grinding wheel 12 hits the work piece, if the pressing load becomes excessive, the tip of the stopper cylindrical portion 23 is applied to the tip of the stopper cylindrical portion 23 as shown in FIG. The substrate 12a abuts, and the movement of the diamond grindstone wheel 12, that is, the substrate 12a is restricted, and excessive compression (deformation) of the ring rubber 25 is prevented.

  As described above, in the mounting structure 21 of the present invention, the mounting hole 12c of the substrate 12a is fitted into the boss portion 24 of the wheel washer 22, and both ends are supported by the wheel washer 22 and the holding plate 26 portion of the lock nut 27. Since the spring pin 28 is inserted into the substrate 12a with a gap fitted, the inclination of the diamond grinding wheel 12 is suppressed, thereby preventing only a part of the ring rubber 25 from being deformed excessively. The permanent deformation of the ring rubber 25 can be suppressed. Therefore, in the mounting structure 21 of the present invention, permanent deformation of the ring rubber 25 can be suppressed, and the vibration suppressing effect by the ring rubber 25 of the mounting structure 21 can be maintained for a long period of time.

  In the mounting structure 21 of the present invention, since the holding plate 26 that supports the spring pin 28 is formed integrally with the lock nut 27, the number of parts can be reduced and the manufacturing cost of the mounting structure 21 can be reduced. it can.

  Further, in the structure in which the pressing plate 26 is formed integrally with the lock nut 27, the mounting structure 21 can be unitized with the mounting structure 21 attached to the substrate 12a. That is, by press-fitting the spring pin 28, the wheel washer 22 and the lock nut 27 can be held in an assembled state in which the substrate 12a and the ring rubber 25 are sandwiched therebetween. As a result, the mounting structure 21 is attached in advance to the substrate 12a of the diamond wheel 12 and unitized, and when the diamond wheel 12 is mounted on the disc grinder 11, the mounting structure 21 is screwed into the spindle 17 for easy mounting. It can be set as the structure which can work.

  In the mounting structure 21 of the present invention, the spring pin 28 is used as the pin member. Therefore, the mounting operation of the spring pin 28 to the support hole 22b of the wheel washer 22 and the support hole 26a of the pressing plate 26, the substrate 12a and the ring The work of penetrating the rubber 25 through the insertion holes 12d and 25a can be facilitated, and the manufacturing cost of the mounting structure 21 can be reduced.

  Next, based on FIG. 6, a comparison is made of a mounting structure 31 in which both ends are supported by the wheel washer 22 and the holding plate 26 portion of the lock nut 27 and the spring pin 28 penetrating the substrate 12 a and the ring rubber 25 is not provided. This will be described as an example. In FIG. 6, members corresponding to those described above are denoted by the same reference numerals.

  FIG. 6A shows a no-load state of the mounting structure 31 of the comparative example. A sub washer 32 is mounted on the spindle 17 and the sub washer 32 is in contact with the seat surface 17b. The wheel washer 22 is disposed so as to overlap the sub washer 32 in the axial direction, and is mounted on the spindle 17.

  A boss 24 is integrally provided at the inner peripheral end of the wheel washer 22, and a rotation stop means 33 for the diamond grindstone wheel 12 is provided on the outer peripheral surface of the boss 24.

  The diamond wheel 12 is mounted on the boss portion 24 of the wheel washer 22 in the mounting hole 12c provided in the axis of the substrate 12a. An anti-rotation means 34 is provided on the inner peripheral surface of the mounting hole 12c of the substrate 12a. When the diamond grindstone wheel 12 is mounted on the boss portion 24, the anti-rotation means 34 is provided on the outer peripheral surface of the boss portion 24. It fits loosely into the rotation stop means 33. Splines are used as the rotation stop means 33 and 34, and the diamond grindstone wheel 12 can be moved in the axial direction with respect to the boss portion 24 by the rotation stop means 33 and 34, but in the rotation direction. It is in a stopped state.

  The ring rubber 25 is disposed between the wheel washer 22 and the substrate 12a.

  The wheel washer 22 is fixed to the spindle 17 by being sandwiched between the sub washer 32 by a lock nut 27 screwed to the male threaded portion 17 a of the spindle 17. When the lock nut 27 is tightened, the substrate 12a is pushed by the lock nut 27, and the ring rubber 25 is sandwiched between the substrate 12a and the wheel washer 22 and held in a compressed state.

  In the mounting structure 31 shown as a comparative example, as shown in FIG. 6 (b), when the diamond grinding wheel 12 hits the entire work surface, the diamond grinding wheel 12 moves in the axial direction, and diamond Vibration due to an impact applied to the grinding wheel 12 can be absorbed by elastic deformation of the ring rubber 25.

  However, as shown in FIG. 6C, the substrate 12 a has a contact portion between the inner peripheral surface and the outer peripheral surface of the boss portion 24 as a fulcrum by the reaction force inclined with respect to the axial direction of the spindle 17. As a result, the lock nut 27 is inclined with respect to the spindle 17 until it hits the lower surface.

  Thus, in the mounting structure 31 of the comparative example, when the diamond grindstone wheel 12 hits the work piece, the substrate 12a is inclined, and excessive deformation of the ring rubber 25 cannot be prevented. Deformation occurs early. As a result, the backlash between the substrate 12a and the ring rubber 25 is increased, the vibration suppression effect by the ring rubber 25 is reduced at an early stage, and problems such as fluttering of the diamond grindstone wheel 12 occur during the grinding operation. .

  FIG. 7 is a cross-sectional view showing a modification of the mounting structure shown in FIG.

  In the case shown in FIG. 4, the holding plate 26 that supports the spring pin 28 is formed integrally with the lock nut 27. On the other hand, in the modification shown in FIG. 7, the pressing plate 26 is formed separately from the lock nut 27.

  In this case, the holding plate 26 is attached to the male screw portion 17a of the spindle 17 by a clearance fit, and is fixed between the lock nut 27 and the boss portion 24 which are screwed to the male screw portion 17a. In the modified example having such a structure, the position of the pressing plate 26 in the rotation direction can be freely set regardless of the degree of screwing of the lock nut 27 into the male screw portion 17a. The effect that the positioning of the support hole 26a of the pressing plate 26 with respect to the support hole 22b of the wheel washer 22 becomes easy is obtained.

  It goes without saying that 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, in the above-described embodiment, an electric tool using the electric motor 14 as a driving source is described as a power tool to which the present invention is applied. However, the invention is not limited thereto, and compressed air (air motor) is used as a driving source. The mounting structure 21 of the present invention may be applied to a power tool using another drive source (motor) such as an air tool or an engine tool using an engine as a drive source.

  In the embodiment, the spring pin 28 is used as the guide member (pin member). However, the present invention is not limited to this. For example, a round bar is used as the pin member, and the round bar is used as the wheel washer 22 or the holding plate 26. It is good also as a structure press-fitted in the support holes 22b and 26a. The guide member (pin member) is not limited to a circular cross section, and the cross sectional shape is not limited.

  Furthermore, in the above-described embodiment, the ring rubber 25 formed of a rubber material is used as the elastic member. However, the present invention is not limited to this, and the elastic member is formed of, for example, urethane or sponge material. You may make it use a thing. In addition, the shape of the elastic member is not limited to an annular shape having a rectangular cross section, but may be a shape that is disposed between the wheel washer 22 and the substrate 12a, such as an annular shape having a circular cross section, and can absorb vibration of the substrate 12a. Any other shape may be used.

  Furthermore, in the above-described embodiment, a diamond grindstone wheel is used as a tip tool. However, the present invention is not limited to this, and for example, the present invention is used to attach other tip tools such as a resinoid grindstone, a sanding disk, a wire brush, and a polisher. The mounting structure 21 may be adopted.

11 Disc grinder (power tool)
12 Diamond wheel (tip tool)
12a Substrate 12b Diamond grinding wheel 12c Mounting hole 12d Insertion hole 12e Through hole 13 Body case 14 Electric motor 15 Power cord 16 Gear case 17 Spindle (output shaft)
17a Male thread part 17b Bearing surface 18a, 18b Bearing 19a, 19b Bevel gear 21 Tip tool mounting structure 22 Wheel washer 22a Through hole 22b Support hole 23 Stopper cylindrical part (protrusion part)
23a Notch 24 Boss (cylindrical part)
25 Ring rubber (elastic member)
25a Insertion hole 26 Holding plate 26a Support hole 27 Lock nut 27a Recess 28 Spring pin (pin member)
31 Mounting structure 32 Sub washer 33, 34 Rotation stop means

Claims (9)

A motor as a power source;
A spindle driven to rotate by the motor;
An elastic member held by the spindle;
A tip tool connected to the elastic member;
A power tool comprising: a guide member for guiding the tip tool in the spindle direction. A wheel washer connected to the spindle;
The elastic member is held by the wheel washer;
The guide member is a columnar member extending in the spindle direction,
The power tool according to claim 1, wherein the columnar member penetrates the elastic member and the tip tool. The spindle is formed with a male screw part,
A lock nut having a female thread portion engaged with the male thread portion;
The power tool according to claim 1, wherein the columnar member is connected to the lock nut.   The power tool according to claim 3, wherein the wheel washer, the elastic member, the tip tool, the columnar member, and the lock nut are integrally fixed by the columnar member.   The power tool according to any one of claims 2 to 4, wherein a plurality of the columnar members are provided around the spindle. The elastic member is sandwiched between the wheel washer and the tip tool,
The wheel washer has a protrusion extending in the tip tool direction,
The power tool according to any one of claims 2 to 5, wherein the protruding portion is configured to be able to contact the tip tool when the elastic member is deformed. A wheel type tip tool is a power tool attached to the output shaft,
A wheel washer mounted on the output shaft;
A holding plate attached to the output shaft at an axial interval with respect to the wheel washer;
A cylindrical portion provided on either the wheel washer or the pressing plate;
A substrate of the tip tool, which is disposed between the wheel washer and the pressing plate and is fitted to the cylindrical portion so as to be movable in the axial direction in an attachment hole provided in an axial center;
An elastic member disposed between the foil washer and the substrate;
A lock nut that is screwed to the tip of the output shaft, and that fixes the wheel washer, the pressing plate, and the cylindrical portion to the output shaft;
A power tool comprising: a pin member having one end supported by the wheel washer and the other end supported by the pressing plate, and penetrating the substrate and the elastic member.   The power tool according to claim 7, wherein the pressing plate and the lock nut are integrally formed.   The power tool according to claim 7 or 8, wherein the pin member is a spring pin.