ELECTRONIC AUTOMATIC CONTROL MACHINE FOR “ADRES-1” RELEASE DEVICES

V. G. TEREKHIN, M. A. ZHITKOV, L. S. UDUT, A. I. SAPOZHNIKOV,
A. I. ZAITSEV

(Recommended by the scientific seminar of the Electromechanical Faculty).

One of the main problems in the automation of continuous-transport mechanisms is the creation of devices for the automatic sorting of transported piece goods. Continuous-transport mechanisms include longitudinal conveyors of great length—100 m to 400 m—used in the timber industry at timber-transshipment bases for the purposes of transporting and sorting round timber and sawn materials.

A longitudinal conveyor—a log haul at a sorting section—is equipped with log release devices and pockets (accumulators), into which logs of a definite assortment, length, and diameter are discharged. Sorting is carried out according to indices marked on the end of a log, by push-button activation of the release devices directly at the pockets.

A disadvantage of such servicing is that it requires a large number of workers, entails considerable scattering of the log ends in a stack, and limits the conveyor speed. Therefore, automation of sorting makes it possible to reduce the operating personnel to a minimum, improve sorting quality, and increase the productivity of sorting lines while fully observing the technology for distributing timber among the accumulators.

However, in developing systems for automatic control of the release devices, a number of difficulties arise, caused by:

1) the absence of any regularity in the arrangement of logs on the conveyor;
2) the presence of conveyor elongation depending on the degree of loading;
3) random failure of a log to be released.

At present, a number of research and design organizations in the country are carrying out experimental work on the development and creation of such devices based on electromechanical and contactless elements.

It may be considered that the devices developed by the design organizations “VSNIPILesdrev,” Krasnoyarsk; “SevNIIP,” Arkhangelsk; “Promenergoavtomatika,” Sverdlovsk; “KNIILP,” Kirov, Moscow, Leningrad, and other organizations have not been fully developed to

industrial application and mass production because of a number of shortcomings inherent in one device or another, namely:

1) the use of contact elements;
2) the complexity of adjustment and unreliability in operation;
3) failure in the event of accidental non-discharge of a log and insufficient accuracy in issuing the command for discharge.

The mass-produced “order drum” device of VKFTsNII-Lesosplav, Kazan, did not find wide application, since it uses the principle of mechanical tracking and is implemented with contact elements.

Therefore, the most promising direction is the creation of devices based on contactless elements.

In this direction, the staff of the Department of EPP of TPI carried out work on the development, modeling, and testing under production conditions at the Tomsk LPDK of experimental models of automatic control devices for discharge mechanisms. Two variants were investigated:

1. A variant with a separate register for each storage bay.
2. A variant of a code system with a four-bit parallel code.

The code-system variant is difficult to adjust, requires careful selection of ferrite-transistor elements according to the duration of the output pulse, and is difficult to operate; moreover, the failure of one of the circuit elements disrupts the operability of the system as a whole.

Therefore, factory manufacture of a pilot-industrial model of the “Adres-1” electronic automatic control machine for discharge mechanisms was carried out according to the variant with separate registers for each storage bay.

Block Diagram of the “Adres-1” Machine

In its operating principle, the machine is a discrete tracking system as a function of the displacement path, in which the address of a storage bay advances in the information carrier synchronously with the movement of the log on the conveyor.

Fig. 1.

The machine is designed to operate with bin sensors, which make it possible, with a large discreteness interval (step), to achieve high accuracy in issuing the command to dump a log.

The block diagram of the machine is shown in Fig. 1. The machine control panel, PU, is located at the beginning of the sorting section on the line of the synchronizing-pulse sensor, DSI. The operator visually determines the grade of the log and, in accordance with the sorting technology, assigns its address by actuating one of the control keys. In doing so, a write signal is sent to the memory element of the corresponding information carrier of the electronic unit, BE, serving the given bin. The addressing of the log is performed at any moment after the rear end of the preceding log has passed the DSI line.

At the moment when the rear end of the addressed log passes the DSI line, by means of a pulse from the DSI, previously shaped and amplified in the synchronization device, US, the address of the log is entered into the information carrier. Thus synchronization is ensured between the position of the log on the conveyor and its address in the information carrier.

Each electronic unit serves two bins according to the following scheme:

BE-1 serves bins 1 and 18,
BE-2—bins two and seventeen, and so on.

Unit BE-10 serves the farthest bin, 19, and emergency bin 20. The linear displacement of the conveyor, by means of the travel-pulse sensor, DIP, is converted into a two-phase sequence of pulses with a discreteness interval of 2 m. The DIP consists of two inductive sensors, the closing of whose magnetic systems occurs in accordance with the selected discreteness step, and is coupled to the shaft of the driven roller. Through two channels, the travel pulses, shifted by 1/2 of the discreteness interval, shaped and amplified in the US, are sent to each electronic unit, BE, to start the clock generators, which provide discrete movement of the address synchronously with the movement of the log on the conveyor.

The system is constructed in such a way that the address moves in the information carrier with a certain lead relative to the rear end of the log, but by no more than 2 m. As the address of the log moves, it passes through a definite number of elements of the information carrier, corresponding to the number of meters to the bin, and is stored in the memory element.

After the information has been stored, by a pulse from the bin sensor, DP, at the rear end of the log, the stored information is read out. The log-presence signal acts on a device that forms an output pulse of adjustable duration, necessary for switching on the dumper.

The bin sensor is an optical system; a photodiode FD-1 is used as the receiver.

At the last bin the operator does not perform addressing, since it is an emergency bin, and all unaddressed logs and logs that for some reason were not dumped at their storage location enter it. The control circuit of the emergency bin is constructed so that any log reaching this bin is dumped by a pulse from bin sensor DP-20.

The bin control panels, PUP, make it possible to control the operation of each stacking location and provide:

1. Indication on the control panel PU of the state of the stacking location, on command of the operating personnel, when the bin is full, during unloading from it, and in the event of a dumper malfunction.

1. Disconnecting the release device from the control system while retaining push-button control.
2. Starting and stopping the conveyor.

Functional Diagram of the Electronic Unit

The main device of the machine is the electronic unit, the functional diagram of which is given in Fig. 2.

The information carrier of the electronic unit is a two-cycle, nonreversible shift register implemented on standard

Fig. 2.

ferrite-transistor cells, FTYa. The register consists of 206 FTYa cells and is an electronic model of a breviotape. With the selected discretization step of 2 m, the two-cycle shift register makes it possible to model 206 meters of conveyor, and to output information at intervals of 1 m.

The register is divided into two equal parts, each of which, in turn, is broken down into groups containing 1, 2, 4, 8, 16, 32, and 40 cells. The input and output of each such group are brought out to connectors Sh2 and Sh3, which makes it possible to implement all the units according to the same circuit and, with the aid of plug-in jumpers, to assemble two registers of the required length. The advancement of information through the registers is carried out by clock generators BG, built according to the circuit of a blocked blocking oscillator on a P201A transistor. The BGs are started by advancement pulses from the control system through the corresponding amplifier modules MU.

Entry of the address into the register is performed automatically, by reading, with the MU module, the address recorded in one of the memory cells P, in response to the DSI signal.

At the end of the assembled register, the address is stored in the output memory cell P, is read by the MU module in response to the signal of the arrival sensor DP, and starts the actuating device MI. A relay operates, the contacts of which switch on the release device. The ABG module, consisting of two self-oscillating blocking generators, makes it possible to convert the signals arriving at the MU input into ferrite-

transistor cell. The schematic diagram of the amplifier module MU is shown in Fig. 3. The MU contains an amplifier (PP3 and PP2), assembled according to a composite-triode circuit, and one ferrite-transistor cell. The module has two inputs; the first is used when control pulses are applied from the US, the second from the DP, and one output—the emitter circuit of the FTYA transistor.

Fig. 3.

A control pulse of negative polarity arriving at either input starts the amplifier (PP3–PP2). By the current of the open transistor PP2, in whose collector circuit the recording winding of FTYA is connected, the core of the pulse transformer of the cell is remagnetized.

At the end of the input pulse, the FTYA core is practically instantaneously remagnetized to its initial state by a current pulse from the ABG self-oscillating blocking oscillator. Transistor PP1 opens, and the current pulse of the ferrite-transistor cell is taken from the output.

Fig. 4.

The schematic electrical diagram of the actuator module MI is shown in Fig. 4. The MI consists of two pulse-duration shapers of the capacitive electronic time-relay type, assembled according to an emitter-follower circuit on transistors PP1 and PP4, a relay element PP2 and PP3, and a power amplifier PP5, PP6, assembled according to a composite-triode circuit.

The duration of the output pulse is determined mainly by the stage on PP4 and is regulated by the resistance R9 of the R9 C2 circuit, connected into the emitter circuit of PP4.

In the initial state the transistors PP1, PP2, PP4, PP5, PP6 are off.

The MI is started through the matching transformer Tr1 by a pulse from the output ferrite-transistor memory cell. Preliminary widening and shaping of the input pulse in the stages PP1, PP2, PP3 ensures complete charging of the capacitance C2 to the power-supply voltage. The time for which relay R remains energized is determined by the discharge time of C2. The considered circuit of the electronic time relay makes it possible to obtain an adjustable time delay in the range from 0.5 sec. to 1.5 sec. with a starting-pulse duration of 3–5 μsec.

The developed “Adres-1” machine has the following technical data:

1. Number of release devices serviced, with a sorting-section length of 200 m — 20.
2. Range of diameters of logs subject to sorting — determined by the capabilities of the release device.
3. Length of logs — not less than 3 m.
4. Conveyor speed — any from the technological range.
5. Distance between the ends of logs on the conveyor — not less than 5 cm.
6. Time for which the release device remains energized — adjustable from 0.5 to 1.5 sec.
7. Power of the output contacts of the relay that switches on the release device — 220 V, 2 A.
8. Scatter of the ends of logs in the stack — not more than ±20 cm.
9. Power supply of the machine:
   voltage 220 V ±20;
   frequency 50 Hz ±5 Hz;
   power consumption — not more than 0.3 kVA;

Structurally, the machine is made in the form of a rack with compartments, in which 10 electronic units, a power-supply unit, and one reserve electronic unit are housed.

The parallel method of synchronizing the operation of the units prevents impairment of the operability of the machine as a whole when any one of the electronic units fails. All electronic units are interchangeable. Jumper straps are soldered at the site in accordance with the length of the section serviced by the given unit of release devices.

Conclusions

Experience from production tests of the experimental prototypes makes it possible to draw the following main conclusions:

1. The use of contactless devices made on ferrite-transistor cells and elements operating in a switching mode increases the reliability of the machine.

2. The use of the DIP sensor eliminates the influence of humidity, contamination, and large temperature differences on the operation of the synchronization device.

3. The necessity of installing an emergency release device at the end of the sorting section, to receive accidentally unreleased logs or tem-

temporary use of it as the working one in the event of a malfunction of some sorting bay.

The “Adres-1” machine can be used as part of a unified system for measuring, recording, and sorting timber on longitudinal log conveyors.

It should be noted that the principles and circuit implementation of the machine can be used in automating the sorting of piece products in other branches of industry. At present, a pilot-industrial model of the “Adres-1” machine has been manufactured, adjusted, and tested under laboratory conditions and, with the beginning of the 1965 navigation season, will be put forward for industrial testing.