JP4854063B2 - Work tools - Google Patents

Description

  The present invention relates to a work tool such as a disk grinder that performs a machining operation using the rotational motion of a tip tool.

Japanese Patent Application Laid-Open No. 11-72122 (Patent Document 1) discloses a hand-held electric screw tightening tool provided with a spindle lock mechanism for facilitating tool replacement. In this screw tightening tool, a drive shaft as a drive side rotation member and a spindle as a driven side rotation member are connected via a shaft coupling. In the shaft coupling, when a rotational force is input from the drive shaft side, the claw portion of the drive side shaft joint abuts on the claw portion of the driven side shaft joint in the circumferential direction, and thereby the rotational force of the drive shaft is applied to the spindle. However, when a rotational force (external force) is input from the spindle side, the lock member is engaged between the driven side shaft joint and the lock ring fixed to the housing, thereby fixing the rotation of the driven shaft. This is a configuration. According to the electric screw tightening tool including the spindle lock mechanism having such a configuration, it is not necessary to bother to lock the rotation of the spindle when changing the tool, and the tool can be changed easily.
In the case of the spindle lock mechanism of the above type, there is a gap between the position where the claw portion of the drive side shaft joint and the claw portion of the driven side shaft joint abut each other and the position where the lock member is engaged between the driven side shaft joint and the lock ring. A predetermined play is required in the circumferential direction. For this reason, during the rotational driving of the spindle, the rotation of the spindle becomes faster or slower than the rotation of the drive shaft due to a change (increase / decrease) in the rotational load on the driven side. That is, relative rotation occurs between the spindle and the drive shaft with the above play, and as a result, a separation operation and a contact operation are performed between the claw portion of the drive side shaft joint and the claw portion of the driven side shaft joint. Repeatedly, vibration or abnormal noise is generated. In view of this, in Patent Document 1, the braking force (holding) is performed so that the relative rotation of both shaft joints is suppressed between the drive side shaft joint and the driven side shaft joint, that is, the synchronous rotation of both shaft joints is maintained. (Braking force) is provided.

However, in the case of Patent Document 1, the driving-side shaft coupling and the driven-side shaft coupling are arranged so as to face each other in the axial direction, and the claw portions of both shaft couplings abut on each other in the circumferential direction at the opposed end portions. Is transmitted. For this reason, the arrangement position of the braking portion to which the braking force is applied in order to maintain the synchronous rotation of the driving side shaft coupling and the driven side shaft coupling is restricted to the same region as the contact region of the claw portion. That is, the configuration of Patent Document 1 has a low degree of freedom regarding the arrangement position of the braking portion, and there is still room for improvement in this respect.
JP 11-72122 A

  The present invention has been made in view of the above points, and in a working tool having a rotary tip tool, synchronous rotation is performed by adding a holding force to maintain the synchronous rotation of the driving side rotating member and the driven side rotating member. An object of the present invention is to provide a technique effective in increasing the degree of freedom with respect to the arrangement position of the holding portion.

In order to achieve the above object, the invention described in each claim is configured.
According to the first aspect of the present invention, the drive-side rotating member disposed on the work tool main body and rotated by the drive source, and the drive-side rotating member disposed in the work tool main body and passing through the rotation axis of the drive-side rotating member. The driven-side rotating member is coaxially fitted to the driving-side rotating member, is rotated together with the driven-side rotating member, a power receiving portion provided in a protruding shape in the radial direction on the driven-side rotating member, and the driving-side rotating member. A power transmission unit that contacts the power receiving unit and transmits the rotational force of the driving side rotating member to the driven side rotating member, and a tip that performs a predetermined machining operation by being driven to rotate through the driven side rotating member A work tool having a tool. The “drive source” in the present invention typically corresponds to an electric motor, but is not limited to the electric motor, and widely includes an air motor or an engine. The “work tool” in the present invention typically corresponds to a disk grinder that performs a grinding work or a polishing work on a workpiece by rotating a grindstone as a tip tool, but is not limited to a disk grinder. The present invention can be widely applied to any work tool that performs a predetermined machining operation on a workpiece with a tip tool that performs a rotating operation.

  The work tool of the present invention is provided in the work tool main body, and when the driven side rotating member rotates in synchronization with the driving side rotating member through the contact state between the power transmission unit and the power receiving unit, the driven side rotation member A locking member that permits rotation of the member and fixes the rotation of the driven side rotating member when the driven side rotating member rotates relative to the driving side rotating member. That is, when an external force is applied to the driven-side rotating member in a direction in which the driven-side rotating member is rotated, when the driven-side rotating member rotates relative to the driving-side rotating member, the lock member The rotation of the driven side rotation member is fixed. For this reason, for example, when exchanging the tip tool, if an external force in the direction of relative rotation with respect to the drive side rotation member is applied to the driven side rotation member, the rotation of the driven side rotation member is fixed by the lock member. This makes it possible to easily attach and remove the tip tool. Here, “synchronous rotation” refers to a state in which the driving-side rotating member and the driven-side rotating member rotate together without any circumferential displacement.

  The work tool according to the present invention is configured such that the driving side rotating member and the driven side rotating member maintain the synchronous rotation through the contact state between the power transmission unit and the power receiving unit. When holding force is applied to the member to suppress relative rotation and an external force in the circumferential direction exceeding the holding force is applied to the driven side rotating member, relative rotation of the driven side rotating member with respect to the driving side rotating member is allowed. A synchronous rotation holding unit is provided. According to the present invention, in a state where the tip tool is driven to perform a predetermined machining operation, the rotation of the driven side rotating member is rotated by the change (increase / decrease) in the rotational load of the driven side rotating member. Even if an attempt is made to advance faster, that movement is restrained by the holding force of the synchronous rotation holding portion. As a result, the contact state between the power transmission unit and the power receiving unit is maintained, and the synchronous rotation of the driving side rotating member and the driven side rotating member is maintained. Thereby, generation | occurrence | production of the vibration or abnormal noise by repeating separation | spacing operation | movement and contact operation | movement between a power transmission part and a power receiving part is prevented.

  By the way, in the case of a conventional device configured to transmit the rotational force between the shaft end portions where the driving side rotation member and the driven side rotation member face each other, the arrangement position of the synchronous rotation holding portion is limited between the shaft end portions. Become. However, according to the present invention, since the driven-side rotating member is configured to pass through the driving-side rotating member, when the synchronous rotating holding portion is provided between the driving-side rotating member and the driven-side rotating member, the synchronous rotation holding is performed. The arrangement position of the portion can be set to an arbitrary position in the axial direction of the driving side rotating member and the driven side rotating member. That is, according to the present invention, a degree of freedom can be obtained with respect to the arrangement position of the synchronous rotation holding portion. Further, since the driven-side rotating member passes through the driving-side rotating member, the shafts can be aligned with each other by fitting the both rotating members. As a result, when assembling to the housing, no centering is required, and the assemblability is improved. Furthermore, by adopting a configuration in which the driven-side rotating member penetrates the driving-side rotating member, it is possible to provide a so-called both-end supported structure in which the driven-side rotating member is supported by bearings on both sides in the axial direction. And if it is the support structure by both ends, the rotational force transmission between a drive side rotation member and a driven side rotation member can be performed in the stable state between bearings.

Further, according to the present invention, the power transmission portion and the power receiving portion are arranged on one end side in the axial direction of the driving side rotating member, and the holding portion is arranged on the other end side in the axial direction of the driving side rotating member. Is done. According to this configuration, the arrangement area of the mechanism that transmits the rotational force of the driving side rotating member to the driven side rotating member, and the arrangement area of the synchronous rotation holding portion that suppresses relative rotation between the driving side rotating member and the driven side rotating member. Can be set using different end portions in the axial direction of the drive-side rotating member, so that each can be assembled using a wide space, which is effective in improving the assemblability.

(Invention of Claim 2 )
According to the invention described in claim 2, synchronization rotation holding portion has a first and a second member disposed opposite with each other in the axial direction of the driven side rotational member, which first and second These members are connected to each other via a resistance portion that exerts a resistance force against the relative movement in the circumferential direction, so that a holding force that suppresses relative rotation is applied to the driving side rotating member and the driven side rotating member. The configuration is as follows. In the present invention, “connected to each other via a resistance portion in which a resistance force acts on relative movement in the circumferential direction” means that the first member and the second member arranged in an opposing manner are a convex portion. A mode in which a resisting force is applied by engagement with the recess, and a resisting force is applied by frictional contact in a state where the first member and the second member arranged in an opposing manner are elastically biased to each other. A mode in which the first member and the second member arranged opposite to each other are connected via an elastic body such as rubber or a spring, and a resistance force is applied by elastic deformation of the elastic body, etc. .

(Invention of Claim 3 )
According to the third aspect of the present invention, the first member is configured as a sphere provided on the driving-side rotating member, and the second member is configured as a plate-like member provided on the driven-side rotating member. The holding force for suppressing the relative rotation between the driving side rotating member and the driven side rotating member is applied through the engagement between the spherical body and the spherical body holding portion provided on the plate-like member. According to the present invention, a synchronous rotation holding unit having a simple structure can be provided.

  According to the present invention, in a work tool provided with a rotary tip tool, the arrangement position of the synchronous rotation holding portion for adding a holding force to maintain the synchronous rotation of the driving side rotation member and the driven side rotation member is free. Technology that is effective in increasing the degree was provided.

(First embodiment)
Hereinafter, the first embodiment of the present invention will be described in detail with reference to FIGS. In the present embodiment, as an example of a work tool, a description will be given using a hand-held electric disc grinder used for grinding work or grinding work of various work materials such as metal, concrete, and stone. FIG. 1 is a longitudinal sectional view showing the entire configuration of the electric disc grinder 101. For convenience, a part of the rear side (the right side in the figure) is omitted in FIG. FIG. 2 is a longitudinal sectional view showing the power transmission mechanism. FIG. 3 is a diagram showing a cross-sectional structure of the power transmission mechanism, and the cross-sectional structures based on the cross-section indicating lines (AA line and BB line) in FIG. The operation modes of the respective cross-sectional structure portions are sequentially shown, wherein (I) indicates a processing operation, (II) indicates the removal of the grindstone, and (III) indicates the mounting of the grindstone. FIGS. 4 to 13 are component diagrams showing components of the power transmission mechanism, FIGS. 4 to 6 show gears, FIGS. 7 and 8 show spindles, and FIGS. 9 and 10 show lock cams. 11 and 12 show a lock ring, and FIG. 13 shows a leaf spring.

  As shown in FIG. 1, the electric disc grinder 101 has a major axis direction as a front-rear direction (left-right direction in the figure), and an outer body is constituted by a main body portion 103 including a motor housing 105 and a gear housing 107. . The main body 103 corresponds to the “work tool main body” in the present invention. The motor housing 105 is formed in a substantially cylindrical shape, and a drive motor 111 is accommodated in the motor housing 105. The drive motor 111 corresponds to the “drive source” in the present invention. The drive motor 111 is arranged such that the rotation axis direction of the rotor 113 is the long axis direction of the electric disc grinder 101. A small bevel gear 117 is attached to the front end side (left side in the figure) of the motor shaft 115 of the drive motor 111, and a cooling fan 119 is attached so as to rotate integrally with the motor shaft 115. In the present embodiment, the rotation direction of the drive motor 111 is set to one direction.

  A power transmission mechanism 109 for transmitting the rotational output of the drive motor 111 to the grindstone 141 is accommodated in the gear housing 107 connected to the front end portion of the motor housing 105. The grindstone 141 corresponds to the “tip tool” in the present invention. As shown in FIG. 2, the power transmission mechanism 109 includes a small bevel gear 117 (see FIG. 1), a gear 121, a spindle 123, and a lock cam 151. The gear 121 corresponds to the “driving side rotating member” in the present invention, and the spindle 123 corresponds to the “driven side rotating member” in the present invention. It is assumed that the gear 121 driven by the drive motor 111 is rotated in the arrow direction (right rotation) shown in FIG.

  The gear 121 has teeth that are always meshed and engaged with the small bevel gear 117 (see FIG. 1) in the outer peripheral region, and is arranged so that the axial direction thereof is a direction perpendicular to the rotation axis of the drive motor 111, that is, the vertical direction. Is done. The spindle 123 is concentrically disposed through the shaft hole of the gear 121 and is fitted to the gear 121 so as to be relatively rotatable. The spindle 123 extends vertically and has a double-supported support structure that is rotatably supported by the gear housing 107 via bearings 125 and 126 (see FIG. 1) at the upper and lower portions thereof.

  As shown in FIG. 1, the tip (lower end) of the spindle 123 protrudes from the lower surface of the gear housing 107, and a grindstone mounting portion 131 having a two-surface width and a threaded portion is formed at the protruding end portion. The grindstone 141 is detachably mounted on the grindstone mounting portion 131 so as to be sandwiched from above and below via the mounting flanges 133 and 135 on the inner side (the upper surface of the grindstone) and the outer side (the lower surface of the grindstone). The inner mounting flange 133 located on the upper surface side of the grindstone 141 is attached to the grindstone mounting portion 131 through a two-surface width so as not to be relatively rotatable, and the outer mounting flange 135 located on the lower surface side is screwed into the screw portion. In this structure, the grindstone 141 is attached. The outer mounting flange 135 is a member having a screw hole, and is set so that the direction opposite to the rotation direction of the spindle 123 is the tightening direction. That is, it is set so as to be tightened when the grindstone 141 is driven to rotate. The rear half of the grindstone 141 is covered with a cover 143.

  As shown in FIGS. 9 and 10, the lock cam 151 is formed in a substantially cylindrical shape having a spline hole 151 a and is arranged concentrically with the gear 121 on the lower surface side which is one end portion of the gear 121 in the axial direction. Yes. The lock cam 151 is connected to a spline shaft portion 123 a formed on the spindle 123 by spline fitting, thereby rotating integrally with the spindle 123. As shown in FIG. 2, the gear 121 and the lock cam 151 are restricted from moving in the axial direction with respect to the spindle 123 by a lower bearing 126 and a washer 159 attached to the spindle 123 via a circlip 157. . The lock cam 151 has two claw portions 153 having a phase difference of 180 degrees in the circumferential direction on the outer peripheral surface thereof, and a phase difference of 90 degrees in the circumferential direction with respect to the claw portions 153 (therefore, each other). Two planar cam portions 155 (having a phase difference of 180 degrees) are provided. The claw portion 153 is provided so as to protrude in the radial direction with a predetermined length, and the planar cam portion 155 is formed by planes that are parallel to each other. The claw portion 153 of the lock cam 151 is provided to receive rotational force from the two claw portions 121a (see FIGS. 5 and 6) for power transmission provided on the gear 121 and transmit it to the spindle 123. A configuration for transmitting the rotational force will be described later.

  As shown in FIGS. 1, 2, and 3, a circular lock ring 161 is disposed between the gear 121 and the lower bearing 126 and on the outer periphery of the lock cam 151. The lock ring 161 has a plurality of protrusions 161a (see FIGS. 11 and 12) protruding radially on the outer periphery, and the protrusions 161a are recessed portions formed on the inner wall surface of the gear housing 107 corresponding to the protrusions 161a. 107a (refer FIG. 1) is engaged and the movement of the circumferential direction is controlled. The lock ring 161 has an inner peripheral surface having an inner diameter slightly larger than the outer diameter of the region including the claw portion 153 of the lock cam 151, and between the inner peripheral surface and the outer peripheral surface of the lock cam 151 and between the flat cam portion 155. A predetermined gap 156 is formed between them (see FIG. 3).

  In the gap 156 between the inner peripheral surface of the lock ring 161 and the flat cam portion 155 of the lock cam 151, a rolling element 165 formed in a cylindrical shape is disposed as shown in FIG. The rolling element 165 corresponds to a “lock member” in the present invention. The radial interval of the gap 156 formed by the flat cam portion 155 of the lock cam 151 and the inner peripheral surface of the lock ring 161 is maximum at the circumferential center portion of the flat cam portion 155 and is minimum at the end portion. The outer diameter of the rolling element 165 is set to be smaller than the maximum interval of the gap 156 and larger than the minimum interval portion. For this reason, the rolling element 165 allows rotation of the spindle 123 in a state where the rolling element 165 is positioned at the maximum interval portion of the gap 156 (the state shown in FIG. 3 (I)). ) (The state shown in (II) and (III) of FIG. 3), the flat cam portion 155 of the lock cam 151 and the inner peripheral surface of the lock ring 161 are engaged with each other, whereby the lock cam 151 and the lock ring are engaged. 161 is locked, and the rotation of the spindle 123 is fixed. That is, the lock cam 151, the lock ring 161, and the rolling member 165 constitute a spindle lock mechanism.

  On the lower surface side of the gear 121, four claw portions 121a and 121b (see FIG. 5) having a phase difference of 90 degrees from each other around the axis of the gear 121 are provided. Each claw portion 121a, 121b is formed in a cross-sectional arc shape extending in a predetermined length in the axial direction and circumferential direction of the gear 121, and as shown in FIG. 3, the claw portion 153 of the lock cam 151 and the flat cam portion 155. Between the outer peripheral surface of the lock cam 151 and the inner peripheral surface of the lock ring 161. Of the four claw portions 121a and 121b on the gear 121 side, one end portion (front side in the rotational direction) of the two claw portions 121a facing each other across the axis is the circumference of the claw portion 153 of the lock cam 151. Abutting on one end of the direction, a rotational force in the direction of the arrow (clockwise) is applied to the lock cam 151 to rotate the spindle 123 in the same direction. That is, the claw portion 121a of the gear 121 and the claw portion 153 of the lock cam 151 constitute a rotational force transmission mechanism that transmits the rotational force of the gear 121 to the spindle 123. Of the claw portions 121a and 121b of the gear 121, the two claw portions 121a contacting the claw portion 153 of the lock cam 151 correspond to the “power transmission portion” in the present invention, and the lock cam 151 and the claw portion 153 are the present invention. This corresponds to the “power receiving part”.

  As described above, in the synchronous rotation state in which the gear 121 and the spindle 123 rotate through the contact state between the claw portion 121a on the gear 121 side and the claw portion 153 on the lock cam 151 side, the other two gears on the gear 121 side are used. One end in the circumferential direction of the claw portion 121b abuts on the rolling element 165, and the rolling element 165 is held at the maximum gap portion of the gap 156 to avoid the engagement between the lock cam 151 and the lock ring 161. That is, synchronous rotation with the gear 121 of the spindle 123 is allowed.

  As shown in FIG. 3, the claw portion 153 of the lock cam 151 has a predetermined gap (hereinafter referred to as play) in the circumferential direction with respect to the claw portions 121 a and 121 b of the gear 121 positioned with the claw portion 153 interposed therebetween. That is, the lock cam 151 is allowed to rotate relative to the gear 121 in the circumferential direction within the range of play. For this reason, during the rotational operation of the spindle 123, when the rotational load on the spindle side (driven side) changes (increases or decreases), and accordingly the rotation of the spindle 123 precedes or delays the rotation of the gear 121, the gear The separation operation and the contact operation are repeated between the claw portions 121a and 121b on the 121 side and the claw portion 153 on the lock cam 151 side, and vibration or noise is generated. In order to avoid such a phenomenon and maintain the synchronous rotation of the spindle 123 and the gear 121, a synchronous rotation holding portion 171 that acts on a holding force so as to suppress the relative rotation between the gear 121 and the spindle 123 is provided.

  The synchronous rotation holding unit 171 includes a leaf spring 173 and a steel ball 175 (steel ball). The leaf spring 173 corresponds to the “first member” in the present invention, and the steel ball 175 corresponds to the “second member” in the present invention. The leaf spring 173 is a plate-like member made of an elastic material in which a spline hole 173a (see FIG. 13) is formed at the center, and is disposed on the upper surface of the gear 121 so as to face the spline shaft 123a of the spindle 123. Are connected by spline fitting (see FIG. 3). As shown in FIGS. 1 and 2, the leaf spring 173 is restricted from moving in the axial direction by a washer 159 attached to the spindle 123 via a circlip 157. The steel ball 175 is held by a ball mounting recess 121c (see FIG. 6) formed on the upper surface side of the gear 121, and a part of the steel ball 175 is engaged with a ball holding hole 173b provided in the leaf spring 173. A holding force (resistance force) is applied to suppress relative rotation (rotation in the preceding direction) of the spindle 123 with respect to the gear 121, and thereby, the claw portion 121 a on the gear 121 side and the claw portion 153 on the lock cam 151 side. Maintain a contact state.

  The electric disc grinder 101 according to the present embodiment is configured as described above. Next, the operation and usage will be described. When the motor shaft 115, the small bevel gear 117, and the gear 121 are rotated by energization driving of the drive motor 111, the two claw portions 121a of the gear 121 are connected to the lock cam 151 as shown in the lower side of FIG. Abutting on the claw portion 153, a rightward rotational force is applied to the lock cam 151, and the spindle 123 is rotated to the right. Further, the other two claw portions 121b of the gear 121 are simultaneously brought into contact with the rolling element 165, and the rolling element 165 is held at the maximum distance portion of the gap 156 between the flat cam portion 155 of the lock cam 151 and the inner peripheral surface of the lock ring 161. And rotate together. For this reason, the rolling element 165 does not bite between the lock cam 151 and the lock ring 161. At this time, as shown on the upper side of (I) of FIG. 3, a part of the steel ball 175 is engaged with the ball holding hole 173b of the leaf spring 173, and the claw portion 121a of the gear 121 and the claw of the lock cam 151 The contact state with the portion 153 is maintained. For this reason, the spindle 123 and the gear 121 are kept in a synchronized rotational state by suppressing the relative rotation between them, and the claw portions 121a and 121b of the gear 121 and the lock cam are based on the change in the rotational load on the driven side. Generation | occurrence | production of the phenomenon that a separation | spacing operation | movement and contact | abutting operation | movement are repeated between 151 claw parts 153 is avoided.

  Next, the case where the grindstone 141 is removed from the spindle 123 will be described. In this case, when a rotational force is applied clockwise (in the rotational direction of the spindle 123) to loosen the outer mounting flange 135 using a lock nut wrench (not shown) while the spindle 123 is stationary, a spline is applied to the spindle 123. The rotational force is transmitted to the leaf springs 173 connected via each other. At that time, the steel ball 175 is fitted in the ball holding hole 173b of the leaf spring 173, and the contact state between the claw portion 121a of the gear 121 and the claw portion 153 of the lock cam 151 is held, but the gear 121 is driven. Since it is connected to the armature of the motor 111 and has a rotational load, the leaf spring 173 rotates relative to the gear 121 clockwise with the spindle 123. As a result, as shown in FIG. 3 (II), the steel ball 175 comes out from the ball holding hole 173b through elastic deformation of the leaf spring 173 in the spindle axial direction (upward in FIG. 1). By the relative rotation of the spindle 123 and the gear 121, the lock cam 151 connected to the spindle 123 via the spline is rotated, and the claw portion 153 of the lock cam 151 is separated from the claw portion 121a of the gear 121. That is, the lock cam 151 rotates relative to the gear 121 clockwise. Due to this relative rotation, the rolling element 165 moves away from the claw part 121b of the gear 121 and moves in the movable region, so that the rolling element is located between the flat cam part 155 of the lock cam 151 and the inner peripheral surface of the lock ring 161. Biting of 165 occurs, and the rotation of the spindle 123 is fixed. Thereafter, by rotating the mounting flange 135 clockwise with respect to the fixed spindle 123, the mounting flange 135 can be removed from the grindstone mounting portion 131 of the spindle 123, and the grindstone 141 can be removed.

  Next, the case where the grindstone 141 is attached to the spindle 123 will be described. In the stationary state of the spindle 123 (the state (II) in FIG. 3), the grindstone 141 is fitted into the grindstone mounting portion 131 and the mounting flange 135 is rotated counterclockwise. 3, the leaf spring 173 rotates relative to the gear 121 counterclockwise together with the spindle 123 as shown in FIG. As a result, the steel ball 175 is fitted into the ball holding hole 173b of the leaf spring 173. At the same time, the lock cam 151 rotates counterclockwise with respect to the gear 121 together with the spindle 123, and accordingly, the rolling element 165 engages between the flat cam portion 155 and the inner peripheral surface of the lock ring 161, and the spindle 123 rotates. Is fixed. In this state, the grindstone 141 can be attached to the spindle 123 by tightening the attachment flange 135 with a predetermined strength.

  As described above, according to the present embodiment, when the grindstone 141 is removed from or attached to the spindle 123, when a rotational force (external force) is input from the spindle 123 side, the lock cam 151, the lock ring 161, and the rolling wheel 141 are rotated. A spindle lock mechanism constituted by the moving body 165 operates. That is, the rotation of the spindle 123 can be fixed without fixing the spindle 123 from the outside. For this reason, the operability of attaching / detaching the grindstone 141 can be improved.

  When the grindstone 141 is driven to rotate by the drive motor 111 via the power transmission mechanism 109, the gear 121 is interposed between the gear 121 and the spindle 123 via the synchronous rotation holding portion 171. A holding force acts on the spindle 123 to suppress relative rotation. For this reason, as a result of the relative rotation between the gear 121 and the spindle 123 being restricted by fluctuations in the rotational load on the driven side, the contact between the claw portions 121a and 121b of the gear 121 and the claw portion 153 of the lock cam 151 is prevented. Occurrence of vibration or abnormal noise due to repeated contact and separation can be prevented.

Now, according to the present embodiment, the spindle 123 penetrates the gear 121, and the both ends of the spindle 123 are supported by the bearings 125 and 126, so-called both-end support structure. For this reason, the transmission of the rotational force between the gear 121 and the spindle 123 can be performed in a stable state. The spindle 123 is configured to support the gear 121 so as to be relatively rotatable in a state where the spindle 123 penetrates the gear 121. For this reason, the so-called centering between the spindle 123 and the gear 121 is performed by the fitting of the spindle 123 and the gear 121. As a result, when the spindle 123 is assembled to the gear housing 107, the centering is performed. There is no need to think about it. For this reason, assembly property improves.
Further, by adopting a configuration in which both ends of the spindle 123 are supported, the transmission of rotational force is stabilized and the force applied to the gear 121 and the spindle 123 is equalized. Therefore, the claw portion 121a of the gear 121 and the claw portion of the lock cam 151 are provided. 153, or the lifetime of the structural members related to transmission of rotational force such as the rolling elements 165 can be improved.

  Furthermore, since the spindle 123 passes through the gear 121, when setting the synchronous rotation holding portion 171 between the gear 121 and the spindle 123, the setting position of the synchronous rotation holding portion 171 is set to the axis of the spindle 123. It can be set at any position in the direction. That is, according to the present embodiment, the synchronous rotation holding portion 171 is different from the gear lower surface side region where the mechanism for transmitting the rotational force of the gear 121 to the spindle 123 and the lock mechanism for fixing the rotation of the spindle 123 are set. It can arrange | position using the area | region of the gear upper surface side. As a result, it is not necessary to assemble a plurality of types of mechanisms in a limited space, which is effective in improving the overall assemblability. Moreover, in this Embodiment, it is the structure which arrange | positions the synchronous rotation holding | maintenance part 171 in the electric disc grinder 101 effectively using the empty area | region on the gear upper surface side which originally existed as a dead space, and enlarges a product. Without this, the synchronous rotation holding unit 171 can be set.

  Moreover, the synchronous rotation holding | maintenance part 171 which concerns on this Embodiment is a structure which acts on holding | maintenance force by engage | inserting (engaging) a part of steel ball 175 in the ball | bowl holding hole 173a of the leaf spring 173. In this way, a structure is obtained in which a holding force is obtained by engaging the leaf springs 173 and the steel balls 175 arranged in opposition to each other in the axial direction of the gear 121, with the direction orthogonal to the axial direction of the gear 121 as an engaging surface. Therefore, it is effective in shortening the axial length of the synchronous rotation holding portion 171 as compared with the configuration in which the axial direction of the gear 121 is the engaging surface.

(Second embodiment of the present invention)
Next, a second embodiment of the present invention will be described with reference to FIGS. 2nd Embodiment is related with the structure in the forward / reverse rotation model which can carry out the right rotation (forward rotation) and the left rotation (reverse rotation) of the grindstone 141 (refer FIG. 1) as a front-end tool, for example. In this embodiment, when the gear 121 is rotated to the right by the drive motor 111 (see FIG. 1), one of the two claw portions 121a and 121b and the two claw portions 121a facing each other across the rotation axis of the gear 121. Functions for transmitting the right rotational force, the other two two claws 121b function for holding the rolling element 165, and when the gear 121 is rotated counterclockwise, the functions of the claws 121a and 121b are reversed. That is, the other two claw portions 121b function to transmit the left rotational force, and the other two claw portions 121a function to retain the rolling element 165. The leaf spring 173 constituting the synchronous rotation holding portion 171 includes a ball holding hole 173b for right rotation and a ball holding hole 173c for left rotation. The right rotation ball holding hole 173b and the left rotation ball holding hole 173c are arranged at a predetermined interval in the circumferential direction. The interval between the claw portion 153 of the lock cam 151 and the claw portion 153 is as follows. This corresponds to the circumferential interval set between the claw portions 121a and 121b of the gear 121 arranged to be sandwiched.

  The present embodiment is configured in the same manner as the first embodiment except for the above configuration. FIG. 14 shows a case where the gear 121 driven by the drive motor 111 rotates to the right (thus, the grindstone 141 rotates to the right). At this time, as shown in FIG. 15I, the two claw portions 121a for right rotation of the gear 121 abut against the claw portion 153 of the lock cam 151, and the other two claw portions 121b of the gear 121 are rolling elements. The rolling element 165 is held at the maximum distance portion in the gap 156 between the flat cam portion 155 of the lock cam 151 and the inner peripheral surface of the lock ring 161. For this reason, the rolling member 165 does not engage between the flat cam portion 155 of the lock cam 151 and the inner peripheral surface of the lock ring 161, and the gear 121 and the spindle 123 are connected to the claw portion 121 a of the gear 121 and the claw portion 153 of the lock cam 151. Rotate together through the contact state. At this time, in the synchronous rotation holding portion 171, the steel ball 175 is fitted into the ball holding hole 173 b for the right rotation of the leaf spring 173, and a holding force is applied so as to suppress the relative rotation between the spindle 123 and the gear 121. As a result, the synchronous rotation state of the spindle 123 and the gear 121 is maintained regardless of the rotational load fluctuation on the driven side.

  When the grindstone 141 is removed after the grinding operation or the grinding operation with the right rotation by the grindstone 141, the mounting flange 153 (see FIG. 1) rotates in the direction of loosening (clockwise) when the spindle 123 is stationary. At this time, since the rotational load of the armature of the drive motor 111 is acting on the gear 121, the leaf spring 173 together with the spindle 123 is relative to the gear 121 as shown on the upper side of FIG. Rotate. The steel ball 175 held on the gear 121 side by this turning operation comes out from the ball holding hole 173b of the leaf spring 173 while elastically deforming the leaf spring 173 in the spindle axial direction (upward in FIG. 1). On the other hand, the relative rotation of the spindle 123 and the gear 121 causes the lock cam 151 connected to the spindle 123 via the spline to rotate as shown in the lower side of FIG. The claw portion 153 is separated from the claw portion 121a of the gear 121. That is, the lock cam 151 rotates relative to the gear 121 clockwise. Due to this relative rotation, the rolling element 165 moves away from the claw part 121b of the gear 121 and moves in the movable region, so that the rolling element is located between the flat cam part 155 of the lock cam 151 and the inner peripheral surface of the lock ring 161. Biting of 165 occurs, and the rotation of the spindle 123 is fixed. Thereafter, by rotating the mounting flange 135 clockwise with respect to the fixed spindle 123, the mounting flange 135 can be removed from the grindstone mounting portion 131 of the spindle 123, and the grindstone 141 can be removed.

  Next, the case where the grindstone 141 is attached to the spindle 123 will be described. In the stationary state of the spindle 123 (the state of (II) in FIG. 14), the grindstone 141 is fitted into the grindstone mounting portion 131 and the mounting flange 135 is rotated counterclockwise to be tightened. 14, the leaf spring 173 rotates relative to the gear 121 counterclockwise with the spindle 123, as shown in FIG. As a result, the steel ball 175 is fitted into the ball holding hole 173b of the leaf spring 173. At the same time, the lock cam 151 rotates counterclockwise with respect to the gear 121 together with the spindle 123, and accordingly, the rolling element 165 engages between the flat cam portion 155 and the inner peripheral surface of the lock ring 161, and the spindle 123 rotates. Is fixed. In this state, the grindstone 141 can be attached to the spindle 123 by tightening the attachment flange 135 with a predetermined strength.

  (I) of FIG. 15 shows a case where the grinding stone 141 is rotated counterclockwise to perform the grinding operation or the polishing operation. In this case, the gear 121 is rotated counterclockwise by the drive motor 111. At this time, if the steel ball 175 is fitted in the ball holding hole 173b for the right rotation of the leaf spring 173, the gear 121 is rotated relative to the spindle 123 in the left direction by the rotational load on the driven side. With the relative rotation, the steel ball 175 comes out of the ball holding hole 173b for the right rotation of the leaf spring 173 and then fits into the ball holding hole 173c for the left rotation (see the upper part of FIG. 15 (I)). At this time, the two claw portions 121b for left rotation of the gear 121 come into contact with the claw portion 153 of the lock cam 151, and the other two claw portions 121a come into contact with the rolling element 165. As a result, the rolling element 165 is held at the maximum interval portion in the gap 156 between the flat cam portion 155 of the lock cam 151 and the inner peripheral surface of the lock ring 161 (see the lower part of FIG. 15 (I)). For this reason, the rolling member 165 does not engage between the flat cam portion 155 of the lock cam 151 and the inner peripheral surface of the lock ring 161, and the spindle 123 rotates counterclockwise together with the gear 121. On the other hand, in the synchronous rotation holding portion 171, the steel ball 175 is fitted into the ball holding hole 173c for the left rotation of the leaf spring 173, and in this state, the relative rotation between the spindle 123 and the gear 121 is suppressed. A holding force is applied, whereby the synchronous rotation state of the spindle 123 and the gear 121 is maintained regardless of the rotational load fluctuation on the driven side.

  Next, when the grinding wheel 141 is removed after the grinding work or the grinding work by the left rotation by the grinding wheel 141, the spindle 123 rotates in the direction (clockwise) in the loosening state of the mounting flange 153 (see FIG. 1). At this time, as shown in FIG. 15 (II), the claw portion 153 of the lock cam 151 is in contact with the claw portion 121b for counterclockwise rotation of the gear 121, so that the armature of the drive motor 111 is opposed to the mounting flange 153. An external force (rotational force) exceeding the rotational load is applied. As a result, the lock cam 151 is rotated together with the gear 121, and accordingly, the rolling element 165 is engaged between the flat cam portion 155 and the inner peripheral surface of the lock ring 161, and the rotation of the spindle 123 is fixed. In this case, since the gear 121 and the lock cam 151 rotate together, the steel ball 175 is maintained in a state in which the leaf spring 173 is fitted into the ball holding hole 173c for left rotation. Thereafter, by rotating the mounting flange 135 clockwise with respect to the fixed spindle 123, the mounting flange 135 can be removed from the grindstone mounting portion 131 of the spindle 123, and the grindstone 141 can be removed.

  Next, when the grindstone 141 is attached to the spindle 123, the grindstone 141 is fitted into the grindstone mounting portion 131 and the mounting flange 135 is rotated counterclockwise in the stationary state of the spindle 123 (state (II) in FIG. 15). When a rotational force is applied to the spindle 123 along with the tightening, the leaf spring 173 rotates relative to the gear 121 counterclockwise with the spindle 123 as shown in FIG. 15 (III). As a result, the steel ball 175 comes out from the ball holding hole 173c for the left rotation of the leaf spring 173. Further, the lock cam 151 rotates together with the spindle 123 counterclockwise relative to the gear 121, and accordingly, the rolling element 165 is engaged between the flat cam portion 155 and the inner peripheral surface of the lock ring 161, and the spindle 123 rotates. Fixed. The grindstone 141 can be attached to the spindle 123 by tightening the attachment flange 135 in this state.

  As described above, according to the present embodiment, when the grindstone 141 is driven to rotate, the rotation is relative to the spindle 123 and the gear 121 via the synchronous rotation holding portion 171 regardless of whether the wheel is rotated clockwise or counterclockwise. The holding force for suppressing the rotation is applied, and the synchronous rotation of the spindle 123 and the gear 121 can be maintained regardless of the change in the rotational load on the driven side. Further, when the grindstone 141 is removed from or attached to the spindle 123, when a rotational force is input from the spindle 123 side, the spindle lock mechanism configured by the lock cam 151, the lock ring 161, and the rolling element 165 is operated to operate the spindle. The rotation of the spindle 123 can be fixed without fixing the 123 from the outside. For this reason, the operability of attaching / detaching the grindstone 141 can be improved. In addition, as in the first embodiment described above, the spindle 123 is configured to penetrate the center of the shaft of the gear 121, and the function and effect of this is the same as in the first embodiment.

In the present embodiment, the synchronous rotation holding portion 171 is arranged on the upper surface side of the gear 121. However, the structure arranged on the lower surface side of the gear 121, that is, a mechanism for transmitting the rotational force of the gear 121 to the spindle 123. The synchronous rotation holding unit 171 may be arranged in a region where a lock mechanism for fixing the rotation of the spindle 123 is arranged. In the embodiment, a cylindrical member is used as the rolling element 165, but the rolling element 165 may be formed of a steel ball.
In the present embodiment, the synchronous rotation holding portion 171 is configured by the leaf spring 173 and the steel ball 175 engaged with the ball holding hole 173b of the leaf spring 173. However, the present invention is not limited to this. That is, the gear 121 and the spindle 123 may be configured to apply a holding force capable of suppressing the relative rotation of the gear 121 and the spindle 123. For example, the gear 121 and the spindle 123 may be an elastic body such as rubber or a spring. A configuration in which the holding force is applied by two rubber elastically biased members contacting each other is conceivable. Accordingly, the ball holding hole 173b of the leaf spring 173 in the first embodiment or the two ball holding holes 173b and 173c for the right rotation and the left rotation of the leaf spring 173 in the second embodiment are eliminated, respectively. By using the spring property of the spring 173, the leaf spring 173 may be changed to a configuration that gives resistance to the steel ball 175 per surface.
Moreover, although this Embodiment demonstrated in the case of the electric disc grinder 101 used for a grinding operation | work or a grinding | polishing operation | work as an example of a working tool, it is not restricted to this, For example, like a screw-fastening tool, it is a tip tool. The present invention can be applied to any work tool that performs a predetermined machining operation by a rotating operation.

In view of the gist of the invention, the following aspects can be configured.
(Aspect 1)
“A work tool according to claim 4,
The first member is configured as a sphere provided on the driving-side rotating member, and the second member is configured as a plate-shaped member provided on the driven-side rotating member, and the sphere and the plate-shaped member A work tool that is provided with a holding force that suppresses relative rotation between the driving side rotating member and the driven side rotating member through engagement with a spherical body holding portion provided on the member. "
According to the first aspect of the present invention, a synchronous rotation holding unit having a simple structure can be provided.

It is a longitudinal section showing the whole electric disk grinder composition concerning a 1st embodiment. It is an expanded sectional view of a power transmission mechanism part. It is sectional drawing of the rotational force transmission part based on the cross-section instruction | indication line (AA line, BB line) of FIG. 2, a lock mechanism part, and a synchronous rotation holding | maintenance part, (I) is at the time of a process work, (II) is When the grinding wheel is removed, (III) shows when the grinding wheel is attached. It is a top view of a gear. It is a bottom view of a gear. It is sectional drawing of a gear. It is a front view of a spindle. It is a half-section top view of a spindle. It is a top view of a lock cam. It is sectional drawing of a lock cam. It is a top view of a lock ring. It is sectional drawing of a lock ring. It is a top view of a leaf spring. It is sectional drawing of the rotational force transmission part which concerns on 2nd Embodiment, a lock mechanism part, and a synchronous rotation holding | maintenance part, (I) is at the time of the process operation by the right rotation of a grindstone, (II) is at the time of removal of a grindstone, (III ) Indicates when the grindstone is attached. It is sectional drawing of the rotational force transmission part which concerns on 2nd Embodiment, a lock mechanism part, and a synchronous rotation holding | maintenance part, (I) is at the time of processing operation by the left rotation of a grindstone, (II) is at the time of removal of a grindstone, (III ) Indicates when the grindstone is attached.

101 Electric disc grinder (work tool)
103 Body 105 Motor housing 107 Gear housing 107a Recess 109 Power transmission mechanism 111 Drive motor (drive source)
113 rotor 115 motor shaft 117 small bevel gear 119 cooling fan 121 gear (drive side rotating member)
121a Claw portion 121b Claw portion 121c Ball mounting recess 123 Spindle (driven rotation member)
123a Spline shaft portion 125 Bearing 126 Bearing 131 Wheel mounting portion 133 Inner mounting flange 135 Outer mounting flange 141 Wheel (tip tool)
143 Cover 151 Lock cam 151a Spline hole 153 Claw part 155 Flat cam part 157 Circlip 159 Washer 161 Lock ring 161a Projection 165 Rolling body 171 Synchronous rotation holding part 173 Leaf spring 173a Spline hole 173b Ball holding hole 173c Ball holding hole 175 Steel ball

Claims (3)

A drive-side rotating member that is disposed on the work tool body and rotated by a drive source;
A driven-side rotating member that is disposed on the work tool main body and that is rotatably fitted coaxially to the driving-side rotating member in a state of passing through the rotation axis of the driving-side rotating member ;
A power receiving portion provided in a protruding shape in the radial direction on the driven side rotating member;
A power transmission unit that rotates together with the drive side rotation member, contacts the power receiving unit, and transmits the rotational force of the drive side rotation member to the driven side rotation member;
A tip tool that performs a predetermined machining operation by being rotationally driven through the driven side rotation member;
When the driving side rotating member and the driven side rotating member are synchronously rotated through a contact state between the power transmission unit and the power receiving unit, the driven side rotating member is rotated. And a lock member that fixes rotation of the driven side rotating member when the driven side rotating member rotates relative to the drive side rotating member,
The drive-side rotating member and the driven-side rotating member are kept in contact with the driving-side rotating member and the driven-side rotating member so that the driving-side rotating member and the driven-side rotating member maintain synchronous rotation through the contact state between the power transmission unit and the power receiving unit. When holding force is applied to suppress relative rotation and an external force in the circumferential direction exceeding the holding force is applied to the driven side rotating member, relative rotation of the driven side rotating member with respect to the driving side rotating member is allowed. synchronous rotation holding portion comprises al is that,
The power transmission portion and the power receiving portion are arranged on one end side in the axial direction of the driving side rotating member, and the synchronous rotation holding portion is arranged on the other end side in the axial direction of the driving side rotating member. A featured work tool. The work tool according to claim 1 ,
The synchronous rotation holding portion includes first and second members disposed in opposition to each other in the axial direction of the driven-side rotation member, and the first and second members are arranged to move relative to each other in the circumferential direction. It is configured to be connected to each other via a resistance portion on which a resistance force acts, whereby a holding force that suppresses relative rotation is applied to the driving side rotating member and the driven side rotating member. Work tool to do. The work tool according to claim 2,
The first member is configured as a sphere provided on the driving-side rotating member, and the second member is configured as a plate-shaped member provided on the driven-side rotating member, and the sphere and the plate-shaped member A work tool that is provided with a holding force that suppresses relative rotation between the driving side rotating member and the driven side rotating member through engagement with a spherical body holding portion provided on the member.

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