JP4798910B2 - Axial force generator and mechanical chuck cylinder using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an axial force generator that converts a rotational motion into an axial movement using a screw mechanism, and particularly generates an axial force having a large boosting action at the stroke end regardless of the magnitude of the axial movement stroke. The present invention relates to a device and a mechanical chuck cylinder including the device.
[0002]
[Prior art]
In a machine tool, a chuck for gripping a rotary tool or a rotary workpiece generally has a structure that is opened and closed by a pull rod that moves in the axial direction on the axis of rotation. The pull rod is moved in the axial direction by a hydraulic cylinder called a chuck cylinder.
[0003]
For example, a work chuck mounted on the main spindle of a lathe has three or four claws that open and close simultaneously in the radial direction, and the opening and closing of the claws is caused by the axial movement of the pull rod inserted through the hollow hole of the main spindle. This is performed by converting the movement into a radial direction by a wedge mechanism or a cam mechanism and transmitting it to each claw. In order to move the pull rod in the axial direction, a hydraulic cylinder is mounted on the end of the main shaft opposite to the chuck, and the piston is connected to the pull rod to open and close the claw.
[0004]
The pull rod that opens and closes the main spindle chuck of the lathe generally uses a hollow rod so that a bar material can be supplied through the axis of the main spindle.
[0005]
[Problems to be solved by the invention]
Since the hydraulic chuck cylinder is mounted on the end of the spindle and rotates, it is necessary to supply hydraulic pressure using a rotary joint, which causes energy loss and seal replacement problems due to oil leakage at the rotary joint. Further, a high hydraulic pressure must always be supplied to the chuck cylinder while the chuck is gripping the workpiece, which raises the problem of an increase in the operating cost of the hydraulic pump and an increase in the temperature of the hydraulic oil. When the hydraulic oil temperature rises, it is transmitted to the spindle and the chuck, causing an error in machining dimensions due to thermal deformation.
[0006]
An object of the present invention is to obtain a purely mechanical chuck cylinder driven by an electric motor that is used in place of a hydraulic cylinder chuck. The rotational movement of the electric motor is converted into an axial movement and transmitted to a pull rod. A compact pure mechanical chuck cylinder capable of following a high-speed rotation of the main shaft without being affected by the stroke amount of the pull rod at the stroke end for gripping the shaft, and an axial force generator used therefor The challenge is to obtain.
[0007]
[Means for Solving the Problems]
The axial force generator of the present invention that has solved the above problems includes a primary screw 15 and a secondary screw 8 of the same lead disposed on a concentric cylinder, and a load clutch that transmits the rotation of the primary screw to the secondary screw. A member 7, a first sleeve 16 that moves in the axial direction by the rotation of the primary screw, a second sleeve 9 that moves in the axial direction by the rotation of the secondary screw, and a shaft disposed on the moving tip side of the second sleeve The force member 20, a plurality of boost chambers 32 formed at positions that equally divide the circumference between the opposed surfaces of the axial force member and the second sleeve, and are arranged in the boost chambers with an interval in the axial direction. The spherical or cylindrical passive body 34 and the spherical or cylindrical shape located between the adjacent passive bodies deviating from the line connecting the axial centers of the two passive bodies adjacent in the axial direction of each booster chamber On the front peripheral surface or side surface of the first sleeve And a wedge surface 33a that simultaneously pushes the pushing body of each booster chamber toward the passive body side, and rotationally drives the primary screw to move the stroke in the axial direction and the shaft at the stroke end. Generates a direction boost.
[0008]
In the axial force generating device having a preferred structure according to the present invention, the load clutch member 7 is screwed into the secondary screw 8, and the load clutch member and the second sleeve 9 are connected so as to be relatively rotatable and not movable relative to the axial direction. A locking body for forcibly holding the load clutch in the clutch disengaged state and a lock spring 39 for urging the locking body in the clutch disengaging direction are provided, and the first sleeve 16 contacts the load clutch member. When it moves to the base end side to the contact position, the locking body 38 is pushed against the urging force of the lock spring, and the forced disengagement state of the load clutch is released, and the first sleeve is released from the load clutch member. When they are separated from each other, the lock spring pushes the locking body to forcibly hold the clutch disengaged state.
[0009]
The mechanical chuck cylinder of the present invention comprises a fixed inner cylinder 5 having a fixed flange 6 at the base end, and a rotating outer cylinder 11 positioned outside thereof, and the primary screw is provided on the inner peripheral surface of the rotating outer cylinder. The axial force generating device having the above structure is provided between the fixed inner cylinder and the rotating outer cylinder, and is connected to the pull rod inserted into the center hole of the fixed inner cylinder at the tip of the axial force member 20. Connecting tools 24 and 25 are provided.
[0010]
In the axial force generator of the present invention described above, when the primary screw 15 is rotationally driven, the primary screw and the secondary screw 8 connected to the primary screw 15 via the load clutch member 7 are synchronously rotated. A first sleeve 16 connected to a member screwed or screwed to the primary screw 15 and a second sleeve 9 connected to a member screwed or screwed to the secondary screw 8 are both screws 15, 8. Since they have equal leads, they move synchronously in the axial direction. When reaching the stroke end regulated by the chuck claw coming into contact with the workpiece or the like, the axial movement of the axial force member 20 is blocked, and the blocking force is transmitted via the spheres or cylinders 34 and 35 of the boost chamber 32. Therefore, the axial movement of the second sleeve 9 is also prevented. Accordingly, the rotational load of the secondary screw 8 that causes the second sleeve 9 to advance and retract is increased, and the load clutch member 7 is disconnected. Therefore, the rotation of the secondary screw 8 stops and the axial movement of the second sleeve 9 stops.
[0011]
On the other hand, the primary screw 15 continues to rotate, and the first sleeve 16 advances further. Due to the relative forward movement of the first sleeve 16 with respect to the stopped second sleeve 9, the wedge surface 33 a pushes the pushing body 35 between the two passive bodies 34, 34 adjacent in the axial direction, and the pushing body 35 and the passive body 34 Due to the wedge action between the two, a large axial force is generated in a direction that attempts to separate the two passive bodies 34, 34. Since the second sleeve 9 that receives this axial force is fixed in the axial direction by the secondary screw 8 that is stopped, the axial force is transmitted to the axial force member 20. Therefore, if a pull rod for opening and closing the chuck is connected to the axial force member 20 with the couplers 24 and 25, a load is applied to the axial movement of the axial force member 20 from the chuck open state until the claw contacts the workpiece. Therefore, after the chuck claw comes into contact with the workpiece, a boosting action due to the axial movement of only the first sleeve 16 works. Thus, the workpiece is firmly gripped.
[0012]
When the primary screw 15 is rotated in the reverse direction, a large axial reaction force generated by the boosting force is applied to the thread surface of the secondary screw 8, and therefore the secondary screw 8 may immediately rotate. Only the primary screw 15 is rotated, and the first sleeve 16 is moved back in the axial direction. When the first sleeve 16 returns to a certain stroke, the pushing force of the pushing body 35 by the wedge surface 33a is released, and the rotational load of the secondary screw 8 is released, so that the load clutch member 7 enters and the secondary screw. 8 rotates synchronously with the primary screw 15 to simultaneously return the first sleeve 16 and the second sleeve 9. When the second sleeve 9 reaches the return stroke end, a rotational load is again applied to the secondary screw, so that the load clutch member 7 is disconnected, and only the primary screw 15 rotates, and only the first sleeve 16 returns. When the first sleeve 16 also reaches the return stroke end, the rotational load of the primary screw 15 increases, and this increase in load is detected by, for example, an increase in the current value of the electric motor that rotationally drives the primary screw. The electric motor is stopped and the rotation of the primary screw 15 is stopped.
[0013]
Note that the axial force of the axial force member 20 at the forward stroke end of the first sleeve 16 is controlled so that the current value of the drive motor is abrupt when the load of the second sleeve 9 increases and the load clutch member 7 is disconnected. This can be achieved by detecting the decrease and controlling the rotational speed of the electric motor from the detection point to control the movement stroke when the first sleeve 16 moves alone.
[0014]
The axial force generator having the above structure can generate a large boosting force at the forward stroke end regardless of the magnitude of the stroke, and generates a large workpiece or tool gripping force when used in a chuck cylinder. be able to. In addition, since a self-locking mechanism using a screw works at the stroke end on the advancing side and the return side, the advancing and returning positions of the axial force member 20 can be maintained if the electric motor is in a freely rotating state, and used when used as a chuck cylinder. Since the opening / closing position of the chuck pawl is held, the electric motor may be driven only when the chuck is opened / closed.
[0015]
A servo motor is used as the chuck cylinder drive motor, and this motor is rotated synchronously with the spindle driving motor of the machine tool, and the primary screw 15 is rotated relatively by giving a rotation difference between the two motors. For example, the chuck can be opened and closed while the spindle rotation is continued.
[0016]
Further, by adopting the means of claim 2, the disengagement state of the load clutch member 7 can be forcibly held, and the on / off operation of the clutch at an accurate timing can be ensured, A more reliable advance / retreat operation of the first sleeve 16 and the second sleeve 9 can be realized.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
FIGS. 1 to 4 are views showing a first embodiment of a mechanical chuck cylinder using the axial force generator of the present invention. In the figure, reference numeral 1 denotes a main shaft of the lathe, and 2 denotes a V-belt pulley fixed to the opposite end of the main shaft 1. A main shaft motor is connected to the V-belt pulley and the main shaft 1 rotates. Reference numeral 3 denotes a pull rod having a hollow hole 4 inserted through the hollow hole of the main shaft 1 so as to be movable in the axial direction.
[0018]
A fixed inner cylinder 5 having a center hole having the same diameter as the center hole of the main shaft 1 is fixed to the belt pulley 2 of the main shaft by a fixing flange 6 at the base end thereof. A load clutch member 7 is fitted on the base end side (fixed flange side) of the fixed inner cylinder 5 so as to be relatively rotatable and axially immovable. The secondary screw 8 is formed integrally with the clutch member 7 and is screwed into the inner periphery of the base end portion of the second sleeve 9.
[0019]
A rotating outer cylinder 11 is attached to the fixed flange 6 via a bearing 10 so as to be freely rotatable. A toothed belt pulley 12 is fixed to the base end side of the rotating outer cylinder 11, and a rotating motor 11 is driven to rotate by connecting a chuck opening / closing motor (not shown) to the toothed belt pulley with a toothed belt. . A recess 14 into which the clutch pawl 13 of the load clutch member 7 is engaged is provided on the inner periphery on the proximal end side of the rotating outer cylinder 11. The primary screw 15 is formed on the inner peripheral surface of the rotating outer cylinder 11 and is screwed with the outer periphery on the proximal end side of the first sleeve 16.
[0020]
As shown in FIG. 2, the clutch pawl 13 of the load clutch member 7 can be raised and lowered around the axial pin 17, and in the standing state shown in FIG. 2, the tip protrudes from the outer peripheral surface of the load clutch member 7. It engages with a recess 14 provided on the inner peripheral surface of the rotating outer cylinder 11 fitted on the outside. This standing state of the clutch pawl 13 is held by a slider 19 urged toward both sides of the clutch pawl 13 by a compression coil spring 18. In this state, the rotation of the rotating outer cylinder 11 is transmitted to the load clutch member 7 through the clutch pawl 13. When a rotational load is applied to the secondary screw 8, and hence the load clutch member 7, the clutch pawl 13 lies in a state where the slider 19 is pushed in against the urging force of the coil spring 18 by the tangential force. The tip of the clutch pawl 13 is pushed to the position of the outer peripheral surface of the load clutch member 7 by this overturning, and the rotation of the rotating outer cylinder 11 is not transmitted to the load clutch member 7 and thus the secondary screw 8 (the load clutch member is Cut). When the rotating outer cylinder 11 rotates with the load torque of the secondary screw 8 released, when the clutch pawl 13 and the recess 14 coincide with each other, the clutch pawl 13 is raised by the urging force of the compression coil spring 18 to be recessed. Then, the rotation of the rotating outer cylinder 11 is transmitted to the load clutch member 7, and hence the secondary screw 8 (the load clutch member is engaged) (see FIG. 2).
[0021]
A cylindrical axial force member 20 is fitted on the outer periphery on the front end side of the fixed inner cylinder 5, and a guide sleeve 21 is fitted on the outer side thereof. The guide sleeve 21 is not rotatable relative to the fixed pin 22 and cannot move in the axial direction by the radial fixed pin 22 erected at the tip of the fixed inner cylinder 5. The fixed pin 20 passes through the long hole 20a in the axial direction of the axial force member 20, and the axial force member 20 is not relatively rotatable and is movable in the axial direction within the range of the length of the long hole 20a. The distal end portion of the rotating outer cylinder 11 is rotatably fitted via a bearing member 11a, and the axial movement is restricted by a presser nut 23 screwed to the distal end of the guide sleeve 21.
[0022]
The distal end of the axial force member 20 is in contact with the proximal end surface of the flanged nut 24 screwed to the distal end of the pull rod 3, and the flange 24 a of the flanged nut 2 is fixed to the outer periphery of the distal end side of the axial force member 20. The front end side is locked by a split coupling 25. Accordingly, the axial movement of the axial force member 20 is transmitted to the pull rod 3, and the relative positional relationship between the two axial directions can be adjusted by rotating the hooked nut 24.
[0023]
A strip-shaped projection 26 shown in FIG. 3 is formed at four locations around the circumference of the first sleeve 16, and the tip of the strip projection can be moved in the axial direction by a guide notch 27 provided on the proximal end side of the guide sleeve 21. It is guided to. A stepped U-shaped recess 28 is provided in the inner peripheral side portion of the strip protrusion at the tip of the second sleeve 9, and is formed on the inner diameter side portion of the guide notch 27 at the base end of the axial force member 20. The U-shaped opposed recess 29 is provided, the wedge chamber 30 is formed by these recesses 28, 29, and the side surface is opened toward the wedge chamber 30 at the step portion 31 of the recess 28. A force chamber 32 is formed. A wedge 33 provided integrally with the inner peripheral surface of the strip projection 26 is inserted into the wedge chamber 30, and the wedge surface 33 a of the wedge 33 faces the boost chamber 32. Two passive spheres 34 are inserted into the booster chamber 32 with an interval in the axial direction, and a pushing sphere 35 is inserted between the passive spheres while being biased toward the wedge 33. When the first sleeve 16 advances in a state where the axial movement of the second sleeve 9 is stopped, the wedge 33 moves to the front end side in the wedge chamber 30, and the wedge surface 33a moves the push ball 35 into the two passive spheres 35. Push between the spheres 34. At this time, since a wedge action is generated between the pushing sphere 35 and the passive sphere 34, the two passive spheres 34 are pushed away from each other by a boost due to the two-stage wedge action. Since the proximal-side passive sphere is fixed to the axial movement by the secondary screw 8, the distal-side passive sphere pushes the proximal end of the axial force member 20 to generate a large axial force.
[0024]
In the illustrated embodiment, the outer periphery of the boosting chamber 32 is closed by the cover member 36, and the distal end of the cover member is screwed to the axial force member 20, and the base end and the second sleeve 9 are connected to each other. By urging toward the base end side by the coil spring 37 provided therebetween, when the wedge 33 returns, the axial force member 20 is pulled back to the base end side to push out the pushing ball 35 toward the wedge 33 side. (See FIG. 3).
[0025]
Next, the axial force generation operation and the return operation of the illustrated embodiment will be described. When the rotating outer cylinder 11 is rotationally driven by a chuck opening / closing motor (not shown), the primary screw 15 and the secondary screw 8 connected via the load clutch member 7 rotate synchronously, and the first sleeve 16 and the first The two sleeves 9 move together in the axial direction. At this time, the position of the wedge 33 in the wedge chamber 30 does not change, and the axial force member 20 is pushed by the second sleeve 9 via the three spheres 34, 35, 34 to be integrated into the shaft. Move in the direction (forward). When the chuck claw of the spindle chuck grips the workpiece, a pulling load is applied to the pull rod 3, and the axial movement of the axial force member 20 stops. For this reason, the axial movement of the second sleeve 9 becomes impossible, and a rotational load acts on the secondary screw 8, so that the clutch member 7 is disconnected and only the primary screw 15 rotates. In this state, that is, in a state in which the second sleeve is stopped and only the first sleeve 16 is advanced, the wedge 33 is advanced in the wedge chamber 30, and the pushing sphere 35 is pushed between the passive spheres 34, thereby the axial force member. A large axial force is transmitted to 20, which is transmitted to the pull rod 3, and the spindle chuck firmly holds the workpiece.
[0026]
When opening the spindle chuck, the rotating outer cylinder 11 is rotated in the reverse direction in this state. At the start of rotation, a large thrust acts on the thread surface of the secondary screw 8, so the secondary screw 8 cannot rotate, but only the primary screw 15 rotates and the wedge 33 moves backward in the wedge chamber 30. The pushing ball 35 is pushed out by the urging force of the spring 37, and the surface pressure acting on the secondary screw is rapidly reduced. Therefore, the clutch member 7 is inserted in a state where the clutch pawl 13 and the recess 14 of the rotating outer cylinder 11 coincide with each other, and the primary screw 15 and the secondary screw 8 rotate synchronously, and the first sleeve 16 and the second sleeve 9 To return. In a normal case, the second sleeve 9 reaches the return end first, so that the return movement of the second sleeve is prevented, and a rotational load is again applied to the secondary screw 8 and the load clutch member 7 is disconnected. In this state, when only the primary screw 15 rotates and the first sleeve 16 reaches the return end, a rotational load acts on the primary screw 15 and the chuck opening / closing motor stops.
[0027]
5 to 7 are views showing a second embodiment of the mechanical chuck cylinder using the axial force generator of the present invention, in which a secondary screw 8 is provided on the outer periphery of the fixed inner cylinder 5, It differs from the first embodiment in that the load clutch member 7 is provided with a locking means for holding the clutch pawl 13 in the cut state and the pushing sphere 35 is arranged to be biased in the radial direction. Hereinafter, these differences will be described.
[0028]
The secondary screw 8 of the second embodiment is provided on the outer periphery of the fixed inner cylinder 5, and the load clutch member 7 is screwed to the secondary screw. The load clutch member 7 and the base end of the second sleeve 9 are coupled to each other at the joint portion 40 so as to be relatively rotatable and axially displaceable. The outer periphery of the load clutch member 7 is inserted into the inner periphery (the top surface of the screw) of the primary screw 15 that is a large-diameter screw so as to be capable of relative rotation and axial movement. An axial groove 41 in which the tip of the clutch pawl 13 engages is provided at a position 180 degrees away from the inner periphery of the primary screw 15.
[0029]
The clutch pawl 13 of the load clutch member 7 has the same structure as that of the first embodiment in which the pin 17 is tilted around the pin 17, but the collapse direction is only one direction, and therefore, the compression coil spring 18 holds this in the standing state. Is provided only on one side. A lock pin 38 that holds the clutch pawl in its overturned state (clutch disengaged state) is provided so as to be movable by a predetermined stroke in the axial direction adjacent to each clutch pawl 13, and the lock pin is moved to the tip side, that is, A lock spring 39 that biases toward the first sleeve side is provided. When the lock pin 38 is moved to the front end side by the urging force of the lock spring 39, the inclined lock surface 38a locks the clutch pawl 13 in a lying state, and at this time, the front end of the lock pin 38 is in contact with the load clutch member 7. It protrudes to a surface facing the proximal end of the first sleeve 16 at the distal end. That is, when the proximal end of the first sleeve 16 is in contact with the load clutch member 7, the lock pin 38 cannot move to the distal end side, and therefore the clutch pawl 13 is not locked.
[0030]
When the clutch pawl 13 is in an upright state, the tip of the clutch pawl engages with a concave groove 41 provided on the inner diameter surface of the primary screw 15, and the rotation of the rotating outer cylinder 11 is transmitted to the load clutch member 7. The Rukoto. At this time, since the load clutch member 7 is screwed into the secondary screw 8, the load clutch member 7 moves in the axial direction, and the tip of the clutch pawl 13 moves in the axial direction while being engaged with the concave groove 41. I will do it.
[0031]
At the distal end of the second sleeve 9, there is provided an axially elongated boosting chamber having a width that allows the passive sphere 34 and the pushing sphere 35 to be loosely fitted, and is positioned at the proximal end side and the distal end side of the boosting chamber. Thus, two passive spheres 34 are inserted, and a push-in sphere 35 is inserted between the two passive spheres with the center thereof being biased radially outward from the center of the passive sphere.
[0032]
The distal end of the first sleeve 16 has a cylindrical shape without a notch, but the inner surface on the distal end side is a loosely tapered surface with the distal end side having a large diameter. The pushing sphere 35 is in contact with the conical inner surface 42. Therefore, when the first sleeve 16 moves toward the distal end side relative to the second sleeve 9, the pushing sphere 35 is driven by the wedge action of the conical inner surface 42. It is pushed to the 34 side, and the boost of the direction which separates the two passive spheres 34 and 34 is generated.
[0033]
In the chuck open state, the base end of the first sleeve 16 is in contact with the load clutch member 7. When the rotating outer cylinder 11 is rotated in the forward direction in this state, the load clutch member 7 rotates together with the rotating outer cylinder 11 and moves to the distal end side according to the lead of the secondary screw 8 when no load is applied. The second sleeve 9 also moves. Since the first sleeve 16 is screwed into the primary screw 15 having the same lead as the secondary screw 8 and cannot rotate, the first sleeve 16 moves forward while maintaining a relative positional relationship with the second sleeve 9.
[0034]
When the chuck pawl comes into contact with the workpiece and a load is applied to the pull rod, the load prevents the second sleeve 9 from moving forward. Therefore, a rotational load is applied to the load clutch member 7, and the clutch pawl 13 falls and the clutch is disengaged. . On the other hand, since the rotating outer cylinder 11 continues to rotate, only the first sleeve 16 moves forward with the second sleeve 9 stopped. The proximal end of the first sleeve that moves forward moves away from the clutch member 7, and the lock pin 38 advances to lock the lying state of the clutch pawl 13. By the relative advance of the first sleeve 16, the pushing ball 35 is pushed to generate an axial boost, and this boost pulls the pull rod so that the chuck firmly holds the workpiece.
[0035]
When the rotating outer cylinder 11 is rotated in the reverse direction from this state, only the first sleeve 16 is retracted because the lying state of the clutch pawl 13 is held by the lock pin 38. When the base end of the first sleeve comes into contact with the load clutch member 7, the lock pin 38 is pushed back to release the clutch pawl 13 from being locked. The tip of the clutch pawl and the groove 41 are engaged at a position facing the groove 41. This engaging position is the same position as the position where the tip of the clutch pawl 13 and the groove 41 are disengaged when the chuck is closed. Thereafter, since the load clutch member 7 rotates in synchronization with the rotating outer cylinder 11, the first sleeve 16 and the second sleeve 9 move to the stroke end on the proximal end side while maintaining the relative position.
[Brief description of the drawings]
FIG. 1 is a cross-sectional side view showing only the upper half of the first embodiment in cross section. FIG. 2 is a cross-sectional view of a load clutch portion of the first embodiment. FIG. 4 is a detailed development view of the wedge chamber and the boost chamber of the first embodiment. FIG. 5 is a cross-sectional side view of the main part showing only the upper half of the second embodiment. ] Cross-sectional view of the load clutch portion of the second embodiment [FIG. 7] Vertical cross-sectional view of the load clutch portion of the second embodiment [Explanation of symbols]
5 Fixed inner cylinder 6 Fixed flange 7 Load clutch member 8 Secondary screw 9 Second sleeve
11 Rotating outer cylinder
15 Primary screw
16 First sleeve
20 Axial member
24 Bar nut
25 coupling
32 Booster room
33a Wedge surface
34 Passive sphere
35 Pushing sphere
38 Lock pin

Claims (3)

A primary screw (15) and a secondary screw (8) of the same lead arranged on a concentric cylinder, a load clutch member (7) for transmitting the rotation of the primary screw to the secondary screw, and the primary screw A first sleeve (16) that moves in the axial direction by rotation of the second sleeve, a second sleeve (9) that moves in the axial direction by rotation of the secondary screw, and an axial force member (20 ), A plurality of booster chambers (32) formed at positions that equally divide the circumference between the opposing surfaces of the axial force member and the second sleeve, and are arranged in each booster chamber with an interval in the axial direction. Spherical or cylindrical passive body (34) and a spherical or cylindrical body positioned between the adjacent passive bodies deviating from a line connecting the axial centers of two passive bodies adjacent in the axial direction of each booster chamber A cylindrical pusher (35) and a pusher provided in the peripheral or side surface of the tip of the first sleeve are simultaneously pushed toward the passive body. To a wedge surface (33a), for rotating said primary screw, axial force generator. The load clutch member (7) is screwed into the secondary screw (8), and the load clutch member and the second sleeve (9) are connected so as to be relatively rotatable and immovable in the relative axial direction. A locking body (38) forcibly holding in the disengaged state, and a lock spring (39) for urging the locking body in the clutch disengagement direction, the first sleeve (16) being a load clutch member (7 ) Is moved to the base end side to a position where it abuts against the urging force), the locking body (38) is pushed against the urging force of the lock spring, and the forced disengagement state of the load clutch is released, and the first sleeve is released. The axial force generator according to claim 1, wherein when the spring is separated from the load clutch member, the lock spring forcibly holds the clutch disengaged state by pushing the locking body. A fixed inner cylinder (5) having a fixing flange (6) at the base end and a rotating outer cylinder (11) positioned outside the fixing inner cylinder (5) are provided, and the primary screw is provided on the inner peripheral surface of the rotating outer cylinder. The axial force generating device according to claim 1 or 2 is provided between the fixed inner cylinder and the rotating outer cylinder, and the pulling rod is inserted into the center hole of the fixed inner cylinder at the tip of the axial force member (20). A mechanical chuck cylinder provided with a coupling tool (24, 25).

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