DE1506531B1 - CIRCUIT ARRANGEMENT FOR ELECTROMAGNETS FOR LIFTING AND CONVEYING PLATES MADE OF MAGNETIZABLE MATERIAL, IN PARTICULAR IRON PLATES - Google Patents

Description

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The invention relates to a circuit arrangement for necessary to grip the plate before so Electromagnet for lifting and conveying plates has fallen so far that the magnet is unable to made of magnetizable material, especially iron - to attract them again, it has been found necessary, with the current for the winding of the or directed, electronically controlled rectifier to the Einder Magnet is briefly interrupted to the 5 and switching off the current for the magnet winding to use the upper plate from under this sticking further.

Disks to be released, then switched on permanently, so that the times for switching on and off

around the upper plate when conveying to determine the current for the magnet with great accuracy

and can be determined at this location again, even if the period is switched to release the plate. io fractions between such switching on and off

Arrangements of the above-mentioned type are amounts to seconds, is according to a further development knows. They have the disadvantage that the length of the invention provided that the magnet winding short-term interruption of the strength, the measurements via the electronic control unit to a trigger and the weight of the plates very precisely adapted to the circuit for a controlled rectifier unit got to. Also, it is difficult to get plates from -15 closed. The arrangement can be so close to one another to solve that by water that is hit between the that across the input terminals Plates squeezed and under certain circumstances a diode is built into the lifting magnet or the ice, is frozen, clinging to each other. Attempts have been made to connect these to the primary winding of a transformer in Avoid disadvantage by having special pole pieces connected in series, the secondary winding of which is connected to it Has used lifting magnets that cause 20 outside terminals to connect to input terminals of the control unit magnetic field does not penetrate so deeply into the plates. unit are connected.

But this measure also requires consideration. A voltage pulse is thereby generated via the

take on the plate thickness. Transformer transferred to the control unit when

The object of the invention is to provide a circuit that interrupts the current in the magnet winding, arrangement of the aforementioned type to 25 and the resulting from this power interruption

create at which the short-term interruption of the overvoltages are significantly reduced since

Excitation current does not need to be adapted. through the diode and the low-impedance primary

This task is compensated according to the invention by winding the transformer,

solved that in the case of the short-term current- In a further development of this embodiment Interruption caused releasing the plate a result of the arrangement according to the invention contains the control

the remanence of the plate and the lifting magnet in the unit one with an electronic output relay

Magnetic winding induced voltage pulse of an adjustable time measuring unit provided, the input of which

electronic control unit is supplied, which is based on a flip-flop unit with an on the yoke of the

connected to the magnet for a predetermined short period of time

The current for the magnet winding is switched on again by 35 and is mechanically controlled in such a way that the contact

to hold the top plate permanently. is closed when the yoke is on the surface of a

In the arrangement according to the invention, the stack of plates rests, the output relay switching the current on again for the magnets, the timing unit to the flip-flop unit, having the greatest influence on the upper, the magnet on the closed, that this is after a certain plate lying next which is therefore more restrained from moving downward at 40 period Th in which the yoke moves upward than that is reset.

The rest of the plates, whose inertia helps to keep them from moving

the top plate to release. Experience has shown that the interruption of the sensor contact is fixed

that even with very different panels - the required piece can be lifted out a further piece

strengths and weights a satisfactory solution 45 will be achieved by regulating the period Th so

achieved when the period of tea can vary sufficiently briefly that the plate or the plate stack

will hold, so that it is possible to un- a certain free fall height, z. B. 20 to 30 cm,

in danger of seizing the moment she receives

is about to fall. In a further development of this embodiment

According to a further development of the invention, the output of the stevedoring unit is connected to a second point in time Tin the current for the magnetic winding flip-flop unit after a previously fixed relay of the first time measuring unit, at one output of which it is switched on again, after which through the remanence one is connected in an amplifier with a contactor again, the effect of induced voltage pulse is formed whose disconnecting contacts to the power supply and the control unit is supplied, which are connected to the 55 for the motor of the elevator in series fixed short period tea again the current, whereby it is achieved that the motor of the lifting is interrupted, and this process is automatically switched off in the factory at the end of the period Th , a predetermined number of times is repeated. This allows the other output of the second flip to ensure that all plates with the exception of the flop unit have fallen down with one input of a control officer before the magnet 60 amplifier is connected, the output terminal of which moves to the destination of the upper plate because of the Trigger circuit is connected, and the second the plates due to their inertial mass several times. Period Tu a from the mentioned relay to the mentioned sticking step by step and finally canceled, but the upper control plate, which is fed to the input of the control amplifier, locks after each mechanical loading, blows are securely held. This ensures that the controlled equalization

In order to generate the short periods of time Tre , which the erector sets his ignition pulses and the current for

3 4

interrupts the lifting magnet, so that the plate- This results in the controlled rectifier

pile begins to fall. after the specified period of time Tin den

According to a further embodiment, this off current for the lifting magnet switches off again, so the implementation of the inventive arrangement is that a new voltage pulse arises in the magnet winding an input of the second flip-flop unit, and that also the third Zeitmeßdem with a is switched on again with an electronic output unit in order to control the influence of the relays provided, controllable second time measuring unit - To block. This starts a new stage of the coordinated period Tsk for switching off the control shaking and disconnecting process, which is only then finally reset the amplifier and its relay. is set when the second timing unit the

As a result, the elevator is only switched off again for an entire set shaking and separating time when the time period Tsk has expired and measured.

this period of time can be set so that it measures a shaking and separating time set in advance with reference to the drawing, is described in more detail, and specifically shows
after which only the upper plate of the lifting magnet F i g. 1 shows a circuit diagram for the power supply. unit of the system,

According to the invention, one output of FIG. 2 a circuit diagram for the electronic control second flip-flop unit via a first AND unit of such a system and
also with one with an electronic output 20 F i g. 3 shows a simplified time diagram for the third controllable time measuring unit provided by the system, which is provided with active relays.

be connected, their output relays via a line. In the drawing, 1 denotes one or more

tion so connected to a third flip-flop unit lifting magnets, which are used in a crane, not shown

is that this is reset and a second lifting and conveying loads from magnetizable

Line the opening of a second AND unit for 25 material, in particular iron plates, are attached,

a voltage pulse is prepared, which is The power supply of the lifting magnet is carried out by

Gangskkmmen of the control unit arises when a three-phase power network R, S, T via rectifier 2,

controlled rectifier is switched off. 3 and 4 with a load resistance B and Thy-

This results in a blocking of the control transistors 5, 6 and 7, the control electrodes 8 via the

Unit connected to a trigger circuit 10 during the vibrations and oscillation 3 ° resistance 9

appearances that are immediately after the interruption, which is related to the information provided by an electronic control

of the current for the lifting magnet can arise, unit set times the thyristors 5 to

to prevent the mentioned current from switching on and off at 7. The control unit 11 is over

early, but only after a period of time Tsf terminals R and O from the power supply network

is switched on. 35 takes care of and leads to the set times

In a preferred embodiment of the invention, voltages -12 V are clamped to the trigger circuit

proper arrangement are the input terminals and 0 V, after which the trigger circuit the thyristors 5,

the control unit switches on and off via a pulse amplifier and a 6 and 7 and thus the current of

electronic relay to a feed of the second rectifier 2, 3 and 4 to lifting magnet 1

AND unit connected, whereby it is achieved that 40 turns on and off.

the voltage pulse of the magnet winding the second parallel via the terminals 12 and 13 of the

And unity opens. Lifting magnet is the primary winding 15 of a trans-

In this case, the output of the second formator 14 is preferably connected through a diode 16, with

And unit by a fourth flip-flop unit with the purpose of the rectifiers 2, 3 and 4 against

one with an electronic output relay to shield 45 overvoltages that occur in the magnet

see fourth controllable timing unit connected winding arise when the current in this sub-

and the output relay is broken through one line and one, namely the diode 16 causes one

third AND unit so to the control amplifier short circuit of the overvoltages and guaranteed

concluded that the output terminal of the amplifier also that only current pulses 17 at certain

after a certain period of time Tre a trigger 50th polarity go through the primary winding 15

voltage for the controlled rectifier can be supplied. These current pulses 17 (FIG. 3) serve to

will. to activate the control unit 11, and arise when

In this way, the controlled rectifier switches the current in the lifting magnet 1 is interrupted, and

after the expiry of the period Tre the lifting magnet is indeed at this point in time if one of the lifting

again to adjust the case of the disk stack 55 magnets 1 raised, not shown disk or a

and one or more stacks of plates adhering to the top plate begins to fall due to the remanence

shake off further plates. in the iron plate or the plate stack and the

In the last-mentioned embodiment of the inventive yoke of the lifting magnet, a voltage pulse 17 in the arrangement according to the invention is preferably induced from the magnet winding. The trigger circuit 10 gang of the second AND unit through a fifth flip 60 contains a generator for pulses with a ratio-flop unit still with a with an electronic moderately high frequency, z. B. 2000 Hz, the output relay provided fifth adjustable time are capable of measuring the thyristors every half milliseconds once connected and the output relay to excite. The voltage pulse 17 of the magnet A conduit partly sets to the second input of the second winding to the time of cutoff and flip-flop unit for resetting the fifth time 65 re-turning on of the current for the magnet measuring unit after a certain period Tin, an accuracy of less as 0.5 milliseconds partly to the third flip-flop unit for the third time fixed. The interruption of the current for the magnet measuring unit connected. sets in motion a periodically repeated process, the

5 6

lasts a certain time within which all impulses 17 are generated. But there are generally several Plates with the exception of the upper ones are shaken off, lifting magnets, in practice up to z. B. twelve, ver and the top plate is finally held. will turn into a period of uncertainty

The shaking or separating process is shown in terms of time, in which the magnets, which the plate first illustrated in the time diagram (FIG. 3). Release in time 5, give rise to overvoltages. So that point r ₀ begins a lifting mechanism, not shown, in which these overvoltages are not hooked into the yoke of the lifting magnet too early, causing the lifting magnets to switch on, it is useful to lower a stack of plates, not shown. In terms of time, according to the invention in the circle of the control point I ₁ , the magnet is to be connected to the upper plate on the circuit 11, a delay circuit which is hit and causes a cone provided on the magnet yoke from a third controllable timing circuit TBL betakt 18iz Via contactors (not shown) one is available, which sets a time period Tbl in which the reversal of the current Ih for the lifting mechanism, which control amplifier ST is blocked, ie at time t ₅ . The result is that the contact 18 «is switched off. The time measuring circuit TBL consists of an electrowhen the yoke with the relay 40 fixed by the lifting magnet and a charging circuit that connects a stack of plates a little upwards 15 to the ground frame and has been lifted. This break indicates an adjustable resistor 42 includes and will follow one or more panels as it is lifted. from a third flip-flop unit 43 via an AND-Am magnet yoke, a contact 186 is also provided, unit 44 is set in motion, which with its one of the, as shown in FIG. 2, is connected between a zero input 45 via a line 46 to the second flip terminal 19 and an input terminal 20 in the 20 flop unit 27 that the AND-on control unit is attached. This standardized input terminal 44 opens when the flip-flop unit 27 in Zeitist via a series resistor 21 having a direct point t ₃ is the separation period in Tsk gear. After current terminal 22 of z. B. -12 V connected. When the time period Tbl expires, ie at time t _s , the contact 18 b is switched off at time t ₂ , the electronic relay 4J is switched off via lines 47, 48 and the voltage of the input terminal 20 25 changes to an AND adapter unit 49 the third The flip-flop suddenly went from 0 to -12 V, which caused an adjustable unit 43 to return, which set the timer unit TH in motion via a line 59 and raised a signal to the first input 51 of the second and a signal from the setting of the timer unit TH be unit 52 sends.

correct period of time, which determines how long the The control unit 11 is prepared after the

Flattenstapel is to be raised before the 30 voltage pulse 17 to detect, which is to begin shaking in the magnets of the lower plates, continues. arises when the stack of plates begins to fall, the timing unit TH, which has released via a first flip-flop after most of the lifting magnets, the upper unit 23 is switched on, consists of a plate. The secondary winding 53 of the electronic relay 24 and a charging circuit, which is made up of transformer 14, as shown at the top right in FIG. 2 shows a common to ground M and a controllable resistor 35, with its output terminals 54a, 55a to the capacitor 25 connected to 26. After the input terminals 54b, 55b of a potentiometer 55 of the period Th , the relay 24 connects the flip-flop to the control unit 11, to which a regular unit 23 returns and thus switches the timing signal taken and via a pulse amplifier 57 unit TH at the time Z ₃ off. At the same time, one and one electronic relay 58 to an input 59 other flip-flop unit 27 is excited, which via a 40 of the second AND unit 52, their third and fourth • amplifier 28 and a contactor 29, whose terminals input 60 and 61 are connected to -12 V or a first off-30, 31 with the motor of the lifting gear in series with the third AND-unit 62, are switched, the lifting movement is sent via its switch-off. When the voltage pulse 17 occurs, contacts 32 cease. In addition, a second controllable input 59 also receives a short eye-timing circuit TSK activated, which consists of an electronic view long -12 V. This voltage passes through the niche relay 33 and a charging circuit, the second AND unit 52, which now has a capacitor 34 connected to ground M at all of its units and has an active signal to output 63 which contains an adjustable resistor 35. The second AND unit, whereby a fourth and fifth flip time circuit TSK sets an entire shake-off or flop unit 64 and 65 so that the separation time Tsk , which expires at time I _1. After 50 they both for their outputs 66 or 67 -12 V er-atlauf of the irennzeit T ^ k, the flip-flop unit 27 will hold. As a result, a fourth and a fifth Zeitvcm electronic relay 33 of the time measuring circuit TSK measuring unit TRE and TIN are set in motion. The Zeitzuiixk posed. Simultaneously with the beginning of the separation measuring unit TRE, which consists of an electronic reference time, ie at time / ₃ , an input voltage lais 63 and a charging circuit with a control amplifier ST connected to ground, the minimum connected capacitor 69 and a controllable resistor are interrupted has two inputs 36, 37, of which the stand 70, determines how much ZeilTnB is connected between a 26 to the flip-flop unit 27, the voltage pulse 17 and the restart and one output of which is a terminal 38 of the lifting magnet 1 for the Setting of the case hold, which should also pass as an input terminal for the trigger movement of the plate stack. The time circuit 10 is used, while the second output to a 6a measuring unit TIN, which is connected to an electronic Re-Kontrolkmpe 39, which lights up, lais 71 and a charging circuit with a ground used the interruption of the input voltage of the tied capacitor 72 and an adjustable Control amplifier 57 "consists of a sub-resistor 73 via the input 36, determines how much time Tj χ causes the thyristors 5, 6 and 7 to break, which means that from the time of the voltage pulse 17 until the current //, for the lifting magnet 1 is switched off 65 again Turning off the lifting magnet is to pass, so that the one attracted by the lifting magnet with a subsequent voltage pulse begins to fall.

As soon as this happens, the voltage should after the period Tre, which is very short,

ζ. Β. shorter than 20 milliseconds, the electronic relay 68 resets the fourth flip-flop unit 64 via a line 74, and an activation signal is generated from the output 75 of this unit to the first input 76 of the third AND unit 62, which at time t ₆ still receives an activation signal from the fifth flip-flop unit 65 at the second input 77. The remaining inputs 78 of the third AND unit 62 are, as shown in the drawing, constantly below -12 V. At time t _G , the third and is therefore produced at the second output 79 connected to the second input 37 of the control amplifier via a line 80 -Unit 62 a signal voltage, and the trigger unit 10 is switched on via the terminals 38, whereby the control voltage for controlling the electrodes 8 of the thyristors 5, 6 and 7 is supplied via the resistor 9 and the current II for the windings of the lifting magnets 1 is switched on again.

After the period Tin has elapsed, ie at time t ₇ , the timing unit TIN resets the fifth flip-flop unit 65 via a fourth AND unit 81 and a line 82, so that the activation voltage at the second input 77 of the third AND unit 62 disappears. The output voltage at the output 79 and the voltages at the second input 37 of the control amplifier ST disappear at the same time, so that the control voltage of the terminal 38 of the trigger unit 10 disappears and the current II for the lifting magnet 1 is interrupted by the rectifiers 2, 3 and 4.

The third flip-flop unit 43 simultaneously sets the blocking period in motion again, after which the control circuit 11 is again ready to detect a new voltage pulse 17, after which the process is repeated until the entire separation period Tsk has passed. The electronic relay 33 then resets the second flip-flop unit 27, which permanently switches on the lifting magnets 1 via its output and via the control amplifier ST and the connection terminal 38.

In order to ensure that the time measuring units TBL and TIN discharge their capacitors 41 and 72 quickly, diodes 83 and 84 are connected across the resistors 42, 73 with such a polarity that they block the direction of the charging current, but the discharging currents of the forward the respective capacitors.

Tests with the system according to the invention have shown that it can be set with the following periods

Tel

Tre

Tsk Tin

about 0.5 seconds
about 0 to 20 seconds
about 8 seconds and
about 2 seconds

55

as well as a favorably selected value of the input sensitivity of the pulse amplifier 57 is possible, to separate a stack of 2 to 8 mm thick panels and a stack of 8 to 40 mm thick panels, without losing the top plate of the stack during the last separation.

Claims (12)

Patent claims: 1.Circuit arrangement for electromagnets for lifting and conveying plates made of magnetizable material, in particular iron plates, the current for the winding of the magnet or magnets being briefly interrupted in order to detach the upper plate from other plates adhering under it, then being switched on permanently, to hold the upper plate when conveying to its destination, and is switched off again at this in order to release the plate, characterized in that during the release of the plate caused by the short-term power interruption, a result of the remanence of the plate and the lifting magnet in the magnet winding induced voltage pulse is fed to an electronic control unit (11) which, after a short period of time (Tre) set in advance, switches on the current for the magnet winding again in order to hold the upper plate permanently. 2. Circuit arrangement according to claim 1, characterized in that the control unit (11) switches on the current for the magnet winding again after a predetermined time (Tin) , after which a voltage pulse induced in the winding is generated again by the remanence and is fed to the control unit , which interrupts the current again after the set short period of time (Tre) , and this process is automatically repeated a number of times set in advance. 3. Circuit arrangement according to claim 1 or 2, characterized in that the magnet winding via the electronic control unit (11) to a trigger circuit (10) for a controlled rectifier unit (2, 3, 4 and 5, 6, 7) is connected. 4. Circuit arrangement according to claim 3, characterized in that across the input terminals (12, 13) of the lifting magnet or magnets, a diode (16) is installed which is connected in series with the primary winding (15) of a transformer (14) Secondary winding (53) outer terminals (54ö, 55a) are connected to input terminals (54b, 55b) of the control unit (11). 5. Circuit arrangement according to claim 3 or 4, characterized in that the control unit (11) contains a controllable timing unit (TH) provided with an electronic output relay (24), the input of which is connected to a yoke via a flip-flop unit (23) of the magnet (1) provided for sensing contact is connected (18 b) and thus mechanically controlled, that the contact (18 b) is closed, when the yoke rests on the surface of a plate stack, wherein the output relay (24) of the time measuring unit (TH) so is connected to the flip-flop unit (23) that this is reset after a certain period of time (Th,) in which the yoke moves upwards. 6. Circuit arrangement according to claim 3 to 5, characterized in that the relay (24) of the first time measuring unit (777) is still connected to a second flip-flop unit (27), on whose Output an amplifier (28) with a contactor (29) is connected, the switch-off contacts (32) are connected in series with the power supply for the hoist motor. 7. Circuit arrangement according to claim 3 to 6, characterized in that the other output of the second flip-flop unit (27) is connected to one input of a control amplifier (ST) , the output terminal (38) of which is connected to the trigger circuit (10) and that this flip 109 540/25 Flop unit (27) blocks a control voltage supplied from said relay to said input of the control amplifier (ST) via its connection to the electronic relay (24) in the first time measuring circuit (TH) after the period (Th). 8. Circuit arrangement according to claim 3 to 7, characterized in that one input of the second flip-flop unit (27) is also connected to a controllable second time measuring unit (TSK) provided with an electronic output relay (33), the output relay ( 33) is connected to this flip-flop unit (27) in such a way that it is reset after a certain period of time (Tsκ) to switch off the control amplifier (28) and its relay (29). 9. Circuit arrangement according to claims 3 to 8, characterized in that the one output of the second flip-flop unit (27) via a first AND unit (44) also with a third controllable timing unit provided with an electronic output relay (40) (TBL) is connected, the output relay (40) via a line (48) is connected to a third flip-flop unit (43) that this is reset and a second line (50) opens a second and he unit (52) prepared for a voltage pulse (17) that arises across the input terminals (54 b, 55 b) when the controlled rectifier (2, 3, 4 and 5, 6, 7) is switched off. 10. Circuit arrangement according to claim 9, there- characterized in that the input terminals ( 54b, 55b) of the control unit (11) are connected to an input (59) of the second AND unit (52) via a pulse amplifier (57) and an electronic relay (58). 11. Circuit arrangement according to claim 10, characterized in that the output (63) of the second AND unit (52) through a fourth flip-flip unit (64) with an electronic output relay (68) provided fourth controllable timing unit [TRE ) and that the output relay (68) is connected to the control amplifier (ST ) via a line (74) and a third AND unit (62) so that the output terminals (38) of the amplifier after a certain period of time (Tre) a trigger voltage for the controlled rectifier (2, 3, 4 and 5, 6, 7) is supplied. 12. Circuit arrangement according to claim 11, characterized in that the output (63) of the second AND unit (52) through a fifth flip-flop unit (65) is also provided with a fifth controllable timing unit (71) provided with an electronic output relay (71) TIN) and that the output relay (71) via a line (82) partly to the second input of the second flip-flop unit (27) for resetting the fifth time measuring unit (Tjy) after a certain period (Tix), partly the third flip-flop unit (43) for the third time measuring unit (TBL) is connected. 1 sheet of drawings