CN1271640A - clamping device - Google Patents

Abstract

The invention relates to a clamping device, comprising: a cylinder unit (14) for moving a rod (32) arranged in a frame (12) in the axial direction of a frame (12), and a cylinder unit (14) The connecting plate (72) used to connect with the rod (32), the clamping device also includes a toggle connection mechanism (64) that converts the linear motion of the rod (32) into rotation, and a cylinder unit (14) ) is driven to rotate an arm lever (20) at a predetermined angle, and a guide roller (79) supported by the frame body (12), the guide roller (79) can rotate simultaneously with an arc surface of the connecting plate (72) (81) CONTACT.

Description

clamping device

The present invention relates to a clamping device capable of clamping a workpiece by using an arm rotatable by a predetermined angle in response to the driving action of a driving mechanism.

Clamping cylinders are currently used, for example, to clamp a component of a motor vehicle when this component is to be welded. Such a clamping cylinder is disclosed, for example, in US Patent No. 4,458,889.

The clamping cylinder disclosed in US Patent No. 4,458,889 is shown in FIGS. 22 and 23 . A piston rod 2 is arranged to move back and forth between a pair of detachable frame bodies 1a, 1b. A link 3 is connected to one end of the piston rod 2 . A pair of connecting rods 5a, 5b and a pair of rollers 6a, 6b are rotatably connected to both sides of the coupling member 3 by means of a first shaft 4, respectively. An arm 8 rotatable by a predetermined angle is connected by a second shaft 7 between the pair of links 5a, 5b.

In this arrangement, the pair of rollers 6a, 6b are arranged rotatable by means of a plurality of needles 9a mounted in a hole. The piston rod 2 is arranged to move integrally with the rollers 6a, 6b according to the guiding action of the rollers 6a, 6b sliding along the track grooves 9b formed on the frame bodies 1a, 1b, respectively.

However, the clamp cylinder disclosed in US Pat. No. 4,458,889 involves conventional technology, which has the following disadvantages. That is, when a not-shown workpiece is clamped by the arm 8, the clamping force is reduced due to the change in the rotational angle of the arm 8.

In the case of the clamping cylinder described above, the reaction force generated when the workpiece is clamped by the arm 8 is applied to the first shaft 4 . Therefore, it is necessary to consider, for example, surface pressure and strength when designing the diameter of the first shaft 4 . As a result, there arises a disadvantage that the diameter of the first shaft 4 increases.

In addition, the surface pressure and strength of the pair of rollers 6a, 6b that must slide along the track groove 9b are designed when the wall thickness and diameter of the rollers 6a, 6b are designed. As a result, the following disadvantages arise. That is, the shape of the pair of rollers 6a, 6b becomes larger, and thus the size of the frame bodies 1a, 1b also increases.

A general object of the present invention is to provide a clamping device which maintains a substantially constant clamping force even when the angle of rotation of the arm varies when clamping a workpiece.

A main object of the present invention is to provide a clamping device which can reduce the diameter of a hook pin by using a guide roller to absorb the reaction force generated during clamping.

Another object of the present invention is to provide a clamping device that can achieve a smaller size frame.

The above and other objects, features and advantages of the present invention will become more clearly understood from the following description taken in conjunction with the accompanying drawings, in which a preferred embodiment of the invention is shown by way of example.

1 is a perspective view showing a clamping device according to an embodiment of the present invention;

2 is a perspective view showing a state where a cover is separated from a frame of the clamping device;

Fig. 3 is a longitudinal sectional view along line III-III in Fig. 1;

Fig. 4 is a cross-sectional view along line IV-IV in Fig. 3;

Fig. 5 is an exploded perspective view showing the frame body of the construction clamping device;

Fig. 6 is a partial cross-sectional view illustrating a variation of a guide roller;

Fig. 7 is a cross-sectional view along line VII-VII in Fig. 6;

Fig. 8 is the working state when a boom is in an initial position;

Fig. 9 shows a working state, wherein a rod moves upward from the initial position, and an arc surface of a connecting plate is in contact with the guide roller.

Figure 10 shows the working state when the workpiece is clamped;

Fig. 11 shows a partially enlarged view, which shows a line for transmitting reaction force in the clamping cylinder of the conventional technology;

Fig. 12 shows a partially enlarged view, which shows a route of reaction force transmission in the clamping cylinder of the embodiment of the present invention;

Fig. 13 shows an angle formed on the force point in the clamping cylinder of the conventional technology;

Figure 14 shows a state in which the arm lever moves by an angle θ from the state shown in Figure 13;

Figure 15 shows an angle formed on the force point in the clamping device of the present invention;

Figure 16 shows a state in which the arm lever is moved by an angle θ from the state shown in Figure 15;

Fig. 17 shows the relationship between the rotation angle θ of the arm lever and the clamping force;

Fig. 18 shows the point of contact between the cambered surface of the connecting plate and the guide roller in the state where the arm bar rotates a θ ₃ angle with respect to the horizontal axis;

Fig. 19 shows the point of contact between the cambered surface of the connecting plate and the guide roller in the state where the arm bar rotates a θ ₄ angle relative to the horizontal axis;

Figure 20 shows the point of contact between the web camber and the guide rollers in a state where the arm is substantially in a horizontal position;

Figure 21 shows a partial longitudinal sectional view of a clamping device according to another embodiment of the present invention;

FIG. 22 is an exploded perspective view showing main parts of a conventional art clamp cylinder;

FIG. 23 shows a partial cutaway side view of the clamping cylinder shown in FIG. 22 .

Referring to Fig. 1, reference numeral 10 denotes a clamping device according to an embodiment of the present invention. The clamping device 10 comprises a frame body 12 with a flat structure, a cylinder unit (drive mechanism) 14 connected to the lower end of the frame body 12 in an airtight manner, and an arm lever 20 connected to a rectangular bearing portion 18, wherein The bearing portion protrudes through a pair of generally circular openings 16a, 16b (see FIG. 5 ) formed through the frame body 12 .

The cylinder unit 14 includes a base 24 having an unillustrated elliptical groove formed on its upper surface, and a cylinder tube 26 formed from a cylinder having an elliptical cross-section, wherein the first end of the cylinder ends in a It is connected to the groove of the base 24 in an airtight manner, and its second end is connected to the bottom surface of the frame body 12 in an airtight manner.

As shown in Figure 3, the cylinder unit 14 also includes a piston 30 that is installed in the cylinder tube 26 and reciprocates along a cylinder chamber 28, and a rod 32 that is connected to the middle of the piston 30 and can move together with the piston. And one is located on the connecting portion between the piston 30 and the rod 32 and is mounted on the ring 33 outside the rod 32 by a hole. The retaining ring 33 is made of metal material such as aluminum. The retaining ring 33 abuts against the wall of a projection 50 forming the upper part of the cylinder chamber 28 at the end position of the displacement of the piston 30 and thus acts as a stop for regulating the displacement of the piston 30 . Alternatively, the piston 30 and the retaining ring 33 are integrally formed as one unit.

As shown in FIG. 3 , a wear ring 34 and a piston seal 36 are installed on the outer peripheral surface of the piston 30 respectively. Connection holes, not shown, pass through the four corners of the base 24 . The base 24 and the cylinder tube 26 are mounted in the frame body 12 in a hermetically sealed manner by means of four shafts 40 passing through connecting holes (see FIGS. 1 and 2 ). Pairs of pressure fluid inlets/outlets 42a, 42b, 44a, 44b are used to respectively introduce and discharge pressure fluid (such as compressed air) relative to the cylinder chamber 28, and these pressure fluid inlets/outlets are respectively formed on the frame body 12 opposite to each other. and base 24.

When the clamping device 10 is actually used, flange covers, not shown, are screwed into any pair of pressurized fluid inlets/outlets 42a, 44a (42b, 44b). Thus, the clamping device 10 is used in a state where one of the pair of pressurized fluid inlets/outlets 42a, 44a (42b, 44b) is closed.

As shown in FIG. 5, the frame body 12 includes a first cover plate 46 and a second cover plate 48, which are asymmetrical and assembled in an integral manner. A projection 50 protrudes a predetermined length in a substantially horizontal direction and functions as a rod cover, and the projection 50 is integrally formed on the lower end of the first cover plate 46 . Compared with the first cover plate 46, the second cover plate 48 has a dimension shortened by the thickness of a projection 50 in the longitudinal direction, as shown in FIG. The lower second cover plate 48 can be easily disassembled without disassembling the cylinder unit 14 .

As shown in Figure 5, a chamber 54 is formed in the frame body 12 by grooves 52a, 52b formed respectively for the first cover plate 46 and the second cover plate 48 (the groove 52b is omitted in the figure because it has the same The same structure as groove 52a). The free end of the rod 32 is arranged facing the chamber 54 . In this arrangement, the rod 32 is guided linearly and reciprocally by means of the guide groove 58 . Guide grooves 58 are respectively formed on the inner walls of the first cover plate 46 and the second cover plate 48, and a toggle block 56 is slidable on the guide grooves 58, which will be described below. A rod seal 60 (see FIG. 3 ) surrounds the outer peripheral surface of the rod member 32 , and the rod seal 60 is provided in a through hole formed in the projection 50 .

As shown in FIG. 5 , a toggle linkage mechanism 64 is provided on the first end of the lever 32 for converting the linear motion of the lever 32 into the rotation of the arm 20 by means of the toggle 62 . Knuckle 62 includes a knuckle block 56 and a knuckle pin 70, the knuckle block has a fork with branches, the branches are separated by a predetermined spacing distance and are substantially parallel to each other, the knuckle pin 70 is rotatably connected to formed in a hole in the fork.

As shown in FIG. 5 , a groove 68 with a T-shaped cross section is formed on a bottom surface of the toggle block 56 and extends substantially in the horizontal direction, and a disc-shaped boss 66 of the rod 32 fits into the groove 68 . In this arrangement, predetermined gaps are formed between the groove 68 and the boss 66 integrally formed with the rod 32 and between the toggle block 56 and the guide groove 58 . The toggle block 56 is configured to move substantially horizontally along the slot 68 . In this way, the bar 32 is prevented from transmitting any loads in the transverse direction. In other words, by providing a degree of freedom to the toggle block 56, for example, when the workpiece is clamped, no lateral loads are applied to the rod 32 and the rod seal 60, for example, and the stroke of the rod 32 can be efficiently transmitted Give toggle linkage 64.

As shown in Figure 5, the toggle link mechanism 64 includes a connecting plate (connecting rod) 72 connected to the fork of the toggle 62 by means of a toggle pin 70, and a connecting plate (link member) 72 which passes through the first cover plate respectively. 46 and the second cover plate 48 form a pair of substantially circular openings 16a, 16b rotatably supported by a support rod 74 .

The connecting plate 72 may be inserted between the toggle joint 62 and the support rod 74 and may connect the toggle joint 62 and the support rod 74 . Specifically, the connecting plate 72 is provided with a pair of holes 76a, 76b separated from each other by a predetermined spacing distance. The connecting plate 72 is connected to the free end of the rod member 32 by the toggle joint 62, and the toggle pin 70 is rotatably connected to the first hole 76a. The connecting plate 72 is connected to the fork portion of the support rod 74 by a connecting pin 78 rotatably connected to the second hole 76b. An arcuate surface 81 contacting a guide roller (rotation means) 79 as described below is formed on a first end of the connecting plate 72 provided near the first hole 76a.

As shown in Figure 5, the support rod 74 includes a fork that is provided with a hole that is rotatably connected to the connecting pin 78, protrudes in a direction substantially perpendicular to the axis of the rod member 32 and has an opening 16b from the frame body 12 outside. A visible bearing portion 18 of a rectangular cross-section, a pair of peripheral portions 80a, 80b respectively located near the fork-shaped portion sandwiched therebetween and mounted on the substantially circular openings 16a, 16b of the frame body 12, And a pair of circular arc-shaped protrusions 82a, 82b slightly protruding from the peripheral portions 80a, 80b in the transverse direction and exposing the frame body 12 through the openings 16a/16b. An arm 20 for clamping a workpiece not shown is detachably attached to the bearing portion 18 .

The support rod 74 is configured to be integrally rotatable with the arm rod 20 . The arc-shaped protrusions 82a, 82b formed on the support rod 74 are close to the plates 84a, 84b fixed on the frame body 12 . Therefore, the arc-shaped protrusions 82a, 82b function as stops that prevent the arm lever 20 from rotating.

The linear movement of the rod 32 is transferred to the support rod 74 by the toggle joint 62 and the connecting plate 72 . The support rod 74 is provided so as to be rotatable by a predetermined angle around the center of rotation of the peripheral portions 80a, 80b supported by the pair of openings 16a, 16b formed by the frame body 12. As shown in FIG.

As shown in FIG. 5 , oval grooves 86 are respectively formed on the side surfaces of the first cover plate 46 and the second cover plate 48 constituting the frame body 12 . The slot 86 is closed by a pair of covers 88a, 88b. The cover pieces 88 a , 88 b are detachably attached by means of bolt pieces 89 . In this arrangement, the bearing portion 18 of the support plate 74 is arranged to be exposed outside through a substantially circular opening 90 formed in a substantially central portion of the cover member 88b.

Plates 84 a , 84 b that can abut against the arc-shaped projections 82 a , 82 b of the support rod 74 to prevent the rotation of the arm rod 20 are detachably fixed on the arm surface of the slot 86 by means of bolts 92 .

As shown in Figure 5, the plate 84b (84a) has a first abutting surface 96 that can abut against a first end surface 94 of the arc-shaped protrusion 82b (82a), and a first abutting surface 96 that can abut against the arc-shaped protrusion 82b (82a) a second abutting surface 100 of a second end surface 98. An arcuate surface 102 surrounding the support rod 74 is formed between the first abutment surface 96 and the second abutment surface 100 . The first end surface 94 and the second end surface 98 of the support rod 74 are formed to be spaced from each other at an angle of about 90°. Of course, the separation angle of the first end surface 94 and the second end surface 98 is not limited to an angle of 90°.

In this arrangement, the pair of plates 84a, 84b can be easily interchanged with other plates by removing the pair of cover members 88a, 88b respectively from the frame body 12 and loosening the bolt members 92 (described below). When the pair of covers 88a, 88b are removed from the frame body 12, the first end surface 94 and the second end surface 98 of the arc-shaped protrusion 82b (82a) formed on the support rod 74 are exposed outside as shown in FIG. (However, the first end face 94 is not shown).

As shown in FIG. 5 , grooves 106 having an arc-shaped cross section are respectively formed on the upper side portions of the inner wall surfaces of the first cover plate 46 and the second cover plate 48 constituting the frame body 12 . Guide rollers 79 that are rotated by a predetermined angle by contacting the arcuate surface 81 of the connecting plate 72 are provided in the groove 106 . A pin member 110 rotatably supporting the guide roller 79 is mounted on the hole 108 in the first cover plate 46 and the second cover plate 48 . A plurality of needle bearings 112 are installed in a through hole of the guide roller 79 in the circumferential direction. The guide roller 79 is provided so as to be able to rotate smoothly according to the rolling action of the needle bearing 112 .

Alternatively, another arrangement may be provided as shown in FIG. 6 or 7 . That is, a pin shaft member 114 can be arranged to be in direct contact with the arc-shaped surface 81 of the connecting plate 72 . Both ends of the pin shaft member 114 are respectively rotatably supported by a plurality of short needle bearings 118 mounted on the cover members 116a, 116b.

As shown in FIG. 5 , the pair of guide grooves 58 consisting of rectangular grooves and extending in the vertical direction are arranged oppositely on the inner wall surfaces of the first cover plate 46 and the second cover plate 48 . The toggle block 56 is sandwiched between the pair of guide grooves 58 . The toggle block 56 is configured to slide in the vertical direction according to the guiding effect of the guide groove 58 .

The clamping device 10 of this embodiment of the present invention is basically constructed as described above. How it works and what it does is described below.

First, the clamping device 10 is fixed at a predetermined position by an unshown fixing device. First ends of connecting pipes such as unshown pipes are respectively connected to the pair of pressure fluid inlets/outlets 42a, 44a (42b, 44b). The second end of the connecting tube is connected to a not shown supply of pressurized fluid. FIG. 8 shows the clamping device 10 in an unclamped state, while FIG. 10 shows the clamping device 10 in a clamped state. In the following description, the unclamped state in FIG. 8 is considered to represent an initial position.

After carrying out the above preparatory work, the pressure supply source not shown is powered in the initial position as shown in FIG. 30 in the cylinder cavity 28 on the underside. The piston 30 is compressed according to the compressed fluid introduced into the cylinder chamber 28 . Piston 30 moves upwardly along cylinder cavity 28 .

The linear motion of the piston 30 is transmitted to the toggle link mechanism 64 by the rod member 32 and the toggle link mechanism 62 , and is transformed into the rotation of the arm rod 20 according to the rotation action of the support rod 74 constituting the toggle link mechanism 64 .

That is, the linear movement (upward movement) of the piston 30 allows a force to act such that the web 72 and the toggle 62 cooperating with the free end of the piston rod 32 are compressed in an upward direction. Due to the compressive force exerted on the connecting plate 72, the connecting plate 72 rotates by a predetermined angle around the supporting point of the toggle pin 70, and the supporting rod 74 rotates in the direction of arrow A according to the connecting action of the connecting plate 72.

Accordingly, the arm 20 is rotated by a predetermined angle in the arrow B direction about the support point of the bearing portion 18 of the support rod 74 . Correspondingly, the arc-shaped protrusion 82b ( 82a ) and the supporting rod 74 integrally rotate by the predetermined angle.

When the arm 20 is rotated in the arrow B direction as described above, the arcuate surface 81 of the connecting plate 72 is brought into contact with the guide roller 79 as shown in FIG. 9 . The guide roller 79 rotates around the center of the pin member 110 while maintaining a state of being in contact with the arcuate surface 81 .

The arm lever 20 rotates further, and the first end surface 94 of the arc-shaped protrusion 82b (82a) abuts against the first abutting surface 96 of the plate 84b (84a) fixed on the frame body 12, as shown in FIG. 10 . Correspondingly, the arm prevents the rotational action. As a result, a clamped state in which the workpiece is clamped by the arm 20 is determined.

After the arm 20 resists the rotational action to establish the clamped state, the piston 30 and the rod 32 move slightly further upwards. The retaining ring 33 abuts against the wall of the protrusion 50 . Correspondingly, the piston 30 and the rod 32 come to a standstill giving the end positions of the movement (see FIG. 3 ).

On the other hand, when the pressurized fluid is supplied to the pressurized fluid inlet/outlet 42a in accordance with the steering action of an unillustrated switching valve in the state shown in FIG. 3, the piston 30 moves downward. In addition, the support rod 74 is rotated in a direction opposite to the above-mentioned direction by means of the connecting plate 72 according to the downward movement of the rod member 32 . Accordingly, the arm 20 rotates in a direction away from the workpiece.

During the rotation of the arm lever 20 in this direction to separate from the workpiece, the second end surface of the arc-shaped protrusion 82b (82a) abuts against the second abutment surface of the plate 84b (84a) fixed on the frame body 12 100. Correspondingly, the arm 20 resists the turning action. As a result, the clamping device 10 returns to the original position shown in FIG. 8 .

Next, description will be made regarding the case where the reaction force generated corresponding to the clamping force is balanced with the force to be balanced therewith when the workpiece is clamped.

In the case of the clamp cylinder related to the conventional art, as shown in FIG. 11, when the workpiece is clamped, a reaction force is generated in a direction opposite to the clamping force. The reaction force is transmitted by the arm lever 8 to the second shaft 7, and further transmitted by the link 5a, 5b to the pair of rollers 6a, 6b rotatably supported by the first shaft 4, to balance the force with the reaction force balance. Therefore, in the case of the conventional art clamp cylinder, a force corresponding to the reaction force is applied to the first shaft 4 that rotatably supports the pair of rollers 6a, 6b. For this, the first shaft must be designed with a larger diameter.

On the contrary, in the case of the embodiment of the present invention, as shown in FIG. 12 , the reaction force is transmitted from the arm bar 20 to the connecting pin shaft 78 , and further transmitted to the guide roller 79 in contact with the arc surface 81 of the connecting plate 72 . In this arrangement, the guide rollers 79 are rotatably supported by pin members 110 mounted in the holes 108 of the first cover plate 46 and the second cover plate 48 . The reaction force transmitted to the guide roller 79 is applied to its pin member 110 attached to the first and second cover plates 46,48.

Therefore, embodiments of the present invention are designed so that the force corresponding to the reaction force is not applied to the toggle pin 70 at all. Accordingly, the diameter of the toggle pin 70 can be reduced. Furthermore, the bearing capacity of the connection between the toggle block 56 and the web 72 can be improved.

In the conventional technique, the width and diameter of the rollers 6 a , 6 b must be designed in consideration of the surface pressure and strength of the pair of rollers 6 a , 6 b sliding on the track groove 96 . On the contrary, in the embodiment of the present invention, such a design is not required, so a smaller-sized frame body 12 can be realized.

Next, the angle formed at the force point when the workpiece is clamped is described.

In the clamping cylinder of conventional technology, θ ₁ represents the angle formed on the force point in the state where the workpiece is clamped by the arm rod 8 in a substantially horizontal state (see Figure 13), and θ ₂ represents the angle formed during the clamping process The angle formed on the force point when the angle of the arm lever 8 changes clockwise by an angle of θ (see FIG. 14 ). As is clear from a comparison between Figs. 13 and 14, in the case of the conventional technique, when the rotation angle of the arm 8 is changed during workpiece clamping, the angles (θ ₁ , θ ₂ ) formed at the force point are greatly changed.

On the contrary, in the embodiment of the present invention, even when the workpiece is clamped, the angle of rotation of the arm 20 is formed from the point of application of force in a state where the workpiece is clamped by the arm 20 in a substantially horizontal state (see FIG. 15 ). The θ ₁ angle is changed to the θ ₂ angle (see Figure 16) and remains substantially constant.

Thus, it can also be clearly understood from FIG. 17 that the clamping force of the embodiment of the present invention is substantially constant even when the rotation angle of the arm 20 is increased (solid line). On the contrary, the conventional technique (dotted line) has the disadvantage that the clamping force decreases very quickly when the swivel angle of the arm 8 increases.

Therefore, the embodiments of the present invention have the following effects. That is, a substantially constant clamping force can be obtained even when the device is configured such that the workpiece is clamped by the arm 20 at a desired angle of rotation depending on, for example, the user's usage conditions.

Furthermore, in the embodiment of the present invention, a stop ring 33 for adjusting the terminal position of the displacement of the piston 30 is provided on the connecting portion between the rod 32 and the piston 30 inside the cylinder unit 14 . Accordingly, intrusion into the top dead center (dead point) can be reliably avoided by a simple structure.

Next, an arrangement in which the contact portion between the arcuate surface 81 of the connecting plate 72 and the guide roller 79 is maintained at a substantially constant position regardless of the rotation angle of the arm 20 will be described with reference to FIGS. 18 to 20 .

FIG. 18 shows a state in which the arm lever 20 is rotated from the unclamped initial position to clamp the workpiece at an angle _θ3 with respect to the horizontal axis. FIG. 19 shows a state in which the arm lever 20 is further rotated from the state shown in FIG. 18 to clamp the workpiece at an angle _θ4 with respect to the horizontal axis. FIG. 20 shows a state in which the arm 20 clamps the workpiece in a substantially horizontal state.

In the arrangement shown in FIGS. 18 to 20, a long hole 119 serving as a contact position holding mechanism is formed in the connecting plate 72 so that the toggle pin 70 fits into the long hole 119. An elongated hole 119 is formed in the plate 72 for releasing the toggle pin 70 . Accordingly, the contact portion between the guide roller 79 formed on the connecting plate 72 and the arcuate surface 81 is maintained in a substantially constant position regardless of the angle of the arm 20 .

The degree of freedom of the toggle pin 70 is ensured, and the center point of the toggle pin 70 can be set on the extension line of the axis T of the rod member 32 . As a result, the linear accuracy of the rod 32 can be effectively maintained, and the durability of the cylinder unit 14 can be improved.

The portion of contact between the arcuate surface 81 and the guide roller 79 actually depends on the line-line contact. However, in the circles 18 to 20, the contact portion is represented by a contact point P for convenience of expression. The position of the contact point P is represented by an X coordinate and a Y coordinate (X, Y), where the origin O is assumed to be the center of rotation of the arm 20 .

It can be clearly understood from FIGS. 18 to 20 that even when the rotation angle of the arm lever 20 is changed, the contact point P between the guide roller and the arcuate surface 81 of the connecting plate 72 is always the same and always in a constant position. (X,Y). Therefore, further linear clamping characteristics can be obtained, such that the clamping force is substantially constant and consistent with the arm lever 20 by maintaining a constant position at the contact point P between the guide roller 79 and the arcuate surface 81 of the connecting plate 72. The angle of rotation is irrelevant in order to avoid any wear on the contact between the connecting rod 72 and the guide roller 79 .

In FIGS. 18 to 20 , the origin O of the rectangular coordinate system is set at the center of rotation of the arm 20 . However, it is of course also possible to use the center of rotation of the guide roller 79 as the origin O.

Next, a clamping device 120 according to another embodiment of the present invention is shown in FIG. 21 . Components identical to those of the clamping device 10 shown in FIG. 3 are designated with the same reference numerals and will not be described in detail here.

The clamping device 120 has the following features. That is, a boss 126 is coaxially connected to the piston 24 at a side opposite to a piston 124 on which a rod 122 is provided. A locking mechanism 132 is arranged to lock the piston 124 using a pair of balls 130a, 130b that engage an annular groove 128 of the boss 126 .

The locking mechanism 132 has a pair of pressing parts 136a, 136b that press the balls 130a, 130b to the annular groove 128 according to the elastic force of the spring parts 134a, 134b, and it functions to keep the arm bar 20 at the initial position. The provision of the locking mechanism 132 has the following advantages. That is, even when the piston 124 can be in a free state by discharging pressurized fluid from the cylinder chamber 28, the piston 124 is in a locked state and can be prevented from moving. Therefore, rotation of the arm 20 can be prevented, and the arm 20 can be locked at the initial position.

In an embodiment of the invention, a cylinder is used as the drive mechanism. But it is not limited to this. Also preferably the lever 32 is moved by using, for example, a not shown linear actuator or an electric motor.

Claims (10)

1. A clamping device comprising: A frame (12); a driving mechanism (14) for moving a rod (32) arranged in the frame (12) in the axial direction of the frame (12); a toggle connection (64) comprising a connecting member (72) connected to said rod (32) for converting linear motion of said rod (32) into rotation; An arm lever (20) connected to the toggle connection mechanism (64) and rotated by a predetermined angle according to a driving action of the driving mechanism (14); A rotating part (79, 114) supported by the frame body (12), the rotating part (79, 114) can rotate and contact with the connecting part (72) at the same time. 2. The clamping device according to claim 1, characterized in that, the rotating member comprises a guide roller ( 79). 3. Clamping device according to claim 1, characterized in that said rotating member comprises a pin member (114) rotatably arranged by means of a bearing member (116a, 116b, 118). 4. The clamping device of claim 1, wherein the drive mechanism includes at least one cylinder. 5. The clamping device according to claim 1, characterized in that, an arc-shaped cross-section with a predetermined radius of curvature is formed at one end of the connecting piece (72) for connecting with the rotating piece (79) , 114) arc-shaped surface (81) in contact. 6. Clamping device according to claim 1, characterized in that it further comprises a clamp for holding between said connecting member (72) and said rotating member (79, 114) in a substantially constant position. A contact position maintaining mechanism irrespective of the rotation angle of the arm (20). 7. The clamping device according to claim 6, characterized in that, the contact position maintaining mechanism includes a device formed in the connecting piece (72) for being arranged on one end side of the rod (32) An elongated hole (119) that a elbow pin (70) cooperates. 8. The clamping device according to claim 6, characterized in that, a contact point between the connecting member (72) and the rotating member (79, 114) is maintained at ) or an origin (O) of the center of rotation of the rotating member (79, 114) is a substantially constant position (X, Y) determined by the X and Y coordinates. 9. Clamping device according to claim 4, characterized in that said cylinder is provided with a mechanism for holding said arm (20) in a predetermined position by locking said piston (124) in a predetermined position. The locking mechanism (132) in the unclamped state. 10. The clamping device according to claim 9, characterized in that, the locking mechanism (132) comprises a protrusion (126) coaxially connecting the piston (124) with the rod (122) ), a pair of balls (130a, 130b) for cooperating with an annular groove (128) formed on the boss (126), and a pair of balls (130a, 130b) that will The pair of balls (130a, 130b) press against the extrusion (136a, 136b) of the annular groove (128).

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