JP2014151389A - Rotary impact tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a down-sized rotary impact tool.SOLUTION: A rotary impact tool comprises: a motor 11 acting as a drive source; a spindle 13 rotated by the motor 11; a hammer 15 fitted on the outer circumference of the spindle 13 and formed with a striking portion 18 on the front end side; and an anvil 22 born coaxially in front of the spindle 13 and formed on the rear end side with a radial struck portion 23, wherein the struck portion 23 includes a struck face 23a, in which a tangential line β of the striking position by the striking portion 18 passes through the rotation center of the anvil 22, and an overhang face 23b overhang outward with respect to the tangential line β on the radially inner side of the struck face 23a.

Description

  The present invention relates to a rotary impact tool capable of firmly tightening a screw while giving intermittent impact in a rotational direction in which the screw is tightened.

  A rotary impact tool such as an impact driver has a spindle that is rotated by a motor, a hammer that is fitted to the outer periphery of the spindle, and a connecting portion that is pivotally supported on the front coaxial axis of the spindle and to which a bit is connected on the front end side. Has an anvil. On the front end side of the hammer, a striking portion is formed which engages with a hit portion formed on the rear end side of the anvil. A cam groove is formed on the outer periphery of the spindle, and a rotational driving force is transmitted to the hammer via a steel ball disposed in the cam groove. A spring is disposed behind the hammer, and the hammer is positioned in a forward position where the hitting portion and the hit portion are engaged in a normal state by the biasing force of the spring. When tightening screws with this rotary impact tool, when the tightening torque increases, the hammer moves backward by the guidance of the steel ball rolling in the cam groove, and the relationship between the impacted part and the impacted part Once the match is released, the anvil can be intermittently imparted with a rotating striking force by repeating the operation of moving forward and engaging (striking) while rotating again by the biasing force of the spring.

  In order to convert the rotational impact force on the anvil into the tightening force of the screw without waste, Patent Document 1 listed below passes the hit portion (abutment portion) of the anvil with which the impact portion is engaged through the rotation center of the anvil. A configuration formed in a plane is disclosed, and in addition, in this configuration, the circumferential width of the hit portion becomes narrower toward the center of rotation and the strength is low, so that it is adjacent to the front of the hit portion. A configuration in which reinforcing ribs are provided is disclosed.

Special table 2008-535675 gazette

  However, as described above, when the reinforcing rib is provided on the anvil, a space for the reinforcing rib is required in the casing, which is an obstacle to downsizing the rotary impact tool.

  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 that can be reduced in size.

  The rotary impact tool according to the present invention includes a motor as a drive source, a spindle rotated by the motor, a hammer fitted on the outer periphery of the spindle and formed with an impact portion on the front end side, and coaxially in front of the spindle. And an anvil having a radially hit portion formed on the rear end side thereof, and the hit portion includes a hit surface through which a tangent of a hit position by the hit portion passes through the rotation center of the anvil. A projecting surface projecting outward with respect to the tangent line on the radially inner side of the hit surface.

  In the rotary striking tool according to the present invention, the striking portion includes an extension region in which a relief portion for avoiding interference with the projecting surface is formed on the radially inner side of the striking position with the striking surface. be able to.

  ADVANTAGE OF THE INVENTION According to this invention, the rotary impact tool which can implement | achieve size reduction can be provided.

It is a top 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. It is a figure which shows the cross section AA in FIG. It is a principal part enlarged view of the cross section BB in FIG.

  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 plan view of a rotary impact tool according to the present embodiment. FIG. 2 is a sectional view of the rotary impact tool according to the present embodiment. FIG. 3 is a view showing a section AA in FIG. 4 is an enlarged view of an essential part of a cross section BB in FIG. In addition, illustration of a battery pack is abbreviate | omitted in FIG. 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 A battery pack 40 is provided 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 portion of the main body portion 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 rotation and movement of the hammer 15 relative to the spindle 13 are restricted by the steel ball 19. A spring 21 is disposed behind the hammer 13, and the hammer 15 is urged forward by the spring 21.

  An anvil 22 is rotatably arranged on the front coaxial axis of the spindle 13. 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.

  On the front end side of the hammer 15, a pair of striking portions 18 project forward. Further, as shown in FIG. 4, a pair of hit portions 23 are formed radially on the rear end side of the anvil 22. The rotation driving force transmitted from the spindle 13 to the hammer 15 via the steel ball 19 is transmitted to the anvil 22 by engaging the hitting portion 18 and the hit target portion 23. Note that the rotary impact tool 1 of the present embodiment can be rotated forward and backward, and the impact portion 18 and the hit portion 23 are formed symmetrically. FIG. 4 shows the engaged state of the hitting portion 18 and the hit portion 23 when used in the forward rotation direction (direction in which the right screw is tightened) indicated by the arrow line α.

  When performing the screw tightening operation in the forward rotation direction with the rotary hitting tool 1 having the above-described configuration, the hitting portion 18 and the hit portion 23 are rotated, but the screw tightening torque has a predetermined value. If it exceeds, the steel ball 19 located on the front side of the cam groove 14 moves to the rear side against the urging force of the spring 21 together with the hammer 15. By this movement, the engagement between the hitting portion 18 and the hit portion 23 is released. When the engagement is released, the anvil 22 stops rotating and no torque is transmitted. Therefore, the hammer 15 moves forward while moving the steel ball 15 along the cam groove 14 by the biasing force of the spring 21. At this time, due to the shape of the cam groove 14, the hammer 15 is given rotation in the forward rotation direction. The hammer 15 moves forward while rotating in the forward rotation direction so that the hitting portion 18 engages or hits the hit target portion 23. By repeating this series of operations, the screw can be firmly tightened.

  A large impact load is applied to the striking portion 18 and the hit portion 23 during this engagement (striking). In this embodiment, the shape is devised to withstand this impact load. The shape will be described below.

  As shown in FIG. 4, the hit | damage part 23 of the anvil 22 equips the outer peripheral side with the hit | damage surface 23a which the hit | damage part 18 of the hammer 15 hits. The hit surface 23a is formed so that the tangent line β of the hit position by the hit portion 18 passes through the center of rotation of the anvil 22, so that the hit force by the hit portion 18 on the hit surface 23a is not wasteful. It is converted to rotational force. A projecting surface 23b projecting outward with respect to the tangent line β is formed on the radially inner side of the hit surface 23a. The hit surface 23a and the projecting surface 23b are connected by an R surface, and the radially inner end of the projecting surface 23b and the peripheral surface 23c are also connected by the R surface. Thus, by forming the projecting surface 23b on the inner side in the radial direction of the hit surface 23a, the circumferential width of the hit portion 23 is not narrowed toward the rotation center, and is sufficient to withstand the impact load. Has strength. Moreover, since the hit | damage surface 23a and the overhang | projection surface 23b and the overhang | projection surface 23b and the surrounding surface 23c are connected by the R surface, the stress concentration in a connection part can be avoided. Further, since it is possible to increase the strength without additionally forming a reinforcing rib in front of the hit portion 23, it is possible to avoid an increase in the dimension in the front-rear direction when the reinforcing rib is additionally formed, and it is possible to reduce the size of the apparatus. It becomes. In the present embodiment, the hit surface 23a and the overhanging surface 23b are formed as flat surfaces, but may be formed as curved surfaces.

  The striking portion 18 of the hammer 15 includes an extending region 18b that extends from the striking position 18a with the hit surface 23a further to the inside in the radial direction. In the extended region 18b, an escape portion 18c is formed to avoid interference with the projecting surface 23b. By providing the extended region 18b as described above, the striking portion 18 has a sufficient cross-sectional area to withstand an impact load.

  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 hitting portion 18 and the hit target portion 23 are each formed as a pair (two), but may be formed as one or three or more.

  It is apparent from the scope of the claims that the embodiments added with such changes or improvements are also included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Hand-held 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 striking position, 18b extension area, 18c relief part, 19 steel Sphere, 21 Spring, 22 Anvil, 23 Hit part, 23a Hit surface, 23b Overhang surface, 23c Circumferential surface, 30 Handle part, 31 Switch, 40 Battery pack

Claims (2)

A motor that is a driving source; a spindle that is rotated by the motor; a hammer that is fitted to the outer periphery of the spindle and has a striking portion formed on the front end side; In a rotary impact tool comprising an anvil formed with a hit portion,
The hit portion includes a hit surface in which a tangent of a hit position by the hit portion passes through the center of rotation of the anvil, and an overhanging surface protruding outward from the tangent on the radially inner side of the hit surface. A rotary impact tool characterized by comprising.   The said hit | damage part is provided with the extension area | region in which the escape part for avoiding interference with the said protrusion surface was formed in the radial inside of the hit | damage position with the said to-be-struck surface. The electric tool as described in.

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