JP2007118188A - Bit mounting device for rotary tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide steady technique of a bit which improves mounting and dismounting operationality of the bit, and is effective for increasing steady effect of the bit in the bit mounting device for a rotary tool. <P>SOLUTION: In the bit mounting device 20 for mounting the bit 14 to the tip end of an anvil 8, an annular spring mounting groove 27c is formed on the outer periphery of a spring holder 27, and an approximate C shape spring member 26 is fitted in the spring mounting groove 27c in a state where an energizing force (spring force) is applied in the direction to contract the diameter. An opening part 27d communicating with a corner part of a hexagon hole 27b where a base end part of the bit 14 is inserted is provided in the groove bottom of the spring mounting groove 27c. The spring member 26 regulates the movement of the bit 14 in the radial direction by engaging through the opening part 27d with respect to the corner part of the bit 14 inserted in the hexagon hole 27b. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a bit attaching device for attaching a driver bit or a socket type bit as a tip tool in a rotary tool such as a screw driver or an impact driver.

In general, this type of rotary tool includes a spindle that is rotated by a motor, and a bit attachment device for attaching a bit to the tip of the spindle. The bit attachment device includes an operation sleeve supported at the tip of the spindle so as to be movable in the axial direction. When the operation sleeve is retracted in the axial direction, a bit having a hexagonal cross section provided on the tip of the spindle. The bit can be inserted into and removed from the mounting hole. Then, when the operating sleeve is advanced in the axial direction (automatic return by spring force) with the hexagonal shaft portion of the bit inserted into the bit mounting hole, the driver bit mounted in the bit mounting hole is attached in a retaining state.
In the above bit mounting device, a rubber ring is mounted on the inner peripheral side of the bit mounting hole to prevent the bit mounting hole from swinging around the bit axis. By adopting a configuration in which the bit is inserted while spreading the bit, a steadying structure that suppresses the deflection of the bit by the elastic force of the rubber ring has been adopted.
JP-A-10-193278 Japanese Patent Laid-Open No. 10-315069 CD-ROM of Japanese Patent Application No. 3-99382 (Japanese Patent Application No. 5-39870) Microfilm of Japanese Utility Model No. 56-118547 (Japanese Utility Model Publication No. 58-27074) Microfilm of Japanese Utility Model No. 54-168609 (Japanese Utility Model Application No. 56-89411) Microfilm of Japanese Utility Model No. 57-153775 (Japanese Utility Model Publication No. 59-59276)

However, since the steady-state structure of the bit using the rubber ring uses the elasticity of the rubber, when the elasticity is set strongly, the frictional resistance of the rubber ring against the insertion / removal of the bit increases and the bit is attached / detached. On the other hand, when the elasticity is weakened, there is a problem that the holding force is lowered and a sufficient anti-rest effect cannot be secured.
The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to improve the detachability of the bit in the bit attachment device of the rotary tool and to prevent the bit from swinging. It is to provide a bit steadying technique effective in increasing the frequency.

In order to achieve the above object, a bit attachment device for a rotary tool according to the present invention has a configuration as described in each claim.
In the bit attachment device for a rotary tool according to claim 1, the spring member in a state in which an urging force is applied in a direction of contracting the diameter to a spring attachment groove formed on the outer periphery of the rotary shaft provided with the bit attachment hole. Is attached. The spring member has a plurality of openings formed so as to communicate the spring mounting grooves and the bit mounting holes in the circumferential direction in a scattered manner from the outer peripheral side with respect to the bit inserted into the bit mounting hole of the rotating shaft. By engaging, the radial movement of the bit is restricted. Here, the direction in which the diameter contracts means, for example, the direction in which the diameter of the spring member is reduced if the spring member is a single annular spring with a part of the circumferential direction cut away. In the case of a plurality of springs arranged at appropriate intervals on the line, it means a direction approaching the outer periphery of the bit. Moreover, the state to which the urging force is applied refers to a state in which a spring force is applied to the spring member in advance.
When the bit is inserted into the bit mounting hole of the rotating shaft, the spring member to which the urging force is applied in the direction of contracting the diameter is engaged with the outer periphery of the bit to restrict the radial movement, thereby Bit swings can be prevented. That is, according to the first aspect of the present invention, an urging force is applied to the spring member in the direction of contracting the diameter, and the bit is held by the urging force. Therefore, it is possible to easily obtain the holding force of the bit by the spring member necessary for the steadying of the bit, and the steadying effect can be improved.
The spring member is made of metal or resin. Therefore, the frictional resistance at the time of engagement or release with the spring member due to the insertion / extraction of the bit can be made much smaller than that of the conventional rubber ring. For this reason, it is possible to improve detachability when the bit is inserted into and removed from the bit mounting hole of the rotating shaft. Further, since the spring member is assembled from the outside, it is easy to process the spring mounting groove, and the spring member can be assembled from the outer peripheral side of the rotating shaft, so that the assembling property is improved.
In the invention according to claim 2, the spring member is attached to the spring mounting groove formed on the outer periphery of the rotating shaft in a state in which the biasing force is applied in the direction of contracting the diameter. In addition, the radial movement of the bit is restricted by engaging the flat part of the outer periphery of the bit inserted into the bit mounting hole of the rotating shaft via an inclusion. According to such a configuration, the engagement region between the inclusion and the bit can be widened, and a more stable steadying effect can be obtained.
In the bit attachment device for a rotary tool described in claim 3, a pressure member biased in the axial direction is attached to the back side of the bit attachment hole. The pressure member is configured to restrict radial movement while engaging the outer peripheral end portion in the axial direction of the bit inserted into the bit mounting hole and pressing the bit toward the retaining member side. According to such a configuration, the bit is restrained and stopped in the radial direction by the pressing member. The holding force for regulating the radial movement of the bit can be arbitrarily obtained by adjusting the axial biasing force applied to the bit. Further, the pressurizing member does not provide a frictional resistance against an operation of inserting and removing the bit from the bit mounting hole. For this reason, the attachment / detachment operability of the bit is improved.

Next, the 1st Embodiment of this invention is described based on FIGS. 1-3. This embodiment is applied to an impact driver as an example of a rotary tool. FIG. 1 shows the entire impact driver 1 in a partially broken state. FIG. 2 is an enlarged cross-sectional view of the bit attachment device, and FIG. 3 is a cross-sectional view taken along line AA of FIG. As shown in the figure, the impact driver 1 includes a spindle 4 that is rotated via a power transmission mechanism 3 including a planetary gear train using an electric motor housed in a housing 2 as a drive source. A hammer 9 for rotating and striking the anvil 8 concentrically arranged on the tip end side of the spindle 4 is fitted on the outer periphery on the tip end side of the spindle 4 so as to be rotatable and movable in the axial direction. ing. The anvil 8 is rotatably supported by a hammer case 6 joined to the housing 2 via a bearing 7, and a driver bit 14 (hereinafter simply referred to as a bit) that is a screw tightening tool can be attached to the tip of the anvil 8. Has been. Said anvil 8 respond | corresponds to the rotating shaft said by this invention.
A cam mechanism 12 composed of a combination of a cam groove 10 and a ball (steel ball) 11 is interposed between the spindle 4 and the hammer 9. The hammer 9 linked to the spindle 4 via the cam mechanism 12 directly transmits the rotation of the spindle 4 to the anvil 8 when the screw tightening resistance is small. ) When rotating together with the spindle 4 to move in the axial direction and impactably engage with the anvil 8 so as to transmit the rotational impact to the anvil 8.
That is, the hammer 9 is configured to perform a combined motion of a circumferential movement and an axial movement of a predetermined angle with respect to the spindle 4 and is always pressurized toward the forward direction (anvil 8 side) by the compression spring 13. Has been. On the other hand, the front end surface of the hammer 9 is provided with two claws 9a with a phase difference of 180 degrees in the circumferential direction, and correspondingly, the shaft end surface of the anvil 8 has a position of 180 degrees in the circumferential direction. Two claws 8a are provided with a phase difference.
Therefore, in a state where the screw tightening resistance exceeds a certain value, the hammer 9 advances while rotating by the pressure of the compression spring 13, and the claw 9a abuts (collises) with the claw 8a of the anvil 8 from the circumferential direction. Thereby, a blow in the rotational direction is given to the anvil 8. As a result, the screw is subjected to a rotational impact from the anvil 8 through the bit 14 and tightened. The hammer 9 after striking retreats in the axial direction while rotating in the direction opposite to the rotation direction of the spindle 4 against the compression spring 13 by the repulsive force at the time of striking. It advances while rotating with the applied pressure, and thereafter, the same striking operation as described above is repeated.

Next, the bit attachment device 20 for attaching the bit 14 to the anvil 8 of the impact driver 1 will be described. A bit mounting hole 8b for inserting a base end portion 14b on the insertion side of the bit 14 is formed on the distal end side of the anvil 8. In the present embodiment, the bit 14 forms a hexagonal column and has a cross driver portion 14c at the tip. Moreover, the groove part 14a for the steel ball 21 as a securing member assembled | attached to the anvil 8 side to fit is formed in the base end part side of the bit 14 over the perimeter.
The bit mounting hole 8 b of the anvil 8 is formed as a hexagonal square hole corresponding to the shape of the bit 14. The bit mounting hole 8b is formed at the center of the anvil 8, that is, on the rotation axis.
In addition, steel balls 21 are arranged at two locations in the radial direction on the front end side of the anvil 8. The steel balls 21 are movably accommodated in holding holes 8 c formed along the radial direction of the anvil 8, and are operated with respect to the bit mounting hole 8 b by the operation sleeve 22 disposed on the outer peripheral side of the tip end of the anvil 8. It is held so that it can go in and out. The diameter of the holding hole 8c is set so that the steel ball 21 does not fall off to the bit mounting hole 8b side.
The operation sleeve 22 is rotatably attached to the outer periphery of the anvil 8 and is restricted in the axial direction so that it cannot fall off by a retaining ring 23 and a flat washer 24. A compression spring 25 is interposed between the operation sleeve 22 and the flat washer 24, and the operation sleeve 22 is urged in the axial direction (left direction in FIG. 2) by the compression spring 25. A protrusion 22 a that protrudes inward in the circumferential direction corresponding to the steel ball 21 is formed on the inner peripheral side of the operation sleeve 22.
The operation sleeve 22 is always urged by the compression spring 25, and at that time, as shown in FIG. 2, the steel ball 21 is held at the position where it protrudes into the bit mounting hole 8b by the projection 22a. Therefore, in this state, if the bit 14 is inserted into the bit mounting hole 8b, the steel ball 21 is fitted into the groove portion 14a of the bit 14 and is prevented from coming off.
On the other hand, when the operating sleeve 22 is operated in the unclamping direction (rightward in FIG. 2) against the spring force of the compression spring 25 and the protrusion 22a is removed from the steel ball 21, the steel ball 21 is moved into the holding hole 8c. It becomes an immersive state. Therefore, in this state, the base end portion 14b of the bit 14 can be inserted into and extracted from the bit mounting hole 8b.

The bit attaching device 20 configured as described above can be easily attached / detached by inserting / removing the bit 14 in a state where the operation sleeve 22 is operated in the unclamping direction. The steel ball 21 can securely hold the bit 14 in the mounting position.
In addition, the bit attachment device 20 according to the present embodiment has a cross-section for steadying disposed on the back side of the bit mounting hole 8b in order to prevent the bit mounting hole 8b from rattling (shaking) around the axis of the bit 14. A circular spring member 26 is provided. As shown in FIG. 3, the spring member 26 is formed in an annular shape having a notch in a part in the circumferential direction, that is, in a substantially C shape, and is engaged with the outer periphery on the base side of the bit 14 so Regulate movement.
The spring member 26 is provided on the anvil 8 so as to penetrate the wall surface of the bit mounting hole 8b and slightly protrude toward the bit mounting hole 8b, and the protruding portion engages with a corner portion 14d of the base end portion 14b of the bit 14. Thus, the radial movement of the bit 14 is restricted.
In order to assemble the spring member 26 to the anvil 8, a cylindrical hole 8d is formed on the base side (spindle 4 side) of the anvil 8, and a spring holder 27 for receiving the spring member 26 is fitted into the cylindrical hole 8d. It is fixed. The spring holder 27 has a shaft hole 27a in which the tip shaft portion 4a of the spindle 4 is rotatably fitted on the base side, and a hexagon hole 27b that forms a part of the bit mounting hole 8b on the tip side. Yes. An annular spring mounting groove 27c is formed on the outer peripheral surface of the spring holder 27 at a portion corresponding to the hexagonal hole 27b, and the spring member 26 contracts in diameter in the spring mounting groove 27c, that is, the outer periphery of the bit 14. Are fitted in a state in which an urging force is applied in a direction approaching.
On the groove bottom surface of the spring mounting groove 27c, an opening 27d communicating with the hexagonal hole 27b is formed at a portion corresponding to each corner of the hexagonal hole 27b. That is, the spring mounting groove 27c and the hexagonal hole 27b are communicated with each other through six openings 27d in the circumferential direction. Therefore, a part of the inner periphery of the spring member 26 fitted in the spring mounting groove 27c protrudes from the opening 27d to the hexagonal holes 27b.

Therefore, when the bit 14 is inserted into the bit mounting hole 8 b, the corner portion 14 d of the base end portion 14 b of the bit 14 is inserted into the spring member 26 while expanding the spring member 26. At this time, since the spring member 26 has a circular cross section, the bit 14 can be inserted smoothly. The bit 14 inserted into the spring member 26 is engaged with the spring member 26 to restrict the radial movement, thereby preventing the bit 14 from swinging. The holding force of the bit 14 by the spring member 26 at this time can be appropriately set by an urging force (spring force) in a direction in which the diameter previously applied to the spring member 26 is contracted. Note that a gap is set between the inner peripheral surface of the cylindrical hole 8d of the anvil 8 and the outer periphery of the bit 14 so as to allow elastic deformation of the bit 14 in the expanding direction.
As described above, the bit attachment device 20 of the present embodiment is provided with the substantially C-shaped spring member 26 on the back side of the bit attachment hole 8b of the anvil 8, and the bit 14 inserted into the bit attachment hole 8b. The movement of the bit 14 in the radial direction is restricted by engaging with the outer peripheral surface of the bit 14, whereby the deflection of the bit 14 can be prevented.
In particular, according to the present embodiment, the spring member 26 can be attached to the annular spring attachment groove 27c in a state in which an urging force is applied in the direction of contracting the diameter. As a result, the bit 14 can be held by the urging force and the radial movement can be restricted. For this reason, it becomes possible to easily set the holding force required for steadying, and a bit mounting device with a high steadying effect for the bit 14 can be provided.
Further, since the spring member 26 is assembled to the spring mounting groove 27c from the outside, the spring mounting groove 27c can be easily processed, and the spring member 26 can be easily assembled to improve the assemblability. it can.
In the present embodiment, the spring member 26 is made of metal. For this reason, the frictional resistance when the bit 14 is inserted into and removed from the spring member 26 can be made much smaller than that of the conventional rubber ring. Accordingly, it is possible to improve the detachability when the bit 14 is inserted into and removed from the bit mounting hole 8b of the anvil 8, and the wear resistance is also improved as compared with the rubber ring.
As described above in detail, according to the present invention, in the bit attachment device for a rotary tool, the bit attachment / detachment operability is improved, and the bit steadying technique effective for enhancing the bit steadying effect is provided. can do.

Next, a second embodiment of the present invention will be described with reference to FIGS. The second embodiment is a modified example related to prevention of shake of the bit 14 in the bit attachment device 20. In the second embodiment, an annular, that is, substantially C-shaped leaf spring 28 is used as the spring member. The leaf spring 28 is fitted in an annular spring mounting groove 27c formed on the outer peripheral surface of the spring holder 27 with an urging force applied in a direction in which the diameter contracts. On the inner wall surface constituting the hexagonal hole 27b of the spring holder 27, an opening 27f is formed in every other three flat portions 27e out of the six flat portions, and a cylindrical pin 29 is formed in the opening 27f. Each is arranged. The pin 29 is arranged so that the axial direction thereof is parallel to the insertion / removal direction of the bit 14, and a part of the pin 29 protrudes into the hexagonal hole 27 b by being pressed by the leaf spring 28. The hole diameter of the opening 27f is set so that the pin 29 does not fall into the hexagonal hole 27b. Said pin 29 respond | corresponds to the inclusion said in Claim 2 of this invention.
As described above, in the second embodiment, the radial movement of the bit 14 is restricted by engaging the flat spring portion 14e of the bit 14 with the pin spring 29 as an inclusion interposed. It is configured. Other configurations are the same as those of the first embodiment described above.
Therefore, according to the bit attachment device 20 according to the second embodiment, it is possible to obtain the same operational effects as those of the first embodiment described above, and the configuration in which the pin 29 as an inclusion is interposed. Therefore, it is possible to employ a configuration in which the bit 14 is engaged with and held by the flat surface portion 14e, whereby the engagement area between the pin 29 and the bit 14 can be widened, and a more stable steadying effect can be expected.

Next, a third embodiment of the present invention will be described with reference to FIGS. The third embodiment is a modified example related to prevention of shake of the bit 14 in the bit attachment device 20. In the third embodiment, a cylindrical hole 8d is formed on the base side of the anvil 8 so as to communicate with the bit mounting hole 8b, and the bit holder 30 is accommodated in the cylindrical hole 8d so as to be movable in the axial direction. The bit holder 30 is pressurized to the tip side via a wave washer (corrugated plate) 32 supported by a cap 31 screwed into the base side of the cylindrical hole 8d.
That is, the bit holder 30 is in contact with the step surface with the bit mounting hole 8b in a state where an urging force is applied by elastic deformation of the wave washer 32. The bit holder 30 has a tapered engagement hole 30a on the distal end side, and the engagement hole 30a is engaged with the outer peripheral end portion in the axial direction of the bit 14 inserted into the bit mounting hole 8b. The bit 14 is pressed toward the steel ball 21 as a retaining member, and the radial movement is restricted. Others are configured in the same manner as in the first embodiment described above.
According to the third embodiment configured as described above, as in the first embodiment described above, the radial movement of the bit 14 inserted into the bit mounting hole 8b is restricted and the deflection is prevented. can do. In this case, since the bit 14 is pressed against the steel ball 21 as a retaining member by the bit holder 30, effective steadying is achieved in cooperation with the steel ball 21. Further, no resistance is applied to the insertion / removal of the bit 14 into / from the bit mounting hole 8b, and the insertion / removability of the bit 14 is improved. In the third embodiment, the bit 14 is configured to engage with the outer peripheral end portion of the bit 14 by the tapered engagement hole 30a. can get. For this reason, the steadying of the bit can be effectively realized.

In addition, this invention is not limited to the 1st-3rd embodiment mentioned above, In the range which does not deviate from the summary, it can change suitably.
For example, the steady-state structure of the bit 14 in the bit attachment device 20 can be changed as shown in FIG. 8 or FIG.
In the modification shown in FIG. 8, three planar cutout openings 27 g communicating with the hexagonal holes 27 b are formed at equal intervals in the circumferential direction on the groove bottom surface of the spring mounting groove 27 c formed in the spring holder 27. A substantially C-shaped spring member 26 having a circular cross-sectional shape and a part cut in the circumferential direction is fitted into the spring mounting groove 27c in a state where a biasing force (spring force) is applied in a direction in which the diameter contracts. The straight portion 26a of the spring member 26 is configured to be engaged with the three flat portions 14e of the bit 14 through the opening 27g.
In the modification shown in FIG. 9, three through holes 27h communicating with the hexagonal holes 27b are formed at equal intervals in the circumferential direction on the groove bottom surface of the spring mounting groove 27c formed in the spring holder 27. The spring mounting groove 27c is fitted with a substantially C-shaped leaf spring 28 having a flat cross-sectional shape and a part cut in the circumferential direction in a state where a biasing force (spring force) is applied in a direction in which the diameter contracts. Has been. Further, the leaf spring 28 is provided with three protrusions 28a protruding toward the inner diameter side at equal intervals in the circumferential direction, and the protrusions 28a are inserted into the bit mounting hole through the through hole 27h. It is set as the structure engaged with this plane part 14e. The modification described above can provide substantially the same operational effects as the above-described embodiment.
Further, in the modification shown in FIG. 9, the leaf spring 28 is further divided into three substantially V shapes each having a protrusion 28a, and the plurality of divided springs are preliminarily formed on the outer periphery of the bit 14. It is good also as a structure assembled | attached so that urging | biasing force (spring force) may be provided in the approaching direction (for example, attaching in the state which expanded V character).
In short, the spring member referred to in the present invention may be either a single member or a plurality of members, and holds the bit 14 from the outside when the bit 14 is not inserted into the bit mounting hole 8b. What is necessary is just to be attached to the anvil 8 as a rotating shaft so that force may be held.
In the above-described embodiment, the bit is steady at the back side of the bit mounting hole 8b, but may be changed to the configuration at the insertion port side. Further, although the figure shows the type of bit 14 in which the cross driver portion 14c is formed only at one end, it is needless to say that it can be applied to the type of bit having the cross driver portion 14c at both ends.
Further, in the above-described embodiment, the impact driver is described as the rotary tool. However, the present invention is not limited to this. For example, the present invention is applied to an impact wrench using a screw driver or a socket bit for tightening bolts and nuts as a tip tool. May be.

It is a partially broken front view which shows the impact driver which concerns on 1st Embodiment. It is sectional drawing which shows the bit attachment apparatus which concerns on 1st Embodiment. It is the sectional view on the AA line of FIG. It is sectional drawing which shows the bit attachment apparatus which concerns on 2nd Embodiment. It is the BB sectional view taken on the line of FIG. It is sectional drawing which shows the bit attachment apparatus which concerns on 3rd Embodiment. It is CC sectional view taken on the line of FIG. It is sectional drawing which shows the example of a change regarding the steadying of a bit. It is sectional drawing which shows the other example of a change regarding the steadying of a bit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Impact driver 4 ... Spindle 8 ... Anvil, 8b ... Bit mounting hole 14 ... Driver bit 20 ... Bit attachment apparatus 21 ... Steel ball 22 ... Operation sleeve 26 ... Spring member 27 ... Spring holder, 27b ... Hexagonal hole, 27c ... Spring attachment Groove, 27d ... opening 28 ... leaf spring 29 ... pin 30 ... bit holder, 30a ... engagement hole 32 ... wave washer

Claims (3)

A rotating tool bit mounting device for inserting a bit into a bit mounting hole of a rotating shaft and mounting the bit to the rotating shaft, wherein a biasing force is applied to a spring mounting groove formed on an outer periphery of the rotating shaft in a direction of contracting the diameter. A spring member is attached to the rotary shaft through a plurality of openings formed so as to communicate the spring attachment groove and the bit mounting hole in a dotted manner in the circumferential direction. A bit attaching device for a rotary tool, wherein the bit is inserted into the bit mounting hole to be engaged from the outer peripheral side to restrict the radial movement of the bit. A rotating tool bit mounting device for inserting a bit into a bit mounting hole of a rotating shaft and mounting the bit to the rotating shaft, wherein a biasing force is applied to a spring mounting groove formed on an outer periphery of the rotating shaft in a direction of contracting the diameter. The spring member is attached in a state where is provided, and the spring member is engaged with the flat portion of the outer periphery of the bit inserted into the bit mounting hole of the rotating shaft via an inclusion. A bit attachment device for a rotary tool, characterized by restricting the radial movement of the bit. A bit attachment device for a rotary tool that attaches the bit to the rotation shaft via a retaining member by inserting a bit into the bit attachment hole of the rotation shaft, and on the back side of the bit attachment hole, A pressing member biased in the axial direction is attached, and the pressing member engages with an outer peripheral end portion in the axial direction of the bit inserted into the bit mounting hole, thereby removing the bit from the retaining member. A rotating tool bit attachment device that restricts movement in a radial direction while pressing toward the side.

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