Power Tools

Abstract

To provide a drive tool that is capable of reducing vibration in use and can be compact in size.SOLUTION: A drive tool comprises: a main shaft 18 which is driven to rotate around an axis J as a center of rotation and has an eccentric part 25 which is centered at a position off the axis J; a movable body 38 which has a long hole 35 into which the eccentric part 25 is inserted, which is reciprocated linearly in an X-direction orthogonal to the axis J by rotating and moving around the axis J along with rotation of the main shaft 18 with the eccentric part 25 in contact with the long hole 35, and to which a tip tool can be attached; a counter weight 32 which is disposed so as to linearly reciprocate in the X-direction; and a transmission mechanism 49 which transmits movement force when the movable body 38 linearly reciprocates to the counter weight 32, causing the counter weight 32 to linearly reciprocate in the X-direction and in a direction opposite to the reciprocation direction of the movable body 38. The counter weight 32 is arranged on the axis J.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a driving tool that uses a tool tip, such as a file, by linearly reciprocating the tool tip. [Background technology]

[0002] A conventional power tool of this type is shown in, for example, Patent Document 1. This power tool includes a drive gear rotated by a motor, two eccentric cams arranged such that the long sides of the cam faces are on opposite sides of the drive gear and rotate with the rotation of the drive gear, a blade arbor connected to one of the eccentric cams, and a weight holding plate connected to the other eccentric cam.

[0003] The blade arbor has a tool attachment portion to which a tool can be detachably attached. The weight holding plate has a balance weight. When the motor is driven, the blade arbor and the balance weight perform a reciprocating linear motion so that they are positioned at opposite positions in the front-to-rear direction due to the action of two eccentric cams arranged so that the long sides of the cam surfaces are on opposite sides of each other. Therefore, the movement of the center of gravity position due to the reciprocating linear motion of the blade arbor in the front-to-rear direction is canceled by the balance weight, thereby reducing vibration due to the reciprocating linear motion of the blade arbor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5844202 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the power tool described above, although it is possible to reduce vibrations caused by the linear reciprocating motion of the blade arbor, the shaft that is the center of rotation of the eccentric cam and the balance weight are arranged side by side in the front-to-rear direction, which increases the size of the power tool in the front-to-rear direction. [Means for solving the problem]

[0006] The means for solving the above problems and their effects will be described below. The driving tool that solves the above problem comprises a main shaft that is driven to rotate about an axis and has an eccentric part whose center is located at a position offset from the axis, and a movable body having an insertion part into which the eccentric part is inserted, the eccentric part rotates about the axis while contacting the insertion part as the main shaft rotates, thereby moving back and forth in a linear motion perpendicular to the axis, and to which a tool tip can be attached, a counterweight arranged to be able to move back and forth in a linear motion in the orthogonal direction, and a transmission mechanism that transmits the moving force of the movable body when it moves back and forth in a linear motion to the counterweight, thereby moving the counterweight back and forth in a linear motion in the opposite direction to the movable body in the orthogonal direction, and the counterweight is arranged on the axis.

[0007] According to this configuration, the counterweight moves linearly back and forth in the orthogonal direction perpendicular to the axis of the spindle due to the force of the movement of the movable body in the orthogonal direction in the opposite direction to the movable body. Therefore, the inertial force caused by the linear reciprocating movement of the movable body can be canceled by the counterweight, so that the vibration generated by the linear reciprocating movement of the movable body can be reduced. In addition, since the counterweight is disposed on the axis of the spindle, the size of the driving tool in the orthogonal direction can be reduced compared to a case where the counterweight is disposed next to the spindle in the orthogonal direction. Therefore, the driving tool can be made smaller while reducing vibration during use.

[0008] In the above driving tool, it is preferable that the transmission mechanism is disposed between the movable body and the counterweight in the axial direction of the main shaft. According to this configuration, the movable body, the counterweight, and the transmission mechanism are arranged in a stacked manner in the axial direction of the main shaft, so that the size of the driving tool in the orthogonal direction can be further reduced.

[0009] In the above driving tool, it is preferable that the movable body includes a weight attachment portion to which a weight can be detachably attached. According to this configuration, even if the weight of the tool tip changes, the weight balance between the tool tip and the movable body and the counterweight can be easily maintained by simply attaching a weight of an appropriate weight to the movable body in accordance with the weight of the tool tip.

[0010] In the above driving tool, it is preferable that the eccentric portion is provided so that a distance from a center of the eccentric portion to the axis line in a radial direction of the main shaft is variable. According to this configuration, by changing the distance from the center of the eccentric portion to the axis of the main shaft in the radial direction of the main shaft, it is possible to change the amplitude of the linear reciprocating movement of the movable body.

[0011] In the driving tool, it is preferable that the movable body includes a shock absorbing portion that absorbs a shock when the shock is applied to the tool bit. According to this configuration, when an impact is applied to the tool tip attached to the movable body, the impact can be absorbed by the impact absorbing section, so that the impact can be prevented from being transmitted from the movable body side to the spindle side. Effect of the Invention

[0012] According to the present invention, it is possible to reduce the size while reducing vibration during use. [Brief description of the drawings]

[0013] [Figure 1] 1 is a perspective view of a driving tool according to an embodiment; [Diagram 2]FIG. 2 is a perspective view showing the inside of a main body case of the driving tool and its surroundings. [Diagram 3] Side view of the spindle. [Figure 4] FIG. 4 is a perspective view of the inside of the main body case as viewed from the rear side. [Diagram 5] FIG. [Figure 6] FIG. 4 is a perspective view showing the positional relationship between the counterweight and the transmission mechanism. [Figure 7] FIG. 13 is a plan view showing a state in which the moving body has moved forward. [Figure 8] FIG. 13 is a plan view showing a state in which the moving body has moved rearward. [Figure 9] FIG. [Figure 10] Bottom view of FIG. [Figure 11] FIG. 11 is a cross-sectional view showing a part of a modified example of the tool bit support portion. [Figure 12] 12 is a cross-sectional view showing a state in which the leaf spring in FIG. 11 is contracted. FIG. [Figure 13] FIG. 13 is a perspective view showing an installation state of a transmission mechanism according to a modified example. [Figure 14] FIG. 14 is a perspective view showing the transmission mechanism of FIG. [Figure 15] FIG. 11 is a cross-sectional view showing a main part of a moving body and its surroundings according to a modified example. [Figure 16] FIG. 16 is an exploded perspective view of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of a driving tool will be described with reference to the drawings. 1, the driving tool 11 comprises a block-shaped main body 12, a cylindrical grip 13 connected to an upper part of one side of the main body 12, and a cylindrical tool tip support 14 located at the lower part of the side of the main body 12 opposite to the side to which the grip 13 is connected and extending straight out from within the main body 12. The tip of the tool tip support 14 is provided with a tool tip attachment 16 to which a tool tip 15, such as a file or saw, can be detachably attached.

[0015] In the following description, the front-rear direction of the driving tool 11 in Fig. 1 where the tool attachment part 16 is located is defined as the front, the left-right direction is defined as the Y, and the up-down direction (vertical direction) is defined as the Z. The X, Y, and Z directions are perpendicular to each other. Therefore, the tool attachment part 14 and the grip part 13 described above both extend in the X direction.

[0016] 1 and 2, the main body 12 includes a main body case 17 and a main shaft 18 that extends in the Z direction and is housed in the main body case 17. The main body case 17 includes an upper case 19, a middle case 20 that is arranged below the upper case 19, and a lower case 21 that is arranged below the middle case 20. The upper case 19 and the middle case 20 support the main shaft 18 rotatably about an axis J that extends in the Z direction.

[0017] A first bevel gear 22 that rotates together with the main shaft 18 about the axis J is provided at the center of the main shaft 18 in the Z direction. A second bevel gear 23 that rotates about an axis extending in the X direction is provided at the end of the gripper 13 on the side of the main body 12. The diameter of the second bevel gear 23 is smaller than the diameter of the first bevel gear 22. A connection part 24 is provided at the end of the gripper 13 opposite the side of the main body 12 to connect with the tip of an air hose (not shown) extending from an air compressor (not shown).

[0018] A drive mechanism (not shown) is provided within the grip portion 13, which uses compressed air supplied from an air compressor (not shown) via an air hose (not shown) and a connection portion 24 to rotate the second bevel gear 23. When the second bevel gear 23 is rotated, the rotational force of the second bevel gear 23 is transmitted to the main shaft 18 via the first bevel gear 22, and the main shaft 18 is rotated about its axis J. In this case, since the diameter of the second bevel gear 23 is smaller than the diameter of the first bevel gear 22, the rotational speed of the first bevel gear 22 and the main shaft 18 is slower than the rotational speed of the second bevel gear 23.

[0019] 2 and 3, a cylindrical eccentric portion 25 having a center located at a position shifted by a distance D from the axis J in the radial direction of the main shaft 18 is provided at the lower end of the main shaft 18. In this embodiment, the eccentric portion 25 is, for example, composed of a cylindrical protrusion 26 integrally formed on the lower surface of the main shaft 18 and an annular bearing 28 in which an inner ring 27 is fitted onto the protrusion 26 by interference fit. The bearing 28 has a structure in which a plurality of balls (not shown) are arranged between the inner ring 27 and an outer ring 29, so that the outer ring 29 rotates relative to the inner ring 27.

[0020] The center of the convex portion 26 coincides with the center of the bearing 28. The axis J of the main shaft 18 and the axis of the eccentric portion 25 are parallel to each other. Therefore, when the main shaft 18 rotates about the axis J, the eccentric portion 25 moves along a circular orbit centered on the axis J of the main shaft 18. A balance weight 30 for balancing the rotation of the main shaft 18 is provided at a position at the upper end of the main shaft 18 that is shifted 180° from the eccentric portion 25 about the axis J.

[0021] 1 and 2, a substantially rectangular movable plate 31 is disposed at a position corresponding to the lower end of the main shaft 18. A substantially rectangular counterweight 32 is disposed below the movable plate 31 so as to be stacked on top of the movable plate 31. In other words, the counterweight 32 is disposed on the axis J of the main shaft 18. A pair of rectangular guide plates 33 extending in the X direction are disposed on both sides of the movable plate 31 and the counterweight 32 in the Y direction so as to sandwich them. The pair of guide plates 33 are fixed to the lower case 21.

[0022] Guide grooves 34 extending in the X direction are formed on the inner surfaces of the pair of guide plates 33 so as to be aligned vertically. That is, two guide grooves 34 are formed on each inner surface of the pair of guide plates 33. Both ends of the movable plate 31 in the Y direction are slidably inserted into the upper guide groove 34 of the pair of guide plates 33. Both ends of the counterweight 32 in the Y direction are slidably inserted into the lower guide groove 34 of the pair of guide plates 33. Therefore, the movable plate 31 and the counterweight 32 are supported by the pair of guide plates 33 so as to be able to move linearly back and forth in the X direction, which is a direction perpendicular to the axis J of the main shaft 18.

[0023] 2 and 4, a long hole 35 extending in the Y direction as an example of an insertion portion into which the eccentric portion 25 is inserted is formed penetrating the center of the moving plate 31. The length of the long hole 35 in the Y direction is longer than the diameter of the eccentric portion 25, and the length in the X direction is approximately the same as the diameter of the eccentric portion 25. When viewed from the Z direction, the contours of the long hole 35 on both sides in the Y direction form a semicircular arc shape curved so as to bulge outward in the Y direction, and the contours of both sides in the X direction form straight lines extending in the Y direction.

[0024] A block-shaped protruding portion 36 protruding forward is provided at the center of the front end of the movable plate 31 in the Y direction. A lower portion of the protruding portion 36 protrudes downward from the lower surface of the movable plate 31 and extends to the vicinity of the long hole 35. A base end side of the tip tool support portion 14 having a tip tool attachment portion 16 (see FIG. 1) provided at its tip side is connected to a hole 37 on the front surface of the protruding portion 36. In this embodiment, a movable body 38 is configured by the movable plate 31, the tip tool support portion 14, and the tip tool attachment portion 16 (see FIG. 1).

[0025] 2 and 5, a step 39 is formed in the center of the upper surface of the counterweight 32 in the X direction. The step 39 extends in an arc shape, curving such that the center in the Y direction bulges forward. The height of the upper surface of the counterweight 32 in the area forward of the step 39 is higher than the height of the area rearward of the step 39. A groove 40 extending in the X direction is formed in the center in the Y direction of the area forward of the step 39 on the upper surface of the counterweight 32.

[0026] The groove 40 extends from the step 39 on the upper surface of the counterweight 32 to the front end. The groove 40 accommodates the lower part of the protrusion 36 of the moving plate 31. The height of the bottom surface of the groove 40 is slightly higher than the height of the area on the upper surface of the counterweight 32 rearward of the step 39.

[0027] As shown in Figures 4 and 5, a U-shaped notched groove 41 extending straight forward is formed in the center of the rear end of the counterweight 32 in the Y direction. The front end of the notched groove 41 reaches close to the step 39. A lower pin hole 42 is formed penetrating the right side of the notched groove 41 in the rear part of the upper surface of the counterweight 32. The base end of a substantially cylindrical lower pin 43 is fitted into the lower pin hole 42. The tip side portion of the lower pin 43 protrudes upward. The height of the upper end of the lower pin 43 is the same as the height of the upper end of the step 39.

[0028] As shown in Figures 4 and 6, a support shaft 44 extending in the Z direction is inserted into the notched groove 41 of the counterweight 32. The support shaft 44 is arranged so as not to come into contact with the counterweight 32. The lower end side of the support shaft 44 is fixed to the lower case 21 (see Figure 1). The height of the upper end of the support shaft 44 is the same as the height of the upper end of the step 39. An annular rotating member 45 is rotatably supported on the upper end of the support shaft 44.

[0029] That is, the support shaft 44 supports the rotating member 45 so that the rotating member 45 can rotate in both forward and reverse directions around the support shaft 44 as the center of rotation. The height of the upper surface of the rotating member 45 is the same as the height of the upper end of the step 39. The rotating member 45 is disposed so as not to come into contact with the moving plate 31 and the counterweight 32.

[0030] An upper pin hole 46 is formed through the left rear end of the moving plate 31. The base end of a substantially cylindrical upper pin 47 fits into the upper pin hole 46. The tip side portion of the upper pin 47 protrudes downward. The height of the lower end of the upper pin 47 is the same as the height of the lower surface of the rotating member 45. Two U-shaped cutouts 48 are formed on the periphery of the rotating member 45.

[0031] The two notches 48 are disposed at positions facing each other across the center of the rotating member 45. That is, the two notches 48 are disposed at positions that are 180° out of phase with each other with respect to the center of the rotating member 45. A tip portion of the upper pin 47 is inserted into one of the two notches 48, and a tip portion of the lower pin 43 is inserted into the other. When the moving plate 31 is linearly reciprocated in the X direction, the moving force of the moving plate 31 is transmitted to the counterweight 32 via the upper pin 47, the rotating member 45, and the lower pin 43, and the counterweight 32 is linearly reciprocated in the X direction in the opposite direction to the moving plate 31.

[0032] In this embodiment, as an example, the rotating member 45, the upper pin 47, and the lower pin 43 constitute a transmission mechanism 49 that transmits the moving force of the moving plate 31 when it moves linearly back and forth in the X direction to the counterweight 32, thereby causing the counterweight 32 to move linearly back and forth in the X direction in the opposite direction to the moving plate 31. Note that the transmission mechanism 49 in this embodiment is, as an example, disposed between the moving plate 31 and the counterweight 32 in the Z direction, which is the axial direction of the main shaft 18.

[0033] Next, the operation of the driving tool 11 will be described. When the second bevel gear 23 is rotationally driven by the pressure of compressed air supplied from an air compressor (not shown), the rotational force of the second bevel gear 23 is transmitted to the main shaft 18 via the first bevel gear 22, and the main shaft 18 is rotationally driven about its axis J. Then, the eccentric part 25 moves along a circular orbit centered on the axis J of the main shaft 18. In other words, the eccentric part 25 rotates (revolves) about the axis J of the main shaft 18.

[0034] At this time, imbalance during rotation of the main shaft 18 caused by deviation of the center position of the eccentric part 25 from the axis J of the main shaft 18 is suppressed by the balance weight 30. Therefore, rotation about the axis J of the main shaft 18 is stabilized. Then, when the eccentric part 25 rotates about the axis J of the main shaft 18, the outer ring 29 of the bearing 28 that constitutes the eccentric part 25 rotates while contacting the inner surface of the long hole 35 of the moving plate 31.

[0035] In this case, the eccentric part 25 can contact the inner surface of the long hole 35 in the X direction, but cannot contact it in the Y direction. That is, the eccentric part 25 can apply a pressing force to the inner surface of the long hole 35 in the X direction, but cannot apply a pressing force in the Y direction. Therefore, when the eccentric part 25 rotates around the axis J of the main shaft 18, the eccentric part 25 alternately presses the moving plate 31 forward and backward in the X direction on the inner surface of the long hole 35.

[0036] Then, the movable plate 31 moves reciprocatingly in a straight line in the X direction together with the tip tool support part 14, the tip tool attachment part 16 provided on the tip tool support part 14, and the tip tool 15 attached to the tip tool attachment part 16. That is, the movable body 38 and the tip tool 15 move reciprocatingly in a straight line together in the X direction. This allows the tip tool 15 to perform its function.

[0037] In this case, as shown in Fig. 7, when the movable plate 31 is pushed forward by the eccentric portion 25 and moved forward a predetermined distance, the upper pin 47 also moves forward a predetermined distance equal to the movement of the movable plate 31. This forward movement of the upper pin 47 by a predetermined distance causes the rotating member 45 to rotate by a predetermined angle in the clockwise direction in Fig. 7. This clockwise rotation of the rotating member 45 by a predetermined angle causes the lower pin 43 to move backward a distance equal to the predetermined distance forward of the upper pin 47. When the lower pin 43 is moved backward a predetermined distance, the counterweight 32 also moves backward a predetermined distance equal to the movement of the lower pin 43.

[0038] On the other hand, as shown in Fig. 8, when the movable plate 31 is pushed backward by the eccentric portion 25 and moved backward by a predetermined distance, the upper pin 47 also moves backward by the same predetermined distance as the movement of the movable plate 31. This rearward movement of the upper pin 47 by the predetermined distance rotates the rotating member 45 by a predetermined angle in the counterclockwise direction in Fig. 8. This counterclockwise rotation of the rotating member 45 by the predetermined angle moves the lower pin 43 forward by the same distance as the predetermined distance rearward of the upper pin 47. When the lower pin 43 moves forward by the predetermined distance, the counterweight 32 also moves forward by the same predetermined distance as the movement of the lower pin 43.

[0039] In this way, the movable body 38 to which the tool bit 15 is attached and the counterweight 32 move linearly back and forth in opposite directions in the X direction (front-rear direction). Therefore, the inertial force caused by the linear reciprocating movement of the movable body 38 to which the tool bit 15 is attached is canceled by the counterweight 32. Therefore, vibrations generated by the linear reciprocating movement of the movable body 38 to which the tool bit 15 is attached are reduced.

[0040] According to the embodiment described above in detail, the following effects are achieved. (1) The driving tool 11 includes a main shaft 18 which is rotationally driven about an axis J and which is provided with an eccentric part 25 whose center is located at a position offset from the axis J, a movable body 38 which has an elongated hole 35 into which the eccentric part 25 is inserted and which is moved linearly back and forth in an X direction perpendicular to the axis J as the main shaft 18 rotates while contacting the inner surface of the elongated hole 35, and to which a tool tip 15 can be attached, a counterweight 32 which is arranged so as to be able to move linearly back and forth in the X direction, and a transmission mechanism 49 which transmits the moving force of the movable body 38 when it moves linearly back and forth to the counterweight 32, thereby moving the counterweight 32 linearly back and forth in the X direction in the opposite direction to the movable body 38. The counterweight 32 is arranged on the axis J of the main shaft 18. According to this configuration, the counterweight 32 moves linearly back and forth in the X direction opposite to the moving body 38 due to the moving force generated when the moving body 38 moves linearly back and forth in the X direction perpendicular to the axis J of the main shaft 18. Therefore, the inertial force caused by the linear reciprocating movement of the moving body 38 can be canceled by the counterweight 32, so that the vibration generated by the linear reciprocating movement of the moving body 38 can be reduced. In addition, since the counterweight 32 is disposed on the axis J of the main shaft 18, the size of the main body 12 in the X direction can be reduced compared to the case where the counterweight 32 is disposed next to the main shaft 18 in the X direction. Therefore, it is possible to provide a driving tool 11 that can be made compact while reducing vibration during use.

[0041] (2) In the driving tool 11, the transmission mechanism 49 is disposed between the movable plate 31 (moving body 38) and the counterweight 32 in the Z direction, which is the axial direction of the main shaft 18. According to this configuration, the movable plate 31, the counterweight 32, and the transmission mechanism 49 are disposed in a stacked manner in the Z direction, which is the axial direction of the main shaft 18. This makes it possible to further reduce the size of the main body 12 in the X direction, which in turn contributes to the miniaturization of the driving tool 11.

[0042] (Example of change) The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other as long as they are not technically inconsistent.

[0043] As shown in Figs. 3, 9 and 10, the convex portion 26 of the eccentric portion 25 may be provided with a changeable distance D from the center of the convex portion 26 to the axis J of the main shaft 18 in the radial direction with respect to the lower surface of the main shaft 18. For example, a male screw portion 50 may be formed in the convex portion 26, and a plurality of (four in this example) female screw holes 51 into which the male screw portion 50 of the convex portion 26 can be screwed may be provided on the lower surface of the main shaft 18. In this case, the plurality of female screw holes 51 are arranged so that their distances from the axis J of the main shaft 18 in the radial direction are different from each other. In this way, by changing the female screw hole 51 into which the convex portion 26 of the eccentric portion 25 is screwed, the distance from the center of the convex portion 26 of the eccentric portion 25 to the axis J of the main shaft 18 in the radial direction of the main shaft 18 can be changed. This allows the amplitude (stroke) of the moving body 38 when it moves linearly back and forth to be changed.

[0044] 1 and 11, the tool tip support part 14 of the movable body 38 may include a shock absorbing part 52 that absorbs a shock when a shock is applied to the tool tip 15 from the front in the X direction. In this case, the tool tip support part 14 includes a cylindrical first member 53, a cylindrical second member 56 into which a rear end part 55 having a flange 54 of the first member 53 is slidably inserted, a plurality of annular leaf springs 57 (two in this example) disposed between the flange 54 of the first member 53 and the front end face of the second member 56 as an example of the shock absorbing part 52, and a stopper mechanism 58 provided in the second member 56 to prevent the rear end part 55 of the first member 53 from coming off the second member 56.

[0045] The rear end 55 of the first member 53 is inserted into each leaf spring 57. The outer diameter of the flange 54 is the same as the outer diameter of the second member 56. The stopper mechanism 58 includes a disk-shaped partition wall 60 having a through hole 59 in the center and fixed inside the second member 56, and a substantially cylindrical insertion member 61 having a front end connected to the rear end 55 of the first member 53 by, for example, recess-and-projection fitting while being slidably inserted into the through hole 59. A disk-shaped expanded diameter portion 62 having a diameter larger than the through hole 59 is formed at the rear end of the insertion member 61, and the expanded diameter portion 62 is in contact with the rear surface of the partition wall 60.

[0046] 1 and 11, when an impact is applied to the tool bit 15 from the front in the X direction, the leaf springs 57 elastically deform to contract as shown in Fig. 12, thereby absorbing the impact. At this time, the first member 53 moves rearward together with the insertion member 61, and the enlarged diameter portion 62 of the insertion member 61 moves away from the rear surface of the partition wall 60. In this way, when an impact is applied from the front to the tool bit 15 attached to the movable body 38, the impact can be absorbed by the impact absorbing portion 52, so that the impact can be prevented from being transmitted from the movable body 38 to the spindle 18.

[0047] 13 and 14, the transmission mechanism 49 may be replaced with a transmission mechanism 63. The transmission mechanism 63 is composed of an upper shaft 64 extending in the Y direction provided at the rear of the moving plate 31, a lower shaft 65 extending in the Y direction provided at the rear of the counterweight 32, and a central shaft 67 extending in the Y direction and having a substantially rectangular parallelepiped engagement portion 66 at its center. At both ends in the longitudinal direction of the engagement portion 66, U-shaped notched recesses 68 into which the upper shaft 64 and the lower shaft 65 are inserted are formed. The two notched recesses 68 face each other across the central shaft 67. Both ends of the central shaft 67 are rotatably supported by a pair of guide plates 33 (see FIG. 2). In this way, the moving force of the moving body 38 when it moves back and forth linearly can be transmitted to the counterweight 32 more efficiently than with the transmission mechanism 49.

[0048] The transmission mechanism 49 does not necessarily have to be disposed between the moving plate 31 (moving body 38 ) and the counterweight 32 in the Z direction, which is the axial direction of the main shaft 18 . The upper pin 47 and the lower pin 43 may be configured to be supported at both ends, instead of being supported at one end as in the above embodiment.

[0049] The insertion portion is not limited to the long hole 35, but may be configured as a recess or a notched groove. The bearing 28 may be omitted, and the eccentric portion 25 may be formed only by the protrusion 26. In this case, it is preferable that the outer diameter of the protrusion 26 is made approximately the same as that of the bearing 28.

[0050] The counterweight 32 may be configured so that a weight can be attached detachably. In this way, a weight of a desired weight can be attached to the counterweight 32, so that the weight of the counterweight 32 can be easily adjusted.

[0051] 15 and 16, the tool holder 14 constituting the movable body 38 may include a weight housing 70 as an example of a weight mounting part to which a weight 69 can be detachably attached. In this case, the weight housing 70 is formed by an internal space of the cylindrical tool holder 14 capable of housing a plurality of cylindrical weights 69 (three as an example in FIG. 15). The weight 69 is attached to and detached from the weight housing 70 of the tool holder 14 with the tool holder 16 removed from the tip of the tool holder 14 as shown in FIG. 16. In other words, the weight 69 is attached to and detached from the weight housing 70 by inserting and removing the weight 69 into and from the weight housing 70 through the tip opening of the tool holder 14. In this way, even if the weight of the tool tip 15 changes, the weight balance between the tool tip 15 and the movable body 38 and the counterweight 32 can be easily maintained by simply storing weights (number) of weights 69 in the weight storage section 70 of the tool tip support section 14 in accordance with the weight of the tool tip 15. It is preferable to make the weight of the counterweight 32 heavy in advance.

[0052] The tool attachment part 16 constituting the movable body 38 may include a weight attachment part to which a weight can be detachably attached. In this case, as one example, the weight attachment part may be formed in the tool attachment part 16 as a female threaded hole, and the weight may be formed with a male threaded part that can be screwed into the female threaded hole, so that the weight can be detachably attached to the tool attachment part 16 by screwing the male threaded part of the weight into the female threaded hole of the tool attachment part 16.

[0053] The movable plate 31 constituting the movable body 38 may have a weight attachment portion to which a weight can be detachably attached. In this case, as one example, the weight attachment portion may be formed in the movable plate 31 as a female screw hole, and the weight may be formed with a male screw portion that can screw into the female screw hole, and the male screw portion of the weight may be screwed into the female screw hole of the movable plate 31, so that the weight can be detachably attached to the movable plate 31.

[0054] The second bevel gear 23 may be configured to be rotated by, for example, an electric motor. [Explanation of symbols]

[0055] 11. Power tools 12...Main body 13...Gripping part 14... Tip tool support part 15... Tip tool 16...Tool attachment part 17…Main body case 18...Spindle 19…Upper case 20…Medium case 21…Lower case 22…First bevel gear 23…Second bevel gear 24…Connection 25...Eccentric part 26…Convex part 27…Inner circle 28…Bearing 29…Outer ring 30…Balance weight 31...Moving board 32…Counterweight 33...Guide plate 34...Guide groove 35...long hole 36...Protrusion 37…hole 38...Mobile 39…Step 40...Groove 41...Notched groove 42…Lower pin hole 43…Lower pin 44…Support shaft 45... Rotating member 46…Upper pin hole 47…Upper pin 48…Notch 49,63...Transmission mechanism 50…Male thread 51... Female thread hole 52…Shock absorbing part 53…First member 54…Flange 55...Rear end 56…Second member 57…Leaf spring 58...Stopper mechanism 59…Through hole 60...Bulkhead 61...Passing member 62...Expanded diameter part 64…Upper shaft 65…lower axis 66…Engagement part 67...Central axis 68…Notched recess 69...weight 70... weight storage portion as an example of a weight attachment portion D...Distance J…Axis line

Claims

1. A main shaft is rotated about an axis line as a rotation center and is provided with an eccentric part whose center is located at a position shifted from the axis line; a movable body having an insertion portion into which the eccentric portion is inserted, the eccentric portion being rotated about the axis while contacting the insertion portion as the spindle rotates, whereby the movable body is moved linearly back and forth in a direction perpendicular to the axis, and a tool tip can be attached to the movable body; A counterweight arranged so as to be capable of reciprocating linearly in the perpendicular direction; a transmission mechanism for transmitting a moving force when the movable body moves linearly back and forth to the counterweight, and for causing the counterweight to move linearly back and forth in the perpendicular direction in a direction opposite to that of the movable body, The counterweight is disposed on the axis, The driving tool, wherein the movable body is provided with a weight attachment portion to which a weight can be detachably attached.

2. The driving tool according to claim 1, wherein the transmission mechanism is disposed between the movable body and the counterweight in the axial direction of the main shaft.

3. 3. The driving tool according to claim 1, wherein the eccentric portion is provided so that a distance from a center of the eccentric portion to the axis line in a radial direction of the main shaft is variable.

4. The driving tool according to any one of claims 1 to 3, characterized in that the movable body includes a shock absorbing portion that absorbs a shock when the shock is applied to the tool bit.

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