JP2002096230A - Clamp device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a clamp device to precisely position and to certainly fix a work without carrying out complicated electric control and without complicating a fluid supply circuit. SOLUTION: Three cylinders 4, 5, 6 concerning working mechanisms of three systems such as rising and lowering of a positioning pin 2, opening and closing of a clamp click 3 and extension and contraction of a piston rod 6a to fix the positioning pin 2 are arranged in the fluid supply circuit of one system. The two cylinders 4, 5 become serial arrangement of the cylinder 4 - the cylinder 5 in the fluid supply circuit of the one system at the time of working from the clamp state to the unclamp state. Additionally, it is possible to actuate the three cylinders 4, 5, 6 at proper timing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clamp device for performing positioning and fixing with reference to positioning holes formed in a work.

[0002]

2. Description of the Related Art For example, when welding a body panel,
A clamp device for accurately fixing a plurality of panels in a predetermined positional relationship is used. Since it is necessary to provide such a clamp device on a welding jig or the like dedicated to various types of vehicles, it is desirable that the clamp device has a simple structure. Moreover, it is necessary that the positioning accuracy and the fixing strength of the panel are sufficiently ensured.

FIG. 4 schematically shows a conventional clamping device 1. The clamp device 1 includes a clamp pin 2 for positioning and fixing the work W. The tip 2a of the clamp pin 2 is formed in a conical shape in order to facilitate insertion of the work into the positioning hole Wa. Further, a shoulder 2b for supporting the work W is formed at a predetermined distance from the tip 2a. And
A cylindrical portion 2c having the same diameter as the shoulder portion 2b is formed below the shoulder portion 2b, and a lower end portion of the cylindrical portion 2c is fixed to the cylinder 4.

The clamp pin 2 has a clamp claw 3 inside. The clamp claw 3 extends in the longitudinal direction within the cylindrical portion 2c of the clamp pin 2, and has a shape in which the tip 3a is bent in a hook shape. The lower end 3b of the clamp claw 3 is pivotally supported by a piston rod 4a of the cylinder 4 via a pivot shaft. In addition, clamp claws 3
Is a guide pin 2 fixed to the cylindrical portion 2c of the clamp pin 2.
It has a cam groove 3c that engages with d. Therefore, by lowering the piston rod 4a, the clamp pawl 3
And the distal end 3a can be made to protrude laterally from the slit-shaped opening 2e provided near the distal end 2a of the clamp pin 2. Also, the piston rod 4
When a is raised, as shown in FIG. 4, the clamp claw 3 can be raised and the tip 3 a can be stored inside the clamp pin 2.

The cylinder 4 is fixed to a piston rod 5a of the cylinder 5. Therefore, the clamp pin 2, the clamp claw 3, and the cylinder 4 can be integrally moved up and down by driving the cylinder 5.

Further, the cylinder 6 is arranged on the side of the cylinder 4 in a direction orthogonal to the cylinder 4. When the clamp pin 2, the clamp claw 3 and the cylinder 4 are raised by raising the piston rod 5 a of the cylinder 5 to the top dead center, the cylinder 4
, The piston rod 6a is projected below the cylinder 4 to prevent the clamp pin 2, the clamp claw 3 and the cylinder 4 from falling.
It has a fall prevention mechanism.

The pistons 4, 5, and 6 have piston rods 4.
Sensors 401, 402, 50 for detecting the positions of a, 5a, 6a
1,502,601,602 are provided. Also, cylinders 4, 5, 6
The solenoid valves 7, 9, 11 related to the operation of the above-mentioned and the supply sources 8, 10, 12 of the working fluid (here, air is used) are independently provided.

As described above, the conventional clamping device 1 shown in FIG. 4 has three operating mechanisms of a clamp pin 2, a clamp claw 3, and a fall prevention mechanism (piston rod 6a). The operating mechanism is driven by each of the cylinders 4, 5, and 6. Further, a plurality of cylinders 4, 5, 6 for driving the three-system operating mechanism,
Each is provided with three independent fluid supply circuits.

The procedure for clamping the work W is as follows. First, the piston rod 5a of the cylinder 5 is raised together with the clamp claw 3, the crank pin 2 is inserted into the positioning hole Wa of the work, and the work W is supported by the shoulder 2b. Subsequently, the piston rod 4a of the cylinder 4 is lowered to lower the clamp claw 3, and the tip 3a is projected from the side of the clamp pin 2. Then, the workpiece W is clamped by the shoulder 2b of the crank pin 2 and the tip 3a of the clamp claw 3. Also, by operating the cylinder 6,
The piston rod 6 a is projected below the cylinder 4 to prevent the clamp pin 2, the clamp claw 3 and the cylinder 4 from falling. When the work W is released, the operation procedure is completely opposite to the above.

The solenoids 7a, 7 of the respective solenoid valves 7, 9, 11 for driving the respective operating mechanisms in the above procedure.
The excitation timing of b, 9a, 9b, 11a, 11b and the operation timing of each air supply source 8, 10, 12 are determined by sensors 401, 402, 501, 50
It is electrically controlled based on the detection signals of the positions of the piston rods 4a, 5a, 6a by 2,601,602.

[0011]

As described above, the conventional clamping device 1 shown in FIG. 4 includes independent fluid supply circuits for sequentially operating the cylinders 4, 5, and 6 at a predetermined timing. ing. In such a structure, the number of sensors, solenoid valves, and working fluid supply sources is increased as the number of cylinders is increased. In addition, the position of each piston rod is detected by the sensors 401, 402, 501, 502, 601, 602, and based on the detection signals,
Each solenoid valve 7, 9, 11 and each supply source 8, 10,
Since the operation control of 12 is performed electrically, the electric circuit and the control contents are also complicated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a clamping device that drives a multi-system operating mechanism by a plurality of cylinders without performing complicated electrical control. Another object of the present invention is to perform accurate positioning and reliable fixing of a work without complicating a fluid supply circuit.

[0013]

According to a first aspect of the present invention, there is provided a clamp apparatus having a multi-system operating mechanism driven by a plurality of cylinders. The system is characterized by including a single fluid supply circuit for sequentially operating the plurality of cylinders at a predetermined timing.

In the clamp device according to the present invention, the plurality of cylinders can be sequentially operated at a predetermined timing by a single fluid supply circuit. Therefore, even if the number of cylinders increases due to the multi-system of the operating mechanism. The predetermined operation is performed without complicating the electric circuit and the control contents.

According to a second aspect of the present invention, in the clamping device, the plurality of cylinders are arranged in series in the one system of fluid supply circuit, and the plurality of cylinders are arranged downstream in accordance with a piston position of an upstream cylinder. It includes a valve structure that opens and closes a fluid supply circuit to the cylinder.

According to the present invention, the plurality of cylinders
After the upstream cylinder has operated by a predetermined amount in the fluid path of the position system, the downstream cylinder can be operated. Therefore, the plurality of cylinders can be sequentially operated at a predetermined timing without performing complicated electric control.

Further, in the clamp device according to a third aspect of the present invention, as the multi-system operating mechanism, a positioning pin that moves up and down, a clamp claw that fixes a work positioned by the positioning pin, and a drop of the positioning pin And a prevention mechanism.

The clamp device of the present invention positions the work by operating the positioning pin, fixes the work positioned by operating the clamp claws, and prevents the positioning pin from dropping by the fall prevention mechanism. This ensures accurate positioning and fixing of the work.

Further, in the clamp device according to a fourth aspect of the present invention, when in the unclamped state, the pressure fluid supplied to the fluid supply circuit drives a cylinder related to the elevation of the positioning pin, Raising the positioning pin, and then driving a cylinder that drives the clamp claws to clamp the work, and driving a cylinder of the positioning pin drop prevention mechanism to fix the positioning pin. It is.

The clamping device according to the present invention has three operating mechanisms for raising the positioning pin, clamping the work with the clamp claws, and fixing the positioning pin for clamping the work when in the unclamped state. Can be operated at a predetermined timing by the fluid supplied from one fluid supply source.

Further, in the clamp device according to claim 5 of the present invention, when in a clamp state, the pressure fluid supplied to the fluid supply circuit drives a cylinder of the mechanism for preventing the positioning pin from dropping, The fixing of the positioning pin is released, and the cylinder that drives the clamp pawl is driven to unclamp the workpiece. Subsequently, the cylinder related to the elevation of the positioning pin is driven to lower the positioning pin. It is characterized by making it.

In the clamp device of the present invention, when the clamp device is in the clamped state, the operation of releasing the fixing of the positioning pin, unclamping the work by the clamp pawl, and lowering the positioning pin for unclamping the work is performed.
The three cylinders according to the three-system operation mechanism can be operated at a predetermined timing by the fluid supplied from one fluid supply source.

[0023]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, the same parts and corresponding parts as in the prior art are denoted by the same reference numerals, and detailed description is omitted. In the following description, of the cylinder chamber of the cylinder, which is divided into two by a piston, the side that is filled with air during the extension operation is referred to as the “extension side”.
And the side that supplies air during the contraction operation is the “contraction side”
Is called.

FIG. 1 schematically shows a clamp device 1 according to an embodiment of the present invention. The clamp device 1 according to the present embodiment includes only one solenoid valve 13 and one air supply source 14, respectively. In addition, the clamp claw 3
The cylinder 4 related to the vertical movement of the crank pin 2 is arranged concentrically with the cylinder 5 related to the vertical movement of the crank pin 2, and the cylinder 4 itself is
It also functions as a piston rod 5a of the cylinder 5.

The piston rod 4a of the cylinder 4 is integrally mounted so as to protrude up and down of the piston 4c reciprocating in the cylinder chamber 4b, and forms a predetermined range from the lower end as a projecting pipe line 4d. . Further, a pipe 4e is fixed coaxially with the protruding pipe 4d. The piston 5c reciprocating in the cylinder chamber 5b of the cylinder 5 includes a sub-chamber 5d inscribing the outer peripheral wall of the protruding pipe 4d, and a protruding pipe 5f having an inner peripheral wall continuous with the sub-chamber 5d and circumscribes the pipe 4e.
And Further, a sub-chamber 5 g inscribed in the outer peripheral wall of the protruding pipe line 5 f is formed in the housing of the cylinder 5.

A cylinder 6 having a piston rod 6a which protrudes and retracts from the side in a sub chamber 5g is fixed to the housing of the cylinder 5. Cylinder chamber 6b of cylinder 6
A coil spring 6d is arranged on the extension side of
The piston rod 6a is pressed against a projecting pipe line 5f integral with the piston 5c.

Further, a first port 15 and a second port 16 are provided in the housing of the cylinder 5, and a solenoid valve 13 is provided.
Through the air supply source 14. 1st port 15
Communicates with the extension side of the cylinder chamber 5b of the cylinder 5. The cylinder chamber 6b of the cylinder 6 communicates with the second port 16 via a passage 19 formed in the housing of the cylinder 5.

The extension side of the cylinder chamber 5b is connected to the cylinder chamber 5c of the cylinder 4 via a sub-chamber 5g, a projecting pipe 5f, a pipe 4e, a projecting pipe 4d, and a passage 18 formed in the piston rod 4a. 4b communicates with the contraction side. Further, the extension side of the cylinder chamber 4b communicates with the second port 16 via a pipe 17 fixed to the housing of the cylinder 5. The extension side of the cylinder chamber 4b is connected to the sub chamber 5d.
And a passage 20 formed in the piston 5c and communicates with the contracted side of the cylinder chamber 5b. Then, in order to secure the tightness of the sliding surface of each member, seal 2
1, 22, 23, 24, 25, 26, 27 (there are other seals without reference numerals in FIG. 1). In addition, seal
For 24 and 26, packing (Y packing, U cup packing, etc.) having a check valve function is used for the reason described later.

Further, the clamp device 1 detects the proximity switch 31 for detecting that the piston rod 4a of the cylinder 4 is at the bottom dead center of the movable range and the proximity switch 31 for detecting that the piston 5c of the cylinder 5 is at the bottom dead center of the movable range. Reed switch to detect 32
And

Here, an operation procedure of the clamp device 1 according to the embodiment of the present invention will be described with reference to FIGS.

FIG. 1 shows an unclamped state of the clamp device 1. At this time, the piston 4 of the cylinder 4
c is located at the top dead center of the movable range, and the piston 5c of the cylinder 5 is located at the bottom dead center of the movable range. First, in response to a clamp command from a control device (not shown), the solenoid 13a of the solenoid valve 13 is excited, and the solenoid valve 13 switches to the state shown in FIG.

Then, the air supplied from the air supply source 14 is supplied to the cylinder chamber 5 b of the cylinder 5 through the first port 15.
To the extension side of the piston 5 as shown in FIG.
c is raised to the top dead center of the movable range. Then, the protrusion restriction of the piston 6a by the protruding pipe line 5f is released,
As shown in FIG. 3, the piston rod 6a is pushed out by the coil spring 6d and projects into the sub chamber 5g. The piston rod 6a supports the protruding pipe line 5f from below, and prevents the clamp pin 2 from dropping.

By raising the piston 5c of the cylinder 5,
The air on the contraction side of the cylinder chamber 5b passes through the passage 20, the sub-chamber 5d,
Air is exhausted through the cylinder chamber 4b, the pipe 17, and the second port 16.

When the piston 5c rises, the protruding pipe 5f projecting below the piston 5c is withdrawn from the sub chamber 5g. Then, seal in the unclamped state of FIG.
Air on the extension side of the cylinder chamber 5b flows between the protruding pipe line 5f sealed by 26 and the sub chamber 5g. The inflow air is supplied to the sub chamber 5g, the protruding pipe 5f, the pipe 4e,
Projection pipe 4d, passage 18 formed in piston rod 4a
, Is supplied to the contracted side of the cylinder chamber 4b of the cylinder 4.

The piston 4c is lowered by the air supplied to the compression side of the cylinder chamber 4b. Then, the clamp claw 3 pivotally supported by the piston rod 4a via the pivot shaft is lowered, and the distal end 3a is made to protrude laterally from the opening 2e of the clamp pin 2. Then, as shown in FIG. 3, the shoulder 2b of the crankpin 2 and the clamp pawl 3
The workpiece W is clamped with the tip 3a of the workpiece W.

When the piston 4c descends, the projecting pipe 4d projecting below the piston 4c is fitted into the sub-chamber 5d of the piston 5c which stops at the top dead center. The check valve function of the seal 24 allows the air in the sub chamber 5d to flow through the second port 16 through the pipe 17 on the extension side of the cylinder chamber 4b.
Exhaust from

When the clamp device 1 shown in FIG. 3 is in the clamped state, the piston rod 4a has moved to the bottom dead center. Therefore, the position of the piston rod 4a is detected by the proximity switch 31 and the control device ( (Not shown) to output a clamp completion signal to end the clamp operation.

Next, a procedure for returning from the clamp state of the clamp device 1 shown in FIG. 3 to the unclamped state of FIG. 1 will be described. First, upon receipt of an unclamping command from a control device (not shown), the solenoid 13b of the solenoid valve 13 is received.
Is excited, and the solenoid valve 13 switches from the state shown in FIG. 3 to the state shown in FIG.

Then, the air supplied from the air supply source 14 is supplied to the contracted side of the cylinder chamber 6b through the second port 16 and the passage 19, and the piston 6c resists the urging force of the coil spring 6d. As shown in FIG. 2, the piston rod 6a is in a retracted state, and the prevention of the fall of the clamp pin 2 is released.

At the same time, air is supplied to the extension side of the cylinder chamber 4b of the cylinder 4 via the pipe 17, and the piston 4c moves from the bottom dead center shown in FIG. 3 to the top dead center shown in FIG. And rise. Then, the clamp claw 3 pivotally supported by the piston rod 4a rises and stores the distal end 3a inside the clamp pin 2. Air on the contraction side of the cylinder chamber 4b is exhausted through the passage 18, the protruding pipe 4e, the sub chamber 5g, the extension side of the cylinder chamber 5b, and the first port 15.

By raising the piston 4c of the cylinder 4,
The projecting pipe 4d projecting below the piston 4c is
Removed from d. Then, the air on the extension side of the cylinder chamber 4b flows between the protruding pipe line 4d and the sub-chamber 5d which have been sealed by the seal 24 in the clamped state of FIG. The inflow air is supplied to the cylinder 5 via the sub chamber 5d and the passage 20 to the contracted side of the cylinder chamber 5b.

Therefore, the piston 5c descends from the top dead center shown in FIG. 2 to the bottom dead center shown in FIG. And
The cylinder 4, the clamp claw 3, and the clamp pin 2 riding on the piston 5c also descend, and the clamp pin 2 is separated from the positioning hole Wa of the work W, and enters an unclamped state. At this time, the protruding pipe line 5f protruding below the piston 5c is inserted into the sub chamber 5g, but the air in the sub chamber 5g is forced to extend on the extension side of the cylinder chamber 5b by the check valve function of the seal 26. Air is exhausted from the first port through the first port.

When the clamping device 1 shown in FIG. 1 is in the unclamping state, the position of the piston 5c is detected by the reed switch 32, and an unclamping completion signal is output to a control device (not shown), and the unclamping is performed. Finish the work.

According to the clamp device having the above-described configuration according to the embodiment of the present invention, the following operation and effect can be obtained. When the clamp device 1 according to the embodiment of the present invention operates from the unclamped state (FIG. 1) to the clamped state (FIG. 3), the first port 15 is supplied with air so that the first port 15 is supplied with air. 15-Extension side of cylinder chamber 5b-Subchamber 5g-Protrusion pipe 5f-Pipe 4e-Protrusion pipe 4d-Passage 18-Retraction side of cylinder chamber 4b-Cylinder chamber 4
An air supply circuit is formed to supply air in the order of the contraction side of b.

When operating from the clamp state (FIG. 3) to the unclamped state (FIG. 1), air is supplied to the second port 16 so that the second port 16-passage 19-cylinder 6b An air supply circuit for supplying air in this order, and an air supply circuit in parallel therewith, in the order of the second port 16-pipe 17-extension side of cylinder chamber 4 b-sub-chamber 5 d-passage 20-cylinder chamber 5 b An air supply circuit for supplying air is formed. Such a parallel air supply circuit includes an air supply source 14.
This is a system of air supply circuits that is operated by air supplied from the air.

That is, the clamp device 1 according to the embodiment of the present invention has three systems: raising and lowering the positioning pin 2, opening and closing the clamp claw 3, and expanding and contracting the piston rod 6 a for fixing the positioning pin 2. The three cylinders 4, 5, 6 according to the operation mechanism are arranged in one system of a fluid supply circuit.

Further, when operating from the unclamped state to the clamped state, the two cylinders 4 and 5 are arranged in series with the cylinder 5 and the cylinder 4 in the one system of the fluid supply circuit. The subchamber 5g, the protruding pipe 5f, and the seal 26 constitute a valve structure for opening and closing the fluid supply circuit from the cylinder 5 to the cylinder 4 in accordance with the position of the piston 5c, using only mechanical elements of the cylinder 5. ing.
The sub chamber 5d, the projecting pipe 4d, and the seal 24 constitute a valve structure for opening and closing a fluid supply circuit from the cylinder 4 to the cylinder 5 in accordance with the position of the piston 4c, using only mechanical elements of the cylinder 4. ing.

When operating from the clamp state to the unclamped state, the two cylinders 4 and 5 are arranged in series with the cylinder 4 and the cylinder 5 in the one system of the fluid supply circuit. Then, as described above, the sub-chamber 5d, the protruding pipe line 4d, and the seal 24 are arranged in accordance with the position of the piston 4c.
A valve structure for opening and closing a fluid supply circuit from the cylinder 4 to the cylinder 5 is configured.

That is, the clamp device 1 according to the embodiment of the present invention includes a valve structure that opens and closes a fluid supply circuit to a downstream cylinder in accordance with a piston position of an upstream cylinder. With such a valve structure, the two cylinders 4 and 5 can be operated sequentially.

Therefore, the clamp device 1 according to the embodiment of the present invention requires only one air supply source 14 and one solenoid valve 13 even if the number of cylinders increases due to the multi-system operation mechanism. Only need. Therefore, the cylinder control electric circuit only needs to be provided for the solenoid valve 13. Further, in the control contents, the excitation of the solenoids 13a and 13b of the solenoid valve 13 and the air supply source 1
Since only the operation relating to the operation 4 is performed, the predetermined operation can be performed without complicating the control contents.

The work W is positioned by the operation of the positioning pin 2, the work W positioned by the operation of the clamp claw 3 is fixed, and the positioning pin 2 is dropped by the fall prevention mechanism (piston rod 6a). Thus, accurate positioning and fixing of the work W can be ensured.

In the embodiment of the present invention, only the cylinder 6 is used as a power source in the extension direction,
Although d is provided on the extension side of the cylinder chamber 6b, in the other cylinders 4 and 5, it is also possible to replace the power of one of the outward path and the return path of the piston with a spring force. Further, it is possible to cope with further multi-system of the operation mechanism.

[0053]

As described above, the present invention has the following effects. First, according to the clamp device according to claim 1 of the present invention, in a clamp device in which a multi-system operating mechanism is driven by a plurality of cylinders, complicated electrical control is not performed, and the fluid supply circuit is complicated. It is possible to perform accurate positioning and reliable fixing of the work without causing any trouble.

According to the clamp device of the second aspect of the present invention, the plurality of cylinders can be sequentially operated at a predetermined timing without performing complicated electric control, and a simple structure is achieved. Thus, accurate positioning and fixing of the work can be ensured.

According to a third aspect of the present invention, the work is positioned by the positioning pin, and the work positioned by the positioning pin is fixed by a clamp claw. By fixing the positioning pins, accurate positioning and fixing of the work can be ensured.

According to the clamp device of the fourth aspect of the present invention, the three cylinders of the three-system operating mechanism are operated at a predetermined timing by the fluid supplied from one fluid supply source, and the clamp is operated. The operation can be performed reliably.

According to the clamp device of the fifth aspect of the present invention, the three cylinders of the three-system operating mechanism are operated at a predetermined timing by the fluid supplied from one fluid supply source, and Clamping operation can be performed reliably.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing an unclamped state of a clamp device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view schematically showing an intermediate operation state of the clamp device according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view schematically showing a clamp state of the clamp device according to the embodiment of the present invention.

FIG. 4 is a cross-sectional view schematically showing a conventional clamping device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Clamping device 2 Clamp pin 3 Clamp claw 4 Cylinder 4a Piston rod 4b Cylinder chamber 4c Piston 4d Projected pipe 4e Pipe 5 Cylinder 5a Piston rod 5b Cylinder chamber 5c Piston 5d Sub chamber 5f Projected pipe 5g Sub chamber 6 cylinder 6a Piston rod 6b Cylinder chamber 6c Piston 6d Coil spring 13 Solenoid valve 14 Air supply source 15 1st port 16 2nd port 17 Pipe 18 Passage 19 Passage 20 Passage 24,26 Seal W Work Wa Positioning hole

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akatsuki Takae 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Mikio Hanai 1 Toyota Town, Toyota City, Toyota City Inside Toyota Motor Corporation (72) Inventor Hiroshi Tanaka 2-250, Otonoki, Komaki-shi, Aichi F-term in CK Corporation (reference) 3C016 AA01 CA04 CB03 CE05 HA06 HC02

Claims (5)

[Claims] 1. A clamping device having a multi-system operating mechanism driven by a plurality of cylinders, comprising a single-system fluid supply circuit for sequentially operating the plurality of cylinders at a predetermined timing. A clamping device. 2. A valve structure, wherein said plurality of cylinders are arranged in series in said one system of fluid supply circuit and control a fluid supply amount to a downstream cylinder in accordance with a piston position of an upstream cylinder. 2. The method according to claim 1, wherein
The clamping device as described. 3. The multi-system operating mechanism includes a positioning pin that moves up and down, a clamp claw that fixes a work positioned by the positioning pin, and a mechanism that prevents the positioning pin from falling. 3. The clamp device according to 1 or 2. 4. When in an unclamped state, the pressure fluid supplied to the fluid supply circuit drives a cylinder related to the elevation of the positioning pin to raise the positioning pin. 4. The clamp device according to claim 3, wherein a cylinder for driving the pawl is driven to clamp the work, and a cylinder of the positioning pin falling prevention mechanism is driven to fix the positioning pin. 5. The pressure fluid supplied to the fluid supply circuit when in a clamp state drives a cylinder of a mechanism for preventing the positioning pin from dropping to release the fixing of the positioning pin, and The cylinder for driving a clamp claw is driven to unclamp a workpiece, and then the cylinder related to the elevation of the positioning pin is driven to lower the positioning pin. Clamping device.