Rotating tool

Abstract

To provide a rotating tool which is improved in loose-stopping structure.SOLUTION: A rotating tool comprises a spindle, a female screw member, and a loose-stopping member. The spindle has a lower end part constituted as a male screw part and a flange part protruding to outside in a radial direction of the spindle, above the female screw part. The female screw member is detachably screwed to the male screw part. The loose-stopping member is fitted into a circumference of the spindle, above the male screw part. A lower surface of the flange part of the spindle includes a first inclining surface that extends in a circumferential direction around a driving shaft and inclines downward as going in a first direction. The loose-stop member includes an annular base part having a second inclining surface that slidably contacts the first inclining surface of the flange part, and a peripheral wall part protruding upward along an outer edge portion of the base part, which contacts a side surface of the flange part when the spindle rotates and receives rotation driving force. The peripheral wall part is provided only on a portion of the outer edge portion of the base part.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a rotary tool configured to rotationally drive a tip tool.

Background Art

[0002] A rotary tool (e.g., a grinder) rotationally drives a tip tool removably held on a spindle. The tip tool is fixed to the spindle, for example, by tightening a nut on the spindle. The nut may loosen when the rotation of the spindle suddenly stops. To address this problem, the grinder disclosed in Patent Document 1 includes a loosening prevention member. The loosening prevention member is configured to move toward the tip tool side by the action of inclined surfaces (cam surfaces) respectively provided on the flange portion of the spindle and the loosening prevention member when the rotation of the spindle suddenly stops.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above grinder, the flange portion of the spindle is fitted into a fitting recess provided in the loosening prevention member with a clearance. The lower surface of the flange portion of the spindle is an inclined surface that abuts against the inclined surface of the bottom surface of the fitting recess. In such a configuration, dust may accumulate in the fitting recess, resulting in insufficient movement of the loosening prevention member due to the inclined surface and potentially preventing the full loosening prevention effect from being achieved.

[0005] In view of the above situation, one non-limiting object of the present disclosure is to provide an improvement in the loosening prevention structure in a rotary tool.

Means for Solving the Problems

[0006] According to one non - limiting aspect of the present disclosure, a rotary tool is provided that includes a spindle, a female screw member, and a locking member. The spindle is configured to be rotationally driven in a first direction around a drive shaft that defines the vertical direction of the rotary tool. The spindle has a lower end portion formed as a male screw portion and a flange portion that protrudes radially outward of the spindle above the male screw portion. The female screw member is removably screwed onto the male screw portion. The locking member is annular and is fitted around the spindle above the male screw portion. The locking member is configured to rotate integrally with the spindle during rotation of the spindle in the first direction, and in response to the rotation stop of the spindle, to displace downward while rotating in the first direction with respect to the spindle, thereby suppressing loosening of the female screw member.

[0007] The lower surface of the flange portion of the spindle includes a first inclined surface. The first inclined surface extends in the circumferential direction around the drive shaft and is inclined downward as it goes in the first direction. The locking member includes a base portion and a peripheral wall portion. The base portion is annular and is disposed below the flange portion. Further, the base portion has a second inclined surface that slidably abuts against the first inclined surface of the flange portion. The peripheral wall portion protrudes upward along the outer edge portion of the base portion. The peripheral wall portion is configured to abut against the side surface of the flange portion during rotation of the spindle to receive a rotational driving force. Further, the peripheral wall portion is provided only at a part of the outer edge portion of the base portion.

[0008] In the rotary tool of this aspect, when the spindle that has been rotating in the first direction stops rotating, due to the action of the first inclined surface of the flange portion of the spindle and the second inclined surface of the locking member, the locking member rotates in the first direction with respect to the spindle and displaces downward. As a result, a force that presses the female screw member downward acts on the female screw member, thereby suppressing loosening of the female screw member.

[0009] In addition, the anti-loosening member is provided with a peripheral wall portion that protrudes upward from the base portion in order to receive the rotational driving force from the spindle. However, the peripheral wall portion is provided only in a part, not over the entire circumference of the outer edge portion of the base portion. That is, there is an opening (gap, space) without the peripheral wall portion on the radially outer side of the flange portion. For this reason, compared with the configuration in which the peripheral wall portion is provided over the entire circumference of the outer edge portion of the base portion, dust is less likely to accumulate in the region (space) radially inside the peripheral wall portion. Further, even if dust enters this region, when the anti-loosening member rotates integrally with the spindle, the dust can be effectively discharged by centrifugal force through the gap. Thereby, it is possible to reduce the possibility that dust enters between the first inclined surface and the second inclined surface, preventing the displacement of the anti-loosening member and reducing the anti-loosening effect.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0011] In a non-limiting embodiment of the present disclosure, the base portion may have a passage that extends from the radially inner end to the radially outer end of the base portion below the flange portion. According to this embodiment, even if dust enters the region radially inside the peripheral wall portion, the dust can be discharged not only from the opening on the radially outer side of the flange portion but also from the passage below the flange portion.

[0012] In addition to or instead of the above-described embodiment, the passage may be provided adjacent to an end of the second inclined surface on the side opposite to the first direction in the circumferential direction. The second inclined surface corresponds to the first inclined surface and slopes downward as it goes in the first direction. Therefore, the end of the second inclined surface on the side opposite to the first direction is at the uppermost position in the vertical direction among the second inclined surfaces. Thus, by providing the passage adjacent to this end, the vertical dimension of the passage can be maximized.

[0013] In addition to or instead of the above-described embodiment, in the vertical direction, the upper end of the peripheral wall portion of the anti-loosening member may be below the upper end of the flange portion of the spindle. Further, the upper end of the anti-loosening member may be at the same position as or below the center of the flange portion in the vertical direction. According to these embodiments, an anti-loosening member in which dust is less likely to accumulate can be realized.

[0014] In addition to or instead of the above-described embodiment, the peripheral wall portion may include a rotation transmission portion and an extension portion. The rotation transmission portion may have a rotation transmission surface configured to receive the rotational driving force from the spindle. The extension portion may extend in the second direction from an end of the rotation transmission portion on the second direction side opposite to the first direction, radially outside the flange portion. According to this embodiment, the extension portion can reduce the possibility of dust entering between the rotation transmission surface and the side surface of the flange portion from the radially outer side of the flange portion.

[0015] In addition to or instead of the above-described embodiment, the peripheral wall portion may further include a stopper portion. The stopper portion may have a stopper surface configured to contact the side surface of the flange portion to restrict the rotation of the loosening prevention member when the loosening prevention member rotates in the first direction with respect to the spindle. The extending portion may extend along the outer edge portion of the base from at least a virtual first plane including the rotation transmission surface to a virtual second plane including the stopper surface. The flange portion can rotate between a position where the side surface contacts the rotation transmission surface and a position where the side surface contacts the stopper surface. Therefore, the region between the first plane and the second plane corresponds to the gap that can occur between the side surface of the flange portion and the rotation transmission surface. According to this embodiment, since the extending portion corresponds to the entire gap, the entry of dust can be more effectively prevented.

[0016] In addition to or instead of the above-described embodiment, the rotary tool may further include an annular member removably disposed around the spindle between the loosening prevention member and the male screw portion. The annular member may be configured to engage with the loosening prevention member and rotate integrally with the loosening prevention member. A recess for engaging with the annular member may be formed in the lower portion of the rotation transmission portion of the base portion. The extending portion may extend in the second direction beyond the end on the second direction side of the recess. According to this embodiment, in the vertical direction, since the recess is provided by utilizing the portion where the height of the rotation transmission portion is added to the base portion, it is possible to provide the recess necessary for engagement with the annular member while suppressing the vertical height of the loosening prevention member. Further, by providing the extending portion, it is possible to avoid thinning of the portion where the recess is formed and ensure sufficient strength while suppressing the vertical height of the entire loosening prevention member.

[0017] In addition to or instead of the above-described embodiments, the rotary tool may further include an annular elastic body attached to an annular groove formed on the outer peripheral surface of the spindle. The anti-loosening member may be held by the elastic body so as to be rotatable about the drive shaft with respect to the spindle and movable in the vertical direction as the elastic body elastically deforms. According to this embodiment, a space-saving and reasonable holding structure for the anti-loosening member is realized by using an elastic body with a simple structure.

[0018] Hereinafter, with reference to the drawings, representative and non-limiting embodiments of the present disclosure will be specifically described. In the following embodiments, as an example of the rotary tool according to the present disclosure, a hand-held electric disk grinder 1 (hereinafter simply referred to as grinder 1) will be given.

[0019] First, the schematic configuration of the grinder 1 will be described. As shown in FIG. 1, the grinder 1 includes a motor 21, a spindle 3 operably connected to the output shaft 215 of the motor 21, and a housing 10 that houses the motor 21 and the spindle 3. The housing 10 is a long hollow body that forms the outer contour of the grinder 1. The motor 21 is arranged such that the rotation axis RX of the output shaft 215 extends substantially parallel to the long axis of the housing 10. The spindle 3 is arranged inside one end of the housing 10 in the long axis direction. The spindle 3 is rotatably supported in the housing 10 about the drive shaft DX. The drive shaft DX intersects (specifically, is substantially orthogonal to) the rotation axis RX of the output shaft 215. From this, the grinder is also referred to as an angle grinder.

[0020] One axial end of the spindle 3 is exposed to the outside from the housing 10. The tip tool 91 is removably attached to this one end of the spindle 3. Note that, as the tip tool 91 attachable to the grinder 1, for example, a grinding wheel, a cutting wheel, a blade, a brush, etc. are prepared. The user selects an appropriate tip tool 91 according to the desired machining operation and attaches it to the grinder 1. As the spindle 3 is rotationally driven around the drive shaft DX by the motor 21, the tip tool 91 is rotated and the machining operation on the workpiece is performed. The grinder 1 can perform machining operations such as grinding, polishing, and cutting on the workpiece according to the type of the tip tool 91. Note that the tip tool 91 is partially covered by a wheel cover 92 attached to the housing 10.

[0021] Hereinafter, the detailed configuration of the grinder 1 will be described. In the following, for convenience of explanation, the extending direction of the drive shaft DX is defined as the vertical direction of the grinder 1. In the vertical direction, one end side of the spindle 3 to which the tip tool 91 is attached is defined as the lower side of the grinder 1, and the opposite side is defined as the upper side of the grinder 1. The extending direction of the rotation axis RX of the output shaft 215 is defined as the front-rear direction of the grinder 1. In the front-rear direction, the side on which the spindle 3 is disposed is defined as the front side of the grinder 1, and the opposite side is defined as the rear side of the grinder 1. The direction orthogonal to the vertical direction and the front-rear direction is defined as the left-right direction of the grinder 1. Further, an arbitrary direction orthogonal to the drive shaft DX is defined as the radial direction of the spindle 3, the direction away from the drive shaft DX is defined as the radially outer direction, and the direction approaching the drive shaft DX is defined as the radially inner direction.

[0022] As shown in FIG. 1, the housing 10 includes a motor housing 11 and a gear housing 15 connected to the front end of the motor housing 11.

[0023] The motor housing 11 is a long cylindrical housing extending in the front-rear direction. The motor housing 11 is configured to also function as a gripping portion to be gripped by a user. The motor housing 11 houses the motor 21 and the switch 22. The output shaft 215 of the motor 21 extends in the front-rear direction. The front end portion and the rear end portion of the output shaft 215 are supported by bearings, respectively. The switch 22 is disposed behind the motor 21. The switch 22 is operably connected to a switch knob (not shown). The switch knob is disposed outside the motor housing 11 and is moved between an off position and an on position in response to a manual operation of the user. The switch 22 is turned on and off in response to the movement of the switch knob. The motor 21 is driven while the switch 22 is on.

[0024] In this embodiment, the grinder 1 operates with electric power supplied from an external AC power source via a power cord 29 extending from the rear end portion of the motor housing 11. However, the grinder 1 may be configured to operate with electric power supplied from a removably attached rechargeable battery.

[0025] Also, as shown in FIG. 2, a mechanical brake device 25 is housed in the motor housing 11. More specifically, the brake device 25 is disposed in front of the motor 21 within the motor housing 11. The brake device 25 is a friction brake device and includes a brake plate 251, a brake member 253, and a biasing spring 255. The brake plate 251 is disk-shaped and is fixed to the output shaft 215 of the motor 21 and rotates integrally with the output shaft 215. The brake member 253 is a disk-shaped member having a brake material fixed to its rear surface and is disposed on the front side of the brake plate 251 so as to face the brake plate 251. The biasing spring 255 is disposed on the front side of the brake member 253 and biases the brake member 253 rearward toward the brake plate 251.

[0026] The brake member 253 is configured to move in response to the movement of the switch knob. More specifically, while the switch knob is in the off position, the brake member 253 is strongly pressed against the brake plate 251 by the biasing force of the biasing spring 255. When the user moves the switch knob to the on position, the brake member 253 moves forward away from the brake plate 251 against the biasing force of the biasing spring 255, allowing the rotation of the output shaft 215 of the motor 21. On the other hand, when the user moves the switch knob to the off position, the drive of the motor 21 is stopped. Along with this, the brake member 253 is strongly pressed against the brake plate 251 by the biasing force of the biasing spring 255, braking the output shaft 215 and the spindle 3 via the brake plate 251.

[0027] As shown in FIG. 2, the spindle 3 is accommodated within the gear housing 15. The spindle 3 is a long, round bar-shaped shaft (cylindrical member). The spindle 3 is arranged within the gear housing 15 so as to extend in the vertical direction and is rotatably supported about the drive shaft DX by a plurality of bearings. A driven bevel gear 38 is fixed to the upper portion of the spindle 3. The front end portion of the output shaft 215 of the motor 21 projects into the gear housing 15, and a drive bevel gear 216 that meshes with the driven bevel gear 38 is fixed to this portion.

[0028] With such a configuration, with the drive of the motor 21, the rotation of the output shaft 215 is transmitted to the spindle 3, and the spindle 3 is rotationally driven. Since the grinder 1 is a rotary tool that rotationally drives the tip tool 91 only in one direction, the spindle 3 is rotationally driven only in a predetermined one direction about the drive shaft DX. Specifically, the rotation direction RD (see FIG. 3) of the spindle 3 is clockwise when viewed from above.

[0029] The lower end of the spindle 3 protrudes downward from an opening provided at the lower end of the gear housing 15 and is exposed outside the housing 10. The lower end of the spindle 3 is configured as an external thread portion 31. The external thread portion 31 is a portion where threads are formed on the outer peripheral surface and is provided within a predetermined range from the lower end of the spindle 3. A lock nut 55 for fixing the tip tool 91 to the spindle 3 is removably screwed onto the external thread portion 31.

[0030] As shown in FIGS. 2 to 4, the spindle 3 has a flange portion 33 that protrudes radially outward. The flange portion 33 is spaced apart from the external thread portion 31 and is provided above the external thread portion 31. The flange portion 33 of the present embodiment includes a pair (two) of protruding portions 331 that protrude radially outward from the round bar-shaped portion of the spindle 3. The two protruding portions 331 protrude in opposite directions along a straight line orthogonal to the drive shaft DX. In the present embodiment, the flange portion 33 is integrally formed with the spindle 3, but the flange portion 33 may be formed as a separate member from the spindle 3 and fixed to the spindle 3.

[0031] Each of the two protruding portions 331 of the flange portion 33 has side surfaces 333 that are substantially parallel to each other and arcuate end surfaces. The side surfaces 333 are substantially parallel to the plane including the drive shaft DX. Also, the lower surface of each of the protruding portions 331 is a first inclined surface 336. The first inclined surface 336 extends in an arc shape along the circumferential direction around the drive shaft DX. The first inclined surface 336 is inclined at a predetermined angle with respect to the plane orthogonal to the drive shaft DX. More specifically, the first inclined surface 336 inclines downward as it goes in the rotation direction RD of the spindle 3. The angle formed by the plane orthogonal to the drive shaft DX and the first inclined surface 336 (hereinafter simply referred to as the inclination angle of the first inclined surface 336) is set to be larger than the lead angle of the threads of the external thread portion 31.

[0032] As shown in FIGS. 2 and 5, a loosening prevention member 4 and an inner flange 51 are disposed between the external thread portion 31 and the flange portion 33.

[0033] The anti-loosening member 4 is generally an annular (short cylindrical) member as a whole. The anti-loosening member 4 is inserted into the spindle 3 between the flange portion 33 and the male screw portion 31 (inner flange 51) in the vertical direction. The anti-loosening member 4 is configured to rotate integrally with the spindle 3 upon receiving the transmission of the rotational driving force from the flange portion 33 when the spindle 3 is rotationally driven. Further, the anti-loosening member 4 is configured to cooperate with the flange portion 33 to prevent loosening of the lock nut 55 in response to the rotation of the spindle 3 being stopped.

[0034] More specifically, as shown in FIGS. 3 to 7, the anti-loosening member 4 includes a generally disk-shaped base portion 41 having an insertion hole 410, and two peripheral wall portions 45 protruding upward from the outer edge portion of the base portion 41.

[0035] The two peripheral wall portions 45 face each other in the diameter direction of the base portion 41 on the base portion 41. Therefore, in the circumferential direction of the anti-loosening member 4, two openings (gaps, spaces) 401 are provided between the two peripheral wall portions 45. In other words, the two peripheral wall portions 45 and the two openings 401 are alternately arranged along the outer edge portion of the base portion 41. Further, the two peripheral wall portions 45 are in a point-symmetrical relationship about the drive shaft DX in a plan view. In the region (space) 450 between the two peripheral wall portions 45 that face each other in the diameter direction, the flange portion 33 of the spindle 3 is arranged in a state where there is play in the circumferential direction (see FIG. 7). That is, the flange portion 33 is rotatable by a predetermined angle around the drive shaft DX within the region 450. Note that the region 450 may be referred to as the region radially inside the peripheral wall portion 45.

[0036] Each of the peripheral wall portions 45 includes a rotation transmission portion 452, a stopper portion 454, and an extension portion 456.

[0037] The rotation transmission part 452 has a rotation transmission surface 451. The rotation transmission surface 451 is a part of the inner surface of the peripheral wall part 45 that is configured to contact the side surface 333 of the flange part 33 (protrusion 331) when the spindle 3 is rotationally driven in the rotation direction RD and receive the transmission of rotational power from the spindle 3 (see the solid line in FIG. 7). Note that the rotation transmission surface 451 is a flat surface.

[0038] The stopper part 454 has a stopper surface 453. The stopper surface 453 is a part of the inner surface of the peripheral wall part 45 that can contact the side surface 333 of the flange part 33 (protrusion 331) to restrict the rotation of the anti-loosening member 4 when the anti-loosening member 4 rotates in the rotation direction RD with respect to the spindle 3 (see the two-dot chain line in FIG. 7). Note that the stopper surface 453 is a flat surface. In this embodiment, the stopper part 454 (stopper surface 453) is directly connected to the end of the rotation transmission part 452 (rotation transmission surface 451) on the rotation direction RD side. However, there may be a part between the stopper part 454 (stopper surface 453) and the rotation transmission part 452 (rotation transmission surface 451) that does not contact the side surface 333 of the flange part 33 (and does not contribute to rotation transmission or rotation restriction).

[0039] The extension part 456 is a part that connects to the end of the rotation transmission part 452 on the side opposite to the rotation direction RD. The extension part 456 extends along the outer edge of the base part 41 on the radially outer side of the flange part 33. The extension part 456 extends from a virtual first plane P1 including the rotation transmission surface 451 to a position slightly exceeding a virtual second plane P2 including the stopper surface 453. As described above, the flange part 33 can rotate between a position where the side surface 333 contacts the rotation transmission surface 451 (the position shown by the solid line in FIG. 7) and a position where it contacts the stopper surface 453 (the position shown by the two-dot chain line in FIG. 7). Therefore, the region between the first plane P1 and the second plane P2 corresponds to the gap that can occur between the side surface 333 and the rotation transmission surface 451. The extension part 456 can be said to be a wall part that extends in the radially outer side of the gap and over a length in the circumferential direction of the gap corresponding to this gap.

[0040] The peripheral wall portion 45 is configured such that in the vertical direction, the upper end of the peripheral wall portion 45 is positioned below the upper end of the flange portion 33 of the spindle 3. More specifically, the upper end of the peripheral wall portion 45 is configured to be generally at the same level as or below the vertical center of the flange portion 33. Thus, generally the upper half of the flange portion 33 protrudes above the peripheral wall portion 45 (see Fig. 5).

[0041] The base portion 41 is provided with two wedge-shaped convex portions 411. The two convex portions 411 are arranged at positions respectively facing the lower surfaces of the two protruding portions 331 of the flange portion 33 disposed in the region 450. Each of the two convex portions 411 extends in an arc shape in the circumferential direction of the base portion 41. The upper surface of each of the two convex portions 411 is a second inclined surface 412 that inclines downward as it goes in the rotational direction RD of the spindle 3 at substantially the same angle as the first inclined surface 336. Thus, the second inclined surface 412 is slidably in contact with the first inclined surface 336 of the corresponding protruding portion 331 in a state where the flange portion 33 is disposed in the region 450.

[0042] Of the second inclined surface 412 (convex portion 411), the end 413 on the side opposite to the rotational direction RD (that is, the end where the protruding amount of the convex portion 411 is maximum) and the end 457 on the rotational direction RD side of the adjacent peripheral wall portion 45 are separated in the circumferential direction. That is, a gap is provided between the end 413 of the second inclined surface 412 (convex portion 411) and the end 457 of the peripheral wall portion 45. This gap functions as a passage 403 that extends from the radially inner end to the outer end of the base portion 41 below the flange portion 33 disposed in the region 450.

[0043] As shown in FIG. 2, the anti-loosening member 4 is connected to the spindle 3 by an O-ring 47 disposed between the spindle 3 and the base portion 41. The O-ring 47 is an annular elastic body (e.g., rubber). More specifically, the O-ring 47 is mounted and held in an annular groove 35 (see FIG. 4) formed on the outer periphery of the spindle 3 below the flange portion 33. Further, an annular recess 415 (see FIG. 4) surrounding the insertion hole 410 is provided at the lower portion of the base portion 41. The O-ring 47 is fitted into the recess 415 with a slight play in the radial direction.

[0044] With such a holding structure, the anti-loosening member 4 is rotatable about the drive shaft DX with respect to the spindle 3. Further, the anti-loosening member 4 is movable in the vertical direction with respect to the spindle 3 in response to the elastic deformation of the O-ring 47. Thus, in the present embodiment, a holding structure for the anti-loosening member 4 that is space-saving and reasonable is realized by using the O-ring 47 having a simple structure.

[0045] As shown in FIGS. 2 and 5, the inner flange 51 is an annular disk-shaped member having a larger diameter than the anti-loosening member 4. The inner flange 51 is selectively used together with the lock nut 55 when a disk-shaped tip tool 91 (e.g., a grinding wheel, a cutting wheel, a blade) having an insertion hole 910 is attached to the spindle 3. Therefore, the inner flange 51 is detachable from the spindle 3.

[0046] The inner flange 51 has an insertion hole 510 through which the spindle 3 is inserted and an engagement groove 511 that can engage with the base portion 41 of the anti-loosening member 4. The engagement groove 511 is provided at the upper portion of the inner flange 51 and extends linearly in the diameter direction of the inner flange 51. The pair of side surfaces of the engagement groove 511 are parallel to each other and are substantially parallel to the plane including the drive shaft DX when the inner flange 51 is fitted onto the spindle 3. Further, a cylindrical portion 515 that protrudes downward so as to surround the insertion hole 510 is provided on the lower side of the inner flange 51. The cylindrical portion 515 is configured to fit into the insertion hole 910 of the tip tool 91.

[0047] On the one hand, as shown in FIG. 4, the lower part of the base portion 41 of the anti-loosening member 4 is configured to fit into the engagement groove 511. More specifically, two recesses 458 facing each other in the diameter direction of the base portion 41 are provided at the lower part of the base portion 41. The two recesses 458 are in a point-symmetrical relationship about the drive shaft DX in a bottom view. Each recess 458 is formed in an L-shaped cross section and has a side surface 459 substantially parallel to the plane including the drive shaft DX so as to correspond to the side surface of the engagement groove 511. That is, the lower part of the base portion 41 has a pair of side surfaces 459 that are parallel to each other and substantially parallel to the plane including the drive shaft DX in a state where the base portion 41 is fitted into the spindle 3 so as to correspond to the side surface of the engagement groove 511. Therefore, when the lower part of the base portion 41 is fitted into the engagement groove 511 and the side surface 459 of the recess 458 faces the side surface of the engagement groove 511, the inner flange 51 receives the transmission of the rotational driving force from the anti-loosening member 4 and rotates integrally with the spindle 3 and the anti-loosening member 4. Note that the engagement structure between the inner flange 51 and the anti-loosening member 4 is not limited to this example and may be changed as appropriate.

[0048] In this embodiment, the two recesses 458 are arranged below the peripheral wall portion 45 so as to correspond to the two peripheral wall portions 45. More specifically, as shown in FIGS. 4 and 6, each recess 458 is provided at a portion directly below the rotation transmission portion 452 and the stopper portion 454 of the corresponding peripheral wall portion 45. Further, in this embodiment, the extending portion 456 of the peripheral wall portion 45 extends in the direction opposite to the rotation direction RD from the end on the side opposite to the rotation direction RD of the recess 458. That is, the peripheral wall portion 45 extends in the direction opposite to the rotation direction RD beyond the portion of the base portion 41 where the recess 458 is formed.

[0049] Thus, in this embodiment, the recess 458 is provided in the vertical direction by utilizing the portion where the heights of the rotation transmission portion 452 and the stopper portion 454 are added to the base portion 41. Thereby, while suppressing the vertical height of the anti-loosening member 4, the recess 458 necessary for engagement with the inner flange 51 can be provided. Further, by providing the extending portion 456, while suppressing the vertical height of the entire anti-loosening member 4, thinning of the portion where the recess 458 is formed can be avoided, and sufficient strength can be ensured.

[0050] As shown in FIG. 2, the lock nut 55 is a disk-shaped female screw member having a screw hole 550 in the central portion. The lock nut 55 is fixed to the spindle 3 by being screwed onto the male screw portion 31 of the spindle 3. As described above, the lock nut 55 is a member that is selectively used together with the inner flange 51 when the disk-shaped tip tool 91 is attached to the spindle 3. A cylindrical portion 555 that protrudes upward so as to surround the screw hole 550 is provided above the lock nut 55. The cylindrical portion 555 is configured to fit into the insertion hole 910 of the tip tool 91.

[0051] Hereinafter, the operation of the grinder 1 will be described.

[0052] First, the user attaches an appropriate tip tool 91 to the grinder 1 according to the desired machining operation. When the tip tool 91 is a disk-shaped tip tool 91, the user first fits the inner flange 51 around the spindle 3 from below the spindle 3 and engages the engagement groove 511 with the lower portion of the anti-loosening member 4. Then, the user places the tip tool 91 around the spindle 3 and moves it upward to fit the cylindrical portion 515 of the inner flange 51 into the upper portion of the insertion hole 910. The user further tightens the lock nut 55 onto the male screw portion 31 with the upper portion of the cylindrical portion 555 of the lock nut 55 fitted into the lower portion of the insertion hole 910 of the tip tool 91. Thereby, the tip tool 91 is clamped by the inner flange 51 and the lock nut 55 and fixed to the spindle 3.

[0053] Note that the lock nut 55 is tightened onto the male screw portion 31 in the direction opposite to the rotation direction RD. Therefore, due to friction, the inner flange 51 and the anti-loosening member 4 also rotate in the direction opposite to the rotation direction RD with respect to the spindle 3. The anti-loosening member 4 is held at a position where the rotation transmission surfaces 451 of the two peripheral wall portions 45 are respectively in contact with the side surfaces 333 of the two protruding portions 331 of the flange portion 33 (the position shown by the solid line in FIG. 7).

[0054] When the user manually operates the switch knob and moves it to the on position, the motor 21 is driven, and the spindle 3 and the tip tool 91 fixed to the spindle 3 are rotationally driven in the rotation direction RD. As described above, since the tightening direction of the lock nut 55 is opposite to the rotation direction RD, the screwing of the lock nut 55 does not loosen.

[0055] When the user manually operates the switch knob and moves it to the off position, the drive of the motor 21 is stopped, and the brake device 25 operates as described above. The output shaft 215 and the spindle 3 quickly stop rotating, but the tip tool 91 tries to continue rotating in the rotation direction RD due to inertia. Due to friction, the lock nut 55, the inner flange 51, and the anti-loosening member 4 also try to continue rotating in the rotation direction RD with respect to the spindle 3, that is, in the direction in which the screwing of the lock nut 55 loosens.

[0056] On the other hand, the anti-loosening member 4 rotates in the rotation direction RD with respect to the spindle 3 and at the same time is displaced downward while elastically deforming the O-ring 47 by the action of the first inclined surface 336 of the flange portion 33 and the second inclined surface 412 of the base portion 41 that slide relative to each other. The anti-loosening member 4 presses the lock nut 55 downward via the inner flange 51 and the tip tool 91 due to the wedge effect of the first inclined surface 336 and the second inclined surface 412. Thereby, loosening of the lock nut 55 is suppressed. Also, as described above, by setting the inclination angles of the first inclined surface 336 and the second inclined surface 412 to be larger than the lead angle of the thread of the male screw portion 31, it is possible to surely prevent the lock nut 55 from loosening.

[0057] Although detailed illustration is omitted, among the tip tools 91 for the grinder 1, there are those that can be attached to the spindle 3 without the inner flange 51 and the lock nut 55. Such a tip tool 91 is provided with a female screw portion, and is attached by screwing the female screw portion onto the male screw portion 31 of the spindle 3. The anti-loosening member 4 of the present embodiment exhibits the same effect as that exerted on the lock nut 55 even against loosening of the tip tool 91 having such a female screw portion.

[0058] As described above, the grinder 1 of the present embodiment includes an anti-loosening member 4 that prevents loosening of the lock nut 55 or the tip tool 91 having a female screw portion in response to the rotation of the spindle 3 being stopped. The anti-loosening member 4 includes a base portion 41 having a second inclined surface 412 that slidably contacts the first inclined surface 336 of the flange portion 33 of the spindle 3, and a peripheral wall portion 45 that receives a rotational driving force from the flange portion 33 when the spindle 3 is rotationally driven.

[0059] The peripheral wall portion 45 is provided not over the entire circumference of the outer edge portion of the base portion 41 but only partially, and an opening (gap) 401 exists radially outside the flange portion 33. For this reason, compared with a configuration in which the peripheral wall portion 45 is provided over the entire circumference of the outer edge portion of the base portion 41, dust is less likely to accumulate in the region 450 of the peripheral wall portion 45. Further, even if dust enters the region 450, when the anti-loosening member 4 rotates integrally with the spindle 3, the dust can be effectively discharged by centrifugal force through the opening 401. Thereby, it is possible to reduce the possibility that dust enters between the first inclined surface 336 and the second inclined surface 412, preventing the displacement of the anti-loosening member 4 and reducing the anti-loosening effect.

[0060] Also, in the present embodiment, the upper end of the peripheral wall portion 45 of the anti-loosening member 4 is approximately at the same level as or below the vertical center of the flange portion 33. Thereby, an anti-loosening member 4 having a structure in which dust is less likely to accumulate is realized.

[0061] Further, the peripheral wall portion 45 includes an extending portion 456 that extends from the rotation transmission portion 452 in the direction opposite to the rotation direction RD. Therefore, it is possible to reduce the possibility of dust entering between the rotation transmission surface 451 and the side surface 333 of the flange portion 33 from the radially outer side of the flange portion 33. In particular, in the present embodiment, since the extending portion 456 corresponds to the entire gap (the region between the first plane P1 and the second plane P2) that may occur between the side surface 333 and the rotation transmission surface 451, the entry of dust can be effectively prevented.

[0062] Furthermore, in the present embodiment, the base portion 41 has a passage 403 that extends from the radially inner end to the radially outer end of the base portion 41 below the flange portion 33. Therefore, even if dust enters below the flange portion 33 in the region 450, the dust can be effectively discharged through the passage 403. In particular, the passage 403 is provided adjacent to the end 413 of the second inclined surface 412 on the side opposite to the rotation direction RD of the spindle 3. Since the second inclined surface 412 is inclined downward as it goes in the rotation direction, the end 413 of the second inclined surface 412 is at the uppermost position in the vertical direction among the second inclined surface 412. Therefore, by providing the passage 403 adjacent to this end 413, the vertical dimension of the passage 403 can be maximized. Thereby, the dust discharge effect can be enhanced.

[0063] The correspondence between each component (feature) of the above embodiment and each component (feature) of the present disclosure or invention is shown below. However, each component of the embodiment is merely an example and does not limit each component of the present disclosure or the present invention.

[0064] The grinder 1 is an example of a "rotary tool". The spindle 3 is an example of a "spindle". The rotation direction RD is an example of a "first direction". The male screw portion 31 is an example of a "male screw portion". The flange portion 33 is an example of a "flange portion". Each of the lock nut 55 and the tip tool 91 having a female screw portion is an example of a "female screw member". The anti-loosening member 4 is an example of an "anti-loosening member". The first inclined surface 336 is an example of a "first inclined surface". The base portion 41 is an example of a "base portion". The second inclined surface 412 is an example of a "second inclined surface". The peripheral wall portion 45 is an example of a "peripheral wall portion". The passage 403 is an example of a "passage". The end 413 is an example of "the end of the second inclined surface on the side opposite to the first direction in the circumferential direction". The rotation transmission portion 452 and the rotation transmission surface 451 are examples of a "rotation transmission portion" and a "rotation transmission surface", respectively. The extending portion 46 is an example of an "extending portion". The stopper portion 454 and the stopper surface 453 are examples of a "stopper portion" and a "stopper surface", respectively. The first plane P1 and the second plane P2 are examples of a "first plane" and a "second plane", respectively. The inner flange 51 is an example of an "annular member". The concave portion 458 is an example of a "concave portion". The groove 35 is an example of an "annular groove". The O-ring 47 is an example of an "annular elastic body".

[0065] Note that the above embodiment is merely an example, and the power tool according to the present disclosure is not limited to the illustrated grinder 1. For example, the following changes can be made. Also, at least one of these changes can be adopted in combination with at least one of the features of the grinder 1 illustrated in the embodiment and those described in each claim.

[0066] For example, the rotary tool according to the present disclosure is not limited to a so-called angle grinder such as the grinder 1. Non-limiting examples of the rotary tool according to the present disclosure include a straight grinder, a sander, and a polisher. When the rotary tool includes a brake device for a motor or a spindle, the anti-loosening structure according to the present disclosure is particularly useful. The brake device is not limited to the friction type brake device 25 of the above embodiment, and may be a meshing type brake device or an electric type brake that electrically brakes the motor 21.

[0067] The flange portion, the anti-loosening member, and the female screw member of the spindle according to the present disclosure are not limited to the flange portion 33, the anti-loosening member 4, and the lock nut 55 of the above embodiment, and their configurations (for example, shape, size, engagement / connection mode with other members) may be appropriately changed. For example, the number of the protruding portion 331 (the first inclined surface 336) of the flange portion 33 and the convex portion 411 (the second inclined surface 412) of the corresponding base portion 41 may be one or three or more. Similarly, the number of the protruding portion 331 (the side surface 333) of the flange portion 33 and the corresponding peripheral wall portion 45 (the rotation transmission portion 452, the stopper portion 454, the extension portion 456) may be one or three or more.

[0068] In view of the gist of the present invention and the above embodiment, the following aspects are constructed. At least one of the following aspects can be adopted in combination with at least one of the features of the embodiment and its modification examples or the features described in each claim. [Aspect 1] The spindle further includes an annular member removably disposed around the spindle between the anti-loosening member and the male screw portion. The annular member is configured to engage with the anti-loosening member and rotate integrally with the anti-loosening member. The female screw member is a nut. The annular member and the nut are configured to sandwich a tip tool fitted around the spindle and fix it to the spindle when the nut is tightened onto the male screw portion. Note that the inner flange 51 is an example of the "annular member" in this embodiment. [Aspect 2] The female screw member is a tip tool having a female screw portion that can be screwed into the male screw portion.

Explanation of Reference Numerals

[0069] 1: Electric disk grinder (grinder), 10: Housing, 11: Motor housing, 15: Gear housing, 21: Motor, 215: Output shaft, 216: Driving bevel gear, 22: Switch, 25: Brake device, 251: Brake plate, 253: Brake member, 255: Biasing spring, 29: Power cord, 3: Spindle, 31: Male screw portion, 33: Flange portion, 331: Protrusion, 333: Side surface, 336: First inclined surface, 35: Groove, 38: Driven bevel gear, 4: Anti-loosening member, 401: Gap, 403: Passage, 41: Base portion, 410: Insertion hole, 411: Protrusion, 412: Second inclined surface, 413: End, 415: Recess, 45: Peripheral wall portion, 450: Region, 451: Rotation transmission surface, 452: Rotation transmission portion, 453: Stopper surface, 454: Stopper portion, 456: Extension portion, 457: End, 458: Recess, 459: Side surface, 47: O-ring, 51: Inner flange, 510: Insertion hole, 511: Engagement groove, 515: Cylindrical portion, 55: Lock nut, 550: Screw hole, 555: Cylindrical portion, 91: Tip tool, 910: Insertion hole, 92: Wheel cover, DX: Driving shaft, RX: Rotation shaft, RD: Rotation direction of spindle, P1: First plane, P2: Second plane

Claims

1. A rotary tool, comprising: A spindle configured to be rotationally driven in a first direction around a drive shaft that defines the vertical direction of the rotary tool, the spindle having a lower end portion configured as a male screw portion and a flange portion that protrudes radially outward of the spindle above the male screw portion; A female screw member removably screwed onto the male screw portion; An annular anti-loosening member fitted around the spindle above the male screw portion, the anti-loosening member being configured to rotate integrally with the spindle during rotation of the spindle in the first direction and, in response to the rotation stop of the spindle, displace downward while rotating in the first direction with respect to the spindle to suppress loosening of the female screw member; The lower surface of the flange portion includes a first inclined surface that extends in the circumferential direction around the drive shaft and slopes downward as it goes in the first direction; The anti-loosening member includes: A base portion disposed below the flange portion, the annular base portion having a second inclined surface that slidably abuts against the first inclined surface of the flange portion; A peripheral wall portion that protrudes upward along the outer edge portion of the base portion and is configured to receive a rotational driving force by abutting against the side surface of the flange portion during rotation of the spindle. The peripheral wall portion is provided only at a part of the outer edge portion of the base portion. The rotary tool is characterized by this.

2. The rotary tool according to claim 1, wherein: The base portion has a passage that extends from the radially inner end to the radially outer end of the base portion below the flange portion. The rotary tool is characterized by this.

3. The rotary tool according to claim 2, wherein: The passage is provided adjacent to an end on the side opposite to the first direction in the circumferential direction among the second inclined surfaces. The rotary tool is characterized by this.

4. A rotary tool according to any one of claims 1 to 3, in the vertical direction, an upper end of the peripheral wall portion of the anti-loosening member is lower than an upper end of the flange portion of the spindle, and the rotary tool is characterized by this.

5. A rotary tool according to claim 4, an upper end of the peripheral wall portion is at the same position as or lower than a center of the flange portion in the vertical direction, and the rotary tool is characterized by this.

6. A rotary tool according to any one of claims 1 to 5, the peripheral wall portion, has a rotation transmission portion having a rotation transmission surface configured to receive the rotation driving force from the spindle, and includes an extension portion extending in the second direction from an end on the second direction side, which is opposite to the first direction, of the rotation transmission portion on a radially outer side of the flange portion, and the rotary tool is characterized by this.

7. A rotary tool according to claim 6, the peripheral wall portion further includes a stopper portion having a stopper surface configured to contact the side surface of the flange portion to restrict rotation of the anti-loosening member when the anti-loosening member rotates in the first direction with respect to the spindle, the extension portion extends along the outer edge portion of the base from at least a virtual first plane including the rotation transmission surface to a virtual second plane including the stopper surface, and the rotary tool is characterized by this.

8. A rotary tool according to claim 6 or 7, further includes an annular member removably disposed around the spindle between the anti-loosening member and the male screw portion, the annular member is configured to engage with the anti-loosening member and rotate integrally with the anti-loosening member, a recess for engaging with the annular member is formed in a lower portion of the rotation transmission portion of the base portion, The extending portion is a rotary tool, characterized in that it extends in the second direction from an end on the second direction side of the concave portion among the concave portions.

9. A rotary tool according to any one of claims 1 to 8, further comprising an annular elastic body mounted in an annular groove formed on an outer peripheral surface of the spindle, wherein the anti-loosening member is held by the elastic body so as to be rotatable about the drive shaft with respect to the spindle and movable in the vertical direction as the elastic body elastically deforms.

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