JP2007152448A - Rotary impact tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a moderate impact timing in a state where an additional hammer is locked in a hammer. <P>SOLUTION: This rotary impact tool includes: the hammer 4 fitted to the outer periphery of a spindle 3; and a rotary impact mechanism 5 interposed between the spindle 3 and the hammer 4 for causing the hammer 4 to make composite movement of axial movement and circumferential movement, and engage a pawl of the hammer 4 with a pawl of an anvil 6 and apply rotary impact to the anvil 6. The rotary impact tool includes: the additional hammer 8 engaged and disengaged with and from the hammer 4; an operating part 9 for switching the additional hammer 8 between the locking position of locking with the hammer 4 and the separating position of separating from the hammer; and an adjusting mechanism for intensifying the energizing force of an energizing mechanism 7 for energizing the hammer 4 toward the anvil 6 by switching the additional hammer 8 from the separating position to the locking position. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a rotary impact tool called an impact wrench or an impact driver capable of impacting a rotation direction and firmly tightening a screw.

Conventionally, various rotary impact tools are known. For example, an impact wrench described in Patent Document 1 is known.
The impact wrench described in Patent Document 1 is interposed between a spindle rotated by a drive motor, an anvil arranged on the same axis of the spindle, a hammer fitted to the outer periphery of the spindle, and the spindle and the hammer. A rotary striking mechanism. When a torque exceeding a predetermined value is applied between the spindle and the hammer, the rotary impact mechanism causes the hammer to engage the anvil claw by performing a combined motion of axial movement and circumferential movement of a predetermined angle. Combined, it is configured to apply a rotating blow to the anvil. Further, the impact wrench has an additional hammer. The additional hammer is provided so as to be detachable from the hammer, and is configured to reinforce the rotation hitting by being locked to the hammer.
Japanese Patent Laid-Open No. 6-190741

However, the hammer moves in the axial direction at the time of rotary hitting using the force of the spring biased toward the anvil side. For this reason, when the additional hammer is locked to the hammer, the total weight is increased, or friction is generated between the hammer and the additional hammer, so that the amount of movement of the hammer in the axial direction at the time of rotary impact is shortened. Therefore, the timing of hitting is shortened, and the repetition of goo (when applying force) and van (when hitting) becomes the repetition of goo and van, and there is a problem that it is not possible to obtain an appropriate hitting timing to tighten the screw firmly there were.
Therefore, the present invention has an object to provide a rotary impact tool that has an additional hammer that is engaged and disengaged with respect to the hammer and can obtain an appropriate impact timing even when the additional hammer is engaged with the hammer. And

In order to solve the above-mentioned problems, the present invention is a rotary impact tool having a configuration as described in each claim.
According to the first aspect of the present invention, an additional hammer that is engaged with and disengaged from the hammer, an operation portion that switches between an engagement position where the additional hammer is engaged with the hammer and a separation position where the additional hammer is detached, And an adjustment mechanism for increasing the urging force of the urging mechanism that urges the hammer toward the anvil by moving the hammer from the disengagement position to the locking position.

Therefore, when the additional hammer is locked to the hammer, the hammer is biased toward the anvil with a stronger force than when the additional hammer is detached from the hammer. Therefore, when the additional hammer is locked to the hammer, the amount of movement of the hammer in the axial direction can be reduced, and the impact timing can be prevented from being shortened. For example, when the additional hammer is locked to the hammer, the weight of the additional hammer is added to the weight of the hammer, and the hammer is difficult to move in the axial direction while rotating. Alternatively, a sliding resistance is generated between the hammer and the additional hammer, and the hammer becomes difficult to move in the axial direction. However, since the urging force of the urging mechanism is increased, the amount of movement of the hammer in the axial direction is ensured. As a result, even when the additional hammer is locked to the hammer, an appropriate timing for hitting can be obtained. By obtaining an appropriate hitting timing, an appropriate torque and hitting can be applied to the screw, and the screw can be tightened or loosened.
Moreover, the adjustment can be made automatically by adjusting the position of the additional hammer.

According to the second aspect of the present invention, the biasing mechanism is interposed between the spindle and the hammer so as to bias the hammer toward the anvil, and between the additional hammer and the hammer. And a second spring to be mounted. The adjusting mechanism is provided in the additional hammer, and the second hammer in the free state is pushed toward the hammer by moving the additional hammer from the disengaged position to the locked position, and the second spring and the first spring are used to press the hammer. It is configured to urge toward the anvil.
Therefore, in a state where the additional hammer is detached from the hammer, the hammer is biased only by the first spring. In the state where the additional hammer is locked to the hammer, the hammer is biased by the first spring and the second spring, and the biasing force is increased.

According to the third aspect of the present invention, the biasing mechanism has a spring that is interposed between the additional hammer and the hammer and biases the hammer toward the anvil. The adjustment mechanism is provided on the additional hammer, and is configured to increase the biasing force of the spring that pushes the spring toward the hammer and biases the hammer toward the anvil by moving the additional hammer from the disengaged position to the locked position. ing.
Therefore, when the additional hammer is moved from the position where it is detached from the hammer to the position where it is locked, the biasing force of the spring is increased by the adjusting mechanism.

(Embodiment 1)
The impact driver 1 of Embodiment 1 which is an example of a rotary impact tool will be described with reference to FIGS.
As shown in FIG. 1, the impact driver 1 includes a drive motor 2 housed inside the rear side of the housing 10, a spindle 3 rotated by the drive motor 2, an anvil 6 arranged on the same axis as the spindle 3, A hammer 4 fitted to the outer periphery of the spindle 3 and an additional hammer 8 engaged with and disengaged from the hammer 4 are provided.

As shown in FIG. 1, the output shaft 11 of the drive motor 2 is connected to the spindle 3 via a planetary gear train 12 which is a power transmission mechanism.
The planetary gear train 12 has a pinion gear (sun gear) 13 provided on the output shaft 11, a plurality of planetary gears 14 that mesh with the pinion gear 13, and an internal gear 15 that meshes with the planetary gear 14. The internal gear 15 is fixed to a gear box 16 fixed to the housing 10, and each planetary gear 14 is attached to a support shaft 17 attached to the carrier portion 3 a of the spindle 3 protruding from the outer periphery of the rear end portion of the spindle 3. It is rotatably supported.

As shown in FIG. 1, the spindle 3 is disposed on the same axis as the output shaft 11, and the rear end outer peripheral portion of the spindle 3 is rotatably supported with respect to the gear box 16 via a bearing 18. Therefore, the spindle 3 is rotated by the drive motor 2 via the planetary gear train 12.
As shown in FIG. 2, a hammer 4 is fitted on the outer periphery on the front end side of the spindle 3, and a rotary striking mechanism 5 is provided between the hammer 4 and the spindle 3.

The rotary hitting mechanism 5 is a mechanism for applying a rotary hit to the anvil 6, and as shown in FIG. 2, a pair of V grooves 20 formed in the spindle 3 and a pair of engaging recesses formed in the hammer 4. 21 and a pair of balls 22 interposed between the V groove 20 and the engaging recess 21.
As shown in FIGS. 2 and 7, the V-groove 20 is formed in a V shape on the outer periphery of the spindle 3 with a semicircular cross section and inclined with respect to the rotation axis. The engaging recess 21 is formed in the inner peripheral surface of the hammer 4 in a semicircular cross section and in an inverted V shape in side view. Accordingly, the hammer 4 is connected to the spindle 3 via the rotary impact mechanism 5 so as to be movable by a predetermined amount in the axial direction and rotatable by a predetermined angle in the circumferential direction.

As shown in FIG. 2, a first spring 23 is interposed between the flange portion 4 c formed on the front end portion of the hammer 4 and the carrier portion 3 a formed on the spindle 3. The first spring 23 is a compression spring and forms one member of a biasing mechanism 7 that biases the hammer 4 toward the anvil 6.
A ball 19a and a washer 19b are provided between the first spring 23 and the carrier part 3a, and the first spring 23 is supported so as to be rotatable about the axis with respect to the carrier part 3a.

On the front end surface of the hammer 4, as shown in FIG. 2, a pair of claws 4 a protruding toward the anvil 6 side is provided. On the other hand, at the rear end portion of the anvil 6, a pair of claws 6 a that engage with the claws 4 a of the hammer 4 are projected.
The anvil 6 is rotatably supported via a bearing 33 on an impact case 29 attached to the front end portion of the housing 10. A socket 6 b is provided at the tip of the anvil 6. The socket 6b protrudes from the impact case 29, and a bit which is a tip tool is detachably attached thereto.

An additional hammer 8 is provided on the outer peripheral side of the hammer 4 as shown in FIG.
The additional hammer 8 is cylindrical and is movable in the axial direction with respect to the hammer 4. A plurality of internal teeth 8 a are formed on the inner peripheral surface of the additional hammer 8. The inner teeth 8a are fitted in the axial direction with respect to the plurality of outer teeth 4b formed on the outer peripheral portion of the hammer 4, and the inner teeth 8a cannot be rotated in the circumferential direction with respect to the outer teeth 4b by the fitting. It becomes movable. Therefore, the additional hammer 8 can be engaged with and disengaged from the hammer 4 by moving the additional hammer 8 in the axial direction with respect to the hammer 4.

On the inner peripheral surface of the rear end portion of the additional hammer 8, a flange 8 b is formed that projects from the center of the shaft as shown in FIG. 2, and a second spring 24 is interposed between the flange 8 b and the hammer 4. ing.
The second spring 24 is a compression spring and is disposed on the outer peripheral side of the first spring 23. As shown in FIG. 2, the second spring 24 is in a free state at the detached position where the additional hammer 8 is detached from the hammer 4. As shown in FIG. 3, the second spring 24 is pressed toward the hammer 4 by the flange 8b of the additional hammer 8 and elastically compressed at the locking position where the additional hammer 8 is locked to the hammer 4. The hammer 4 is urged toward the anvil 6 side. Accordingly, the second spring 24 forms a member of the biasing mechanism 7 that biases the hammer 4 toward the anvil 6 together with the first spring 23.

As shown in FIG. 2, an operation portion 9 for operating the position of the additional hammer 8 is connected to the additional hammer 8.
The operation unit 9 includes a cover 25 disposed on the outer peripheral surface of the impact case 29 and a screw 26 attached to the cover 25 as shown in FIGS.
The cover 25 has a circular arc cross section, is slidable with respect to the outer peripheral surface of the impact case 29, and covers the guide hole 32 formed in the impact case 29.
As shown in FIG. 5, the screw 26 has a leg portion 26 a that passes through the impact case 29 and the guide hole 32 of the impact case 29 and reaches the recess 8 c formed in the additional hammer 8.

Sliding members 27 and 28 are attached to the leg portion 26a as shown in FIG.
The sliding member 27 is cylindrical and is provided in the guide hole 32, and prevents the leg portion 26 a from rattling with respect to the guide hole 32.
The sliding member 28 has a rectangular cylindrical shape, and is attached to the distal end portion of the leg portion 26a rather than the sliding member 27, and has an internal thread portion screwed into the leg portion 26a on the inner peripheral surface. The sliding member 28 is provided in a recessed portion 8c formed in a concave shape over the entire outer periphery of the additional hammer 8, and slides relative to the recessed portion 8c.
The sliding member 28 has a diameter larger than that of the guide hole 32 and is configured to prevent the screw 26 from dropping from the impact case 29.

  As shown in FIG. 4, the guide hole 32 includes a separation position guide hole 32a extending in the axial direction, a connection horizontal hole 32b extending in the circumferential direction from the rear end portion of the separation position guide hole 32a, and a connection horizontal hole 32b. A locking position guide hole 32c that extends forward in the axial direction in parallel with the disengaging position guide hole 32a is continuously provided from the end portion. The locking position guide hole 32c extends forward from the disengagement position guide hole 32a, and allows the operation portion 9 to move forward to allow the additional hammer 8 to be engaged with the hammer 4.

  When the operating portion 9 is operated along the guide hole 32 and the screw 26 is positioned in the guide hole 32a for detachment position or the connecting lateral hole 32b, the additional hammer 8 is detached from the hammer 4 as shown in FIG. (Separation position). At this time, the second spring 24 is in a free state and does not urge the hammer 4 toward the anvil 6. Therefore, the hammer 4 is biased toward the anvil 6 only by the first spring 23.

When the operating portion 9 is operated to move the screw 26 to the front end of the locking position guide hole 32c as shown in FIG. 6, the additional hammer 8 moves forward as shown in FIG. (Locking position). The second spring 24 is pushed toward the hammer 4 by the flange 8b of the additional hammer 8 and is elastically compressed. Accordingly, the hammer 4 is biased toward the anvil 6 side by the second spring 24 and the first spring 23.
That is, the urging force of the urging mechanism 7 is increased by the second spring 24 being pushed by the hammer 4 by the flange 8b formed on the additional hammer 8 (adjustment mechanism).

  When the operation unit 9 is held at the position shown in FIG. 5, the screw 26 is fastened to the sliding member 28. As a result, the cover 25 is pressed against the impact case 29 by the head portion 26 b of the screw 26, and the operation unit 9 becomes immovable with respect to the impact case 29. Then, the additional hammer 8 is held in an axially immovable and rotatable state by the operating portion 9 at the locking position.

  The hammer 4 when the additional hammer 8 is in the disengaged position is urged toward the anvil 6 by the first spring 23 as shown in FIG. Therefore, the claw 4a of the hammer 4 and the claw 6a of the anvil 6 are engaged. The hammer 4 and the spindle 3 can be interlocked via a ball 22 as shown in FIGS. Therefore, when the tightening torque or loosening torque of the screw is small, the spindle 3, the hammer 4 and the anvil 6 rotate together.

  A large torque is applied to the anvil 6 in the final stage of the screw tightening work by the impact driver 1 or the first stage of the screw loosening work. Therefore, a large torque is applied between the hammer 4 engaged with the anvil 6 and the spindle 3 rotated by the drive motor 2. When a large torque is applied, the hammer 4 rotates in the direction of arrow A relative to the spindle 3 as shown in FIG. (When the screw is loosened, it rotates in the direction opposite to the direction of arrow A.) Then, the ball 22 moves along the V-groove 20 and the ball 22 pushes the engaging recess 21 so that the hammer 4 is first. Retreats in the axial direction against the spring 23.

  Then, the claw 4a of the hammer 4 is disengaged from the claw 6a of the anvil 6 (see FIG. 9), and the hammer 4 advances in the axial direction by the first spring 23 while rotating together with the spindle 3. And the nail | claw 4a contact | abuts to the nail | claw 6a of the anvil 6 in the circumferential direction (collision), and the hit | damage of a rotation direction is provided to the anvil 6. FIG. As a result, a rotational blow is repeatedly applied to the anvil 6.

  When the additional hammer 8 is moved from the disengaged position to the locked position, the urging force of the two springs of the first spring 23 and the second spring 24 is applied to the hammer 4 as shown in FIG. Therefore, when a large torque is applied between the hammer 4 and the spindle 3, the hammer 4 resists the two springs of the first spring 23 and the second spring 24 by the rotary impact mechanism 5 as shown in FIGS. And retreats in the axial direction while rotating. And the nail | claw 4a of the hammer 4 remove | deviates from the nail | claw 6a of the anvil 6 (refer FIG. 9).

  The hammer 4 rotates together with the additional hammer 8 while moving forward in the axial direction by the biasing force of the first spring 23 and the second spring 24, and the claw 4a contacts the claw 6a of the anvil 6 in the circumferential direction. (collide. Therefore, even when the additional hammer 8 is locked, the hammer 4 reliably moves forward in the axial direction, and the claw 4a comes into contact with the claw 6a of the anvil 6 with certainty.

The first embodiment is formed as described above.
That is, the impact driver 1 includes an additional hammer 8, an operation unit 9 that switches between a locking position where the additional hammer 8 is locked to the hammer 4 and a separation position where the additional hammer 8 is detached as shown in FIGS. An adjustment mechanism (8b) for increasing the urging force of the urging mechanism 7 that urges the hammer 4 toward the anvil 6 by changing the hammer 8 from the disengaged position to the locked position.

Therefore, when the additional hammer 8 is locked to the hammer 4, the hammer 4 is biased toward the anvil 6 with a stronger force than when the additional hammer 8 is detached from the hammer 4. For this reason, the hammer 4 is locked to the additional hammer 8, so that the amount of movement of the hammer 4 in the axial direction is reduced, and the timing of hitting can be prevented from being shortened. For example, when the hammer 4 is locked to the additional hammer 8, the weight of the additional hammer 8 is added to the weight of the hammer 4, and the hammer 4 is difficult to move in the axial direction while rotating. Alternatively, a sliding resistance is generated between the hammer 4 and the additional hammer 8 and the hammer 4 is difficult to move in the axial direction, but the biasing force of the biasing mechanism is increased, so that the amount of movement of the hammer 4 in the axial direction is ensured. Is done. As a result, even when the additional hammer 8 is locked to the hammer 4, an appropriate hitting timing can be obtained. By obtaining an appropriate timing for hitting, an appropriate torque and hitting can be applied to the screw, and the screw can be tightened or loosened.
Moreover, the adjustment can be automatically performed by adjusting the position of the additional hammer 8.

The urging mechanism 7 includes a first spring 23 and a second spring 24 as shown in FIGS. The adjusting mechanism (8b) is provided on the additional hammer 8, and the operating portion 9 moves the additional hammer 8 from the disengaged position to the locked position, thereby pushing the second spring 24 in the free state toward the hammer 4 and The hammer 4 is biased toward the anvil 6 by the second spring 24 and the first spring 23.
Therefore, in a state where the additional hammer 8 is detached from the hammer 4, the hammer 4 is biased only by the first spring 23. In the state where the additional hammer 8 is locked to the hammer 4, the hammer 4 is biased by the first spring 23 and the second spring 24, and the biasing force is increased.

(Embodiment 2)
The second embodiment will be described with reference to FIGS.
The second embodiment is formed in substantially the same manner as the first embodiment. However, the second embodiment is different from the first embodiment in that it has an urging mechanism 30 shown in FIG. 10 instead of the urging mechanism 7 of the first embodiment shown in FIG. Hereinafter, the second embodiment will be described focusing on the differences.

The impact driver 1 according to the second embodiment has an urging mechanism 30 including a spring 31 as shown in FIG.
The spring 31 is a compression spring, and is interposed between the flange 8 b formed on the additional hammer 8 and the hammer 4, and urges the hammer 4 forward toward the anvil 6.

  The hammer 4 when the additional hammer 8 is in the disengaged position is urged toward the anvil 6 by a spring 31 as shown in FIG. Therefore, when a large torque is applied between the spindle 3 and the hammer 4, the hammer 4 is retreated in the axial direction while rotating against the spring 31 by the rotary hitting mechanism 5, and the claw 4 a of the hammer 4 is moved to the anvil 6. Comes off the nail 6a. The hammer 4 rotates while being advanced in the axial direction by the spring 31, and the claw 4 a of the hammer 4 abuts (collises) with the claw 6 a of the anvil 6 in the circumferential direction.

  When the additional hammer 8 is set to the locking position, the internal teeth 8a of the additional hammer 8 engage with the external teeth 4b of the hammer 4 as shown in FIG. The spring 31 is pushed toward the hammer 4 by the flange 8b of the additional hammer 8 and is elastically compressed, and the force for biasing the hammer 4 of the spring 31 is increased (adjustment mechanism). Therefore, the hammer 4 when the additional hammer 8 is set to the locking position receives a larger biasing force from the spring 31 than when the additional hammer 8 is set to the release position.

  Therefore, when a large torque is applied between the spindle 3 and the hammer 4, the hammer 4 moves in the axial direction while rotating with the additional hammer 8 against the spring 31, so that the claw 4 a of the hammer 4 is moved to the anvil 6. Comes off the nail 6a. Then, using the biasing force of the spring 31, the hammer 4 rotates with the additional hammer 8 while moving forward in the axial direction, and the claw 4 a abuts (collises) with the claw 6 a of the anvil 6 in the circumferential direction.

As described above, the second embodiment is formed.
That is, the urging mechanism 30 has a spring 31. The adjustment mechanism (8b) is provided on the additional hammer 8 and is configured to push the spring 31 toward the hammer 4 and bias the hammer 4 toward the anvil 6 by moving the additional hammer 8 from the disengaged position to the locked position. The urging force of 31 is increased.
Therefore, when the additional hammer 8 is moved from the position where it is detached from the hammer 4 to the position where it is locked, the biasing force of the spring 31 is increased by the adjusting mechanism (8b).

(Other embodiments)
The present invention is not limited to the first and second embodiments, and may be the following modes.
(1) That is, Embodiment 1 has a first spring and a second spring, and is in a free state when the second spring releases the additional hammer. However, the second spring is elastically compressed when the additional hammer is in the release position, and the amount of elastic compression is increased by placing the additional hammer in the locking position, and the hammer is urged toward the anvil. The urging force may be increased.
(2) Although Embodiments 1 and 2 are impact drivers that are one of rotary impact tools, impact wrench may be used.
(3) The additional hammers of the first and second embodiments are configured to be disengaged by moving in the axial direction with respect to the hammer. However, the additional hammer may be configured to engage and disengage with respect to the hammer by moving in the radial direction.

2 is a partial cross-sectional view of an impact driver according to Embodiment 1. FIG. FIG. 2 is a partially enlarged view of FIG. 1. FIG. 3 is a partial cross-sectional view of an impact driver corresponding to FIG. 2 when an additional hammer is set to a locking position. FIG. 4 is a top view of the operation unit from the direction of arrow IV in FIG. 2. FIG. 5 is a partial cross-sectional view taken along line VV in FIG. 2. FIG. 5 is a top view of the operation unit corresponding to FIG. 4 when the additional hammer is set to the locking position by the operation unit. It is a schematic diagram of a rotation impact mechanism. It is a schematic diagram of a rotation impact mechanism. It is a schematic diagram which shows operation | movement of the nail | claw of a hammer with respect to the nail | claw of an anvil.

Explanation of symbols

1 ... Impact driver (rotary impact tool)
2 ... drive motor 3 ... spindle 4 ... hammer 5 ... rotary impact mechanism 6 ... anvil 7 ... biasing mechanism 8 ... addition hammer 8b ... ｂ (adjustment mechanism)
DESCRIPTION OF SYMBOLS 9 ... Operation part 10 ... Housing 16 ... Gear box 23 ... 1st spring 24 ... 2nd spring 25 ... Cover 27, 28 ... Sliding member 29 ... Impact case 30 ... Energizing mechanism 31 ... Spring 32 ... Guide hole

Claims (3)

A spindle rotated by a drive motor, an anvil arranged coaxially with the spindle, a hammer fitted to the outer periphery of the spindle, and interposed between the spindle and the hammer, the spindle and the hammer When a torque of a predetermined value or more acts between the hammer and the hammer, the hammer is engaged with the claws of the anvil by performing a combined movement of axial movement and circumferential movement. A rotary hitting tool having a rotary hitting mechanism for applying rotary hitting,
An additional hammer engaged and disengaged with respect to the hammer, an operation portion for switching between an engagement position where the additional hammer is engaged with the hammer and a disengagement position where the additional hammer is disengaged; A rotary impact tool comprising: an adjustment mechanism that increases an urging force of an urging mechanism that urges the hammer toward the anvil by being in a stop position. The rotary impact tool according to claim 1,
The biasing mechanism includes a first spring that is interposed between the spindle and the hammer and biases the hammer toward the anvil, and a second spring that is interposed between the additional hammer and the hammer. Have
The adjusting mechanism is provided on the additional hammer, and the second hammer in the free state is pushed toward the hammer by moving the additional hammer from the disengaged position to the locked position, and the second spring and the first A rotary impact tool, wherein the hammer is urged toward the anvil by a spring. The rotary impact tool according to claim 1,
The biasing mechanism has a spring that is interposed between the additional hammer and the hammer and biases the hammer toward the anvil.
An adjustment mechanism is provided on the additional hammer, and pushes the spring toward the hammer by moving the additional hammer from the disengaged position to the locked position, and biases the spring toward the anvil. A rotary impact tool characterized by being configured to reinforce.

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