JP2017001163A - Rotary impact tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary impact tool in which a possibility such that a fastened screw cannot be loosened is hard to occur.SOLUTION: A rotary impact tool comprising a hammer 15 which has an impacting part 18 on a front side and is rotationally driven by a motor, and an anvil 22 which is rotatably located on a front co-axis of the hammer 15 and has an impacted part 23 which is impacted by the impacting part 18 on a rear side, in which when viewing from a rotary center line direction of the anvil 22, a distance of a rotary center of the anvil 22 at an impacted position of the impacted part 23 by the impacting part 18 when the hammer 15 is rotated in one direction is larger than that at an impacted position of the impacted part 23 by the impacting part 18 when the hammer 15 is rotated in the other direction.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a rotary impact tool used for a screw tightening operation and a tightened screw loosening operation.

  A rotary impact tool such as an impact driver includes a hammer that is rotationally driven by a motor, and an anvil that is rotatably arranged on the front coaxial side of the hammer and has a connecting portion to which a bit is connected on the front end side. On the front side of the hammer, a hitting portion for hitting a hitting portion formed on the rear side of the anvil is formed. The hammer hitting portion repeatedly hits the hit portion of the anvil to rotate the anvil, so that the screw can be firmly tightened or loosened by the bit connected to the anvil.

  As a configuration for driving the hammer so that the hammer hitting portion repeatedly hits the hit portion of the anvil, for example, there is a method using a cam groove. In this system, a hammer is fitted to the outer periphery of a spindle rotated by a motor so as to be rotatable and movable, and rotational driving force is applied to the hammer via a steel ball disposed in a cam groove formed on the outer periphery of the spindle. Communicated. A spring is disposed behind the hammer, and the hammer is positioned at a forward position where the hitting portion and the hit portion can be hit (contacted) by the urging force of the spring. In the tightening operation of the screw using such a rotary impact tool or the loosening operation of the tightened screw, when the rotational torque required for the rotation of the screw increases to a predetermined value or more, the shape effect of the cam groove causes the steel to After the hammer moves backward together with the ball against the biasing force of the spring, the contact state between the hitting part and the hitting part is once released, and then the hammering part is rotated again by the biasing force of the spring to advance the hitting part. By repeating the operation of abutting (striking) the striking portion, a large rotational torque can be applied to the anvil (see Patent Documents 1 and 2 below).

  In such a rotating impact tool, when the anvil is rotated in one direction (for example, clockwise) and in the other direction (for example, counterclockwise), the hammer's impact force is equal, The rotational torque applied to the anvil by hammering, that is, the torque to rotate the screw is equal.

JP 2000-42936 A Special table 2008-535675 gazette

  However, when the tightened screw is loosened, a rotational torque higher than that at the time of tightening may be required. In such a case, the tightened screw may be loosened using the rotary impact tool described above. It becomes difficult.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a rotary impact tool in which the problem that a tightened screw cannot be loosened hardly occurs.

  A rotary impact tool according to the present invention includes a hammer having a striking portion on the front side and rotationally driven by a motor, and a hit to be hit by the striking portion on the rear side of the hammer so as to be freely rotatable. An anvil having a portion, and when viewed from the direction of the rotation center line of the anvil, the hammer hits the hit position of the hit portion when the hammer rotates in one direction. The hit position of the hit portion by the hit portion when the hammer rotates in the other direction has a large distance from the center of rotation of the anvil.

  In the rotary impact tool according to the present invention, the rotation direction of the anvil when the hammer rotates in one direction may be a rotation direction in which a right screw is tightened.

  ADVANTAGE OF THE INVENTION According to this invention, the rotary impact tool which cannot generate | occur | produce the problem that the tightened screw cannot be loosened can be provided.

It is a side view of the rotary impact tool which concerns on this embodiment. It is sectional drawing of the rotary impact tool which concerns on this embodiment, Comprising: Illustration of a battery pack is abbreviate | omitted. It is a figure which shows the cross section AA in FIG. FIG. 3 is an enlarged view of a main part of a cross section BB in FIG. 2, where (a) shows a driving mode when a right screw is tightened, and (b) shows a driving mode when a right screw is loosened.

  Hereinafter, a preferred embodiment for carrying out the present invention will be described with reference to FIGS. In the following embodiments, a case where the present invention is applied to a hand-held electric impact driver will be described as an example. In addition, the following embodiments do not limit the invention according to each claim, and all combinations of features described in the embodiments are not necessarily essential to the solution means of the invention. .

  FIG. 1 is a side view of the rotary impact tool according to the present embodiment. FIG. 2 is a cross-sectional view of the rotary impact tool according to the present embodiment, and illustration of the battery pack is omitted. FIG. 3 is a view showing a section AA in FIG. FIG. 4 is an enlarged view of a main part of the cross section BB in FIG. 2, (a) shows a driving mode when the right screw is tightened, and (b) shows a driving mode when the right screw is loosened. ing. Further, in this specification, “front and rear” are defined and described as shown in FIG.

  As shown in FIGS. 1 to 4, a hand-held electric impact driver 1 that is a rotary impact tool according to the present embodiment includes a main body portion 10, a handle portion 30 protruding below the main body portion 10, and a handle And a battery pack 40 as a power source that is detachably disposed below the unit 30. A switch 31 is disposed on the upper front side of the handle portion 30, and the power of the battery pack 40 is disposed inside the main body portion 10 when the operator operates the switch 31 with a finger holding the handle portion 30. By being supplied to the motor 11, a bit (not shown) connected to the front end of the main body 10 can be rotated to perform a desired operation such as screw tightening.

  Inside the main body 10, a motor 11 as a drive source is disposed at the rear, and a speed reduction unit 12 as a planetary gear mechanism that decelerates the output of the motor 11 is disposed in front of the motor 11. A spindle 13 is connected in front of the speed reduction unit 12, and the output of the motor 11 is decelerated by the speed reduction unit 12 and transmitted to the spindle 13. A hammer 15 is fitted on the outer periphery of the spindle 13 so as to be rotatable and movable. A cam groove 14 is formed on the outer periphery of the spindle 13, and a groove 17 is formed on the inner periphery of the hammer 15. A steel ball 19 is interposed between the cam groove 14 and the groove 17, and the driving force from the spindle 13 is transmitted to the hammer 15 by the steel ball 19. A spring 21 is arranged behind the hammer 15, and the hammer 15 is urged forward by the spring 21.

  An anvil 22 is rotatably arranged on the front axis of the spindle 13 and the hammer 15. The front end side of the anvil 22 protrudes forward from the casing of the main body 10, and a connecting portion 24 for connecting a bit is provided here.

  A pair of striking portions 18 project forward from the outer periphery of the hammer 15 on the front end side. Further, as well shown in FIG. 4, a pair of hit portions 23 are radially formed on the rear end side of the anvil 22. When the hitting part 18 and the hit part 23 come into contact with each other, the rotational driving force transmitted from the spindle 13 to the hammer 15 via the steel ball 19 is transmitted to the anvil 22. Note that the hand-held electric impact driver 1 of the present embodiment can drive the anvil 22 forward and backward.

  When the hand-held electric impact driver 1 having the above-described configuration is screwed in with a right screw, as shown in FIG. 4A, the hammer 15 is struck by rotating in the direction of the arrow Da. The right side surface portion 18a of the portion 18 contacts and presses the left side surface portion 23b of the hit portion 23 of the anvil 22, and the anvil 22 is rotated, but when the rotational torque necessary for screw tightening exceeds a predetermined value, The steel ball 19 located on the front side of the cam groove 14 moves rearward against the urging force of the spring 21 together with the hammer 15 by the shape action of the cam groove 14. By this movement, the contact between the hitting portion 18 and the hit portion 23 is released. When the contact is released, the hammer 15 moves forward while moving the steel ball 19 along the cam groove 14 by the biasing force of the spring 21. At this time, the rotation of the hammer 15 in the direction in which the right screw is tightened by the shape action of the cam groove 14 is added to the rotation of the spindle 13. Then, the left side surface portion 23b of the hit portion 23 of the anvil 22 is hit by the right side portion 18a of the hit portion 18 of the hammer 15 rotating at high speed. By repeating this series of operations, the right screw can be firmly tightened.

  Further, when the right screw tightened with the hand-held electric impact driver 1 having the above-described configuration is to be loosened, as shown in FIG. 4B, the hammer 15 is struck by rotating in the direction of the arrow Db. The left side surface portion 18b of the portion 18 contacts and presses the right side surface portion 23a of the hit portion 23 of the anvil 22 to rotate the anvil 22, but the rotational torque necessary for loosening the right screw exceeds a predetermined value. Then, the steel ball 19 located on the front side of the cam groove 14 moves rearward against the urging force of the spring 21 together with the hammer 15 by the shape action of the cam groove 14. By this movement, the contact between the hitting portion 18 and the hit portion 23 is released. When the contact is released, the hammer 15 moves forward while moving the steel ball 19 along the cam groove 14 by the biasing force of the spring 21. At this time, rotation in the direction of loosening the right screw due to the shape action of the cam groove 14 is added to the hammer 15 in addition to the rotation by the spindle 13. The right side surface 23a of the hit portion 23 of the anvil 22 is hit with the left side portion 18b of the hit portion 18 of the hammer 15 rotating at high speed. By repeating this series of operations, the tightly tightened right screw can be loosened.

  When the hit portion 23 is hit by the hit portion 18, the hitting force of the hammer 15 is transmitted to the anvil as a rotating torque via the contact portion between the hit portion 18 and the hit portion 23. In this embodiment, this contact part is devised. The details will be described below.

  In the hand-held electric impact driver 1 that is the rotary impact tool according to the present embodiment, the impact portion 18 of the hammer 15 and the impact portion 23 of the anvil 22 when driven in the direction of tightening the right screw shown in FIG. 4a. When the right screw shown in FIG. 4 (b) is driven in the loosening direction, the hammering portion 18 of the hammer 15 and the hit portion 23 of the anvil 22 are in contact with each other. The distance Rb from the rotation center of the contact portion is set to be large. In any contact portion, the tangent lines La and Lb are set so as to pass through the center of rotation. Specifically, the right and left side surface portions 18a and 18b of the hitting portion 18 and the left and right side surface portions 23a and 23b of the hitting portion 23 are each suitably designed so that the above-described driving mode is achieved. .

  With this configuration, when the hammer 15 indicated by the symbol W in FIG. 4 has the same striking force regardless of the rotational direction, the rotational torque applied to the anvil when driven in the direction of loosening the right screw, That is, the product of the distance Rb and the striking force W is larger than the rotational torque applied to the anvil when driving in the direction in which the right screw is tightened, that is, the product of the distance Ra and the striking force W. Therefore, when the right screw is loosened, the rotational torque applied to the anvil increases, so that the problem that the tightened right screw cannot be loosened hardly occurs. In particular, the right-hand screw that is used most frequently is configured so that the rotational torque applied to the anvil is increased when it is loosened, so that versatility is high.

  As mentioned above, although preferred embodiment of this invention was described, the technical scope of this invention is not limited to the range as described in the said embodiment. Various modifications or improvements can be added to the embodiment.

  For example, in the above-described embodiment, the configuration in which the hammer 15 is driven so that the hitting portion 18 of the hammer 15 repeatedly hits the hit portion 23 of the anvil 22 uses the cam groove 14. It is not limited. For example, the hammer may be driven so that the hammer hitting portion repeatedly hits the hit portion of the anvil by the rotation direction switching control of the motor. Specifically, during the tightening or loosening operation of the screw, for example, when it is detected that the rotation of the screw (anvil) has stopped, the hammer is once rotated in the reverse direction by a predetermined amount and then rotated in the forward direction again. It can also be set as the structure which controls a motor so that the operation | movement which strikes an anvil may be repeated.

  Further, for example, in the above-described embodiment, the configuration is such that the rotational torque applied to the anvil increases when the right screw is loosened, but the case where the left screw is loosened is applied to the anvil. It is also possible to configure the rotational torque to be large.

DESCRIPTION OF SYMBOLS 1 Handheld electric impact driver, 10 main-body part, 11 motor, 12 deceleration part, 13 spindle, 14 cam groove, 15 hammer, 17 groove, 18 striking part, 18a right side part, 18b left side part, 19 steel ball, 21 spring, 22 anvil, 23 hit part, 23a right side part, 23b left side part, 24 connecting part, 30 handle part, 31 switch, 40 battery pack

Claims (2)

A rotation provided with a hammer having a striking part on the front side and rotationally driven by a motor, and an anvil having a striking part that is rotatably arranged on the front coaxial side of the hammer and is struck by the striking part on the rear side In the impact tool,
The striking part when the hammer rotates in the other direction with respect to the striking position of the striking part by the striking part when the hammer rotates in one direction when viewed from the rotation center line direction of the anvil. The rotary hitting tool is characterized in that the hitting position of the hitting part has a large distance from the center of rotation of the anvil.   The rotary impact tool according to claim 1, wherein a rotation direction of the anvil when the hammer rotates in one direction is a rotation direction in which a right screw is tightened.

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