JP4179431B2 - Work gripping device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a workpiece gripping device used in a machine tool such as a lathe.
[0002]
[Prior art]
A workpiece gripping device (also referred to as a chuck) for gripping a workpiece is attached to the tip of the main spindle of the lathe. The workpiece gripping device is provided with a plurality of claw members that are arranged at equal intervals around the rotation axis of the main shaft and are held so as to be movable in the radial direction. The number of claw members is generally three or four.
[0003]
In the workpiece gripping device, it is necessary to move the claw member in the radial direction when the workpiece is attached or detached. There is a workpiece gripping device that is configured so that the operator manually moves the claw member using a tool such as a spanner called a chuck rotator. However, since the attachment and detachment work is troublesome, the claw member is automatically moved. A workpiece gripping device configured as described above is used.
[0004]
For example, a hydraulic cylinder is arranged on the main shaft of a machine tool so that the piston rod moves coaxially with the main shaft, and the axial movement of the piston rod is controlled in the radial direction of the claw member using the lever principle or the wedge principle. There are so-called lever-shaped or wedge-shaped workpiece gripping devices configured to convert to movement. In addition, a spiral guide portion (for example, a groove portion) is formed on the scroll plate disposed on the rear end side of the claw member, and an engaging portion (for example, a protrusion) that engages with the guide portion on the rear end surface of the claw member. There is also a so-called scroll-type workpiece gripping device in which the claw member is moved in the radial direction by rotating the scroll plate with a motor.
[0005]
However, since the workpiece gripping device described above requires a drive source for moving the claw member in addition to the drive source for rotating the main shaft, the configuration of the machine tool including the workpiece gripping device is increased in size. There is a problem that the product cost increases.
[0006]
In view of this, a workpiece gripping and spindle driving device capable of performing rotation driving of the spindle and driving of the claw member with the same driving source is disclosed in Japanese Patent Laid-Open No. Hei 8-19903. FIG. 4 is a cross-sectional view for explaining the above apparatus, (a) is a cross-sectional view of a head stock 41 of a lathe to which the above apparatus is applied, and (b) is a scroll mounted on the main head base 41. 4 is a cross-sectional view of the chuck 40. FIG.
[0007]
In this apparatus, in order to operate the chuck 40 to grasp the workpiece, the hydraulic pressure pressurized from the hydraulic pressure source 42 is introduced from the electromagnetic switching valve 43 to the cylinder 44, the piston 45 is driven, and the gap between the clamp teeth 46 is driven. A positioning pin 47 is inserted and the main shaft 48 is fixed so as not to rotate. The movement of the piston 45 at this time is detected by the proximity switch 49. When the movement of the piston 45 is detected by the proximity switch 49 and the clamp of the main shaft 48 is confirmed, the control device gives a start command to the motor 50 to start, the output shaft 51 is rotated, and the gear 52 is rotated.
[0008]
The annular gear 53 is rotated by the rotation of the gear 52. When the annular gear 53 is rotationally driven, the internal teeth 54 rotationally drive the pinion 55. Since the pinion 55 and the pinion 56 are integral, the internal teeth 57 are rotationally driven by this rotation. The scroll plate 58 is rotated by driving the internal teeth 57, the master jaw 59 is driven in the radial direction by the rotation of the scroll plate 58, and the workpiece is clamped by the soft jaw 60.
[0009]
When the main shaft 48 is driven to rotate, hydraulic pressure is introduced into the cylinder 44 to bring the pinton 45 into an unclamped state and release the main shaft 48. Next, when the motor 50 is activated and rotated in the same direction as when the workpiece is clamped, the chuck 40 rotates with the workpiece (and thus the spindle 48 also rotates), and the workpiece can be cut by the tool post. Become.
[0010]
[Problems to be solved by the invention]
In a general lathe, a drive source such as a motor is disposed on the rear end side of the main shaft, and power is transmitted from the rear end side using a transmission mechanism composed of a plurality of gears, for example, to drive the main shaft to rotate. ing. On the other hand, in the workpiece gripping and spindle driving device described above, the motor 50 is disposed on the side of the spindle 48 and power is transmitted from the tip end side using a transmission mechanism including an annular gear 53 and the like to cause the spindle 48 to move. It is driven to rotate. Therefore, if it is intended to apply the workpiece gripping and spindle driving device to an existing lathe, the entire spindle head must be changed, resulting in an increase in manufacturing cost and inferior versatility.
[0011]
The present invention has been made to solve the above-described conventional drawbacks, and an object of the present invention is to provide a workpiece gripping device that can be used by being mounted on a spindle of an existing machine tool to improve versatility. It is to provide.
[0012]
[Means and effects for solving the problems]
Accordingly, the workpiece gripping device according to the first aspect is attached to the main body 12 coaxially attached to the main shaft 3 of the machine tool 2 that can be driven forward and backward, and to the main body 12 so as to be rotatable about the axis 3a of the main shaft 3. In addition, a holding member 15 that holds a plurality of claw members 19, 19 arranged at equal intervals around the axis 3 a at a distal end thereof, and that can be moved in the radial direction, and more than a distal end portion of the holding member 15 The scroll member 20 is disposed on the rear end side and rotates around the axis 3a in conjunction with the rotation of the main body 12, and the scroll member 20 is spirally wound around the axis 3a on the front end surface. On the other hand, the claw member 19 is formed with an engaging portion 23 to be engaged with the guide portion 22 on the rear end surface facing the scroll member 20. Allow or limit rotation A rotation braking means 29 that, and a connecting and separating means 30 for coupling or separating the said retaining member 15 and the body 12, the connecting and separating means 30, the connecting and separating means 30, connected to the holding member 15 the tubular member 16 which is integrally formed Te, provided with an inner circumferential surface 16b of a tapered structure, such as the outer diameter decreases toward the distal end side, in the main body 12, the outer diameter toward the distal end side A pressure contact surface 31a having a taper structure that becomes smaller is provided, and the holding member 15 and the main body 12 are connected or separated using frictional resistance between the inner peripheral surface 16b and the pressure contact surface 31a. When the claw member 19 is moved in order to grip the holding member 15, the rotation braking means 29 restricts the rotation of the holding member 15 and the connection / separation means 30 When the scroll member 20 is rotated by the rotation of the main shaft 3 in a state separated from the main body 12, while the gripped work W is rotated, the rotation braking means 29 allows the holding member 15 to rotate. In the state where the holding member 15 and the main body 12 are connected by the connecting / separating means 30, the holding member 15 is rotated together with the main body 12 by the rotation of the main shaft 3.
[0013]
In the workpiece gripping device according to the first aspect, when the claw member 19 is moved to grip the workpiece W, the rotation of the holding member 15 is restricted and the holding member 15 and the main body 12 are separated. In this state, when the main shaft 3 is rotated, the main body 12 rotates, but the holding member 15 does not rotate. The scroll member 20 rotates in conjunction with the rotation of the main body 12. The engaging portion 23 of the claw member 19 is engaged with the guide portion 22 of the scroll member 20, and the engaging position of the engaging portion 23 with respect to the guide portion 22 is along the guide portion 22 as the scroll member 20 rotates. Move. Since the claw member 19 is held so as to be movable only in the radial direction, and the guide portion 22 is formed in a spiral shape with the axis 3a as the center, the claw member 19 is moved in the radial direction as the scroll member 20 rotates. Moving. Accordingly, when gripping the workpiece W in the external gripping mode, first, the main shaft 3 is rotated in a specific direction, and the claw member 19 is moved outward in the radial direction. Then, after placing the workpiece W near the center of the tip of the holding member 15, the spindle 3 is rotated in the opposite direction to move the claw member 19 toward the radially inward side, that is, toward the center, thereby gripping the workpiece W. To do. On the other hand, when gripping the workpiece W in the lining mode, the direction of the claw member 19 is reversed from that in the external gripping mode, and the operation is also performed in reverse.
[0014]
On the other hand, when the gripped workpiece W is rotated, the holding member 15 is allowed to rotate and the holding member 15 and the main body 12 are connected. In this state, when the main shaft 3 is rotated, the main body 12 rotates and the holding member 15 also rotates together with the main body 12. Accordingly, the workpiece W held by the holding member 15 also rotates.
[0015]
As described above, the claw member 19 is moved using the rotational force of the main shaft 3 included in the machine tool 2, so that the work W can be gripped and rotated only by mounting the work gripping device on the main shaft 3. Therefore, it can be easily applied to the main spindle 3 of the existing machine tool 2, and a work gripping device having excellent versatility can be realized. In addition, since a dedicated drive source for moving the claw member 19 is not required, it can be configured with a simple structure and can be downsized. Furthermore, since the moving distance of the claw member 19 is increased by enlarging the scroll member 20 and extending the length of the guide portion 22, the range of the outer diameter or inner diameter of the workpiece W that can be gripped by one kind of claw member 19 is increased. Can be enlarged. Further, since the gripping force of the workpiece W by the claw member 19 can be changed by controlling the torque of the main shaft 3, the workpiece W can be gripped with an optimum gripping force. In particular, even a workpiece W that is easily deformed, such as a thin-walled cylindrical part, can be gripped without being deformed by controlling the gripping force and can be centered with high accuracy. Accuracy can be improved.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Next, specific embodiments of the workpiece gripping device of the present invention will be described in detail with reference to the drawings. FIG. 1 is a side sectional view of a workpiece gripping device 1 according to an embodiment of the present invention, FIG. 2 is a front view of the workpiece gripping device 1, and FIG. It is a perspective view which shows a state.
[0021]
As shown in FIG. 3, the workpiece gripping device 1 is used by being attached to the tip of the spindle 3 of the lathe 2. The spindle 3 is installed on the spindle stock 4 and is rotationally driven around the axis 3a by a drive mechanism (not shown). The main shaft 3 is a cylindrical member. A connecting rod 6 is inserted through the main shaft 3, and a rotating cylinder 5 is disposed on the base end side. The rotating cylinder 5 and the connecting rod 6 are connected to each other. Further, a rotary joint 7 is attached to the rear end portion of the rotary cylinder 5, and hydraulic hoses 8 and 8 are connected to the rotary joint 7. Then, hydraulic oil from a hydraulic source (not shown) is supplied to the rotary cylinder 5 via the switching valve 9 and the hydraulic hoses 8 and 8. In response to switching of the operation lever 10 of the switching valve 9, the rotating cylinder 5 moves the connecting rod 6 forward to the front end side or backward to the rear end side.
[0022]
Next, a specific configuration of the workpiece gripping device 1 will be described with reference to FIG. The workpiece gripping device 1 includes a main body 12 that is coaxially attached to a tip end of a main shaft 3 by a plurality of mounting bolts 11. An outer cylinder 14 is attached to the main body 12 using a bearing 13 so as to be rotatable around the axis 12a of the main body 12 (the axis 3a of the main shaft 3). The outer cylinder 14 is integrally configured by connecting a holding member 15 disposed on the distal end side of the main body 12 and a cylindrical member 16 disposed on the proximal end side of the main body 12 by a plurality of fixing bolts 17. Has been.
[0023]
The holding member 15 has a plurality (three in this embodiment) of groove portions 18, 18, and 18 at the tip portion (see FIG. 2). Each groove 18 extends in the radial direction with the line 12a of the main body 12 as the center, and is formed so that its formation direction is equally spaced (120 ° in the present embodiment). And each claw member 19 is fitted in each groove part 18 so that sliding is possible along a longitudinal direction. Accordingly, the holding member 15 holds the three claw members 19 arranged at equal intervals around the axis 12 at the tip thereof so as to be movable in the radial direction.
[0024]
The claw member 19 includes a base jaw 19a fitted in the groove 18 and a top jaw 19b fixed to a front end surface of the base jaw 19a by a mounting bolt (not shown). The top jaw 19b has a plurality of contact surfaces S1 and S2 that are in contact with the workpiece W on the radially inner side. The contact surfaces S1 and S2 are formed at positions where the distances from the axis 12a of the main body 12 are different from each other. Therefore, when gripping the workpiece W, the position in the radial direction of the claw member 19 and the contact surface with which the workpiece W is brought into contact are selected in correspondence with the outer diameter of the workpiece W. Further, by replacing the top jaw 19b with another type, that is, with a position of the contact surface different when fixed to the base jaw 19a, a workpiece W having a larger outer diameter or a workpiece W having a smaller outer diameter is obtained. Can be gripped.
[0025]
Further, on the rear end side of the front end portion of the holding member 15, the scroll member 20 is attached to the front end portion of the main body 12 by a bearing 21 so as to be rotatable around the axis 12 a. The scroll member 20 has scroll teeth 22 which are spiral guides with the axis 12a as the center on the tip surface. On the other hand, on the base jaw 19a of the claw member 19, a plurality of rack teeth 23, 23 engaged with the scroll teeth 22 are formed along the radial direction on the rear end face facing the scroll member 20. Therefore, if the scroll member 20 is rotated in a state where the outer cylinder 14 including the holding member 15 is fixed, the claw member 19 moves in the radial direction.
[0026]
Further, a speed reducer 24 is interposed between the scroll member 20 and the main body 12. Therefore, the scroll member 20 rotates in conjunction with the rotation of the main body 12 at a speed slower than the rotation speed of the main body 12. In the present embodiment, the speed reducer 24 is configured by a harmonic drive (registered trademark). That is, the wave generator 25 serving as the input shaft is fixed to the main body 12, the circular spline 26 serving as the fixed shaft is fixed to the outer cylinder 14, and the flex spline 27 serving as the output shaft is connected to the wave generator 25 and the circular. The splines 26 are respectively engaged with each other and fixed to the rear end side of the scroll member 20 by mounting bolts 28 and 28. Therefore, if the wave generator 25 (main body 12) is rotated while the circular spline 26 (outer cylinder 14) is fixed, the flex spline 27 (scroll member 20) rotates at a slower speed than the wave generator 25. The circular spline 26 is interposed between the holding member 15 and the cylindrical member 16 and is fixed by a fixing bolt 17.
[0027]
A rotation braking means 29 that allows or restricts the rotation of the outer cylinder 14 is disposed on the upper surface 2 a of the lathe 2 and at a position close to the outer peripheral surface of the cylindrical member 16 of the outer cylinder 14. The rotation braking means 29 includes an outer cylinder rotation stop pin 29 a and a pin operation cylinder 29 b that projects or retracts the outer cylinder rotation stop pin 29 a toward the outer peripheral surface of the outer cylinder 14. A concave portion 16a is formed in the outer peripheral portion of the cylindrical member 16, and if the outer cylinder rotation stop pin 29a is fitted in the recess 16a, the rotation of the outer cylinder 14 is restricted, while the outer cylinder rotation stop pin The outer cylinder 14 is allowed to rotate if 29a is extracted from the recess 16a.
[0028]
Further, a connecting / separating means 30 for connecting or separating the outer cylinder 14 and the main body 12 is disposed inside the cylindrical member 16. The connecting / separating means 30 includes a cone brake plate 31, a brake operating connecting member 32, and a brake plate support pin 33 for connecting them. The cone brake plate 31 is disposed in a storage space 34 formed between the main body 12 and the cylindrical member 16, and is inserted in the main body 12 so as to be movable along the main body 12. The surface 31a becomes a pressure contact surface pressed against the outer cylinder 14 (tubular member 16), and the pressure contact surface 31a is inclined so that the outer diameter becomes smaller toward the distal end side. Further, the brake actuating connection member 32 is disposed on the distal end side of the main shaft 3 and in a storage space 35 formed between the main body 12 and the main shaft 3, and at the front end of the connection rod 6 by a mounting bolt 36. Fixed to the part.
[0029]
The brake plate support pins 33, 33 are arranged to extend from the storage space 34 to the storage space 35 in parallel with the axis 12 a and pass through the main body 12. At the end on the storage space 35 side, mounting bolts 38, The brake actuation connecting member 32 is fixed by 38, and the cone brake plate 31 is fixed to the end portion on the storage space 34 side by mounting bolts 37, 37. As a result, the connecting / separating means 30 moves forward or retracts toward the main shaft 3 as the connecting rod 6 advances or retracts. Further, when the main shaft 3 rotates, the connection / separation means 30 rotates integrally with the main body 12.
[0030]
On the other hand, in the cylindrical member 16, the inner peripheral surface 16b facing the pressure contact surface 31a of the cone brake plate 31 is inclined so that the inner diameter becomes smaller toward the tip side, and is tapered between the pressure contact surface 31a. Is made. Therefore, in a state in which the connecting / separating means 30 is advanced and the pressure contact surface 31a of the cone brake plate 31 is pressed against the inner peripheral surface 16b of the cylindrical member 16, the connection / separation means 30 and the outer cylinder are caused by frictional resistance between the pressure contact surfaces. 14 is a state which can rotate integrally. Since the connecting / separating means 30 rotates integrally with the main body 12 as described above, the main body 12 and the outer cylinder 14 rotate integrally. In the state where the connecting / separating means 30 is moved backward and the pressure contact surface 31 a of the cone brake plate 31 is separated from the inner peripheral surface 16 b of the cylindrical member 16, the main body 12 and the outer cylinder 14 are separated.
[0031]
The operation of the workpiece gripping device 1 will be described. First, when gripping the workpiece W, the main shaft 3 is rotated to rotate the workpiece gripping device 1, and the outer cylinder rotation stop pin 29a of the rotation braking means 29 and the concave portion 16a of the cylindrical member 16 are aligned. Later, the outer cylinder rotation stop pin 29a is fitted into the recess 16a to restrict the rotation of the outer cylinder 14, and the connecting / separating means 30 is moved backward toward the main shaft 3 to separate the outer cylinder 14 from the main body 12. In this state, when the main shaft 3 is rotated, the main body 12 rotates, but the outer cylinder 14 does not rotate, and the scroll member 20 rotates in conjunction with the rotation of the main body 12. The rack teeth 23 of the claw member 19 mesh with the scroll teeth 22 of the scroll member 20, and the meshing position of the rack teeth 23 with respect to the scroll teeth 22 moves along the scroll teeth 22 as the scroll member 20 rotates. To do. Since the claw member 19 is held by the outer cylinder 14 so as to be movable only in the radial direction, and the scroll teeth 22 are formed in a spiral shape with the axis 12a of the main body 12 as the center, the claw member 19 is a scroll member. Move in the radial direction according to 20 rotations.
[0032]
Therefore, when gripping the workpiece W, first, the spindle 3 is rotated in a specific direction, and the claw member 19 is moved outward in the radial direction. Then, after placing the workpiece W near the center of the tip of the outer cylinder 14, the spindle 3 is rotated in the reverse direction to move the claw member 19 radially inward, that is, toward the center, and the contact surface. The workpiece W is gripped by bringing S1 or S2 into contact with the outer peripheral surface of the workpiece W. If the outer diameter of the workpiece W is small, the inner contact surface S1 may be used, and if the outer diameter is large, the outer contact surface S2 may be used.
[0033]
On the other hand, when rotating the gripped workpiece W, the outer cylinder rotation stop pin 29a of the rotation braking means 29 is removed from the recess 16a of the cylindrical member 16 to allow the outer cylinder 14 to rotate, and the connection / separation means 30 is moved to the tip. The outer cylinder 14 and the main body 12 are connected by advancing to the side. In this state, when the main shaft 3 is rotated, the main body 12 rotates and the outer cylinder 14 also rotates together with the main body 12. Accordingly, the workpiece W held by the outer cylinder 14 also rotates. Then, a desired cutting process is performed on the workpiece W with a cutting tool (not shown).
[0034]
Note that a speed reducer 24 is interposed between the main body 12 and the scroll member 20, and this speed reducer 24 is constituted by a harmonic drive, and the main body 12 and the outer cylinder 14 are integrated. When rotating, the circular spline 26 serving as a fixed shaft rotates together with the outer cylinder 14, and the wave generator 25 rotates together with the main body 12, and the rotation speed is the same. Therefore, the speed reducer 24 does not function, and the scroll member 20 rotates at the same speed as the outer cylinder 14 and the claw member 19 does not move. Therefore, the workpiece W falls off or an excessive gripping force acts on the workpiece W. There is nothing.
[0035]
As described above, according to the present embodiment, since the claw member 19 is moved using the rotational force of the main shaft 3 provided in the lathe 2, the work W can be simply mounted on the main shaft 3. Can be gripped and rotated. Therefore, it can be easily applied to the main spindle 3 of the existing lathe 2, and the work gripping device 1 having excellent versatility can be realized.
[0036]
In addition, since a dedicated drive source for moving the claw member 19 is not required, it can be configured with a simple structure and can be downsized.
[0037]
Furthermore, since the moving distance of the claw member 19 is increased by increasing the outer diameter of the scroll member 20 and extending the length of the scroll teeth 22, the range of the outer diameter of the work W that can be gripped by one type of top jaw 19a. Can be enlarged. As a result, the types of top jaws prepared in advance corresponding to the outer diameter of the workpiece W are reduced, and the cost can be reduced. Further, the frequency of exchanging the top jaws is reduced, the burden on the operator is reduced, and the work efficiency can be improved.
[0038]
Further, since the gripping force of the workpiece W by the claw member 19 can be changed by controlling the torque of the main shaft 3, the workpiece W can be gripped with an optimum gripping force. In particular, even a workpiece W that is easily deformed, such as a thin-walled cylindrical part, can be gripped without being deformed by controlling the gripping force and can be centered with high accuracy. Can be improved.
[0039]
Further, since the rotary cylinder 5 provided in advance in the lathe 2 is used as a drive source for the connecting / separating means 30, there is almost no need to modify the lathe 2 side and the work gripping device 1 can be applied at low cost. it can. Further, by using the rotary cylinder 5 on the lathe 2 side, the configuration of the workpiece gripping device 1 can be simplified, reduced in size, and reduced in weight.
[0040]
Further, since the scroll member 20 is rotated at a speed slower than the rotation speed of the main shaft 3 (main body 12), the scroll member 20 is rotated by a control amount smaller than the minimum control amount of the rotation angle of the main shaft 3 of the lathe 2. Since the angle can be controlled, the positioning accuracy when the claw member 19 is moved can be improved. This is effective when gripping the workpiece W.
[0041]
A speed increaser may be used instead of the speed reducer 24. In this case, since the scroll member 20 rotates at a speed faster than the rotation speed of the main body 12, the claw member 19 can be moved quickly. This is effective when the workpiece W is removed.
[0042]
Although the present embodiment describes an aspect in which the workpiece W is gripped externally, when the workpiece W is lined, the direction of the claw member 19 (top jaw) is reversed, and the operation is reverse to that of the external grip. Thus, a lining is obtained. Needless to say, the same effect as the outer grip can be obtained.
[Brief description of the drawings]
FIG. 1 is a side sectional view of a workpiece gripping apparatus according to an embodiment of the present invention.
FIG. 2 is a front view of the workpiece gripping device.
FIG. 3 is a perspective view showing a state in which the workpiece gripping device is mounted on a lathe.
4A and 4B are cross-sectional views showing a conventional technique, in which FIG. 4A shows a headstock of a lathe, and FIG. 4B shows a scroll chuck.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Work holding device 2 Lathe 3 Main axis 3a Axis 5 Rotating cylinder 6 Connecting rod 12 Main body 12a Axis 14 Outer cylinder 15 Holding member 16 Cylindrical member 16a Recess 19 Claw member 20 Scroll member 22 Scroll tooth 23 Rack tooth 24 Reduction gear 25 Wave generator 26 Circular spline 27 Flex spline 29 Rotation braking means 29a Outer cylinder rotation stop pin 29b Pin operation cylinder 30 Connection separation means 31 Cone brake plate 32 Brake operation connection member 33 Brake plate support pin W Workpiece

Claims (1)

A main body (12) attached coaxially to a main shaft (3) of a machine tool (2) capable of forward / reverse driving, and a main body (12) which is rotatable about an axis (3a) of the main shaft (3). And a holding member (15) for holding a plurality of claw members (19, 19) arranged at equal intervals around the axis (3a) at the front end portion thereof so as to be movable in the radial direction. A scroll member (20) disposed on the rear end side of the front end portion of the holding member (15) and rotating about the axis (3a) in conjunction with the rotation of the main body (12); The member (20) is formed with a spiral guide portion (22) centered on the axis (3a) on the front end surface, while the claw member (19) has a rear surface facing the scroll member (20). An engaging portion (23) to be engaged with the guide portion (22) is formed on the end surface. Furthermore, a rotation braking means (29) for allowing or restricting the rotation of the holding member (15), and a connecting / separating means (30) for connecting or separating the holding member (15) and the main body (12) are provided. The connecting / separating means (30) has a tapered structure in which the outer diameter decreases toward the distal end side of the cylindrical member (16) integrally connected to the holding member (15). with the inner peripheral surface (16b) provided in said body (12), contact face of a tapered structure so that the outer diameter becomes smaller (31a) provided towards the distal end side, a contact face the inner peripheral surface (16b) The holding member (15) and the main body (12) are connected or separated using frictional resistance with (31a), and the claw member (19) is moved to grip the workpiece (W). When making the rotation braking The means (29) restricts the rotation of the holding member (15), and the connecting / separating means (30) separates the holding member (15) and the main body (12) from the main shaft (3). When rotating the scroll member (20) by rotation while rotating the gripped work (W), the rotation braking means (29) allows the holding member (15) to rotate and the connection / separation means. The holding member (15) is rotated together with the main body (12) by rotating the main shaft (3) in a state where the holding member (15) and the main body (12) are connected in (30). A workpiece gripping device characterized by the above.

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