Impact tools

Abstract

To provide an impact tool capable of surely retreating two balls, for inserting smoothly a tip tool to a tool holder.SOLUTION: A hammer drill 1 comprises: a tool holder 10; two balls 35, 35 provided in storage holes 45, 45 of the tool holder 10 respectively; a guide washer 33 for energizing by a coil spring 34, the balls 35, 35 to a front side of the storage holes 45, 45; a pressing ring 32 adjacently arranged on a front side of the guide washer 33; and an operation sleeve 31 for moving forward and rearward, the pressing ring 32 between a lock position and a lock release position of both the balls 35, 35. A front face of the guide washer 33 has a protrusion part 42 protruded to the pressing ring 32 side, and by the protrusion part 42, the guide washer 33 is in an inclined posture inclined from an axial line A of the tool holder 10, at the lock position of the pressing ring 32, and one ball 35 is movable rearward relative to the other ball 35.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to impact tools such as electric hammers and hammer drills.

Background Art

[0002] In impact tools such as electric hammers and hammer drills, the rotation of a motor is converted into the reciprocating motion of a piston by a crank mechanism or the like inside a housing. Then, an impactor that reciprocates in conjunction with the piston directly impacts or indirectly impacts the rear end of a tip tool mounted on a tool holder via an intermediate member. In this impact tool, a chuck mechanism (mounting portion) for inserting and mounting a tip tool into a tool holder is provided at the tip of the housing. In this mounting portion, as disclosed in Patent Document 1, a pair of balls that are movable in the axial direction and radial direction of the tool holder are accommodated in a pair of accommodation holes formed in the tool holder. These balls are biased to a forward position in the accommodation hole by a guide washer (contact member) that is biased forward by a coil spring. A pressing ring is externally mounted on the tool holder. The pressing ring is movable back and forth between a lock position where it is located outside the balls and projects the balls into the tool holder, and an unlock position where it retracts rearward from the outside of the balls and allows the balls to retract from the tool holder. The pressing ring is held on the inner circumference of an operation sleeve and is biased to the lock position by a coil spring. When the operation sleeve is retracted, the pressing ring slides to the unlock position, enabling the attachment and detachment of the tip tool.

[0003] The guide washer has a conical receiving portion that projects rearward as it goes toward the center. A retreat portion that projects rearward with an angle with respect to the axis of the tool holder smaller than that of other portions is recessed in a part of the receiving portion. By fitting the lower ball into this retreat portion, the positions of the two balls are displaced back and forth. In this mounting portion, when the rear end of the tip tool is inserted into the tool holder, the upper ball first intrudes between the pressing ring and the receiving portion and retracts from within the tool holder, tilting the guide washer. Further, when the tip tool is retracted, the lower ball also intrudes between the pressing ring and the receiving portion and retracts from within the tool holder. Then, when the concave groove provided on the outer periphery of the tip tool reaches the position of the ball, the two balls advance by the biasing force of the coil spring and fit into the concave groove, integrating the tip tool with the tool holder in the rotational direction. Therefore, it becomes possible to insert and mount the tip tool into the tool holder only by pushing it in, without retracting the operation sleeve.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the invention of Patent Document 1, since the position of the ball is shifted by the retraction portion provided partially on the guide washer, when the tip tool is inserted, there may be a case where the retraction of the ball into the retraction portion is not performed smoothly. Although it is conceivable to increase the protruding amount of the retraction portion rearward to increase the movement range of the ball, when the tip tool is pushed in, the component force applied in the radial direction of the guide washer becomes larger than the component force applied in the pushing direction of the guide washer via the retraction portion, and there is a possibility that the tip tool cannot be pushed in.

[0006] Therefore, an object of the present disclosure is to provide an impact tool that can surely retract two balls and smoothly insert and mount a tip tool into a tool holder.

Means for Solving the Problems

[0007] To achieve the above object, the present disclosure includes a cylindrical tool holder into which the rear end of a tip tool can be inserted from the front, Two balls that are axially movable forward and backward in a pair of receiving holes drilled radially into the tool holder and are provided so as to be able to protrude from and retract into the inner surface of the tool holder by movement in the radial direction of the tool holder, and A ring-shaped contact member that is externally mounted so as to be movable forward and backward on the tool holder and biases both of the balls toward the front side of the receiving holes by a biasing member, and A pressing ring that is externally mounted so as to be movable forward and backward on the tool holder and is disposed adjacent to the front side of the contact member and is biased forward by the biasing member, and An operation sleeve that is externally mounted on the tool holder, against which the pressing ring abuts on the inner peripheral side, and that is movable forward and backward between a front locking position where the pressing ring is positioned radially outside and protrudes both of the balls radially inward from the inner surface of the tool holder and a rear unlocking position where the pressing ring retreats from the radially outer sides of both of the balls and allows the both balls to retreat from their protruding positions into the tool holder, and So as to overlap A striking tool including: on at least one of the opposing surfaces of the opposing surfaces of the contact member and the pressing ring, and outside one of the balls in the radial direction, a protruding portion that protrudes from one of the opposing surfaces toward the other opposing surface side, and when the protruding portion abuts on the other opposing surface side, the contact member is in an inclined posture inclined from the axis of the tool holder at the locking position of the pressing ring before the rear end of the tip tool is inserted into the tool holder, and when the rear end of the tip tool is inserted into the tool holder, the ball on the side where the protruding portion is provided is capable of moving rearward earlier than the other ball. According to the present disclosure, the two balls can be reliably retracted and the tip tool can be smoothly inserted and attached to the tool holder. Therefore, the insertability of the tip tool is improved.

Advantages of the Invention

[0008] According to the present disclosure, the two balls can be reliably retracted and the tip tool can be smoothly inserted and attached to the tool holder. Therefore, the insertability of the tip tool is improved.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0010] In one embodiment of the present disclosure, the protruding portion may be provided on the front surface of the abutting member. According to this configuration, the inclined posture of the abutting member can be easily obtained. In one embodiment of the present disclosure, the abutting member may have a disk shape that is uniform in the circumferential direction except for the protruding portion. According to this configuration, the shape of the abutting member becomes simple. In one embodiment of the present disclosure, the central portion of the abutting member may have a conical shape that retreats toward the center. According to this configuration, the ball can move smoothly backward. In one embodiment of the present disclosure, a part of the circumferential direction in the conical shape portion bulges backward so that the angle with respect to the axis of the tool holder becomes smaller, and a protruding portion is provided on the radially outer side of the part, and one ball may be further movable backward by the bulging portion of the conical shape. According to this configuration, the ball can be more reliably retracted backward.

[0011] In one embodiment of the present disclosure, the conical shape is provided at the central portion of the contact member, and a flat portion may be provided on the outer periphery of the central portion. According to this configuration, even if a protruding portion is provided on the contact member, the pressing ring can be stably urged. In one embodiment of the present disclosure, the biasing member may be a conical coil spring that increases in diameter toward the front. According to this configuration, the biasing force can be efficiently transmitted in accordance with the shape of the contact member. In one embodiment of the present disclosure, a second flat portion against which the front end of the coil spring abuts may be formed on the outer periphery of the contact member. According to this configuration, the biased state of the contact member is stabilized.

Example

[0012] Hereinafter, examples of the present disclosure will be described with reference to the drawings. FIG. 1 is a central longitudinal sectional view showing an example of a hammer drill 1 which is a striking tool. In the hammer drill 1, a motor housing 3 is vertically connected to the lower front side of a main body housing 2. A motor 4 with an output shaft 5 facing upward is accommodated in the motor housing 3. Above the motor housing 3 within the main body housing 2, a gear housing 6 is provided. In the gear housing 6, a crankshaft 7 and an intermediate shaft 8 that mesh with the output shaft 5 are provided in parallel. A cylindrical front housing 9 extending forward is assembled to the front side of the gear housing 6. A cylindrical tool holder 10 is coaxially and rotatably supported within the front housing 9. A handle housing 11 is connected to the rear portion of the main body housing 2. A housing cover 12 that covers the front housing 9 is connected to the front portion of the main body housing 2. The intermediate shaft 8 meshes with a bevel gear 13 provided at the rear end of the tool holder 10. A switch 14 and a switch lever 15 are provided on the handle housing 11. A power cord 16 is connected to the lower portion of the handle housing 11.

[0013] The tool holder 10 has a large-diameter portion 17 inside the front housing 9. The front end of the large-diameter portion 17 tapers towards the front and becomes a small-diameter portion 18 that protrudes from the front housing 9. The small-diameter portion 18 is provided with a mounting portion 30 for inserting and mounting the tip tool 50. The mounting portion 30 will be described later. A piston 20 is provided inside the large-diameter portion 17. The piston 20 is connected to the eccentric pin 21 of the crankshaft 7 via a connecting rod 22. Inside the large-diameter portion 17 in front of the piston 20, a striker 24 is accommodated via an air chamber 23. Inside the large-diameter portion 17 in front of the striker 24, an intermediate member 25 is accommodated. A change lever (not shown) is provided on the left side surface of the main body housing 2. By operating the change lever, three operation modes, namely the hammer mode, the hammer drill mode, and the drill mode, can be selected. In the hammer mode, the crankshaft 7 is rotated while the rotation of the tool holder 10 is locked to impart an impact to the tip tool 50. In the hammer drill mode, the crankshaft 7 and the intermediate shaft 8 are operated simultaneously to impart an impact and rotation to the tip tool 50. In the drill mode, no impact is imparted, and the intermediate shaft 8 is rotated to rotate the tip tool 50 together with the tool holder 10.

[0014] As also shown in Fig. 2A, a ring-shaped stopper rubber 26 is attached to the tip of the small-diameter portion 18 of the tool holder 10. The mounting portion 30 is provided between the stopper rubber 26 and the front housing 9. The mounting portion 30 includes an operation sleeve 31, a pressing ring 32, a guide washer 33, a coil spring 34, and two balls 35, 35. The operation sleeve 31 is externally mounted on the small-diameter portion 18 between the stopper rubber 26 and the front housing 9 and is movable back and forth. A ring-shaped stopper portion 36 is formed on the inner circumference of the operation sleeve 31. The stopper portion 36 abuts against the stopper rubber 26 at the forward position of the operation sleeve 31. The pressing ring 32 is externally mounted on the small-diameter portion 18 within the operation sleeve 31. The inner circumference of the pressing ring 32 has a stepped shape where the front side is an enlarged-diameter portion 37, the rear side is a reduced-diameter portion 38, and the intermediate portion is a tapered portion 39 connecting the two. The pressing ring 32 is movable back and forth within the operation sleeve 31, and when moving forward, its advancement is restricted at the position where it abuts against the stopper portion 36.

[0015] The guide washer 33 has a disc shape and is externally mounted on the small-diameter portion 18 within the operation sleeve 31. The guide washer 33 has a larger diameter than the pressing ring 32, and the central portion has a conical receiving portion 40 that protrudes rearward as it goes from the outer circumference toward the center. However, the conical shape of the receiving portion 40 is not uniform over the entire circumference. As shown in FIG. 4, the upper half side 40B of the receiving portion 40 has a smaller angle with respect to the axis A of the tool holder 10 than the lower half side 40A of the receiving portion 40, and is formed unevenly up and down. As a result, the protruding amount of the upper half side 40B rearward is larger than the protruding amount of the lower half side 40A rearward. On the outer circumference of the receiving portion 40, a ring-shaped inner flat portion 41 orthogonal to the axis A is formed. At the center in the left-right direction above the inner flat portion 41, a protruding portion 42 protruding forward is formed. On the outermost circumference of the guide washer 33, a ring-shaped outer flat portion 43 orthogonal to the axis A is formed.

[0016] The coil spring 34 is externally mounted on the small-diameter portion 18 between the front end of the large-diameter portion 17 of the tool holder 10 and the guide washer 33. The coil spring 34 has a conical shape with a smaller diameter from the front end toward the rear. The front end of the coil spring 34 abuts against the rear surface of the outer flat portion 43 of the guide washer 33. The rear end of the coil spring 34 abuts against the front end of the large-diameter portion 17. Therefore, the coil spring 34 biases the guide washer 33 forward, and through the guide washer 33, biases the pressing ring 32 and the operation sleeve 31 forward. In the normal state shown in Fig. 2A, the operation sleeve 31 is in the forward position where it abuts against the stopper rubber 26 by the biasing force of the coil spring 34. The pressing ring 32 is in the forward position where it abuts against the stopper portion 36 of the operation sleeve 31. The guide washer 33 is in the forward position where the inner flat portion 41 abuts against the rear surface of the pressing ring 32. However, since the protrusion 42 of the guide washer 33 abuts against the upper rear surface of the pressing ring 32, the guide washer 33 is not coaxially aligned with the axis A in the forward position and abuts against the pressing ring 32 in an inclined posture where the upper side is located rearward of the lower side.

[0017] A pair of receiving holes 45, 45 are formed in the small-diameter portion 18 of the tool holder 10. The receiving holes 45, 45 are arranged at point-symmetrical positions centered on the axis A and penetrate the small-diameter portion 18 in the radial direction. The receiving hole 45 is formed long in the front-rear direction, and both the front and rear ends are formed in a tapered shape that tapers toward the axis A side from the outer surface of the small-diameter portion 18. A pair of ridges 46, 46 extending in the front-rear direction are formed on the inner circumference of the small-diameter portion 18 at a position with a 90° phase difference from the receiving hole 45. The balls 35, 35 are received in the receiving holes 45, 45 and can roll back and forth in the respective receiving holes 45. Each ball 35 can also roll in the radial direction within the receiving hole 45. Each ball 35 can roll to a position where a part of it protrudes into the small-diameter portion 18 on the axial center side of the small-diameter portion 18. In the forward position (lock position) of the operation sleeve 31 and the pressing ring 32 shown in Fig. 2A, the reduced-diameter portion 38 of the pressing ring 32 is located outside the balls 35, 35. Therefore, the balls 35, 35 are locked in the protruding position into the small-diameter portion 18, and the movement radially outward is restricted.

[0018] In this state, the lower half side 40A of the receiving portion 40 of the guide washer 33 abuts against the lower ball 35A (hereinafter, when distinguishing between the upper and lower, the lower ball is denoted as 35A and the upper ball is denoted as 35B). Therefore, the ball 35A is locked in the protruding position into the small-diameter portion 18 on the front side of the receiving hole 45. On one hand, the upper half side 40B of the receiving part 40 with a large inclination angle is inclined backward more than the lower half side 40A. Therefore, a retreat space S in which the ball 35B can move backward is formed between the pressing ring 32 and the upper half side 40B. However, even if the ball 35B retreats until it contacts the upper half side 40B, the contact state with the reduced-diameter part 38 of the pressing ring 32 does not change. Therefore, the protruding position of the ball 35B into the small-diameter part 18 is maintained. At the rear end of the tip tool 50, a tapered end part 51 that tapers backward is formed. On the outer periphery of the rear end of the tip tool 50, at point-symmetrical positions centered on the axis, a pair of concave grooves 52, 52 are formed in the front-rear direction. At positions where the phase is different by 90° from the concave grooves 52, 52, a pair of engaging grooves 53, 53 extending forward from the rear end are formed on the outer periphery of the rear end of the tip tool 50.

[0019] In the hammer drill 1 configured as described above, when the tip tool 50 is inserted and attached to the attachment part 30, as shown in FIG. 2A, with the operation sleeve 31 in the forward position, the rear end of the tip tool 50 is inserted into the small-diameter part 18 with the engaging grooves 53, 53 aligned with the ridges 46, 46 of the small-diameter part 18. Then, the tapered end part 51 of the tip tool 50 contacts the balls 35A, 35B. However, since a retreat space S is formed behind the upper ball 35B, the ball 35B retreats in the accommodation hole 45 while remaining in contact with the pressing ring 32. At this time, as shown in FIG. 2B, the ball 35B retreats until its center is located behind the rear end of the pressing ring 32 and contacts the upper half side 40B of the receiving part 40. Therefore, it does not prevent the retreat of the tip tool 50.

[0020] When the tip tool 50 continues to retract, as shown in Fig. 2C, the lower ball 35A is pressed against the tapered end 51 of the tip tool 50 and moves to the rear part of the receiving hole 45. Then the ball 35A wedges between the pressing ring 32 and the lower half side 40A of the receiving part 40. Thus, the ball 35A moves the lower part of the guide washer 33 rearward. Subsequently, the upper ball 35B is also pressed against the tapered end 51 and moves to the rear part of the receiving hole 45. Then the ball 35B wedges between the pressing ring 32 and the upper half side 40B of the receiving part 40. Thus, the ball 35B moves the upper part of the guide washer 33 rearward. When the tip tool 50 further retracts, as shown in Fig. 3A, the balls 35A and 35B move radially outward between the pressing ring 32 and the guide washer 33 while riding relatively up on the tapered end 51. Since the balls 35A and 35B remain in contact with the pressing ring 32, the pressing ring 32 does not retract even if the hammer drill 1 is upward.

[0021] Then, when the tip tool 50 further retracts, as shown in Fig. 3B, the balls 35A and 35B ride relatively over the tapered end 51 onto the rear end circumferential surface of the tip tool 50 and retract radially outward from the receiving holes 45, 45. If the tip tool 50 retracts as it is, the concave grooves 52, 52 reach the inside of the balls 35A and 35B. Then, as shown in Fig. 3C, the balls 35A and 35B are pushed by the receiving part 40 of the guide washer 33 and move to the inside of the pressing ring 32, returning to the protruding position from the receiving holes 45, 45. Thus, the balls 35A and 35B engage with the concave grooves 52, 52. In this way, the tip tool 50 is prevented from coming off by the balls 35A and 35B and is integrally connected to the tool holder 10 in the rotational direction.

[0022] After the tip tool 50 is installed, select the operation mode with the change lever and push in the switch lever 15. Then, the switch 14 turns ON, the motor 4 is driven, and the output shaft 5 rotates. In the case of the hammer mode, the rotation of the output shaft 5 is transmitted to the crankshaft 7. However, the rotation of the intermediate shaft 8 is not transmitted from the bevel gear 13 to the tool holder 10. Therefore, due to the eccentric movement of the eccentric pin 21, the piston 20 moves back and forth via the connecting rod 22. Then, the striker 24 moves back and forth via the air chamber 23, and the striker 24 indirectly strikes the tip tool 50 via the intermediate piece 25. Therefore, cutting of the workpiece by the tip tool 50 becomes possible. In the case of the hammer drill mode, the rotation of the output shaft 5 is transmitted to the crankshaft 7. Also, the rotation of the intermediate shaft 8 is transmitted from the bevel gear 13 to the tool holder 10. Therefore, the tool holder 10 rotates, and the tip tool 50 rotates together with the striking. On the other hand, in the case of the drill mode, the crankshaft 7 does not rotate, and the rotation of the intermediate shaft 8 is transmitted to the tool holder 10. Therefore, the piston 20 does not move back and forth, and the tip tool 50 rotates, enabling drilling of the workpiece.

[0023] When removing the tip tool 50 from the tool holder 10, the operation sleeve 31 is retracted from the state of Fig. 3C against the biasing force of the coil spring 34. Then, the pressing ring 32 is also pressed by the stopper portion 36 and retracts, and the guide washer 33 also retracts. Therefore, the pressing ring 32 moves to the unlocking position where the diameter-expanding portion 37 is outside the balls 35, 35. When the tip tool 50 is pulled forward as it is, the balls 35, 35 engaged with the concave grooves 52, 52 come out of the concave grooves 52, 52 and move radially outward of the accommodation holes 45, 45. Therefore, the tip tool 50 whose retention by the balls 35, 35 is released can be removed.

[0024] Thus, according to the hammer drill 1 of the above-described embodiment, a protrusion 42 (protruding portion) protruding toward the pressing ring 32 side is provided on the opposing surface of the guide washer 33 (contact member) with the pressing ring 32. Due to this protrusion 42, at the locking position of the pressing ring 32, the guide washer 33 assumes an inclined posture inclined from the axis A of the tool holder 10, and the ball 35B can move rearward more than the ball 35A. According to this configuration, the two balls 35A and 35B can be reliably retracted, and the tip tool 50 can be smoothly inserted into and attached to the tool holder 10. Therefore, the insertability of the tip tool 50 is improved.

[0025] The protrusion 42 is provided on the front surface of the guide washer 33. Therefore, the inclined posture of the guide washer 33 can be easily obtained. The guide washer 33 has a uniform disk shape in the circumferential direction except for the protrusion 42. Therefore, the shape of the guide washer 33 is simple. The central portion of the guide washer 33 is a conical receiving portion 40 that retreats toward the center. Therefore, the balls 35A and 35B can move smoothly backward. The upper half side 40B (a part in the circumferential direction) of the receiving portion 40 bulges backward so that the angle with respect to the axis A of the tool holder 10 becomes smaller. And the protrusion 42 is provided on the radially outer side of the upper half side 40B, and the ball 35B can be moved further backward by the upper half side 40B. Therefore, the ball 35B can be more reliably retracted backward.

[0026] The conical receiving portion 40 is provided in the central portion of the guide washer 33, and an inner flat portion 41 (flat portion) is provided on the outer periphery of the central portion. Therefore, even if the protrusion 42 is provided on the guide washer 33, the pressing ring 32 can be stably urged. The biasing member that biases the guide washer 33 is a conical coil spring 34 that has a larger diameter toward the front. Therefore, the biasing force can be efficiently transmitted according to the shape of the guide washer 33. An outer flat portion 43 (second flat portion) with which the front end of the coil spring 34 abuts is formed on the outer periphery of the guide washer 33. Therefore, the biased state of the guide washer 33 is stabilized.

[0027] Hereinafter, modified examples of the present disclosure will be described. If the receiving part's bulging portion allows the ball to retract, it may be made smaller circumferentially than half, provided that the receiving part's bulging portion may be absent. For example, like the guide washer 33a shown in Fig. 5, the receiving part 40 may be made into a uniformly conical shape in the circumferential direction. In this case as well, the inclined posture of the guide washer 33a can be obtained by the protrusion 42. The contact member may be conical in shape throughout rather than just at the central part. Conversely, the contact member may have a shape other than conical (e.g., spherical or planar). A structure that integrally connects the contact member to the tool holder in the rotational direction (e.g., fitting of two-sided widths) may be adopted between the contact member and the tool holder. The shape of the protruding part is not limited to the protrusion in the above form. The protruding part may be formed as a ridge that is long in the circumferential direction. A plurality of protruding parts may be provided. The protruding part may be provided on the rear surface of the pressing ring instead of the contact member. The form of the protruding part in this case can also be changed as appropriate. The contact member can also be inclined by partially increasing the wall thickness of the pressing ring instead of having a protrusion. The protruding part can also be provided on the opposing surfaces of both the contact member and the pressing ring. The coil spring is not limited to a conical shape. Biasing members other than coil springs can also be adopted.

[0028] In the above form, an example where a pair of receiving holes and balls are arranged above and below the tool holder has been described, but it is not limited to this arrangement. The present disclosure also includes cases where the receiving holes and balls are arranged on the left and right of the tool holder or in other phases. The form of the hammer drill is also, for example, such that the striking part has an intermediate axis parallel to the tool holder, and an arm is swingably provided via a swash bearing with its axis inclined on a boss sleeve provided on the intermediate axis, and a piston cylinder connected to the arm is moved back and forth. The direction and type of the motor are not limited to the above form. The operation mode is not limited to the three modes (hammer mode, hammer drill mode, drill mode) in the above form. For example, only two operation modes, the hammer drill mode and the hammer mode, may be selectable. A DC machine with a battery pack attached as a power source instead of an AC machine may also be used. The impact tool is not limited to a hammer drill, and the mounting part of the present disclosure is applicable even to an electric hammer having only an impact part.

Explanation of Signs

[0029] 1 ·· Hammer drill, 2 ·· Main body housing, 3 ·· Motor housing, 4 ·· Motor, 5 ·· Output shaft, 10 ·· Tool holder, 17 ·· Large diameter part, 18 ·· Small diameter part, 20 ·· Piston, 24 ·· Striker, 25 ·· Intermediate piece, 26 ·· Stopper rubber, 30 ·· Mounting part, 31 ·· Operation sleeve, 32 ·· Pressing ring, 33, 33a ·· Guide washer, 34 ·· Coil spring, 35 ·· Ball, 40 ·· Receiving part, 40A ·· Lower half side, 40B ·· Upper half side, 41 ·· Inner flat part, 42 ·· Protrusion, 43 ·· Outer flat part, 45 ·· Accommodation hole, 50 ·· Tip tool, 51 ·· Tapered end, A ·· Axis of the tool holder.

Claims

1. A cylindrical tool holder into which the rear end of the tip tool can be inserted from the front, Two balls provided so as to be movable back and forth in the axial direction of the tool holder within a pair of accommodation holes drilled radially in the tool holder and to be able to protrude from and retract into the inner surface of the tool holder by movement in the radial direction of the tool holder, A ring-shaped contact member that is externally mounted on the tool holder so as to be movable back and forth and biases both balls to the front side of the accommodation hole by a biasing member, A pressing ring that is externally mounted on the tool holder so as to be movable back and forth and is disposed adjacent to the front side of the contact member and is biased forward by the biasing member, An operation sleeve that is externally mounted on the tool holder and is movable back and forth between a front locking position where the pressing ring abuts on the inner peripheral side and overlaps the two balls on the outer side in the radial direction with respect to the two balls located on the front side of the accommodation hole so as to project the two balls from the inner surface of the tool holder to the inner side in the radial direction, and a rear unlocking position where the pressing ring retreats from the outer side in the radial direction of the two balls to allow the two balls to retreat from the protruding position into the tool holder, A striking tool including: on at least one of the opposing surfaces of the opposing surfaces of the contact member and the pressing ring, and outside one of the balls in the radial direction, a protruding portion that protrudes from one of the opposing surfaces toward the other opposing surface side; when the protruding portion abuts on the other opposing surface side, the contact member is in an inclined posture inclined from the axis of the tool holder at the locking position of the pressing ring before the rear end of the tip tool is inserted into the tool holder; and when the rear end of the tip tool is inserted into the tool holder, the ball on the side where the protruding portion is provided on the outer side in the radial direction can move backward earlier than the other ball.

2. The striking tool according to claim 1, wherein the protruding portion is provided on the front surface of the contact member.

3. The striking tool according to claim 2, wherein the contact member has a disk shape that is uniform in the circumferential direction except for the protruding portion.

4. The striking tool according to claim 3, wherein at least the central portion of the contact member has a conical shape that retreats toward the center.

5. A part of the circumferential direction in the conical portion bulges rearward so that the angle with respect to the axis of the tool holder becomes smaller, and the protrusion is provided on the radially outer side of the part. The ball on the side where the protrusion is provided on the radially outer side is further movable rearward by the conical bulging portion. The impact tool according to claim 4, characterized in that.

6. The conical shape is provided in the central portion of the contact member, and a flat portion that contacts the pressing ring is provided on the outer periphery of the central portion. The impact tool according to claim 4 or 5, characterized in that.

7. The biasing member is a conical coil spring that becomes larger in diameter toward the front. The impact tool according to any one of claims 1 to 6, characterized in that.

8. A second flat portion with which the front end of the coil spring contacts is formed on the outer periphery of the contact member. The impact tool according to claim 7, characterized in that.

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