JPS589319B2 - How to read the press report - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting an abnormality in a solenoid valve for controlling clutch brake operation of a press machine having a friction type clutch brake.

Conventional double-drop prevention measures for presses include a double solenoid self-guard system, but this method is not only complex and expensive, but also requires multiple valves to be operated at the same time. During work, the exhaust characteristics of the valve deteriorate, resulting in a delay in the start time of brake operation, which has the disadvantage of impairing the stopping characteristics of the brake.

When investigating double-drop accidents due to abnormalities in solenoid valves during fluid circuit abnormalities, we found that normally solenoid valves have three-way openings that are normally closed for safety reasons, and when the solenoid is energized, the clutch cylinder is Pressure is supplied, the clutch connects, and the press starts, and the solenoid is demagnetized, which releases the fluid pressure in the clutch cylinder and activates the brake. However, if the solenoid valve malfunctions due to disconnection of the solenoid, the clutch cylinder The internal pressure is immediately exhausted and the brakes are activated, so there is no chance of a double fall accident.

The cause of double drop due to an abnormality in the solenoid valve is that even though the solenoid has been demagnetized in response to a stop signal, the clutch remains connected without being exhausted due to a malfunction in the spool or the like.

The present invention eliminates this drawback, and uses one ordinary solenoid valve to operate the clutch brake so as not to damage the brake characteristics during regular press operations, and prevents abnormalities in the solenoid valve from occurring in advance. It is an object of the present invention to provide a method for detecting an abnormality in a solenoid valve for a friction type clutch brake, which makes it possible to detect an abnormality in a solenoid valve for a friction type clutch brake and to extract an output for preventing double drop due to an abnormality in a fluid circuit.

The present invention will be described with reference to the drawings of one embodiment.
Figure 1 shows a clutch cylinder for operating the clutch of the press, 2 is a solenoid valve for supplying and discharging pressure to clutch cylinder 1, and 6 is placed on the pressure pipe that connects clutch cylinder 1 and solenoid valve 2. When there is no pressure in the small diameter cylinder 6, a piston 5 is pressed against the end as shown in FIG. 1 by a spring 4, and a piston 3 is pushed out to the other end of the cylinder by pressure It is a proximity switch to detect that

By energizing the electromagnetic valve 2 with a press start signal, pressure is supplied to the clutch cylinder 1, a clutch (not shown) is connected, and the press starts operating.

At this time, the piston 5 overcomes the spring 4 and moves in the y dimension, activating the proximity switch 3.

By demagnetizing the solenoid valve 2 with a stop signal and discharging the pressure, the pressure inside the clutch cylinder is also discharged, and the press brake (not shown) is activated to stop the press. In this case, the piston 5 is returned to its original position by the force of the spring 4. Therefore, the activation signal of the proximity switch 3 is cut off.

2 and 2a are the coils of the solenoid valve 2, and 7 is the coil 2a.
This is a detection device for detecting the presence or absence of a voltage.

Figure 3 is a graph of the pressure drop in the clutch cylinder when the solenoid valve 2 is deenergized by a stop signal. P1 is the working pressure of the clutch cylinder during regular work, and P2 is the pressure that is overcome by the brake spring of the press. This is the pressure that returns the clutch piston to the brake side.

The pressure of P3 is E. I. G. H. This is the pressure that is normally on the way down to 0 atm along the line, and is a safety confirmation pressure that can definitely drop to 0 atm after P1 drops to P3.

FIG. 4 is a diagrammatic representation of a suppression logic circuit for abnormality detection according to the present invention in which a voltage is generated at C only when there is no input voltage at A and there is voltage at B.

The timer T is set to a time t that is Δ1 longer than the time t required for the pressure to normally drop from P1 to P3, and starts counting at point E, that is, at the press stop signal.

The piston 5 is balanced by the force of the spring 4, which has the same force as the output of the cylinder 6 due to the pressure of P3, and during the period E→■ (t seconds), it is in contact with the proximity switch 3, and there is no voltage at B. ing.

Under normal conditions, a voltage is generated at C for t seconds, but since it is less than t' seconds of timer T, the voltage is cut off by timer T and no output is generated.

When an abnormality occurs in the solenoid valve and the pressure does not drop and t seconds pass along EF, the timer set (cutoff time) time will be overrun, so the clutch cylinder will not be exhausted even though the solenoid voltage has been cut off. Abnormal conditions can be detected by generating voltage due to the activation of the proximity switch and no voltage by the solenoid, passing through the inhibition logic circuit, and furthermore by the condition that the timer is outside the set time, and can be extracted as an output, etc. This is a method for detecting an abnormality in a solenoid valve for a friction clutch in a press machine, which makes it possible to operate a valve for preventing double-dropping.

According to the method of the present invention having the above-described configuration and operation, the structure is simple, and since only one solenoid valve is used, it is inexpensive, and there is no deterioration in exhaust performance and the stopping characteristics of the brake are not impaired. Since an abnormality in the exhaust state of the electromagnetic valve for brake operation is detected in advance, it is possible to prevent a double drop due to an abnormality in the electromagnetic valve.

[Brief explanation of the drawing]

Fig. 1 is an air circuit diagram to the clutch cylinder of the first embodiment of the present invention, Fig. 2 is an electric circuit diagram of a detection device that detects the presence or absence of coil voltage of a solenoid valve, and Fig. 3 is a stop signal for the solenoid valve. FIG. 4 shows a diagram of the pressure drop in the clutch cylinder when deenergized by the clutch cylinder, and FIG. 4 shows the inhibition logic circuit diagram used in the present invention. 1 is a clutch cylinder, 2 is a solenoid valve, 3 is a proximity switch, 4 is a spring, 5 is a piston, 6 is a cylinder, and 7 is a detection device.

Claims (1)

[Claims] 1. A small diameter cylinder that can be reset by a spring is installed between the fluid path of the electromagnetic valve that controls the clutch cylinder that operates the friction clutch of the press machine, and pressure is supplied to the clutch cylinder to confirm the fluid path in advance. The piston is configured to move and activate the proximity switch when the safety pressure exceeds the specified safety pressure, and the output is generated only when the voltage at the coil terminal of the solenoid valve is 0 and voltage is generated by activation of the proximity switch. A timer that operates with the output as an input is set at a time when the fluid path drops from normal pressure to safe pressure after the coil terminal voltage of the solenoid valve becomes O. If the pressure in the fluid path, that is, the pressure inside the clutch cylinder does not drop even after a set time, it is assumed that an abnormality has occurred and is taken out as the final output, thereby preventing deterioration of the exhaust characteristics of the press's clutch solenoid valve and abnormalities in the clutch brake. A method for detecting abnormalities in solenoid valves for friction clutches in press machines.