ROTATIONSWERKZEUG

Abstract

The spindle has a lower end portion configured as an externally threaded portion and a flange portion protruding radially outward from the spindle above the externally threaded portion. The anti-loosening member is fitted around the spindle above the externally threaded portion. The flange portion has a lower surface including a first inclined surface extending in the circumferential direction around the drive axis and inclined downward toward the first direction. The anti-loosening member includes an annular base portion having a second inclined surface slidably contacting the first inclined surface, and a peripheral wall portion protruding upward along the outer edge portion of the base portion and abutting against the side surface of the flange portion during rotation of the spindle to receive the rotational drive force. The peripheral wall portion is provided only in a part of the outer edge portion of the base portion.

Description

TECHNICAL FIELDThe present disclosure relates to a hand-held power tool (electrically driven tool) configured to rotationally (rotationally) drive a tool accessory (e.g., a grinding wheel) removably attached to, e.g., a spindle of the power tool. The power tool, which is referred to simply as a rotary tool below, may be, for example, a grinder (e.g., an angle grinder, a straight grinder).BACKGROUNDA rotary tool (e.g., grinder) rotationally drives a tool accessory that is removably supported on a spindle. The tool accessory is fixed to the spindle by, for example, tightening a nut on the spindle. In some cases, the nut may be loosened when the rotation of the spindle is stopped suddenly. To solve this problem, JP 2012-200 794 A discloses a grinder having an anti-loosening member (anti-loosening member). The anti-release member is configured such that when the rotation of the spindle is stopped suddenly, the anti-release member moves toward the tool accessory by an action of an inclined surface (cam surface) provided on each of a flange portion of the spindle and the anti-release member.BRIEF SUMMARYIn the grinding apparatus described above, the flange portion of the spindle is fitted with play into a fitting recess provided in the anti-release member. The lower surface of the flange portion of the spindle constitutes the inclined surface abutting against the inclined surface on the bottom surface of the fitting recess. With such a configuration, the anti-release member cannot sufficiently move on the inclined surface due to the accumulation of dust in the fitting recess, thereby failing to achieve a sufficient anti-release effect.In view of the above-described circumstances, it is a non-limiting object of the present disclosure to provide an improvement in an anti-release structure in a rotary tool.The above object is achieved by a rotary tool according to claim 1.According to a non-limiting aspect of the present disclosure, there is provided a rotary tool including a spindle, an internally threaded member, and an anti-loosening member (anti-loosening member). The spindle is configured to be rotationally driven in a first direction about a drive axis defining the up-down direction of the rotary tool. The spindle has a lower end portion formed as an externally threaded portion and a flange portion projecting radially outward from the spindle above the externally threaded portion. The female threaded member is removably threaded onto the male threaded portion. The anti-release member has a ring shape and is fitted around the spindle above the male screw portion. The anti-loosening member is configured to (i) integrally rotate with the spindle when the spindle rotates in the first direction, and (ii) restrict loosening (loosening) of the female threaded member by displacing downward in response to stopping the rotation of the spindle while rotating in the first direction with respect to the spindle.The lower surface of the flange portion of the spindle has a first inclined surface. The first inclined surface extends in the circumferential direction around the drive axis and is inclined downward toward the first direction. The anti-release member has a base portion and peripheral wall portions. The base portion is annular and is located below the flange portion. The base portion has a second inclined surface slidably contacting the first inclined surface of the flange portion. The peripheral wall portions protrude upward along the outer edge portion (outer edge portion) of the base portion. Each circumferential wall portion is configured to abut against the side surface of the flange portion during rotation of the spindle for receiving the rotational driving force. The peripheral wall portions are provided only in a part of the outer edge portion of the base portion.In the rotary tool of the present aspect, when the spindle that has been rotated in the first direction stops the rotation, by action of the first inclined surface of the flange portion of the spindle and the second inclined surface of the anti-release member, the anti-release member moves downward while rotating in the first direction with respect to the spindle. This exerts a force on the female threaded member to press the female threaded member downward, thereby restraining the loosening of the female threaded member.Further, the anti-release member has the peripheral wall portion that stands upward from the base portion for receiving the transmission of the rotational driving force from the spindle. However, the peripheral wall portions are provided only partially, instead of entirely at the periphery of the outer edge portion of the base portion. That is, an opening (a gap or a space) which is a region that is not covered (claimed) by the circumferential wall portion is provided radially outward of the flange portion. Therefore, as compared with the configuration in which the peripheral wall portion is provided as a whole on the periphery of the outer edge portion of the base portion, dust is less likely to accumulate in a region (space) radially inward of the peripheral wall portion. Further, if dust enters this area, the dust can be effectively discharged (discharged) by the centrifugal force through the opening (gap) when the anti-release member rotates integrally with the spindle. This reduces the possibility that dust enters between the first inclined surface and the second inclined surface, and thus prevents the displacement of the anti-loosening member, thereby reducing its anti-loosening effect.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a cross-sectional view of a sander. FIG. 2 is a partially enlarged view of FIG. 1. FIG. 3 is an exploded perspective view of a spindle and an anti-release member. FIG. 4 is another exploded perspective view of a spindle and an anti-release member. FIG. 5 is a perspective view of a spindle, an anti-release member, and an inner flange. FIG. 6 is a plan view of an anti-release member. FIG. 7 is an explanatory view of positions of a flange portion of a spindle and an anti-release member.DETAILED DESCRIPTION OF THE EMBODIMENTSIn a non-limiting embodiment of the present disclosure, a base portion may include a passage extending from a radially inner end to a radially outer end of the base portion below the flange portion. According to this embodiment, even when dust enters a radially inner portion of the circumferential wall portion, the dust can be discharged (discharged) not only from (out of) the opening radially outside the flange portion but also from (out of) the passage below the flange portion.In addition to or instead of the above-described embodiment, the passage may be adjacent to an end of the second inclined surface, the end being opposite to the first direction in the circumferential direction. The second inclined surface is inclined downward toward the first direction corresponding to the first inclined surface. Therefore, the end of the second inclined surface opposite to the first direction is at the uppermost position of the second inclined surface in the up-down direction. Therefore, by providing a passage adjacent to the end, the dimension of the passage in the up-down direction can be maximized.In addition to or instead of the above-described embodiment, the upper end of the circumferential wall portion of the anti-release member may be at a lower position than an upper end of the flange portion of the spindle in the up-down direction. Moreover, the upper end of the anti-release member may be at a position equal to or below the center of the flange portion in the up-down direction. According to these embodiments, the anti-release member can be made more resistant to dust accumulation.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 include a rotation transmission surface configured to receive (receive) the rotational driving force from the spindle. The extending portion may extend in the second direction from an end on the side of the second direction, which is opposite to the first direction, of the rotation transmitting portion while being radially outside of the flange portion. According to this embodiment, the extending portion reduces the possibility that dust enters between the rotation transmitting surface and the side surface of the flange portion from a portion radially outside the flange portion.In addition to or in place of the above-described embodiment, the peripheral wall portion may further include a stopper portion. The stopper portion may include a stopper surface configured to abut against the side surface of the flange portion for restricting the rotation of the anti-release member when the anti-release member rotates in the first direction with respect to the spindle. The extending portion may extend along an outer edge portion of the base portion at least from a virtual first plane including the rotation transmitting surface to a virtual second plane including the stopper surface. The flange portion may rotate between a position where the side surface of the flange portion abuts against the rotation transmitting surface and a position where the side surface abuts against the abutting surface. Thus, a region (region) between the first plane and the second plane corresponds to a gap that can be generated between the side surface of the flange portion and the rotation transmission surface. According to this embodiment, since the extending area corresponds to the entire gap, dust can be more effectively restricted from entering.In addition to or in place of the above-described embodiment, the rotary tool may further include an annular member removably provided around the spindle between the anti-release member and the male threaded portion. The annular member may be configured to engage the anti-release member and rotate integrally with the anti-release member. A recess configured to be engaged with the annular member may be formed in a lower portion of the rotation transmission portion at the base portion. The extending portion may extend in the second direction across an end on a side of the second direction of the recess. According to this embodiment, since the recess utilizing the region where the height of the rotation transmission portion is added to the base portion in the up-down direction is provided, the recess necessary for engagement with the annular member can be provided while suppressing the height of the anti-release member in the up-down direction from being restricted. Further, the provision of the extending portion also ensures sufficient strength by avoiding thinning of the portion in which the recess is formed while restricting the height of the entire anti-release member in the up-down direction.In addition to or in place of the above-described embodiment, the rotary tool may further include an annular elastic body attached to an annular groove formed on the outer circumferential surface of the spindle. The anti-release member may be held by the elastic body such that the anti-release member is (i) rotatable about the drive axis with respect to the spindle and (ii) movable in the up-down direction with respect to the spindle due to the elastic deformation of the elastic body. According to this embodiment, a rational retaining structure for the anti-release member with less space can be achieved by using the elastic body with a simple structure.The following specifically describes a representative and non-limiting embodiment of the present disclosure with reference to the drawings. In the following embodiment, a hand-held electrically driven disk grinder (angle grinder) 1 (hereinafter, simply referred to as "grinder 1") will be described as an example of a rotary tool according to the present disclosure.First, a general structure of the grinder 1 will be described. As shown in FIG. 1, the grinder 1 includes a motor 21, a spindle 3 operatively connected to an output shaft 215 of the motor 21, and a housing 10 in which the motor 21 and the spindle 3 are accommodated. The housing 10 is an elongated hollow body forming an outer periphery of the sander 1. The motor 21 is arranged such that a rotational axis RX of the output shaft 215 extends generally parallel to a longitudinal axis of the housing 10. The spindle 3 is disposed within an end portion in the longitudinal direction of the housing 10. The spindle 3 is supported inside the housing 10 so as to be rotatable about a drive axis DX. The drive axis DX crosses (is specifically perpendicular to) the rotation axis RX of the output shaft 215. For this reason, the grinder is also referred to as an angle grinder.An end portion of the spindle 3 in an axial direction of the spindle 3 is exposed to the outside of the housing 10. A tool accessory 91 is removably attached to the one end portion of the spindle 3. For example, a grinding wheel, a cutting wheel, a blade (blade), and a brush or the like are available as the tool accessory 91 that can be attached to the grinder 1. The user selects an appropriate tool accessory 91 according to a desired machining operation and fixes the selected tool accessory 91 to the grinder 1. when the spindle 3 is driven to rotate about the drive axis DX by the motor 21, the tool accessory 91 is rotated to perform a machining operation with respect to a workpiece. The grinding apparatus 1 can perform a machining operation such as grinding, polishing, and cutting with respect to a workpiece depending on the type of the tool accessory 91. The tool accessory 91 is partially covered by a grinding wheel cover 92 attached to the housing 10.The detailed configuration of the grinder 1 will be described below. For convenience of description, the direction in which the drive axis DX extends is defined as an "up-down direction" of the grinder 1. In the up-down direction, the one end side of the spindle 3 to which the tool accessory 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 direction in which the rotation axis RX of the output shaft 215 extends is defined as a "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 sander 1, and the opposite side is defined as the back side of the sander 1. A direction perpendicular to both the up-down direction and the front-back direction is defined as a "left-right direction" of the sander 1. Further, each direction perpendicular to the drive axis DX is defined as the radial direction of the spindle 3. In the radial direction, a direction away from the drive axis DX is defined as a radially outward direction, and a direction approaching the drive axis DX is defined as a radially inward direction.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.The motor housing 11 is an elongated cylindrical housing extending in the front-rear direction. The motor housing 11 is configured to function as a grip portion held by the user. The motor housing 11 accommodates the motor 21 and a switch 22. The output shaft 215 of the motor 21 extends in the front-rear direction. The front and rear end portions of the output shaft 215 are supported by bearings, respectively. The switch 22 is located behind the motor 21, and the switch 22 is operatively connected to a shift knob (not shown). The shift knob is located outside the motor housing 11 and is moved between an OFF position and an ON position in response to a manual operation by the user. The switch 22 is turned on and off according to the movement of the shift knob. The motor 21 is driven while the switch 22 is ON.In the present embodiment, the sander 1 operates with electric power supplied from an external alternating current (AC) power source via an electric cable 29 extending from the rear end portion of the motor housing 11. However, the sander 1 may be configured to operate (operate) with electric power supplied from a removably mounted rechargeable battery.Further, as shown in FIG. 2, the motor housing 11 also houses a mechanical brake device 25. Specifically, the brake device 25 is located at the front of the motor 21 on the motor housing 11. The brake plate 251 is disk-shaped, 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 the rear surface thereof, and is disposed on the front side of the brake plate 251 so as to be opposed to the brake plate 251. The biasing spring 255 is disposed at the front of the brake member 253 and biases the brake member 253 rearward toward the brake plate 251.The brake member 253 is configured to move in response to the movement of the shift knob. Specifically, the brake member 253 is firmly (strongly) pressed against the brake plate 251 by the biasing force of the biasing spring 255 while the shift knob is in the OFF position. When the user moves the shift knob to the ON position, the brake member 253 moves forward against the biasing force of the biasing spring 255 to be removed from the brake plate 251, thereby enabling rotation of the output shaft 215 of the motor 21. When the user moves the shift knob to the OFF position, the driving of the motor 21 is stopped. Also, the brake member 253 is strongly pressed against the brake plate 251 by the biasing force of the biasing spring 255, whereby the output shaft 215 and the spindle 3 are braked by the brake plate 251.As shown in FIG. 2, the spindle 3 is accommodated in the gear housing 15. The spindle 3 is a long round rod-shaped shaft (cylindrical member). The spindle 3 is disposed in the gear housing 15 while extending in the up-down direction, and is supported by a plurality of bearings so as to be rotatable about the drive axis DX. A driven bevel gear 38 is fixed to an upper part of the spindle 3. The front end portion of the output shaft 215 of the motor 21 projects into the transmission case 15, and a driving bevel gear 216 meshing with the driven bevel gear 38 is fixed thereto.With this configuration, the rotation of the output shaft 215 is transmitted to the spindle 3 when the motor 21 is driven, thereby rotationally driving the spindle 3. Since the grinder 1 is a rotary tool that rotationally drives the tool accessory 91 in only one direction, the spindle 3 is rotationally driven in only a predetermined direction about the drive axis DX. Specifically, the rotational direction RD of the spindle 3 (see FIG. 3 ) is clockwise when viewed from above.The lower end portion of the spindle 3 protrudes downward through an opening provided at the lower end of the gear case 15 and is exposed to the outside of the case 10. The lower end portion of the spindle 3 is configured as an externally threaded portion 31. The male screw portion 31 is a portion having an outer peripheral surface on which a thread is formed, and occupies a predetermined range from the lower end of the spindle 3. A lock nut 55 is removably screwed onto the male threaded portion 31 for fixing the tool accessory 91 to the spindle 3.As shown in FIGS. 2 to 4, the spindle 3 has a flange portion 33 projecting radially outward. The flange portion 33 is spaced apart from the male threaded portion 31 and is provided above the male threaded portion 31. The flange portion 33 of the present embodiment has a pair of (two) protruding portions 331 protruding radially outward from the round rod-shaped portion of the spindle 3. The two protruding portions 331 project in directions opposite to each other along a straight line crossing the drive axis DX. In the present embodiment, the flange portion 33 is formed integrally with the spindle 3, but the flange portion 33 may be formed as a discrete component from the spindle 3 and fixed to the spindle 3.Each of the two protruding portions 331 of the flange portion 33 has side surfaces 333 substantially parallel to each other and an arc-shaped end surface. Each side surface 333 is substantially parallel to a plane including the drive axis DX. Further, each protruding portion 331 has a lower surface having a first inclined surface 336. The first inclined surface 336 extends in a circular arc along the circumferential direction around the drive axis DX. The first inclined surface 336 is inclined at a predetermined angle with respect to a plane perpendicular to the drive axis DX. Specifically, the first inclined surface 336 is inclined downward toward the rotational direction RD of the spindle 3. The angle between the plane perpendicular to the drive axis DX and the first inclined surface 336 (hereinafter, simply referred to as the inclination angle of the first inclined surface 336) is larger than a lead angle of the thread of the male threaded portion 31.As shown in FIGS. 2 and 5, an anti-loosening member (anti-loosening member) 4 and an inner flange 51 are disposed between the male threaded portion 31 and the flange portion 33. The anti-release member may also be referred to as a locking member or a locking member.The anti-release member 4 is an annular (short cylindrical) member as a whole. The anti-release member 4 is disposed around the spindle 3 between the flange portion 33 and the male screw portion 31 (inner flange 51) in the up-down direction. The anti-release member 4 is configured to integrally rotate with the spindle 3 during the rotational drive of the spindle 3 by the rotational drive force transmitted from the flange portion 33. The anti-loosening member 4 is further configured to cooperate with the flange portion 33 so as to restrict or prevent the lock nut 55 from loosening (loosening) when the rotation of the spindle 3 is stopped.Specifically, as shown in FIGS. 3 to 7, the anti-release member 4 has a generally disk-shaped base portion 41 having an insertion hole 410 and two peripheral wall portions 45 projecting upward from the outer edge portion of the base portion 41.The two peripheral wall portions 45 are diametrically opposed to each other at the base portion 41. With this configuration, two openings (spaces, gaps) 401 are provided between the two circumferential wall portions 45 in the circumferential direction of the anti-release member 4. 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 circumferential wall portions 45 are point-symmetric in plan view with respect to the drive axis DX as the center. In a region (space) 450 between the two circumferential wall portions 45 diametrically opposed to each other, the flange portion 33 of the spindle 3 is disposed with play in the circumferential direction (see FIG. 7 ). That is, the flange portion 33 can rotate only at a predetermined angle about the drive axis DX within the portion 450. The region 450 may also be referred to as a region radially inside the circumferential wall regions 45.Each of the peripheral wall portions 45 includes a rotation transmission portion 452, a stopper portion 454, and an extending portion 456.The rotation transmission portion 452 has a rotation transmission surface 451. The rotation transmission surface 451 is a portion on an inner side surface of each circumferential wall portion 45 and is configured to abut against the side surface 333 of the flange portion 33 (protruding portion 331) when the spindle 3 is rotationally driven in the rotational direction RD and receive the transmission of the rotational power from the spindle 3 (see solid line in FIG. 7 ). The rotation transmission surface 451 is a flat surface.The stopper portion 454 has a stopper surface 453. The stopper surface 453 is another portion of the inner side surface of each circumferential wall portion 45 and is configured to abut against the side surface 333 of the flange portion 33 (protruding portion 331) when the anti-release member 4 rotates in the rotation direction RD relative to the spindle 3, thereby restricting the rotation of the anti-release member 4 (see two-dot chain line in FIG. 7 ). The stopper surface 453 is a flat surface. In the present embodiment, the stopper portion 454 (the stopper surface 453) is directly connected to an end of the rotation transmitting portion 452 (the rotation transmitting surface 451) on the rotation direction RD side. However, in another embodiment, another region that does not abut against the side surface 333 of the flange portion 33 (a region that does not contribute to the rotation transmission or rotation restriction) may be present between the stopper portion 454 (the stopper surface 453) and the rotation transmission portion 452 (the rotation transmission surface 451).The extending portion 456 is a portion connected to the other end of the rotation transmitting portion 452 on the side opposite to the rotational direction RD. The extending portion 456 extends along the outer edge of the base portion 41 radially outside the flange portion 33. the extending portion 456 extends from a virtual first plane P 1 including the rotation transmitting surface 451 to slightly beyond a virtual second plane P 2 including the stopper surface 453. As described above, the flange portion 33 can rotate between the position where the side surface 333 abuts against the rotation transmitting surface 451 (the position shown by the solid line in FIG. 7 ) and the position where the side surface 333 abuts against the stopper surface 453 (the position shown by the two-dot chain line in FIG. 7 ). Therefore, a region between the first plane P 1 and the second plane P 2 corresponds to a gap that can be formed between the side surface 333 and the rotation transmission surface 451. The extending portion 456 may be considered as a wall portion that is disposed radially outside the gap and that extends over more than the length of the gap in the circumferential direction corresponding to the gap.Each circumferential wall portion 45 is configured such that the upper end of the circumferential wall portion 45 is located at a lower position than the upper end of the flange portion 33 of the spindle 3 in the up-down direction. Specifically, the upper end of the circumferential wall portion 45 is located generally at the center of the flange portion 33 or at a position lower than the center in the up-down direction. Therefore, a generally upper half of the flange portion 33 protrudes beyond the circumferential wall portion 45 (see FIG. 5 ).The base portion 41 has two wedge-shaped projections 411. The two protrusions 411 are positioned to respectively oppose the lower surfaces of the two protruding portions 331 of the flange portion 33 disposed in the portion 450. Each of the two protrusions 411 extends in a circular arc in the circumferential direction of the base portion 41. each of the two protrusions 411 has an upper surface formed as a second inclined surface 412 inclined downward toward the rotational direction RD of the spindle 3 at substantially the same angle as the first inclined surface 336. Therefore, the second inclined surface 412 slidably contacts the first inclined surface 336 of the corresponding protruding portion 331 when the flange portion 33 is disposed in the portion 450.An end 413 of the second inclined surface 412 (the protrusion 411) on the opposite side of the rotational direction RD (i.e., an end at which the height of the protrusion 411 in the up-down direction is maximum) and an end 457 of the adjacent circumferential wall portion 45 on the rotational direction RD side are spaced apart from each other in the circumferential direction. In other words, here, a gap is located between the end 413 of the second inclined surface 412 (the protrusion 411) and the end 457 of the circumferential wall portion 45.As shown in FIG. 2, the anti-release 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, for example, rubber (rubber). Specifically, the O-ring 47 is mounted to and held by 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 in a lower portion of the base portion 41. The O-ring 47 is fitted into the recess 415 with a slight clearance in the radial direction.With such a supporting structure, the anti-release member 4 is rotatable about the drive axis DX with respect to the spindle 3. The anti-release member 4 is also movable in the up-down direction with respect to the spindle 3 in response to the elastic deformation of the O-ring 47. Thus, in the present embodiment, a space-saving and rational support structure for the anti-release member 4 is achieved using the O-ring 47 having a simple structure.As shown in FIGS. 2 and 5, the inner flange 51 is an annular disk-shaped member having a diameter larger than the anti-release member 4. the inner flange 51 is selectively used with the lock nut 55 when a disk-shaped tool accessory 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 removable from the spindle 3.The inner flange 51 has an insertion hole 510 through which the spindle 3 is inserted and an engagement groove 511 engageable with the base portion 41 of the anti-release member 4. The engagement groove 511 is provided at an upper part of the inner flange 51 and extends linearly along the diameter of the inner flange 51. the pair of side surfaces of the engagement groove 511 are parallel to each other, and in a state in which the inner flange 51 is fitted around the spindle 3, the side surfaces are substantially parallel to a plane including the drive axis DX. Further, on the lower side of the inner flange 51, a cylindrical portion 515 projects downward to surround the insertion hole 510. The cylindrical portion 515 is configured to fit into the insertion hole 910 of the tool accessory 91.As shown in FIG. 4, the lower part of the base portion 41 of the anti-release member 4 is configured to fit in the engagement groove 511. Specifically, two diametrically opposed recesses 458 are provided at the lower part of the base portion 41. The two recesses 458 are point-symmetric in the center in the bottom view with respect to the drive axis DX. Each recess 458 has an L-shaped cross section and has a side surface 459 substantially parallel to the plane containing the drive axis DX corresponding to the side surface of the engaging groove 511. In other words, the lower part of the base portion 41 has a pair of side surfaces 459, which are parallel to each other and also parallel to the plane containing the drive axis DX, with the base portion 41 fitted around the spindle 3, corresponding to the side surfaces of the engagement groove 511. Accordingly, the inner flange 51 receives the rotational driving force transmitted from the anti-release member 4, and rotates integrally with the spindle 3 and the anti-release member 4 in a state in which the lower part of the base portion 41 is fitted into the engagement groove 511 and the side surfaces 459 of the recess 458 and the side surfaces of the engagement groove 511 are opposed to each other. The engagement structure of the inner flange 51 and the anti-release member 4 is not limited to this example and may be modified as necessary.In the present embodiment, the two recesses 458 are disposed below the peripheral wall portions 45 corresponding to the two peripheral wall portions 45. Specifically, as shown in FIGS. 4 and 6, each recess 458 is located in a portion of the corresponding circumferential wall portion 45 directly below the rotation transmission portion 452 and the stopper portion 454. Further, in the present embodiment, the extension portion 456 of the circumferential wall portion 45 extends more than the end of the recess 458 in the opposite direction of the rotational direction RD in a direction opposite to the rotational direction RD. In other words, the peripheral wall portion 45 extends beyond a portion of the base portion 41 where the recess 458 is formed in the opposite direction to the rotational direction RD.As described above, in the present embodiment, the recess 458 is provided using the region where the heights of the rotation transmission portion 452 and the stopper portion 454 are added to the base portion 41 in the up-down direction. This enables the provision of the recess 458 necessary for engagement with the inner flange 51 while restricting the height of the anti-release member 4 in the up-down direction. Further, the provision of the extending portion 456 also ensures sufficient strength by avoiding thinning of the portion where the recess 458 is formed while restricting the height of the entire anti-release member 4 in the up-down direction.As shown in FIG. 2, the lock nut 55 is a disk-shaped female threaded member having a threaded hole 550 at the center. The lock nut 55 is screwed onto the male threaded portion 31 of the spindle 3, and is therefore fixed to the spindle 3. As described above, the lock nut 55 is a member that is selectively used with the inner flange 51 when the disk-shaped tool accessory 91 is attached to the spindle 3. The upper side of the lock nut 55 has a cylindrical portion 555 protruding upward to surround the threaded hole 550. The cylindrical portion 555 is configured to fit into the insertion hole 910 of the tool accessory 91.The operation of the grinder 1 will be described below.The user first attaches a suitable tool accessory 91 to the grinder 1 according to the desired machining work. When the tool accessory 91 is a disk-shaped tool accessory 91, the user first fits the inner flange 51 around the spindle 3 from below the spindle 3 so that the engagement groove 511 engages with the lower part of the anti-release member 4. The user then places the tool accessory 91 around the spindle 3 and moves it upward to fit the cylindrical portion 515 of the inner flange 51 into an upper part of the insertion hole 910. The user further pulls the lock nut 55 on the male threaded portion 31 while fitting the upper part of the cylindrical portion 555 of the lock nut 55 into the lower part of the insertion hole 910 of the tool accessory 91. This allows the tool accessory 91 to be clamped by the inner flange 51 and the lock nut 55, and thereby fixed to the spindle 3.The lock nut 55 is rotated in the opposite direction in the rotational direction RD to be tightened on the male threaded portion 31. Therefore, due to the friction, the inner flange 51 and the anti-release member 4 also rotate in the opposite direction of the rotational direction RD with respect to the spindle 3.When the user manually operates the shift knob and operates it to the ON position, the motor 21 is driven, and the spindle 3 and the tool accessory 91 fixed to the spindle 3 are rotationally driven in the rotational direction RD. As described above, since the tightening direction of the lock nut 55 is opposite to the rotational direction RD, the lock nut 55 will not disengage (loosen) from the screwed state while the spindle 3 is rotationally driven.When the user manually operates the shift knob and moves it to the OFF position, the driving of the motor 21 is stopped, and the brake device 25 is activated as described above. Although the output shaft 215 and the spindle 3 quickly stop their rotation, the tool accessory 91 will continuously rotate in the rotational direction RD due to the inertia. Like the tool accessory 91, the lock nut 55, the inner flange 51, and the anti-release member 4 would rotate further in the rotational direction RD, i.e., in the direction in which the lock nut 55 disengages from the screwed state, with respect to the spindle 3 due to the friction.At the same time, when the anti-release member 4 rotates in the rotational direction RD with respect to the spindle 3, the anti-release member 4 moves downward 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 sliding on each other, while elastically deforming the O-ring 47. The anti-release member 4 presses the lock nut 55 downward via the inner flange 51 and the tool accessory 91 due to the wedge effect of the first inclined surface 336 and the second inclined surface 412. This restricts the lock nut 55 from loosening (loosening). Further, as described above, the inclination angles of the first inclined surface 336 and the second inclined surface 412 are set to be larger than the lead angle of the thread of the male threaded portion 31.Although detailed illustrations are omitted, some of the tool accessories 91 for use in the grinder 1 may be attached to the spindle 3 without using the inner flange 51 and the lock nut 55. Such a tool accessory 91 has an internal thread portion and is mounted by screwing the internal thread portion to the external thread portion 31 of the spindle 3. The anti-loosening member 4 of the present embodiment has the same effect on loosening such a tool accessory 91 having an internal thread portion as its effect on the lock nut 55.As described above, the grinder 1 of the present embodiment includes the anti-release member 4 that restricts release of the lock nut 55 or the tool accessory 91 having an internal thread portion when the spindle 3 stops rotating. The anti-release member 4 includes the base portion 41 having the second inclined surface 412 slidably contacting the first inclined surface 336 of the flange portion 33 of the spindle 3, and the circumferential wall portions 45 receiving the rotational driving force from the flange portion 33 when the spindle 3 is rotationally driven.The peripheral wall portions 45 are provided only partially, instead of entirely, on the periphery of the outer edge portion of the base portion 41, and here, openings (gaps) 401 are provided at a portion radially outward from the flange portion 33. Therefore, as compared with the configuration in which the peripheral wall portions 45 are provided as a whole on the periphery of the outer edge portion of the base portion 41, dust is less likely to accumulate in the portion 450 of the peripheral wall portions 45. Further, even when dust enters the region 450, the dust can be effectively discharged (discharged) by a centrifugal force through the openings 401 when the anti-release member 4 rotates integrally with the spindle 3. This reduces the likelihood that dust will enter between the first inclined surface 336 and the second inclined surface 412, and thus hinders the displacement of the anti-release member 4, thereby reducing its effect of restraining loosening.Further, in the present embodiment, the upper end of each circumferential wall portion 45 of the anti-release member 4 is positioned at approximately the center in the up-down direction of the flange portion 33 or below the center. This allows the anti-release member 4 to have a structure more resistant to dust accumulation.Further, each circumferential wall portion 45 also has an extending portion 456 extending from the rotation transmitting portion 452 in the opposite direction of the rotational direction RD. Therefore, it is possible to reduce the possibility of entry of dust between the rotation transmission surface 451 and the side surface 333 of the flange portion 33 from the radially outward direction of the flange portion 33. Specifically, in the present embodiment, the extending portion 456 corresponds to the entire part of the gap (the portion between the first plane P 1 and the second plane P 2) that may be formed between the side surface 333 and the rotation transmission surface 451, thereby effectively restricting entry of dust.Moreover, in the present embodiment, the base portion 41 has a passage 403 extending from the radially inner side end to the radially outer side end of the base portion 41 below the flange portion 33. Therefore, even if dust enters the region 450 below the flange portion 33, the dust can be effectively discharged through the passage 403. Specifically, the passage 403 is provided adjacent to the end 413 of the second inclined surface 412, the end being on the opposite side of the rotational direction RD of the spindle 3. Since the second inclined surface 412 is inclined downward toward the rotational direction, the end 413 of the second inclined surface 412 is located at the uppermost position of the second inclined surface 412 in the up-down direction. Therefore, by providing the passage 403 adjacent to the end 413, the dimension (size) of the passage 403 in the up-down direction can be maximized. This improves the dust dissipation effect.Correspondences between each component (feature) of the above-described embodiment and each component (feature) of the present disclosure or the present invention are as follows. However, the components of the above-described embodiment are merely exemplary and do not limit the components of the present disclosure or the present invention.The grinder 1 is an example of a "rotary tool". The spindle 3 is an example of a "spindle". The rotational direction RD is an example of a "first direction". The male threaded portion 31 is an example of a "male threaded portion". The flange portion 33 is an example of a "flange portion". Each of the lock nut 55 and the tool accessory 91 having a female screw portion is an example of a "female screw member". The anti-release member 4 is an example of an "anti-release member". The first inclined surface 336 is an example of a "first inclined surface". The base region 41 is an example of a "base region". 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 "an end of the second inclined surface 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 extension portion 456 is an example of an "extension portion". The stopper portion 454 and the stopper surface 453 are examples of a "stopper portion" and a "stopper surface", respectively. The first plane P 1 and the second plane P 2 are examples of a "first plane" and a "second plane", respectively. The inner flange 51 is an example of an "annular member". The recess 458 is an example of a "recess.". The groove 35 is an example of an "annular groove". The O-ring 47 is an example of an "annular elastic body".The above-described embodiment is merely an example, and the power tool is not limited to the exemplary grinder 1. For example, the following exemplary modifications are possible. Further, at least one of these modifications may be applied in combination with at least one of the grinder 1 described in the embodiment and the claimed features.For example, the rotary tool according to the present disclosure is not limited to so-called angle grinders (angle grinders) such as the grinder 1. Non-limiting examples of rotary tools according to the present disclosure include straight grinders, grinding machines, and polishing apparatuses. When the rotary tool has a brake device for the motor or the spindle, an anti-loosening structure (anti-loosening structure) according to the present disclosure is particularly helpful. The brake device is not limited to the friction brake device 25 of the above-described embodiment, and may be a mechanically engaging brake device or an electric brake that electrically brakes the motor 21.The flange portion of the spindle, the anti-release member, and the female threaded member according to the present disclosure are not limited to the flange portion 33, the anti-release member 4, and the lock nut 55 of the above-described embodiment and the configuration thereof (e.g., shape, size, manner of engagement / connection with other members) and may be changed as appropriate. For example, the number of the protruding portions 331 (the first inclined surfaces 336) of the flange portion 33 and the corresponding protrusions 411 (the second inclined surfaces 412) of the base portion 41 may be one, three, or more. Similarly, the number of the protruding portions 331 (the side surfaces 333) of the flange portion 33 and corresponding circumferential wall portions 45 (the rotation transmitting portions 452, the stopper portions 454, and the extending portions 456) may be one, three, or more.In view of the present teachings and the above-described embodiment, the following aspects may be provided. At least one of the present aspects may be applied in combination with at least one of the features of the above-described embodiments and modification examples, and the claimed features.[Aspect 1]The rotary tool further includes an annular member configured to be removably disposed about the spindle between the anti-release member and the male threaded portion, wherein the annular member is configured to engage with the anti-release member and integrally rotate with the anti-release member, the female threaded member is a nut, and the annular member and the nut are configured to clamp the tool accessory fitted about the spindle to fix the tool accessory to the spindle when the nut is tightened to the male threaded portion.The inner flange 51 is an example of an "annular member" of the present aspect.[Aspect 2]The internally threaded member is a tool accessory that includes an internally threaded portion configured to be screwed onto the externally threaded portion.It is expressly emphasized that all features disclosed in the description and / or the claims are to be regarded as separate and independent from each other for the purpose of original disclosure as well as for the purpose of restricting the claimed invention independently of the combinations of features in the embodiments and / or the claims. It is expressly stated that all range specifications or specifications of groups of units disclose every possible intermediate value or subgroup of units for the purpose of original disclosure as well as for the purpose of restricting the claimed invention, in particular also as a boundary of a range specification.List of reference characters1: An electrically driven 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 cable, 3: spindle, 31: male threaded portion, 33: flange portion, 331: protruding portion, 333: side surface, 336: first inclined surface, 35: groove, 38: driven bevel gear, 4: anti-release 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: portion, 451: rotation transmitting 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: locking groove, 550: threaded hole, 555: cylindrical portion, 91: tool accessory, 910: insertion hole, 92: grinding wheel cover, DX: drive axis, RX: rotation axis, RD: rotation direction, P 1: first plane, P 2: second planeReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedJP 2012-200 794 A

[0002]

Claims

A rotary tool, comprising a spindle configured to be rotationally rotated in a first direction about a drive axis defining an up-down direction of the rotary tool, wherein the spindle has a lower end portion configured as an externally threaded portion and a flange portion protruding in a direction radially outward of the spindle above the externally threaded portion, an internally threaded member removably screwed onto the externally threaded portion, and an anti-loosening member having a ring shape and fitted around the spindle above the externally threaded portion, wherein the anti-loosening member is configured to (i) rotate integrally with the spindle when the spindle rotates in the first direction, and (ii) restrict loosening of the internally threaded member by displacing downward in response to stopping rotation of the spindle, while rotating in the first direction with respect to the spindle, wherein the flange portion has a lower surface having a first inclined surface extending in a circumferential direction around the drive axis and inclined downward toward the first direction, the anti-release member includes (i) an annular base portion disposed below the flange portion and having a second inclined surface slidably contacting the first inclined surface of the flange portion, and (ii) a circumferential wall portion protruding upward along an outer edge portion of the base portion and configured to abut against a side surface of the flange portion and receive the rotational driving force when the spindle rotates, and the circumferential wall portion is provided in only a part of the outer edge portion of the base portion.The rotary tool of claim 1, wherein the base portion includes a passage extending from a radially inner end to a radially outer end of the base portion below the flange portion.The rotary tool according to claim 2, wherein the passage is adjacent to an end of the second inclined surface, the end being opposite to the first direction in the circumferential direction.The rotary tool according to any one of claims 1 to 3, wherein an upper end of the circumferential wall portion of the anti-release member is at a lower position than an upper end of the flange portion of the spindle in the up-down direction.The rotary tool according to claim 4, wherein the upper end of the circumferential wall portion is located at a position that is the same as or below a center in the up-down direction of the flange portion.The rotary tool according to any one of claims 1 to 5, wherein the peripheral wall portion includes a rotation transmission portion having a rotation transmission surface configured to receive the rotational driving force from the spindle, and an extending portion that (i) is disposed radially outward of the flange portion, and (ii) extends in a second direction opposite to the first direction from an end on the second direction side of the rotation transmission portion.The rotary tool according to claim 6, wherein the peripheral wall portion further includes a stopper portion having a terminal surface configured to abut against the side surface of the flange portion for restricting rotation of the anti-release member when the anti-release member rotates in the first direction with respect to the spindle, and the extending portion extends along the outer edge portion of the base portion from at least one virtual first plane including the rotation transmitting surface to a virtual second plane including the stopper surface.The rotary tool according to claim 6 or 7, further comprising an annular member removably disposed around the spindle between the anti-release member and the male threaded portion, wherein the annular member is configured to be engaged with the anti-release member and integrally rotate with the anti-release member, a recess configured to be engaged with the annular member is formed in a lower portion of the rotation transmitting portion of the base portion, and the extending portion extends over an end on the second direction side of the recess in the second direction.The rotary tool according to any one of claims 1 to 8, further comprising an annular elastic body attached to an annular groove formed on an outer circumferential surface of the spindle, wherein the anti-release member is held by the elastic body such that the anti-release member (i) is rotatable about the drive axis with respect to the spindle and (ii) is movable in the up-down direction with respect to the spindle due to elastic deformation of the elastic body.The rotary tool according to any one of claims 1 to 9, wherein an angle between a plane perpendicular to the drive axis and the first inclined surface is larger than a lead angle of a thread of the male threaded portion.

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