JPS5916160B2 - Safety devices in presses - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides that during the downward stroke of the press slide,
The present invention relates to a safety device for a press that prevents injuries and accidents by abruptly stopping the downward movement of the press slide when a worker intervenes in a dangerous area such as below the slide of the press and its surroundings.

Conventionally, press machines have been equipped with a safety device that suddenly stops the operation of the press slide to prevent injuries if a worker intervenes in a dangerous area such as below or around the press slide. There are many things it has.

By the way, in a normal press, even if a worker intervenes in the danger zone, there is no danger while the press slide is on its upward stroke (but it can be prevented if the operation is suddenly stopped only when it is on its downward stroke). Therefore, in order to shorten the interruption time of the press operation as much as possible and not reduce work efficiency, a limit switch is provided that operates in conjunction with the upward stroke of the press slide, and when the limit switch is activated, an emergency stop function of the press slide is activated. Many devices are now configured to disable the .

However, in the case where the emergency stop function is disabled during the upward stroke of the press slide as described above, if the limit switch that operates during the upward stroke of the press slide malfunctions for some reason and its contact remains closed, In other words, if the contacts are fused, the emergency stop function will remain disabled even if the press slide moves to the downward stroke, so if this situation occurs, the press's safety device will not operate at all (
It is extremely dangerous.

In view of the above, the present invention includes a limit switch provided in conjunction with the upward stroke of the press slide, and another electrical contact that operates in the same way as the limit switch.
By configuring a circuit that activates the press's emergency stop device when one of the contacts becomes welded, even if the limit switch fails for some reason and its contact becomes welded, the press will still be able to operate. DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention aims to provide a safety device for a press that can immediately stop operation to ensure safety.The configuration of the present invention will be described below with reference to a preferred embodiment shown in the drawings.

LS1 and LS2 are limit switches, and the limit switch LS1 is provided so as to be linked to the upward stroke of the press slide (the stroke from the bottom dead center to the top dead center of the press slide), and the limit switch LS2 is is attached to limit switch LS1 so that it operates in the same way as limit switch LS1.

The limit switch LS1 has fixed contacts A, B and a movable contact C that alternately opens and closes, and the limit switch LS2 has the same fixed contacts A, B/ and a movable contact C'.

Fixed contact A of limit switch LS1 is resistor R
1. The fixed contact B is connected to a resistor R2, the fixed contact AI of the limit switch LS2 is connected to a resistor R3, the fixed contact B' is connected to a power source B through a resistor R4, and furthermore, the limit switch LS1. The movable contacts c and c' of LS2 are each connected to the ground side.

Also, ■C1 to IC4 are logic circuits, of which I
C1゜IC2 and IC4 are NOR circuits, IC3 is OR circuit
It is a circuit.

And inputs ■ and ■ of circuit IC0 are limit switches L
S1. Connected to fixed contacts A and AI of LS2, respectively,
Its output ■ is connected to one input 0 of circuit IC4, and circuit ■C20 inputs ■ and ■ are limit switch LS1.
．． Connected to fixed contacts B and B' of LS2, respectively,
Its output ■ is connected to the other input @ of the circuit IC4.

One input ■ of the circuit ■C3 is connected to the output ■ of the circuit ■C2, and the other input ■ is connected to the output side 2 of a light beam safety device (not shown).

This optical safety device switches the signal when the light beam between the light emitting element and the light receiving element is interrupted by a working means.Normally, an H signal is sent to the output side Z, and when the light beam is interrupted, the signal changes. It is configured so that an L signal is sent out.

Xl is a relay, and Trl is a transistor, and these constitute a control circuit for the emergency stop device of the press slide.

That is, the switching contact of relay X is connected to the emergency stop circuit side, and the base of transistor Tr1 is connected to the circuit ■C3.
A relay X1 is connected between its collector and a switching contact of a relay X2, which will be described later.

Relay X and transistor Tr2 are circuit elements constituting the circuit power supply control device of the emergency stop device, and the base of transistor Tr1 is connected to the output [phase] of circuit IC, and the relay X2 is connected between its collector and B power supply earth. The switching contact of relay X2 is connected to the B power supply.

In the configuration as on paper, when the press slide is in its downward stroke, the limit switch LS1. LS2 contacts are C-A, C
'-A' is connected, and when moving to the upward stroke, those contacts C-B and C'-B' are connected.

When the press slide is in the downward stroke, the input of the circuit C1 is L1, so its output is H1.The input of C2 is H1, so the output is L. , so the input 0. of circuit IC4. @ is H, L
, its output [phase] becomes L, transistor Tr2 is not conductive, and relay X2 is not attracted (power is supplied to the control circuit of the emergency stop device in the non-adsorbed state).

On the other hand, the circuit ■C30 input ■ is L, and the output Z is H when the light beam of the optical safety device is not interrupted, that is, when no worker intervenes in the danger area of the press. The input ■ is H, and its output ■ is H
becomes.

Therefore, the transistor Tr becomes conductive, the relay X1 becomes a suction state, and the emergency stop device of the press is held in a non-operating state.

By the way, in the above state, if a worker intervenes in the danger area of the press, the output Z becomes L and the circuit IC
30 input ■ is inverted, so the output ■ of the circuit ■C3 is L
As a result, the transistor Trl becomes non-conductive, the relay X1 is switched in the direction in which the emergency stop device of the press is activated, and the downward movement of the press slide is suddenly stopped.

When the press slide moves from the bottom dead center to the upward stroke, the limit switch LS1. If the operation of LS2 is normal, its contacts will switch to C-B and C'-B', but in this state, the circuit ■C1 and IC20 inputs are inverted, and the input ■ becomes H1.
■ becomes H1, ■ becomes L, output ■ becomes H, and ■ becomes H, so the input of the circuit IC is 0, @ is Hl, the output [phase] becomes L, and the output [phase] becomes L, and the output [phase] becomes L. Maintains the state in which power is supplied to the control circuit.

However, in this state, even if a worker intervenes in the dangerous area of the press and the output Z becomes L, the input of the circuit C3 becomes H1, and its output becomes H and the transistor T
Since r1 is conductive and relay X1 is maintained in a state where the emergency stop device of the press is not activated, the press slide will not suddenly stop and the emergency stop function will be disabled.

In addition, even if the output Z is H in this state (a state in which workers do not intervene in the dangerous area), the output of circuit ■C3
Since is H, the emergency stop function is similarly disabled.

By the way, if one of the contacts of limit switch LS or LS2 becomes welded for some reason and, for example, the contact of limit switch LS1 remains connected to C-H even when the press slide starts its downward stroke, the circuit will be damaged. ■C1
0 input ■ is H1 circuit ■ C2 input ■ is circuit IC because L1 limit switch LS2 is switched to C/A/
1's input (2) and circuit (2) C20 input (2) become H, and their outputs (2) and (2) become L.

Therefore, circuit IC40 input 0. The output [phase] becomes H, transistor Tr2 becomes conductive, and relay X2 operates in the direction of cutting off the power to the control circuit of the emergency stop device, so the emergency stop device operates and the press slide stops. Safety is ensured by making a sudden stop.

Note that the same operation is performed even when the limit switch LS1 is normal and the limit switch LS2 is abnormal.

In addition, even if a failure occurs in the contacts of relay X2, circuit ■C3
As mentioned above, the input ■ is L, so if a worker intervenes in the danger area of the press and the input signal becomes Z or L, the output ■ of the circuit C3 becomes L, and therefore the transistor Tr2 will not conduct, the press slide will suddenly stop, and normal safety will be ensured.

In short, the present invention includes an emergency stop device that suddenly stops the press slide when a worker intervenes in the dangerous area of the press slide during the downward stroke of the press slide, and the emergency stop device A limit switch that disables the limit switch and another electrical contact that operates in the same way as the limit switch are provided, and a circuit power control device for the emergency stop device of the press is provided, and the limit switch and the electrical contact attached thereto, Since a circuit is configured to operate the circuit power supply control device to an emergency stop state of the press when one of the contacts is fused, the emergency stop device is disabled during the upward stroke of the press slide, and the interruption time of the press operation is Even if the limit switch is broken for some reason and its contacts become fused, the press operation should be stopped immediately to ensure safety at all times. It produces the effect that can be achieved.

[Brief explanation of the drawing]

The drawing is a circuit diagram of a device showing an embodiment of the present invention. LSl, LS2...Limit switch, IC1
~■C4...Logic circuit, Trl, Tr2...
...Transistor, Xl, X2...Relay.

Claims (1)

[Claims] 1. Equipped with an emergency stop device that suddenly stops the press slide when a worker, etc. intervenes in the dangerous area of the press during the downward stroke of the press slide, and disables the above emergency stop device in conjunction with the upward stroke of the press slide. A limit switch and another electric contact that operates in the same way as the limit switch are provided, and a circuit power control device for the emergency stop device of the press is provided, and the limit switch and the electric contact attached to it are used to control one of them. 1. A safety device for a press, comprising a circuit that operates the circuit power supply device to an emergency stop state of the press when the contacts are fused.