JPH0133280B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a safe operation circuit for a press that increases safety by stopping operation of the press when an abnormality occurs in the press.

Various safety circuits are incorporated into the operating circuit of the press. Conventionally, to increase safety, important control parts such as clutch relays, restart prevention relays, fixed position stop rotary cams, restart prevention rotary cams, and safety-stroke rotary cams were equipped with two relays, switches, etc. . It is true that using two relays at a time is highly safe, but it was not possible to discover any abnormalities in each relay or switch itself.

The present invention can immediately discover such abnormalities,
This was done to increase safety by operating an emergency stop circuit.

Therefore, the present invention connects the a-contacts of each relay of the important control section in series, connects the b-contacts connected in series in parallel to the a-contact, and connects the parallel-connected ones in series. , and an off-delay timer is connected to that circuit. The contacts of this off-delay timer are connected to an emergency stop circuit.

The illustrated embodiment will be described below. A voltage is applied between lines 1 and 2. Between this line are fixed position stop rotary cam switches 3, 4, a circuit of fixed position stop relays 5, 6 operated by this switch, safety-stroke rotary cam switches 7, 8, and a circuit of fixed position stop relays 5, 6 operated by this switch. The circuits of the safety stroke relays 9 and 10, the restart prevention rotary cam switches 11 and 12, and the restart prevention relays 13 and 14 are connected, respectively. Furthermore, contact 15a of off-delay timer 15, which will be described later.
A series circuit between the set button 16 and an abnormality relay 17 for detecting an abnormality, and a series circuit between a contact 17b of this abnormality relay 17 and a lamp 18 are connected. A voltage is applied between the line 19 and the line 2 via the contact 17a of the abnormality relay 17. Between this line 19 and line 2, press clutch relays 20 and 21 are connected to operation buttons 22 and 2.
3. Contacts 24a of restart prevention relays 24 and 25,
25b and a contact 26a of the press clutch auxiliary relay 26. Similarly, a clutch solenoid valve 27, a press clutch relay 20,
21 contacts 20a and 21a are restart prevention relay 2
4, 25 through contacts 24b, 25b, through contacts 5a, 6a of fixed position stop relays 5, 6, and further through these contacts 5a, 6a and contacts 9a, 10a of the safety-stroke relay. has been done.
Further, restart prevention relays 24 and 25 are connected via contacts 20b and 21b of press clutch relays 20 and 21 and contact 26b of auxiliary relay 26, and a series circuit of these contacts 20b, 21b and 26b includes: Self-holding contact 24b in parallel,
25b is connected. The circuit for operating each relay connected between the lines 19 and 2 is not particularly new, but is a commonly used circuit. In addition, the contact 24 of the restart prevention relay 24 is connected to the contact 17a of the abnormality relay 17.
c, or contact 20 of press clutch relay 20
A lamp 27 circuit connected via c to indicate that the press is ready for operation is also commonly used.

The off-delay timer 15 is connected between the lines 1 and 2 via a circuit in which the contacts of the respective relays are connected in series and parallel. This contact group includes a series circuit of B contacts 20y and 21y connected in parallel to a series circuit of A contacts 20x and 21x of press clutch relays 20 and 21, and a series circuit of B contacts 20y and 21y of the press clutch relays 20 and 21, and a series circuit of B contacts 20y and 21y of the press clutch relays 20 and 21. A parallel circuit of a series circuit of 5x, 6x and a series circuit of B contacts 5y, 6y is connected, and the A contacts 9x, 10x, B contacts 9y of safety-stroke relays 9, 10 are similarly connected as shown in the figure. , 10y, a of restart prevention relays 13 and 14
Contacts 13x, 14x, B contacts 13y, 14y, and A contacts 24x, 2 of restart prevention relays 24, 25
5x, b contacts 24y, 25y. That is, off-delay timer 15
is connected in series to this contact group and the test button 28. The contact 17a of the abnormality relay 17 is connected to the line 19 as described above, the contact 17b is connected in parallel to the set button 16 for self-holding, and the contact 17c is connected to the lamp 18 in series. This lamp 18 is incorporated into a test button 28.

In explaining the operation of the above circuit, the circuit portion for starting the press will be omitted since it is conventionally known. Since the test button 28 remains on unless the test button 28 is pressed, the contact 15a of the off-delay timer 15 is turned on at the same time as the power is turned on by the B contacts connected in series in the contact group. Therefore, by turning on the set button 16, the abnormality relay 17 is turned on, and its contact 17 is turned on.
A voltage is applied between lines 19 and 2 via a to enable operation. Also, in this way, the abnormality relay 17
When turned on, the contact 17b is turned on and the abnormality relay 17 is self-retained, so that the operable state is maintained even after the set button 16 is turned off. Since contact 17c remains off,
The lamp 18 remains off. Unless a particular abnormality occurs, when the B contact of each relay in the contact group is turned off, the A contact of that relay is turned on, so the off-delay timer 15 will not be turned off. There is a slight time lag between turning off the B contact and turning on the A contact, but since it is an off delay, there is no possibility that the timer 15 will turn off during normal operation. If a failure occurs in one of the relay pairs, e.g. press clutch 2
If one relay 20 remains on when both 0 and 21 should be off, the a contact 20x
is on, the a contact 21x is off, the b contact 20y is off, and the b contact 21y is on, and the voltage supply to the off-delay timer 15 is cut off. Therefore, the timer 15 times up and the contact 15a turns off. In other words, abnormal relay 17
is turned off, the contact 17a is turned off, each relay 20, 21, 24, 25 is turned off, the press operation enable lamp 27 is turned off, the lamp 18 is turned on to notify the occurrence of an abnormality, and the operation is brought to an emergency stop. .

It will be easily understood that the test button 18 can also be used to forcibly time up the off-delay timer 15 and cause an emergency stop.

As mentioned above, the off-delay timer 15 is
Since this is to correct the time difference between the a contact and the b contact due to the on/off of each relay, it does not require a very long time, and about 0.5 seconds is sufficient.

As described above, according to the present invention, when one of the relays used as a set for safety in the press operation control system fails, it can be detected and an emergency stop can be performed, thereby further increasing safety. becomes possible.

In this case, the present invention only uses the contacts of the relays that are actually used, and does not require any special parts other than the off-delay timer, so it can be made inexpensive.

In addition, its circuit configuration is simple, making it easy to add relays, easy to maintain and manage, and also has the effect of being able to check the safety circuit just by operating the test button. .

[Brief explanation of drawings]

The figure is a circuit diagram of an embodiment of the present invention. 5, 6... Fixed position stop relay, 24, 25...
Restart prevention relay, 9, 10... Safety-stroke relay, 15... Off-delay timer, 13, 14
...Restart prevention relay, 17...Abnormal relay, 2
0,21...Pres clutch relay.

Claims (1)

[Claims] 1 A clutch relay that operates the press clutch, a position stop relay operated by a position stop rotary cam switch, a safety-stroke relay operated by a safety-stroke rotary cam switch, and a restart prevention rotary cam switch. In the operation circuit of a press that has a relay such as an operating restart prevention relay, each of the above-mentioned relays is configured with a pair of two relays, and the a contact and b contact of these relays are connected in series, respectively. Both series circuits are connected in parallel to form parallel circuits corresponding to the pair of relays, and these parallel circuits are connected in series to form a switch group, and this switch group can also be manually turned on and off.
A safe operation circuit for a press, characterized in that an off-delay timer is connected to a power source through a series circuit of a test button that is turned off, and a contact point of the off-delay timer is connected to an emergency stop circuit.