Chuck device

Abstract

To simplify work when gripping force of workpiece is switched, and prevent gripping of workpiece from loosened by a gripping claw accompanying centrifugal force.SOLUTION: A chuck device includes a draw bar 8 moving forward and backward in an axial direction of a central axis 6 of a chuck body 1, a jaw actuator 10 swingably supported on the chuck body 1, a gripping part 15 provided on a front end of the jaw actuator 10, an engagement projection 13 provided on a rear end 11 of the jaw actuator 10, and an engagement recess 5 that is provided on the outer periphery of the draw bar 8 and with which the engagement projection 13 is engaged, wherein the engagement projection 13 is movable in a radial direction with respect to the engagement recess 5, the engagement projection 13 is pressed in the axial direction by moving the draw bar 8 forward and backward in the axial direction and thereby the jaw actuator 10 is swung in a radial direction and workpiece W is gripped by the gripping part 15, the jaw actuator 10 has a weight 20 on the rear end 11, and the weight 20 is energized toward the front axial direction with respect to the chuck body 1 by energization means 30.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a rocking retracting chuck device.

Background Art

[0002] In a general rocking retracting chuck, as shown in Patent Documents 1 and 2, for example, a plurality of sets of link actuators are arranged at equal azimuths around the central axis of the chuck body on the front surface of the chuck body. A gripping claw for gripping a workpiece is provided at the front end of each link actuator.

[0003] In the middle of each link actuator, a spherical portion having a spherical outer surface is provided. A rocking shaft orthogonal to both the central axis of the chuck body and the chuck radial direction is inserted through the spherical portion. The link actuator is supported so as to be rockable with respect to the chuck body with the rocking shaft as the rocking center. Further, the rear end portion of each link actuator is inserted into the support hole of the actuator flange through a support member having a spherical outer periphery called a sliding ball, and the spherical inner periphery of the support hole and the spherical outer periphery of the support member are engaged with each other so that both are slidably connected.

[0004] The actuator flange can be advanced and retracted in the axial direction along the central axis of the chuck by a drawbar connected to the center of the chuck body. As the actuator flange advances and retracts in the axial direction and the engaged spherical surfaces slide, the rear end portion of each link actuator is operated around the rocking shaft, and the link actuator is rocked in the radial direction of the chuck body. By this rocking, the gripping claws attached to the front end portions of the respective link actuators can grip the workpiece with an equal force and with the axis of the workpiece aligned with the central axis of the chuck body. This type of chuck device is generally referred to as a centering chuck because it is used for the purpose of gripping a workpiece with the axis of the workpiece aligned with the central axis of the chuck body.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In a conventional swing-in type chuck device, when changing the strength of the force for gripping a workpiece, it is necessary to re-grasp the workpiece. Specifically, when switching the gripping force of the workpiece from high pressure to low pressure, the gripping of the workpiece is once released to release the locking action generated in a jaw actuator or the like, and then the workpiece is re-grasped with a desired gripping force. Such re-grasping work is complicated and also leads to an increase in the working time. In the case of switching to increase the force from low pressure to high pressure, since the gripping force can be increased as it is without releasing the locking action, generally re-grasping is not required.

[0007] Further, in a conventional swing-in type chuck device, due to the centrifugal force associated with the high-speed rotation of the chuck, the grip of the workpiece by the gripping jaws may become loose. This phenomenon tends to be particularly prominent when using particularly high gripping jaws (gripping jaws with a large radial protrusion length).

[0008] Furthermore, in a conventional swing-in type chuck device, the gripping jaws employ a swinging mechanism by a restrictor spring. For this reason, there is a large resistance to the swinging of the gripping jaws, and there is a risk of causing distortion especially to thin-walled workpieces.

[0009] Therefore, the problems of this invention are, as a first problem, to simplify the operation when switching the gripping force of the workpiece, as a second problem, to prevent the grip of the workpiece by the gripping jaws from loosening due to centrifugal force, and as a third problem, to prevent the swinging function of the gripping jaws from causing distortion to the workpiece.

Means for Solving the Problem

[0010] In order to solve the above problems, the present invention includes a drawbar that moves forward and backward along the axial direction of the central axis of the chuck body, a toggle actuator swingably supported by the chuck body, a gripping portion provided at the front end of the toggle actuator, an engaging convex portion provided at the rear end of the toggle actuator, and an engaging concave portion provided on the outer periphery of the drawbar with which the engaging convex portion engages. The engaging convex portion is movable in the radial direction with respect to the engaging concave portion, and by axially pressing the engaging convex portion by the forward and backward movement of the drawbar in the axial direction, the toggle actuator is swung in the radial direction to grip the workpiece with the gripping portion. The toggle actuator is provided with a weight at its rear end, and the weight is axially biased forward by a biasing means with respect to the chuck body, and a chuck device is adopted.

[0011] Here, the gripping portion is swingable around a swing center line parallel to the axial direction with respect to the toggle actuator. Either the gripping portion or the toggle actuator is provided with a mortar-shaped concave portion whose inner diameter decreases toward the bottom, and the other is provided with a plunger that enters the concave portion. The plunger is axially pressed toward the concave portion by an elastic member.

[0012] At this time, among the weights of the toggle actuator, the gripping portion, the weight, and the members for fixing the gripping portion and the weight to the toggle actuator, the product of the forward-side weight corresponding to the forward-side portion located on the front side of the swing center of the toggle actuator and the distance from the swing center to the center-of-gravity position of the forward-side portion, and the product of the rear-side weight corresponding to the rear-side portion located on the rear side of the swing center and the distance from the swing center to the center-of-gravity position of the rear-side portion are preferably set to be equal.

Advantages of the Invention

[0013] This invention can exhibit at least one of the following effects. That is, it is possible to simplify the operation when switching the gripping force of the workpiece, or it is possible to prevent the workpiece from being loosened by the gripping claws due to centrifugal force, or it is possible to prevent the workpiece from being distorted by the swinging function of the gripping claws.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9A

Figure 9B

Mode for Carrying Out the Invention

[0015] An embodiment of this invention will be described with reference to the drawings. The swing-in type chuck device of this embodiment (hereinafter simply referred to as chuck device A) is provided with a drawbar 8 on the central axis 6 of the chuck body 1 as shown in FIG. 1, and the drawbar 8 is movable forward and backward along the central axis 6 of the chuck body 1. The drawbar 8 is concentrically provided with a support drawbar 9 via a fixing bolt 8a near the front thereof. Hereinafter, the drawbar 8 and the support drawbar 9 and the like that move forward and backward in the axial direction integrally with the drawbar 8 are simply referred to as the drawbar 8. Further, the direction of the central axis 6 of the chuck body 1 is referred to as the axial direction, the center line of the central axis 6 is referred to as the axis center, and the direction orthogonal to the axis center is referred to as the radial direction.

[0016] The dropper 8 is connected to the lifting actuator 10. The lifting actuator 10 is provided with a gripping portion 15 that abuts against the workpiece W at its tip. In this embodiment, as shown in FIG. 2, three gripping portions 15 are provided at equal angular intervals around the axis of the chuck body 1. Since one gripping portion 15 is provided for each lifting actuator 10, the same number (three) of lifting actuators 10 are also provided at equal angular intervals around the axis of the chuck body 1. However, the number and orientation of the gripping portions 15 and the lifting actuators 10 are appropriately set according to the workpiece to be gripped and the specifications of the chuck device A. A carbide insert is attached to the tip 15a of the gripping portion 15 as needed to improve the gripping torque on the workpiece W and the durability of the gripping claws that contact the workpiece W.

[0017] The lifting actuator 10 is supported so as to be swingable in the radial direction with respect to the chuck body 1. As shown in FIG. 1, the supporting method is such that a spherical portion 12 formed in the middle in the longitudinal direction of the lifting actuator 10, which is a longitudinal member, meshes with the spherical inner periphery 16a of a supporting member (bearing race) 16 attached to the chuck body 10, and the two are slidable. Thereby, the front end of the lifting actuator 10 is swingable in the radial direction with respect to the chuck body 1. Further, an engaging convex portion 13 extending toward the inner diameter side is provided at the rear end 11 of the lifting actuator 10. The supporting member 16 is inserted into a hole 18 machined at an equal angular position around the axis from the end face side of the housing 2 and is fixed to the housing 2 with bolts. A stopper 3 is fixed to the front surface of the chuck body 1 via a spacer 4. The stopper 3 positions the workpiece W in the axial direction by abutting against the workpiece W. In the embodiment, three holes 18 are set, but the number of holes 18 can be arbitrarily set according to the number of lifting actuators 10 to be set.

[0018] The housing 2 is composed of a front housing 2a located on the front side of the chuck body 1 and a rear housing 2b located on the rear side, and a space 7 is formed inside thereof. The rear end 11 of the bellows actuator 10 is housed in this space 7. The engaging convex portion 13 of the bellows actuator 10 has end faces 13a and 13b on both axial sides, and the space between the end faces 13a and 13b protrudes toward the inner diameter side. An engaging concave portion 5 is formed on the outer periphery of the support drawbar 9, and the engaging convex portion 13 of the bellows actuator 10 is housed in the engaging concave portion 5. The engaging concave portion 5 is provided with end faces 5a and 5b that rise upward in the outer diameter direction from both axial sides of the bottom surface thereof. The end faces 13a and 13b on the outer surface of the engaging convex portion 13 are in sliding contact with the end faces 5a and 5b on the inner surface of the engaging concave portion 5, respectively. Also, a gap a is interposed between the inner surface 13c of the engaging convex portion 13 and the bottom surface 5c of the engaging concave portion 5 (see FIG. 1). Thereby, the engaging convex portion 13 is movable in the radial direction with respect to the support drawbar 9 and immovable in the axial direction.

[0019] By moving forward and backward in the axial direction together with the drawbar 8, the engaging convex portion 13 of the bellows actuator 10 is axially pressed. By this pressing, the outer surface 12a of the spherical portion 12 of the bellows actuator 10 and the spherical inner surface 16a of the support member 16 slide, and the bellows actuator 10 swings around the center of the spherical portion 12 (swing center P). Thereby, the gripping portion 15 at the front end moves in the radial direction. By the radial movement of the gripping portion 15, the gripping portion 15 can grip the outer periphery of the workpiece W and also release the gripping. That is, as an operating mechanism of the drawbar 8 and the bellows actuator 10, a cam lever structure without a locking action is adopted.

[0020] Here, the locking action will be described. In a conventional chuck device, the jaw actuator has a shaft portion that extends rearward, and the shaft portion is supported by an actuator that is operated by a drawbar or the like. For this reason, the axial direction of the shaft portion of the jaw actuator is inclined with respect to the axial center direction of the chuck body (see Patent Documents 1 and 2). When the actuator is pulled rearward along the axial center direction of the chuck body, due to the wedge effect between them, the drawbar, the actuator, and the jaw actuator mesh with each other and enter a locked state. Such a locking action is likely to cause problems when switching the gripping force of the workpiece from high pressure to low pressure. To release this locking action, it is necessary to once release the gripping of the workpiece and then grip it again with the desired gripping force.

[0021] On the other hand, in the chuck device of the present invention, there is no inclined shaft portion that causes a wedge effect, and no locking action occurs. For this reason, it is not necessary to grip the workpiece again when switching the gripping force from high pressure to low pressure.

[0022] Specifically explaining the operation, when the workpiece W is gripped, the drawbar 8 retreats to the left side (arrow B) shown in FIG. 3, and the engaging convex portion 13 of the jaw actuator 10 is also pressed in the retreat direction. At this time, while the end faces 5a and 5b of the engaging concave portion 5 and the end faces 13a and 13b of the engaging convex portion 13 are in sliding contact, the jaw actuator 10 swings around the swing center P (arrow C), and the gripping portion 15 at the front end moves radially inward (arrow D). Thereby, the gripping portion 15 grips the outer periphery of the workpiece W. At this time, the workpiece W is drawn slightly rearward by the gripping portion 15 and gripped, and the workpiece W abuts against the stopper 3 on the front surface and is positioned in the axial direction.

[0023] Here, when the compensator actuator 10 swings, the engaging convex portion 13 slightly moves radially within the engaging concave portion 5 of the support drover 9, and the gap a expands and contracts. Since the engaging convex portion 13 can move radially, the workpiece W is gripped with a gentle force according to the shape of the outer periphery of the workpiece W, and a so-called center compensation function is exhibited. The center compensation function is a function in which, in a state where the axis of the chuck body 1 coincides with the reference point of the workpiece W, the workpiece W is gripped with an equal force around it. Here, the engaging convex portion 13 of the compensator actuator 10 protrudes toward the inner diameter side, and the engaging concave portion 5 in which the engaging convex portion 13 is housed opens toward the outer diameter side. By adopting such an engaging structure, no wedge effect occurs as in the conventional chuck device, and no locking action occurs.

[0024] In particular, the protruding direction of the engaging convex portion 13 of the compensator actuator 10 is orthogonal to the axial direction of the support drover 9 integrated with the drover 8. Further, as shown in FIG. 8, the compensator actuator 10 and the gripping portion 15 are in a state where the direction line X toward the tip 15a of the gripping portion 15 and the direction line Y toward the center 5a of the engaging concave portion 5 of the support drover 9 (the intersection of the axial center line F, which is the center line in the axial direction of the engaging concave portion 5, and the bottom surface of the engaging concave portion 5) are bent (the crossing angle α > 90° toward the inner diameter side), and it has a cam lever structure utilizing the principle of a lever. By adopting such a structure, the locking action due to the above-described wedge effect can be more reliably avoided.

[0025] On the other hand, when the gripping of the workpiece W is released, the drover 8 advances to the right side (the opposite direction of the arrow B) shown in FIG. 3, and the engaging convex portion 13 of the compensator actuator 10 is also pressed in the advancing direction. The compensator actuator 10 swings around the swing center P (in the opposite direction of the arrow C), and the gripping portion 15 at the front end moves radially outward (in the opposite direction of the arrow D). Thereby, the gripping of the workpiece W by the gripping portion 15 is released.

[0026] Further, the Z-axis actuator 10 is provided with a weight 20 at its rear end 11. As shown in FIG. 4, the weight 20 is biased axially forward with respect to the housing 2 of the chuck body 1 by a biasing means 30.

[0027] The weight 20 is provided with a concave portion 23 into which a convex portion 14 provided at the rear end 11 of the Z-axis actuator 10 fits. The convex portion 14 has a rectangular cross-section that protrudes rearward at the rear end 11 of the Z-axis actuator 10, and its end face 14a, inner diameter surface 14b, and outer diameter surface 14c are each flat surfaces. Further, the concave portion 23 has a shape in which a recess with a rectangular cross-section is recessed rearward, and its bottom surface 23a, inner diameter surface 23b, and outer diameter surface 23c are each flat surfaces. In a state where the convex portion 14 is fitted into the concave portion 23, the end face 14a, inner diameter surface 14b, and outer diameter surface 14c are in surface contact with the bottom surface 23a, inner diameter surface 23b, and outer diameter surface 23c, respectively. Furthermore, the weight 20 and the Z-axis actuator 10 are integrated by a bolt 26 screwed in from the rear to the front. At this time, the end face 11a of the stepped portion 10a provided on the outer diameter side of the convex portion 14 of the Z-axis actuator 10 and the end face 21b of the protruding portion 24 provided on the outer diameter side of the concave portion 23 of the weight 20 face each other with a gap therebetween. Also, the end face 11b of the stepped portion 10b provided on the inner diameter side of the convex portion 14 of the Z-axis actuator 10 and the end face 21c of the protruding portion 25 provided on the inner diameter side of the concave portion 23 of the weight 20 face each other with a gap therebetween.

[0028] The biasing means 30 includes an elastic member 31 housed in a hole 22 provided to open on the rear end face 21a of the weight 20, and a cap member 32 connected to the elastic member 31. In this embodiment, a coil spring is employed as the elastic member 31, but a spring or elastic body having other forms may also be used. The cap member 32 has a cap shape in which the rear end of the cylindrical portion 32a is closed by the head portion 32b and the front end is open. The front end of the elastic member 31 abuts against the bottom 22a of the hole 22, and the rear end of the elastic member 31 enters the inside from the opening at the front end of the cap member 32 and abuts against the bottom on the head portion 32b side. The head portion 32b of the cap member 32 protrudes rearward from the rear end face 21a of the weight 20 at the front end, and the head portion 32b abuts against the inner end face 7a of the housing 2. At this time, the elastic member 31 is in a state slightly compressed from its natural length. For this reason, the weight 20 is biased axially forward with respect to the chuck body 1 by the biasing means 30. Note that it is preferable that the head portion 32b of the cap member 32 has a spherical shape so that it can make point contact with the inner end face 7a of the housing 2.

[0029] According to the present invention, since the joggle actuator 10 is operated using a cam lever structure without a locking action, it is not necessary to re-grasp when changing the strength of the force for gripping the work W. That is, when switching the gripping force of the work W from high pressure to low pressure, it is possible to shift to the desired gripping force as it is without once releasing the gripping of the work W. Further, since the joggle actuator 10 is biased axially forward through the weight 20, the increase and decrease of the gripping force of the work W are also smooth in this respect.

[0030] Further, according to the present invention, since the weight 20 is provided on the rear end side of the joggle actuator 10, the gripping of the work W by the gripping portion 15 does not loosen due to the centrifugal force associated with the high-speed rotation of the chuck. Providing the weight 20 on the rear end 11 side, which is on the opposite side of the front-end gripping portion 15 with respect to the swing center P of the joggle actuator 10, is effective in preventing the opening (loosening) of the gripping portion 15 due to the centrifugal force. Further, by reducing the increase and decrease of the gripping force due to the change in the rotational speed, it is possible to suppress the work distortion generated with the change in the rotational speed.

[0031] Here, among the weight of the lifting actuator 10, the gripping part 15, the weight 20, and the members for fixing the gripping part 15 and the weight 20 to the lifting actuator 10, the product of the front-side weight corresponding to the front-side part located on the front side of the swing center P of the lifting actuator 10 and the distance L1 from the swing center P to the center-of-gravity position G1 of the front-side part is preferably set to be equal to the product of the rear-side weight corresponding to the rear-side part located on the rear side of the swing center P and the distance L2 from the swing center P to the center-of-gravity position G2 of the rear-side part.

[0032] That is, as shown in FIG. 8, in any cross-section passing through the axis, the weight of the portion on the front side of the swing center P (referred to as the front-side portion), that is, the weight of the jo actuator 10, and the base portion 15c of the gripping portion 15 and the claw member 15b to be described later, the mounting portion 17 for fixing the gripping portion 15 to the jo actuator 10, the plunger 42, the weight 20, and the total weight of the members of the portion located on the front side of the swing center P among the weights of bolts for fixing the weight 20 to the jo actuator 10 (referred to as the front-side weight), and the distance L1 from the swing center P to the center-of-gravity position G1 of the front-side portion, and the weight of the portion on the rear side of the swing center P (referred to as the rear-side portion), that is, the weight of the jo actuator 10, and the base portion 15c of the gripping portion 15 and the claw member 15b to be described later, the mounting portion 17 for fixing the gripping portion 15 to the jo actuator 10, the plunger 42, the weight 20, and the total weight of the members of the portion located on the rear side of the swing center P among the weights of bolts for fixing the weight 20 to the jo actuator 10 (referred to as the rear-side weight), and the distance L2 from the swing center P to the center-of-gravity position G2 of the rear-side portion are preferably equal in arrangement or weight. That is, when the chuck body 1 rotates, if the front-side weight corresponding to the front-side portion and the rear-side weight corresponding to the rear-side portion are balanced by their centrifugal forces with the swing center P as the fulcrum, the centrifugal force acting on the gripping portion 15 is canceled out, so a stable and desirable gripping state can be obtained. To achieve this state, it is effective to provide the weight 20 on the rear end 11 side of the jo actuator 10. By setting as described above, the effect of canceling out the centrifugal force acting on the gripping portion 15 (the force that the gripping portion 15 tries to open to the outer diameter side) by the centrifugal force acting on the weight 20 can be enhanced more.

[0033] In FIG. 8, the line connecting the swing center P and the center of gravity G1 and the line connecting the swing center P and the center of gravity G2 are on the same straight line, and their directions are parallel to the axial direction. Considering the balance of the centrifugal forces on the front side and the rear side, such a mode is desirable. However, a mode in which either or both of the line connecting the swing center P and the center of gravity G1 and the line connecting the swing center P and the center of gravity G2 have an angle with respect to the axial direction may also be adopted.

[0034] Further, according to the present invention, by providing the biasing means 30 for biasing the jaw actuator 10 forward, it is possible to switch the presence or absence of the chucking function by replacing the bearing race as the support member 16. FIG. 7 shows an unclamped state in which the workpiece W is released. FIG. 8 shows a clamped state in which the workpiece W is gripped. In FIGS. 7 and 8, as the support member 16, the one shown in FIG. 9A corresponding to the retracting function is used. The support member 16 shown in FIG. 9A has its inner surface composed of a spherical surface portion 16a and a cylindrical surface portion 16b. The spherical surface portion 16a is provided so as to be divided into a front side and a rear side with the central cylindrical surface portion 16b interposed therebetween. The cylindrical surface portion 16b has a minute length v in the front-rear direction of the chuck body 1.

[0035] In the unclamped state, as shown in FIG. 7, the jaw actuator 10 is moved forward by the biasing force of the biasing means 30. For this reason, a gap w1 is interposed between the spherical portion 12 of the jaw actuator 10 and the support member 16 on the rear side. When the clamped state is reached, as shown in FIG. 8, the jaw actuator 10 is moved rearward against the biasing force of the biasing means 30. For this reason, a gap w2 is interposed between the spherical portion 12 of the jaw actuator 10 and the support member 16 on the front side. By this rearward movement, the workpiece W is gripped in a state of being retracted to the stopper 3 side on the front surface of the chuck body 1. When the retracting function is not required, the support member 16 shown in FIG. 9B can be used. The support member 16 shown in FIG. 9B does not include the cylindrical surface portion 16b and has an inner surface composed only of the spherical surface portion 16a.

[0036] Also, in this embodiment, the gripping portions 15 are each provided with a neck swing mechanism 40. The neck swing mechanism 40 can be selectively employed according to the type of the workpiece W and the specifications of the inspection device A.

[0037] As shown in FIGS. 1 and 5, the gripping portion 15 is detachably attached to a mounting portion 17 provided at the front end of the jo actuator 10. As shown in FIGS. 5 and 6, the mounting portion 17 includes a protruding portion 56 that protrudes to both side sides (circumferential direction of the chuck body 1) and a groove portion 57 located rearward of the protruding portion 56. As shown in FIG. 1, the gripping portion 15 includes a base 15c fixed to the mounting portion 17 and a claw member 15b fixed to the base portion 15c. The inner diameter side end of the claw member 15b is a tip 15a that grips the workpiece W. The base portion 15c is fixed to the mounting portion 17 via a support member 51 that forms a part of the neck swing mechanism 40.

[0038] As shown in FIG. 6, the support member 51 has a concave cross-sectional shape surrounding the mounting portion 17. The support member 51 includes a groove portion 55 into which the protruding portion 56 of the mounting portion 17 enters and a protruding portion 54 that enters the groove portion 57 of the mounting portion 17, respectively, on both sides. In a state where the protruding portion 56 of the mounting portion 17 is fitted into the groove portion 55 of the support member 51 and the protruding portion 54 of the support member 51 is fitted into the groove portion 57 of the mounting portion, the support member 51 and the jo actuator 10 (mounting portion 17) are integrated by a bolt 17a screwed from the front to the rear.

[0039] Clearances w1, w2, w3, and w4 are set between the front end surface of the protruding portion 56 of the mounting portion 17 and the bottom surface of the groove portion 55 of the support member 51, and between the bottom surface of the groove portion 57 of the mounting portion 17 and the front end surface of the protruding portion 54 of the support member 51, respectively. For this reason, the support member 51 is swingable about the neck in a direction to expand and contract the clearances w1, w2, w3, and w4 with respect to the mounting portion 17. The neck swing direction corresponds to the arrow X and Y directions shown in FIG. 2. Note that if locking means 53 including a bolt 53a and a nut 53b is used, the support member 51 can be locked at an arbitrary swing position with respect to the mounting portion 17, and the neck swing function can be stopped.

[0040] Here, the oscillating mechanism 40 is provided with a cone-shaped recess 44, the inner diameter of which decreases toward the bottom, on one of the gripping portion 15 and the jaw actuator 10, and a plunger 42 that fits into the recess 44 on the other. The plunger 42 is pressed axially toward the recess 44 by an elastic member 41. In this embodiment, as shown in Fig. 6, the recess 44 is provided on the mounting portion 17 side and the plunger 42 is provided on the support member 51 side, but this may be reversed and the plunger 42 may be provided on the mounting portion 17 side and the recess 44 on the support member 51 side.

[0041] The plunger 42 includes an elastic member 41 housed in a hole provided at the rear end surface of the support member 51 and a cap member 42 connected to the elastic member 41. In this embodiment, a coil spring is used as the elastic member 41, but other types of springs and elastic bodies may be used. The cap member 42 has a cap shape in which the rear end of the cylindrical portion 42a is closed by the head portion 42b and the front end is open. The front end of the elastic member 41 abuts against a blocking plate 52 fixed to the support member 51 so as to block the bottom of the hole. The rear end of the elastic member 41 enters the inside of the cap member 42 from the opening at the front end and abuts against the bottom on the head portion 42b side. The head portion 42b of the cap member 42 enters the mortar-shaped recess 44. At this time, the elastic member 41 is in a state slightly compressed from its natural length.

[0042] 2, the head 42b of the plunger 42 tries to move in a direction to leave the recess 44. However, since the plunger 42 is biased rearward along the axial direction of the chuck body 1, the head 42b of the plunger 42 biases the support member 51 in a direction to return to the deepest part (referred to as the neutral position) of the recess 44. This biasing direction is opposite to the arrow X or the arrow Y direction shown in FIG. 2, so that the gripping portion 15 can grip the workpiece W with a gentle elastic force in a direction to return to the neutral position in response to the movement of the gripping portion 15 to swing in accordance with the shape of the workpiece W.

[0043] In the conventional rocking and retracting chuck device, a restrictor spring (for example, a coil spring or the like having a coil axis arranged along the rocking direction of the gripping claw) was adopted as the rocking mechanism set for the gripping claw. Therefore, there was a large resistance to the rocking of the gripping claw, and there was a risk of causing distortion, particularly for thin workpieces. However, according to this invention, when the gripping portion 15 rocks, an elastic member and a plunger that act with an elastic force in the axial direction of the chuck body 1 are adopted. Thus, the workpiece W is gripped with a gentle elastic force without causing distortion to the workpiece W.

[0044] The embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The scope of this invention is shown not by the above description but by the claims, and it is intended that the meaning equivalent to the claims and all modifications within the scope thereof are included.

Explanation of Reference Numerals

[0045] 1 Chuck body 2 Housing 5 Engaging recess 6 Central axis 8 Draw bar 10 Hoisting actuator 11 Rear end 12 Spherical portion 13 Engaging convex portion 15 Gripping portion 41 Elastic member 42 Plunger 44 Receiving recess A Chuck device F Axial center line G Center of gravity P Rocking center W Workpiece

Claims

1. A draw bar (8) that moves forward and backward along the axial direction of the central axis (6) of the chuck body (1), A toggle actuator (10) swingably supported by the chuck body (1), A gripping portion (15) provided at the front end of the toggle actuator (10), An engaging convex portion (13) provided at the rear end (11) of the toggle actuator (10), An engaging concave portion (5) provided on the outer periphery of the draw bar (8) with which the engaging convex portion (13) engages, and comprising, The engaging convex portion (13) is movable in the radial direction with respect to the engaging concave portion (5), By advancing and retreating the draw bar (8) in the axial direction to axially press the engaging convex portion (13), the toggle actuator (10) is swung in the radial direction to grip the workpiece (W) with the gripping portion (15), and also release the gripping, The toggle actuator (10) has a weight (20) at its rear end (11), and the weight (20) is axially biased forward by a biasing means (30) with respect to the chuck body (1). A chuck device.

2. The gripping portion (15) extends along the circumferential direction around the axis of the central axis (6), and the gripping portion (15) is such that one end in the circumferential direction around the axis of the central axis (6) with respect to the toggle actuator (10) is in a direction away from the central axis (6) and at the same time the other end in the circumferential direction is swingable so as to swing in a direction approaching the central axis (6), Either the gripping portion (15) or the toggle actuator (10) is provided with a mortar-shaped concave portion (44) whose inner diameter becomes smaller as it goes towards the bottom along the axial direction of the central axis (6) and reaches the deepest part, and the other is provided with a plunger (42) having a head (42b) that enters the concave portion (44). The chuck device according to claim 1, wherein the head (42b) of the plunger (42) is axially pressed towards the bottom of the concave portion (44) by an elastic member (41), so that the plunger (42) biases the gripping portion (15) in a direction to return to a neutral position where the head (42b) enters the deepest part of the bottom of the concave portion (44).

3. Among the weights of the jo actuator (10), the gripping part (15), the weight (20), and the members for fixing the gripping part (15) and the weight (20) to the jo actuator (10), the front-side weight corresponding to the front-side part located on the front side of the swing center (P) of the jo actuator (10), the product of the distance (L1) from the swing center (P) to the center-of-gravity position (G1) of the front-side part, the rear-side weight corresponding to the rear-side part located on the rear side of the swing center (P), and the product of the distance (L2) from the swing center (P) to the center-of-gravity position (G2) of the rear-side part are set to be equal. The chuck device according to claim 1 or 2.

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