TWI577511B - Chuck - Google Patents

Description

Chuck

The present invention relates to a collet for holding a workpiece.

As a chuck for gripping a workpiece, a chuck is known which grips a workpiece by a pair of grip portions. In a typical collet, a pair of grip portions are slidably supported on the collet body in the opening and closing direction. A drive mechanism for driving a pair of gripping portions is a combination of a rotary motor and a gear mechanism. However, this typical chuck has a problem that the opening and closing speed is slow and the miniaturization is difficult.

In order to solve this problem, Patent Document 1 discloses a chuck in which a cylinder and a link mechanism are used instead of a rotary motor and a gear mechanism as a drive mechanism for driving a pair of grip portions. The chuck has a cylinder chamber and a piston that moves linearly in the cylinder chamber. A guide rail extending in a direction orthogonal to a moving direction of the piston is fixed to the cylinder chamber. The guide rail guides the pair of grip portions to move the grip portion in the opening and closing direction. A link mechanism is disposed between the piston and the pair of grips. The link mechanism is configured to open the pair of grip portions when the piston moves in a direction protruding from the cylinder chamber, and close the pair of grip portions when the piston moves in the direction of entering the cylinder chamber.

[Previous Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open Publication No. 2011-212754

In recent years, in order to reduce the production cycle time of the work, it is desirable to reduce the size and speed of the chuck. In the chuck described in Patent Document 1, since the linear motion of the piston is converted into the opening and closing operation of the grip portion by using the link mechanism, there is an advantage that the grip portion can be opened and closed at a high speed. However, if it is desired to ensure the opening and closing stroke of the grip portion, there is a problem that it is difficult to downsize the chuck.

Accordingly, it is an object of the present invention to provide a chuck that can be reduced in size and speed.

In order to solve the above problems, a chuck according to the present invention includes a drive source including a main body portion and a movable portion movable in a straight line with respect to the main body portion, and an arm coupled to the movable portion a support portion fixed to the body portion; a pair of holding links having a first portion and a second portion connected in an L shape, the bent portion being rotatably supported by the support via the rotating shaft And a pair of gripping portions disposed on the first portion of the pair of gripping links for gripping the workpiece; and a pair of intermediate links, one end portion thereof Rotatablely coupled to the arm, and the other end is rotatably coupled to the second portion of the pair of gripping links; the first portion of the pair of gripping links is from a more parallel state a state in which the opening is rotated in the closing direction to clamp the workpiece, and the first link rotating shaft of the pair of intermediate links of the arm is viewed from the axial direction of the rotating shaft And a second link rotation axis of the pair of intermediate links of the pair of gripping links is disposed outside the support portion.

According to the invention, since the curved portion of the pair of L-shaped holding links is disposed toward the inner side, and the curved portion is rotatably supported by the supporting portion via the rotating shaft, the opening angle of the pair of holding portions can be ensured. To achieve miniaturization of the chuck. The linear motion of the movable portion is converted into the opening and closing of the grip portion by using the link mechanism Therefore, the grip portion can be opened and closed at a high speed.

(1) ‧‧‧Closed direction

1‧‧‧Linear motor (driver source)

2‧‧‧ linkage mechanism

3‧‧‧Drive shaft (movable part)

4a, 4b‧‧‧ claws (holding department)

11‧‧‧ Body Department

12‧‧‧ tube

13‧‧‧ magnet

14‧‧‧Magnetic pole block

15‧‧‧ coil

16‧‧‧Coil holder

17‧‧‧Substrate

18‧‧‧Shell

19‧‧‧End components

20‧‧‧ sensor

21‧‧‧ bushing

24‧‧‧arm

24a‧‧ hole

25a, 25b, 25a’, 25b’‧‧‧ intermediate links

26a, 26b, 26a’, 26b’‧‧‧ holding the connecting rod

27a, 27b‧‧‧Rotary axis

28, 28'‧‧‧ Cover (support)

28a, 28b‧‧‧Covering

28c‧‧‧ bottom wall

28a1, 28b1‧‧ ‧ gap

31‧‧ ‧ retaining ring

41‧‧‧ Holding the first part of the connecting rod

42‧‧‧ Holding the second part of the connecting rod

43, 43'‧‧‧ Holding the bent part of the connecting rod

44, 44'‧‧‧ first link rotation axis

45, 45'‧‧‧second link rotation axis

47‧‧ ‧ retaining ring

48‧‧ ‧ retaining ring

a, b‧‧‧ length

H‧‧‧ Height

L1, L2, L1', L2'‧‧‧ lines

P1, P1’‧‧‧ spacing

W‧‧‧Width

θ‧‧‧Open angle

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of a collet according to an embodiment of the present invention.

Fig. 2 is a perspective view (including a partial cross-sectional view) of the linear motor of the chuck of the embodiment.

Fig. 3 is a detailed view of the link mechanism of the chuck of the embodiment.

Fig. 4 is a view showing the opening and closing operation of the chuck of the embodiment (Fig. 4(a) shows the chuck which is fully opened, Fig. 4(b) shows the chuck at the stage of starting the closing, and Fig. 4(c) shows the fully closed. Chuck).

Fig. 5 is a view comparing the sizes of the link mechanisms in the present embodiment and the comparative example (Fig. 5(a) and Fig. 5(c) show a comparative example in which the grip link is formed in a straight line, Fig. 5(b) This embodiment is shown in which the grip link is formed in an L shape.

Fig. 6 is a view showing the comparison of the sizes of the link mechanisms in the present embodiment and the comparative example (Fig. 6(a) and Fig. 6(c) show a comparative example in which the grip link is formed in a straight line, Fig. 6(b) This embodiment is shown in which the grip link is formed in an L shape.

Fig. 7 is a view showing a comparison of the sizes of the link mechanisms in the present embodiment and the comparative example (Fig. 7 (a-1) and Fig. 7 (a-2) show a comparative example in which the curved portion of the grip link is directed outward. Fig. 7(b) shows the present embodiment in which the curved portion of the grip link is directed inward.

Fig. 8 is a view showing a comparison of the sizes of the stacked chucks in the present embodiment and a comparative example (Fig. 8(a-1) shows a front view of a comparative example, and Fig. 8(a-2) shows a side view of a comparative example, 8(b-1) shows a front view of the embodiment, and Fig. 8(b-2) shows a side view of the embodiment.

Fig. 9 is a front view showing another example of the chuck of the embodiment.

Hereinafter, a chuck according to an embodiment of the present invention will be described in detail based on the drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of a collet according to an embodiment of the present invention. The chuck of the present embodiment includes a linear motor 1 as a drive source, and a pair of right and left claws 4a and 4b as gripping portions for holding a workpiece. The drive shaft 3 as the movable portion of the linear motor 1 is disposed in the vertical direction. A link mechanism 2 is provided below the linear motor 1. When the drive shaft 3 of the linear motor 1 is linearly moved, the claws 4a and 4b are opened and closed by the link mechanism 2. Hereinafter, the configuration of the linear motor 1 and the link mechanism 2 will be described in order.

As shown in FIG. 2, the linear motor 1 includes a main body portion 11 and a drive shaft 3. The drive shaft 3 includes a hollow tube 12 and a plurality of magnets 13 housed in the hollow space of the tube 12. The magnet 13 is formed in a cylindrical shape and magnetized in the axial direction. The magnets 13 are arranged such that the same poles face each other. A magnetic pole block 14 containing, for example, a magnetic material such as iron is interposed between the magnets 13. An N pole and an S pole are alternately formed in the axial direction of the drive shaft 3 by the magnet 13 and the magnetic pole block 14.

The drive shaft 3 is surrounded by a plurality of coils 15 arranged in the axial direction. A magnetic gap is interposed between the drive shaft 3 and the coil 15. The coil 15 is composed of a three-phase coil including a U ̇ V ̇ W phase. The coil 15 is held by the coil holder 16. A substrate 17 for wiring the coil 15 is disposed on the coil holder 16. The coil 15, the coil holder 16, and the substrate 17 are covered by a resin molded outer casing 18. The coil 15, the coil holder 16, the substrate 17, and the outer casing 18 constitute the body portion 11 of the linear motor 1.

Terminal members 19 are provided at both ends of the outer casing 18 in the axial direction. A sensor 20 (see FIG. 1) for detecting the position of the drive shaft 3 is attached to the terminal member 19. The terminal member 19 is also mounted with a bushing 21 that guides the drive shaft 3 to move in the axial direction.

When the three-phase alternating current flows through the coil 15 of the main body portion 11, by the interaction between the magnetic field generated by the drive shaft 3 and the current flowing through the coil 15, a thrust is generated in the axial direction on the drive shaft 3, so that the drive shaft 3 is on the shaft. Move to. The linear motor 1 of the present embodiment has a small and light feature. By attaching the link mechanism 2 to the linear motor 1, a small and light chuck can be obtained.

The configuration of the link mechanism 2 is as follows. As shown in Fig. 1, the link mechanism 2 includes an arm 24 coupled to the front end of the drive shaft 3 of the linear motor 1, and a pair of intermediate links 25a and 25b rotatably coupled to both ends of the arm 24; The ground link is connected to one of the intermediate links 25a, 25b, and the pair of claws 4a, 4b are attached to the pair of grip links 26a, 26b. The grip links 26a and 26b are rotatably supported by the cover body 28 as a support portion via the rotation shafts 27a and 27b. The arm 24, the pair of intermediate links 25a and 25b, the pair of holding links 26a and 26b, and the pair of claws 4a and 4b are bilaterally symmetrical with respect to the center line of the drive shaft 3.

As shown in FIG. 3, the arm 24 is elongated in a direction orthogonal to the drive shaft 3. Intermediate links 25a and 25b are coupled to both end portions of the arm 24 in the longitudinal direction. A hole 24a into which the front end portion of the drive shaft 3 is inserted is opened at a central portion in the longitudinal direction of the arm 24. The arm 24 is fixed to the front end of the drive shaft 3 by a fastening means such as a fixing bolt, a rivet or the like.

The cover body 28 includes a bottom wall 28c fixed to the main body portion 11 of the linear motor 1, and a pair of facing walls 28a and 28b which are orthogonal to the bottom wall 28c and are parallel to each other. The covering walls 28a, 28b are formed in a rectangular shape. The cover walls 28a, 28b cover a portion of the arm 24 and a portion of the grip links 26a, 26b. The covering walls 28a and 28b support both end portions of the rotating shafts 27a and 27b of the gripping links 26a and 26b. Through-holes through which the rotating shafts 27a and 27b are inserted are opened in the covering walls 28a and 28b. In order to prevent the axial movement of the rotating shafts 27a, 27b, in rotation A retaining ring 31 is fitted to both ends of the shafts 27a and 27b.

The grip links 26a, 26b have a first portion 41 and a second portion 42 that are connected in an L shape. The first portion 41 and the second portion 42 are formed in a straight line shape. The first portion 41, which is the front end side of the gripping links 26a and 26b, is detachably attached to the claws 4a and 4b as gripping portions by a coupling means such as a bolt. The intermediate links 25a and 25b are rotatably coupled to the second end portion 42, which is the base end side of the L-shaped holding links 26a and 26b. Further, the angle between the first portion 41 and the second portion 42 of the L-shape is set to 70 to 110 degrees in the present embodiment, but may be set to any angle less than 180 degrees depending on design conditions. Further, in the present embodiment, the claws 4a and 4b and the gripping links 26a and 26b are separately provided as individual members, but the claws 4a and 4b and the gripping links 26a and 26b may be integrally provided.

The curved portion 43 of the grip links 26a and 26b is rotatably supported by the cover 28 via the rotating shafts 27a and 27b. The pair of grip links 26a and 26b are disposed such that the curved portion 43 faces inward. That is, as shown in FIG. 3, when the claws 4a, 4b are in the fully open position, the pair of holding links 26a, 26b are closest to each other at the curved portion 43.

One end of the intermediate link 25a, 25b is rotatably coupled to the end of the arm 24 via the first link rotating shaft 44, and the other end is rotatably coupled to the holding link 26a via the second link rotating shaft 45. The second part 42 of 26b. The intermediate links 25a, 25b are formed in a U-shaped cross section. The first link rotating shaft 44 passes through the intermediate link 25a or 25b and the arm 24, and the axial movement is prevented by the retaining ring 47. Here, the portion of the first link rotating shaft 44 to which the retaining ring 47 is attached is referred to as both end portions of the first link rotating shaft 44 in the direction of the rotating shaft. The second link rotating shaft 45 passes through the intermediate link 25a or 25b and the holding link 26a or 26b, and the axial movement is prevented by the retaining ring 48. Here, the portion of the second link rotating shaft 45 to which the retaining ring 48 is attached is referred to as the second link rotating. Both ends of the shaft 45 in the direction of the rotation axis.

When viewed from the axial direction of the rotating shafts 27a and 27b, the second link rotating shaft 45 of the intermediate links 25a and 25b is disposed on a line L1 that is closer to the first link rotating shaft 44 and the rotating shafts 27a and 27b. L2 is further outside (incorrectly, Fig. 7(b) shows a front view of the intermediate links 25a, 25b when viewed from the axial direction of the rotating shafts 27a, 27b). This is because when the drive shaft 3 of the linear motor 1 is lowered, the grip links 26a, 26b are closed and the workpiece is held by the claws 4a, 4b. With this configuration, even when the power supply of the coil 15 of the linear motor 1 is cut and the drive shaft 3 is dropped by its own weight, since the grip links 26a and 26b are closed, the claws 4a of the gripping links 26a and 26b are held. The workpiece held by 4b will not fall, and there will be no damage to the workpiece.

As shown in FIG. 3, the first link rotating shaft 44 and the second link rotating shaft 45 of the intermediate links 25a and 25b are disposed on the outer side of the cover 28. When the claws 4a, 4b are in the fully open position (refer to Fig. 4 (a)), or when the claws 4a, 4b are in the fully closed position (refer to Fig. 4 (c)), the first link rotating shaft 44 and the second link are rotated. The shafts 45 are disposed on the outer side of the cover body 28 and do not overlap the cover body 28 in the axial direction. As shown in Fig. 3, the first link rotating shaft 44 and the second link rotating shaft 45 of the intermediate links 25a, 25b protrude further in the axial direction than the intermediate links 25a, 25b. By disposing the first link rotating shaft 44 and the second link rotating shaft 45 on the outer side of the cover body 28, the first link rotating shaft 44 and the second link rotating shaft 45 are not in the rotating axial direction with the cover body. The overlap of 28 reduces the thickness of the cover 28 (thickness in the direction orthogonal to the plane of the paper of Fig. 3). Further, in the present embodiment, not only the first link rotating shaft 44 and the second link rotating shaft 45 but also the intermediate links 25a and 25b are disposed outside the cover 28, but the intermediate link can also be used. One of the portions 25a, 25b overlaps the cover 28.

Figure 4 shows the opening and closing action of the chuck. Figure 4 (a) shows the fully open chuck, Fig. 4(b) shows the chuck at the stage of starting the closing, and Fig. 4(c) shows the chuck with the full closing. As shown in Fig. 4(a), when the drive shaft 3 of the linear motor 1 is the most ascending, the arm 24 is at the most raised position, and the claws 4a, 4b of the grip links 26a, 26b are at the fully open position.

As shown in Fig. 4(b), when the drive shaft 3 of the linear motor 1 is lowered, the arm 24 is also lowered. The intermediate links 25a, 25b connected to both ends of the arm 24 are also lowered together with the arm 24. As the intermediate links 25a, 25b descend, the grip links 26a, 26b rotate in the closing direction (1).

As shown in FIG. 4(c), when the drive shaft 3 of the linear motor 1 is further lowered, the arm 24 and the intermediate links 25a and 25b are further lowered, and the grip links 26a and 26b are further rotated in the closing direction. The grip links 26a, 26b are rotated until the claws 4a, 4b are in contact with each other.

With reference to Fig. 5, the reason why the link mechanism 2 is reduced in size by forming the grip links 26a and 26b into an L shape will be described. 5(a) and 5(c) show a comparative example in which the grip links 26a' and 26b' are formed in a straight line, and Fig. 5(b) shows the embodiment in which the grip links 26a and 26b are formed in an L shape. . In these figures, in order to match the design conditions, the opening amount of the gripping links 26a, 26b and the multiple force of the gripping links 26a, 26b (the length α and the spin from the second link rotating shaft 45 to the rotating shaft 27b) The ratio of the length of the shaft 27b to the length β of the front end portion of the grip link 26b is set to 1. Further, when the drive shaft 3 of the linear motor 1 is lowered, the grip links 26a, 26b are closed.

As shown in the comparative example of Fig. 5 (a), when the grip links 26a' and 26b' are formed in a straight line, if the width W of the link mechanism 2 is to be narrow, the height H becomes long. . As shown in the comparative example of FIG. 5(c), if the height H of the link mechanism 2 is to be short, the width W is widened. As shown in Fig. 5(b), by forming the grip links 26a, 26b in an L shape, the height H and the width W of the link mechanism 2 can be reduced.

Fig. 6 is a view showing the setting of the multiple force of the holding links 26a, 26b (the ratio of the length α from the second link rotating shaft 45 to the rotating shaft 27b to the length β of the front end portion of the holding link 26b from the rotating shaft 27b) For the example of 1.5. Similarly to Fig. 5(b), Fig. 6(b) shows the present embodiment in which the holding links 26a and 26b are formed in an L shape. Similarly to Figs. 5(a) and 5(c), Fig. 6(a) and Fig. 6(c) show a comparative example in which the grip links 26a' and 26b' are formed in a straight line shape.

When the multiple force of the gripping links 26a and 26b is set to 1.5, the distance by which the gripping links 26a and 26b are moved becomes long, but according to the principle of the lever, a force of 1.5 times can be obtained. As shown in FIG. 6(b), by setting the grip links 26a and 26b in an L shape, the height and width of the link mechanism 2 can be reduced when the double force is set to 1.5.

Referring to Figure 7, by bending a pair of holding links 26a, 26b The reason why the portion 43 is oriented toward the inside to reduce the size of the link mechanism 2 will be described. 7(a-1) and 7(a-2) show a comparative example in which the curved portions 43' of the grip links 26a' and 26b' are directed outward, and Fig. 7(b) shows the gripping links 26a, 26b. The present embodiment in which the curved portion 43 faces inward.

As shown in the comparative example of Fig. 7 (a-1), when the curved portions 43 of the pair of holding links 26a' and 26b' are arranged to face outward, the second links 25a', 25b' are second. The link rotating shaft 45' is easily disposed on the inner side with respect to the lines L1' and L2' connecting the first link rotating shaft 44' and the rotating shafts 27a' and 27b' of the intermediate links 25a' and 25b'. Therefore, when the drive shaft 3 is lowered, the grip links 26a' and 26b' are opened. In order to avoid this, as shown in Fig. 7 (a-2), when the second link rotating shaft 45' of the intermediate links 25a', 25b' is disposed outside with respect to the lines L1', L2', the width is The direction causes the link mechanism 2 to be enlarged.

As shown in Fig. 7(b), by bending a pair of holding links 26a, 26b The curved portion 43 is disposed toward the inner side, and the second link rotating shaft 45 of the intermediate links 25a and 25b is easily disposed on the line L1 connecting the first link rotating shaft 44 and the rotating shafts 27a and 27b of the intermediate links 25a and 25b. The outer side of L2 can achieve miniaturization of the link mechanism 2.

Further, as shown in FIG. 7(b), by opening the curved portions 43 of the grip links 26a and 26b toward the inner side, the opening angle θ of the grip links 26a and 26b can be increased. When the gripping links 26a, 26b in the opening are rotated in the closing direction, since the first portions 41 of the gripping links 26a, 26b are brought close to each other, the workpiece is easily gripped.

Fig. 8 is a view showing the comparison of the sizes of the chucks in the present embodiment and comparative examples. 8(a-1) and 8(a-2) show a comparative example in which the first and second link rotating shafts 44' and 45' are disposed inside the cover 28', and Fig. 8(b-1) 8(b-2) shows that the first and second link rotating shafts 44, 45 are disposed on the outer side of the cover body 28, and the first and second link rotating shafts 44, 45 are not overlapped with the cover body 28. Implementation form.

As shown in the front view of the chuck of the comparative example of Fig. 8 (a-1), in the case where the first and second link rotating shafts 44', 45' are disposed inside the cover 28', it is necessary to cover the cover. The thickness of the body 28' (thickness in the direction orthogonal to the plane of the paper of Fig. 8(a-1)) is set to be thicker than the axial lengths of the first and second link rotating shafts 44', 45'. As shown in the side view of the laminated chuck of Fig. 8 (a-2), it is also necessary to increase the pitch P1' in the thickness direction between the chucks (the left-right direction of the paper surface of Fig. 8 (a-2)).

On the other hand, as shown in the front view of the chuck of this embodiment of FIG. 8(b-1), the first and second link rotating shafts 44 and 45 are disposed on the outer side of the cover body 28, first and second. When the two-link rotating shafts 44 and 45 do not overlap the cover 28 in the direction of the rotating shaft, the thickness of the cover 28 (the thickness in the direction orthogonal to the plane of the paper of FIG. 8(b-1)) can be reduced to The axial lengths of the first and second link rotating shafts 44, 45 are below. As shown in the side view of the laminated chuck of Figure 8(b-2), the thickness direction between the chucks can also be reduced (Fig. 8(b-2)). The pitch P1 of the left and right direction of the paper surface.

Figure 9 shows another example of a linkage mechanism. In the present embodiment, in order to further reduce the size of the link mechanism in the width direction, the length of the arm 24 is shortened. Further, the cover walls 28a and 28b of the cover body 28 are formed with notches 28a1 and 28b1, and the cover walls 28a and 28b are formed in an I shape as a whole. By forming the notches 28a1 and 28b1 by the covering walls 28a and 28b of the cover 28, the first and second link rotating shafts 44 and 45 of the intermediate links 25a and 25b are disposed on the outer sides of the covering walls 28a and 28b. Since the first and second link rotating shafts 44, 45 do not overlap the covering walls 28a, 28b in the direction of the rotating shaft, the thickness of the link mechanism (thickness in the direction orthogonal to the plane of the paper of Fig. 9) can be reduced.

The present invention is not limited to the specific embodiments described above, and other embodiments may be embodied without departing from the spirit and scope of the invention.

For example, in the above embodiment, a cylindrical linear motor that surrounds the coil around the drive shaft is used as the drive source, but the structure of the linear motor is not limited to the above embodiment. As the driving source, a flat type linear motor in which a coil is opposed to a permanent magnet via a gap may be used.

In the above embodiment, when the drive shaft of the linear motor is lowered, the grip link is closed. However, if the drive shaft of the linear motor is lowered, the drive link may be opened.

In the above embodiment, a linear motor is used as the drive source, but a cylinder such as a pneumatic cylinder, a hydraulic cylinder, or an electric cylinder may be used as the drive source.

In the above embodiment, the example in which the drive shaft of the linear motor is disposed in the vertical direction has been described. However, the drive shaft of the linear motor may be disposed in any direction such as the horizontal direction.

In the above embodiment, the first and second links of the pair of intermediate links Although the both ends of the rotating shaft are not overlapped with the cover in the direction of the rotation axis, at least one end of the rotation axis direction of the first link rotation axis of at least one of the pair of intermediate links is provided. And/or at least one end of the pair of intermediate links in the direction of the rotation axis of the second link rotating shaft of at least one of the pair of holding links may not overlap the cover in the direction of the rotation axis. That is, the both ends of the first and second link rotating shafts are all eight, but only one of them does not overlap the cover in the direction of the rotating shaft.

The present specification is based on Japanese Patent Application No. 2013-273023 filed on Dec. 27, 2013. The contents are all included in this specification.

4a, 4b‧‧‧ claws (holding department)

11‧‧‧ Body Department

24‧‧‧arm

24a‧‧ hole

25a, 25b‧‧‧ intermediate link

26a, 26b‧‧‧ holding the connecting rod

27a, 27b‧‧‧Rotary axis

28‧‧‧ Cover

28a, 28b‧‧‧Covering

28c‧‧‧ bottom wall

31‧‧ ‧ retaining ring

41‧‧‧ Holding the first part of the connecting rod

42‧‧‧ Holding the second part of the connecting rod

43‧‧‧ Holding the bent part of the connecting rod

44‧‧‧First link rotating shaft

45‧‧‧Second link rotating shaft

47, 48‧‧ ‧ retaining ring

L1, L2‧‧‧ line

Claims (3)

A chuck comprising: a drive unit having a body portion and a movable portion movable in a straight line with respect to the body portion; an arm coupled to the movable portion; and a support portion fixed In the main body portion; a pair of holding links having a first portion and a second portion connected in an L shape, the bending portion being rotatably supported by the support portion via the rotating shaft, and the bending portion Arranging toward the inner side; a pair of gripping portions provided at the first portion of the pair of gripping links for gripping the workpiece; and a pair of intermediate links each of which is rotatably coupled And the other end is rotatably coupled to the second portion of the pair of gripping links; the first portion of the pair of gripping links is open from a more parallel state toward the closing direction Rotating and holding the workpiece, the first link rotating shaft of the pair of intermediate links of the arm, and the pair of holdings for the pair when viewed from the axial direction of the rotating shaft The second link rotating shaft of the pair of intermediate links of the rod is disposed on the outer side of the support portion. The collet of claim 1, wherein the pair of gripping links are closed while the movable portion of the driving source is moving in a direction protruding from the main body portion, and the pair of gripping When the workpiece is clamped, when viewed from the axial direction of the rotating shaft, the second link rotating shaft of the pair of intermediate links of the pair of gripping links is arranged in a relatively connected manner Targeting on The first link rotating shaft of the pair of intermediate links of the arm is further outward than the line of the rotating shaft. The collet of claim 1 or 2, wherein the support portion is provided with one end portion supporting the rotating shaft and covering at least a portion of the arm and at least a portion of the pair of holding links Against the wall.