JP2000354902A - Work piece holding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the skip of a temporary clamping step between an unclamping step and a regular clamping step due to the malfunction of various valves. SOLUTION: A work piece holding device sets a temporary clamping position between an unclamping position and a regular clamping position, as a piston position of a clamp cylinder actuating a clamp mechanism. A quantitatively distributing cylinder 38 and a bypass switching valve 46 are installed in a parallel before the clamp cylinder 15, and the quantitatively distributing cylinder 38 is actuated in a state that the valve 46 is shut off, which switches the piston to the temporary clamping position. At this time, it is checked, with a pressure switch 48 or the like, whether the bypass switching valve 46 is at a shut off position or not, and if the valve is not at the shut off position, the switching to the temporary position is prohibited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work holding device for holding a work in a machine tool.

[0002]

2. Description of the Related Art In a conventional workpiece gripping device, a temporary clamping position is set as an intermediate stage between an unclamping position for releasing a workpiece and a main clamping position for completely gripping the workpiece. There is known a configuration in which the safety is enhanced more than a configuration in which the unclamping position is immediately switched to the main clamping position. One example is shown in FIGS.
Shown in

In FIG. 1, reference numeral 10 denotes a main shaft of a machine tool. A substantially cylindrical base member 11 is fixed to the end of the main shaft 10, and a substrate 12 is fixed to the end. A thin-walled diaphragm 13 is provided on the further front end side of the substrate 12, and a through-hole 13 a for assisting the deformation of the diaphragm 13 is provided at a central portion thereof. A plurality (three in the illustrated example) of clamp members 14 are fixed to the outer peripheral portion of the diaphragm 13 in a state of being arranged at equal intervals in the circumferential direction, and the distal end of each clamp member 14 has an inwardly protruding claw 1.
4a are formed.

On the other hand, at the center of the main shaft 10, the main shaft 1
A draw bar (operation shaft) 16 that rotates integrally with the zero is inserted therethrough, and an operation member 17 is provided at the tip of the draw bar 16. At the tip of the operation member 17, a pusher 19 for pressing the peripheral portion of the through hole 13a of the diaphragm 13 is protruded. A donut-shaped operation plate 18 is provided around an intermediate portion of the operation member 17, and a central portion thereof has a spherical surface 17 formed on an outer peripheral surface of the operation member 17.
b.

[0005] A rear end of an operation shaft 20 is connected to the operation plate 18 so as to be relatively rotatable. The operating shaft 20 protrudes toward the distal end through the bush 22 and the diaphragm 13 provided on the substrate 12, and a pulling claw 24 is fixed to the protruding distal end. FIG. 1 shows the outer peripheral surface of the operation shaft 20.
2 (b), a cam groove 20a having an inclined portion in the middle
Is formed, and the bush 22 is provided with the cam groove 20a.
A pin 22a that fits into the shaft is fixed, and the operating shaft 20 is rotated by a predetermined angle in conjunction with the axial movement of the operating shaft 20 by a cam mechanism including the pin 22a.

[0006] In FIG. 12A and FIG.
Reference numeral 6 denotes a backing plate. The backing plate 26 is fixed to the substrate 12 via a mounting shaft 28 that penetrates through the diaphragm 13.

The operation of this device is as follows.

1) Unclamp state Before setting the workpiece W, the draw bar 16
The operation member 17 and the operation shaft 20 are advanced integrally. At this time, the pusher 19 of the operation member 17 is
As shown by the two-dot chain line 19a in FIG.
By pressing the portion in the vicinity of the center toward the front end side, the diaphragm 13 is deformed, and the claw 14a fixed to the diaphragm 13 is shown in a two-dot chain line in FIG. 12A and FIG. 14B. The workpiece W is held in the open position to release the workpiece W. The pulling claw 24 is also a two-dot chain line 24a in FIG.
As shown in FIG. 7, the workpiece W is located far away from the holding position of the workpiece W by a large distance. In addition, the angular position is maintained at a retreat angular position that does not interfere with the workpiece W when the workpiece W is set from the front, as shown by the two-dot chain line in FIG.
This state is an unclamped state in which both the holding claws 14a and the pulling claws 24 are sufficiently separated from the workpiece setting position.

2) Temporary clamp In the unclamped state, when an operator presses a temporary clamp command switch (not shown) with the other hand while holding the workpiece W with one hand and applying it to the backing plate 26 from the front,
The draw bar 16, the retracting plate 18, and the rod 20 are retracted integrally by a limited stroke. This allows
The pusher 19 is retracted to the position shown by the two-dot chain line 19b in FIG. 12A, and the diaphragm 13 is released. That is, since the diaphragm 13 returns to the non-deformed state, the holding claws 14a fixed to the diaphragm 13
As shown in FIG. 14A and FIG. 14A, the workpiece W is moved to a holding position for supporting the workpiece W from the side. However, pull nail 2
4 is still kept sufficiently away from the workpiece W as indicated by a two-dot chain line 24b in FIG.
The hand of the worker holding the work piece W
There is no danger of being caught between them. Thus, the claws 1
By placing the temporary clamping stage in which the workpiece W is held only by 4a before the next main clamp, higher safety can be ensured than when the transition to the main clamp is suddenly made.

3) Main clamp In the temporary clamp state, an operator releases his / her hand from the workpiece W,
Next, when the two main clamp command switches are simultaneously operated with both hands, the draw bar 16, the retracting plate 18, and the rod 20 are further moved from the temporary clamp position as shown in FIG.
To the position indicated by the solid line. At this time, the operating shaft 20 and the pulling claw 24 rotate and move backward by the cam action of the cam groove 20a and the pin 22a. As a result, the pulling claw 24 is moved to the retracted position where the work W is sandwiched between the backing plate 26 and the back and forth direction. It moves (FIGS. 12 (a) and 13), whereby the main clamp is achieved. If the main clamp command switch for shifting to the main clamp is configured to be operated only by the operator using both hands, it is possible to prevent the operator's hand from being caught between the workpiece W and the pulling claw 24. It is possible to reliably prevent it.

As described above, in the workpiece gripping device in which the temporary clamping position is set between the unclamping position and the main clamping position, a drive system for positioning the draw bar 16 at three positions is required. One example of a hydraulic circuit as a specific means is shown in FIGS.

In FIG. 1, reference numeral 15 denotes a clamp cylinder comprising a hydraulic cylinder, and its telescopic rod is configured as the draw bar 16 as it is. The inside of the clamp cylinder 15 is divided into a head-side chamber (first working chamber) 15h and a rod-side chamber (second working chamber) 15r by a piston connected to the draw bar 16.

This circuit includes a hydraulic pump 30, a main switching valve 32, and a fixed distribution cylinder 38 in addition to the clamp cylinder 15.

The fixed quantity distributing cylinder 38 is composed of a hydraulic cylinder like the clamp cylinder 15, and its interior is partitioned into a head side chamber (first working chamber) 38h and a rod side chamber (second working chamber) 38r. ing. However, the whole capacity is smaller than that of the clamp cylinder 15, and only the flow of oil from the head side chamber 38h to the rod side chamber 38r is allowed in the piston (that is, from the rod side chamber 38r to the head side chamber 38h). The check valve 40 is provided. The head side chamber 38h is directly connected to the rod side chamber 16 of the clamp cylinder 15, while a stroke detection switch 42 for detecting the stroke position is provided near the telescopic rod.

The main switching valve 32 is a two-position electromagnetic switching valve whose position is switched by excitation of a solenoid, and has an A port and a B port as its output ports. A
The port is the head side chamber 15h of the clamp cylinder 15.
And the B port is connected to the rod side chamber 38r of the fixed quantity distribution cylinder 38. When one of the solenoids of the main switching valve 32 is excited, FIG.
When the A port is connected to the discharge side of the hydraulic pump 30 and the B port is switched to the first switching position to connect to the tank as shown in FIG.
As shown in FIG. 16, the port A is connected to the tank, and the port B is switched to a second switching position where the port B is connected to the discharge side of the hydraulic pump 30.

Further, in this circuit, a bypass passage 34 is provided between the B port and the rod side chamber 15r of the clamp cylinder 15 to bypass the fixed quantity distribution cylinder 38, and a bypass switching valve 36 is provided in the middle thereof. ing. This bypass switching valve 36 is also a two-position solenoid switching valve, similar to the main switching valve 32, and shuts off the bypass passage 34 as shown in FIGS. 15 and 16 when the solenoid provided on one side thereof is not excited. Is switched to the shut-off position, and the solenoid is excited, as shown in FIG.
As shown in FIG. 18, the position can be switched to a communication position for communicating with the bypass passage 34.

The operation of this circuit is as follows.

1) Unclamped state (FIG. 15) In the initial unclamped state, the head side chamber 15h of the clamp cylinder 15 and the head side chamber 38h of the fixed quantity distribution cylinder 38 are each set to the maximum capacity. The operating member 17 at the distal end of the draw bar 16 which is a telescopic rod is in the unclamping position (the position where the pusher 19 presses the diaphragm 13 as shown by the two-dot chain line 19a in FIG. 12A). Is held. The main switching valve 32 is switched to the first switching position, and the bypass switching valve 36 is switched to the shutoff position.

2) Temporary Clamp (FIG. 16) When the temporary clamp command switch is input from the unclamped state, the main switching valve 32 is switched to the second switching position. Thereby, the head side chamber 15h of the clamp cylinder 15 is communicated with the tank through the A port,
The discharge oil (pressure fluid) of the hydraulic pump 30 is supplied to the rod side chamber 38r of the fixed quantity distribution cylinder 38 through the B port. As a result, the rod of the fixed quantity distribution cylinder 38 contracts, and the oil in the head side chamber 38h is transferred to the rod side chamber 15r of the clamp cylinder 15 by the stroke.
As a result, the clamp cylinder 15 contracts by a limited stroke, and the draw bar 16 and the operation member 17 are positioned at the temporary clamp position, which is an intermediate position.

3) Main Clamp (FIG. 17) When the main clamp command switch is input from the temporary clamp state, the solenoid of the bypass switching valve 36 is excited, and the switching valve 36 is switched to the communication position. As a result, the discharge oil of the hydraulic pump 30 flows through the B port and the bypass passage 34 through the rod side chamber 15 of the clamp cylinder 15.
r directly. Thereby, the clamp cylinder 1
5 is fully contracted, and the draw bar 16 and the operation member 17 are fully retracted to the full clamp position.

4) Return to the unclamped state When a clamp release command is input in the main clamped state, first, the bypass switching valve 36 is returned to the shut-off position, and then the main switching valve 32 is returned to the first switching position. . As a result, the discharge oil of the hydraulic pump 30 is supplied to the head side chamber 15h of the clamp cylinder 15, the cylinder 15 extends to the unclamping position, and is pushed out from the rod side chamber 15r of the cylinder 15 with the extension. When the oil is supplied to the head side chamber 38h of the fixed amount distributing cylinder 38, the identified amount distributing cylinder 38 is also extended, and finally, as shown in FIG.
The state returns to the unclamped state 5. At this time, the oil corresponding to the difference between the capacity of the clamp cylinder 15 and the capacity of the fixed amount distribution cylinder 38 is supplied from the head side chamber 38h of the identified amount distribution cylinder 38 to the rod side chamber 38r through the check valve 40 in the piston. Escaped to the tank.

[0022]

The driving circuits shown in FIGS. 15 to 18 have the following problems to be solved.

A) When a foreign matter such as cutting chips gets into the check valve 40 provided in the piston of the fixed quantity distribution cylinder 38 and the check valve 40 loses the check function, the check valve is switched from the unclamped state of FIG. Main switching valve 3 to switch to temporary clamp state
2 is switched to the second switching position (that is, the position where the discharge oil is supplied to the rod side chamber 38r of the fixed quantity distribution cylinder 38), the pressure oil in the rod side chamber 38r of the cylinder 38 is discharged from the check valve 40 to the head. Leakage into the side chamber 38h may cause the clamp cylinder 15 to pass through the temporary clamp position shown in FIG. 16 and reach the main clamp position immediately.

B) In the main clamping state shown in FIG. 17, if a switching failure occurs in the switching valve 36 due to foreign matter such as cutting chips getting stuck in the spool of the bypass switching valve 36, the state of the main clamping state shown in FIG. There is a case where the switching valve 36 does not return from the communicating position to the shut-off position even if the excitation of the solenoid of the bypass switching valve 36 is canceled in order to shift to the state of FIG. In this case, the clamp cylinder 15 is returned to the unclamping position by returning the main switching valve 32 to the first switching position, but then the main switching valve 32 is again switched to the second switching position in order to switch to the temporary clamping state. When switching to
Since the bypass switching valve 36 remains in the communication position,
The discharge oil of the hydraulic pump 30 is directly supplied to the rod-side chamber 15r of the clamp cylinder 15 through the bypass passage 34, whereby there is a possibility that the hydraulic fluid will pass through the temporary clamp state and immediately switch to the main clamp state. In addition, since the operation failure of the bypass switching valve 36 cannot be confirmed from outside, the user cannot predict the sudden switching from the unclamped state to the main clamped state.

The above description relates to a device which is switched in the order of unclamping → temporary clamping → final clamping. Conversely, a device in which the temporary clamping stage is set during the return from the main clamping state to the unclamping state ( For example, in a device in which a temporary clamping stage is set in the middle to prevent the workpiece W from suddenly being released from the main clamping state and falling, the temporary clamping stage is skipped according to the same principle as described above. There is a risk that it will.

In view of such circumstances, the present invention switches from the unclamped state to the fully clamped state by the temporary clamping stage disappearing due to the malfunction of various valves, or from the fully clamped state to the unclamped state. It is an object of the present invention to provide a workpiece gripping device capable of preventing the inconvenience of suddenly switching to the workpiece.

[0027]

As a means for solving the above problems, the present invention provides a clamp mechanism for gripping a workpiece, and first and second working chambers formed on both sides of a piston. The clamp mechanism is switched between an unclamped state and a clamped state by the operation of the piston of the clamp cylinder, and the piston is switched as a piston switching position of the clamp cylinder. ,
In a workpiece gripping device in which a temporary clamping position is set between an unclamping position and a main clamping position, the workpiece gripping device includes a fixed quantity distributing cylinder having a smaller capacity than the clamp cylinder, and a first operation formed on both sides of the piston. A first working chamber of the chamber and the second working chamber is connected to a second working chamber of the clamp cylinder, a pressurized fluid is supplied to the first working chamber of the clamp cylinder, and a second operation of the fixed quantity distributing cylinder is performed. A main switching valve capable of switching between a first switching position for releasing fluid in the chamber and a second switching position for supplying pressure fluid to the second working chamber of the fixed quantity distributing cylinder and releasing fluid in the first working chamber of the clamp cylinder. And a second of the main switching valve and the clamp cylinder.
A bypass switching valve that is provided in a bypass passage that bypasses the fixed quantity distribution cylinder between the working chamber and the fixed quantity distribution cylinder, and is provided with a bypass switching valve that is switched between a communication position that communicates with the bypass passage and a cutoff position that shuts off the fixed quantity distribution cylinder; A configuration in which the piston of the clamp cylinder is switched to the temporary clamp position in a state where the fluid is transferred to the second working chamber of the clamp cylinder by an amount, and whether or not the bypass switching valve is in the shut-off position. And a switching prohibiting means for prohibiting switching of the main switching valve from the first switching position to the second switching position when the bypass switching valve is not in the shut-off position. .

In this device, the bypass switching valve is switched to the shut-off position in a state in which the second working chamber of the clamp cylinder and the second working chamber of the fixed quantity distributing cylinder are each at the minimum capacity (unclamped state or main clamped state). Further, by switching the main switching valve to the second switching position, the pressure fluid is supplied to the second working chamber of the fixed quantity distributing cylinder, and the identified amount distributing cylinder strokes, and the stroke is moved by the stroke to the second working chamber of the clamp cylinder. By supplying the hydraulic oil, the piston of the clamp cylinder is switched to the intermediate temporary clamp position. Thereafter, the bypass switching valve is switched to the communication position, and the pressurized fluid is directly supplied to the second working chamber of the clamp cylinder through the bypass switching valve. The state is switched to the clamp state.

Here, when the bypass switching valve cannot be switched to the shut-off position due to a malfunction thereof, that is, when it cannot be switched from the communication position, the main switching valve is switched to the first switching state in that state. When switching from the position to the second switching position, the pressure fluid is suddenly supplied to the second working chamber of the clamp cylinder through the bypass switching valve, and the clamp cylinder passes through the temporary clamping position and makes a full stroke. However, in the device according to the present invention, it is previously confirmed whether or not the bypass switching valve is at the shut-off position, and when the switching valve is at the communication position, the operation of switching the main switching valve to the second switching position (ie, (Temporary clamp transfer operation) is prohibited. There is no possibility to be switched to (unclamped state or from the clamped state) state. Thereby, high security is ensured.

Here, as the bypass detecting means for detecting whether or not the bypass switching valve is in the shut-off position, a sensor for directly detecting the spool stroke of the bypass switching valve may be incorporated in the switching valve. Preferably, the bypass switching valve is configured to release a part of the pressure fluid supplied from the main switching valve to the first working chamber of the clamp cylinder to a specific relief path only in a state where the bypass switching valve is switched to the shutoff position. In addition, if a fluid detecting means for detecting whether or not fluid is flowing in the relief path is provided, the switching state of the bypass switching valve can be confirmed with a simple and inexpensive configuration.

In addition to the above-mentioned switching prohibition,
If a warning control means for outputting a warning signal when the bypass switching valve is not in the shut-off position when a command for switching the main switching valve from the first switching position to the second switching position is input, The failure of the circuit can be clearly notified.

The present invention also provides a clamp mechanism for gripping a workpiece, a clamp cylinder for operating the piston by supplying a working fluid to first and second working chambers formed on both sides of the piston. The clamp mechanism is switched between an unclamped state and a clamped state by actuation of a piston of the clamp cylinder, and a temporary clamp position is provided between the unclamped position and the main clamp position as a piston switching position of the clamp cylinder. Is provided with a fixed quantity distributing cylinder having a smaller capacity than the clamp cylinder, and the first working chamber among the first working chamber and the second working chamber formed on both sides of the piston is provided. A first operation of the clamp cylinder is connected to a second operation chamber of the clamp cylinder. The escape of the second working chamber of fluid in the dosing cylinder supplies pressure fluid to the 1
A main switching valve switchable between a switching position and a second switching position for supplying pressure fluid to the second working chamber of the fixed quantity distributing cylinder and releasing fluid in the first working chamber of the clamp cylinder; A bypass switching valve provided in a bypass passage that bypasses the fixed quantity distribution cylinder between the second working chamber of the clamp cylinder and a communication position that communicates with the bypass passage and a shutoff position that shuts off the communication; The piston of the clamp cylinder is switched to the temporary clamping position in a state where the fluid is transferred into the second working chamber of the clamp cylinder by the stroke of the fixed-quantity distribution cylinder, and the stroke of the fixed-quantity distribution cylinder A stroke position detecting means for detecting a position, wherein the main switching valve is switched to a second switching position; When returning the pistons of both the clamp cylinder and the quantitative distribution cylinder to the reverse position from the state where the bypass switching valve has been switched to the communication position, first the bypass switching valve is switched to the shut-off position, and then the main switching valve is switched to the first switching position. And a switching control means for switching the bypass switching valve to the communication position after the stroke position detecting means detects that the fixed quantity distribution cylinder has returned to the reverse position by this switching.

According to this configuration, the pistons of both the clamp cylinder and the fixed-quantity distribution cylinder are returned to the reverse positions from the state where the main switching valve is switched to the second switching position and the bypass switching valve is switched to the communication position. At the time, that is, when returning from the main clamp state to the unclamped state or when returning from the unclamped state to the main clamp state, the switching control using the stroke position detecting means of the fixed quantity distribution cylinder is performed, so that The piston position of each cylinder can be switched without providing a check valve on the piston of the distribution cylinder, thereby preventing the problem that the temporary clamping position is skipped due to the malfunction of the check valve. be able to.

According to the present invention, there is provided a clamp mechanism for gripping a workpiece, a clamp cylinder for operating the piston by supplying a working fluid to a first working chamber and a second working chamber formed on both sides of the piston. The clamp mechanism is switched between an unclamped state and a clamped state by actuation of a piston of the clamp cylinder, and a temporary clamp position is provided between the unclamped position and the main clamp position as a piston switching position of the clamp cylinder. Is provided with a fixed quantity distributing cylinder having a smaller capacity than the clamp cylinder, and the first working chamber among the first working chamber and the second working chamber formed on both sides of the piston is provided. A first operation of the clamp cylinder is connected to a second operation chamber of the clamp cylinder. The escape of the second working chamber of fluid in the dosing cylinder supplies pressure fluid to the 1
A main switching valve switchable between a switching position and a second switching position for supplying pressure fluid to the second working chamber of the fixed quantity distributing cylinder and releasing fluid in the first working chamber of the clamp cylinder; A bypass switching valve provided in a bypass passage that bypasses the fixed quantity distribution cylinder between the second working chamber of the clamp cylinder and a communication position that communicates with the bypass passage and a shutoff position that shuts off the communication; The piston of the clamp cylinder is configured to be switched to the temporary clamp position in a state where the fluid is transferred into the second working chamber of the clamp cylinder by the stroke of the fixed amount distribution cylinder, and in the middle of the bypass passage. An aperture is provided.

According to this configuration, the pistons of both the clamp cylinder and the fixed-quantity distribution cylinder are returned to the reverse positions from the state where the main switching valve is switched to the second switching position and the bypass switching valve is switched to the communication position. In such a case, it is only necessary to perform an operation for switching the main switching valve from the second switching position to the first switching position while the bypass switching valve is in the communication state. By this operation, the pressurized fluid is supplied to the first working chamber of the clamp cylinder and the clamp cylinder strokes, and the fluid in the second working chamber is pushed out to the fixed quantity distribution cylinder side and the bypass passage side. Is provided with a throttle and has a high flow resistance, so that the fluid flows preferentially to the metering cylinder side, so that the piston of the metering cylinder first returns to its original position. Thereafter, the oil in the second working chamber of the clamp cylinder is released through the throttle, and the piston of the clamp cylinder also completely returns to its original position.

Therefore, according to this apparatus, it is possible to return the piston positions of both the clamp cylinder and the fixed quantity distributing cylinder without providing a check valve on the piston of the fixed quantity distributing cylinder unlike the conventional apparatus. The inconvenience that the temporary clamping stage is skipped due to the malfunction of the stop valve can be reliably prevented.

In this apparatus, it is more preferable that a check valve is provided in parallel with the throttle to prevent the flow of fluid in the direction only from the second working chamber of the clamp cylinder to the main switching valve. According to this configuration, when the main switching valve is switched from the first switching position to the second switching position in order to shift from the temporary clamp state to the main clamp state or the unclamped state, the pressure fluid passes through the check valve (ie, Since the pressure fluid is supplied to the second working chamber of the clamp cylinder (bypassing the throttle), the same pressure fluid flows through the throttle to the second working chamber.
The switching from the temporary clamp state to the main clamp state or the unclamped state is performed more quickly than when supplied to the working chamber.

In the apparatus provided with the throttle and the stroke position detecting means and the switching control means, furthermore, a bypass detecting means for detecting whether or not the bypass switching valve is at a shut-off position, In the case where the main switching valve is not provided, the switchover inhibiting means for inhibiting the switching of the main switching valve from the first switching position to the second switching position is provided, so that the safety is further enhanced. Also in this case, the bypass switching valve is configured to release a part of the pressure fluid supplied to the first working chamber of the clamp cylinder from the main switching valve to the relief path only when the bypass switching valve is switched to the shutoff position. A fluid detecting means for detecting whether or not fluid is flowing through the relief path; and a bypass switching valve when a command for switching the main switching valve from the first switching position to the second switching position is input. It is needless to say that it is more preferable to provide a warning control means for outputting a warning signal when is not in the shut-off position.

[0039]

Embodiments of the present invention will be described with reference to the drawings. The hardware configuration of the device is the same as that shown in FIGS.
This is the same as that shown in FIG. 14, and the description thereof is omitted here. The basic components of the hydraulic circuit are also the same as those shown in FIGS.
Components that are the same as the components of the circuit shown in the figure are given the same reference numerals, and descriptions thereof will be omitted.

First Embodiment (FIGS. 1 to 6) The apparatus shown here comprises a clamp cylinder 15, a hydraulic pump 30, a main switching valve 32, a fixed distribution cylinder 38, and a bypass switching valve 46. 15 and 18 are common to the conventional devices shown in FIGS. 15 to 18, but the bypass switching valve 46 is a bypass switching valve 3 shown in FIG.
Unlike the sixth embodiment, at the shutoff position, the A port of the main switching valve 32 is configured to escape to the tank side. And
A throttle 44 is provided in the middle of this escape path,
A pressure switch 48 is provided on the upstream side of the throttle 44, and when the pressure on the upstream side of the throttle 44 becomes a certain value or more,
That is, when the discharge oil of the hydraulic pump 30 flows in the relief path, the pressure switch 48 is switched from off to on.

In this apparatus, the check valve is not provided on the piston of the fixed quantity distribution cylinder 38. Instead, the detection signal of the pressure switch 48 and the quantitative distribution cylinder 3
8 and a detection signal of the stroke detection switch 42 are input to a controller 50 composed of a microcomputer or the like.
Special switching control is performed.

Next, the contents of the switching control will be described.

1) Unclamped state (FIG. 1) In the initial unclamped state, the head-side chamber 15h of the clamp cylinder 15 and the head-side chamber 38h of the fixed quantity distribution cylinder 38 are each set to the maximum capacity. The operating member 17 at the distal end of the draw bar 16 which is a telescopic rod is in the unclamping position (the position where the pusher 19 presses the diaphragm 13 as shown by the two-dot chain line 19a in FIG. 12A). Is held. In addition, the main switching valve 32 is switched to the first switching position and the bypass switching valve 46 is switched to the shut-off position unless there is a failure.

2) Temporary Clamp (FIG. 2) When the temporary clamp command switch is input from the unclamped state, the main switching valve 32 is basically set to the second position in FIG.
Before switching to the switching position, the controller 50 first checks whether the pressure switch 48 is on. When the pressure switch 48 is off, that is, when the discharge oil of the hydraulic pump 30 is not flowing to the throttle 44 downstream of the bypass switching valve 46, the bypass switching valve 46 has a switching failure for some reason and is shut off. When the main switching valve 32 is switched to the second switching position in this state, the pump discharge oil is directly supplied to the head side chamber 15h of the clamp cylinder 15 through the bypass switching valve 46. Is supplied, and an erroneous operation that is immediately switched to the main clamping position occurs. To avoid this,
When the pressure switch 48 is off, the controller 50 does not switch the main switching valve 32 (ie, prohibits the switching), and outputs a warning command signal to a suitable warning generating device such as a lamp or a buzzer. I do.

When the pressure switch 48 is on,
Since it can be determined that the bypass switching valve 46 has been normally switched to the shut-off position, the main switching valve 32 is switched to the second switching position in accordance with the input of the temporary clamp command as in the conventional device. Thus, the head side chamber 15h of the clamp cylinder 15 is connected to the tank through the port A, and the discharge oil (pressure fluid) of the hydraulic pump 30 is supplied to the rod side chamber 38r of the fixed quantity distribution cylinder 38 through the port B. As a result, the rod of the fixed quantity distribution cylinder 38 contracts, and the oil in the head side chamber 38h is transferred to the rod side chamber 15r of the clamp cylinder 15 by the stroke.
As a result, the clamp cylinder 15 contracts by a limited stroke, and the draw bar 16 and the operation member 17 are positioned at the temporary clamp position, which is an intermediate position.

3) Main Clamp (FIG. 3) When the main clamp command switch is input from the temporary clamp state, the controller 50 excites the solenoid of the bypass switching valve 46 to bring the switching valve 46 into the communication position shown in FIG. Switch to. As a result, the discharge oil of the hydraulic pump 30 flows through the B port and the bypass passage 34 through the clamp cylinder 1.
5 is directly supplied to the rod side chamber 15r. This allows
The clamp cylinder 15 contracts to the maximum and the draw bar 16
And the operation member 17 is fully retracted to the main clamp position. This operation is exactly the same as the conventional one.

4) Return to the unclamped state (FIGS. 4 to 6) When a clamp release command is input in the main clamp state, the controller 50 moves the clamp cylinder 15 and the fixed quantity distribution cylinder 38 to the positions shown in FIG. The switching control for returning is performed.

Specifically, from the main clamping state shown in FIG. 3, the bypass switching valve 46 is first switched to the shut-off position in FIG. 4, and then the main switching valve 32 is switched to the first switching position shown in FIG. return. As a result, the discharge oil of the hydraulic pump 30 is supplied to the head side chamber 15h of the clamp cylinder 15, and the cylinder 15 extends to the unclamping side, and is extruded from the rod side chamber 15r of the cylinder 15 with the extension. When the oil is supplied to the head side chamber 38h of the fixed quantity distribution cylinder 38, the cylinder 38 also extends. However, unlike the conventional device, the piston of the fixed quantity distributing cylinder 38 is not provided with a check valve, so that the clamp cylinder 1
Only oil corresponding to the stroke of the fixed quantity distribution cylinder 38 can flow from the rod side chamber 15r of No. 5 into the fixed quantity distribution cylinder 38 head side chamber 38h. That is, a part of the oil filled in the rod side chamber 15r stays in the same chamber 15r without any escape place, and as a result, the clamp cylinder 15 stops at the intermediate position (FIG. 5) before the unclamping position. .

Therefore, the controller 50 keeps the main switching valve 32 at the first switching position when the stroke detection switch 42 detects that the fixed quantity distribution cylinder 38 has been fully extended by switching the main switching valve 32. The bypass switching valve 46 is switched to the communication position in FIG. This allows the oil in the rod side chamber 15r of the clamp cylinder 15 to escape to the tank through the bypass switching valve 46 and the main switching valve 32. As a result, the clamp cylinder 15 reaches the unclamping position shown in FIG. . After that, by switching the bypass switching valve 46 to the shut-off position, the state shown in FIG. 1 can be restored.

As described above, in the apparatus according to the present embodiment, when shifting from the unclamped state in FIG. 1 to the temporary clamping position in FIG.
It is confirmed whether or not the bypass switching valve 46 is in the shut-off position by the signal of (1), and only when it is in the shut-off position, the switching operation to the temporary clamp, that is, the operation of switching the main switching valve 32 to the second switching position is performed. Since the main switching valve 32 is switched to the second switching position while the bypass switching valve 46 is in the communication position due to the failure, the inconvenience of suddenly switching from the unclamped state to the main clamped state is reliably prevented. can do.

In this apparatus, when returning from the main clamping state to the unclamping state, the switching control based on the detection signal of the stroke detection switch 42 as shown in FIGS. 38
This eliminates the need to provide a check valve on the piston, thereby preventing the inconvenience of suddenly switching from the unclamped state to the actual clamped state due to malfunction of the check valve. I have.

Second Embodiment (FIGS. 7 to 10) The basic structure of an apparatus according to the second embodiment is the same as that shown in the first embodiment, but its features are described below. A throttle 52 is provided in the bypass passage 34 in series with the bypass switching valve 46, and a check valve 54 is provided in parallel with the throttle 52. This check valve 54 prevents the flow of oil from the rod side chamber 15r to the B port of the main switching valve 32 in the passage bypassing the throttle 52 (that is, from the B port to the rod side chamber 15).
r is allowed to flow).

In this apparatus, the switching operation from the unclamped state (FIG. 7) to the temporary clamped state (FIG. 8) is exactly the same as that shown in the first embodiment.

When this clamp command switch is inputted from the temporary clamp state, the controller 50 excites the solenoid of the bypass switching valve 46 to switch the switching valve 46 to the communicating position in FIG. Thereby, the discharge oil of the hydraulic pump 30 is supplied to the bypass passage 34 through the B port.
Although a throttle 52 is provided in the bypass passage 34, a check valve 54 is provided in parallel with the throttle 52, and the check valve 54 allows the oil flow to the clamp cylinder 15 side. The discharge oil of the hydraulic pump 30 is directly supplied to the rod side chamber 15r. This allows
The clamp cylinder 15 contracts to the maximum and the draw bar 16
And the operation member 17 is fully retracted to the main clamp position.

Next, when a clamp release command is input in the main clamping state, the controller 50 returns the main switching valve 32 to the first switching position while keeping the bypass switching valve 46 at the communication position. Thereby, the clamp cylinder 15
The discharge oil of the hydraulic pump 30 is supplied to the head side chamber 15h, and the cylinder 15 extends to the unclamping side. With the extension, the oil extruded from the rod side chamber 15r of the cylinder 15 is supplied to the fixed quantity distribution cylinder 38. And flows into both the bypass passage 34. Here, a throttle 52 is provided in the middle of the bypass passage 34, and the throttle 52
The check valve 54 provided in parallel with the main switching valve 32
Since the flow of oil toward the bypass passage 34 is blocked, the flow resistance of the throttle 52 acts on the bypass passage 34 side, and as a result, the oil flowing out from the rod side chamber 15r of the clamp cylinder 15 is moved to the head side chamber 38h side of the fixed quantity distribution cylinder 38. Will flow first. Therefore, the identified amount distribution cylinder 38 is reliably extended. After the cylinder 38 is extended, the oil in the rod side chamber 15r of the clamp cylinder 15 can escape to the tank side through the throttle 52, so that the clamp cylinder 15 also completely extends to the original unclamping position. (The state of FIG. 10).

In the apparatus according to this embodiment,
Without providing a check valve on the piston of the fixed quantity distributing cylinder 38 unlike the conventional apparatus, the two cylinders 15 and
38 can be returned to the initial position shown in FIG. In addition, the two cylinders 15, 15 can be operated by a single operation of returning the main switching valve 32 to the first switching position from the main clamping state shown in FIG.
38 can be returned, and the switching control becomes simpler than in the device according to the first embodiment.

Here, the check valve 54 provided in parallel with the throttle 52 has a check function due to foreign matter being caught in the same manner as the check valve 40 in the conventional apparatus shown in FIGS. Although there is a possibility that the flow resistance will decrease, when the oil leaks from this check valve 54 to some extent, its flow resistance is sufficiently large as compared with the flow resistance on the fixed quantity distribution cylinder 38 side.
There is no possibility that 2 will not work. That is, when returning to the unclamped state from the main clamped state shown in FIG. 9, even if the check function of the check valve 54 is slightly reduced, the oil in the rod side chamber 15 r of the clamp cylinder 15 The normal operation is performed instead of the flow preferentially to the head-side chamber 38h. Also, the leakage of the check valve 54 is very large,
Even if sufficient oil does not flow into the head side chamber 38h and the fixed-quantity distribution cylinder 38 cannot be extended sufficiently, the abnormality can be detected by the stroke detection sensor 42.

Note that the embodiment of the present invention is not limited to the above-described embodiment, and for example, the following embodiment is also possible.

(1) In the above embodiment, the temporary clamp stage is set during the transition from the unclamped state to the main clamp state. However, the temporary clamp stage is set during the return from the main clamp state to the unclamped state. The present invention can also be applied to a device that sets a clamping stage. By setting the temporary clamping stage during the return as described above, it is possible to prevent a situation in which the fully clamped workpiece is suddenly released and falls, and the workpiece is reliably taken out of the gripping device in the temporary clamping stage. Becomes possible.

To achieve such a configuration, as shown in FIG. 11 as a third embodiment, the B of the main switching valve 32
The rod side chamber 15r of the clamp cylinder 15 may be directly connected to the port, and the fixed quantity distribution cylinder 38, the bypass passage 34, and the bypass switching valve 46 may be interposed between the port A and the head side chamber 15h in parallel. In this case, the position where the B port of the main switching valve 32 communicates with the discharge side of the hydraulic pump 30 is the first switching position, and the position where the A port of the main switching valve 32 communicates with the discharge side of the hydraulic pump 30 is the second switching position. And the rod side chamber 15r of the clamp cylinder 15
Corresponds to the first working chamber, and the head side chamber 15h corresponds to the second working chamber. Further, it goes without saying that the throttle 52 and the check valve 54 shown in FIGS. 7 to 10 may be further provided in the apparatus shown in FIG.

(2) FIGS. 12 to 14 show a specific hardware configuration in which both the claws and the pulling claws are provided. However, in the present invention, the clamp mechanism is a single type. However, the present invention can be widely applied to those in which the two-stage switching including the temporary clamping position is performed.

(3) A stroke detection sensor may be directly incorporated in the bypass switching valve 46 as means for confirming and detecting whether or not the bypass switching valve 46 is at the shut-off position. However, as shown in FIG. 1, the bypass switching valve 46 is configured to release the oil discharged from the hydraulic pump 30 in the shut-off position, and a pressure switch determines whether or not oil is flowing in the release path. If the detection is made at 48 or the like, the switching state of the bypass switching valve 46 can be confirmed with a simple and inexpensive configuration.

(4) When a throttle 52 is provided in the middle of the bypass passage 34 as shown in FIGS. 7 to 10, the throttle 52 may be disposed between the bypass switching valve 46 and the main switching valve 32. Good, or depending on the configuration, the bypass switching valve 4
6 can also be formed.

(5) In the above embodiment, oil is used as the working fluid. However, air pressure may be used for those having a relatively low required gripping force.

[0065]

As described above, according to the present invention, switching from the unclamped state to the main clamped state or from the main clamped state to the unclamped state due to malfunction of the bypass switching valve and other valves. Is prevented from suddenly jumping over the temporary clamping stage, thereby improving the safety of the apparatus.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram showing an unclamped state of a workpiece holding device according to a first embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram showing a temporary clamping state of the workpiece holding device according to the first embodiment of the present invention.

FIG. 3 is a hydraulic circuit diagram illustrating a main clamping state of the workpiece holding device according to the first embodiment of the present invention.

FIG. 4 is a hydraulic circuit diagram showing a process of returning the workpiece gripping device from the main clamped state to the unclamped state according to the first embodiment of the present invention.

FIG. 5 is a hydraulic circuit diagram showing a process of returning the workpiece holding device from the main clamp state to the unclamped state according to the first embodiment of the present invention.

FIG. 6 is a hydraulic circuit diagram showing a process of returning the workpiece holding device from the main clamp state to the unclamped state according to the first embodiment of the present invention.

FIG. 7 is a hydraulic circuit diagram showing an unclamped state of the workpiece holding device according to the second embodiment of the present invention.

FIG. 8 is a hydraulic circuit diagram showing a temporary clamping state of the workpiece holding device according to the second embodiment of the present invention.

FIG. 9 is a hydraulic circuit diagram showing a main clamping state of the workpiece holding device according to the second embodiment of the present invention.

FIG. 10 is a hydraulic circuit diagram showing a process of returning the workpiece gripping device from the main clamp state to the unclamped state according to the second embodiment of the present invention.

FIG. 11 is a hydraulic circuit diagram showing a main clamping state of the workpiece holding device according to the third embodiment of the present invention.

12A is a cross-sectional side view illustrating an example of a hardware configuration of a workpiece holding device, and FIG. 12B is a partial cross-sectional plan view illustrating a shape of a cam groove provided on an operation shaft of FIG. is there.

FIG. 13 is a front view of the workpiece holding device according to FIG. 12;

14A is a cross-sectional side view schematically illustrating a state in which the holding claws of the workpiece gripping device according to FIG. 12 are in the holding position; FIG.
(b) is a sectional side view schematically showing a state in which the holding claws are at a release position.

FIG. 15 is a hydraulic circuit diagram showing an unclamped state of a conventional workpiece holding device.

FIG. 16 is a hydraulic circuit diagram showing a temporary clamping state of a conventional workpiece holding device.

FIG. 17 is a hydraulic circuit diagram showing a full clamping state of a conventional workpiece holding device.

FIG. 18 is a hydraulic circuit diagram showing a process of returning the conventional workpiece gripping device from the main clamp state to the unclamped state.

[Explanation of symbols]

13 Diaphragm (constituting a clamp mechanism) 14a Clamping pawl (constituting a clamp mechanism) 15 Clamp cylinder 15h Head side chamber (first working chamber or second working chamber of clamp cylinder) 15r Rod side chamber (second working chamber of clamp cylinder) Or the first working chamber) 24 Pulling claw (constituting a clamp mechanism) 30 Hydraulic pump 32 Main switching valve 34 Bypass passage 38 Quantitative distribution cylinder 38h (First working chamber of quantitative distribution cylinder) 38r (Second working chamber of quantitative distribution cylinder) 42) stroke detection switch 44 throttle (constituting fluid detection means) 46 bypass switching valve 48 pressure switch (constituting fluid detection means) 50 controller (switch inhibition means, switching control means, warning control means)

Claims (9)

[Claims] A clamp mechanism for gripping a workpiece, and a clamp cylinder for operating the piston by supplying a working fluid to a first working chamber and a second working chamber formed on both sides of the piston; The clamp mechanism is switched between the unclamped state and the clamped state by the operation of the piston of the clamp cylinder, and a temporary clamp position is set between the unclamped position and the main clamp position as the piston switched position of the clamp cylinder. In the workpiece gripping device, comprising a fixed amount dispensing cylinder having a smaller capacity than the clamp cylinder,
The first working chamber of the first working chamber and the second working chamber formed on both sides of the piston is connected to the second working chamber of the clamp cylinder.
A first switching position, connected to a working chamber, for supplying a pressurized fluid to a first working chamber of the clamp cylinder and for allowing fluid in a second working chamber of the fixed quantity distributing cylinder to escape, and for a second working chamber of the fixed quantity distributing cylinder. A main switching valve capable of switching to a second switching position for supplying a pressure fluid and releasing a fluid in a first working chamber of the clamp cylinder; and a main switching valve between the main switching valve and the second working chamber of the clamp cylinder. A bypass switching valve that is provided in a bypass passage that bypasses the quantitative distribution cylinder and that is switched between a communication position that communicates with the bypass passage and a blocking position that blocks the bypass passage; 2 With the fluid transferred to the working chamber, the piston of the clamp cylinder is switched to the temporary clamp position. And a bypass detecting means for detecting whether or not the bypass switching valve is at the shut-off position, and, when the bypass switching valve is not at the shut-off position, moving the main switching valve from the first switching position to the second switching position. A workpiece gripping device comprising: a switching prohibition unit that prohibits switching to a switching position. 2. The work gripping device according to claim 1, wherein the pressurized fluid supplied from the main switching valve to the first working chamber of the clamp cylinder only when the bypass switching valve is switched to the shut-off position. A part of the work is released to a specific relief path, and fluid detection means for detecting whether or not fluid is flowing in the relief path is provided. 3. The workpiece gripping device according to claim 1, wherein the bypass switching valve is not in the shut-off position when a command for switching the main switching valve from the first switching position to the second switching position is input. A workpiece gripping device comprising a warning control means for outputting a warning signal in a case. 4. A clamp mechanism for gripping a workpiece, and a clamp cylinder on which a piston is operated by supplying a working fluid to a first working chamber and a second working chamber formed on both sides of the piston, The clamp mechanism is switched between the unclamped state and the clamped state by the operation of the piston of the clamp cylinder, and a temporary clamp position is set between the unclamped position and the main clamp position as the piston switched position of the clamp cylinder. In the workpiece gripping device, comprising a fixed amount dispensing cylinder having a smaller capacity than the clamp cylinder,
The first working chamber of the first working chamber and the second working chamber formed on both sides of the piston is connected to the second working chamber of the clamp cylinder.
A first switching position, connected to a working chamber, for supplying a pressurized fluid to a first working chamber of the clamp cylinder and for allowing fluid in a second working chamber of the fixed quantity distributing cylinder to escape, and for a second working chamber of the fixed quantity distributing cylinder. A main switching valve capable of switching to a second switching position for supplying a pressure fluid and releasing a fluid in a first working chamber of the clamp cylinder; and a main switching valve between the main switching valve and the second working chamber of the clamp cylinder. A bypass switching valve that is provided in a bypass passage that bypasses the quantitative distribution cylinder and that is switched between a communication position that communicates with the bypass passage and a blocking position that blocks the bypass passage; 2 With the fluid transferred to the working chamber, the piston of the clamp cylinder is switched to the temporary clamp position. Stroke position detecting means for detecting a stroke position of the fixed quantity distributing cylinder, and the clamp cylinder from a state where the main switching valve is switched to a second switching position and a bypass switching valve is switched to a communication position. When returning both pistons of the metering cylinder to the reverse position, the bypass switching valve is first switched to the shut-off position, and then the main switching valve is switched to the first switching position. And a switching control means for switching the bypass switching valve to the communication position after the stroke position detecting means detects that the workpiece has returned. 5. A clamp mechanism for gripping a workpiece, and a clamp cylinder for operating the piston by supplying a working fluid to a first working chamber and a second working chamber formed on both sides of the piston, The clamp mechanism is switched between the unclamped state and the clamped state by the operation of the piston of the clamp cylinder, and a temporary clamp position is set between the unclamped position and the main clamp position as the piston switched position of the clamp cylinder. In the workpiece gripping device, comprising a fixed amount dispensing cylinder having a smaller capacity than the clamp cylinder,
The first working chamber of the first working chamber and the second working chamber formed on both sides of the piston is connected to the second working chamber of the clamp cylinder.
A first switching position, connected to a working chamber, for supplying a pressurized fluid to a first working chamber of the clamp cylinder and for allowing fluid in a second working chamber of the fixed quantity distributing cylinder to escape, and for a second working chamber of the fixed quantity distributing cylinder. A main switching valve capable of switching to a second switching position for supplying a pressure fluid and releasing a fluid in a first working chamber of the clamp cylinder; and a main switching valve between the main switching valve and the second working chamber of the clamp cylinder. A bypass switching valve that is provided in a bypass passage that bypasses the quantitative distribution cylinder and that is switched between a communication position that communicates with the bypass passage and a blocking position that blocks the bypass passage; 2 With the fluid transferred to the working chamber, the piston of the clamp cylinder is switched to the temporary clamp position. Uni constructed and workpiece gripping device is characterized by providing a stop in the middle of the bypass passage. 6. The non-return valve according to claim 5, wherein a flow of the fluid in the direction from the second working chamber of the clamp cylinder to the main switching valve is prevented only in parallel with the throttle. A workpiece gripping device comprising: 7. A workpiece gripping device according to claim 4, wherein said bypass switching valve is at a shut-off position, and said bypass switching valve is at a shut-off position. And a switching inhibiting means for inhibiting switching of the main switching valve from the first switching position to the second switching position when the main switching valve is not present. 8. The workpiece gripping device according to claim 7, wherein the pressurized fluid supplied from the main switching valve to the first working chamber of the clamp cylinder only when the bypass switching valve is switched to the shut-off position. And a fluid detecting means for detecting whether or not fluid is flowing in the relief path. 9. The workpiece holding device according to claim 7, wherein the bypass switching valve is not in the shut-off position when a command for switching the main switching valve from the first switching position to the second switching position is input. A workpiece gripping device comprising a warning control means for outputting a warning signal in a case.