Impact tool

Abstract

The invention provides an impact tool capable of improving the impact force of the impact tool. The impact tool includes: a motor; a main shaft that is rotated by the motor; a spindle groove formed in the spindle; a ball held in the spindle groove; a hammer supported by the main shaft by means of a ball; a spring that urges the hammer forward; and an anvil which is struck in the rotational direction by the hammer. The depth of the main shaft groove varies according to the axial position of the main shaft.

Description

Technical Field

[0001] The technology disclosed in this specification relates to an impact tool. Background Art

[0002] In the technical field related to impact tools, an impact rotation tool such as that disclosed in Patent Document 1 is known.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 4600562 Summary of the invention

[0006] In order to improve the workability when using an impact tool, a technology capable of increasing the striking force of the impact tool and thereby increasing the screw tightening speed is desired.

[0007] The purpose of the technology disclosed in this specification is to improve the striking force of an impact tool.

[0008] The present specification discloses an impact tool. The impact tool comprises: a motor; a spindle that is rotated by the motor; a spindle groove that is formed in the spindle; a ball that is held in the spindle groove; a hammer that is supported on the spindle by the ball; a spring that urges the hammer forward; and an anvil that is struck in a rotational direction by the hammer. The depth of the spindle groove varies depending on the axial position of the spindle.

[0009] Effects of the Invention

[0010] According to the technology disclosed in this specification, the striking force of the impact tool is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a perspective view showing the impact tool according to the embodiment when viewed from the front.

[0012] Figure 2 It is a side view showing an upper portion of the impact tool according to the embodiment.

[0013] Figure 3 It is a longitudinal sectional view showing the upper portion of the impact tool according to the embodiment.

[0014] Figure 4 It is a transverse cross-sectional view showing an upper portion of the impact tool according to the embodiment.

[0015] Figure 5 It is an exploded perspective view showing a part of the striking mechanism according to the embodiment when viewed from the front.

[0016] Figure 6It is an exploded perspective view showing a part of the striking mechanism according to the embodiment when viewed from the rear.

[0017] Figure 7 It is a side view showing the main shaft involved in the embodiment.

[0018] Figure 8 It is a top view showing the main shaft involved in the embodiment.

[0019] Fig. 9 It is a plan view showing a part of the main shaft according to the embodiment.

[0020] Fig.10 It is a perspective view showing a part of the main shaft according to the embodiment.

[0021] Fig.11 It is a longitudinal sectional view showing the main shaft according to the embodiment.

[0022] Fig.12 It is a cross-sectional view showing a main shaft according to the embodiment.

[0023] Fig.13 It is a side view which shows the hammer which concerns on embodiment.

[0024] Fig.14 It is a longitudinal sectional view showing the hammer according to the embodiment.

[0025] Fig.15 It is a cross-sectional view showing a hammer according to the embodiment.

[0026] Fig.16 It is a perspective view showing a main shaft according to the embodiment.

[0027] Fig.17 It is a cross-sectional view for explaining the operation of the striking mechanism according to the embodiment.

[0028] Fig.18 It is a cross-sectional view for explaining the operation of the striking mechanism according to the embodiment.

[0029] Fig.19 It is a cross-sectional view for explaining the operation of the striking mechanism according to the embodiment.

[0030] Fig. 20 It is a plan view showing a part of a main shaft according to a comparative example.

[0031] Fig.21 It is a diagram for explaining the relationship between the main shaft and the ball according to each of the embodiment and the comparative example.

[0032] Fig. 22It is a diagram for explaining the force received by the ball from the main shaft according to each of the embodiment and the comparative example.

[0033] Fig.23 It is a diagram for explaining the striking start torque according to each of the embodiment and the comparative example.

[0034] Fig.24 It is a graph showing the fastening speed, average current, and average voltage according to each of the embodiment and the comparative example.

[0035] Fig.25 It is a diagram showing the direction in which the load is transmitted from the ball to the weight according to each of the embodiment and the comparative example.

[0036] Description of Reference Numerals

[0037] 1…impact tool; 2…housing; 2L…left housing; 2R…right housing; 2S…screw; 3…rear cover; 3S…screw; 4…hammer housing; 4A…support surface; 4B…groove; 5…hammer housing cover; 6…motor; 7…speed reduction mechanism; 8…spindle; 8A…flange; 8B…spindle shaft; 8C…convex portion; 8D…spindle groove; 8E…spindle recess; 8S…peripheral surface; 9…strike mechanism; 10…anvil; 10A…tool hole; 10B…anvil convex portion; 11…tool holding mechanism; 12…fan; 12A…bushing; 13…battery mounting portion; 14…trigger shifter; 15…forward / reverse switching shifter; 16…operation display portion; 1 6A…operation button; 17…mode switch; 18…lamp assembly; 18A…base member; 18B…light emitting element; 18C…ring member; 19…air inlet; 20…exhaust port; 21…motor housing; 22…grip; 23…battery holding portion; 24…bearing box; 24A…recess; 24B…convex; 25…battery pack; 26…stator; 27…rotor; 28…stator core; 29…front insulator; 29S…screw; 30…rear insulator; 31…coil; 32…rotor core; 33…rotor shaft; 33F…front shaft; 33R…rear shaft; 34…rotor magnet; 35…sensor magnet; 36…rotor magnet; 37…rotor magnet; 38…rotor magnet; 39…rotor magnet; 40…rotor magnet; 41…rotor magnet; 42…rotor magnet; 43…rotor magnet; 44…rotor magnet; 45…sensor magnet; 46…rotor magnet; 47…rotor magnet; 48…rotor magnet; 49…rotor magnet; 50…rotor magnet; 51…rotor magnet; 52…rotor magnet; 53…rotor magnet; 54…rotor magnet; 55…rotor magnet; 56…rotor magnet; 57…rotor magnet; 58…rotor magnet; 59…rotor magnet; 60…operation button; 10…mode switch; 11…lamp assembly; 12…base member; 13…light emitting element; 14…light emitting element; 15… 7…Sensor substrate; 38…Fuse terminal; 39…Rotor bearing; 39F…Front rotor bearing; 39R…Rear rotor bearing; 41…Pinion gear; 42…Planet gear; 42P…Pin; 43…Internal gear; 44…Spindle bearing; 45…O-ring; 45A…O-ring; 45B…O-ring; 46…Bearing; 46A…Bearing; 46B…Bearing; 47…Hammer; 47A…Hole; 47B…Hammer groove; 47C…Concave portion; 47D…Hammer body; 47E…Hammer protrusion; 47F…Contact point; 48…Ball; 48C…Center; 49…1st coil spring; 50…2nd coil spring; 51…3rd coil spring; 5 2…1st washer; 53…2nd washer; 54…ball; 61…annular member; 62…suppression member; 71…ball; 72…leaf spring; 73…sleeve; 74…coil spring; 75…positioning member; 76…support recess; 81…central portion; 82…end portion; 90…imaginary circle; 90C…center; 91…imaginary plane; 92…cutting tool; 92C…center; 101…anvil shaft portion; 102…anvil protrusion portion; 401…1st barrel portion; 402…2nd barrel portion; 800…spindle; 800B…spindle shaft portion; 800D…spindle groove; 820…end portion; AX…rotation axis; Da…diameter; Vc…arrow; Ve…arrow. DETAILED DESCRIPTION

[0038] In one or more embodiments, the impact tool includes: a motor; a spindle that is rotated by the motor; a spindle groove formed in the spindle; a ball that is held in the spindle groove; a hammer that is supported on the spindle by the ball; a spring that urges the hammer forward; and an anvil that is struck in a rotational direction by the hammer. The depth of the spindle groove varies depending on the axial position of the spindle.

[0039] When a load torque exceeding a specified value is applied from the screw to the anvil during the screw tightening operation, the rotation of the anvil and the hammer stops. Since the spindle is continuously rotated by the motor, when the spindle continues to rotate while the hammer stops rotating, the hammer moves backward relative to the spindle. After the hammer moves backward, the hammer moves forward while rotating due to the force of the spring. The anvil is struck by the hammer in the rotational direction by the hammer while rotating and moving forward. In the above-mentioned structure, the depth of the spindle groove varies depending on the axial position of the spindle, so the component of the rotational direction of the force acting between the spindle and the ball becomes larger. Accordingly, the rotational speed of the hammer when the hammer moves forward while rotating is increased. Since the rotational speed of the hammer is increased, the hammer can strike the anvil with a greater striking force.

[0040] In addition, the component of the force acting between the main shaft and the ball in the rotation direction becomes larger and the component in the axial direction becomes smaller, so even if the spring coefficient of the spring is small, the spring can still apply force to the hammer forward. That is, even if the force of the spring is small, the hammer can move forward while rotating due to the force of the spring. By using a spring with a small force, the timing of the hammer striking the anvil can be advanced. That is, the period from the moment the hammer stops rotating to the moment the hammer strikes the anvil is shortened.

[0041] In the screw tightening operation, the anvil rotates while the front end tool mounted on the anvil is inserted into the cross groove formed in the head of the screw. In the case where the timing of the hammer striking the anvil is late, that is, when the screw rotates a lot from the start of screw tightening to the time when the hammer strikes the anvil, the possibility of the cam-out phenomenon (cam-out phenomenon) in which the front end tool is separated from the cross groove becomes high. In the above-mentioned structure, the timing of the hammer striking the anvil is advanced, so the occurrence of the cam-out phenomenon can be suppressed.

[0042] In one or more embodiments, the end of the spindle groove is arranged at a position further rearward than the center of the spindle groove. When the hammer moves rearward relative to the spindle, the ball moves toward the end of the spindle groove. The depth of the end of the spindle groove is deeper than a certain point between the center and the end of the spindle groove.

[0043] When the hammer moves backward relative to the main shaft, the ball moves from the center to the end of the main shaft groove. When the hammer moves forward relative to the main shaft due to the force of the spring, the ball moves from the end to the center of the main shaft groove. In the above structure, the center of the ball sinks to the inner position of the main shaft groove at the end of the main shaft groove, so the rotation speed of the hammer is increased when the hammer moves forward while rotating. Since the rotation speed of the hammer is increased, the hammer can strike the anvil with a greater striking force.

[0044] In one or more embodiments, in the center portion of the main shaft groove, the center of the ball is arranged at an outer position of the main shaft groove.

[0045] When the hammer strikes the anvil, the ball moves from the end of the main shaft groove toward the center. In the above configuration, the center of the ball is arranged at the outer side of the main shaft groove in the center of the main shaft groove, so the rotation speed of the hammer is increased at the moment the hammer strikes the anvil. Since the rotation speed of the hammer is increased, the hammer can strike the anvil with a greater striking force.

[0046] In one or more embodiments, the spindle has a flange portion supporting the rear end of the spring and a spindle shaft portion protruding forward from the flange portion. The spindle groove is formed in the spindle shaft portion. The track of the center of the ball enters into the width of the spindle shaft portion.

[0047] In the above-described configuration, the moving range of the ball is small, so that the rotation speed of the hammer can be increased and the size of the impact tool can be suppressed.

[0048] In one or more embodiments, the track is arc-shaped.

[0049] In the above structure, the ball moves in a circular motion along an imaginary circle with a small radius. As a result, the hammer can smoothly rotate and move in the axial direction. The sliding resistance of the hammer is reduced, so the rotation speed of the hammer is increased. As a result, the hammer can strike the anvil with a greater striking force.

[0050] In one or more embodiments, the ball can perform circular motion in a virtual plane that is inclined at a predetermined angle with respect to the rotation axis of the spindle.

[0051] In the above structure, the sliding resistance of the hammer is reduced, so the rotation speed of the hammer is increased. According to this, the hammer can strike the anvil with a large striking force.

[0052] In one or more embodiments, the ball moves in a circular motion such that the center of the ball moves along an imaginary circle defined by the imaginary plane. The center of the imaginary circle is defined at a position offset from the rotation axis of the spindle.

[0053] In the above configuration, the hammer can strike the anvil with a large striking force.

[0054] In one or more embodiments, the spindle has a flange portion supporting the rear end portion of the spring and a spindle shaft portion protruding forward from the flange portion. The spindle groove is formed in the spindle shaft portion. The diameter of the imaginary circle is smaller than the diameter of the spindle shaft portion.

[0055] In the above-described configuration, the moving range of the ball is small, so that the rotation speed of the hammer can be increased and the size of the impact tool can be suppressed.

[0056] Hereinafter, the embodiment will be described with reference to the accompanying drawings. In the embodiment, the terms such as front, rear, left, right, top, and bottom are used to describe the positional relationship of each part. The above terms represent: relative position or direction based on the center of the impact tool 1. The impact tool 1 has a motor 6 as a power source.

[0057] In the embodiment, a direction parallel to the rotation axis AX of the motor 6 is appropriately referred to as an axial direction, a direction around the rotation axis AX is appropriately referred to as a circumferential direction or a rotation direction, and a radial direction of the rotation axis AX is appropriately referred to as a radial direction.

[0058] The rotation axis AX extends along the front-to-back direction. One axial side is the front, and the other axial side is the rear. In addition, in the radial direction, a position closer to the rotation axis AX or a direction close to the rotation axis AX is appropriately referred to as the radial inner side, and a position farther from the rotation axis AX or a direction away from the rotation axis AX is appropriately referred to as the radial outer side.

[0059] [Impact tools]

[0060] Figure 1 It is a perspective view showing the impact tool 1 according to the embodiment when viewed from the front. Figure 2 It is a side view showing the upper part of the impact tool 1 according to the embodiment. Figure 3 It is a longitudinal sectional view showing the upper portion of the impact tool 1 according to the embodiment. Figure 4 It is a transverse cross-sectional view showing an upper portion of the impact tool 1 according to the embodiment.

[0061] In the embodiment, the impact tool 1 is an impact driver as a type of screw fastening tool. The impact tool 1 includes a housing 2, a rear cover 3, a hammer housing 4, a hammer housing cover 5, a motor 6, a speed reduction mechanism 7, a spindle 8, a striking mechanism 9, an anvil 10, a tool holding mechanism 11, a fan 12, a battery mounting portion 13, a trigger shifter 14, a forward / reverse switching shifter 15, an operation display portion 16, a mode switching switch 17, and a light assembly 18.

[0062] The housing 2 is made of synthetic resin. In the embodiment, the housing 2 is made of nylon. The housing 2 includes a left housing 2L and a right housing 2R disposed to the right of the left housing 2L. The left housing 2L and the right housing 2R are fixed by a plurality of screws 2S. The housing 2 is composed of a pair of half-split housings.

[0063] The housing 2 includes a motor housing portion 21 , a grip portion 22 , and a battery holding portion 23 .

[0064] The motor housing portion 21 has a cylindrical shape. The motor housing portion 21 houses the motor 6. The motor housing portion 21 houses at least a portion of the hammer case 4.

[0065] The grip portion 22 extends downward from the motor housing portion 21. The trigger lever 14 is provided on the upper portion of the grip portion 22. The grip portion 22 is gripped by an operator.

[0066] The battery holding portion 23 is connected to the lower end portion of the grip portion 22. The outer dimensions of the battery holding portion 23 are larger than the outer dimensions of the grip portion 22 in the front-rear direction and the left-right direction.

[0067] The rear cover 3 is made of synthetic resin. The rear cover 3 is arranged at the rear position of the motor housing portion 21. The rear cover 3 accommodates at least a part of the fan 12. The fan 12 is arranged at the inner peripheral side of the rear cover 3. The rear cover 3 is arranged to cover the opening of the rear end portion of the motor housing portion 21. The rear cover 3 is fixed to the rear end portion of the motor housing portion 21 by two screws 3S.

[0068] The motor housing portion 21 has an air inlet 19. The rear cover 3 has an air outlet 20. The air in the external space of the housing 2 flows into the internal space of the housing 2 through the air inlet 19. The air in the internal space of the housing 2 flows out to the external space of the housing 2 through the air outlet 20.

[0069] The hammer housing 4 is made of metal. In the embodiment, the hammer housing 4 is made of aluminum. The hammer housing 4 is cylindrical. The hammer housing 4 is connected to the front of the motor housing 21. A bearing box 24 is fixed to the rear of the hammer housing 4. Threads are formed on the outer periphery of the bearing box 24. Thread grooves are formed on the inner periphery of the hammer housing 4. The bearing box 24 is fixed to the hammer housing 4 by combining the threads of the bearing box 24 with the thread grooves of the hammer housing 4. The hammer housing 4 is clamped by the left housing 2L and the right housing 2R. At least a portion of the hammer housing 4 is accommodated in the motor housing 21. The bearing box 24 is fixed to the motor housing 21 and the hammer housing 4, respectively.

[0070] The hammer case 4 accommodates at least a part of the speed reduction mechanism 7, the spindle 8, the striking mechanism 9, and the anvil 10. At least a part of the speed reduction mechanism 7 is arranged inside the bearing box 24. The speed reduction mechanism 7 has a plurality of gears.

[0071] The hammer case 4 includes a first tube 401 and a second tube 402. The first tube 401 is disposed around the striking mechanism 9. The second tube 402 is disposed further forward than the first tube 401. The outer diameter of the second tube 402 is smaller than that of the first tube 401.

[0072] The hammer case cover 5 covers at least a part of the surface of the hammer case 4 . The hammer case cover 5 protects the hammer case 4 . The hammer case cover 5 can suppress contact between the hammer case 4 and an object around the hammer case 4 .

[0073] The motor 6 is a power source of the impact tool 1. The motor 6 is an inner rotor type brushless motor. The motor 6 includes a stator 26 and a rotor 27. The stator 26 is supported by the motor housing portion 21. At least a portion of the rotor 27 is arranged at an inner position of the stator 26. The rotor 27 rotates relative to the stator 26. The rotor 27 rotates around a rotation axis AX extending in the front-rear direction.

[0074] The stator 26 includes a stator core 28 , a front insulator 29 , a rear insulator 30 , and a coil 31 .

[0075] The stator core 28 is arranged radially outward from the rotor 27. The stator core 28 includes a plurality of stacked steel plates. The steel plates are metal plates mainly composed of iron. The stator core 28 is cylindrical. The stator core 28 has a plurality of teeth for supporting the coil 31.

[0076] The front insulator 29 is provided at the front of the stator core 28. The rear insulator 30 is provided at the rear of the stator core 28. The front insulator 29 and the rear insulator 30 are respectively electrical insulating members made of synthetic resin. The front insulator 29 is arranged to cover a part of the surface of the tooth. The rear insulator 30 is arranged to cover a part of the surface of the tooth.

[0077] The coil 31 is mounted on the stator core 28 via the front insulator 29 and the rear insulator 30. A plurality of coils 31 are arranged. The coil 31 is arranged around the teeth of the stator core 28 via the front insulator 29 and the rear insulator 30. The coil 31 is electrically insulated from the stator core 28 by the front insulator 29 and the rear insulator 30. The plurality of coils 31 are connected via the fuse terminal 38.

[0078] The rotor 27 rotates around the rotation axis AX and includes a rotor core portion 32 , a rotor shaft portion 33 , a rotor magnet 34 , and a sensor magnet 35 .

[0079] The rotor core portion 32 and the rotor shaft portion 33 are each made of steel. The rotor shaft portion 33 protrudes in the front-rear direction from the end surface of the rotor core portion 32. The rotor shaft portion 33 includes a front shaft portion 33F protruding forward from the front end surface of the rotor core portion 32, and a rear shaft portion 33R protruding rearward from the rear end surface of the rotor core portion 32.

[0080] The rotor magnet 34 is fixed to the rotor core portion 32 . The rotor magnet 34 is cylindrical. The rotor magnet 34 is arranged around the rotor core portion 32 .

[0081] The sensor magnet 35 is fixed to the rotor core portion 32 . The sensor magnet 35 is in an annular shape. The sensor magnet 35 is disposed on the front end surface of the rotor core portion 32 and the front end surface of the rotor magnet 34 .

[0082] The sensor substrate 37 is mounted on the front insulator 29. The sensor substrate 37 is fixed to the front insulator 29 by screws 29S. The sensor substrate 37 includes a disc-shaped circuit substrate having a hole at the center and a rotation detection element supported by the circuit substrate. At least a portion of the sensor substrate 37 is opposed to the sensor magnet 35. The rotation detection element detects the position of the rotor 27 in the rotation direction by detecting the position of the sensor magnet 35 of the rotor 27.

[0083] The rotor shaft portion 33 is rotatably supported by a rotor bearing 39. The rotor bearing 39 includes a front rotor bearing 39F that rotatably supports the front shaft portion 33F and a rear rotor bearing 39R that rotatably supports the rear shaft portion 33R.

[0084] The front rotor bearing 39F is held by the bearing box 24. The bearing box 24 has a recessed portion 24A that is recessed from the rear surface of the bearing box 24 toward the front. The front rotor bearing 39F is arranged in the recessed portion 24A. The rear rotor bearing 39R is held by the rear cover 3. The front end portion of the rotor shaft portion 33 is arranged in the internal space of the hammer case 4 through the opening of the bearing box 24.

[0085] A pinion gear 41 is formed at the front end portion of the rotor shaft portion 33. The pinion gear 41 is connected to at least a portion of the speed reduction mechanism 7. The rotor shaft portion 33 is connected to the speed reduction mechanism 7 via the pinion gear 41.

[0086] The speed reduction mechanism 7 is arranged at a position further forward than the motor 6. The speed reduction mechanism 7 connects the rotor shaft 33 and the main shaft 8. The speed reduction mechanism 7 transmits the rotation of the rotor 27 to the main shaft 8. The speed reduction mechanism 7 rotates the main shaft 8 at a rotation speed lower than the rotation speed of the rotor shaft 33. The speed reduction mechanism 7 includes a planetary gear mechanism.

[0087] The speed reduction mechanism 7 includes a plurality of gears. The gears of the speed reduction mechanism 7 are driven by the rotor 27 .

[0088] The speed reduction mechanism 7 includes a plurality of planetary gears 42 arranged around the pinion gear 41, and an internal gear 43 arranged around the plurality of planetary gears 42. The pinion gear 41, the planetary gears 42, and the internal gear 43 are respectively accommodated in the hammer housing 4. The plurality of planetary gears 42 are respectively meshed with the pinion gear 41. The planetary gears 42 are rotatably supported on the main shaft 8 by means of pins 42P. The main shaft 8 is rotated by the planetary gears 42. The internal gear 43 has internal teeth meshing with the planetary gears 42. The internal gear 43 is fixed to the hammer housing 4. The internal gear 43 cannot always rotate relative to the hammer housing 4.

[0089] When the rotor shaft 33 is rotated by the drive of the motor 6, the pinion 41 rotates, and the planetary gear 42 revolves around the pinion 41. The planetary gear 42 revolves while meshing with the internal teeth of the internal gear 43. The main shaft 8 connected to the planetary gear 42 via the pin 42P rotates at a rotation speed lower than the rotation speed of the rotor shaft 33 due to the revolution of the planetary gear 42.

[0090] The spindle 8 is arranged at a position closer to the front than at least a part of the motor 6. The spindle 8 is arranged at a position closer to the front than the stator 26. At least a part of the spindle 8 is arranged at a position closer to the front than the rotor 27. At least a part of the spindle 8 is arranged in front of the speed reduction mechanism 7. The spindle 8 is arranged behind the anvil 10. The spindle 8 is rotated by the rotor 27. The spindle 8 is rotated by the rotational force of the rotor 27 transmitted by the speed reduction mechanism 7. The spindle 8 transmits the rotational force of the motor 6 to the anvil 10 via the ball 48 and the hammer 47.

[0091] The main shaft 8 has a flange portion 8A and a main shaft portion 8B protruding forward from the flange portion 8A. The planetary gear 42 is supported by the flange portion 8A by means of a pin 42P in a rotatable manner. The rotation axis of the main shaft 8 coincides with the rotation axis AX of the motor 6. The main shaft 8 rotates around the rotation axis AX. The main shaft 8 is supported by the main shaft bearing 44 in a rotatable manner. A convex portion 8C is provided at the rear end portion of the main shaft 8. The convex portion 8C protrudes backward from the flange portion 8A. The convex portion 8C is configured to surround the main shaft bearing 44.

[0092] The bearing box 24 is arranged at least partially around the spindle 8. The spindle bearing 44 is held by the bearing box 24. The bearing box 24 has a convex portion 24B protruding forward from the front surface of the bearing box 24. The spindle bearing 44 is arranged around the convex portion 24B.

[0093] The striking mechanism 9 is driven by the motor 6. The rotational force of the motor 6 is transmitted to the striking mechanism 9 via the speed reduction mechanism 7 and the main shaft 8. The striking mechanism 9 strikes the anvil 10 in the rotational direction based on the rotational force of the main shaft 8 rotated by the motor 6. The striking mechanism 9 includes a hammer 47, a ball 48, a first coil spring 49, a second coil spring 50, a third coil spring 51, a first washer 52, and a second washer 53. The striking mechanism 9 including the hammer 47, the ball 48, the first coil spring 49, the second coil spring 50, the third coil spring 51, the first washer 52, and the second washer 53 is accommodated in the first cylinder 401 of the hammer housing 4.

[0094] The hammer 47 is arranged at a position closer to the front than the speed reduction mechanism 7. The hammer 47 is arranged around the main shaft 8. The hammer 47 is held by the main shaft 8. The ball 48 is arranged at a position between the main shaft 8 and the hammer 47. The hammer 47 has a cylindrical hammer body 47D and a hammer protrusion 47E provided at a front position of the hammer body 47D. An annular recess 47C is provided on the rear surface of the hammer body 47D. The recess 47C is recessed from the rear surface of the hammer body 47D toward the front.

[0095] The hammer 47 is arranged around the main shaft portion 8B. The hammer 47 has a hole 47A for arranging the main shaft portion 8B.

[0096] The hammer 47 is rotated by the motor 6. The rotational force of the motor 6 is transmitted to the hammer 47 via the speed reduction mechanism 7 and the main shaft 8. The hammer 47 can rotate together with the main shaft 8 based on the rotational force of the main shaft 8 rotated by the motor 6. The rotation axis of the hammer 47, the rotation axis of the main shaft 8, and the rotation axis AX of the motor 6 are consistent. The hammer 47 rotates around the rotation axis AX.

[0097] The first washer 52 is arranged at an inner side of the recessed portion 47C. The first washer 52 is supported by the hammer 47 via a plurality of balls 54. The balls 54 are arranged at a frontward position relative to the first washer 52.

[0098] The second washer 53 is disposed inside the recess 47C and further rearward than the first washer 52. The outer diameter of the second washer 53 is smaller than that of the first washer 52. The second washer 53 and the hammer 47 are relatively movable in the front-rear direction.

[0099] The first coil spring 49 is arranged around the spindle shaft 8B. The rear end of the first coil spring 49 is supported by the flange 8A. The front end of the first coil spring 49 is arranged inside the recess 47C and supported by the first washer 52. The first coil spring 49 always generates a force (elastic force) for moving the hammer 47 forward.

[0100] The second coil spring 50 is arranged around the spindle shaft 8B. The second coil spring 50 is arranged at a radially inner position of the first coil spring 49. The rear end of the second coil spring 50 is supported by the flange 8A. The front end of the second coil spring 50 is arranged at an inner position of the recess 47C and is supported by the second washer 53. The second coil spring 50 generates a force (elastic force) for moving the hammer 47 toward the front when the hammer 47 moves to the rear.

[0101] The third coil spring 51 is arranged around the spindle shaft 8B. The third coil spring 51 is arranged at the radially inner side of the first coil spring 49. The third coil spring 51 is arranged at the inner side of the recess 47C. The rear end of the third coil spring 51 is supported by the second washer 53. The front end of the third coil spring 51 is supported by the first washer 52. The third coil spring 51 generates a force (elastic force) for moving the second coil spring 50 backward. The rear end of the second coil spring 50 is pressed against the flange 8A by the force of the third coil spring 51. Thus, the second coil spring 50 can be restrained from freely moving relative to the flange 8A.

[0102] The ball 48 is made of metal such as steel. The ball 48 is arranged at a position between the main shaft portion 8B and the hammer 47. The main shaft 8 has a main shaft groove 8D for arranging at least a part of the ball 48. The main shaft groove 8D is provided at a part of the outer peripheral surface 8S of the main shaft portion 8B. The hammer 47 has a hammer groove 47B for arranging at least a part of the ball 48. The hammer groove 47B is provided at a part of the inner surface of the hammer 47. The ball 48 is arranged at a position between the main shaft groove 8D and the hammer groove 47B. The ball 48 can roll on the inner side of the main shaft groove 8D and the inner side of the hammer groove 47B respectively. The hammer 47 can move along with the ball 48. The main shaft 8 and the hammer 47 can move relative to each other in the axial direction and the rotational direction within the movable range defined by the main shaft groove 8D and the hammer groove 47B.

[0103] The anvil 10 is arranged at a position closer to the front than the motor 6. The anvil 10 is an output part of the impact tool 1 that rotates based on the rotational force of the rotor 27. At least a part of the anvil 10 is arranged at a position closer to the front than the hammer 47. The anvil 10 has a tool hole 10A for inserting a front end tool. The tool hole 10A is provided at the front end of the anvil 10. The front end tool is mounted on the anvil 10.

[0104] The anvil 10 has an anvil convex portion 10B. The anvil convex portion 10B is provided at the rear end portion of the anvil 10. The anvil convex portion 10B protrudes rearward from the rear end portion of the anvil 10. The spindle 8 is arranged at the rear of the anvil 10. The spindle recess 8E is provided at the front end portion of the spindle shaft portion 8B. The anvil convex portion 10B is arranged in the spindle recess 8E.

[0105] The anvil 10 has a rod-shaped anvil shaft 101 and an anvil protrusion 102. The tool hole 10A is provided at the front end of the anvil shaft 101. The front end tool is mounted on the anvil shaft 101. The anvil protrusion 102 is provided at the rear end of the anvil 10. The anvil protrusion 102 protrudes radially outward from the rear end of the anvil shaft 101.

[0106] The anvil 10 is rotatably supported by the bearing 46. The rotation axis of the anvil 10, the rotation axis of the hammer 47, the rotation axis of the spindle 8, and the rotation axis AX of the motor 6 are consistent. The anvil 10 rotates around the rotation axis AX. The bearing 46 is arranged around the anvil shaft portion 101. The bearing 46 is arranged at an inner position of the second cylinder portion 402 of the hammer housing 4. The bearing 46 is held by the second cylinder portion 402 of the hammer housing 4. The bearing 46 supports the front portion of the anvil shaft portion 101 so that it can rotate.

[0107] An O-ring 45 is disposed between the bearing 46 and the anvil shaft portion 101. The O-ring 45 is in contact with the outer peripheral portion of the anvil shaft portion 101 and the inner peripheral portion of the bearing 46, respectively.

[0108] In the embodiment, two bearings 46 are arranged in the axial direction. The bearing 46 includes a bearing 46A and a bearing 46B arranged at a rearward position relative to the bearing 46A.

[0109] In the embodiment, two O-rings 45 are arranged in the axial direction. The O-ring 45 includes an O-ring 45A and an O-ring 45B arranged at a position further back than the O-ring 45A. The O-ring 45A is arranged at a position between the bearing 46A and the anvil shaft portion 101. The O-ring 45B is arranged at a position between the bearing 46B and the anvil shaft portion 101.

[0110] The bearing 46 is a ball bearing. The bearing 46 has an inner ring, balls, and an outer ring. The inner ring of the bearing 46A contacts the O-ring 45A. The inner ring of the bearing 46B contacts the O-ring 45B. The balls of the bearing 46 are arranged in the radial direction at a position between the inner ring and the outer ring. The balls of the bearing 46 are in contact with the inner ring and the outer ring, respectively. There are multiple balls of the bearing 46 arranged in the circumferential direction. The outer ring is arranged at a position closer to the radial outside than the inner ring and the balls. The outer ring of the bearing 46A contacts the inner circumferential surface of the second cylinder 402. The outer ring of the bearing 46B contacts the inner circumferential surface of the second cylinder 402.

[0111] At least a portion of the hammer 47 can contact the anvil protrusion 102. A hammer protrusion 47E protruding forward is provided at the front of the hammer 47. The hammer protrusion 47E can contact the anvil protrusion 102. When the hammer 47 is in contact with the anvil protrusion 102, the motor 6 is driven to rotate the anvil 10 together with the hammer 47 and the spindle 8.

[0112] The anvil 10 is struck in the rotation direction by the hammer 47. For example, in the screw tightening operation, when the load acting on the anvil 10 becomes large, sometimes it occurs that the anvil 10 cannot be rotated only by the load of the first coil spring 49. When the anvil 10 cannot be rotated only by the load of the first coil spring 49, the rotation of the anvil 10 and the hammer 47 will stop. The spindle 8 and the hammer 47 can move relative to each other in the axial direction and the circumferential direction respectively by means of the ball 48. Even if the rotation of the hammer 47 stops, the rotation of the spindle 8 will continue by the power generated by the motor 6. In the state where the rotation of the hammer 47 stops, when the spindle 8 rotates, the ball 48 moves toward the rear while being guided by the spindle groove 8D and the hammer groove 47B respectively. The hammer 47 receives force from the ball 48 and moves toward the rear along with the ball 48. That is, when the rotation of the anvil 10 is stopped, the hammer 47 is moved backward by the rotation of the spindle 8. When the hammer 47 moves backward, the contact between the hammer 47 and the anvil protrusion 102 is released.

[0113] As described above, the first coil spring 49 always generates a force for moving the hammer 47 forward. The second coil spring 50 generates a force for moving the hammer 47 forward after the hammer 47 moves to a position further rearward than a predetermined position. The hammer 47 moved to the rear moves forward by the force of the first coil spring 49 and the second coil spring 50. When the hammer 47 moves forward, it receives a force in the rotation direction from the ball 48. That is, the hammer 47 moves forward while rotating. When the hammer 47 moves forward while rotating, the hammer 47 contacts the anvil protrusion 102 while rotating. As a result, the anvil protrusion 102 is struck in the rotation direction by the hammer protrusion 47E of the hammer 47. Both the power of the motor 6 and the inertia force of the hammer 47 act on the anvil 10. Therefore, the anvil 10 can rotate around the rotation axis AX with a high torque.

[0114] The tool holding mechanism 11 is disposed around the front portion of the anvil 10. The tool holding mechanism 11 holds a tip tool inserted into the tool hole 10A of the anvil 10. The tool holding mechanism 11 can attach and detach the tip tool.

[0115] The tool holding mechanism 11 includes a ball 71 , a leaf spring 72 , a sleeve 73 , a coil spring 74 , and a positioning member 75 .

[0116] The anvil 10 has a support recess 76 for supporting the ball 71. The support recess 76 is formed in the outer peripheral surface 8S of the anvil shaft portion 101. In the embodiment, two support recesses 76 are formed in the anvil shaft portion 101.

[0117] The ball 71 is movably supported by the anvil 10. The ball 71 is arranged in the support recess 76. One ball 71 is arranged in one support recess 76.

[0118] The anvil shaft portion 101 is formed with a through hole that connects the inner surface of the support recess 76 with the inner surface of the tool hole 10A. When the ball 71 is supported by the support recess 76, at least a portion of the ball 71 is arranged inside the tool hole 10A. The ball 71 can fix the front end tool inserted into the tool hole 10A. The ball 71 can move to an engagement position for fixing the front end tool and a release position for releasing the fixation of the front end tool.

[0119] The leaf spring 72 generates an elastic force for moving the ball 71 toward the engagement position. The leaf spring 72 is disposed around the anvil shaft portion 101. The leaf spring 72 generates an elastic force for moving the ball 71 toward the radial inner side.

[0120] The sleeve 73 is a cylindrical component. The sleeve 73 is arranged around the anvil shaft 101. The sleeve 73 can move axially around the anvil shaft 101. The sleeve 73 can prevent the ball 71 arranged at the engaging position from being disengaged from the engaging position. By moving along the axial direction, the sleeve 73 can change the state of the ball 71 from the engaging position to the releasing position.

[0121] The sleeve 73 is movable around the anvil shaft portion 101 between a blocking position for blocking the balls 71 from moving radially outward and a allowing position for allowing the balls 71 to move radially outward.

[0122] By placing the sleeve 73 at the blocking position, it is possible to suppress the ball 71 placed at the engagement position from moving radially outward. In other words, by placing the sleeve 73 at the blocking position, it is possible to prevent the ball 71 placed at the engagement position from escaping from the engagement position. By placing the sleeve 73 at the blocking position, it is possible to maintain the state in which the tip tool is fixed by the ball 71.

[0123] By moving the sleeve 73 to the permitted position, the ball 71 arranged at the engaging position is permitted to move radially outward. By moving the sleeve 73 to the permitted position, the ball 71 is changed to a state where it can move from the engaging position to the release position. That is, by arranging the sleeve 73 at the permitted position, the ball 71 arranged at the engaging position is permitted to be disengaged from the engaging position. By arranging the sleeve 73 at the permitted position, the state where the tip tool is fixed by the ball 71 can be released.

[0124] The coil spring 74 generates an elastic force to move the sleeve 73 toward the blocking position. The coil spring 74 is disposed around the anvil shaft 101. The blocking position is defined as a position further rearward than the allowing position. The coil spring 74 generates an elastic force to move the sleeve 73 rearward.

[0125] The positioning member 75 is an annular member fixed to the outer peripheral surface 8S of the anvil shaft portion 101. The positioning member 75 is fixed to a position that can be opposite to the rear end portion of the sleeve 73. The positioning member 75 positions the sleeve 73 at the blocking position. The sleeve 73, which is given an elastic force to move backward by the coil spring 74, is positioned at the blocking position by contacting the positioning member 75.

[0126] The fan 12 is arranged at a position further rearward than the stator 26 of the motor 6. The fan 12 generates an airflow for cooling the motor 6. The fan 12 is fixed to at least a portion of the rotor 27. The fan 12 is fixed to the rear of the rear shaft portion 33R by means of a bushing 12A. The fan 12 is arranged at a position between the rear rotor bearing 39R and the stator 26. The fan 12 rotates by the rotation of the rotor 27. The fan 12 rotates together with the rotor shaft portion 33 by the rotation of the rotor shaft portion 33. The rotation of the fan 12 causes the air in the external space of the housing 2 to flow into the internal space of the housing 2 through the air inlet 19. The air flowing into the internal space of the housing 2 cools the motor 6 by circulating in the internal space of the housing 2. The air circulating in the internal space of the housing 2 rotates with the fan 12 and flows out to the external space of the housing 2 through the exhaust port 20.

[0127] The battery assembly part 13 is arranged at the lower part of the battery holding part 23. The battery assembly part 13 is connected to the battery pack 25. The battery pack 25 is assembled to the battery assembly part 13. In the embodiment, there is one battery assembly part 13. One battery pack 25 is assembled to the battery assembly part 13. The battery pack 25 can be attached to and detached from the battery assembly part 13. The battery pack 25 is assembled to the battery assembly part 13 by being inserted into the battery assembly part 13 from the front of the battery holding part 23. The battery pack 25 is removed from the battery assembly part 13 by being pulled out from the battery assembly part 13 toward the front. The battery pack 25 includes a secondary battery. In the embodiment, the battery pack 25 includes a rechargeable lithium-ion battery. The battery pack 25 can supply power to the impact tool 1 by being assembled to the battery assembly part 13. The motor 6 is driven based on the power supplied from the battery pack 25. The operation display unit 16 operates by the power supplied from the battery pack 25 .

[0128] The rated voltage of the battery pack 25 is greater than 18V. The rated voltage of the battery pack 25 can be 18V, 36V, or 72V.

[0129] The trigger paddle 14 is provided on the grip portion 22. The trigger paddle 14 is operated by the operator to start the motor 6. By operating the trigger paddle 14, the driving and stopping of the motor 6 are switched.

[0130] The forward / reverse switching lever 15 is provided at the upper part of the gripping portion 22. The forward / reverse switching lever 15 is operated by the operator. By operating the forward / reverse switching lever 15, the rotation direction of the motor 6 is switched from one of the forward direction and the reverse direction to the other. By switching the rotation direction of the motor 6, the rotation direction of the spindle 8 is switched.

[0131] The operation display unit 16 is provided in the battery holding unit 23. The operation display unit 16 is provided on the upper surface of the battery holding unit 23 at a position closer to the front side than the grip unit 22. The operation display unit 16 has a plurality of operation buttons 16A. When the operator operates the operation button 16A, the operation mode of the motor 6 is switched.

[0132] The mode switching switch 17 is provided on the upper portion of the trigger lever 14. The mode switching switch 17 is operated by an operator to switch the operation mode of the motor 6.

[0133] The lamp assembly 18 emits illumination light. The lamp assembly 18 illuminates the anvil 10 and the periphery of the anvil 10 with illumination light. The lamp assembly 18 illuminates the front of the anvil 10 with illumination light. In addition, the lamp assembly 18 illuminates the front end tool mounted on the anvil 10 and the periphery of the front end tool with illumination light. In an embodiment, the lamp assembly 18 includes: an annular base member 18A, and a plurality of light emitting elements 18B retained by the base member 18A. The base member 18A is arranged around: the second barrel portion 402 of the hammer case 4. In addition, the lamp assembly 18 has: an annular member 18C for suppressing the base member 18A from falling off from the second barrel portion 402 toward the front.

[0134] In the embodiment, an annular component 61 is arranged between the anvil protrusion 102 and the bearing 46B on the rear side. The annular component 61 is a wheel-shaped component. The annular component 61 is made of metal. As a metal forming the annular component 61, iron can be exemplified. The front surface and the rear surface of the annular component 61 are respectively flat. At least a portion of the rear surface of the annular component 61 is arranged to be opposite to the front surface of the anvil protrusion 102. At least a portion of the front surface of the annular component 61 is in contact with the rear end surface of the bearing 46B on the rear side.

[0135] In the embodiment, a restraining member 62 is provided to engage with the hammer housing 4 and the annular member 61, respectively. The restraining member 62 can restrain the annular member 61 from falling off toward the rear. As the restraining member 62, a snap ring or a C-ring can be exemplified. The restraining member 62 is provided to contact with the annular member 61.

[0136] The hammer case 4 has a support surface 4A facing at least a portion of the front surface of the annular member 61. The support surface 4A of the hammer case 4 and the rear end surface of the rear bearing 46 are substantially arranged in the same plane. At least a portion of the annular member 61 is arranged at a position between the front surface of the anvil protrusion 102 and the support surface 4A of the hammer case 4.

[0137] The annular member 61 can suppress contact between the hammer case 4 and the anvil protrusion 102 .

[0138] At least a portion of the front surface of the annular member 61 contacts the support surface 4A of the hammer case 4. At least a portion of the front surface of the annular member 61 contacts the rear end surface of the rear bearing 46B.

[0139] The front surface outer edge portion, which indicates the front surface outer edge portion of the annular component 61, contacts the support surface 4A of the hammer case 4. The front surface inner edge portion, which indicates the front surface inner edge portion of the annular component 61, can contact the rear end surface of the outer ring of the bearing 46B. The annular component 61 is arranged at a position radially outward from the inner ring of the bearing 46B. The annular component 61 does not contact the inner ring of the bearing 46B.

[0140] The outer edge of the rear surface of the annular member 61 is in contact with the suppression member 62 .

[0141] The inner surface of the first tube portion 401 of the hammer case 4 is provided with a groove 4B into which at least a portion of the suppression member 62 is fitted. By arranging the suppression member 62 in the groove 4B, it is possible to suppress at least the relative positional variation of the hammer case 4 and the suppression member 62 in the axial direction.

[0142] The annular member 61 and the suppressing member 62 prevent the bearing 46 from falling off toward the rear (to the other side in the axial direction).

[0143] The front surface outer edge portion indicating the front surface of the anvil protrusion 102 is inclined toward the radially outer side and toward the rear.

[0144] In the front-rear direction, the suppression member 62 is arranged at a position between the front surface outer edge portion of the anvil protrusion 102 and the rear surface outer edge portion of the annular member 61 .

[0145] [Main axis]

[0146] Figure 5 It is an exploded perspective view showing a part of the striking mechanism 9 according to the embodiment as seen from the front. Figure 6 It is an exploded perspective view showing a part of the striking mechanism 9 according to the embodiment as seen from the rear. Figure 7 It is a side view showing the main shaft 8 according to the embodiment. Figure 8 It is a plan view showing the main shaft 8 according to the embodiment. Fig. 9 It is a plan view showing a part of the main shaft 8 according to the embodiment. Fig.10 It is a perspective view showing a part of the main shaft 8 according to the embodiment. Fig.11 It is a longitudinal sectional view showing the main shaft 8 according to the embodiment. Fig.12 is a cross-sectional view showing the main shaft 8 involved in the embodiment, and is equivalent to Fig.11 Section view along line A-A. Fig.13 It is a side view showing the hammer 47 according to the embodiment. Fig.14 It is a longitudinal sectional view showing the hammer 47 according to the embodiment. Fig.15is a cross-sectional view showing the hammer 47 according to the embodiment, and corresponds to Fig.14 Section view along line B-B. Fig.16 It is a perspective view showing the main shaft 8 according to the embodiment.

[0147] The spindle 8 is arranged at a position closer to the front than the motor 6. The spindle 8 is rotated by the motor 6 about the rotation axis AX. A spindle groove 8D is formed in the spindle 8. The spindle 8 has a flange portion 8A and a spindle shaft portion 8B protruding forward from the flange portion 8A. Two spindle grooves 8D are formed in the spindle shaft portion 8B. The ball 48 is held in the spindle groove 8D. One ball 48 is held in one spindle groove 8D.

[0148] One main shaft groove 8D has a central portion 81 and a pair of end portions 82. In the circumferential direction, the position of the central portion 81 is different from the position of the end portions 82. One end portion 82 is arranged at a position closer to one side in the circumferential direction than the central portion 81, and the other end portion 82 is arranged at a position closer to the other side in the circumferential direction than the central portion 81. The end portions 82 of the main shaft groove 8D are arranged at a position closer to the rear than the central portion 81 of the main shaft groove 8D.

[0149] like Fig.11 , Fig.12 ,as well as Fig.16 As shown, the ball 48 performs circular motion in a virtual plane 91 that is tilted at a predetermined angle θa relative to the rotation axis AX of the main shaft 8 while being held in the main shaft groove 8D. The main shaft groove 8D is formed in an arc shape in the virtual plane 91. The predetermined angle θa is 45 degrees. In addition, the predetermined angle θa may not be 45 degrees, and may be any angle of, for example, 30 degrees or more and 60 degrees or less.

[0150] like Fig.14 as well as Fig.15 As shown, the ball 48 performs circular motion in a virtual plane 91 inclined at a predetermined angle θb with respect to the rotation axis AX of the hammer 47 while being held in the hammer groove 47B. The hammer groove 47B is formed in an arc shape in the virtual plane 91. The predetermined angle θb is 45 degrees.

[0151] That is, in the imaginary plane 91 , the spindle groove 8D and the hammer groove 47B each have an arc shape.

[0152] The spindle groove 8D is formed by a cutting tool 92 such as an end mill. Fig.12 As shown, the cutting tool 92 performs circular motion by moving along an imaginary circle 90 defined by an imaginary plane 91. Fig.12As shown in the figures, the center 90C of the imaginary circle 90 is defined as: a position deviated from the rotation axis AX of the spindle 8. The diameter of the imaginary circle 90 is smaller than the diameter Da of the spindle shaft portion 8B. The center 92C of the cutting tool 92 moves along the imaginary circle 90. The orbit of the center 92C of the cutting tool 92 enters the width of the spindle shaft portion 8B. The orbit of the center 92C of the cutting tool 92 is arc-shaped. At least a part of the orbit of the center 92C of the cutting tool 92 when forming the spindle groove 8D is arranged at: a position closer to the radial inside than the outer peripheral surface 8S of the spindle shaft portion 8B.

[0153] In at least a portion of the formation of the spindle groove 8D, the center 92C of the cutting tool 92 is arranged at a position closer to the radial inside than the outer peripheral surface 8S of the spindle shaft portion 8B. In the formation of the end portion 82 of the spindle groove 8D, the center 92C of the cutting tool 92 is arranged at a position closer to the radial inside than the outer peripheral surface 8S of the spindle shaft portion 8B. In the formation of the central portion 81 of the spindle groove 8D, the center 92C of the cutting tool 92 is arranged at a position closer to the radial outside than the outer peripheral surface 8S of the spindle shaft portion 8B.

[0154] The ball 48 performs circular motion by moving along an imaginary circle 90 defined by an imaginary plane 91. Fig.12 As shown in the figures, the center 90C of the imaginary circle 90 is defined as a position deviated from the rotation axis AX of the spindle 8. The center 48C of the ball 48 moves to a position further outward than the imaginary circle 90. The track of the center 48C of the ball 48 enters the width of the spindle shaft portion 8B. The track of the center 48C of the ball 48 is substantially in the shape of an arc.

[0155] The depth of the spindle groove 8D varies depending on the position in the axial direction (front-rear direction) of the spindle 8. In the embodiment, the depth of the rear portion of the spindle groove 8D is deeper than the depth of the front portion of the spindle groove 8D. That is, the depth of the end portion 82 of the spindle groove 8D is deeper than the depth of the center portion 81 of the spindle groove 8D.

[0156] In at least a portion of the main shaft groove 8D, the center 48C of the ball 48 may be arranged at an inner position of the main shaft groove 8D. In the end portion 82 of the main shaft groove 8D, the center 48C of the ball 48 may be arranged at an inner position of the main shaft groove 8D. In the central portion 81 of the main shaft groove 8D, the center 48C of the ball 48 may be arranged at an outer position of the main shaft groove 8D.

[0157] [Action of impact tool]

[0158] Next, the operation of the impact tool 1 will be described. Fig.17 , Fig.18 ,as well as Fig.19Each of them is a cross-sectional view for explaining the operation of the striking mechanism 9 according to the embodiment.

[0159] When a screw-tightening operation is performed on a work object, a front end tool (driving drill) used in the screw-tightening operation is inserted into the tool hole 10A of the anvil 10. The front end tool inserted into the tool hole 10A is held by the tool holding mechanism 11. After the front end tool is mounted on the anvil 10, the operator, for example, holds the grip 22 with the right hand and pulls the trigger paddle 14. When the trigger paddle 14 is pulled, power is supplied from the battery pack 25 to the motor 6, so that the motor 6 is started and the lamp assembly 18 is lit. The rotor shaft 33 of the rotor 27 is rotated by the start of the motor 6. When the rotor shaft 33 rotates, the rotational force of the rotor shaft 33 is transmitted to the planetary gear 42 via the pinion 41. The planetary gear 42 rotates while revolving around the pinion 41 while meshing with the internal teeth of the internal gear 43. The planetary gear 42 is rotatably supported on the spindle 8 by the pin 42P. The planetary gears 42 revolve around each other, so that the main shaft 8 rotates at a rotation speed lower than the rotation speed of the rotor shaft portion 33 .

[0160] When the spindle 8 rotates while the hammer 47 is in contact with the anvil protrusion 102, the anvil 10 rotates together with the hammer 47 and the spindle 8. The screw tightening operation is performed by the rotation of the anvil 10. The rotational force of the spindle 8 is transmitted to the hammer 47 via the ball 48. When the spindle 8 rotates together with the hammer 47, the ball 48 is arranged at the central portion 81 of the spindle groove 8D.

[0161] When a load torque greater than a predetermined value is applied from the screw to the anvil 10 during the screw tightening operation, the rotation of the anvil 10 and the hammer 47 stops. In the following description, the load torque when the rotation of the anvil 10 and the hammer 47 stops is appropriately referred to as the stop load torque, and the time when the rotation of the anvil 10 and the hammer 47 stops is appropriately referred to as the hammer stop time.

[0162] That is, when the stop load torque acts from the screw to the anvil 10 during the screw tightening operation, the rotation of the anvil 10 and the hammer 47 stops. The spindle 8 is continuously rotated by the motor 6, so when the spindle 8 continues to rotate while the rotation of the hammer 47 stops, the hammer 47 moves backward relative to the spindle 8.

[0163] The hammer 47 moves backward relative to the spindle 8, thereby releasing the contact between the hammer 47 and the anvil protrusion 102. In the following description, the moment when the hammer 47 moves backward relative to the spindle 8 and releases the contact between the hammer 47 and the anvil protrusion 102 is appropriately referred to as the hammer release time.

[0164] like Fig.17 As shown, when the hammer is released, the ball 48 is arranged in the central portion 81 of the main shaft groove 8D.

[0165] When the contact between the hammer 47 and the anvil protrusion 102 is released and the hammer 47 moves backward relative to the spindle 8, the ball 48 moves from the central portion 81 of the spindle groove 8D toward the end portion 82. The hammer 47 moves most backward within the movable range of the hammer 47 in the axial direction relative to the spindle 8. In the following description, the time when the hammer 47 moves most backward relative to the spindle 8 is appropriately referred to as the maximum stroke.

[0166] like Fig.18 As shown, at the maximum stroke, the ball 48 is arranged at the end 82 of the main shaft groove 8D.

[0167] The hammer 47 moved to the rear is moved forward while rotating due to the forward force of the first coil spring 49 and the second coil spring 50. When the hammer 47 moves forward relative to the spindle 8, the ball 48 moves from the end 82 of the spindle groove 8D toward the center 81. In the following description, the moment when the hammer 47 moves forward while rotating and is about to strike the anvil 10 is appropriately referred to as the striking start time. Fig.17 As shown, at the start of striking, the ball 48 is arranged at the center portion 81 of the spindle groove 8D. The time when the hammer 47 strikes the anvil 10 in the rotational direction is appropriately referred to as the striking time.

[0168] The hammer 47 moves forward while rotating, and the anvil 10 is struck in the rotation direction by the hammer 47. As a result, the anvil 10 rotates around the rotation axis AX at a high torque. As a result, the screw is tightened to the work object at a high torque.

[0169] Fig.19 The main shaft 8, the ball 48, and the hammer 47 during striking are shown.

[0170] In the following description, the torque acting on the anvil 10 when the hammer 47 starts to strike the anvil 10 is appropriately referred to as the striking start torque. The striking start torque is equal to the above-mentioned stop load torque. That is, the striking start torque is equal to the load torque acting on the anvil 10 from the screw when the rotation of the anvil 10 and the hammer 47 stops during the screw tightening operation.

[0171] [Effect]

[0172] Hereinafter, the effects of the impact tool 1 according to the embodiment will be described in comparison with a spindle 800 according to a conventional example. In the following description, the spindle 8 according to the embodiment is appropriately referred to as an example, and the spindle 800 according to the conventional example is appropriately referred to as a comparative example.

[0173] Fig. 20 1 is a top view showing a portion of a spindle 800 according to a comparative example. A spindle groove 800D is formed in a spindle shaft portion 800B of the spindle 800 according to the comparative example. The spindle groove 800D is a spindle groove commonly used in existing spindles and is V-shaped. The depth of the center portion of the spindle groove 800D is substantially equal to the depth of the end portion.

[0174] Fig.21 The diagrams are for explaining the relationship between the spindles 8 and 800 and the balls 48 according to the embodiment and the comparative example, respectively.

[0175] like Fig.21 As shown, in the spindle 8 involved in the embodiment, at the end 82 of the spindle groove 8D, the center 48C of the ball 48 is arranged at the inner position of the spindle groove 8D. The depth of the end 82 of the spindle groove 8D is deeper than the depth of the central portion 81 of the spindle groove 8D. Accordingly, when the ball 48 is arranged at the end 82, the ball 48 sinks to the inner position of the spindle groove 8D compared with the case where the ball 48 is arranged at the central portion 81. That is, when the ball 48 is arranged at the end 82 of the spindle groove 8D, in the radial direction, the distance between the rotation axis AX and the center 48C is shorter than the distance between the rotation axis AX and the outer peripheral surface 8S of the spindle shaft portion 8B. When the ball 48 is arranged at the end 82 of the spindle groove 8D, the center 48C is arranged at a position closer to the radial inside than the outer peripheral surface 8S.

[0176] like Fig.21 As shown in FIG. 1 , in the spindle 800 of the comparative example, the depth of the central portion of the spindle groove 800D is substantially equal to the depth of the end portion. Accordingly, when the ball 48 is arranged at the end portion 820 of the spindle groove 800D, the ball 48 is arranged at the radially outer position compared to the case where the ball 48 is arranged at the end portion 82 of the spindle groove 8D of the embodiment.

[0177] Fig. 22 The diagrams are for explaining the force received by the ball 48 from the spindle 8 or 800 according to each of the embodiment and the comparative example.

[0178] like Fig. 22 As shown in FIG. 1 , in the spindle 8 of the embodiment, when the ball 48 is arranged at the end 82 of the spindle groove 8D, the ball 48 sinks to the radial inner side, so that at the maximum stroke, the component of the rotation direction of the force acting between the spindle 8 and the ball 48 becomes larger. That is, as shown by the arrow Ve, the force acting from the spindle 8 to the ball 48 acts exclusively in the rotation direction. Fig.18 As explained above, the moment when the ball 48 is arranged at the end 82 of the main shaft groove 8D is the time of the maximum stroke. At the maximum stroke, the ball 48 is subjected to the force in the rotational direction only, so the hammer 47 can move forward while rotating at a relatively high rotational speed. The axial component of the force acting on the ball 48 from the main shaft 8 is a useless force. The axial component of the force acting on the ball 48 from the main shaft 8 is small, while the component in the rotational direction is large, so the hammer 47 can move forward while rotating at a relatively high rotational speed.

[0179] like Fig. 22 As shown, in the spindle 800 according to the comparative example, when the ball 48 is arranged at the end 820 of the spindle groove 800D, as shown by the arrow Vc, the axial component of the force acting on the ball 48 from the spindle 800 is large. In this case, it is difficult to increase the rotation speed of the hammer 47.

[0180] Fig.23 1 is a diagram for explaining the striking start torque involved in each of the embodiment and the comparative example. Fig.23 In the graph shown, the horizontal axis represents the time elapsed from the start of the screw tightening operation. The vertical axis represents the striking start torque acting on the anvil 10. As described above, the striking start torque is the torque acting on the anvil 10 when the hammer 47 starts to strike the anvil 10. The striking start torque is equal to the stop load torque acting from the screw on the anvil 10 when the rotation of the anvil 10 and the hammer 47 stops during the screw tightening operation.

[0181] like Fig.23 As shown, in the comparative example, the striking start torque is about 1350 N·mm. In the embodiment, the striking start torque is less than 1100 N·mm. Fig.23 In the example shown, the striking start torque according to the embodiment is approximately 1000 N·mm or less.

[0182] When the torque at the start of the strike is small, the occurrence of the slippage phenomenon in which the front end tool (driving drill bit) disengages from the cross groove of the head of the screw during the screw tightening operation can be suppressed. According to the understanding of the inventors, when the torque at the start of the strike is small, the timing of the start of the strike of the anvil 10 is advanced. That is, when the torque at the start of the strike is small, the amount of screw rotation from the start of screw tightening to the start of the strike is reduced. When the amount of screw rotation from the start of screw tightening to the start of the strike is reduced, the occurrence of the slippage phenomenon can be suppressed.

[0183] Fig.24 It is a diagram showing the tightening speed, average current and average voltage involved in each of the embodiments and comparative examples. The tightening speed refers to: the operating speed of one screw tightening operation. The larger the value, the higher the tightening speed, which means: the shorter the time required from the start to the end of one screw tightening operation. The average current is: the average value of the current consumed by the motor 6 in one screw tightening operation. The average voltage is: the average value of the voltage input to the motor 6 in one screw tightening operation. The smaller the average current and the average voltage, the less power consumption of the motor 6.

[0184] Using the impact tools according to the embodiment and the comparative example, a coarse screw with a length of 90 mm, a coarse screw with a length of 120 mm, and a metal screw with a length of 150 mm were tightened.

[0185] like Fig.24 As shown, the tightening speed involved in the embodiment is higher than the tightening speed involved in the comparative example. Fig.21 As described above, in the embodiment, the hammer 47 rotates at a high rotation speed, so it is possible to strike the anvil 10 with a large striking force. Since the anvil 10 can be struck with a large striking force, the screw tightening operation can be completed in a short time.

[0186] Fig.25 It is a diagram showing the direction in which the load is transmitted from the ball 48 to the weight 47 according to each of the embodiment and the comparative example. Fig.25 The moment when the hammer 47 moves to the rearmost position relative to the spindle 8, 800, that is, the state at the maximum stroke is shown. A direction passing through the contact point 47F between the ball 48 and the inner surface of the hammer groove 47B and parallel to the tangent of the circle centered on the rotation axis AX of the spindle 8 is defined as a tangent vector Vr. A direction in which the load is transmitted from the ball 48 to the contact point 47F between the ball 48 and the hammer 47 is defined as a load vector Vp. In the embodiment, the angle α formed by the tangent vector Vr and the load vector Vp at the maximum stroke is 50 degrees or less. Fig.25The angle α formed by the tangent vector Vr and the load vector Vp at the maximum stroke in the illustrated embodiment is 45.1 degrees. On the other hand, the angle α formed by the tangent vector Vr and the load vector Vp at the maximum stroke in the comparative example is 56.3 degrees.

[0187] The angle α formed by the tangent vector Vr and the load vector Vp at the start of the strike in the embodiment is 43.1 degrees, while the angle α formed by the tangent vector Vr and the load vector Vp at the start of the strike in the comparative example is 57.3 degrees.

[0188] In addition, the angle α formed by the tangent vector Vr and the load vector Vp at the time of the impact in the embodiment is 58.6 degrees, and the angle α formed by the tangent vector Vr and the load vector Vp at the time of the impact in the comparative example is 85.7 degrees.

[0189] As described above, the end 82 of the main shaft groove 8D is arranged at a position further rearward than the central portion 81 of the main shaft groove 8D. When the hammer 47 moves rearward relative to the main shaft 8, the ball 48 moves toward the end 82 of the main shaft groove 8D. In the embodiment, the angle α formed by the tangent vector Vr and the load vector Vp changes based on the position of the ball 48 in the main shaft groove 8D (hammer groove 47B). In the embodiment, the closer the ball 48 is to the end of the main shaft groove 8D, the smaller the angle α formed by the tangent vector Vr and the load vector Vp.

[0190] The smaller the angle α formed by the tangent vector Vr and the load vector Vp, the more the force acting from the main shaft 8 on the ball 48 acts exclusively in the rotation direction. In the embodiment, the axial component of the force acting from the main shaft 8 on the ball 48 is small and the rotational component is large, so the hammer 47 can move forward while rotating at a high rotation speed.

[0191] As described above, in the embodiment, the impact tool 1 includes: the motor 6; the spindle 8, which is arranged at a position closer to the front than the motor 6 and rotated by the motor 6; the spindle groove 8D formed in the spindle 8; the ball 48, which is held in the spindle groove 8D; the hammer 47, which is supported by the spindle 8 via the ball 48; the first coil spring 49 and the second coil spring 50, which urge the hammer 47 forward; and the anvil 10, which is struck in the rotation direction by the hammer 47. The depth of the spindle groove 8D varies depending on the position of the spindle 8 in the axial direction.

[0192] As described above, when the stop load torque acts on the anvil 10 from the screw during the screw tightening operation, the rotation of the anvil 10 and the hammer 47 stops. Since the spindle 8 is continuously rotated by the motor 6, when the spindle 8 continues to rotate while the rotation of the hammer 47 is stopped, the hammer 47 moves backward relative to the spindle 8. After the hammer 47 moves backward, the hammer 47 moves forward while rotating due to the urging force of the first coil spring 49 and the second coil spring 50. As the hammer 47 moves forward while rotating, the anvil 10 is struck by the hammer 47 in the rotation direction.

[0193] In the above configuration, the depth of the spindle groove 8D varies depending on the axial position of the spindle 8, so the component in the rotational direction of the force acting between the spindle 8 and the ball 48 becomes larger. As a result, the rotation speed of the hammer 47 when the hammer 47 moves forward while rotating is increased. Since the rotation speed of the hammer 47 is increased, the hammer 47 can strike the anvil 10 with a greater striking force.

[0194] In addition, the component of the rotation direction of the force acting between the main shaft 8 and the ball 48 becomes larger and the component of the axial direction becomes smaller, so even if the spring coefficients of the first coil spring 49 and the second coil spring 50 are small, the first coil spring 49 and the second coil spring 50 can urge the hammer 47 forward. That is, even if the force of the first coil spring 49 and the second coil spring 50 is small, the hammer 47 can move forward while rotating by the force of the first coil spring 49 and the second coil spring 50. By using the first coil spring 49 and the second coil spring 50 with small force, the timing of the hammer 47 starting to strike the anvil 10 can be advanced. That is, the period from the moment when the hammer 47 stops rotating to the moment when the hammer 47 strikes the anvil 10 is shortened.

[0195] In the screw tightening operation, the anvil 10 is rotated in a state where the tip tool mounted on the anvil 10 is inserted into the cross groove formed in the head of the screw. In the case where the hammer 47 starts striking the anvil 10 late, that is, when the screw rotation amount from the start of screw tightening to the time when the hammer 47 strikes the anvil 10 is large, the possibility of the tip tool slipping out of the cross groove becomes high. In the above-mentioned structure, the hammer 47 starts striking the anvil 10 early, so the occurrence of the slipping phenomenon can be suppressed.

[0196] In the embodiment, the end 82 of the main shaft groove 8D is arranged at a position further rearward than the central portion 81 of the main shaft groove 8D. When the hammer 47 moves rearward relative to the main shaft 8, the ball 48 moves toward the end 82 of the main shaft groove 8D. At the end 82 of the main shaft groove 8D, the center 48C of the ball 48 is arranged at the inner side of the main shaft groove 8D.

[0197] When the hammer 47 moves backward relative to the spindle 8, the ball 48 moves from the central portion 81 to the end portion 82 of the spindle groove 8D. When the hammer 47 moves forward relative to the spindle 8 by the urging force of the first coil spring 49 and the second coil spring 50, the ball 48 moves from the end portion 82 to the central portion 81 of the spindle groove 8D. In the above-mentioned structure, the center 48C of the ball 48 sinks to the inner side position of the spindle groove 8D at the end portion 82 of the spindle groove 8D, so the rotation speed of the hammer 47 when the hammer 47 moves forward while rotating is increased. Since the rotation speed of the hammer 47 is increased, the hammer 47 can strike the anvil 10 with a large striking force.

[0198] In the embodiment, in the central portion 81 of the main shaft groove 8D, the center 48C of the ball 48 is arranged at a position outside the main shaft groove 8D.

[0199] When the hammer 47 strikes the anvil 10, the ball 48 moves from the end 82 of the main shaft groove 8D toward the central portion 81. In the above configuration, the center 48C of the ball 48 is arranged at the outer side of the main shaft groove 8D in the central portion 81 of the main shaft groove 8D, so the rotation speed of the hammer 47 is increased at the moment when the hammer 47 strikes the anvil 10. Since the rotation speed of the hammer 47 is increased, the hammer 47 can strike the anvil 10 with a greater striking force.

[0200] In the embodiment, the spindle 8 has a flange portion supporting the rear ends of the first coil spring 49 and the second coil spring 50, and a spindle 8 shaft portion protruding forward from the flange portion. A spindle groove 8D is formed in the spindle 8 shaft portion. The track of the center 48C of the ball 48 enters the width of the spindle 8 shaft portion.

[0201] In the above-described configuration, the moving range of the ball 48 is small, so that the rotation speed of the hammer 47 can be increased while suppressing an increase in the size of the impact tool 1 .

[0202] In an embodiment, the track is in the shape of an arc.

[0203] In the above structure, the ball 48 performs a circular motion along an imaginary circle with a small radius. As a result, the hammer 47 can smoothly rotate while moving in the axial direction. The sliding resistance of the hammer 47 is reduced, so the rotation speed of the hammer 47 is increased. As a result, the hammer 47 can strike the anvil 10 with a large striking force.

[0204] In the embodiment, the balls 48 can perform circular motion in a virtual plane that is inclined at a predetermined angle with respect to the rotation axis of the spindle 8 .

[0205] In the above configuration, the sliding resistance of the hammer 47 is reduced, so the rotation speed of the hammer 47 is increased. As a result, the hammer 47 can strike the anvil 10 with a large striking force.

[0206] In the embodiment, the ball 48 performs a circular motion such that the center 48C of the ball 48 moves along a virtual circle defined by the virtual plane. The center 90C of the virtual circle is defined at a position offset from the rotation axis AX of the spindle 8 .

[0207] In the above-described configuration, the hammer 47 can strike the anvil 10 with a large striking force.

[0208] In the embodiment, the spindle 8 has a flange portion supporting the rear ends of the first coil spring 49 and the second coil spring 50, and a spindle 8 shaft portion protruding forward from the flange portion. The spindle groove 8D is formed in the spindle 8 shaft portion. The diameter of the imaginary circle is smaller than the diameter of the spindle 8 shaft portion.

[0209] In the above-described configuration, the moving range of the ball 48 is small, so that the rotation speed of the hammer 47 can be increased while suppressing an increase in the size of the impact tool 1 .

[0210] In the embodiment, the striking start torque, which indicates the torque acting on the anvil 10 when the hammer 47 starts striking the anvil 10 , is 1100 N·mm or less.

[0211] In the above configuration, the striking start torque is small, so the timing of the hammer 47 striking the anvil 10 is advanced. That is, the screw rotation amount from the start of screw tightening to the striking of the anvil 10 by the hammer 47 is reduced.

[0212] When the hammer 47 starts striking the anvil 10 late, that is, when the screw has rotated a lot from the start of screw tightening to the striking position where the hammer 47 strikes the anvil 10, the possibility of the tip tool slipping out of the cross groove becomes high. In the above configuration, the hammer 47 starts striking the anvil 10 early, so the occurrence of the slipping phenomenon can be suppressed.

[0213] In the embodiment, the impact tool 1 includes a battery mounting portion 13 for mounting a battery pack 25. The rated voltage of the battery pack 25 is 18V or more.

[0214] In the above-described configuration, the rated voltage of the battery pack 25 is 18 V or more, so that the output of the impact tool 1 can be increased.

[0215] In the embodiment, the depth of the spindle groove 8D is different depending on the position in the axial direction of the spindle 8 .

[0216] In the above-mentioned configuration, the occurrence of the slip phenomenon can be suppressed.

[0217] In the embodiment, the depth of the rear portion of the main shaft groove 8D is deeper than the depth of the front portion of the main shaft groove 8D. The depth of the end portion 82 of the main shaft groove 8D is deeper than the depth of the center portion 81 of the main shaft groove 8D.

[0218] In the above configuration, the center 48C of the ball 48 can sink into the inner position of the spindle groove 8D, so the component of the rotation direction of the force acting between the spindle 8 and the ball 48 becomes larger. According to this, the rotation speed of the hammer 47 when the hammer 47 moves forward while rotating is increased. Since the rotation speed of the hammer 47 is increased, the hammer 47 can strike the anvil 10 with a larger striking force.

[0219] [Other embodiments]

[0220] In the above embodiment, the width of the end portion 82 of the main shaft groove 8D may be greater than the width of the central portion 81 of the main shaft groove 8D. When the width of the end portion 82 is greater than the width of the central portion 81, the component of the rotational direction of the force acting between the main shaft 8 and the ball 48 becomes larger at the maximum stroke.

[0221] In the above embodiment, the impact tool 1 is an impact driver. The impact tool 1 may also be an impact wrench. In the above embodiment, the impact tool 1 may also be an angle impact tool.

[0222] In the above embodiment, the power source of the impact tool 1 may not be the battery pack 25 but may be a commercial power source (AC power source). The commercial power source can input a voltage of 18V or more to the motor 6 .

Claims

1. An impact tool, characterized in that: The impact tool has: motor; a main shaft which is rotated by the motor; a spindle groove formed in the spindle; a ball held in the spindle groove; a hammer supported on the spindle by means of the ball; a spring that applies force to the hammer forward; as well as an anvil, which is struck in a rotational direction by the hammer, The depth of the main shaft groove varies depending on the position in the axial direction of the main shaft.

2. The impact tool according to claim 1, characterized in that The depth of the rear portion of the main shaft groove is deeper than the depth of the front portion of the main shaft groove.

3. The impact tool according to claim 2, characterized in that The depth of the end portion of the main shaft groove is deeper than the depth of the center portion of the main shaft groove.

4. An impact tool, characterized in that: The impact tool has: motor; a main shaft which is rotated by the motor; a spindle groove formed in the spindle; a ball held in the spindle groove; a hammer supported on the spindle by means of the ball; a spring that applies force to the hammer forward; as well as anvil, which is struck in a rotational direction by the hammer The spindle groove is formed by a cutting tool, At least a portion of a trajectory of the center of the cutting tool when the spindle groove is formed is arranged radially inward of an outer peripheral surface of the spindle.

5. The impact tool according to claim 4, characterized in that The end of the main shaft groove is arranged at a position further rearward than the center of the main shaft groove. When the hammer moves backward relative to the spindle, the ball moves toward the end of the spindle groove. At an end portion of the spindle groove, the center of the cutting tool is arranged radially inward of an outer peripheral surface of the spindle.

6. The impact tool according to claim 5, characterized in that In the central portion of the spindle groove, the center of the cutting tool is arranged radially outward relative to the outer peripheral surface of the spindle.

7. The impact tool according to claim 4, characterized in that The main shaft groove is in an arc shape.

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