Hammer droll

Abstract

To provide a hammer drill that can further select rotation modes having different aspects without depending on a mechanical structure and can be still compacted and is excellent in usability.SOLUTION: A hammer drill 1 includes a motor 6, a controller 16, a tool holder 35, an intermediate shaft 36, a rotation converting part 58 and a change plate 43, and can select a hammer drill mode in which rotation of the tool holder 35 and striking operation by a striking part 50 can be performed simultaneously and a rotation-only mode in which only rotation of the tool holder 35 can be performed, by active / non-active switching of the rotation converting part 58 by the change plate 43, When selecting the rotation-only mode, the hammer drill can further select a first rotation mode (clutch mode) and a second rotation mode (drill mode) in which rotation control of the motor 6 by the controller 16 is different from each other.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a hammer drill having selectable operation modes between a hammer drill mode in which rotation and impact are applied to a tool bit, and a rotation-only mode in which only rotation is applied. [Background technology]

[0002] Hammer drills are known that can be operated in either a hammer drill mode, which applies both rotation and impact to a tool bit held in a tool holder, or a rotation-only mode, which applies only rotation. For example, the hammer drill disclosed in Japanese Patent No. 6735118 (Patent Document 1) includes a tool holder that houses a striking part and is movable back and forth and biased to a forward position. This hammer drill also includes an intermediate shaft that transmits rotation from a motor and is disposed parallel to the tool holder. The intermediate shaft includes a gear that transmits rotation to the tool holder and a rotation conversion part (a boss sleeve and a clutch) that converts the rotation of the intermediate shaft into operation of the striking part. This hammer drill can select the drill mode by operating a mode selector lever to restrict the retraction of the tool holder to a position where the clutch does not engage with the boss sleeve. The hammer drill mode can also be selected by operating the mode selector lever to allow the tool holder to retract to a position where the clutch engages with the boss sleeve. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6735118 Summary of the Invention [Problem to be solved by the invention]

[0004] With a hammer drill like that described in Patent Document 1, for example, when attaching a metal fitting to a concrete plug driven into concrete, the worker first drills holes in the concrete in hammer drill mode to form pilot holes, and then drives the concrete plug into the pilot holes.The worker then uses a screwdriver to drive screws into the concrete plug and attach the metal fitting. In this case, the worker must prepare a screwdriver in addition to the hammer drill and switch between them when working, which is troublesome when performing the same work multiple times. On the other hand, if a hammer drill such as that disclosed in Patent Document 1 could also select a clutch mode in which the transmission of rotation to the tool holder is stopped at a predetermined torque, it would be possible to drill pilot holes and fasten screws with a single power tool. However, the mechanism for selecting each operation mode would be complicated, which would increase the number of parts, size, and weight, making it difficult to use.

[0005] Therefore, the present disclosure aims to provide a hammer drill that can maintain compactness and be easy to use by allowing the selection of different rotation modes without relying on a mechanical structure. [Means for solving the problem]

[0006] In order to achieve the above object, the present disclosure provides a hammer drill, A motor; a controller that controls the driving of the motor; a cylindrical tool holder capable of holding a tool bit at its front end, accommodating a striking portion of the tool bit inside, and being rotatable when driven by a motor; a rotation conversion unit that converts the rotation of the motor into a striking motion of the striking unit; a mode switching member capable of switching between an active state and an inactive state of the rotation conversion unit, By switching the state of the rotation conversion unit using the mode switching member, it is possible to select at least between a hammer drill mode in which the tool holder can rotate and the impact unit can perform an impact action simultaneously, and a rotation-only mode in which the tool holder can only rotate. When the rotation only mode is selected, it is possible to further select at least a first rotation mode and a second rotation mode, which are different from each other in the rotation control of the motor by the controller. [Effects of the Invention]

[0007] According to the present disclosure, in the rotation-only mode, at least two rotation modes can be selected by controlling the rotation of the motor without relying on a mechanical structure. This allows for a wider range of rotation modes to be selected depending on the task, improving usability. Furthermore, since multiple rotation modes can be selected electrically, the number of parts does not increase and compactness can be maintained. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a rear perspective view of the hammer drill (hammer drill mode). [Figure 2] FIG. 2 is a central longitudinal cross-sectional view of the hammer drill (hammer drill mode). [Figure 3] FIG. 3 is an enlarged view of the rotating / impacting mechanism portion in FIG. 2. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA in FIG. [Figure 5] FIG. 2 is an exploded perspective view of the mode switching unit as seen from the front. [Figure 6] FIG. 2 is an exploded perspective view of the mode switching unit from the rear. [Figure 7] FIG. 4 is a cross-sectional view taken along line BB in FIG. 3. [Figure 8] FIG. 10 is a rear view of the operating lever portion with the main body housing omitted (hammer drill mode). [Figure 9] FIG. 10 is a rear view of the operating lever portion with the main body housing omitted (rotation only mode). [Figure 10] FIG. 4 is an explanatory view showing a state in which the tool holder in FIG. 3 is retracted. [Figure 11] FIG. 11 is a cross-sectional view taken along line CC in FIG. [Figure 12] FIG. 4 is an enlarged view of the rotation / impact mechanism portion in FIG. 3 in the rotation-only mode. [Figure 13] FIG. 13 is a cross-sectional view taken along line DD in FIG. 12. [Figure 14] 10 is a graph showing the maximum rotation speed and the time required to reach it in a drill mode and a clutch mode, respectively. [Figure 15] FIG. 10 is a perspective view of a screw tightening adapter and a hammer drill according to a reference example. [Figure 16] FIG. 2 is a central vertical cross-sectional view of the screw tightening adapter. [Figure 17] 17A is a cross-sectional view taken along line EE in FIG. 16, and FIG. 17B is a cross-sectional view taken along line FF in FIG. [Figure 18] FIG. 2 is a central vertical cross-sectional view showing a state in which the screw tightening adapter is attached to the hammer drill. DETAILED DESCRIPTION OF THE INVENTION

[0009] In one embodiment of the present disclosure, an intermediate shaft may be provided parallel to the tool holder to transmit the rotation of the motor and to transmit the rotation to the tool holder, and the rotation conversion unit may be provided on the intermediate shaft. According to this configuration, switching between the hammer drill mode and the rotation-only mode can be performed smoothly on the intermediate shaft. In one embodiment of the present disclosure, the first rotation mode may be a clutch function enabled mode in which the rotation of the motor is stopped by a predetermined torque applied to the tool holder, and the second rotation mode may be a clutch function disabled mode. With this configuration, for example, operations such as drilling a pilot hole in a workpiece in hammer drill mode and then fastening a screw in clutch function enabled mode can be performed consecutively using only the hammer drill. In one embodiment of the present disclosure, torque may be adjustable in clutched mode. With this configuration, the clutch function enabled mode can be used with an appropriate torque according to the specific nature of the screw tightening operation. In one embodiment of the present disclosure, the maximum rotation speed of the motor in the clutch function-disabled mode may be set to be higher than that in the clutch function-enabled mode. This configuration makes it easy to drill holes even in hard workpieces such as concrete. In one embodiment of the present disclosure, the time from when the motor is started until it reaches the maximum rotation speed may be set to be longer in the clutch function mode than in the clutch function non-function mode. This configuration makes it less likely for the driver bit to come off the screw, a phenomenon known as cam-out, to occur, and allows for smooth screw tightening.

[0010] In one embodiment of the present disclosure, the device may further include an operating member that switches the mode switching member between a switching state to the hammer drill mode and a switching state to the rotation-only mode, and a position detection sensor that detects the operating position of the operating member. The controller may be capable of selecting between the first rotation mode and the second rotation mode when the position detection sensor detects the operating position of the operating member that has switched the mode switching member to the rotation-only mode. According to this configuration, when the operation member is operated to switch to the rotation-only mode, it becomes possible to automatically select between the first rotation mode and the second rotation mode, making it easy to switch between the rotation modes. In one embodiment of the present disclosure, when either the first rotation mode or the second rotation mode is selected in the rotation-only mode, the controller may store the selected rotation mode, and when the rotation-only mode is then selected again after the hammer drill mode is selected, the controller may automatically switch to the stored first rotation mode or second rotation mode. This configuration saves the trouble of operation when the same work (screw tightening or drilling) is repeatedly performed with use in hammer drill mode in between, resulting in improved usability.

[0011] In one embodiment of the present disclosure, a main body housing may be provided to house the motor, the tool holder, the rotation conversion unit, and the mode switching member, and a grip portion may be formed in a loop shape at the rear of the main body housing. Furthermore, an operating section that can select between a clutch function mode and a clutch function non-mode when the rotation-only mode is selected may be provided on the inner surface of the loop-shaped portion in front of the grip section. According to this configuration, the operation unit can be disposed in a location that is easy to operate and unlikely to be operated by mistake. In one embodiment of the present disclosure, the grip portion houses a switch for driving the motor, the switch having a trigger that protrudes forward, and the operating member may be located on the inner surface of the loop-shaped portion in front of the trigger. According to this configuration, the operating member can be disposed in a location that is easy to operate and unlikely to be operated by mistake. In one embodiment of the present disclosure, the rotation of the motor may be switchable between forward and reverse directions. With this configuration, in the clutch function enabled mode, the device can be used to loosen screws in addition to tightening screws. In one embodiment of the present disclosure, the rotation of the motor may be switchable between forward and reverse, and when the rotation of the motor is switched to reverse rotation, the clutch function enabled mode may be disabled. With this configuration, when the motor is rotated in the reverse direction to loosen a screw, the clutch function is activated and the screw is not prevented from being loosened. [Example]

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Fig. 1 is a rear perspective view showing an example of a hammer drill. Fig. 2 is a central longitudinal cross-sectional view of the hammer drill. Fig. 3 is an enlarged view of the rotation / impact mechanism portion in Fig. 2. Fig. 4 is a cross-sectional view taken along line AA in Fig. 3. All of these are in hammer drill mode. The hammer drill 1 has housings that form the outer shell, which are a main housing 2 and a front housing 3. The main housing 2 is formed by screwing together left and right half housings 2a and 2b. The front housing 3 is connected to the upper front part of the main housing 2. The main body housing 2 houses a motor housing 4 in its lower front section. The main body housing 2 houses an inner housing 5 spanning its upper front section and the front housing 3. A motor 6 is held within the motor housing 4 with its rotating shaft 7 facing upward. The inner housing 5 is fastened to the motor housing 4 with screws. The front housing 3 has a rear tubular portion 8 and a front tubular portion 9. The rear tubular portion 8 is screwed to the inner housing 5. The rear tubular portion 8 expands toward the rear and is joined to the upper front portion of the main housing 2 while being screwed to the inner housing 5. The front tubular portion 9 is integrally formed on the front side of the rear tubular portion 8. A side handle (not shown) can be attached to the base of the front tubular portion 9. A rotation / impact mechanism portion 10 is housed within the inner housing 5 and the front housing 3.

[0013] A grip portion 11 is formed in the vertical direction at the rear of the main body housing 2. The grip portion 11 is loop-shaped and connected to the main body housing 2 at its upper and lower ends. A switch 12 is housed in the upper part of the grip portion 11. The switch 12 is equipped with a trigger 13 that protrudes forward. A forward / reverse switch button 14 for switching the rotation of the motor 6 is provided above the trigger 13. A battery pack 15, which serves as a power source, is detachably attached to the lower rear part of the main body housing 2 below the grip portion 11. A controller 16 is housed between the motor 6 and the battery pack 15. The controller 16 includes a control circuit board 17. Well-known elements such as a CPU, RAM, and ROM are mounted on the control circuit board 17, and a motor control circuit and a power supply circuit are formed on the board. An operation panel 18 is provided on the front inner peripheral surface of the loop-shaped portion above the controller 16. Three buttons 19A to 19C are provided on the operation panel 18. The upper button 19A corresponds to the hammer drill mode, the lower left button 19B corresponds to the drill mode, and the lower right button 19C corresponds to the clutch mode. The operation panel 18 is an example of an operation unit of the present disclosure.

[0014] As shown in Figures 5 and 6, the inner housing 5 has an elliptical shape in a front view that is open at the front and extends in the vertical direction. The inner housing 5 has an upper plate portion 20, a middle tubular portion 21, and a lower tubular portion 22. The upper plate portion 20 is a rectangular dish-like portion in a plan view that extends in the front-to-rear direction at the top of the inner housing 5. Support pins 23, 23 that protrude outward to the left and right are formed on the left and right rear sides of the upper plate portion 20. A rubber ring 24 is attached to each support pin 23. As shown in Figure 7, each rubber ring 24 is held by a boss 25 that protrudes toward the center from the inner surface of the left and right half housings 2a, 2b. Therefore, the upper part of the inner housing 5 is elastically held to the main housing 2 via the rubber rings 24, 24. The middle cylinder portion 21 extends in the front-rear direction below the upper plate portion 20. As shown in Figure 4, protruding portions 26, 26 are formed on the left and right sides of the middle cylinder portion 21, protruding outward to the left and right and extending forward. A guide recess 27 is formed within each protruding portion 26, with its front end opening. The rear portion of the middle cylinder portion 21 forms a small-diameter portion 28 whose outer diameter is smaller than that of the front portion.

[0015] An inner support 30 is screwed to the front side of the middle cylindrical portion 21 from the front. The inner support 30 is a short cylinder having a central hole 31 that is coaxial with the middle cylindrical portion 21. The central hole 31 has a two-stage diameter, with the front portion having a larger diameter than the rear portion. A metal bearing 32 is press-fitted and held in the front portion of the central hole 31. Guide grooves 33, 33 that penetrate in the front-rear direction outside the metal bearing 32 are formed on the left and right inner surfaces of the central hole 31. The guide grooves 33, 33 are continuous with guide recesses 27, 27 provided in the middle cylindrical portion 21. The lower cylindrical portion 22 is a bottomed cylindrical portion that opens forward below the middle cylindrical portion 21. The upper end of the rotating shaft 7 of the motor 6 passes through the upper part of the motor housing 4 and the lower part of the inner housing 5. A first gear 34 is provided at the upper end of the rotating shaft 7, protruding into the inner housing 5 below the lower cylindrical portion 22.

[0016] The rotating / impacting mechanism 10 includes a tool holder 35 and an intermediate shaft 36 . The tool holder 35 is held by a metal bearing 32 of the inner support 30 and a bearing 37 held in the front cylindrical portion 9 of the front housing 3. The tool holder 35 is rotatable and movable back and forth with its axis, which is the striking axis L, oriented in the front-to-rear direction. The front end of the tool holder 35 protrudes forward from the front cylindrical portion 9. An operating sleeve 38 for attaching and detaching a bit B is provided at the front end of the tool holder 35. The bit B is an example of an end tool of the present disclosure. A fourth gear 40 is mounted on the outer periphery of the rear portion of the tool holder 35 so as to be rotatable integrally with the tool holder 35. A stopper ring 41 is fixed between the fourth gear 40 and the bearing 37 on the outer periphery of the tool holder 35. The forward movement of the tool holder 35 is restricted at the position shown in FIGS. 2 to 4 where the stopper ring 41 abuts against the inner ring of the bearing 37. A washer 42 and a change plate 43 are mounted on the outer periphery of the tool holder 35 between the fourth gear 40 and the metal bearing 32. As shown in FIGS. 5 and 6 , the change plate 43 is a ring-shaped plate with outward-facing receiving portions 44, 44 formed on both the left and right sides. A semicircular locking portion 45 that widens downward is formed on the lower part of the change plate 43. The backward movement of the tool holder 35 is restricted at the position where the change plate 43 abuts against the metal bearing 32. The change plate 43 is an example of a mode switching member of the present disclosure.

[0017] A striking unit 50 is provided inside the tool holder 35. The striking unit 50 includes a piston cylinder 51, a striker 52, and an impact bolt 53. The piston cylinder 51 is cylindrical and open at the front, and is housed from the rear side of the tool holder 35 so as to be movable back and forth on the striking axis L. The striker 52 is housed in the piston cylinder 51 via an air chamber 54 so as to be movable back and forth on the striking axis L. The impact bolt 53 is accommodated in front of the striker 52 so as to be movable back and forth on the impact axis L. The impact bolt 53 is capable of abutting against the rear end of the bit B inserted into the front end of the tool holder 35.

[0018] The intermediate shaft 36 is disposed below the tool holder 35 and parallel to the striking axis L. The front end of the intermediate shaft 36 is supported by a front bearing 55 provided in the rear cylindrical portion 8 of the front housing 3. The rear end of the intermediate shaft 36 is supported by a rear bearing 56 provided in the lower cylindrical portion 22 of the inner housing 5. A second gear 57 is fixed to the rear portion of the intermediate shaft 36, forward of the rear bearing 56. The second gear 57 is engaged with the first gear 34 provided on the rotating shaft 7. Therefore, the intermediate shaft 36 rotates at a reduced speed via the first gear 34 and the second gear 57, due to the rotation of the rotating shaft 7 caused by the drive of the motor 6. A rotation conversion portion 58 is provided on the intermediate shaft 36 in front of the second gear 57. The rotation conversion portion 58 includes a boss sleeve 59, a swash bearing 60, a rod 61, and a clutch gear 62. The boss sleeve 59 is rotatably mounted on the intermediate shaft 36 between a stopper 63 provided in the middle of the intermediate shaft 36 and the second gear 57. A boss-side engagement portion 64 is provided on the front surface of the boss sleeve 59. The swash bearing 60 is provided on the outer periphery of the boss sleeve 59 and is tilted relative to the axis of the boss sleeve 59. The rod 61 protrudes radially upward from the outer ring of the swash bearing 60. The tip of the rod 61 is connected to the rear end of the piston cylinder 51 via a connecting pin 65.

[0019] The clutch gear 62 is mounted on a spline portion 66 formed on the intermediate shaft 36 in front of the stopper 63. The clutch gear 62 is coupled to the intermediate shaft 36 so as to be rotatable integrally with the intermediate shaft 36 and slidable in the axial direction. A gear-side engaging portion 67 protrudes rearward from the rear surface of the clutch gear 62. The gear-side engaging portion 67 engages with the boss-side engaging portion 64 of the boss sleeve 59 in the rotational direction when the clutch gear 62 is in the retracted position. A third gear 68 is formed on the front portion of the clutch gear 62. The third gear 68 meshes with the fourth gear 40 provided on the tool holder 35. A locking groove 69 is formed in the circumferential direction in the middle portion of the third gear 68. The locking portion 45 of the change plate 43 locks into the locking groove 69 from above. Therefore, the clutch gear 62 moves forward and backward following the forward and backward movement of the change plate 43. When the change plate 43 is in the forward position, the clutch gear 62 moves to a front position where the gear-side engaging portion 67 is separated from the boss-side engaging portion 64. When the change plate 43 is in the backward position, the clutch gear 62 moves to a rear position where the gear-side engaging portion 67 engages with the boss-side engaging portion 64.

[0020] A mode switching unit 70 is provided in the center cylindrical portion 21 of the inner housing 5 behind the tool holder 35. The mode switching unit 70 includes a regulating plate 71, a cam mechanism 72, an operating lever 73, and a mode detection switch 74. The regulating plate 71 has a base end portion 75 and a pair of regulating portions 76, 76. The base end portion 75 is a circular plate when viewed from the front, and has a through hole 77 formed in the center thereof, which is concentric with the striking axis L. A rubber plate 78 is provided coaxially on the front surface of the base end portion 75. The rubber plate 78 is integrally molded with the base end portion 75 of the iron regulating plate 71. The rubber plate 78 is a ring plate with a slightly smaller diameter than the base end portion 75, and its center hole has a larger diameter than the through hole 77 of the base end portion 75. A pair of stoppers 79, 79 that protrude forward are provided on the left and right sides of the front surface of the rubber plate 78.

[0021] The restricting portions 76, 76 are strip-shaped plates that extend outward from the left and right sides of the base end portion 75 and then extend forward in parallel. The restricting portions 76, 76 are symmetrically arranged so that one restricting portion is located in each of the left and right regions facing each other with respect to the impact axis L. The restricting portions 76, 76 fit into the left and right guide recesses 27, 27 of the middle cylinder portion 21 and extend forward. Front portions of the restricting portions 76, 76 pass through the left and right guide grooves 33, 33 of the inner support 30, respectively. Therefore, the restricting plate 71 is held movable back and forth in the direction of the impact axis L while its rotation is restricted within the middle cylinder portion 21 and the inner support 30. The receiving portions 44, 44 of the change plate 43 are located in front of the restricting portions 76, 76 that pass through the guide grooves 33, 33 of the inner support 30.

[0022] The cam mechanism 72 includes a front cam 80, a rear cam 81, and a conical spring 82, each of which is concentric with the impact axis L. The front cam 80 is disk-shaped and has approximately the same diameter as the base end 75 of the regulating plate 71, with a through-hole 83 formed in its center. Four front cam claws 84, 84... are provided on the rear surface of the front cam 80, projecting rearward on the top, bottom, left, and right. A pair of engagement pieces 85, 85 that protrude outward to the left and right are formed on the left and right sides of the front cam 80. The engagement pieces 85, 85 engage with the left and right guide recesses 27, 27 of the middle cylindrical portion 21. Therefore, the front cam 80 is held by the guide recesses 27, 27 so as to be able to move back and forth in the direction of the impact axis L while its rotation is restricted within the middle cylindrical portion 21.

[0023] The rear cam 81 is rotatably housed within the middle cylinder portion 21 behind the front cam 80. The rear cam 81 is disk-shaped and has the same diameter as the front cam 80, and a front shaft portion 86 that protrudes forward is formed in its center. The front shaft portion 86 passes through the through-hole 83 of the front cam 80 and the through-hole 77 of the base end portion 75 of the regulating plate 71. Four rear cam claws 87, 87... are circumferentially equally spaced and protrude forward from the front surface of the rear cam 81 around the front shaft portion 86. A receiving washer 88 that abuts against the front surface of the front shaft portion 86 is provided on the front surface of the base end portion 75 through which the front shaft portion 86 passes within the center hole of the rubber plate 78. The receiving washer 88 has a larger diameter than the front shaft portion 86 and is fixed perpendicular to the front shaft portion 86 by a flat head screw 89 that passes through the receiving washer 88 from the front and is screwed into the front shaft portion 86. The receiving washer 88 prevents the base end portion 75 and the front cam 80 from coming off forward from the front shaft portion 86.

[0024] A rear shaft portion 90, which is inserted into the small diameter portion 28 of the central cylindrical portion 21, is formed coaxially on the rear surface of the rear cam 81. An O-ring 91 is fitted to the rear shaft portion 90 to seal the gap between it and the small diameter portion 28. A fitting groove 92 extending in the diameter direction is formed on the rear surface of the rear shaft portion 90. In rear view, the fitting groove 92 is located between the rear cam claws 87, 87 that are adjacent in the circumferential direction. A threaded hole 93 extending forward is formed within the fitting groove 92. With the fitting groove 92 oriented in the up-down direction, the threaded hole 93 is located at a position slightly eccentric to the downward direction of the impact axis L as shown in FIG. 7. Two locking recesses 94A, 94B are formed radially on the rear surface of the rear cam 81, radially outward of the rear shaft portion 90. One of the locking recesses 94A is formed in the same phase as the diameter of the fitting groove 92 in rear view. The other locking recess 94B is located to the circumferential left of the locking recess 94A in rear view. The locking recess 94B is located rearward of the rear cam claw 87.

[0025] The conical spring 82 is mounted on the front shaft portion 86 between the front cam 80 and the rear cam 81. The conical spring 82 is a tapered coil spring whose diameter decreases as it extends forward. The conical spring 82 is located inside each of the front cam claws 84 of the front cam 80 and each of the rear cam claws 87 of the rear cam 81, and urges the front cam 80 forward. Therefore, the regulating plate 71, which the front cam 80 abuts, is also urged forward together with the front cam 80. The advanced regulating plate 71 abuts the front ends of the left and right regulating portions 76, 76 against the receiving portions 44, 44 of the change plate 43. Therefore, the tool holder 35 is urged to the advanced position shown in FIGS. 3 and 4 , where the stopper ring 41 abuts against the bearing 37. At this time, the front cam 80 is pressed against the base end 75 by the force of the conical spring 82 at a position where the rear ends of the front cam claws 84 are slightly forward of the front ends of the rear cam claws 87 of the rear cam 81.

[0026] The operating lever 73 includes a disk portion 100 and a lever portion 101. The disk portion 100 has an outer diameter larger than the outer diameter of the small diameter portion 28 of the middle cylinder portion 21. A front portion 102 of the disk portion 100 has the same diameter as the rear shaft portion 90 of the rear cam 81 and is fitted into the small diameter portion 28 from the rear. Two protrusions 103, 103 are formed in the diameter direction on the front surface of the front portion 102. The protrusions 103, 103 are fitted into fitting grooves 92 of the rear cam 81. The disk portion 100 is connected to the rear cam 81 by threading a screw 104 that passes through the center from the front into a screw hole 93 of the rear cam 81. A notch 105 is formed on the outer periphery of the disk portion 100, diametrically above where the protrusions 103, 103 extend in rear view. At the left end of the notch 105, a pressing portion 106 having a curved peripheral surface is formed. Lever portion 101 protrudes radially outward from disc portion 100. The protruding direction of lever portion 101 is the radially downward direction from which protrusions 103, 103 extend on the opposite side from notch 105. A notch 107 that allows protrusion of lever portion 101 is formed on the lower left side of small diameter portion 28. Operating lever 73 is an example of an operating member of the present disclosure.

[0027] 8 shows the first operating position of the operating lever 73 in which the lever portion 101 protrudes directly downward as viewed from behind. In this first operating position, the rear cam 81 is in a first rotational position in which the rear cam claws 87 are alternately shifted in the circumferential direction relative to the front cam claws 84 of the front cam 80. Therefore, the front cam 80 and the regulating plate 71 are in the first switching state in which they are allowed to move rearward. Therefore, the tool holder 35, together with the change plate 43, is also allowed to move backward. 9 shows the second operating position of the operating lever 73 in which the lever portion 101 protrudes to the lower left when viewed from behind. In this second operating position, the rear cam 81 is in a second rotational position in which the rear cam claws 87 are positioned vertically and horizontally. Therefore, the rear cam claws 87 are in the same phase as the front cam claws 84 of the front cam 80 and are positioned immediately behind the front cam claws 84. As a result, the front cam 80 and the regulating plate 71 enter a second switching state in which rearward movement is restricted. Accordingly, the receiving portions 44, 44 of the change plate 43 come into contact with the regulating portions 76, 76 of the regulating plate 71, and therefore the tool holder 35 is also restricted from moving backward.

[0028] As shown in FIG. 3, a bottomed hole 110 that opens forward is formed on the upper side of the small diameter portion 28. A coil spring 111 and a ball 112 that is urged forward by the coil spring 111 are housed inside the bottomed hole 110. When the rear cam 81 is in the first rotation position, the ball 112 is engaged with the locking recess 94A located in the front. When the rear cam 81 is in the second rotation position, the ball 112 is engaged with the locking recess 94B located in the front. Therefore, a click action occurs when the operating lever 73 is switched between the first and second operating positions. A cover portion 113 is provided above the operation panel 18 on the front inner peripheral surface of the loop-shaped portion of the main housing 2. The cover portion 113 covers almost the entire disk portion 100 of the operation lever 73, and allows the lower portion of the disk portion 100 and the lever portion 101 to protrude from an opening 114 provided at the bottom.

[0029] The mode detection switch 74 is screwed to the rear surface of the top plate 20 of the inner housing 5 above the disk portion 100 of the operating lever 73. The mode detection switch 74 is a microswitch that turns ON when a protruding plunger 115 is pressed by a lever plate 116. The mode detection switch 74 is attached to the rear surface of the top plate 20 with the lever plate 116 facing downward and the plunger 115 to the right. In this state, the lever plate 116 is positioned above the disk portion 100. The mode detection switch 74 is an example of a position detection sensor disclosed herein. In the first operating position of the operating lever 73 shown in Fig. 8, the notch 105 faces upward, and the lever plate 116 is positioned within the notch 105. Therefore, the lever plate 116 and plunger 115 are not pushed in, and the mode detection switch 74 is not turned on. On the other hand, in the second operating position of the operating lever 73 shown in Fig. 9, the pressing part 106, which has rotated to the right in rear view, comes into contact with the lever plate 116 and pushes it upward. Therefore, the plunger 115 is pushed into the lever plate 116, and the mode detection switch 74 is turned on.

[0030] In the hammer drill 1 configured as described above, the lever portion 101 of the operating lever 73 is grasped and operated to the first operating position shown in Fig. 8. This causes the rear cam 81 to move to the first rotation position, and the hammer drill mode is entered, in which a rotation / impact action is obtained as the tool holder 35 moves backward. First, when the operator presses the bit B attached to the front end of the tool holder 35 against the workpiece, a pushing force is applied to the tool holder 35. In the first operating position, as described above, the front cam 80 and the regulating plate 71 are in the first switching state and are allowed to move rearward. Therefore, as shown in FIGS. 10 and 11 , the tool holder 35, together with the regulating plate 71 and the front cam 80, moves back to the retracted position via the change plate 43 against the bias of the conical spring 82. Then, the change plate 43, which moves back together with the tool holder 35, retracts the clutch gear 62. When the tool holder 35 is in the retracted position, the clutch gear 62 engages the gear-side engaging portion 67 with the boss-side engaging portion 64 of the boss sleeve 59 while maintaining the meshing state between the third gear 68 and the fourth gear 40.

[0031] In this state, when the trigger 13 is pressed to turn on the switch 12, the controller 16 illuminates the hammer drill mode button 19A and drives the motor 6. This rotates the rotary shaft 7, causing the first gear 34 to rotate with the rotary shaft 7 and the intermediate shaft 36 to rotate at a reduced speed via the second gear 57. Therefore, the boss sleeve 59 of the rotation conversion unit 58, which is engaged with the clutch gear 62 and activated, rotates with the intermediate shaft 36. When the boss sleeve 59 rotates, the rod 61 swings back and forth via the swash bearing 60, causing the piston cylinder 51 of the striking unit 50 to move back and forth along the striking axis L. This causes the striker 52 to reciprocate along the striking axis L via the air chamber 54, indirectly striking the bit B via the impact bolt 53. At the same time, the rotation of the third gear 68 of the clutch gear 62 is transmitted to the tool holder 35 via the fourth gear 40. This causes the tool holder 35 to rotate, thereby rotating the bit B.

[0032] Next, the lever portion 101 of the operating lever 73 is grasped and operated to the second operating position shown in FIG. 9. This places the rear cam 81 in a second rotation position, as shown in FIGS. 12 and 13. The regulating plate 71 is also in a second switching state, in which its retraction is restricted by the front cam 80 abutting against the rear cam 81. Therefore, the rearward movement of the tool holder 35 is restricted by the abutment of the change plate 43 against the restricting portions 76, 76. Therefore, even if the bit B attached to the front end of the tool holder 35 is pressed against the workpiece, the tool holder 35 does not retract, and neither does the clutch gear 62. Therefore, the rotation conversion unit 58 is inactive. When the motor 6 is driven to rotate the intermediate shaft 36, the rotation from the clutch gear 62 is transmitted to the tool holder 35, resulting in a rotation-only mode. In this rotation-only mode, the pressing portion 106 of the disk portion 100 of the operating lever 73 presses the lever plate 116 of the mode detection switch 74 to turn on the mode detection switch 74. Then, the controller 16 lights up the drill mode button 19B and the clutch mode button 19C on the operation panel 18.

[0033] Here, the operator selects the drill mode and presses button 19B. This causes the controller 16 to switch to the drill mode, which drives the motor 6 so that the rotary shaft 7 rotates at a predetermined speed. This allows the bit B attached to the tool holder 35 to rotate, enabling drilling. Meanwhile, the operator selects the clutch mode and presses button 19C. The controller 16 then drives the motor 6 so that the rotary shaft 7 rotates at a slower speed than in drill mode, transitioning to clutch mode. Clutch mode is an electronic clutch that stops the motor 6 when the current to the motor 6 reaches a preset value, i.e., a torque setting. Therefore, if a bit B with a driver bit attached to the tip is attached to the tool holder 35 and a screw is tightened, the tightening of the screw will finish at the torque setting, which increases as the screw tightening progresses. Furthermore, by operating the forward / reverse switch button 14 to reverse the rotation of the tool holder 35, a tightened screw can also be loosened. The clutch mode is an example of a clutch function-enabled mode of the first rotation mode of the present disclosure, and the drill mode is an example of a clutch function-disabled mode of the second rotation mode of the present disclosure.

[0034] Figure 14 shows the change in the rotation speed of the motor 6 in drill mode and clutch mode. In the initial setting, the maximum rotation speed rd in drill mode is higher than the maximum rotation speed rc in clutch mode. Furthermore, the time td in drill mode from when the motor 6 starts to when it reaches the maximum rotation speed is shorter than the time tc in clutch mode. Furthermore, after selecting the clutch mode, the torque setting value can be adjusted in stages by pressing the illuminated button 19C multiple times. For example, each time button 19C is pressed, the torque setting value T increases in a predetermined order of T1, T2, T3, and T4. Pressing button 19C again from the highest setting T4 returns the torque setting value T to the lowest setting T1. The number of stages of the torque setting value T may be greater or less than this. The operation panel 18 may be provided with a display unit that displays the number of stages using numbers or a scale.

[0035] On the other hand, when drill mode or clutch mode is selected in rotation-only mode, the selected drill mode or clutch mode is stored in the controller 16. If the hammer drill mode is subsequently selected and then the rotation-only mode is selected again, the controller 16 automatically selects the stored drill mode or clutch mode and lights up the corresponding button 19B or button 19C. This eliminates the need to press button 19B or button 19C each time the same task (screw tightening or drilling) is repeatedly performed with a break in the hammer drill mode.

[0036] In both the drill mode and the clutch mode, when the bit B is pressed against the workpiece, a backward pushing force is applied to the tool holder 35. Therefore, a pushing force is also applied to the regulating plate 71, which regulates the backward movement of the tool holder 35 via the change plate 43. However, as shown in Figure 13, the restricting portions 76, 76 of the restricting plate 71 are arranged symmetrically about the striking axis L, and equally support the left and right receiving portions 44 of the change plate 43. Therefore, even if the pushing force increases, the restricting plate 71 will not deform or tilt. This stabilizes the retracted positions of the change plate 43 and tool holder 35, and ultimately stabilizes the advanced position of the clutch gear 62. Therefore, the boss sleeve 59 does not engage with the clutch gear 62 in either the drill mode or the clutch mode, and the inactive state of the rotation converting portion 58 is maintained.

[0037] On the other hand, in both the drill mode and the clutch mode, friction occurs between the inactive boss sleeve 59 and the rotating intermediate shaft 36. This friction may cause the boss sleeve 59 to rotate following the rotation, causing the rod 61 to swing. However, a rubber plate 78 is provided on the front surface of the base end 75 of the restricting plate 71. Therefore, when the rod 61 swings rearward and the piston cylinder 51 retracts, the rear end of the piston cylinder 51 abuts against the left and right stoppers 79, 79 of the rubber plate 78, preventing the piston cylinder 51 from retracting any further. Therefore, rotation of the boss sleeve 59 is restricted via the rod 61, preventing unexpected impact action.

[0038] Thus, the hammer drill 1 of the above-described form includes a motor 6, a controller 16, a tool holder 35, a rotation conversion unit 58, and a change plate 43, and by switching the rotation conversion unit 58 between active and inactive states by the change plate 43, it is possible to select between a hammer drill mode in which the tool holder 35 can rotate and the impact unit 50 can perform an impact operation simultaneously, and a rotation-only mode in which the tool holder 35 can only rotate. When the rotation only mode is selected, a first rotation mode (clutch mode) and a second rotation mode (drill mode) in which the rotation control of the motor 6 by the controller 16 is different from each other can be further selected. With this configuration, in the rotation-only mode, two rotation modes can be selected by controlling the rotation of the motor 6 without relying on a mechanical structure. This allows for a wider range of rotation modes to be selected depending on the task, improving usability. Furthermore, because the two rotation modes can be selected electrically, the number of parts does not increase and compactness can be maintained.

[0039] The intermediate shaft 36 is provided in parallel with the tool holder 35 to which the rotation of the motor 6 is transmitted and which transmits the rotation to the tool holder 35 , and the rotation conversion unit 58 is provided on the intermediate shaft 36 . Therefore, switching between the hammer drill mode and the rotation only mode can be performed smoothly on the intermediate shaft 36. The first rotation mode is a clutch mode in which the rotation of the motor 6 is stopped by a predetermined torque applied to the tool holder 35, and the second rotation mode is a drill mode without a clutch function. Therefore, for example, operations such as drilling a pilot hole in a workpiece in hammer drill mode and then fastening a screw in clutch mode can be performed continuously using only the hammer drill 1. In clutch mode, torque can be adjusted. Therefore, the clutch mode can be used with an appropriate torque according to the specific nature of the screw tightening operation. In the drill mode, the maximum rotation speed of the motor 6 is set higher than in the clutch mode. Therefore, drilling can be easily performed even in hard workpieces such as concrete. The time from when the motor 6 is started until it reaches the maximum rotation speed is set to be longer in the clutch mode than in the drill mode. This reduces the risk of the driver bit coming out of the screw, which is known as cam-out, and allows for smooth screw tightening.

[0040] The machine further includes an operating lever 73 for switching the change plate 43 between a switching state to the hammer drill mode and a switching state to the rotation-only mode, and a mode detection switch 74 for detecting the operating position of the operating lever 73. When the mode detection switch 74 detects the operation position of the operating lever 73 that has switched the change plate 43 to the rotation-only mode, the controller 16 makes it possible to select between the clutch mode and the drill mode. Therefore, when the operating lever 73 is operated to switch to the rotation-only mode, the clutch mode and the drill mode can be selected automatically, making it easy to switch between the rotation modes. When either the clutch mode or the drill mode is selected in the rotation only mode, the controller 16 stores the selected rotation mode, and when the rotation only mode is then selected again after the hammer drill mode is selected, the controller 16 automatically switches to the stored clutch mode or drill mode. Therefore, when the same operation (screw tightening or drilling) is repeatedly performed with an intermission of use in hammer drill mode, the time and effort required for operation is reduced, resulting in improved usability.

[0041] The tool has a main body housing 2 that houses the motor 6, the tool holder 35, the rotation conversion unit 58, and the change plate 43, and a grip unit 11 formed in a loop shape at the rear of the main body housing 2. An operation panel 18 that can be operated to select between clutch mode and drill mode when rotation-only mode is selected is provided on the inner circumferential surface of the loop-shaped portion in front of the grip portion 11. Therefore, the operation panel 18 can be placed in a location that is easy to operate and unlikely to be operated by mistake. The grip portion 11 houses a switch 12 for driving the motor 6, and the switch 12 has a trigger 13 that protrudes forward, and the operating lever 73 is arranged on the inner surface of the loop-shaped portion in front of the trigger 13. Therefore, the operating lever 73 can be disposed in a location that is easy to operate and unlikely to be operated by mistake. The rotation of the motor 6 can be switched between forward and reverse directions. Therefore, in the clutch mode, it can be used to loosen screws in addition to tightening screws.

[0042] Modifications of the present disclosure will be described below. The first rotation mode is not limited to one clutch mode, but may further include a selection from multiple clutch modes with different maximum motor rotation speeds or torque setting values.Similarly, the second rotation mode is not limited to one drill mode, but may further include a selection from multiple drill modes with different maximum motor rotation speeds. In the above embodiment, torque adjustment is possible in the clutch mode, but torque adjustment does not have to be possible. In the above embodiment, the maximum motor rotation speed is set higher in the drill mode than in the clutch mode, but the maximum rotation speed may be the same in both modes. The time it takes to reach the maximum rotation speed from motor startup may also be the same in both modes. The maximum rotation speed may be changeable in both modes. In the clutch mode, the torque setting value may also be automatically changed in response to changes in the maximum rotation speed. The operating member is not limited to the operating lever of the above embodiment. The operating member may be, for example, a dial type, or may be operated by sliding rather than rotating. The operating member may also be located on the side or top of the main body housing. The position detection sensor is not limited to the microswitch in the above embodiment, but may be a non-contact type such as a photoelectric sensor. In the above embodiment, when switching back to rotation-only mode after selecting hammer drill mode, the stored mode is automatically selected, but this automatic selection does not have to be performed, or it may be possible to set whether or not automatic selection is performed on the operation panel. The grip portion is not limited to a loop shape.

[0043] When the rotation of the motor is switched to reverse rotation, the controller may change the rotation speed between the clutch function enabled mode and the clutch function disabled mode. In addition, when the rotation of the motor is switched to reverse rotation, the controller may automatically switch to the clutch function non-operation mode, or the clutch function operation mode and the clutch function non-operation mode may be selectable by operating the operation unit. By disabling the clutch function during reverse rotation in this way, the clutch function will not operate when loosening a screw, preventing the screw from being loosened.

[0044] In a hammer drill, as disclosed in Patent Document 1, for example, a hammer mode may also be selected by switching a gear (third gear 68 in the above embodiment) between a position where it is connected to the intermediate shaft and a position where it is not connected. The mode switching unit is not limited to the use of the regulating plate and cam mechanism unit in the above embodiment. For example, the regulating plate and cam mechanism unit may be eliminated, and the front and rear positions of the change plate may be switched by rotating an operating member provided on the side of the main body housing. The hammer drill is not limited to one in which the tool holder moves back and forth to select the operation mode. The motor is not limited to one with an upward rotation shaft, and may be one with an inclined rotation shaft. The controller may be located in another location. For example, the controller may be located on the top of the battery pack or in the grip. The controller may be located in a location other than the main body housing. The operation unit may also be located on the side or top of the main body housing. The rotation conversion unit is not limited to the above embodiment in which a boss sleeve is provided on an intermediate shaft to swing the rod. The rotation conversion unit may be configured to include, for example, a crankshaft that is rotated by a motor and a connecting rod that connects an eccentric pin provided on the crankshaft to the piston, without using an intermediate shaft. The hammer drill may be an AC machine that is not powered by a battery pack.

[0045] Next, an example will be described as a reference example in which a hammer drill in which the clutch mode is not electrically selectable as in the present disclosure can also perform screw tightening. As shown in Figure 15, a screw tightening adapter (hereinafter simply referred to as "adapter") 200 is attached to a hammer drill 1A. As shown in Figure 18, the hammer drill 1A has the same basic configuration as the hammer drill 1 in Figure 1, and therefore the same components as in Figure 1 are given the same reference numerals and their explanations are omitted. However, the hammer drill 1A does not have a mode switching unit like the above-mentioned embodiment. Here, two coil springs 120, 120 are interposed between the inner support 30 and the change plate 43, and together with the change plate 43, urge the tool holder 35 to the forward position. A ring groove 121 for mounting an adapter 200 is formed on the outer circumferential surface of the front cylindrical portion 9 of the front housing 3. Behind the ring groove 121, four mounting protrusions 122, 122... are formed at equal intervals in the circumferential direction on the outer periphery of the base of the front cylindrical portion 9.

[0046] The operating lever 73 is rotatably mounted on the left side surface of the front housing 3. The operating lever 73 has an eccentric pin 123 that protrudes into the front housing 3. The eccentric pin 123 is located rearward of the change plate 43 and can be moved forward or backward by rotating the operating lever 73. When the eccentric pin 123 is in its front position, the tool holder 35 is in its forward position and the change plate 43 is restricted from moving backward. At this time, the clutch gear 62 moves forward away from the boss sleeve 59, thereby entering a drill mode in which the tool holder 35 is rotated via the third gear 68 and the fourth gear 40. When the eccentric pin 123 is in its rear position, the tool holder 35 and the change plate 43 are allowed to move backward from their forward positions. Therefore, when the change plate 43 moves backward together with the tool holder 35, the clutch gear 62, which has moved backward together with the change plate 43, engages with the boss sleeve 59, entering a hammer drill mode.

[0047] As shown in FIG. 16, the adapter 200 includes an attachment portion 201 and an output portion 202. The mounting portion 201 includes a mounting tube 203 and an input shaft 204. The mounting tube 203 is cylindrical and can be fitted to the front tube portion 9 of the front housing 3. A plurality of (three in this example) balls 205 are housed at the rear of the mounting tube 203 at equal intervals in the circumferential direction. Each ball 205 is movable radially around the mounting tube 203 and is biased to a protruding position from the inner surface of the mounting tube 203 by a ring-shaped leaf spring 206 fitted to the mounting tube 203. Four mounting recesses 207 are formed at equal intervals in the circumferential direction on the inner periphery of the rear end of the mounting tube 203. Each mounting recess 207 can be engaged from the front with a corresponding mounting protrusion 122 provided on the front housing 3. Operation windows 208 are formed at the top and bottom of the front of the mounting tube 203. A connecting plate 209 is formed in front of the operation windows 208. The input shaft 204 passes through the center of the connecting plate 209. The input shaft 204 is rotatably supported by a bearing 210 held in the connecting plate 209. The front portion of the input shaft 204 forms a pinion 211. The pinion 211 passes through the connecting plate 209 and protrudes forward. The rear portion of the input shaft 204 has a pair of recesses 212, 212 extending in the axial direction, and has the same size and shape as the bit B held at the tip of the tool holder 35.

[0048] The output section 202 includes a gear case 215 , a reduction section 216 , an output shaft 217 , and a torque adjustment section 218 . The gear case 215 is cylindrical in shape with two diameter stages and includes a large-diameter cylindrical portion 219, a disk portion 220, and a small-diameter cylindrical portion 221. The large-diameter cylindrical portion 219 has the same diameter as the connecting plate 209 of the mounting tube 203 and is screwed coaxially to the connecting plate 209. The pinion 211 protrudes coaxially into the large-diameter cylindrical portion 219. The disk portion 220 is ring-shaped and closes the front end of the large-diameter cylindrical portion 219. The disk portion 220 has multiple (six in this example) retaining holes 222, 222... formed to penetrate in the front-rear direction, and are arranged on concentric circles centered on the axis of the disk portion 220. The small-diameter cylindrical portion 221 protrudes forward from the center of the disk portion 220. 17B, ​​a threaded portion 223 and a plurality (six in this example) of guide grooves 224, 224... are formed on the outer periphery of small diameter cylindrical portion 221. The guide grooves 224 are arranged at equal intervals around the circumference of small diameter cylindrical portion 221, extend in the axial direction, and divide threaded portion 223 at equal intervals.

[0049] The reduction gear unit 216 includes an internal gear 225 , four planetary gears 226 , 226 . . . , and a carrier 227 . The internal gear 225 is rotatably held within the large diameter cylindrical portion 219 coaxially with the pinion 211. As shown in Figure 17A, a plurality of (here, six) engagement protrusions 228, 228... are formed on the front surface of the internal gear 225 in the circumferential direction and facing forward. The planetary gears 226 are disposed at equal intervals in the circumferential direction between the pinion 211 and the internal gear 225 within the large-diameter cylindrical portion 219. The planetary gears 226 are in mesh with the pinion 211 and the internal gear 225. The carrier 227 is disposed in front of the planetary gears 226 and rotatably supports each planetary gear 226 by four pins 229, 229 . . . The output shaft 217 is rotatably supported by a bearing 230 held within the small diameter cylindrical portion 221. The rear end of the output shaft 217 is splined to the center of the carrier 227 so as to be rotatable integrally with the carrier 227. The front portion of the output shaft 217 protrudes forward beyond the small diameter cylindrical portion 221. A chuck sleeve 231 to which a driver bit B1 can be attached and detached is provided at the front portion of the output shaft 217.

[0050] The torque adjustment portion 218 includes six balls 235 , a washer 236 , a pressure ring 237 , six coil springs 238 , a screw ring 239 , and an adjustment sleeve 240 . Each ball 235 is housed in a corresponding holding hole 222 of the disk portion 220 so as to be movable back and forth, and abuts against the front surface of the internal gear 225. A washer 236 is located on the front side of the disk portion 220 and abuts against each ball 235. The pressure ring 237 is fitted to the small diameter cylindrical portion 221. As shown in Fig. 17B, six protrusions 241, 241... are formed on the inner periphery of the pressure ring 237, which engage with the guide grooves 224 of the small diameter cylindrical portion 221. Therefore, the pressure ring 237 is able to move back and forth along the small diameter cylindrical portion 221 while its rotation is restricted. Six receiving bosses 242, 242... that protrude rearward are formed at equal intervals in the circumferential direction on the rear surface of the pressure ring 237. Each coil spring 238 is disposed between the washer 236 and the pressure ring 237. The front end of each coil spring 238 is supported by the corresponding receiving boss 242 of the pressure ring 237, and the rear end abuts against the washer 236. Therefore, the washer 236 is pressed against the front surface of the disk portion 220 by each coil spring 238. Each ball 235 is urged rearward via the washer 236 and presses against the front surface of the internal gear 225 between the engaging projections 228, 228, restricting rotation.

[0051] The screw ring 239 is fitted to the exterior of the small diameter cylindrical portion 221 in front of the pressure ring 237. The female screw portion provided on the inner periphery of the screw ring 239 is screwed into the screw portion 223 of the small diameter cylindrical portion 221. The pressure ring 237, which is urged forward by each coil spring 238, abuts against the screw ring 239. The adjustment sleeve 240 is fitted to the small-diameter cylindrical portion 221 outside the pressure ring 237, the coil springs 238, and the threaded ring 239. The adjustment sleeve 240 is rotatable while being prevented from coming off by a stop plate 243 that is screwed to the front end of the small-diameter cylindrical portion 221. The adjustment sleeve 240 engages with the threaded ring 239 inside the front side and holds the threaded ring 239 so that the threaded ring 239 can rotate integrally with the adjustment sleeve 240. Therefore, when the adjustment sleeve 240 is rotated, the threaded ring 239 that rotates integrally with the adjustment sleeve 240 is threaded forward and backward, and the pressure ring 237 that abuts against the threaded ring 239 also moves forward and backward. This changes the axial length of the coil springs 238, changing the pressing force applied to the internal gear 225 via the washer 236 and the balls 235.

[0052] In the adapter 200 configured as described above, the mounting tube 203 of the mounting portion 201 is fitted onto the front tube portion 9 from the front of the front housing 3 of the hammer drill 1A. At the same time, the rear end of the input shaft 204 is inserted into the tool holder 35 from the front end. Then, the positions of the mounting recesses 207 are aligned with the positions of the mounting protrusions 122, and the input shaft 204 is pushed in until they engage. As shown in FIG. 18 , the adapter 200 is mounted to the front housing 3 with the balls 205 fitted into the ring grooves 121 to prevent slippage and rotation. At this time, the balls 124, 124 held in the operating sleeve 38 engage with the recesses 212, 212 at the rear end, thereby connecting the input shaft 204 integrally in the rotational direction. To remove the adapter 200, the operating sleeve 38 is pushed rearward through the upper and lower operating windows 208, 208 of the mounting tube 203. Then, the input shaft 204 is unlocked, and the input shaft 204 can be removed from the tool holder 35 and the mounting tube 203 can be pulled forward and removed from the front housing 3. When the adapter 200 is attached to the hammer drill 1A in this manner, the axes of the input shaft 204 and the output shaft 217 are both positioned on the impact axis L of the hammer drill 1A, and the rotation of the tool holder 35 is transmitted to the input shaft 204.

[0053] In this state, when a driver bit B1 is attached to the output shaft 217 and a screw is to be tightened, the trigger 13 is pressed to turn on the switch 12, and the controller 16 drives the motor 6. This causes the rotary shaft 7 to rotate, causing the first gear 34 to rotate together with the rotary shaft 7 and decelerating the rotation of the intermediate shaft 36 via the second gear 57. Therefore, the rotation of the third gear 68 of the clutch gear 62 is transmitted to the tool holder 35 via the fourth gear 40. When the tool holder 35 rotates, the input shaft 204 of the adapter 200 also rotates at the same time, causing the planetary gear 226 to perform planetary motion within the internal gear 225 at the speed reducer 216. As a result, the output shaft 217 rotates at a reduced speed together with the carrier 227, making it possible to fasten screws with the driver bit B1. As the screw tightening progresses and the torque increases, the torque applied to the input shaft 204 exceeds the pressing force of the coil springs 238 on the internal gear 225 set in the torque adjustment unit 218, i.e., the torque setting value. Then, the balls 235 push the washers 236 forward against the bias of the coil springs 238, climbing over the engaging protrusions 228 and causing the internal gear 225 to idle. This interrupts the transmission of rotation by the speed reduction unit 216, and the rotation of the output shaft 217 stops. This torque setting value can be adjusted by rotating the adjustment sleeve 240 to thread-feed the screw ring 239 in the axial direction and changing the axial length of the coil springs 238.

[0054] As described above, the adapter 200 has a mounting portion 201 including a mounting cylinder 203 that can be mounted to the hammer drill 1A, and an input shaft 204 that is provided on the mounting cylinder 203 and can be mounted to the tool holder 35. The adapter 200 also has an output section 202 that is arranged in front of the mounting section 201 and includes a speed reducer 216 that reduces the rotation of the input shaft 204, an output shaft 217 to which the reduced rotation is transmitted and to which a driver bit B1 can be attached, and a torque adjustment section 218 that cuts off the transmission of rotation to the output shaft 217 when the torque applied to the output shaft 217 reaches a predetermined torque setting value. Therefore, even a hammer drill 1A that does not have a clutch mode can be used to perform screw tightening operations by attaching the adapter 200. This makes it possible to drill a pilot hole in a workpiece using the hammer drill 1A in hammer drill mode, and then attach the adapter 200 and perform screw tightening. This provides better usability than using two power tools, the hammer drill 1A and a screwdriver, without compromising the compactness of the hammer drill 1A itself.

[0055] In the adapter, the number and arrangement of balls in the mounting tube, the number of planetary gears in the reduction section, and the number of balls and coil springs in the torque adjustment section can be increased or decreased as appropriate.The mounting tube can also have a mounting structure that does not use balls, but instead uses an annular leaf spring that is tightened by screwing in a knob screw, like a side handle. In the torque adjusting portion, a coil spring is provided for each ball, but a single coil spring may be interposed between the washer and the pressure ring and fitted on the small diameter cylindrical portion. In the torque adjustment section, a plurality of balls that press the internal gear may be arranged in the front-rear direction, or pins extending in the front-rear direction may be used instead of balls. The threaded ring may be provided on its outer periphery so as to be movable back and forth only in the axial direction while its rotation is restricted relative to the small-diameter cylindrical portion. In this case, if a female thread is provided on the inner periphery of the adjustment sleeve so that the threaded portion of the threaded ring can be threaded back and forth by rotating the adjustment sleeve. [Explanation of symbols]

[0056] 1 hammer drill, 2 main body housing, 3 front housing, 4 motor housing, 5 inner housing, 6 motor, 7 rotating shaft, 10 rotating / impact mechanism, 12 switch, 16 controller, 18 operation panel, 27 guide recess, 30 inner support, 32 metal bearing, 35 tool holder, 36 intermediate shaft, 43 change plate, 44 receiving part, 50 striking part , 51··Piston cylinder, 52··Striker, 58··Rotation conversion section, 59··Boss sleeve, 61··Rod, 62··Clutch gear, 70··Mode switching section, 71··Regulating plate, 72··Cam mechanism section, 73··Operating lever, 74··Mode detection switch, 75··Base end section, 76··Regulating section, 80··Front cam, 81··Rear cam, 82··Conical spring, 100··Disc section, 101··Lever section, L··Impact axis.

Claims

1. A motor; a controller for controlling the driving of the motor; a cylindrical tool holder capable of holding a tool bit at a front end, accommodating a striking portion of the tool bit therein, and being rotatable in response to driving of the motor; a rotation conversion unit that converts the rotation of the motor into a striking motion of the striking unit; a mode switching member capable of switching between an active state and an inactive state of the rotation conversion unit, a hammer drill in which at least a hammer drill mode in which rotation of the tool holder and an impact action of the impact unit are simultaneously possible, and a rotation-only mode in which the tool holder is only capable of rotating, can be selected depending on the switching state of the rotation conversion unit by the mode switching member, When the rotation-only mode is selected, the hammer drill is further capable of selecting at least a first rotation mode and a second rotation mode in which the rotation control of the motor by the controller is different from each other.

2. 2. The hammer drill according to claim 1, further comprising an intermediate shaft that is arranged parallel to the tool holder to which rotation of the motor is transmitted and that transmits the rotation to the tool holder, and the rotation conversion portion is provided on the intermediate shaft.

3. 3. The hammer drill according to claim 1, wherein the first rotation mode is a clutch function enabled mode in which rotation of the motor is stopped by a predetermined torque applied to the tool holder, and the second rotation mode is a clutch function disabled mode.

4. 4. The hammer drill according to claim 3, wherein the torque is adjustable in the clutch function enabled mode.

5. 5. The hammer drill according to claim 3, wherein the maximum rotational speed of the motor in the clutch function-disabled mode is set higher than that in the clutch function-enabled mode.

6. 6. The hammer drill according to claim 3, wherein the time from when the motor is started until it reaches the maximum rotation speed is set longer in the clutch function mode than in the clutch function non-function mode.

7. The present invention further includes an operating member for operating the mode switching member to switch between a switching state to the hammer drill mode and a switching state to the rotation-only mode, and a position detection sensor for detecting an operating position of the operating member, 7. The hammer drill according to claim 1, wherein the controller is configured to select between the first rotation mode and the second rotation mode when the position detection sensor detects the operating position of the operating member that has switched the mode switching member to the rotation-only mode.

8. 8. The hammer drill according to claim 7, wherein when either the first rotation mode or the second rotation mode is selected in the rotation only mode, the controller stores the selected rotation mode, and when the rotation only mode is subsequently selected again after selection of the hammer drill mode, the controller automatically switches to the stored first rotation mode or the second rotation mode.

9. a main body housing that accommodates the motor, the tool holder, the rotation conversion unit, and the mode switching member, and a grip portion formed in a loop shape at a rear portion of the main body housing, 9. The hammer drill according to claim 7, wherein an operating unit that can select between the first rotation mode and the second rotation mode when the rotation-only mode is selected is provided on an inner surface of the loop-shaped portion in front of the grip portion.

10. 10. The hammer drill according to claim 9, wherein the grip portion houses a switch for driving the motor, the switch having a trigger protruding forward, and the operating member is disposed on an inner peripheral surface of the loop portion in front of the trigger.

11. 11. The hammer drill according to claim 1, wherein the rotation of the motor can be switched between forward and reverse directions.

12. 7. The hammer drill according to claim 3, wherein the rotation of the motor can be switched between forward and reverse, and when the rotation of the motor is switched to reverse rotation, the clutch function enabled mode is disabled.

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