Work equipment

Abstract

To provide a work machine with a highly reliable tool holding device. [Solution] In the tool holding device of the work machine, the elastic member 50 is composed of an annular spring in which a plate material extending from one end 50a to the other end 50b is wound in a substantially annular shape. The elastic member 50 is configured such that when the metal ball 39 is moved radially outward, the other end 50b overlaps radially outward than the one end 50a. When the elastic member 50 is attached to the outer circumference of the anvil 33, the plate material is configured to overlap twice radially throughout the circumferential direction.

Description

Technical Field

[0001] The present invention relates to a working machine provided with a tool holding device for holding bits.

Background Art

[0002] Patent Document 1 discloses an elastic member that elastically deforms when an engaging member moves radially outward in a tool holding device of a working machine. Patent Document 2 discloses an elastic member that elastically deforms when an engaging member moves radially outward in a tool holding device of a working machine.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] Since the elastic member of Patent Document 1 is configured by connecting coil springs in a ring shape, the coil springs are likely to plastically deform, and there is room for improvement in terms of reliability. Since the elastic member of Patent Document 2 has a notch in part in the circumferential direction, there is a risk that the engaging member will enter the notch, causing the elastic member to plastically deform or hindering the movement of the engaging member, and there is room for improvement in terms of reliability.

[0005] An object of the present invention is to provide a working machine having a highly reliable tool holding device.

Means for Solving the Problems

[0006] One aspect of the present invention is a motor, a tool holding device rotated by the motor, A work machine having, The tool holding device is A tool holder extending in the front-rear direction, having an insertion hole into which a bit can be inserted from front to rear, and an elongated hole for supporting an engaging member that can engage with the bit so as to be movable between a front position and a rear position, A substantially cylindrical operating member that is movable between a forward position and a rearward position on the outer circumference of the tool holder, the operating member having a first restricting portion that is located outside the engaging member in the radial direction of the tool holder and restricts the outward movement of the engaging member in the radial direction when the operating member is in the rearward position and the engaging member is in the forward position, When the operating member is in the rear position and the engaging member is in the rear position, a substantially annular elastic member is located outside the engaging member in the radial direction, and the elastic member deforms elastically when the engaging member in the rear position moves outward in the radial direction, It has, The elastic member has an annular portion that extends substantially in an annular shape on the outer circumference of the tool holder, The annular portion is composed of an annular spring formed by winding a plate material extending from one end to the other in a substantially annular shape, and the annular portion is attached to the outer circumference of the tool holder, and is configured such that when the engaging member is moved outward in the radial direction, the other end overlaps radially outward from the one end. This is a work machine characterized by the following features.

[0007] The present invention may also be described as "electric work machine," "power tool," "electric equipment," etc., and such descriptions are also valid embodiments of the present invention. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a work machine having a highly reliable tool holding device. [Brief explanation of the drawing]

[0009] [Figure 1] A side cross-sectional view of the work machine 1 according to Embodiment 1. [Figure 2] Exploded perspective view of the tool holding device of the work machine 1. [Figure 3] Side cross-sectional view of the tool holding device. [Figure 4] Side cross-sectional view showing the process of inserting and holding the bit 70 in the tool holding device. [Figure 5] Side cross-sectional view showing that the removal of the bit 70 from the tool holding device is restricted. [Figure 6] Side cross-sectional view showing the process of removing the bit 70 from the tool holding device. [Figure 7] View of the elastic member 50 of the tool holding device as seen from the front. [Figure 8] Cross-sectional view showing the state in which the metal ball 39 has moved backward from the state of FIG. 3. [Figure 9] A - A cross-sectional view of FIG. 7. [Figure 10] Cross-sectional view showing the state in which the metal ball 39 has moved to the outside in the radial direction of the anvil 33 in FIG. 9. [Figure 11] Cross-sectional view according to the comparative example, showing a configuration in which the elastic member 50 in FIG. 9 is replaced with an elastic member 850. [Figure 12] Cross-sectional view showing the state in which the metal ball 39 has moved to the outside in the radial direction of the anvil 33 in FIG. 11. [Figure 13] Cross-sectional view according to Embodiment 2, showing a configuration in which the elastic member 50 in FIG. 9 is replaced with an elastic member 250. [Figure 14] Cross-sectional view showing the state in which the metal ball 39 has moved to the outside in the radial direction of the anvil 33 in FIG. 13. [Figure 15] Cross-sectional view according to Embodiment 3, showing a configuration in which the elastic member 50 in FIG. 9 is replaced with an elastic member 350. [Figure 16] Cross-sectional view showing the state in which the metal ball 39 has moved to the outside in the radial direction of the anvil 33 in FIG. 15.

Mode for Carrying Out the Invention

[0010] [Embodiment 1]<​​Figure 1 is a side cross-sectional view of the work implement 1 according to Embodiment 1. The work implement 1 is a cordless type impact driver that operates on the power of the battery pack 17. Figure 1 defines the front-rear and up-down directions of the work implement 1.

[0011] The work machine 1 comprises a housing 10, a tail cover 14, a trigger switch 15 as a first operating unit, a forward / reverse switch 16, a hammer case 18, an illumination LED 19 as a light, a motor 20, a reduction mechanism 28, a spindle 29, a hammer spring 31, a hammer 32, an anvil 33, a fan 34, a control board 35, a sensor / inverter board 36, a guide sleeve 40, and an operation panel 85.

[0012] The housing 10 is formed by fixing and integrating two separate resin molded bodies, for example, left and right, using screws or the like. The housing 10 includes a motor housing 11, a handle 12, and a battery pack mounting section 13.

[0013] The motor housing 11 is a cylindrical section with its central axis substantially parallel to the front-rear direction. The handle section 12 has its upper end connected to the middle section of the motor housing 11 in the front-rear direction and extends downward from that middle section. The battery pack mounting section 13 is provided at the lower end of the handle section 12 and is used to detachably mount the battery pack 17. The tail cover 14 is made of, for example, a molded resin body. The tail cover 14 is connected and fixed to the rear end of the motor housing 11 by screws or the like, and covers the rear opening of the motor housing 11.

[0014] The trigger switch 15 is supported at the front of the upper end of the handle portion 12. The trigger switch 15 is the motor drive operation unit (main operation unit) for the user to switch the motor 20 on and off. The greater the amount the trigger switch 15 is operated, the higher the rotational speed of the motor 20.

[0015] The forward / reverse selector switch 16 is supported by the housing 10 above and near the trigger switch 15. The forward / reverse selector switch 16 is a rotation direction switching operation unit for the user to switch between forward and reverse rotation of the motor 20. Forward rotation is rotation in the direction of clockwise (rightward) when viewed from the rear. Reverse rotation is rotation in the direction of counterclockwise (leftward) when viewed from the rear.

[0016] The hammer case 18 is made of a metal such as aluminum, is held in the motor housing 11, and extends forward from the motor housing 11. Multiple illumination LEDs 19 are provided around the front end of the hammer case 18, for example, at equal angular intervals, to illuminate the working area of ​​the work machine 1.

[0017] The motor 20 is housed and held in the motor housing 11. The motor 20 is an inner rotor type brushless motor and has a motor shaft 21 parallel to the front-rear direction. The reduction mechanism 28, spindle 29, hammer spring 31, hammer 32, and anvil 33 are housed and held in the hammer case 18.

[0018] The reduction mechanism 28 reduces the rotation of the motor 20 and transmits it to the spindle 29. The spindle 29 drives the hammer 32. The hammer spring 31 biases the hammer 32 forward. The hammer 32 cam-engages with the spindle 29 and, driven by the spindle 29, rotates and strikes the anvil 33. The hammer spring 31, hammer 32, and anvil 33 constitute a rotary striking mechanism and form the output section of the work machine 1. The motor 20, reduction mechanism 28, spindle 29, and rotary striking mechanism correspond to the work section that performs work using power.

[0019] The anvil 33 is rotatably supported on the hammer case 18 via a bearing 49. The anvil 33 has a bit insertion hole 37 that opens forward. The bit insertion hole 37 holds a tip tool such as the bit 70 shown in Figures 4 to 6. The guide sleeve 40 is a component operated by the user when removing the tip tool such as the bit 70 from the bit insertion hole 37. As will be described in detail later, the tip tool such as the bit 70 can be removed forward from the bit insertion hole 37 by pulling the guide sleeve 40 forward.

[0020] The fan 34 is installed inside the motor housing 11. The fan 34 is attached to the motor shaft 21 at the rear of the motor 20 excluding the motor shaft 21 (hereinafter referred to as the "motor body"), and rotates integrally with the motor shaft 21, generating cooling air to cool the motor 20 and other components.

[0021] The control board 35 is located inside the battery pack mounting section 13. The control board 35 is equipped with a control unit (microcontroller) and the like that controls the drive of the motor 20. The control board 35 is housed and held in the board case 80.

[0022] The sensor / inverter board 36 is located in front of the motor body within the motor housing 11. The sensor / inverter board 36 is equipped with a magnetic sensor such as a Hall IC for detecting the rotational position of the motor 20, and a switching element for supplying drive current to the motor 20.

[0023] The control panel 85 faces the front upper surface of the battery pack mounting section 13. The user can switch the drive mode (operating mode) and lighting mode of the work machine 1 using the control panel 85. The control panel 85 has the functions of a drive mode selection control unit, a drive mode display unit, and a lighting mode selection control unit.

[0024] (Configuration of the tool holding device) Figure 2 is an exploded perspective view of the tool holder of the work machine 1. Figure 3 is a side cross-sectional view of the tool holder. The work machine 1 is characterized by the structure of the tool holder that holds the tip tool such as the bit 70.

[0025] As shown in Figures 2 and 3, the tool holding device of the work machine 1 includes an anvil 33 as a tool holder, a metal ball 39 as an engaging member, a guide sleeve 40 as an operating member, a guide spring 43 as a biasing member, a washer 44 as a spring receiving member, a retaining ring 45 as a retaining part, and an elastic member 50.

[0026] The anvil 33 is a metal body extending in the front-rear direction and is configured to allow the bit 70 to be inserted into the bit insertion hole 37 from front to rear. The anvil 33 is rotatably supported on the hammer case 18 by a bearing 49, as shown in Figure 1.

[0027] As shown in Figure 2, the anvil 33 has a shaft portion 56 and a blade portion 57. The shaft portion 56 has a bit insertion hole 37 inside and is a cylindrical portion with a central axis parallel to the front-rear direction. Hereinafter, the radial direction of the shaft portion 56 will be referred to as the "radial direction" and the circumferential direction of the shaft portion 56 will be referred to as the "circumferential direction". The shaft portion 56 has a large diameter portion 56a and a small diameter portion 56b. The large diameter portion 56a is connected to the rear of the small diameter portion 56b. The blade portion 57 spreads radially at the rear of the shaft portion 56. For example, three blade portions 57 are provided in the circumferential direction at equal angular intervals. The blade portion 57 is struck by the hammer 32.

[0028] The anvil 33 has elongated holes 38 at the upper and lower parts of the side circumference of the bit insertion hole 37 in the small diameter portion 56b. The elongated holes 38 support (house) a metal ball 39 that can engage with the groove portion 72 (Figure 4) of the bit 70 so that it can move between a forward position and a backward position. The groove portion 72 has, for example, an arc-shaped cross-section and encircles the outer surface of the bit 70.

[0029] The anvil 33 has an elastic member mounting groove 59 (Figure 2) and an anvil projection 60 as a second restricting portion on the rear outer circumferential surface of the small diameter portion 56b.

[0030] The elastic member mounting groove 59 is positioned to overlap with the rear of the elongated hole 38 in the front-rear direction, and encircles the outer circumference of the anvil 33, excluding the portion where the elongated hole 38 is located. The elastic member mounting groove 59 is adjacent to the rear of the anvil projection 60.

[0031] The anvil projection 60 is located between the elastic member 50 and the convex portion 42 of the guide sleeve 40 in the front-rear direction. The anvil projection 60 is located in a position that overlaps with the middle portion of the elongated hole 38 in the front-rear direction, that is, between the rear end and the front end of the elongated hole 38 in the front-rear direction, extending radially outward from the outer circumference of the anvil 33 and encircling the outer circumference of the anvil 33 except for the portion where the elongated hole 38 is located.

[0032] The anvil projection 60 constitutes the front wall portion of the elastic member mounting groove 59. The anvil projection 60 is configured to protrude radially outward from the elastic member 50 provided in the elastic member mounting groove 59. The elongated hole 38 extends forward from the anvil projection 60. The anvil projection 60 has a second inclined surface 61 (Figure 3) on its front surface that recedes as it moves radially outward. The second inclined surface 61 of the anvil projection 60 comes into contact (preferably in surface contact) with the first inclined surface 46 provided at the rear of the convex portion 42 of the guide sleeve 40, thereby restricting the rearward movement of the guide sleeve 40 and determining the rearward position (the position in its most retracted state) of the guide sleeve 40.

[0033] The elastic member 50 constitutes an annular portion that extends in a ring shape on the outer circumference of the anvil 33. The elastic member 50 is attached to the elastic member mounting groove 59 shown in Figure 2 and is coaxial with the anvil 33. The elastic member 50 is a metal elastic ring that can expand and contract elastically. The front-to-back lengths of the elastic member 50 and the elastic member mounting groove 59 are approximately equal to each other.

[0034] As shown in Figures 4(C) and (D), the elastic member 50 is located radially outside the metal ball 39 when the guide sleeve 40 is in the rear position and the metal ball 39 is in the rear position, and elastically deforms when the metal ball 39, which is in the rear position, moves radially outward (Figures 4(C)→(D)).

[0035] As shown in Figure 3, when the metal ball 39 is in its innermost position in the radial direction, it protrudes by a predetermined length from the inner opening of the elongated hole 38 and partially extends inside the bit insertion hole 37.

[0036] The guide sleeve 40 is made of metal and is formed in a substantially cylindrical shape. It is attached to the anvil 33 so as to cover the outer circumference of the front end of the anvil 33. The guide sleeve 40 is movable between a forward position and a rearward position on the outer circumference of the anvil 33. As shown in Figure 3, the retracted position of the guide sleeve 40 is determined when the first inclined surface 46 at the rear of the convex portion 42 of the guide sleeve 40 comes into contact with (engages with) the second inclined surface 61 on the front of the anvil projection 60.

[0037] The guide sleeve 40 has a recess 41 and a protrusion 42 as a first restricting portion.

[0038] The recess 41 is a portion recessed from the convex portion 42 and extends around the inner rear surface of the guide sleeve 40 in the circumferential direction. The recess 41 constitutes a space that allows the elastic member 50 to expand in diameter. As shown in Figure 3, when the guide sleeve 40 is in the rear position, the recess 41 faces the rear of the elongated hole 38. As shown in Figures 6(B) and (C), when the guide sleeve 40 is in the front position, the recess 41 faces the front of the elongated hole 38.

[0039] The convex portion 42 is a projection that protrudes radially inward on the front side of the recess 41 and extends around the circumference. As shown in Figure 3, when the guide sleeve 40 is in the rear position and the metal ball 39 is in the front position, the convex portion 42 faces the elongated hole 38 and is located radially outside the metal ball 39, restricting the radial outward movement of the metal ball 39. In the state shown in Figure 3, the center of gravity of the metal ball 39 and the area where the convex portion 42 exists overlap in the front-rear direction. As shown in Figures 6(B) and (C), when the guide sleeve 40 is in the front position, most of the convex portion 42 is in front of the elongated hole 38, allowing radial outward movement of the metal ball 39.

[0040] The guide spring 43 is a compression coil spring whose central axis direction is parallel to the central axis direction of the anvil 33, i.e., the front-rear direction. The guide spring 43 biases the guide sleeve 40 rearward relative to the anvil 33, i.e., biases the guide sleeve 40 toward the rearward position. The guide spring 43 is provided between the inner circumferential surface of the guide sleeve 40 and the outer circumferential surface of the anvil 33. The rear end of the guide spring 43 is supported by a protrusion 42 of the guide sleeve 40. The front end of the guide spring 43 is supported by a washer 44 provided at the front end of the anvil 33. The guide spring 43 is compressed in the front-rear direction by the protrusion 42 and the washer 44. The washer 44 is located in front of the guide spring 43 and its forward movement relative to the anvil 33 is restricted by a retaining ring 45 provided at the front end of the anvil 33. As a result, the guide spring 43 and washer 44 do not fall forward from the anvil 33.

[0041] Figures 4(A) to 4(F) show the process of inserting and holding the bit 70 in the tool holder.

[0042] As the bit 70 is inserted into the bit insertion hole 37, the metal ball 39 is pushed by the inclined (tapered) portion of the rear end of the bit 70 and moves toward the rear of the elongated hole 38 as shown in Figures 4(A) to (D). At the same time, as shown in Figures 4(B) to (D), it moves radially outward while elastically deforming the elastic member 50, resulting in a position that does not hinder further insertion of the bit 70, as shown in Figure 4(D).

[0043] As the bit 70 is further inserted, as shown in Figures 4(E) and (F), the groove 72 of the bit 70 comes into position to overlap with the elongated hole 38 in the front-to-back direction, and the groove 72 and the elongated hole 38 face each other. The metal ball 39 receives the repulsive force of the elastic member 50 and moves radially inward along the surface shape of the groove 72.

[0044] In the state shown in Figure 4(F), the metal ball 39 engages with the groove 72 of the bit 70 and the protrusion 42 of the guide sleeve 40, locking the bit 70 in place. If one attempts to pull the bit 70 forward from the state shown in Figure 4(F), the metal ball 39 attempts to move radially outward along the surface shape of the groove 72, but this outward movement is restricted by the protrusion 42, as shown in Figures 5(A) and (B). Therefore, the metal ball 39 gets caught in the groove 72 of the bit 70. Consequently, the bit 70 cannot be pulled forward from the state shown in Figure 5(B) unless the guide sleeve 40 is operated.

[0045] Figures 6(A) to 6(C) show the process of removing the bit 70 from the tool holder.

[0046] To remove the bit 70, first pull the guide sleeve 40 forward, moving it to a forward position against the biasing force of the guide spring 43. Then, as shown in Figure 6(A), the convex portion 42 of the guide sleeve 40 moves forward of the metal ball 39, and the concave portion 41 of the guide sleeve 40 is positioned radially outside the metal ball 39. When the bit 70 is pulled forward in this state, the metal ball 39 moves radially outward along the surface shape of the groove portion 72, resulting in a position that does not hinder further removal of the bit 70, as shown in Figure 6(B). If the bit 70 is pulled further forward, the bit 70 can be removed from the bit insertion hole 37, as shown in Figure 6(C).

[0047] Figure 7 is a front view of the elastic member 50 of the tool holder. The elastic member 50 is an annular spring formed by winding a plate material (for example, a thin sheet of metal) extending from one end 50a to the other end 50b in a substantially annular shape, with the other end 50b overlapping radially outward from the one end 50a.

[0048] Figure 8 is a cross-sectional view showing the state in which the metal sphere 39 has moved backward from the state in Figure 3 and is now radially inward of the elastic member 50. Figure 9 is a cross-sectional view AA of Figure 8. Figure 10 is a cross-sectional view showing the state in Figure 9 where the metal sphere 39 has moved radially outward.

[0049] As shown in Figure 9, the elastic member 50 is attached to the outer circumference of the anvil 33 and is configured such that the plate material is doubled in the radial direction throughout the circumferential direction.

[0050] As the metal sphere 39 moves radially outward from the state shown in Figure 9, the elastic member 50 elastically deforms so as to expand in the vertical direction, as shown in Figure 10. In the state shown in Figure 10, the elastic member 50 is configured such that its other end 50b overlaps radially outward from its first end 50a.

[0051] For example, when fastening a bolt by striking it with the bit 70, if the tip of the tool holder vibrates violently in the axial direction, the guide sleeve 40 may move forward due to inertia against the biasing force of the guide spring 43, and may no longer restrict the movement of the metal ball 39 radially outward. At this time, if the bit 70 also moves in the front-back direction due to vibration, the bit 70 will bounce the metal ball 39 radially outward, causing the elastic member 50 to deform significantly as shown in Figure 10.

[0052] Figure 11 is a cross-sectional view relating to a comparative example, showing a configuration in which the elastic member 50 in Figure 9 is replaced with an elastic member 850. Figure 12 is a cross-sectional view showing the state in Figure 11 where the metal sphere 39 has moved radially outward.

[0053] Unlike the elastic member 50, the elastic member 850 has a gap 851 between one end and the other. When the metal ball 39 moves radially outward from the state shown in Figure 11, the elastic member 850 elastically deforms so that the gap 851 widens, as shown in Figure 12. At this time, if the length of the gap 851 becomes greater than or equal to the diameter of the metal ball 39, there is a concern that the metal ball 39 may fall out through the gap 851 or become trapped in the gap 851 and be unable to return to the elongated hole 38, indicating room for improvement in terms of reliability (Problem 1 of the comparative example).

[0054] The elastic member 850 has a thicker plate material compared to the elastic member 50. This is to ensure the same biasing force (inward biasing force on the metal sphere 39 in the radial direction) in the elastic member 850, which has a configuration in which the plates do not overlap in the radial direction, as in the elastic member 50, which has a configuration in which the plates overlap twice in the radial direction. As a result, the elastic member 850 experiences greater bending stress when the metal sphere 39 moves radially outward and undergoes elastic deformation compared to the elastic member 50. Therefore, the elastic member 850 is at a relatively high risk of plastic deformation if elastic deformation due to the radially outward movement of the metal sphere 39 occurs repeatedly. When the elastic member 850 undergoes plastic deformation, the biasing force decreases, the holding force of the bit 70 decreases, and reliability decreases (Problem 2 of the comparative example).

[0055] This embodiment provides the following effects and advantages.

[0056] (1) As shown in Figure 10, the elastic member 50 is configured such that when the metal ball 39 is moved radially outward, the other end 50b overlaps radially outward with the one end 50a. Therefore, no circumferential gap is created between the one end 50a and the other end 50b. Thus, the metal ball 39 is prevented from falling out of the gap or from becoming trapped in the gap and being unable to return to the elongated hole 38, thereby improving the reliability of the tool holding device. In other words, problem 1 of the above comparative example is suitably solved.

[0057] (2) As shown in Figure 9, the elastic member 50 is attached to the outer circumference of the anvil 33 and is configured such that the plate material overlaps radially in a double layer over the entire circumferential direction. Therefore, compared to a configuration in which the plate material does not overlap radially, the plate thickness of the elastic member 50 required to ensure the same biasing force on the metal ball 39 can be reduced without changing the axial length, and the bending stress that occurs when the metal ball 39 moves radially outward and undergoes elastic deformation is reduced. Thus, the risk of plastic deformation of the elastic member 50 when elastic deformation due to the radially outward movement of the metal ball 39 occurs repeatedly is suppressed, and the reliability of the tool holding device is improved. In other words, problem 2 of the above comparative example is suitably solved.

[0058] (3) The anvil projection 60 has a second inclined surface 61 on its front surface that recedes towards the radially outward direction of the anvil 33, and the convex portion 42 of the guide sleeve 40 has a first inclined surface 46 that is in surface contact with the second inclined surface 61. Therefore, compared to a configuration in which, for example, the front surface of the anvil projection 60 and the rear surface of the convex portion 42 are planes perpendicular to the axial direction, the bending stress on the anvil projection 60 from the convex portion 42 of the guide sleeve 40 is reduced, so that durability can be ensured even if the front-to-back length of the anvil projection 60 is shortened. For this reason, the front-to-back length of the elastic member 50 can be increased by the same amount as the front-to-back length of the anvil projection 60, so that the elastic member 50 can cover a wide area of ​​the elongated hole 38, the reliability of the engagement between the elastic member 50 and the metal ball 39 is increased, and the reliability of the tool holding device is increased. Specifically, for example, when attempting to pull out the bit 70 without manipulating the guide sleeve 40, the reliability of the elastic member 50 guiding the metal ball 39 radially inward toward the protrusion 42 is increased, preventing the bit 70 from coming out simply by pulling it without manipulating the guide sleeve 40, thereby increasing the reliability of the tool holding device.

[0059] [Embodiment 2] Figure 13 is a cross-sectional view relating to Embodiment 2, showing a configuration in which the elastic member 50 in Figure 9 is replaced with an elastic member 250. Figure 14 is a cross-sectional view showing the state in Figure 13 where the metal sphere 39 has moved outward in the radial direction of the anvil 33.

[0060] As shown in Figure 13, the elastic member 250 is attached to the outer circumference of the anvil 33, and is configured such that the plate material overlaps radially in a double layer only in a portion of the circumferential direction. As shown in Figure 14, the elastic member 250 is configured such that when the metal sphere 39 moves radially outward, the other end 250b overlaps radially outward more than the one end 250a.

[0061] Similar to Embodiment 1, this embodiment also effectively solves problem 1 of the comparative example because, when the metal sphere 39 moves radially outward, no circumferential gap is created between one end 250a and the other end 250b.

[0062] [Embodiment 3] Figure 15 is a cross-sectional view relating to Embodiment 3, showing a configuration in which the elastic member 50 in Figure 9 is replaced with an elastic member 350. Figure 16 is a cross-sectional view showing the state in Figure 15 where the metal sphere 39 has moved outward in the radial direction of the anvil 33.

[0063] As shown in Figure 15, the elastic member 350 is attached to the outer circumference of the anvil 33, and is configured such that the plate material overlaps three times radially throughout the circumferential direction. Therefore, compared to Embodiment 1, the plate thickness required to ensure the same biasing force on the metal sphere 39 can be reduced, and the bending stress that occurs when the metal sphere 39 moves radially outward and undergoes elastic deformation is reduced. If the plate thickness is acceptable, the number of overlapping plates in the radial direction may be four or more.

[0064] Although the present invention has been described above using embodiments as examples, the present invention is not limited to these embodiments. Various modifications are possible to each of the matters specifically described in the embodiments within the scope of the claims.

[0065] The engaging member of the present invention is not limited to a metal sphere 39, but may be, for example, a ceramic sphere. By making the engaging member of a material with a lower density than the elastic member, the kinetic energy of the engaging member is reduced when the tip tool flips the engaging member radially outward, the amount of deformation of the elastic member is suppressed, and the bending stress on the elastic member is reduced.

[0066] The guide sleeve 40 may be made of a resin molded body. In this case, parts of the guide sleeve 40 that are prone to wear due to engagement with the metal ball 39, such as the protruding portion 42, may be made of metal by composite molding. The number of elongated holes 38 and metal balls 39 may be one.

[0067] The present invention is not limited to impact drivers and can be applied to any work machine that holds a cutting tool such as a bit. The present invention is not limited to cordless work machines and may also be corded work machines that operate on power supplied from an external AC power source via a power cord. [Explanation of Symbols]

[0068] 1…Work implement, 10…Housing, 11…Motor housing, 12…Handle section, 13…Battery pack mounting section, 14…Tail cover, 15…Trigger switch, 16…Forward / reverse switch, 17…Battery pack, 18…Hammer case, 19…Illumination LED, 20…Motor, 21…Motor shaft, 28…Reduction mechanism, 29…Spindle, 31…Hammer spring, 32…Hammer, 33…Anvil (tool holder), 34…Fan, 35…Control board, 36…Sensor / inverter board, 37…Bit insertion hole, 38…Slotted hole, 39…Metal ball (engaging member) 40... Guide sleeve (operating member), 41... Recess, 42... Protrusion (first restricting part), 43... Guide spring (biasing member), 44... Washer (spring receiving member), 45... Retaining ring, 46... First inclined surface, 49... Bearing, 50... Elastic member, 50a... One end, 50b... Other end, 56... Shaft part, 57... Wing part, 59... Elastic member mounting groove, 60... Anvil projection (second restricting part), 61... Second inclined surface, 70... Bit, 72... Groove part, 80... Circuit board case, 85... Operation panel part, 250... First elastic member, 350... First elastic member, 850... First elastic member.

Claims

1. Motor and, A tool holding device rotated by the motor, A work machine having, The tool holding device is A tool holder extending in the front-rear direction, having an insertion hole into which a bit can be inserted from front to rear, and an elongated hole for supporting an engaging member that can engage with the bit so as to be movable between a front position and a rear position, A substantially cylindrical operating member that is movable between a forward position and a rearward position on the outer circumference of the tool holder, the operating member having a first restricting portion that is located outside the engaging member in the radial direction of the tool holder and restricts the outward movement of the engaging member in the radial direction when the operating member is in the rearward position and the engaging member is in the forward position, When the operating member is in the rear position and the engaging member is in the rear position, a substantially annular elastic member is located outside the engaging member in the radial direction, and the elastic member deforms elastically when the engaging member in the rear position moves outward in the radial direction, It has, The elastic member has an annular portion that extends substantially in an annular shape on the outer circumference of the tool holder, The annular portion is composed of an annular spring formed by winding a plate material extending from one end to the other in a substantially annular shape, and the annular portion is attached to the outer circumference of the tool holder, and is configured such that when the engaging member is moved outward in the radial direction, the other end overlaps radially outward from the one end. A work machine characterized by the following features.

2. A work machine according to claim 1, With the annular portion attached to the outer circumference of the tool holder, the plate material is configured to overlap more than twice in the radial direction overall in the circumferential direction. A work machine characterized by the following features.

3. A work machine according to claim 1, The tool holder has a second restricting portion that restricts the elastic member from moving forward, The second restricting portion is configured to protrude radially outward from the outer circumference of the tool holder beyond the other end of the annular portion, in front of the elastic member. A work machine characterized by the following features.

4. A work machine according to claim 1, The tool holder has a second restricting portion that restricts the movement of the operating member backward, The second restricting portion has a second inclined surface on its front surface that recedes as it moves radially outward from the tool holder, The first regulating portion of the operating member has a first inclined surface that is in surface contact with the second inclined surface. A work machine characterized by the following features.

5. A work machine according to claim 1, The engaging member is made of a material with a lower density than the elastic member. A work machine characterized by the following features.

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