JPS6330119B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a double-drop prevention device for a press machine.

[Conventional technology]

When the safe single stroke is selected as the operating mode of the press, a restart prevention circuit is installed to ensure that the press stops once at the fixed stop position (generally near top dead center) and starts after pressing the operation button again. It is well known that the press control circuit is provided in the press control circuit. To explain more specifically, in one safety stroke operation, the clutch brake solenoid valve for press operation is energized via the rotary cam contact for stopping in a fixed position, and the rotary cam contact for stopping in a fixed position is activated at a fixed position (e.g. , crank angle in the range of 330° to 5°) to stop the press device at a fixed position. Incidentally, in this specification, the angle means the crank angle unless otherwise specified. Further, the rotary cam contact for preventing restart is activated at an appropriate timing (for example, in the range of 270° to 300°) after passing the bottom dead center, and the self-holding is released. The restart prevention circuit is set to a self-holding state as a condition for starting the press equipment, and the restart prevention circuit is set to a self-holding state once the press start operation button is released. It is associated in such a way that Therefore, if the press control circuit as described above is operating normally, in safe one-stroke operation, when the press stops at a fixed position, release the operation button once, and then press the operation button again. The press is activated only at this time, so that the press does not overrun top dead center and cause a so-called double drop.

[Problems to be solved by the invention]

Conventional safety measures using restart prevention circuits such as those described above can avoid the danger of double dropping if each part of the press equipment is operating normally, but it can prevent welding of various rotary cam contacts. It goes without saying that if the press device falls into a state where it cannot operate normally due to such reasons, double dropping cannot be prevented. Therefore, the emergence of a double-drop prevention device that can reliably prevent double-drops even when a press equipment malfunctions, and especially the emergence of a double-drop prevention device that can be easily installed on existing press equipment. was desired.

[Means to solve the problem]

The present invention has been made in view of the current situation, and it is an object of the present invention to provide a double-drop prevention device for a press machine that can reliably prevent double-drop even in the event of a failure. The double-drop prevention device for a press machine of the present invention is intended to be easily installed on an existing press machine, and is therefore equipped with a rotary cam contact for preventing restarting and a rotary cam for stopping at a fixed position. This is realized by adding some circuit elements as described below to the premise of a conventional press control circuit equipped with contacts, a restart prevention circuit, etc. That is, the double-drop prevention device for a press machine of the present invention comprises: a clutch brake that is electromagnetically driven and transmits the rotation of the flywheel to the crankshaft; a press operation circuit for supplying power to the solenoid valve of the clutch brake; An operation button that is one of the conditions for putting the press operation circuit into operation: A fixed position stop button that operates just before top dead center and stops the press operation circuit during safe one-stroke operation. Rotary cam: A restart prevention rotary cam that operates after passing the bottom dead center but before reaching the top dead center: During safe one-stroke operation, the self-holding is released by the restart prevention rotary cam operating. and a restart prevention circuit that enters a self-holding state on the condition that the press operation button is in a stopped state. Applicable to press equipment that has a press control circuit, which is one of the conditions for achieving this: A proximity switch for detecting marks provided corresponding to the timing immediately before top dead center and the timing immediately after top dead center. and: a first output relay for stopping the solenoid valve of the clutch brake; and:
The second step is to stop the main power supply of the press equipment.
output relay: counts the output pulses of the proximity switch, and when the counted value reaches 3, the output relay of the first
a double-drop detection circuit having an output relay and a first counter means for activating the second output relay; and a first storage means for storing that the self-holding of the restart prevention circuit has been released. Then, the rotary cam for stopping at the fixed position detects the top dead center,
and a second storage means for storing that the operation button is in a stopped state and the press operation circuit is in a stopped state, and the memory content of the first storage means is logically true. If the stored content of the second storage means is logically true, the operation button is activated, and the press operation circuit is activated, the first counter means and clear the first
a double fall selection circuit having a gate group for clearing the first counter means for each press stroke when the stored content of the storage means is logically false; and: counting the output of the restart prevention rotary cam. A second counter means activates the second output relay when the counted value reaches 2, and counts the output of the proximity switch until the counted value reaches 3.
a third counter means for activating the second output relay when the count value of the second counter means reaches 1; means for clearing the third counter means when the count value of the second counter means reaches 1; and means for clearing the second counter means when the count value of the means reaches 2;
and a timer means activated by a signal for activating the second output relay, the first output relay and the first output relay being activated before the set time of the timer means elapses after the timer means is activated. and an output relay disconnection failure detection circuit that restarts the first output relay and the second output relay when none of the contacts interlocked with each of the two output relays is activated. There is. .

[Effect]

That is, in the present invention as well, during safe one-stroke operation, the press device basically stops at the top dead center for each press stroke due to the action of the restart prevention circuit on the press control circuit side. The proximity switch detects the detection mark at the timing before and after the top dead center, and the first counter means counts the output of the proximity switch, so the first counter means counts two for each press stroke. During safe one-stroke operation, the memory contents of the first memory means become true due to the operation of the restart prevention circuit, and when the press device stops at top dead center, the memory contents of the second memory means become true, so that when the press device stops at top dead center, the memory contents of the second memory means become true. Since the first counter means is cleared when a normal press starting operation is performed after the press stops, the count value of the first counter means does not normally reach three. However, when the press device overruns the top dead center, the output of the proximity switch is counted without clearing the first counter means, so the count value of the first counter means reaches 3, and the first and second counter means The output relay is activated and an emergency stop operation is performed. Furthermore, in this embodiment, if a failure occurs in the proximity switch or the restart prevention rotary cam, overrun detection becomes impossible; however, abnormalities in the restart prevention rotary cam and the proximity switch are mutually detected, and these Prevent accidents caused by malfunctions. That is, the proximity switch is activated twice for each stroke, and the anti-restart rotary cam is activated once for each stroke. Therefore, the output of the restart prevention switch is counted by the second counter means, the output of the proximity switch is counted by the third counter means, and when the count value of the second counter means reaches 1, the third counter means counts the output of the proximity switch. If the second counter means is cleared when the count value of the third counter means reaches 2, the count value of the second counter means will not reach 2 unless there is an abnormality in the proximity switch. Unless there is an abnormality in the restart prevention rotary cam, the count value of the third counter means will not reach 3. Therefore, when the count value of the second counter means reaches 2 and the count value of the third counter means reaches 3, the second output relay is activated to perform an emergency stop operation. It is possible to prevent a situation in which the detection operation becomes impossible. Further, the timer means is activated by a signal that activates the second output relay, and if the output relay is normal, at least the contact corresponding to the second output relay is activated before the set time of the timer means has elapsed. . If neither the first output relay nor the second output relay operates even after the set time of the timer means has elapsed, the first output relay and the second output relay are activated again. Even if one of at least two series of output relays fails, as long as the other output relay is normal, the emergency stop operation will be performed reliably.

【Example】

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 2 is a block diagram showing the principle of the relationship between the double-drop prevention device of the present invention and a known press control circuit. FIG. 4 is a circuit diagram specifically showing the interface between the double-drop prevention device of the present invention and a known press control circuit. First, circuit elements included in a known press control circuit will be explained. In FIGS. 2 and 4, reference numeral 1 indicates the B contact of the rotary cam for preventing restart, which falls into a valley between 270° and 300°, and the B contact 1 is made in the above angle range. Further, 2 is the A contact of the operation button, 3 is the A contact of the press operation circuit 15 that supplies power to the solenoid valve 91 for the clutch brake, and the A contact 3 is energized when the operation button 2 is engaged. It works in conjunction with a relay coil that cannot be shown. That is, one of the conditions for putting the press operation circuit 15 into operation is that the operation button 2 is turned on. Further, 4 is a well-known restart prevention circuit, in which the rotary cam for preventing restart falls into the valley during safe one-stroke operation, and is connected to the B contact 1 for preventing restart described above. When the A contact breaks, the self-holding of the relay R4 is released, and in conjunction with the break of the A contact 2 of the operation button described above, the B contact R2 and A contact R3 in the restart prevention circuit 4 are made. Relay R4 enters a self-holding state. The A contact (not shown) that is linked to this relay R4 is AND-connected to the A contact 2 of the operation button.
Therefore, relay R4 being in the self-holding state is also one of the conditions for putting the press operation circuit 15 into the operating state. Furthermore, 5 is the B contact of the rotary cam for fixed position stopping that falls into the valley in the range of 330° to 5°;
is made in the above angle range. During safe one-stroke operation, the press operation circuit 1 is connected to the press operation circuit 1 via the A contact (not shown) paired with the B contact 5 for stopping at a fixed position.
5 is supplied with power, and when the rotary cam for stopping at a fixed position falls into a valley, the press operation circuit 15 is cut off. Incidentally, all of the above-mentioned circuit elements are included in the conventionally well-known press control circuit 20. Also, 6 is the B contact of output relay DR1 for emergency stop, and 7 is output relay DR2 for main power cutoff.
This is the B contact point. Next, 8 is a crankshaft (or a member having the same rotation angle as the crankshaft), and the crankshaft 8 has a proximity switch 9 located before and after the top dead center (for example, at a 30° point and a 330° point). Detection marks 10 and 11 that are detected by are fixed. Further, 12 indicates a reset switch for resetting the double-drop prevention device of this embodiment, and 13 indicates a test switch for testing the operation of the double-drop prevention device of this embodiment. And the above elements are AC/DC converter C1
~ C7 and an input interface 30 including DC/DC converters C8 and C9, and are connected to the main circuit 40 of the double-drop prevention device of the present invention. In addition, AC/DC converters C1 to C7 and DC/
Although various types of circuits can be used for the DC converters C8 and C9, one example is shown in FIG. The structure and action will be briefly described. First, the AC/DC converters C1 to C7 have the same configuration and include a rectifier circuit using a diode bridge and a photocoupler. Taking AC/DC converter C1 as an example, if B contact 1 is closed, the output stage photocoupler becomes conductive and terminal D38 becomes L.
On the other hand, if the B contact 1 breaks, the photocoupler is cut off and the terminal D38 becomes H level. As described above, it should be noted that in this embodiment, the states of the contacts on the input side (that is, the states of the contacts in the press control device 20) are logically inverted by the AC/DC converters C1 to C7. Further, the DC/DC converters C8 and C9 have a noise removal circuit and a photocoupler. In the DC/DC converter C8, when either B contact 6 or 7 is made and the terminal D24 becomes L level, the photocoupler at the output stage becomes conductive and the terminal D26 becomes L level. Similarly, in the DC/DC converter C9, when the proximity sensor 9 is activated and the terminal D23 becomes L level, the photocoupler at the output stage becomes conductive and the terminal D22 becomes L level. The basic principle of the double-drop prevention device of the present invention is to count the output of the proximity switch 9 and clear the above counted value each time the press device stops at the top dead center. If the output of the proximity switch 9 is further counted without delay, it is assumed that the top dead center has been overrun and an emergency stop operation is performed. More specifically, when the crankshaft 8 rotates from the top dead center position, the proximity switch 9
detects the detection mark 11, and when the angle is 330 degrees, the proximity switch 9 detects the detection mark 10, and then reaches the top dead center. Therefore, the proximity switch 9 operates twice per press stroke, so if the condition for clearing the above count is that the press device has stopped reliably at the top dead center, then the above count is “0”,
The values of "1" and "2" are sequentially shown, and the above-mentioned count value never reaches "3". However, if the top dead center is overrun for some reason, the above counted value will not be cleared, so if the proximity switch 9 detects the detection mark 11 at the timing of overrunning the top dead center by 30 degrees, the above counted value will be " 3” reached. Therefore, in the present invention, when the count value reaches "3", it is determined that an overrun has occurred and an emergency stop operation is performed. In FIG. 2, the double drop detection circuit 50 is a circuit including a counter means for counting the output of the proximity switch 9, and the count value of the counter means is "3".
This is a circuit that generates a double drop detection signal S1 when the voltage reaches this point. This double drop detection signal S1 is amplified by the power drive circuit PD1 and output relay DR for emergency stop.
Demagnetize 1. Figure 4 shows the power drive circuit PD
1 shows an example of the circuit configuration, which includes, for example, a CR circuit for noise removal, a photocoupler, and an output transistor. To briefly explain its operation, the terminal D
27 becomes H level, the photocoupler and output transistor are cut off, and the output relay DR1 is demagnetized. The A contact 14 interlocked with the output relay DR1 is connected to the clutch brake 91 in the press operation circuit 15.
The clutch brake 91 is actuated by the break of the A contact 14 to bring the press to an emergency stop. In FIG. 2, the press operation circuit 15 is also shown in the output stage in order to clarify the input side and the output side, but the press operation circuit 15 is included in the press control circuit 20 and is not included in the output stage. The A contact 3 shown in the press operation circuit 15 described in the column means the A contact 3 already described in the press control circuit 20. Next, the double-drop detection signal S1 generated by the double-drop detection circuit 50 is transmitted to the OR gate 92 (here, the OR gate 92 means that it operates as an OR gate in a theoretical sense, as shown in FIGS. 5 and 6, which will be described later). In the example circuit shown in , a NAND gate is used because the input side is configured with negative logic and the output side is configured with positive logic. Demagnetize output relay DR2 for The A contact 16 interlocked with the output relay DR2 is AND-connected to the main power circuit 17 of the press control circuit 20, and when the A contact 16 breaks, the press apparatus is brought to an emergency stop by cutting off the power supply. Next, the double-drop selection circuit 60 selects the double-drop detection circuit 50 when it is confirmed that (1) in safe one-stroke operation, the press device has surely stopped at the top dead center.
Clear signal to clear the counter means in
In addition to generating CL, (2) In continuous operation or inching operation other than safe one-stroke operation, even if the press device does not stop at top dead center, the counter means in the double drop detection circuit 50 is activated every stroke. This is a circuit for generating a clear signal CL to clear the CL. As described above, the present invention performs an emergency stop operation when the count value of the proximity switch 9 reaches "3", assuming that the top dead center has been overrun. Therefore, in this embodiment, in the safe one-stroke operation where a top dead center stop is required, a clear signal CL is generated when the press device has definitely stopped at the top dead center, and when the press device is not required to stop at the top dead center, the clear signal CL is generated. During operation or continuous operation, the double-fall selection circuit 60 is configured to generate a clear signal CL every press stroke. An example of the circuit configuration will be described later, but the double-drop selection circuit 60 includes the state of the operation button 2 and the A contact 3 of the press operation circuit 15.
, the state of the restart prevention circuit 4, and the state of the B contact 5 of the rotary cam for fixed position stopping are input. In the double-drop prevention device of the present invention, it is a prerequisite for detecting an overrun that the proximity switch 9 and the rotary cam for preventing restart are operating normally. Therefore, in the present invention, the output of the proximity switch 9 and the output of the B contact 1 of the rotary cam for preventing restart are input to the self-check circuit 70, and the proximity switch 9
The operating state of the B contact 1 is compared with the operating state of the B contact 1, and if an abnormality occurs in any of the switches, a stop signal S2 is applied to the OR gate 92, and the output relay DR2 for cutting off the main power is activated. It is designed to perform an emergency stop operation. In addition, in this embodiment, two lines of output relays are provided for performing emergency stop operation, and output relays DR1,
The states of corresponding contacts 6 and 7 of output relays DR1 and DR2 are monitored to ensure that an emergency stop operation is performed even if the corresponding contacts of DR2 do not operate due to welding or the like. More specifically, output relay open failure detection circuit 8
0 is provided with timer means, which is activated by the output of OR gate 92. If contacts 6 and 7 do not operate before the timer means times up, output relay DR1,
Start DR2 again. Next, FIG. 5 is an embodiment circuit showing a more specific circuit configuration of the main circuit 40 of the double-drop prevention device of the present invention. Since the circuit shown in Figure 5 is a very specific product circuit, the basic principles of the invention, such as circuit elements for removing noise in input signals and circuit elements for adjusting the fan-out number of each gate, can be used. contains many circuit elements that are not directly involved, making it somewhat complicated for the purpose of understanding the basic principles of the invention. Therefore, the circuit diagram in Figure 6 is the circuit diagram in Figure 6 that has been organized by removing the circuit elements that are not particularly related to the basic principle of the invention in the circuit in Figure 5. is attached. Further, in FIGS. 5 and 6, the state of connection with the press control circuit 20 is shown with the same terminal numerals as in FIGS. 2 and 4. In the drawing, an inverter 51, JK type flip-flops 52, 53, and a NAND gate 5 are shown.
4, 55, an AND gate 56, and an SR type flip-flop 57 are the double drop detection circuit 5 in FIG.
0 circuit element. Incidentally, the AND gate 56 shown virtually by a dotted line in FIG. 6 among these circuit elements is the flip-flop 5 in FIG.
7 input (flip-flop 57 input is 2
It is used as an input. ), but since the input side of the flip-flop 57 is negative logic, it is expressed as an AND gate. Also, an inverter 51, a flip-flop 52,
53, NAND gates 54 and 55 are proximity switches 9
Counter means for counting the number of operations (first counter means in the claims)
When the output pulse of the proximity switch 9 applied from the terminal D25 is counted three times in a row, the output of the NAND gate 55 becomes L level and the flip-flop 57 is set, but the press device does not operate normally. As long as the output from the proximity switch 9 is counted twice and before it is counted three times, the flip-flops 52 and 53 are cleared, so the flip-flop 57 is not set. The Q output of flip-flop 57 is connected to terminal D27, and the Q output of flip-flop 57 is connected to terminal D27.
7 is set and the terminal D27 goes to H level, the output relay DR1 mentioned above is demagnetized. Further, the Q output of the flip-flop 57 is applied to the NAND gate 92a via the inverter 58.
The output of NAND gate 92 is connected to terminal D28, and flip-flop 57 is set to
When the output of the NAND gate 92a becomes H level,
The previously mentioned output relay DR2 is demagnetized via the terminal D28. Note that the NAND gate 92a corresponds to the OR gate 92 in FIG. 2, and acts as an OR gate in a logical sense, but in FIGS. 5 and 6, the input side of the gate is negative logic and the output side is positive logic. Therefore, as described above, the NAND gate 92a is used as an OR gate. Next, inverters 61, 62, 63, 64, 6
5, 66, NAND gate 68, 69, 610, AND gate 611, 612, 613, 614, 6
15, 616, OR gate 617, one shot circuit 618, 61 that generates negative pulses
9. SR type flip-flop 620, 62
1, 622, 623, and 624 constitute a double-drop selection circuit. The AND gate 611 shown virtually by a dotted line in FIG. 6 among these circuit elements is generated equivalently at the input of the flip-flop 620 in FIG. 5 (the input of the flip-flop 620 is two inputs). Although it is a logical sum, since the input side of the flip-flop 620 is negative logic,
It is shown as a virtual AND gate. First, the flip-flop 624 is for storing whether or not the operation mode on the press side is safe one-stroke operation (the first one in the claims).
storage means). The output of the restart prevention circuit 4 is applied to the flip-flop 624 from the terminal D20 via the inverter 64. During safe one-stroke operation, the restart prevention circuit 4 is released from self-holding in conjunction with the activation of the restart prevention rotary cam at a timing of 270 degrees, so the rotation angle becomes 270 degrees during safe one-stroke operation. At the timing, input terminal D20 becomes H level,
The output of inverter 64 goes to L level and flip-flop 624 is set. When the Q output of flip-flop 624 becomes H level, AND gate 614 is selected. Also, since the output of flip-flop 624 is applied to AND gates 615 and 616 via inverter 66, AND gates 615 and 616 are selected when flip-flop 624 is reset (i.e., at times other than the safety step). be done. Flip-flop 62 in AND gate 614
A Q output of 2 is also added. The flip-flop 622 is for storing that the press apparatus has surely stopped at the top dead center during safe one-stroke operation (second storage means in the claims). In this example, (1) the rotary cam for stopping at a fixed position is down in the valley (that is, between 330° and 5°), (2) the operation button 2 is released,
(3) The press operation circuit 15 is cut off.
When the conditions are satisfied at the same time, it is determined that the press device has definitely stopped at the top dead center. NAND gate 69 connected to the input of flip-flop 622 (flip-flop 622
Since the input is negative logic, the NAND gate 69 functions in a logical sense as an AND gate with the input being positive logic and the output being negative logic. ) has (1)
The output of the B contact 5 of the rotary cam for fixed position stopping is connected via the terminal D17 and the inverter 61, (2) the output of the operation button 2 is connected via the terminal D18, and (3) the press operation circuit 15 is connected to the clutch brake 91. The outputs of are connected to each other via terminal D19,
When the above three conditions are satisfied simultaneously, the output of NAND gate 69 goes to L level and flip-flop 622 is set. Note that the NAND gate 69 receives a clear signal generated by the one-shot circuit 619.
A CL (negative pulse) is also added, and this is for prohibiting the input of the flip-flop 622 and the input from becoming L level at the same time when the flip-flop 622 is reset. Furthermore, the AND gate 614 has an AND gate 6
12 outputs are applied to the AND gate 612, the output of the operation button 2 input from the terminal D18 is applied via the inverter 65, and the output of the press operation circuit 15 input from the terminal D19 is applied to the inverter 63. The output of flip-flop 620 is added via inverter 62. In addition, flip-flop 620
is to remember that the top dead center has been reached, and the flip-flop 6 is activated by the negative pulse generated by the one-shot circuit 618 at the down edge of the output of the NAND gate 68 when it reaches 330 degrees.
20 is set. Therefore, after the output of the AND gate 612 reaches the top dead center and the flip-flop 620 is set, the operation button 2 is closed and the terminal D18 becomes L level, and the press operation circuit 15 is conductive and the terminal D19 is set. becomes H level when becomes L level. Therefore, the output of the AND gate 614 is determined by pressing the operation button again when the flip-flop 624 has been set by the safe one-stroke operation and the press has surely stopped at the top dead center and the flip-flop 622 has been set. It goes to H level only when 2 is pressed and the press device is restarted normally. The output of AND gate 614 is OR gate 617
to the one-shot circuit 619 via the one-shot circuit 619.
The one-shot circuit 619 has a time constant circuit as shown in FIG. 5, and when the output of the OR gate 617 is inverted from L level to H level, the time required for the capacitor constituting the time constant circuit to reach L level is Generates a negative pulse with pulse width,
This pulse becomes the clear signal CL. The flip-flop 5 constitutes a counter means for counting the output of the proximity switch 9 based on the clear signal generated by the one-shot circuit 619.
2,53 are cleared. Also, the AND gate 615 activates the one-shot circuit 619 when the top dead center position is reached during continuous operation.
This is a circuit for starting the AND gate 61
5 includes a flip-flop 62 in addition to the output of the inverter 66 and the output of the inverter 62 described above.
3 outputs are added. The output of the NAND gate 610 is added to the input of the flip-flop 623, and the output of the B contact 5 of the rotary cam for fixed position stopping inputted from the terminal D17 is input to the NAND gate 610 via the inverter 61. ) The output of the operation button 2 inputted from the terminal D18 is outputted from the inverter 63. (3) The output of the press operation circuit 15 inputted from the terminal D19 is
Therefore, the flip-flop 623 is set when the top dead center position is reached in continuous operation. Therefore, each time the top dead center position is reached during continuous operation, the output of the AND gate 615 becomes H level, and the output of the OR gate 617 also becomes H level, triggering the one shot circuit 619 to generate the clear signal CL. Also, the AND gate 616 activates the one shot circuit 61 when the top dead center position is passed during inching operation.
This is a circuit for starting up the AND gate 6.
16, the output of the inverter 66 and the output of the AND gate 612 are added. Since the inverter 66 and the AND gate 612 operate as described above, the output of the AND gate 616 becomes H level when the operation button 2 is closed at the top dead center position during inching operation and the press operation circuit 15 is activated. , which triggers the one-shot circuit 619 via the OR gate 617. Next, in FIGS. 5 and 6, inverters 71, 72, NAND gates 73, 74, 75, one-shot circuits 76, 77, and JK type flip-flops 78, 79, 710, 711 are replaced by the self-check circuit 70 of FIG. Among them, a counter means (second counter means in the claims) constituted by flip-flops 78 and 79 checks for a defect in the proximity switch 9, and flip-flops 710 and 79
711 and a NAND gate 75 (the third counter means in the claims), a failure of the restart prevention rotary cam is checked. First, the flip-flop 78 outputs J.
Since the Q output is fed back to the K input, it is inverted at the timing of the down edge of the output of the inverter 71. (That is, it acts as a T-type flip-flop.) Also,
Since the flip-flop 79 has its J input fixed at H level and its K input fixed at L level,
Set on the down edge of the Q output of flip-flop 78. Then, the B contact 1 of the rotary cam for preventing restart is connected to the inverter 71 from the terminal D38.
Therefore, when the output pulse of the B contact 1 of the restart prevention rotary cam is applied twice in succession, the output of the flip-flop 79 becomes H.
However, as long as the proximity switch 9 is operating normally, the flip-flops 78 and 79 are cleared by the pulse generated by the one-shot circuit 76 before the flip-flop 79 is set. Not announced. Since the output of the flip-flop 79 is applied to the NAND gate 92a, when the flip-flop 79 is set due to an accident such as welding of the proximity switch 9, the output of the NAND gate 92a goes to H level and is passed through the terminal D28. The output relay DR2 of is demagnetized. Flip-flop 710 is then wired similarly to flip-flop 78, and flip-flop 710 is wired similarly to flip-flop 78.
11 is wired in the same way as flip-flop 79, so that when the output of proximity switch 9 is applied twice in succession, flip-flop 711 is set. Since the Q output of flip-flop 711 and the Q output of flip-flop 710 are applied to NAND gate 75, after flip-flop 711 is set, the output of proximity switch 9 is applied to flip-flop 710, and flip-flop 710 is set. Then,
The output of the NAND gate 75 goes to the L level, but as long as the B contact 1 of the rotary cam for preventing restart is operating normally, the flip-flops 710 and 711 close before the output of the NAND gate 75 goes to the L level.
is cleared by the pulse generated by the one-shot circuit 77, so the output of the NAND gate 75 does not go to L level. The output of the NAND gate 75 is the NAND gate 92a.
Therefore, if the output of the NAND gate 75 becomes L level due to an accident such as welding of the B contact 1 of the rotary cam for preventing restart, the output of the NAND gate 92a becomes H level and the signal is The aforementioned output relay DR2 is demagnetized. Next, a timer 81, a NAND gate 82, an SR type flip-flop 83, and an AND gate 8
4 constitutes an output relay open failure detection circuit. In FIG. 6, an AND gate 84 virtually indicated by a dotted line indicates the logical sum of negative logic equivalently generated at the S input of the flip-flop 83. That is, B contact 6 of output relays DR1 and DR2,
7 is connected to one input of the NAND gate 82 and the input of the flip-flop 83 via the terminal D26, and when either B contact 6 or 7 is made as output relays DR1 and DR2 are demagnetized, the terminal D26 goes to L level. , and prohibits the output of the NAND gate 82 from going low. Further, the timer 81 is composed of a time constant circuit and a switching transistor as shown in Fig. 5. When the input of the time constant circuit becomes H level, the switching transistor is cut off after a set time has elapsed, and the output becomes H level. become. The output of the timer 81 is connected to the other input of the NAND gate 82, and if the terminal D26 is at the H level when the set time of the timer 81 has elapsed (that is, the B contacts 6 and 7 are activated due to welding, etc.). Otherwise, the output of the NAND gate 82 becomes L level and the flip-flop 83 is reset. Next, the above matters and Figures 7, 8 and 9
The operation of this embodiment will be explained with reference to the time chart shown in the figure. First, during safe one-stroke operation, the clutch brake 91 of the press operation circuit 15 is energized via the A contact (the contact paired with the B contact 1 in the figure) of the rotary cam for stopping at a fixed position. When the A contact of the rotary cam for position stopping breaks in the range of 330° to 5°, braking is applied to the press device and it stops at the top dead center. In addition, the A contact of the restart prevention rotary cam (A contact paired with B contact 5 in the figure) breaks in the range of 270° to 300° to release the self-holding of the restart prevention circuit 4. . Then, the operating condition of the press operation circuit 15 is that the restart prevention circuit 4 enters the self-holding state, and the restart prevention circuit 4 enters the self-holding state on the condition that the operation button 2 is released. Therefore, in the first safety stroke, when the press device stops at the top dead center, once you release the operation button 2 and then press the operation button 2 again, the press device is activated. Now, when the press device is started, the proximity switch 9 operates at the 30° timing and the 330° timing, and the terminal D2 is connected via the AC/DC converter C9.
A reverse phase pulse is input to the flip-flop 52, which is inverted by the inverter 51 and sent to the flip-flop
applied to the trigger input. Since the flip-flop 52 functions as a T flip-flop, it is set by a pulse applied at a timing of 30° and reset by a pulse applied at a timing of 330°. (Down Edge Trigger) On the other hand, under normal conditions, the test button 13 is broken and the terminal D22 is at H level, so the output of the NAND gate 54 is the inverted version of the output of the flip-flop 52, that is, the Q of the flip-flop 52.
The format is the same as the output. Therefore, the flip-flop 53 is set using the timing at which the flip-flop 52 is reset at 330 degrees as a trigger. Now, in the safe one-stroke operation, when the temperature reaches 270 degrees, the self-holding of the restart prevention circuit 4 is released and the input terminal D20 goes to H level, and the down edge of the output of the inverter 64 that inverts this turns the flip-flop 624. is set, and the H level Q output of flip-flop 624 is applied to AND gate 614. Further, the terminal D17 is connected to the input of the NAND gate 69 via the inverter 61, and
Terminal D18, terminal D19, one shot circuit 61
9 are connected to each other. Then, the terminal D17 becomes 330 degrees and becomes the L level at the timing when the B contact 5 of the rotary cam for fixed position stop is closed, and the terminal D18 becomes the H level when the operation button 2 breaks, and the terminal D1
9 becomes H level when the A contact 3 of the press operation circuit 15 breaks (that is, when the press is stopped), and the output of the one shot circuit 619 basically becomes H level except at the pulse timing of the clear signal CL. level, the press device is at the top dead center position and the operation button is released.
Further, when the press device is stopped, the output of the NAND gate 69 becomes L level and the flip-flop 622 is set. That is, when the press device has definitely stopped at the top dead center, the flip-flop 6
22 is set. Furthermore, when the B contact 5 of the rotary cam for stopping at a fixed position is made at a timing of 330 degrees and the output of the terminal D17 becomes L level, the one shot circuit 618 is triggered via the inverter 61 and the NAND gate 68, and the one shot circuit 618 is activated. Flip-flop 620 is also set by the generated anti-phase pulse. Therefore, after the press has surely stopped at the top dead center, the terminal D18 is opened by making the A contact 2 of the operation button.
becomes the L level, the press operation circuit 15 is activated, and the terminal D19 becomes the L level, then the terminals D18,
Since D19 is connected to AND gate 612 via inverters 65 and 63, the output of AND gate 612 becomes H level. At this point, the flip-flop 62
Since both 2 and 624 are set, the output of AND gate 614 becomes H level, one shot circuit 619 is triggered via OR gate 617, and one shot circuit 619 generates a clear signal CL which is a reverse phase pulse. Since the flip-flops 52 and 53 constituting the counter means are both reset by this clear signal, the counter means counts the output pulses of the proximity switch 9 at timings of 30° and 330° from this point on. That is, the counter means constituted by flip-flops 52 and 53 is stepped at the timing of 30° and 330°, and is cleared when the top dead center stops, so that the counted value is "0", "1", "2". However, if you overrun the top dead center position for some reason, more specifically if you pass through top dead center while holding down the operation button 2, or if you overrun the top dead center position without pressing the operation button again. If the press operation circuit 15 is not cut off at the top dead center, or if the rotary cam for stopping at a fixed position does not operate, the conditions for setting the flip-flop 622 are not satisfied, so the one-shot circuit is closed. 619 is not triggered, clear signal CL
does not occur either. Therefore, in this case, the flip-flop 53 remains set as it passes through the 30° point, as shown hypothetically by the dotted line in FIG. When the temperature reaches 30 degrees, the proximity sensor 9 is activated and the terminal D25 becomes L level, and the inverter 51
Since the output of becomes H level, NAND gate 55
The output of flip-flop 57 becomes L level.
is set, and the output terminal D27 becomes H level. Further, by setting the flip-flop 57, the output of the NAND gate 92a also becomes H level, and the output terminal D28 also becomes H level. When the output terminal D27 becomes H level, the output relay DR1 is demagnetized via the power drive circuit PD1 shown in FIGS. 2 and 4, and the press operation circuit 1 is activated.
Since the A contact 14 in 5 is cut off, the clutch brake 91 is demagnetized and the press apparatus comes to an emergency stop. Moreover, when the output terminal D28 becomes H level, the second
The output relay DR2 is demagnetized via the power drive circuit PD2 shown in Fig. 4 and the main power supply circuit 1.
Since the A contact 16 in 7 is cut off, the press apparatus also comes to an emergency stop. As described above, in the present invention, in order to detect an overrun, the proximity switch 9 and the rotary cam for preventing restart must be operating normally, and in this embodiment, the self-check circuit 70 detects the proximity switch 9. The system alternately monitors for abnormalities in the rotary cam and the rotary cam used to prevent restarting. First, B contact 1 of the rotary cam for restart prevention is
Since it is made in the range of 270° to 300°, terminal D38
becomes L level in the range of 270° to 300°. Inverter 71 inverts the level of terminal D38, and flip-flop 78 inverts the level of inverter 7 at 300°.
It is set using the down edge of the output of 1 as a trigger. The output of the flip-flop 78 is inverted by the NAND gate 74, and the one-shot circuit 77 generates a reverse phase pulse using the top edge of the output of the NAND gate 74 at a timing of 300° as a trigger.
The flip-flops 710 and 711 are cleared by the reverse phase pulse generated by the one-shot circuit 77. The output of the proximity switch 9 is applied to the trigger input of the flip-flop 710 via the terminal D25, and reverse phase pulses are generated at the terminal D25 at timings of 30° and 330°. Flip-flop 710 functions as a T-flip-flop, and since the initial clear timing is 300°, flip-flop 710 is
It will be set at a timing of 330 degrees and reset at a timing of 30 degrees. Further, the flip-flop 711 is set using the down edge of the Q output of the flip-flop 710 at a timing of 30° as a trigger, and is cleared by an anti-phase pulse generated by the one-shot circuit 77 at a timing of 300°. Flip-flop 710 in NAND gate 75
However, since flip-flop 711 is set by resetting flip-flop 710, normally flip-flop 710 and flip-flop 711 are not set at the same time.
Therefore, since the output of NAND gate 75 normally remains at H level, the output of NAND gate 92 remains at L level, and no emergency stop operation is performed via output terminal D28. However, if some kind of failure occurs in the rotary cam used to prevent restarting, the terminal D3 will open at 270° to 300°, as shown hypothetically by the dotted line in Figure 8.
8 is missing, the flip-flop 78 is not set at the 300° timing, and the clearing negative phase pulse (circle A in FIG. 8) generated by the one-shot circuit 77 at the 300° timing is ) is also missing. Therefore, the flip-flop 711 remains set and passes through the 300° timing, and when the flip-flop 710 is set at the 330° timing, the output of the NAND gate 75 goes to L level, and the output of NAND gate 92a goes to H level. As described above, an emergency stop operation is performed by cutting off the main power supply. On the other hand, the output of the flip-flop 711 is inverted by the NAND gate 73 and applied to the one-shot circuit 76, and the one-shot circuit 76 is triggered by the up edge of the output of the NAND gate 73 to generate an anti-phase pulse for clearing the flip-flops 78 and 79. . That is, the one-shot circuit 76 outputs the flip-flop 7 at a timing of 30 degrees.
Clear 8,79. The flip-flop 79 is set using the down edge of the Q output of the flip-flop 78 as a trigger.
Since the set timing by the Q output of 8 and the clear timing by the output of the one-shot circuit 76 are exactly the same, as long as the proximity switch 9 is normal, the flip-flop 79 is not set and the output of the flip-flop 79 remains at the H level. Therefore, since the output of NAND gate 92a maintains the L level, no emergency stop operation is performed via output terminal D28. However, if some kind of failure occurs in the proximity switch 9, the reverse phase pulses applied to the terminal D25 at the 330° timing and the 30° timing will be lost, so the flip-flop 710, as shown hypothetically by the dotted line in FIG. 711 remains reset, and the negative phase clearing pulse (indicated by circle B in FIG. 8) generated by the one-shot circuit 76 at the 30° timing is also missing. Therefore, the flip-flop 78 is not cleared at the 30° timing, and the flip-flop 78 is not cleared at the 300° timing.
It is reset using the down edge of 1 as a trigger. When the flip-flop 78 is reset in this manner, the flip-flop 79 is set at the timing of the town edge of the Q output. (Circle C in FIG. 8) Therefore, the output of flip-flop 79 becomes L level, the output of NAND gate 92a becomes H level, and an emergency stop operation is performed by cutting off the main power supply. Further, when an emergency stop operation is performed due to a failure of the proximity switch 9, the lamp 712 lights up because the output of the inverter 72 is at the L level, and when an emergency stop operation is performed due to a failure of the restart prevention rotary cam. The lamp 713 lights up. Now, when the main power supply circuit 17 is cut off by the demagnetization of the output relay DR2 due to the output terminal D28 becoming H level, after the so-called mechanical delay time of the relay contact has elapsed, the state shown in FIGS. When B contact 7 is made, the photocoupler in the output stage of DC/DC converter C8 is turned on, so that the terminal D26 becomes L level. Therefore, even if the output of the timer 81 goes to the H level after the delay time set by the timer 81 has elapsed after the output of the NAND gate 92a goes to the H level, the output of the NAND gate 82 remains at the H level. Yes, the flip-flop 83 remains set. However, if the contact linked to the output relay DR2 is welded, the B contact 7 remains broken, so the terminal D26 remains at the H level as shown hypothetically by the dotted line in FIG. Therefore, when the output of timer 81 goes high, the output of NAND gate 82 goes low and resets flip-flop 83. By resetting the flip-flop 83, the flip-flop 57 is set, and the terminal D27 is set to H level, and the clutch brake 91 in the press operation circuit 15 is operated to perform an emergency stop operation. In the above explanation of the operation, only the case of safe one-stroke operation was explained, but in the case of continuous operation, the output of the AND gate 615 becomes H level at the timing of top dead center, the one shot circuit 619 is triggered, and In the case of inching operation, if the operation button 2 is set at the timing of top dead center, the output of the AND gate 616 becomes H level, the one-shot circuit 619 is triggered, and the flip-flops 52 and 53 are cleared. Also, the clear signal CL generated by the one-shot circuit 619 is sent to the flip-flops 620, 621, 6.
Also used to initialize 22,623,624.

【effect】

As explained above, according to the present invention, if the top dead center is overrun for some reason during safe one-stroke operation, an emergency stop operation is performed before the angle reaches a dangerous angle, so that the so-called so-called press equipment This will prevent you from falling twice. In addition, in the present invention, if an abnormality occurs in the elements that must operate normally in order to detect an overrun, that is, the proximity switch and the rotary cam for preventing restart, regardless of whether an overrun actually occurs or not. Since the emergency stop operation is performed, safety can be ensured even if the double-drop prevention device itself breaks down. In addition, in the present invention, two output relays are used for emergency stop.
A series is provided, and if the output relay of one series does not respond within a certain period of time, the output relay of the other series is activated, so safety can be ensured in this respect as well against failure of the double-drop prevention device itself. . Furthermore, the double-drop prevention device of the present invention requires only a new proximity switch to be added as an element for obtaining signals from the press equipment, and the existing press control circuit is used as an input source for other signals. Since all the contacts are used, it can be easily attached to existing press equipment.

[Brief explanation of the drawing]

Figure 1 is a principle diagram of the double-drop prevention device of the present invention.
Figure 2 is a block diagram showing the relationship between the double-drop prevention device of the present invention and a known press control circuit, Figure 3 is a power supply circuit diagram used in the present invention, and Figure 4 is the double-drop prevention device of the present invention. FIG. 5 is a circuit diagram showing an embodiment of the double-drop prevention device of the present invention, and FIG. 7 is a circuit diagram showing the circuit elements directly related to the basic principle of the invention extracted from FIG. Chart, Figure 8 is Figure 5 and Figure 6
FIG. 9 is a time chart of the self-check operation in the circuit shown in the figure, and FIG. 9 is a time chart of the output relay open failure detection operation in the circuit shown in FIGS. 5 and 6. 1... B contact of rotary cam for restart prevention, 2
...Run button, 3...A contact for press operation, 4
... Restart prevention circuit, 5 ... B contact of rotary cam for fixed position stop, 6, 7 ... B contact of emergency stop output relay, 8 ... Crankshaft, 9 ... Proximity switch, 10, 11 ... Detection mark, 14...A contact of the emergency stop output relay, 15...Press operation circuit, 16...A contact of the emergency stop output relay,
17...Main power supply circuit, 20...Press control circuit,
30...Input interface, 40...Double drop prevention device, 50...Double drop detection circuit, 52,5
3...Flip-flop, 60...Double drop selection circuit, 619...One shot circuit, 622,6
24... Flip-flop, 70... Self-check circuit, 78, 79, 710, 711... Flip-flop, 76, 77... One-shot circuit, 80... Output relay open failure detection circuit, 81
...Timer, DR1, DR2...Emergency stop output relay.

Claims (1)

[Scope of Claims] 1. A clutch brake that is electromagnetically driven and transmits the rotation of the flywheel to the crankshaft, a press operation circuit for supplying power to the solenoid valve of the clutch brake, and putting the press operation circuit into operation. The operation button, which is one of the conditions for this, the rotary cam for stopping at a fixed position, which operates just before the top dead center and stops the press operation circuit during safe one-stroke operation, and the passage of the bottom dead center. The restart prevention rotary cam operates before the rear top dead center is reached, and the self-holding is released by the restart prevention rotary cam activated during safe one-stroke operation, and the press operation button is activated. and a restart prevention circuit that enters a self-holding state on the condition that it is in a stopped state, and one of the conditions for bringing the press operation circuit into an operating state is that the restart prevention circuit is in a self-holding state. A double-drop prevention device for a press device attached to a press control circuit that has been installed includes a proximity switch for detecting marks provided corresponding to the timing immediately before top dead center and the timing immediately after top dead center; a first output relay for stopping the solenoid valve of the clutch brake; a second output relay for stopping the main power source of the press; and counting output pulses of the proximity switch; When the counted value reaches 3, the double-fall detection circuit has a first counter means that activates the first output relay and the second output relay, and the self-holding of the restart prevention circuit is released. a first storage means for storing the fact that the fixed position stop rotary cam has detected the top dead center, the operation button is in the stopped state, and the press operation circuit is in the stopped state. at least a second storage means for activating the operation button, and when the storage contents of the first storage means are logically true, the storage contents of the second storage means are logically true, and the operation button clears the first counter means on the condition that the press operation circuit is in the operating state and the press operation circuit is in the operating state, and if the stored content of the first storage means is logically false; a double fall selection circuit having a gate group for clearing the first counter means for each press stroke; and counting the output of the restart prevention rotary cam, and when the counted value reaches 2, the second a second counter means for activating the output relay; and a third counter means for counting the output of the proximity switch and activating the second output relay when the counted value reaches 3.
counter means, means for clearing the third counter means when the count value of the second counter means reaches 1, and means for clearing the third counter means when the count value of the third counter means reaches 2; a self-check circuit having a means for clearing the timer means; and a timer means activated by a signal for activating the second output relay, and after the timer means is activated, the set time of the timer means is If none of the contacts interlocking with each of the first output relay and the second output relay operate before the time elapses, the first output relay and the second output relay
A double-drop prevention device for a press device, comprising at least an output relay disconnection failure detection circuit that restarts the output relay of the press device.