JP2023122372A - Clamp device - Google Patents

Abstract

To provide a clamp device that enables positions of a work-piece and a clamp arm to be easily adjusted and can enlarge a range where clamp force can be secured.SOLUTION: A pair of link plates 13 are provided with cam grooves 23 penetrating in a thickness direction through the link plates 13. When the cam grooves 23 are viewed from outer surface sides along the thickness direction of the link plates 13, first ends in a circular arc-shape of the cam grooves 23 are at a position close to a link plate fulcrum shaft 17, and the cam grooves 23 extend so as to separate from the link plate fulcrum shaft 17 as approaching second ends in a circular arc-shape of the cam grooves 23.SELECTED DRAWING: Figure 4

Description

The present invention relates to clamping devices.

2. Description of the Related Art Conventionally, there has been known a clamping device for clamping a work such as a panel material when welding the work. The clamping device described in Patent Document 1 includes a main body, a clamp arm supported by an end of the main body, a first link member supported by the clamp arm, and a second link member supported by the main body and the first link member. and a link member.

One end of the first link member is axially fixed to the clamp arm by a pin, and the other end of the first link member is axially fixed to the rod of the cylinder which is axially fixed to the main body. One end of the second link member is pivoted to the central portion of the first link member via a pin, and the other end of the second link member is pivoted to the main body via a pin. A cylinder as a drive source swings the first link member to swing the clamp arm via the second link member. A first axis is defined as a line between the axes of a pin for fixing one end of the first link member and a pin for fixing one end of the second link member. A second axis is defined as a line between the axes of a pin that supports the other end of the first link member and a pin that supports the other end of the second link member. The angle formed by the first axis and the second axis is defined as the angle θ1 formed by the link mechanism. The contact position between the workpiece and the tip of the clamp arm is provided just before the dead point where the angle θ1 formed by the link mechanism is 180°.

Japanese Utility Model Publication No. 60-4663

However, as shown by the dashed line in FIG. 10, in the toggle-type clamping device described in Patent Document 1, when the fulcrum, force point, and action point of the link mechanism are aligned on the same straight line, the clamping force is greatly reduced. . Therefore, for example, it is required to adjust the positional relationship between the workpiece and the clamp arm so that the angle .theta.1 formed by the link mechanism is smaller than 180.degree. in order to secure the clamping force.

At this time, the tip of the clamp arm is worn due to contact with the workpiece. For this reason, when adjusting the positional relationship between the workpiece and the clamp arm, it is necessary to allow for a wear margin at the tip of the clamp arm. However, since a large wear margin cannot be secured, it is troublesome to adjust the positional relationship between the workpiece and the clamp arm, including checking the amount of wear at the tip of the clamp arm.

A clamping device for solving the above problems comprises a main body, an arm swingably supported by the main body by an arm rotation shaft, a link plate swingably supported by the main body by a link plate fulcrum shaft, and the link a link member having a first end swingably supported to a plate by a link plate action shaft and a second end swingably supported to the arm by a link rotation shaft; an actuator; and an auxiliary plate fixed to the main body, the auxiliary plate having a guide groove for guiding the guide shaft through which the guide shaft is inserted. The link plate is provided with a cam groove through which the guide shaft is inserted, and the cam groove is such that the distance between the link plate fulcrum shaft and the guide shaft at the time of clamping is the same as the link at the time of unclamping. The guide shaft is formed to be longer than the distance between the plate fulcrum shaft and the guide shaft, and the engagement position of the guide shaft with respect to the cam groove is determined by the engagement between the guide groove and the guide shaft.

In the above clamping device, the guide groove preferably has a first groove extending along an arcuate trajectory centered on the link plate fulcrum axis, and a second groove extending continuously from the first groove.

In the above clamping device, the second groove preferably extends away from the arc extending along the first groove as it extends away from the first groove.
In the above clamp device, the cam groove is arc-shaped, and the radius of curvature of the cam groove is farther from the link plate fulcrum axis in the cam groove than the portion of the cam groove located closer to the link plate fulcrum axis. It is preferable that the part located on the

In the clamp device described above, the second groove may be provided linearly.
In the above clamping device, it is preferable that the guide shaft is clamped in the second groove of the guide groove.

According to the present invention, it is possible to widen the range in which the clamping force can be secured while facilitating position adjustment between the workpiece and the clamp arm.

The disassembled perspective view which shows the clamp apparatus in embodiment. The disassembled rear view which shows a clamp apparatus. The side view which shows the clamp device at the time of unclamping in embodiment. FIG. 4 is a partial side view showing an enlarged clamping device during unclamping; FIG. 4 is a partial rear view showing an enlarged clamping device; The side view which shows the clamping device at the time of clamping in an initial setting. FIG. 4 is a partial side view showing an enlarged clamping device at the time of clamping in the initial setting; FIG. 4 is a side view showing the clamping device during clamping at the wear limit; FIG. 4 is a partial side view showing an enlarged clamping device during clamping at the wear limit; 4 is a graph showing the relationship between the angle θ1 formed by the link mechanism and the clamping force; 4 is a graph showing the relationship between the angle θ2 formed by the arm and the clamping force;

An embodiment embodying a clamping device will be described below with reference to FIGS. 1 to 11. FIG.
As shown in FIG. 1, FIG. 2, FIG. 3, or FIG. , and a cylinder 30 as an actuator. Arm 12 is connected to main body 11 by arm rotation shaft 16 .

An arm rotating shaft 16 is inserted through the base end side of the arm 12 indicated by the dashed line in FIG. That is, the main body 11 and the arm 12 are connected by inserting the arm rotating shaft 16 . The arm rotating shaft 16 is fixed to the main body 11 . Therefore, the arm 12 can swing with respect to the main body 11 about the central axis of the arm rotating shaft 16 . The arm 12 has a contactor A1 detachably fixed to the tip of the arm 12. As shown in FIG. The arm 12 clamps the work W when the contact surface 120 of the contactor A1 comes into contact with the contact surface W1 of the work W. As shown in FIG. The contactor A1 has a wear margin M1 in consideration of wear due to the clamping of the workpiece W by the arm 12 . The contactor A1 has a portion that protrudes from the arm 12 by having a wear margin M1. The clamping direction Z is the direction in which the arm 12 faces the workpiece W with the arm rotating shaft 16 as the swing center.

A pair of auxiliary plates 15 are fixed to the main body 11 . A pair of auxiliary plates 15 are fixed to the main body 11 so as to sandwich the main body 11 in the thickness direction. Each of the pair of auxiliary plates 15 is provided with a guide groove 20 penetrating through the auxiliary plate 15 in the thickness direction. The pair of guide grooves 20 face each other in the thickness direction of the main body 11 . Each of the pair of guide grooves 20 has a first groove 21 and a second groove 22 . The second groove 22 extends continuously from the first groove 21 .

As shown in FIG. 4, viewing the guide groove 20 from the thickness direction and the outer surface side of the auxiliary plate 15 is referred to as a side view. Here, a virtual line C is defined as an arc centered on the link plate fulcrum shaft 17 and extending along the first groove 21 . When the auxiliary plate 15 is viewed from the side, the second groove 22 extends away from the imaginary line C as it extends away from the first groove 21 . Therefore, the second groove 22 extends away from the link plate fulcrum axis 17 .

A pair of link plates 13 are supported by the body 11 . The pair of link plates 13 are arranged between the pair of auxiliary plates 15 so as to sandwich the main body 11 in the thickness direction. Therefore, one link plate 13 is arranged between the main body 11 and one auxiliary plate 15 , and the other link plate 13 is arranged between the main body 11 and the other auxiliary plate 15 .

A link plate fulcrum shaft 17 is inserted through the pair of link plates 13 . The link plate fulcrum shaft 17 penetrates the main body 11 and is swingably supported. Therefore, the link plate 13 can swing with respect to the main body 11 with the link plate fulcrum shaft 17 as the swing center.

The pair of link plates 13 are provided with cam grooves 23 penetrating through the link plates 13 in the thickness direction. The cam groove 23 is arcuate. Viewing the cam grooves 23 from the outer surface side along the thickness direction of the link plate 13 is referred to as a side view of the link plate 13 . When the link plate 13 is viewed from the side, the first end of the arc of the cam groove 23 is located near the link plate fulcrum shaft 17 . Also, when the link plate 13 is viewed from the side, the cam groove 23 extends away from the arm 12 . Also, the first groove 21 extends along an arc centered on the link plate fulcrum axis 17 .

A link rotating shaft 12a that is swingably supported by the arm 12 is inserted through the first ends 14a of the pair of link members 14 . The pair of first ends 14a can swing relative to the arm 12 about the center axis of the link rotating shaft 12a. Therefore, the first end 14a is swingably supported. A link plate action shaft 19 is inserted through the second ends 14 b of the pair of link members 14 . The pair of link members 14 are swingably supported by the link plate action shaft 19 with respect to the pair of link plates 13 while sandwiching the arm 12 in the thickness direction. The pair of link plates 13 are restrained from being displaced from each other by the link plate fulcrum shaft 17 and the link plate action shaft 19, and are held in a state in which the pair of cam grooves 23 face each other.

The cylinder 30 is provided with a piston rod 31 capable of reciprocating motion by inflow and outflow of compressed air to and from the cylinder 30 .
As shown in FIG. 1, FIG. 2, FIG. 3, FIG. 4, or FIG. 5, a pair of cylinder rotating shafts 30a are fixed to the tip of the rod-side cover of the cylinder 30 from which the piston rod 31 protrudes. A pair of cylinder rotation shafts 30a are provided in the cylinder 30 so that their axes are aligned. Each cylinder rotating shaft 30a passes through the auxiliary plate 15 in the thickness direction. Each cylinder rotating shaft 30 a is slidable with respect to the auxiliary plate 15 . A bolt 18 is screwed from the outside of the auxiliary plate 15 to the cylinder rotating shaft 30a passing through the auxiliary plate 15 . The auxiliary plate 15 is positioned in the thickness direction by bolts 18 . Therefore, the cylinder 30 can swing with respect to the main body 11 and the auxiliary plate 15 about the central axis of the cylinder rotating shaft 30a.

A clevis 32 is connected to the tip of the piston rod 31 . A guide shaft 33 is fixed to the tip of the clevis 32 . A first direction Y is the axial direction of the guide shaft 33 . Both ends of the guide shaft 33 in the axial direction protrude from the clevis 32 .

A first cam follower 34 is provided at each of both ends of the guide shaft 33 in the axial direction. A second cam follower 35 is provided outside the first cam follower 34 at each of both ends of the guide shaft 33 in the axial direction. Each of the pair of first cam followers 34 is rotatably supported on the guide shaft 33 . Each of the pair of second cam followers 35 is rotatably supported on the guide shaft 33 .

A portion of the guide shaft 33 is inserted through the cam groove 23 of the link plate 13 via the first cam follower 34 . Each of the outer peripheral surfaces of the pair of first cam followers 34 is in contact with the cam groove 23 of the link plate 13 . Also, the guide shaft 33 is inserted through the guide groove 20 of the auxiliary plate 15 via the second cam follower 35 . Each of the outer peripheral surfaces of the pair of second cam followers 35 is in contact with the guide groove 20 of the auxiliary plate 15 . The cylinder 30 is swingably supported by a cylinder rotating shaft 30a. The second cam follower 35 engages with the guide groove 20 of the auxiliary plate 15 . Therefore, the movement of the piston rod 31 in the projecting direction allows the second cam follower 35 to move along the track from the first groove 21 to the second groove 22 .

The first cam follower 34 is arranged coaxially with the second cam follower 35 . The first cam follower 34 is engaged with the cam groove 23 of the link plate 13 . The engagement position of the first cam follower 34 with the cam groove 23 of the link plate 13 is determined by the guide groove 20 of the auxiliary plate 15 . Therefore, when the clevis 32 is linearly moved with respect to the cylinder 30 by the cylinder 30, the guide shaft 33 and the second cam follower 35 are also linearly moved with respect to the cylinder 30, and the second cam follower 35 moves along the guide groove. 20. Similarly, when the clevis 32 is linearly moved with respect to the cylinder 30 by the cylinder 30, the guide shaft 33 and the first cam follower 34 are also linearly moved with respect to the cylinder 30, and the first cam follower 34 moves along the cam groove. 23. Therefore, the arm 12 , link plate 13 and auxiliary plate 15 are linked by the guide shaft 33 , first cam follower 34 and second cam follower 35 .

A pair of link members 14 are arranged on the outer sides of the arms 12 in the first direction Y, respectively. A pair of link plates 13 are arranged outside the pair of link members 14 in the first direction Y, respectively. A pair of auxiliary plates 15 are arranged outside the pair of link plates 13 in the first direction Y, respectively. The arm 12 is provided with a second fastener 12b.

Next, the action of the clamping device 10 will be described together with the clamping operation.
Here, in a side view of the clamp device 10, a straight line H1 passing through the center of the link plate action shaft 19 and the center of the link rotation shaft 12a, and a straight line passing through the center of the link rotation shaft 12a and the center of the link plate fulcrum shaft 17 The angle formed by H2 is defined as a link angle θ1. The angle between a straight line H3 passing through the center of the guide shaft 33 and the center of the link plate fulcrum shaft 17 and a straight line H4 passing through the center of the guide shaft 33 and the center of 18a is defined as a link angle θ3.

Here, the radius of curvature of the arc of the cam groove 23 will be explained using the link angle θ3. The radius of curvature of the arc of the cam groove 23 is smaller in the portion away from the link plate fulcrum shaft 17 than in the portion located closer to the link plate fulcrum shaft 17 . That is, the moment (F×L×sin θ3) generated on the guide shaft 33 is gradually reduced. In addition, the thrust force of the cylinder 30 is F. Also, L is the distance between the link plate fulcrum shaft 17 and the guide shaft 33 . The distance L is constant. This conflicts with the power increase rate in the vicinity of the clamping point in the toggle clamping mechanism, so a rapid increase in the clamping force can be suppressed.

As shown in FIG. 3 or 4, the angle between the contact surface W1 of the workpiece W and the wear limit point M2 of the wear margin M1 of the contactor A1 of the arm 12 is widened around the axis of the arm rotation shaft 16. Let the angle be θ2. The wear limit point M2 is the final position where the contactor A1 can be interposed between the arm 12 and the contacted surface W1. When the wear of the contactor A1 progresses beyond the wear limit point M2, the arm 12 comes into contact with the contacted surface W1. The opening angle θ2 at the time of unclamping is 45°. Also, the link angle θ1 is 90°. Furthermore, the link angle θ3 is 95°.

During unclamping, the guide shaft 33 and the second cam follower 35 are positioned on the opposite side of the first groove 21 to the second groove 22 . As the cylinder 30 protrudes, the guide shaft 33 moves through the guide groove 20 from the opposite side of the first groove 21 to the second groove 22 toward the second groove 22 . The guide shaft 33 applies a moment to the link plate action shaft 19 via the link plate 13 . Then, the moment acting on the link plate action shaft 19 around the link plate fulcrum shaft 17 generates a moment on the link rotation shaft 12a. That is, in the link plate 13, the link plate fulcrum shaft 17 functions as a fulcrum, the guide shaft 33 functions as a power point, and the link plate action shaft 19 functions as an action point.

The guide shaft 33 contacts the guide groove 20 of the auxiliary plate 15 via the second cam follower 35 and contacts the cam groove 23 of the link plate 13 via the first cam follower 34 . The second cam follower 35 follows the trajectory of the guide groove 20 of the auxiliary plate 15 to define the position where the first cam follower 34 contacts the cam groove 23 of the link plate 13 . When viewed from the side of the auxiliary plate 15 , the first groove 21 of the guide groove 20 forms an arc around the link plate fulcrum shaft 17 . As a result, when the guide shaft 33 moves within the guide groove 20 to the state shown in FIGS. to push the cam groove 23 to swing the link plate 13 . Then, the link plate 13 swings around the link plate fulcrum shaft 17 so that the link plate action shaft 19 approaches the arm 12 . As a result, the link member 14 swings with the link plate action shaft 19 as the swing center, and the arm 12 swings toward the workpiece W. As shown in FIG. At this time, the distance L between the guide shaft 33 and the link plate fulcrum shaft 17 is constant, the same as during unclamping.

As shown in FIGS. 6, 7, 10, and 11, at the intermediate position where the guide shaft 33 and the second cam follower 35 have moved to the boundary between the first groove 21 and the second groove 22, the contact A1 of the arm 12 The opening angle θ2 between the wear limit point M2 of the contact surface 120 and the contacted surface W1 of the work W is 2.5°. At this time, the contactor A1 is not worn, and is in a clamped state in which the contact surface 120 of the contactor A1 and the contacted surface W1 of the workpiece W are in contact with each other. At this time, the link angle θ1 is 25 degrees short of 180 degrees. That is, the link angle θ1 is smaller than when the center of the link rotation shaft 12a, the center of the link plate fulcrum shaft 17, and the center of the link plate action shaft 19 are aligned on the same straight line. In this embodiment, the clamping force is set to 15 kN when the opening angle θ2 is 2.5°. The clamping force when the opening angle θ2 is 2.5° is appropriately set according to the workpiece W to be clamped.

When the clamp device 10 is used in the state shown in FIG. 6 or 7, the contactor A1 of the arm 12 wears out. As the number of uses of the clamping device 10 increases, the wear margin M1 of the contactor A1 becomes smaller. Then, as the wear of the contactor A1 progresses, the opening angle θ2 decreases to approach 0°. Also, the link angle θ1 increases to approach 170°.

At the time of initial setting, the link angle shown in FIG. 6 or 7 is the clamped state. However, when the wear of the wear margin M1 of the contactor A1 progresses, the clamping state is not achieved in the state of the link angle shown in FIG. 6 or 7 .

A state in which the contact surface 120 of the contactor A1 reaches the wear limit point M2 will be described. The guide shaft 33 and the second cam follower 35 protrude into the second groove 22 of the guide groove 20 . Therefore, the guide shaft 33 projects from the first groove 21 into the second groove 22 before the clamping force reaches its maximum. Furthermore, when the guide shaft 33 is moved along the second groove 22 from the intermediate position by the cylinder 30, the guide shaft 33 moves along the cylinder 30 because the second groove 22 extends linearly with respect to the cylinder 30. move in a straight line with respect to At this time, the second cam follower 35 rotates while contacting the guide groove 20 , and the first cam follower 34 rotates while contacting the cam groove 23 . Then, the cylinder 30 swings about the guide shaft 33 as the swing center. At the same time, since the first cam follower 34 contacts the cam groove 23 as the guide shaft 33 moves, the link plate 13 swings around the link plate fulcrum shaft 17 so as to approach the arm 12 from the intermediate position. Also, the angle θ1 while the guide shaft 33 is in contact with the second groove 22 changes from 155° to approach 170°.

Then, the arm 12 is swung toward the workpiece W by swinging the link member 14 from the intermediate position about the link plate action shaft 19 as the swing center. Then, the work W is clamped by the arm 12 . Thereby, the clamping force is increased more than the intermediate position. That is, in the arm 12, the arm rotation shaft 16 functions as a fulcrum, the link plate action shaft 19 functions as a force point, and the link rotation shaft 12a functions as an action point. At this time, the distance L between the guide shaft 33 and the link plate fulcrum shaft 17 becomes larger than that at the time of unclamping and the intermediate position. Therefore, by providing the cam groove 23, the distance L between the guide shaft 33 and the link plate fulcrum shaft 17 during clamping is made longer than the distance L between the guide shaft 33 and the link plate fulcrum shaft 17 during unclamping. formed.

The state shown in FIG. 6 or FIG. 7 is a state in which the second cam follower 35 reaches the second groove 22 from the first groove 21 in the track of the guide groove 20 of the auxiliary plate 15 . At this time, the first cam follower 34 is positioned in a portion of the cam groove 23 of the link plate 13 near the link plate fulcrum shaft 17 . In the operation up to this point, the first groove 21 holds the first cam follower 34 , that is, the guide shaft 33 in a portion of the cam groove 23 closer to the link plate fulcrum shaft 17 . Therefore, the engagement position of the guide shaft 33 with respect to the cam groove 23 is determined by the engagement between the guide groove 20 and the guide shaft 33 .

When the operation of the cylinder 30 further progresses from here, in the trajectory of the guide groove 20 of the auxiliary plate 15, the second cam follower 35 contacts the first cam follower 34 and the cam groove 23 of the link plate 13 at the link plate fulcrum axis. It advances in the second groove 22 so as to gradually move away from 17 .

The contact position between the first cam follower 34 and the cam groove 23 moves away from the link plate fulcrum shaft 17 . As a result, the distance L between the guide shaft 33 and the link plate fulcrum shaft 17 increases. On the other hand, the link angle θ3 is set to be smaller than 90°. As a result, the moment applied to the work W gradually decreases. That is, as the link angle θ1 approaches 180°, it becomes difficult to rapidly increase the amplification factor of the clamping force.

As shown in FIGS. 10 and 11, the link angle θ1 and the opening angle θ2 in the states shown in FIGS. 3 and 4 correspond to point P1. Similarly, the link angle θ1 and the opening angle θ2 in the states shown in FIGS. 6 and 7 correspond to point P2. The link angle θ1 and the opening angle θ2 in the state shown in FIGS. 8 and 9 correspond to point P3.

The state shown in FIG. 6 or 7 corresponds to point P2, which is the breaking point of the curve that rises gently from the curve that rises sharply near 1.5 kN, as shown by the solid line in FIGS. . The point P2 corresponds to the initial setting in consideration of wear of the wear margin M1 of the contactor A1.

8 or 9, as shown in FIGS. 10 and 11, the wear margin M1 of the contactor A1 progresses and the link angle .theta.1 becomes 170 degrees. The second cam follower 35 and the second groove 22 of the guide groove 20 of the auxiliary plate 15 allow the first cam follower 34 to be positioned slightly in front of the cam groove 23 of the link plate 13 on the side away from the link plate fulcrum shaft 17. is set. Therefore, the engagement position of the guide shaft 33 with respect to the cam groove 23 is determined by the engagement between the guide groove 20 and the guide shaft 33 .

When the fulcrum, force point, and action point of the link mechanism are aligned on the same straight line, that is, at the dead point where the link angle θ1 is 180°, when the contact position between the first cam follower 34 and the cam groove 23 is displaced, the clamping force becomes 0. Therefore, before the clamping force becomes 0, that is, at the position where it becomes 170° as shown in FIGS.

The state shown in FIG. 8 or 9 is the position just before the clamping force reaches its maximum. It is adjusted in advance so that the first fastener 11a and the second fastener 12b are in contact with each other. Therefore, the operator can confirm this position by confirming the gap between the first fastener 11a and the second fastener 12b.

8, 9 or 11, when the guide shaft 33 and the second cam follower 35 move to the end of the second groove 22 opposite to the first groove 21, the contactor A1 of the arm 12 is The opening angle θ1 between the contact surface 120 and the contacted surface W1 of the workpiece W is 0°. In this embodiment, assuming that the opening angle θ1 is 0° during clamping, the clamping force during clamping is set to 15 kN or more. The distance L between the guide shaft 33 and the link plate fulcrum shaft 17 during clamping is maximum. The contact surface 120 of the contactor A1 of the arm 12 is in contact with the contact surface W1 of the workpiece W. As shown in FIG. A second fastener 12 b provided on the arm 12 is in contact with a first fastener 11 a provided on the main body 11 . Moreover, the opening angle θ2 at this time is smaller than 180°.

In this embodiment, the clamping device 10 can exert a clamping force when the opening angle θ2 is in the range of 0° to 2.5°.
In the above embodiment, the following effects can be obtained.

(1) Since the clamping device 10 has the cam groove 23, the clamping force can be gradually increased. Also, the cam groove 23 is pushed by the guide shaft 33 projecting from the first groove 21 into the second groove 22 before the opening angle θ2 becomes 0°. Thereby, the clamping device 10 can clamp the work W with a predetermined clamping force even if the opening angle θ2 is before 0°. Therefore, the range in which the clamping device 10 can secure the clamping force can be widened.

The clamping device 10 can clamp the workpiece W with a predetermined clamping force when the opening angle θ2 is in the range of 0° to 2.5°. Therefore, even if the contactor A1 of the arm 12 has a wear margin M1, the work W can be clamped with a predetermined clamping force. Further, since it is not necessary to set a large wear margin M1 for adjustment after the contactor A1 is worn, adjustment of the positional relationship between the work W and the contact surface 120 is facilitated.

(2) As the second groove 22 extends away from the first groove 21, it extends away from the extension line along the arc of the first groove 21, so the guide shaft 33 is guided by the second groove 22 and moves. As it increases, the distance L is lengthened and the clamping force is increased.

(3) Since the second groove 22 is provided in a straight line, for example, compared to the case where the second groove 22 is provided along the extension line of the arc of the first groove 21, the link is forcibly To rock the plate 13, the clamping force is increased.

(4) The radius of curvature of the arc of the cam groove 23 is smaller in the portion away from the link plate fulcrum shaft 17 than in the portion located closer to the link plate fulcrum shaft 17 . According to this, the moment applied to the workpiece W is gradually reduced. Therefore, it is possible to suppress a sudden increase in the clamping force.

(5) Since the second grooves 22 are provided in a straight line, workability is improved compared to, for example, the case where the second grooves 22 are provided in a complicated shape.
It should be noted that the above embodiment can be implemented with the following modifications. The above embodiments and the following modifications can be combined with each other within a technically consistent range.

- In the embodiment, the cam groove 23 is provided in an arc shape, but may be provided in a straight line, for example. In short, any shape may be used as long as the guide shaft 33 is guided while increasing the clamping force when it enters the second groove 22 .

- Although the 2nd groove|channel 22 is provided in linear form in embodiment, it may be provided, for example circularly. In short, any shape may be used as long as the guide shaft 33 is guided while increasing the clamping force when it enters the second groove 22 .

- In the embodiment, the angle θ1 may be 180° when the opening angle θ2 is 0°. The point is that the clamping force is maximized when the opening angle θ2 is 0°.

DESCRIPTION OF SYMBOLS 10... Clamp device 11... Main body 12... Arm 12a... Link rotating shaft 13... Link plate 14... Link member 14a... First end 14b... Second end 15... Auxiliary plate 16... Arm rotation Axes 17 Link plate fulcrum shaft 19 Link plate action shaft 20 Guide groove 21 First groove 22 Second groove 23 Cam groove 30 Cylinder as an actuator 33 Guide shaft Reference numerals 120: Contact surface, L: Distance, W: Work, W1: Contacted surface, θ1: Link angle, θ2: Opening angle, θ3: Link angle.

Claims (6)

the main body;
an arm swingably supported by the main body by an arm rotation shaft;
a link plate swingably supported by the main body by a link plate fulcrum shaft;
a link member having a first end swingably supported with respect to the link plate by a link plate action shaft and having a second end swingably supported with respect to the arm by a link rotation shaft;
an actuator;
a guide shaft linearly moved by the actuator relative to the actuator;
an auxiliary plate fixed to the body;
The auxiliary plate is provided with a guide groove through which the guide shaft is inserted to guide the guide shaft, and the link plate is provided with a cam groove through which the guide shaft is inserted,
The cam groove is formed such that the distance between the link plate fulcrum axis and the guide shaft during clamping is longer than the distance between the link plate fulcrum axis and the guide shaft during unclamping,
A clamping device, wherein an engagement position of the guide shaft with respect to the cam groove is determined by engagement between the guide groove and the guide shaft. The guide groove is
a first groove extending along an arc track centered on the link plate fulcrum axis;
2. The clamping device of claim 1, further comprising a second groove extending continuously from said first groove. 3. The clamping device of claim 2, wherein said second groove extends away from an arc extending along said first groove as it extends from said first groove. The cam groove is arcuate,
4. A radius of curvature of the cam groove is smaller at a portion of the cam groove located away from the link plate fulcrum shaft than at a portion of the cam groove located closer to the link plate fulcrum shaft. A clamping device as described in . The clamping device according to any one of claims 2 to 4, wherein the second groove is provided linearly. The clamping device according to any one of claims 2 to 5, wherein clamping is performed in a state in which the guide shaft is positioned in the second groove of the guide groove.