JP4731162B2 - Electric tool - Google Patents

Description

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

  Japanese Patent No. 3174056 (Patent Document 1) discloses a disc grinder used for grinding a workpiece. A grindstone as a tip tool in a disc grinder is mounted on a tip portion of a spindle as a driven side rotating member so as to be sandwiched from both sides (upper and lower sides) in the axial direction via inner and outer mounting flanges. The outer mounting flange located on the lower surface side is a so-called tightening screw tightening structure that is screwed by turning in the opposite direction to the rotation direction of the spindle so as not to loosen during rotation of the grindstone. In the case of such a tightening screw tightening, the occurrence of loosening can be suppressed during the rotating operation of the grindstone, but the rotating operation of the grindstone is instantaneously performed by, for example, a mechanical spindle stop device or an electric brake of a motor. In such a case, the outer mounting flange may loosen due to its inertial force. For this reason, Patent Document 1 employs a configuration in which the tightening pressure of the grindstone by the inner and outer mounting flanges is automatically increased when rotation of the grindstone is stopped as a measure against loosening of the outer mounting flange.

However, in a power tool such as a disc grinder disclosed in Patent Document 1, in the method of suddenly stopping the rotation of the grindstone using the spindle stop device, a large impact is generated in the spindle stop device or the power transmission mechanism when the grindstone is stopped. Will be. As a result, there is a problem that the durability of these components is impaired, or the outer mounting flange is loosened, and there is still room for improvement in this respect.
Japanese Patent No. 3174056

  The present invention has been made in view of such a point, and an object of the present invention is to provide a technique effective in reducing an impact when stopping a tip tool in an electric tool including a rotary tip tool. To do.

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 main body , the motor accommodated in the main body , the driving side rotating member rotated by the motor, the driven side rotating member, and the driving side rotating member to the driven side rotating member. A power transmission unit that transmits power to the tool, a tip tool that performs a predetermined machining operation by being rotationally driven via a driving side rotating member and a driven side rotating member, a main body side member fixed to the main body part , An electric tool having a winding spring that is attached to the main body side member and locks the rotation of the driven side rotation member or releases the lock is configured. The “electric tool” in the present invention typically corresponds to a disk grinder that performs a grinding operation or a polishing operation on a workpiece by rotating a grindstone as a tip tool, but is not limited to a disk grinder. The power tool can be widely applied as long as it is a power tool that performs a predetermined machining operation on a workpiece by a tip tool that performs a rotating operation. Coil spring, the body-side member and the driven by relative rotation to one side of one of the winding direction (circumferential direction) with respect to their respective members together is mounted on the peripheral surface of the body side member and the driven side rotating member wound around the circumferential surface of the side rotational member to lock the rotation of the driven-side rotating member, the lock in the winding direction (circumferential direction) the other to release the winding by relative rotation on the side with the driven side rotating member of the Configured to release.

In the present invention, when the tip tool is rotationally driven, an external force is applied to the winding spring to bring the winding spring into a diameter-expanded state, thereby unlocking the driven side rotating member , and then via the power transmission unit. When the rotation of the driving side rotating member is transmitted to the driven side rotating member and the rotational driving of the tip tool is stopped, the action of the external force on the winding spring is released and the winding spring is fixed to the main body by this. It is set as the structure wound around the surrounding surface of a side member and a driven side rotation member . As the “power transmission unit”, a steel ball, a roller, a key, or the like can be preferably used.
According to the present invention, the rotation of the tip tool is locked using a winding spring, and when the tip tool is driven to rotate, an external force is applied to the winding spring to make the winding spring in an expanded state, thereby after unlocking of the driven-side rotating member has a configuration for transmitting the rotation of the driving-side rotating member to the driven side rotating member. For this reason, it is possible to smoothly transmit power from the driving side rotating member to the driven side rotating member. As an aspect of “applying an external force to the winding spring” in the present invention, typically, an aspect in which a force is applied so that the diameter of the winding spring spreads at one end of the winding spring is suitable. On the other hand, the rotation of the tip tool is stopped by releasing the action of external force on the winding spring. The winding spring placed in the expanded diameter state is wound around the main body side member and the driven side rotating member based on the release of the action of the external force. As a result, the driven-side rotating member can be braked and stopped. As described above, according to the system in which the driven side rotating member is braked using the winding spring, the driven side can be gently stopped as compared with the stopping system using, for example, a mechanical spindle stopping device. , The occurrence of impact when stopping can be reduced. As a result, the components of the power transmission mechanism can be protected from impact.

(Invention of Claim 2)
According to the second aspect of the present invention, the action of the external force on the winding spring and the rotation transmission action of the power transmission unit in the electric power tool of the first aspect are set in the circumferential direction of the drive side rotation member. . According to this configuration, it is possible to arrange the means for applying an external force to the winding spring and the power transmission unit for transmitting the power from the driving side rotating member to the driven side rotating member around the rotation axis of the rotating member. As a result, the power transmission mechanism can be made compact or the installation space can be saved.

(Invention of Claim 3)
According to the third aspect of the present invention, in the electric tool according to the second aspect, when the rotational drive of the tip tool is stopped, the winding operation and the winding release operation of the winding spring with respect to the main body side member and the driven side rotation member are performed. The configuration is performed alternately. According to such a configuration, the brake can be stopped while repeatedly acting on the driven-side rotating member, whereby the tip tool can be stopped more gently, and the impact can be reduced. It becomes effective.

(Invention of Claim 4)
According to a fourth aspect of the present invention, in the electric tool according to any one of the first to third aspects, at least two gears meshingly engaged with each other as a rotation transmitting element for transmitting the rotation of the motor to the driving side rotating member. When an external force is applied to the winding spring, the elastic force of the winding spring acts as a rotational force in the direction opposite to the rotational direction of the motor side gear with respect to the gear on the driving side rotating member. . According to this configuration, it is possible to absorb the backlash between the two gears and reduce the gear noise and vibration caused by the backlash by the elastic force of the winding spring.

(Invention of Claim 5)
According to the fifth aspect of the present invention, in the electric tool according to any one of the first to fourth aspects, the driven-side rotating member rotates in a direction opposite to the rotational direction in which the driven-side rotating member is rotated by the rotation of the driving-side rotating member. It is set as the structure which has a reverse rotation control means which controls so that it may not. As the “reverse rotation restricting means” in the present invention, typically, a one-way clutch can be preferably used. According to this configuration, the driven-side rotating member is locked by the winding spring in the rotation direction, and is locked by the reverse rotation restricting means in the direction opposite to the rotation direction. That is, since rotation in both directions of the driven-side rotating member can be regulated, for example, when a tip tool is attached or detached like a disc grinder, an external force acts on the driven-side rotating member in the direction of rotating the driven-side rotating member. By applying to such a power tool, it is possible to perform the attaching / detaching work of the tip tool without any trouble.

  According to the present invention, in an electric tool provided with a rotary tip tool, a technique effective in reducing the impact when stopping the tip tool is 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 an electric tool, a description will be given using a hand-held electric disc grinder used for grinding or polishing of various workpieces 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 shows the power transmission mechanism and the brake mechanism in an enlarged state. FIG. 3 sequentially shows the cross-sectional structures based on the cross-section indicating lines (AA line, BB line, CC line) in FIG. 2 from the upper side to the lower side of the drawing, and from the left side to the right side. The operation modes of the respective cross-sectional structures are sequentially shown, (I) is the initial state, (II) is the drive motor power-on operation (ON), (III) is the actual operation, (IV) is Indicates the power-off operation (OFF) of the drive motor.

  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 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 “motor” in the present invention. The drive motor 111 is mainly composed of a rotor 113 that is rotatably arranged in the motor housing 105 and a stator 115 that is fixed in the motor housing 105 by screws 114 as fastening means. The rotation axis direction of the rotor 113 is arranged so as to be 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 111a of the drive motor 111, and a cooling fan 119 is attached so as to rotate integrally with the motor shaft 111a.

  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. The power transmission mechanism 109 is mainly composed of a small bevel gear 117, a rotating cylinder 121, and a spindle 123. The rotating cylinder 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.

  As shown in FIG. 2, the rotating cylinder 121 integrally has a large bevel gear 122 that meshes with and engages with a small bevel gear 117 (see FIG. 1), and its axial direction is orthogonal to the rotational axis of the drive motor 111. It arrange | positions so that it may become a direction, ie, an up-down direction. The spindle 123 is penetrated through the cylindrical hole of the rotating cylinder 121 so that it can rotate relatively (thus, concentrically), and is rotatably supported by upper and lower bearings 125 and 126 (see FIG. 1). The rotation of the rotating cylinder 121 is transmitted via a plurality of (for example, two) steel balls (steel balls) 127. The steel ball 127 corresponds to the “power transmission unit” in the present invention. The steel ball 127 is disposed at a symmetrical position on the outer periphery of the spindle 123 with respect to the axis of the spindle 123 and is held in a state where movement in the circumferential direction and the axial direction is restricted. Grooves 129 (see a cross section CC in FIG. 3) extending in the circumferential direction with a predetermined length are provided on the inner peripheral surface of the rotating cylinder 121 symmetrically with respect to the axis of the rotating cylinder 121. A steel ball 127 is disposed in each groove 129 so as to be relatively movable in the circumferential direction, and one end portion (the rear end portion in the rotation direction of the rotating cylinder 121) 129a in the circumferential direction of the groove 129 engages with the steel ball 127. Thus, the rotation of the rotating cylinder 121 is transmitted to the spindle 123. That is, the rotating cylinder 121 and the spindle 123 are relatively rotated within a range corresponding to a gap C (see a section CC in FIG. 3) set between the steel ball 127 and the circumferential end of the groove 129. Is allowed.

  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 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.

  Next, a brake mechanism 151 for stopping the rotational drive of the spindle 123 will be described with reference to FIGS. The brake mechanism 151 locks the rotation of the spindle 123 or releases the lock, the first spring 153 fixed to the main body 103, and a steel ball (steel ball) so as to rotate integrally with the spindle 123. ) Primarily composed of a second ring 159 connected through 157 and an upper cylindrical portion 121a that integrally extends upward from the rotating cylinder 121. The first ring 155 corresponds to the “main body side member” in the present invention. The first ring 155 is fitted to the upper part of the outer periphery of the spindle 123 so as to be relatively rotatable, and a flange part 155a is formed at one end (upper end) in the axial direction so as to project to the outer periphery. On the other hand, the rotation restricting pin 156 protruding from the main body 103 (gear housing 107) is locked (fixed). The second ring 159 is fitted to the spindle 123 below the first ring 155 and assembled in a state where movement in the axial direction and the radial direction is restricted via the steel ball 157. As shown in FIG. 6, the assembly of the spindle 123 and the second ring 159 by the steel ball 157 is performed at a stage before the spindle 123 is assembled to the main body 103.

  The first ring 155 and the second ring 159 are arranged concentrically and have the same outer diameter and are opposed to each other in the axial direction. The upper cylindrical portion 121 a of the rotating cylinder 121 extends upward so as to be disposed outside the first ring 155 and the second ring 159. A cylindrical space is set between the inner peripheral surface of the upper cylindrical portion 121a and the outer peripheral surfaces of the first ring 155 and the second ring 159, and a winding spring 153 is disposed in the cylindrical space. Yes. That is, the winding spring 153 is attached to the outer peripheral surfaces of the first ring 155 and the second ring 159. 4 and 5, the winding spring 153 is a so-called torsion spring that receives a torsional moment about the axis of the winding spring 153, and has one end (upper end) 153a protruding in the radial direction, It is disposed in a notch 161 (see cross section AA in FIG. 3) extending in a circumferential direction formed in the upper cylindrical portion 121a, and the other end portion (lower end portion) 153b protrudes in the axial direction. It is fixed to the second ring 159.

  The winding spring 153 mounted as described above is in one of the winding directions (circumferential directions) between the first ring 155 fixed to the main body 103 (the rotating direction of the rotating cylinder 121 and the spindle 123). Is rotated around the outer peripheral surface of the first ring 155 and the second ring 159 to lock the rotation of the second ring 159 and the spindle 123, and is rotated relative to the other of the winding directions. The winding around the outer peripheral surfaces of the first ring 155 and the second ring 159 is released, and the lock of the second ring 159 and the spindle 123 is released. FIG. 3I shows an initial state. In this initial state, as shown in the upper stage (section AA) of FIG. 3I, one end 153a of the winding spring 153 is on one side in the circumferential direction of the notch 161 (the rear side in the rotational direction of the rotating body 121). It is separated from the notch end 161a. At this time, as shown in the lower part (cross-section CC) of (I) in FIG. 3, the steel ball 127 is placed at the position farthest from the one end 129a of the groove 129, and the gap C with the one end 129a is set. The distance between the one end 153a of the winding spring 153 and the notch end 161a of the notch 161 is set to be larger. 3 (I) is the initial state shown for convenience of explanation. Actually, the state shown in FIG. 3 (I) or the state shown in (II), that is, one end of the winding spring 153 is shown. Any of the states in which the notch 161a of the notch 161 is engaged (contacted) with 153a can be present. As shown in FIG. 1, the main body 103 is provided with a spindle lock device 171 that regulates the rotation of the spindle 123 when the grindstone 141 is replaced. The spindle lock device 171 is configured to lock the rotation of the rotary cylinder 121 by inserting the rod-like lock member 175 into the recess 121b of the rotary cylinder 121 by pushing the knob 173.

  This is configured as described above according to the present embodiment. In the initial state shown in FIG. 3I, the winding spring 153 has the inner peripheral surfaces thereof tightening the outer peripheral surfaces of the first ring 155 and the second ring 159, and the rotation of the spindle 123 is locked. When the power switch is turned on to energize the drive motor 111, the rotating cylinder 121 rotates from the motor shaft 111a of the drive motor 111 through the small bevel gear 117 and the large bevel gear 122 as shown in FIG. The cut-out end portion 161a of the rotating cylinder 121 engages with the one end portion 153a of the winding spring 153 (see the section AA). Since the rotating cylinder 121 and the spindle 123 can be rotated relative to each other within the gap C set between the groove 129 and the steel ball 127, the spindle 123 remains in the initial position. (See section CC). Then, when one end 153a of the winding spring 153 engaged with the notch end 161a of the rotating cylinder 121 is rotated, as shown in FIG. 3 (III), the winding spring 153 has an external force in the diameter increasing direction. Is entered. At this time, since the other end 153b of the winding spring 153 is fixed to the second ring 159 that has not yet rotated, the winding spring 153 expands in diameter, and thereby the outer peripheral surfaces of the first ring 155 and the second ring 159 The tightening of the spindle 123 is released, and the spindle 123 is unlocked. In this way, after the spindle 123 is unlocked, one end 129a of the groove 129 of the rotating cylinder 121 is engaged with the steel ball 127 (refer to the section CC in FIG. 3 (II)), and the spindle 123 rotates integrally with the rotating cylinder 121. That is, the grindstone 141 is rotationally driven, and the grinding work or the grinding work of the workpiece by the grindstone 141 is enabled.

When the power switch is turned off to stop the energization drive for the drive motor 111, both the rotating cylinder 121 and the spindle 123 rotate with inertial force, but the difference in frictional resistance (the rotational resistance of the rotor 113 of the drive motor 111 is reduced). The rotation of the spindle 123 becomes faster than the rotation of the rotating cylinder 121. Therefore, as shown in FIG. 3 (IV), the other end 153 b of the winding spring 153 fixed to the second ring 159 is pulled in the rotational direction of the second ring 159. As a result, the diameter of the winding spring 153 is reduced and wound around the outer peripheral surfaces of the first ring 155 and the second ring 159. Thus, the brake acts on the spindle 123.
If the rotation speed of the spindle 123 becomes slower than the rotation speed of the rotating cylinder 121 due to the braking action on the spindle 123, the notched end portion of the notch 161 of the rotating cylinder 121 again with respect to the one end portion 153a of the winding spring 153. 161a applies an external force in the diameter expansion direction. As a result, the diameter of the winding spring 153 is increased and the brake for the spindle 123 is released. As described above, the winding spring 153 alternately performs the brake action and the brake release action in response to the difference in rotational speed between the rotating cylinder 121 and the spindle 123, that is, the slow speed of the spindle 123 relative to the rotating cylinder 121. Then, the spindle 123 is stopped.

  As described above, according to this embodiment, when the grindstone 141 is driven to rotate, the lock of the spindle 123 by the winding spring 153 is released, and then the rotation of the rotating cylinder 121 is transmitted to the spindle 123 via the steel ball 127. be able to. For this reason, the power on the driving side can be transmitted smoothly and stably to the driven side. Further, according to the present embodiment, the elastic force of the winding spring 153 is applied to the rotating cylinder 121 from the rotating cylinder 121 until the grindstone 141 starts the rotating operation until reaching the steady rotation or in the steady rotating state. It is the structure which acts in the direction opposite to the rotation direction. For this reason, it is possible to absorb backlash between the large bevel gear 122 of the rotating cylinder 121 and the small bevel gear 117 on the motor side, which mesh with each other, and as a result, gear noise and vibration caused by the backlash can be prevented. Can be reduced.

  Further, in the present embodiment, when the rotational driving of the grindstone 141 is stopped, the brake is applied to the spindle 123 via the winding spring 153, so that a conventional electric brake or a mechanical spindle stop device is used. Unlike the method of instantaneously stopping the rotation of the grindstone, the grindstone 141 can be gently stopped. As a result, it is possible to reduce the occurrence of an impact at the time of stopping, and to protect the components of the power transmission mechanism 109 from the impact. In the case of the disc grinder 101, when the grindstone 141 is stopped, an inertial force acts on the outer mounting flange 135 that fixes the grindstone 141 in the loosening direction of the mounting flange 135. However, according to the present embodiment, as the grindstone 141 is gently stopped as described above, the inertial force acting on the mounting flange 135 is reduced, thereby preventing the mounting flange 135 from loosening. It becomes possible.

  In the present embodiment, the rotary cylinder 121 is provided with a notch 161, and one end 153 a of the winding spring 153 is engaged with the notch end 161 a of the notch 161, thereby increasing the diameter of the winding spring 153. In this configuration, an external force is input. In addition, the rotation of the rotating cylinder 121 is transmitted to the spindle 123 via a steel ball 127 disposed between the rotating cylinder 121 and the spindle 123. According to this configuration, the direction in which the external force that causes the winding spring 153 to increase in diameter and the direction in which rotation is transmitted from the rotating cylinder 121 to the spindle 123 are the circumferential directions around the axis of the spindle 123. As a result, means for applying an external force to the winding spring 153 and means for transmitting the rotation from the rotating cylinder 121 to the spindle 123 can be arranged around the rotation axis of the rotating member 121, respectively. The brake mechanism 151 can be made compact and the arrangement space can be saved.

  By the way, in the embodiment described above, when the grinding wheel 141 is attached to or detached from the grinding wheel mounting portion 131 of the spindle 123, the spindle 123 is attached to the other end 153b of the winding spring 153 in the direction of loosening the outer mounting flange 135. Thus, a rotational force in the direction of reducing the diameter of the winding spring 153 is input. For this reason, the rotational force in the direction of loosening the outer mounting flange 135 effectively locks the spindle 123 by the winding spring 153, and the outer mounting flange 135 can be moved without using the spindle lock device 171. It can be removed from the grindstone mounting part 131. On the other hand, with respect to the direction in which the outer mounting flange 135 is tightened, a rotational force acts on the other end 153 b of the winding spring 153 in the direction of expanding the diameter of the winding spring 153. The lock will be released.

  However, the direction in which the outer flange 135 is tightened when the grindstone 141 is attached to the grindstone mounting portion 131 is self-tightening during actual operation in which the grindstone 141 is rotationally driven. For this reason, it is not always necessary to firmly tighten the outer flange 135 in the mounting direction of the grindstone 141. In view of this, the spindle lock device 171 shown in FIG. 1 may be omitted. That is, it is possible to provide the disc grinder 101 having only the brake mechanism 151 using the winding spring 153 described in the first embodiment as a means for restricting the rotation of the grindstone 141, and thereby the spindle. The locking device 171 can be omitted.

(Second Embodiment)
In the second embodiment, as shown in FIG. 7, a one-way clutch 145 as a reverse rotation restricting means is provided at the upper end side shaft end portion of the spindle 123, whereby the spindle 123 is rotated for grinding work or polishing work. It is set as the structure controlled so that it may not rotate in the reverse direction. By providing such a one-way clutch 145, the spindle 123 can be locked in both the tightening direction and the loosening direction of the outer flange 135 by a combination with the locking of the spindle 123 by the winding spring 153. 171 (see FIG. 1) can be omitted, and the work of locking the spindle 123 is not required, so that workability is improved.

  Although the present embodiment has been described in the case of the disc grinder 101 used for grinding work or polishing work as an example of an electric tool, the present embodiment is not limited to this, and for example, by a rotating operation of a tip tool such as Marunoko. Any power tool that performs a predetermined processing operation can be applied.

In view of the gist of the invention, the following aspects can be configured.
(Aspect 1)
"The power tool according to any one of claims 1 to 3,
An electric tool characterized in that an external force acting on the winding spring is input through one end of the winding spring engaged with the driving side rotating member when the driving side rotating member rotates. "

(Aspect 2)
"The power tool according to any one of claims 1 to 3,
The power transmission unit is a steel ball disposed between an outer peripheral surface of the driven-side rotating member and an inner peripheral surface of the driving-side rotating member that is fitted to the outer periphery of the driven-side rotating member so as to be relatively rotatable. The steel ball is held in a state where movement in the circumferential direction is restricted with respect to either the driving side rotating member or the driven side rotating member, and a groove extending in the circumferential direction with respect to the other side. An electric tool characterized in that relative movement is possible at a predetermined angle around the axis of the rotating member. "

It is a longitudinal section showing the whole electric disk grinder composition concerning a 1st embodiment. It is an enlarged view of a power transmission mechanism and a brake mechanism. FIG. 3 is a cross-sectional view based on cross-section indicating lines (AA line, BB line, CC line) in FIG. 2, and (I) to (IV) show operating modes of the power transmission mechanism and the brake mechanism. . It is a side view which shows a winding spring. FIG. 5 is a view taken in the direction of arrow X in FIG. 4. It is a figure explaining the assembly | attachment of the steel ball which couple | bonds a spindle and a 2nd ring. It is sectional drawing which shows the electric disc grinder which shows 2nd Embodiment.

101 Disc grinder (electric tool)
103 Body 105 Motor housing 107 Gear housing 109 Power transmission mechanism 111 Drive motor (motor)
111a Motor shaft 113 Rotor 115 Stator 117 Small bevel gear 119 Cooling fan 121 Rotating cylinder (drive side rotating member)
121a Upper cylindrical portion 121b Recessed portion 122 Large bevel gear 123 Spindle (driven rotation member)
125 Bearing 126 Bearing 127 Steel ball (power transmission part)
129 Groove 129a One end 131 Grinding wheel mounting portion 133 Inner mounting flange 135 Outer mounting flange 141 Grinding wheel (tip tool)
143 Cover 145 One-way clutch 151 Brake mechanism 153 Winding spring 153a One end 153b Other end 155 First ring (main body side member)
155a Flange 156 Rotation restriction pin 157 Steel ball 159 Second ring 161 Notch 161a Notch end 171 Spindle lock device 173 Knob 173 Lock member

Claims (5)

The main body,
A motor housed in the main body ,
A driving side rotating member rotated by the motor;
A driven side rotating member;
A power transmission unit that transmits power from the driving side rotating member to the driven side rotating member;
A tip tool that performs a predetermined machining operation by being rotationally driven through the driving side rotating member and the driven side rotating member;
A body side member fixed to the body part ;
Wherein attached to the body side member locks the rotation of the driven-side rotating member, or has a coil spring that to release the lock, and
The winding spring is attached to the peripheral surfaces of the main body side member and the driven side rotation member , and is relatively rotated to one side of the winding direction with respect to each of the members, whereby the main body side member and the locks the rotation of the driven-side rotating member wound around the circumferential surface of the driven-side rotating member, the lock of the winding on the other side of one of the direction to release the attached said winding by relative rotation the driven side rotating member A power tool configured to release,
When the tip tool is rotationally driven, an external force is applied to the winding spring to bring the winding spring into a diameter-expanded state, thereby unlocking the driven-side rotating member , and then via the power transmission unit. When the rotation of the driving side rotating member is transmitted to the driven side rotating member and the rotational driving of the tip tool is stopped, the action of the external force on the winding spring is released, whereby the winding spring is moved to the main body. An electric tool characterized by being configured to wrap around a peripheral surface of a side member and the driven side rotating member . The electric tool according to claim 1,
An electric tool characterized in that an action of an external force on the winding spring and a rotation transmission action of the power transmission unit are set in a circumferential direction of the drive side rotation member, respectively. The electric tool according to claim 1 or 2,
When stopping the rotational drive of the tip tool, the winding operation and the winding release operation of the winding spring with respect to the main body side member and the driven side rotating member are the rotation of the driving side rotating member and the rotation of the driven side rotating member. The power tool is alternately performed based on the relative rotational difference between the two. The electric tool according to any one of claims 1 to 3,
It has at least two gears that mesh and engage with each other as a rotation transmitting element that transmits the rotation of the motor to the driving side rotation member, and when an external force is applied to the winding spring, the elastic force of the winding spring is An electric tool characterized by acting as a rotational force in the direction opposite to the rotational direction of the motor side gear with respect to the gear on the driving side rotating member side. The electric tool according to any one of claims 1 to 4,
An electric tool comprising reverse rotation restricting means for restricting the driven side rotation member from rotating in a direction opposite to a rotation direction driven to rotate by rotation of the driving side rotation member.

Images