JPS625840Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a failure detection circuit for a safety fence for a press that detects a failure by the operation of a lower limit position detector of the safety fence provided in a press machine.

Conventional press machines have been designed to ensure worker safety.
There is a safety fence that can be opened and closed. In addition, when the safety fence is lowered to the lower limit position, a lower limit position detector is provided to detect this, and the press machine can only be operated by the operation ready signal from this lower limit position detector. If this lower limit position detector fails, the lower limit position detector will issue an operation ready signal even if the safety fence is at a position other than the lower limit position, and there is a risk that worker safety may not be ensured.

This invention was made for the purpose of improving this problem, and the failure detection of the safety fence for presses detects failure of the safety fence depending on whether or not the detector that detects the lower limit position of the safety fence is operating normally. It provides a circuit that allows press work to be carried out safely.

This invention will be explained below with reference to an embodiment shown in the drawings. In the drawing, 1 is a main body of a press machine, and a safety fence 2 that can be opened and closed in the vertical direction is provided on the front and rear surfaces. In addition, there is a safety fence 2 near the safety fence 2 mentioned above.
Detector 3 and safety fence 2 that turn on when the is at a position other than the lower limit position and turn off when lowered to the lower limit position.
Lower limit detectors 4 (both are switches) are installed vertically apart from each other, and are turned off when the detector is at a position other than the lower limit position, and turned on when the lower limit position is lowered to the lower limit position. Normally closed contact 3b of the detector 3 and normally open contact 4 of the lower limit detector 4
a are connected in series to a relay 7 provided between lines 5 and 6, a relay 8 connected in parallel to this relay 7, and a normally open contact 7-3 of the relay 7,
Normally open contact 7-1 of relay 7 and normally open contact 9 of relay 9
-1 connected in series via a parallel circuit. Note that 10 indicates an indicator light connected in parallel to the relay 8.

On the other hand, the normally open contact 3a of the detector 3 and the normally closed contact 4b of the lower limit position detector 4 are also connected in series.
Further, the normally closed contact 7-2 of the relay 7 provided between the lines 5 and 6 is connected in series to the relay 9, and the normally open contact 3a, the normally closed contact 7-2, and the normally closed contact 7- of the relay 7 are connected in series. Normally closed contact 4 of relay 8 is connected to the series circuit of 2.
-2 and the normally open contact 9-3 of the relay 9 are connected in series.

The series circuit of the normally open contact 8-1 of the relay 8 and the normally closed contact 9-2 of the relay 9 is a press interlock circuit.

Next, to explain the operation, before the press work starts or in the state shown in FIG. 2 where the safety fence 2 is not at the lower limit position, the detector 3 is on and the lower limit detector 4 is off, so the detector 3 Since the normally closed contact 3b of the lower limit detector 4 is turned off and the normally open contact 4a of the lower limit detector 4 is turned off to form the circuit shown in FIG.
is not energized, and each relay 7, 8 is turned off.

Also, the relay 9 is energized via the normally open contact 3a of the detector 3, the normally closed contact 4b of the lower limit detector 4, and the normally closed contact 7-2 of the relay 7, and this relay 9 is connected to the normally closed contact 8-2 of the relay 8. 2 and its own normally open contact 9-3 to turn off the normally closed contact 9-2 of the press interlock circuit, making it impossible for the press machine to operate.

Next, when the safety fence 2 is lowered to the lower limit position shown in FIG. 1 to start press work, the detector 3 turns off and the lower limit detector 4 turns on, forming the circuit shown in FIG. 4 (b). Therefore, the normally closed contact 3b of the detector 3
and the relay 7 via the normally open contact 4a of the lower limit detector 4 and the normally open contact 9-1 of the self-held relay 9.
is energized, and the relay 7 is turned on. When the relay 7 is turned on, the normally open contacts 7-1 and 7-3 of the relay 7 are turned on and the relay 8 is energized, so the relay 8 is turned on and the normally closed contact 8-2 is turned off. Since the self-holding of the relay 9 is released by It becomes possible to operate the press machine.

Next, when performing a major
When the lower limit position shown in the figure is raised to the position shown in Figure 2, the detector 3 is turned on and the lower limit detector 4 is turned off, resulting in the circuit shown in Figure 4A again, and the relay 9 is self-held and the interlock is activated. The circuit becomes activated and the press machine becomes unable to operate.

Therefore, the press machine does not operate inadvertently during the die-cutting process, and the die-cutting process can be carried out safely.

Next, when the safety fence 2 is lowered again to the position shown in FIG.
is off, the lower limit detector 4 is turned on, forming the circuit shown in FIG.
However, the relay 8 is held by the normally open contacts 7-1 and 7-3 of the relay 7, and the indicator light 10 connected in parallel with the relay 8 lights up, and when the relay 8 is turned on, the normally closed contact 8- 2 is turned off, the self-holding of the relay 9 is released, and the normally closed contact 9-2 of the relay 9 and the normally open contact 8-1 of the relay 8 are both turned on, the interlock of the interlock circuit is released, and the press machine becomes possible to drive.

As described above, when the safety fence 2 is raised from the lower limit position, the relay 9 is self-retained, and the safety fence 2 is raised in the previous process.
When the safety fence 2 reaches the lower limit position again, the self-holding of the relay 9 is released and the press machine can be operated. If the safety fence 2 is opened/closed, the operating order of the detectors 3 and 4 will not be as described above, so the press machine 1 will not be able to operate even if the safety fence 2 is closed, and the detectors 3, 4
It becomes possible to detect failures.

As detailed above, this device is equipped with a detector near the safety fence that detects when the safety fence is at a position other than the lower limit position, and a detector that detects when the safety fence is at the lower limit position. This system memorizes when the lower limit position detector has turned off, and allows the press machine to operate only when the lower limit position detector turns on again, which may result in a malfunction of the lower limit position detector, etc. If this happens, the press machine will be unable to operate, which improves the safety of the workers and also makes it easier to detect malfunctions in the lower limit position detector, etc.

[Brief explanation of the drawing]

The drawings show one embodiment of this invention, and Fig. 1 is an explanatory diagram of the lower limit position of the safety fence, Fig. 2 is an explanatory diagram of positions other than the lower limit position of the safety fence, Fig. 3 is a circuit diagram, and Fig. 4 A and B are explanatory diagrams. It is an action explanatory diagram. 1 is a press machine, 2 is a safety fence, and 3 and 4 are detectors.

Claims (1)

[Scope of utility model registration request] When the safety fences 2 provided before and after the press machine 1 are at the upper limit position, the safety fences 2
The detector 3 is turned on when the safety fence 2 is at the lower limit position and turned off when the safety fence 2 is at the lower limit position, and the detector 3 is turned on when the safety fence 2 is at the lower limit position and is turned off when the safety fence 2 is above the lower limit position. a lower limit detector 4,
It is connected in series with the normally closed contact 3b of the detector 3, the normally open contact 4a of the lower limit detector 4, and the normally open contact 9-1 of the relay 9, and is turned on when the safety fence 2 reaches the lower limit position. A relay 7 that is self-held by its own normally open contact 7-1 and a normally open contact 7 of the relay 7
-3, the normally open contact 3a of the detector 3, the normally closed contact 4b of the lower limit detector 4, and the normally closed contact 7 of the relay 7 when the safety fence 2 is above the lower limit position. 2, the normally closed contact 8-2 of the relay 8 is self-held by its own normally open contact 9-3, and is turned on when the safety fence 2 reaches the lower limit position.
The relay 9 is turned off by the relay 9, the normally closed contact 9-2 of the above-mentioned relay 9, and the normally open contact 8-1 of the relay 8, and when both are turned on, the interlock is released and the press machine 1 is operated. A failure detection circuit for press safety fences consisting of an interlock circuit and an interlock circuit.