JPH0329027Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a contact welding detection circuit for a press machine.

(Prior art) In a press machine, for example, as shown in FIG. 2, an upper die 11 is attached to a ram 12 and a lower die 13 is attached to a bolster 14, and a solenoid drive contact is closed when an operation switch is turned on. As a result, the solenoid is activated and the ram 12 is lowered and then raised, and the sheet metal inserted between the upper mold 11 and the lower mold 13 is processed by the upper mold 11 and the lower mold 13.

(Problem to be solved by the invention) In the press machine mentioned above, if the solenoid drive contact is welded, the solenoid remains activated and the ram 12 repeats up and down reciprocation even if the operation switch is turned off, so the press work is difficult. It is extremely dangerous.

(Means for solving the problem) The present invention is a contact welding detection circuit for a press machine in which a solenoid is actuated by closing a solenoid drive contact to reciprocate a ram. The present invention is characterized in that a detecting means is provided, which is connected to a drive power source through each of the solenoid drive contacts, and detects that only one of the two solenoid drive contacts is closed.

(Function) The detection means detects that only one of the two solenoid drive contacts is closed.

(Example) FIG. 1 shows an embodiment of the present invention.

This embodiment is used as a contact welding detection circuit for the press machine shown in FIG.
and a photocoupler consisting of light emitting diodes 17, 18 and phototransistors 19, 20, resistors 21, 22, detection circuits 23, 24, a driver 25, a relay 26 having normally closed contacts 260 to 262, a light emitting diode 27, and A resistor 28 is provided. Solenoid drive contact 15,
Reference numeral 16 denotes a normally open contact of a relay that is activated when the operating switch is turned on, and is connected between both ends of the solenoid 29 and both ends of its driving power source (AC power source) via contacts 261 and 262, respectively.

When the two solenoid drive contacts 15 and 16 close simultaneously by operating the operating switch and turning it on, the solenoid 29 is driven by the drive power source, and the ram 12 descends once, rises, and stops.
A sheet metal inserted between the upper mold 11 and the lower mold 13 is processed by the upper mold 11 and the lower mold 13. At this time, the light emitting diodes 17 and 18 are connected to the resistors 21 and 2, respectively.
2. The solenoid drive contacts 15 and 16 are momentarily energized by the drive power supply to turn on the light, turning on the phototransistors 19 and 20 for a moment, but the detection circuits 23 and 24 do not operate for a short period of time.

When the solenoid drive contacts 15 and 16 are open, the light emitting diodes 17 and 18 are not energized and are turned off. When one solenoid drive contact 15 is welded and closed, and the other solenoid drive contact 16 is opened, the light emitting diode 17 lights up and the phototransistor 19 is turned on, and after a certain period of time, the detection circuit 23 When the driver 25 operates to drive the relay 26 and the light emitting diode 27, the relay 26 is self-held by the relay contact 260. Therefore, the normally closed contact 26 of the relay 26
1,262 opens and the drive power is cut off, and the light emitting diode 27 lights up to warn of welding of the solenoid drive contacts. Also, the solenoid drive contact 16 is welded and closed, and the solenoid drive contact 1 is closed.
5 opens, the light emitting diode 18 lights up and the phototransistor 20 turns on, and after a certain period of time, the detection circuit 24 operates and the driver 25
When the relay 26 and the light emitting diode 27 are driven, the relay 26 is self-held by the relay contact 260. Therefore, the normally closed contacts 261, 2 of the relay 26
62 opens to turn off the drive power, and the light emitting diode 27 lights up to warn of welding of the solenoid drive contacts. Self-holding of relay 26 is done by turning off the power.
It will not be canceled unless it is turned OFF.

(Effects of the invention) As described above, according to the invention, in a contact welding detection circuit of a press machine in which the solenoid is actuated by the closing of the solenoid drive contact to reciprocate the ram, both ends of the solenoid are connected to two solenoids. Since the drive contacts are connected to the drive power source through each contact and it is detected that one of the solenoid drive contacts is welded, it is possible to prevent the solenoid from remaining activated due to welding of the solenoid drive contacts. This makes it possible to perform press work safely.

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing one embodiment of the present invention;
The figure is a schematic diagram showing an example of a press machine.

Claims (1)

[Scope of utility model registration request] In a contact welding detection circuit for a press machine in which a solenoid is actuated by closing a solenoid drive contact to reciprocate a ram, both ends of the solenoid are connected to a drive power source through two solenoid drive contacts, and the above 1. A contact welding detection circuit comprising a detection means for detecting that only one of the two solenoid drive contacts is closed.