JP2911970B2 - Unclamp operation abnormality detection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for temporally detecting an abnormality in an unclamping operation in a fluid clamp driving device.

(Prior art)

The applicant of the present invention has proposed a clamp operating circuit in a patent application of Japanese Patent Application No. 1-77525.

The clamp operation circuit connects an operating cylinder for clamping and a detecting cylinder for detecting the operation of the operating cylinder in series in the piping line of the pressure fluid, and returns the operating cylinder and the detecting cylinder to their original positions respectively. Compensation means are connected in parallel, the movement position of the piston rod of the detection cylinder is detected by the position detection means, and the operation state of the working cylinder for clamping, that is, the operation state of the clamp / unclamp is detected by the detection cylinder and the position detection means. To detect indirectly.

In the above-mentioned clamp operation circuit, when the piston rod of the operation cylinder or the detection cylinder quickly returns to the unclamping position during the unclamping operation, the original position return compensating means on the cylinder side that has returned quickly exceeds the cracking pressure and is opened. In order to continuously pass the pressure fluid, the piston rod of the other cylinder continues to move in the unclamping direction, and a reliable return to the original or unclamped position is compensated.

[Problems of the prior art]

However, even if the piston rod of the working cylinder or detection cylinder stops for some reason such as hitting an obstacle during the unclamping operation, the unclamping operation is completed because the home position return compensation means is opened. The unclamping state is detected by the detecting cylinder and its position detecting means, though not performed. For this reason, even if the unclamped state is detected by the position detecting means, the working cylinder may not actually be in the unclamped state, thereby causing a malfunction.

[Object of the invention]

Therefore, an object of the present invention is to prevent a malfunction by detecting an abnormal operation state in advance.

[Solution of the Invention]

To achieve the above object, the present invention provides an unclamping abnormality detecting device in a fluid clamp driving device, a pressure switch in the fluid clamping driving device, and a timing comparison means in the unclamping abnormality detecting device. ing.

[Function of the invention]

During the unclamping operation, the timing comparing means compares the unclamping detection timing with the pressure response timing of the pressure switch, and outputs an abnormal signal when the pressure response timing precedes the unclamping detection timing.

As described above, the timing comparing unit detects an abnormality of the unclamping operation by detecting a state of a temporal change during the unclamping operation. Therefore, when an abnormal signal is generated, the operator checks the unclamping state, performs necessary operations, and then proceeds to the next step to prepare for an unexpected accident.

〔Example〕

In FIG. 1, a fluid-type clamp driving device 1 includes one or more clamping operation cylinders 2, one operation detection detection cylinder 3, original position return compensation means 4, 5, and position detection means 6, and the like. Is assembled,
A pressure fluid 7 for driving these, for example, pressure oil, is supplied by a pipe 9 from a pressure fluid source 8.

That is, the pressure fluid source 8 is connected to the input port of the directional control valve 12 at the position of the electromagnetically operated 4-port 3 through the pipe 9 via the check valve 10 and the relief valve 11. The two switching ports of the direction switching valve 12 are connected to the cylinder chambers 2a and 2b of the working cylinder 2 and the cylinder chambers 3a and 3b of the detection cylinder 3 via the pipe 9 and the rotary joint 17 of the reciprocating path and, if necessary, the throttle valve 38. Are connected in series.

The electromagnetic actuators 28 and 29 of the direction switching valve 12 are switched by a clamp operation switch 24 and a driver 26 and an unclamping operation switch 25 and a driver 27, respectively, and the switching state is maintained by a mechanical positioning mechanism. The return port of the direction switching valve 12 is connected to the tank 18.

The original position return compensating means 4 and 5 are respectively constituted by a check valve 13 and a throttle valve 15, a check valve 14 and a throttle valve 16 connected in series. These check valves 13 and 14 are connected in a direction in which a check function is performed with respect to the supply direction of the pressure fluid 7 during the clamping operation. Is opened.

In order to detect the movement of the piston rod 3c of the detection cylinder 3, the position detection means 6 determines the position of the dog 19 attached to the piston rod 3c by using a limit switch 20 for detecting unclamping, and a limit switch for detecting clamp.
21 and 22, and a limit switch 23 for detecting overstroke. Here, the clamp detection limit switches 21 and 22 correspond to workpieces of different sizes, and one of them is selected and used.

The unclamping operation abnormality detecting device 30 has a timing comparing means 37 and an alarm 33. The timing comparing means 37 is connected on the input side to the limit switch 20 and the pressure switch 34 for detecting unclamping, and is connected on the output side to the alarm 33. Pressure switch 34 above
Is a pipe 9 between the working cylinder 2 and the detection cylinder 3.
The pressure fluid 7 is provided in the flow path of the pipe 9 on the side that supplies the pressure fluid 7 during the unclamping operation.

When the directional control valve 12 is switched to the parallel flow path state in FIG. 1 and the pressure fluid 7 is supplied to the cylinder chamber 3b of the detection cylinder 3 and the cylinder chamber 2b of the plurality of working cylinders 2, The piston rods 2c and 3c are retracted to the unclamping positions as original positions. This state can be confirmed by, for example, an “H” level output signal from the limit switch 20 for unclamping detection.

In this state, when the operator or the controller turns on the clamp operation switch 24, drives the electromagnetic actuator 28 via the drawbar 26, and switches the flow path of the directional control valve 12 to the direction of the cross flow path, the pressure fluid source Since the pressurized fluid 7 from 8 is supplied to the cylinder chamber 2a of the working cylinder 2, the piston rod 3c moves forward and hits the work at the distal end portion, and is brought into a clamped state with a predetermined clamping force.

During this clamping operation, the pressure fluid 7 inside the cylinder chamber 2b is pushed out by the piston rod 2c and enters the inside of the cylinder chamber 3a of the detection cylinder 3, and the piston rod
3c is advanced, and the limit switch 21 for clamp detection corresponding to the workpiece being clamped by the dog 19 is turned on. Thereby, the clamp completion state can be confirmed.

Here, when all the working cylinders 2 are in the clamped state, the total flow rate of the pressure fluid 7 discharged from the cylinder chamber 2b is determined by the limit switch 21 corresponding to the workpiece whose piston rod 3c of the detection cylinder 3 is being clamped. It is the flow rate necessary to move forward.

During this clamping operation, the working cylinder 2 is always located on the upstream side of the detection cylinder 3 with respect to the supply direction of the pressurized fluid 7, so that the detection cylinder 3 is Prior to this, the clamp is not completed. Also, the original position return compensation means 4,
The check valves 13 and 14 inside 5 always function as a check,
It does not open to any pressure of the pressure fluid 7.

Next, when the operator or the controller turns on the unclamping operation switch 25 for the unclamping operation, the direction switching valve 12 becomes a parallel flow path,
The pressure fluid 7 from the pressure fluid source 8 first enters the cylinder chamber 3b of the upstream detection cylinder 3, and the piston rod
Retreat 3c. At this time, the pressure fluid 7 inside the cylinder chamber 3a enters the inside of the cylinder chamber 2b of the downstream working cylinder 2 and retreats the piston rod 3c, thereby setting an unclamped state. In the process of ending the unclamping, the dog 19 of the piston rod 3c hits the limit switch 20 for detecting the unclamping, so that the position detecting means 6 confirms the unclamping state.

During this unclamping operation, when the piston rod 3c hits an obstacle or the like and stops without completely retreating to the unclamping position, or returns to the original position earlier than the working cylinder 2, the cylinder chamber 3b of the detecting cylinder 3 The internal pressure gradually increases. This internal pressure is the check valve
If the cracking pressure exceeds 14, the check valve 14 is opened, so that the pressure fluid 7 for the unclamping operation is increased.
Is supplied to the cylinder chamber 2b of the working cylinder 2 over time while the flow rate is restricted by the throttle valve 16 through the open check valve 14.

Therefore, when an abnormal operation occurs on the side of the detection cylinder 3, the home position return compensation means 5 continuously supplies the pressure fluid 7 to the cylinder chamber 2 b of the working cylinder 2, thereby causing the piston rod 2 c of the working cylinder 2 to move. Pull back completely to the original position, taking more time than normal.

Conversely, when all the operating cylinders 2 return to the unclamping position earlier than the detection cylinder 3, the cylinder chamber
If the pressure fluid 7 is continuously supplied to 3b, when the internal pressure of the pipe 9 between the cylinder chamber 3a and the cylinder chamber 2b exceeds the cracking pressure of the check valve 13, the home position return compensation means 4 The check valve 13 is opened, and the throttle valve 15 flows into the tank 18 while restricting the flow rate. During this time, the detection cylinder 3 completely returns to the unclamping position.

As described above, in the course of the unclamping operation, in addition to the above-described abnormal operation, the working cylinder 2 and the detection cylinder 3 are not synchronized with each other due to a volume change due to a temperature change of the pressure fluid 7 and the unclamping position. When the return time points of the above are not coincident, the home position return compensation means 4 and 5
14 is opened to compensate for the complete return of the working cylinder 2 and the detection cylinder 3 to the original position while limiting the flow rate.

On the other hand, the timing comparing means 37 inside the unclamping operation abnormality detecting device 30 detects the input time of the signal from the unclamping detection limit switch 20, that is, the unclamping detection timing t1, and the input time of the pressure signal from the pressure switch 34. That is, the signal is compared with the pressure response timing t2, and an abnormal signal is output according to the input order.

For this reason, the timing comparison means 37 is provided with an AND gate or an AND gate that outputs an abnormal signal when the “H” level pressure switch 34 is input, on condition that the “L” level input signal from the unclamping detection limit switch 20 is input. It can be configured by a flip-flop that outputs an abnormal signal by an AND gate.

As shown on the left side of FIG. 2, if the unclamping operation is performed normally, the signal from the unclamping detection limit 20 changes to the “H” level, and then the input signal from the pressure switch 34 changes to the “H” level. Timing comparison means
37 does not generate an abnormal signal.

However, as shown on the right side of FIG.
When the unclamping limit switch 20 does not detect the unclamping condition, that is, while the input signal from the limit switch 20 is at the “L” level, the pressure switch
Since the input signal from H changes to the “H” level, the timing comparison means 37 is provided on condition that the pressure response timing t2 precedes the unclamping detection timing t1.
Regards the time as an abnormal operation, generates an abnormal signal, and activates the alarm 33.

[Other embodiments]

In the above embodiment, the original position return compensating means 4 and 5 are constituted by the check valves 13 and 14 and the throttle valves 15 and 16.
The home position return compensating means 4 and 5 can be configured by combining throttle valves 15 and 16 and sequence valves 39 and 40 as shown in FIG.

In the above-described embodiment, the timing comparing means 37 is configured by an electric circuit element. However, this function can also be realized in the field of a program using a control, arithmetic, and comparing function of a CPU or the like.

〔The invention's effect〕

According to the present invention, when the pressure response time of the pressure switch becomes earlier than the reference detection cylinder operation time during abnormal unclamping operation, this state is detected by the timing comparing means and an abnormal signal is generated. Unclamp detection can be prevented beforehand, and appropriate measures can be taken.

[Brief description of the drawings]

FIG. 1 is a piping diagram of a hydraulic clamp driving device and a block diagram of an unclamping operation abnormality detecting device. FIG. 2 is an operation explanatory view of the unclamping operation abnormality detecting device. FIG. 3 is a piping diagram of another embodiment of the in-situ return compensation means. DESCRIPTION OF SYMBOLS 1 ... Fluid type clamp drive, 2 ... Working cylinder, 3 ...
Detection cylinder, 4, 5: Original position return compensation means, 6: Position detection means, 7: Pressure fluid, 8: Pressure fluid source, 9: Piping,
12 ... electromagnetically operated directional switching valve, 13, 14 ... check valve, 15, 16 ... throttle valve, 24 ... clamp operation switch, 25 ...
Unclamp operation switch, 30 ... Unclamp operation abnormality detection device, 33 ... Alarm, 34 ... Pressure switch, 37 ... Timing comparison means.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B23Q 17/00 B23Q 3/06 B25J 15/00

Claims (1)

(57) [Claims] An operating cylinder for clamping and a detecting cylinder for detecting the operation of the operating cylinder are connected in series in a piping line of a pressure fluid, and each of the operating cylinder and the detecting cylinder has a throttle function. An in-situ return compensation means is connected in parallel, and the movement position of the piston rod of the detection cylinder detects the movement of the working cylinder by the position detecting means. A timing in which a pressure switch is provided in a pipeline on a supply side of a pressure fluid during an unclamping operation in a pipeline, and an abnormal signal is output when a pressure response timing of the pressure switch is earlier than an unclamping detection timing by the position detecting means. An unclamping operation abnormality detecting device, comprising a comparing means.