DD228377A1 - METHOD AND DEVICE FOR REGULATING HUMIDITY AND PLASTICITY OF STRUCTURED CERAMIC MASSES - Google Patents

Abstract

The invention finds application in treatment and shaping processes in which it is necessary to control the moisture or plasticity of the raw material mixture to be processed. Preferred application is the preparation and shaping of heavy clay products such as bricks, stoneware and Draenrohre. The aim of the invention is to carry out automatic metering of water, steam or solids at a low technical outlay so that the moisture content is kept constant within narrow limits in order to reduce the energy requirement of the drying, to improve the quality of the intermediate and end product and to save or relieve the workforce. The stated object is achieved by using, as input variables for the control device, indirect measuring variables of the humidity or plasticity and of the mass throughput, such as the current consumption, the electrical mains voltage, the pressing pressure and a counting rate of the sound strand cutter. The input variables are linked in such a way that the electrical active power absorption is used as the main control variable for the addition of the media to be influenced and derived signals are used as setpoint correction variables, as auxiliary control variables or as interfering forces for the purpose of interference power supply for the strand moisture or plasticity. Possible areas of application can be seen everywhere where plastic substances are processed and shaped. Fig. 1

Description

-A-

Title of the invention,

Method and device for controlling the moisture and plasticity of extruded ceramic masses

Field of application of the invention

The invention relates to the further development of a method and a device for controlling the humidity, and plasticity of extruded ceramic masses with regard to the extraction, linking and use of signals and the arrangement of electronic components.

The invention finds application in Aüfbereitungs- and Forragebungsprozessen - in particular the coarse ceramics production «where it is necessary to ensure good processability of the masses and high quality of the final product (brick), physical parameters, such as the mass moisture and plasticity or stiffness to keep within narrow limits by the addition of influencing media (water, steam, solids)

The technological scope of the invention extends from the first box feeder to the sound cutter after the extrusion press. Further delimitations of the range can only be determined in a specific manner because of the variety of technological possibilities.

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- 2 Characteristic of known technical solutions

Conventional technical solutions for the metering of the influencing media are the hand setting or control in connection without or rait display devices for Stromaufnähme of processing machines and the extruder and the pressing pressure ira press head of the extruder. The manual dosing requires considerable experience and skill "if not of uniform quality of the starting material is ensured and / or ^one stream of material is subject to fluctuations. There are already methods and systems for the automatic control of the physical properties of ceramic masses ira general and the moisture and / or piasticity in particular and thus the addition or · dosage of water, steam and / or dry substances known. They have the following special features:

- In a production chain consisting of mixer and extruder, the plasticity is used as a controlled variable ira mixer in a control loop, through the manipulated variable of the metering device is actuated, characterized in that the plasticity is measured in the press head of the extruder or on the clay and serves as Führangsgröße a cascade control whose auxiliary control variable is the plasticity measured in the mixer (DE-AS 23 26 969). /

- In a preferably the mixing point (Zugabesteile the influencing medium) upstream region of the conveying path, the flow rate of the mass to be prepared is determined and supplied as a disturbance of the setting of the supply of the additional media or determining actuators controlled system (DE-OS 15 84323). The throughput will be

, determined on the basis of a weight determination and / or feed rate.

- For a material processing plant u. a, consisting of one. Mixer with electric drive motor, a supply of material and a water supply, a control loop is provided for controlling the water content of the treated material. The current absorbed by the mixer drive rotor is fed as actual value of the water content into the control device.

, characterized by »that provided by the supplied current Therraouraforraer is provided (DT-AS 21 24 697). Among other things, the increased starting current is rendered ineffective by the use of a time relay. Furthermore, conventional current transformers with a rated value of 1 A or 5 A are used.

The listed processes or installations have in common significant disadvantages:

- Indirect measured variables for the plasticity and / or the moisture content, except for the pressing pressure, are taken without exception for the machine drives. · These current impressions are affected by fluctuating mass throughputs, filling levels and mains voltage fluctuations.

- Either the mentioned fluctuations are not taken into account, or, in addition to the usual treatment equipment, special technological and technical equipment is necessary to detect them.

-The traditional methods and controller components do not offer the possibility to consider time-variant controlled system parameters,

Although possibilities for more direct moisture measurement - for example on a microwave or infrared basis - exist in principle, they are too costly, in particular for coarse ceramic production, and too inaccurate for technological reasons.

- 4 Object of the invention

The invention aims to provide a method and a device which make it possible to carry out automatic water, steam or solid-material dosing at low equipment outlay in such a way that the mass moisture or plasticity is kept (regulated) within narrow limits and so that the energy required for the subsequent drying process lowered, workers released or at least relieved and the Committee of the intermediate or final product (Rohlingstrocken-, Ziegelbrennbruch) are lowered ·. -

Explanation of the essence of the invention

The invention has for its object to provide the configuration of a method and an apparatus apparatus which compensate with existing electronic and conventional BMSR technical means, the existing fluctuations in the strand moisture and plasticity as far as possible, so that the mentioned under the aim of the invention technical and economic In particular, the usual operating fluctuations, such as fluctuations in the mass throughput or the degree of machine filling (s), the mains voltage and the water pressure are taken into account and thus essential deficiency of. eliminates known technical solutions, without additional technological (raaschinentechnischen) effort to drive or use consuming Moisture Moisture.

The method according to the invention is characterized in that indirect measured variables of the moisture or plasticity and the mass throughput in the form of the current consumption (s), the electrical mains voltage and, if necessary, the pressing pressure and a counting rate of the sound strand cutter are used as input variables Input variables are in this case carried out such that the electrical Wij.rk-

power consumption (s) as the main control variable (s) for adding the affecting media and derived signals characterizing mass throughput or plasticity; As a setpoint correction values, as auxiliary control variables or as disturbance variables for the purpose of feedforward control, the material moisture content or plasticity can be used appropriate clocking and storing to take into account «The clock frequencies are either fixed, manually adjustable or independently depending on the mass flow rate to make it changeable. The use of the derived signals for the mass throughput and the plasticity (moisture) as well as the consideration of the transit times serves both the improvement of the control quality and the control dynamics. By specifying and setting desired values for the electrical power, the throughput and the pressing pressure, the machine-related changes (replacement, wear) can be taken into account. The variables (signals) used in the regulation are obtained or used according to the invention as follows:

Leiatunqssiqnal

by multiplicatively combining the analog instantaneous values of current consumption and mains voltage with subsequent smoothing or filtering. The control loop requires a power signal as the main control variable.

Mass flow rate signal

either by counting the number of clipping operations on the clippers within a unit of time to be set in accordance with the format produced (blank weight)

- or by linking the power signals of the electric drive rotors of two sequentially arranged processing machines, wherein between two machines by a water metering a constant amount of water or one of the first power signal controlled Wasserraenge is added, ein.handeingestaltter value or _: the control signal, the added (pre-dosed) amount of water The linkage of the clocked power signals is realized after a weighting with one factor (gain) to be set via a subtraction and subsequent division by the control signal variable. The actual controlled system for the strand moisture or plasticity must be arranged downstream of the two processing machines mentioned, d , At the earliest, the power signal of a third machine drive can be used as the main control variable of the water metering control loop.

-or by linking an "upper" and a "lower mean power signal of an electric drive motor with impulsärtiger dosing, wherein the" lower "value of the period of water addition is assigned, with the control signal for the water metering analogous to the above variant · But this in contrast the mean value of "lower" and "upper" power signal and the control signal for water metering signals of the control system for strand moisture and plasticity control, ie power signals of upstream machines are not needed and subordinate machines serve except their other technological purposes only the equalization of moisture and plasticity ·

clock signal

All measuring signals are to be clocked according to the time (in relation to the corresponding water metering point) in such a way that the running time of the cycle time is adjusted. Either the

Cycle times of the clock manually set by hand or they are automatically adjusted after a default depending on the mass flow rate,

Stellsiqnäl

The control signal, which represents the output signal of the strand moisture and plasticity control device, arises via the timely combination of the above-mentioned input or intermediate signals, wherein the selection of the structure of the control device and determination of the signal use z. B / _a ig setpoint correction variable, reference variable, disturbance variable or auxiliary control variable must be coordinated with one another · If required, the input and / or intermediate signals can already be interconnected with supply versus setpoint values ·

The entire plant for strand moisture or plasticity control and thus for metering the influencing media represents a BMSR system whose essential part erfinduhgsgemäß a special electronic control device that allows to realize the above control method with its addition to the main controlled variable signals The multi-channel electronic control device, consisting of components known per se, such as transducers (filters, amplifiers, smoothing elements), comparators, A / D primers, clocks, memories, Zählirapulsgeber and returns), erfindungsgeraäß characterized by the fact that a main variable derived signal representing a measure of the active power consumption of an electric machine drive motor. Use is made and beyond further additional signals, which in turn may be both power signals and mass flow rate signal, Preßkopfdrucksignal and / or actuating signal can be used.

By forming the difference between the associated setpoint and actual values of the signals in input amplifiers, deviations are

formed by means of comparators, the effective direction of the generated control signal is positive or negative, ie. the throughput of the influencing medium must be increased or decreased proportionally. The sign signals are buffered in a sign memory and used to determine, after the formation and digitization, whether the digital value corresponding to the respective deviation signal amount is fed to the positive or negative counter of the Stellirapulsgebers · Both counters are started at the same time · The length of the Stellirapulses is from the expiration impulses (Nullurchgangsirapulsen) both counters limited »the direction of action of Stellirapülses derived from the first impulse * The individual control channels are characterized in that the (analog) deviations of the respective controlled variable weighted according to their influence strength (amplified) and after digitizing according to the respective controlled system running time, delay time, compensation · time can be clocked differently. The required clock signals are provided by a clock center, they are manually adjustable and / or programmable and / or influenced by a mass flow rate · About electronic feedback is a signal that is representative of the flow rate of the influencing medium (eg, as Ventilstellungfsrückraelduhg ), fed back to the inputs of the control channels, which makes it possible. to generate the control behavior (eg PID-like) desired for the individual channels. The control structure and partly the controller parameters are to be realized either by a pure hardware arrangement or by means of a microcomputer system comprising both hardware and software.

Ausführungsbeispie le

To further explain the invention, the following five exemplary embodiments serve with the corresponding drawings

Fig. 1 ··· Fig. 5

1 shows a strand moisture or plasticity control loop on a conditioning or shaping machine 1 with the associated electromotive drive 2, with a current transformer 3 in the electrical supply line and the Massestrora 4 (sound) and the flow of the influencing medium 5 (water, The power converter 8, the input of which is connected to two phases of the power supply and the current transformer 3, supplies the active power signal, which is used as the main control variable 9 · The main controlled variable 9, the mass terrestrial signal 10, the return or return signal 12 received from the remote encoder 11, the desired values 13 and ¹ associated with the listed signals, together with the desired values 14 represent the input variables for the multichannel controller 15 whose output is the actuating signal 16 for the Actuator 7 supplies ·

1 shows two processing machines 17 and 18 with the associated electromotive drives 19 and 20 and the power transducers 21 and 22 in the electrical supply lines. The two processing machines 17 and 18 are successively traversed by the mass flow 4, wherein between two machines a Vordosierstron the influencing medium 23 (water, steam) via the valve 24 the mass flow 4 (clay) is added Ira difference to Fig. I is the valve 24 with the motor actuator 25th not a control loop, but a timing chain consisting of the current transformer 21, the power converter 25, the adjustable amplifier 27 and other control components 28 · The active power signals 30, 31 obtained via the current transformers 21, 22, the power converters 26, 29 become a two-channel electronic evaluation unit 32 supplied · The two Kan Each consists of an adjustable amplifier 33 or 34 and

a delay and storage element 35 or 36 · The channel output signals are a Sumraationsglied 37 in order

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Difference formation supplied. The obtained difference size 38 is supplied as Divid.ent and the Erre from the positioner 40 tene Rückraeldesignal 41 of the control valve 24 to an adaptation by the Meßgrößenwandler 42 as divisor signal 43 to the divider member 39. The output signal of the divider 39 represents the mass terrestrial signal 10 used in FIG.

FIG. 3 shows another arrangement for forming the active power signals 30 and 31 which, together with the feedback signal 41 (12) in the electronic evaluation unit 32 according to FIG. 2, processes the mass flow signal 10 of the controlled system (1 - 8) according to FIG become. The signals and control circuit components 9 - 15 as shown in FIG. 1 also apply with the difference that in the supply of the influencing medium (water, steam) an additional solenoid valve 44 which clocked by an adjustable clock 45 via a relay with two changers 46 and fed via the power supply 47 is located. The active power signal 9, which continues to be supplied to the regulator 15 as the main control variable, is alternately switched via the second changeover switch of the relay 46 to the two transducers 48, 49, which primarily fulfill a smoothing function. The smoothed active power signals 30 and 31 and the return signal 41, which continues to serve as the feedback signal 12 for the controller 15, are processed in the electronic evaluation unit 32 according to FIG. 2 to the mass terrestrial signal 10.

FIG. 4 shows an arrangement for determining the mass flow rate 10 by counting the cutoff operations on the audio cutter. The wire tear detector 50 which is connected to a voltage supply 51 supplies the toe signal 52 which is matched in the level converter and signal filter 53 to the input of the counter 54 , The adjustable clock 55 determines the count duration and provides both the reset signal 56 for the counter 54 and the upper limit signal 57 for the counter 58, which after a buffering in the memory 59 in the D / A converter 60 in · '.

  - 11 -

the quasi-analog mass current signal 10 is converted.

5 represents the overview circuit diagram for the multichannel electronic strand moisture or plasticity regulator 15. The regulator consists of two or more control channels 61 and the pulse generator unit 62. The input signals of each control channel are the respective controlled variable 63, the associated desired value 64 and possibly the Rückraeldesignal 65, the latter size or signals corresponding to the signals 9, 10, 12, ... 14 of FIG. 1. The RücknieIdesignal 65 passes through the electronic feedback 66 together with the Sollwerf 64 on the input amplifier 67, whose output along with the controlled variable 63 are connected to the inputs of the amplifier 68 and the sign trigger 69. The amplifier 68, an A / D converter and a code converter 71 are connected downstream · The output assignments of the code converter 71 and the sign trigger are taken from the memory register 72 with the measuring clock 73. The further transfer to the storage register 74 is made with the clock 75, which takes into account the respective control cycle runtime, transition time · The subsequent gate 76 switches according to the sign, the channel output to the minus and plus bus line (buses for all channels) 77, the Irapulsgeber 62 leads ·

The input of the Irapulsgebereinheit 62 consists of a Doppelraultiplexer 78, the bus line 77 in accordance with the sign and channel by channel with the following double counter

79 connects and the with the help of the counter control

80. Each of the counters of the double counter 79 are counted backwards to the counting clock 82. All the required clocks. Both the counting clock 82 and the basic clock 83 for the counter control 80 and the channel clocks 84 (Figs. 73 and 75) are output from the Clock center 85 provided. Depending on the Zählullulldurchgangsimpulsen 86 and the basic clock 83 from the counter control 80 in addition to the already mentioned load signals 81 and the switching signals 87 for

the dual-track multiplexer 78 is provided. The evaluation of the counter zero-crossing impulses of all channels 61 ira

Character and pulse length encoder 88 provides the pulse length-modulated actuating signal 89, in which the pulse length corresponds to the propagation time difference of both counters of the double counter on a single scan of all channels 61, and the direction signal (open-close signal) 90, the first expired counter with a single scan of all channels 61 is determined

Claims (7)

, , - 13 claims to invention 1. A method for the automatic control of the moisture and plasticity of extruded ceramic masses by the addition of influencing media, such as water, steam or solids, via one or more dosing device (s) of a production chain in the treatment / forrage between (first) (box) ) Feeder and Tonabschneider after the extruder, as the controller input variables indirect measures of moisture and plasticity are used and the controller output variable (s), the manipulated variable (s) (16) for one or more metering devices is (are), characterized in that as the main controlled variable the derived from Stromaufnähme and mains electrical Wirkwirkaufaufme (9) of a machine drive (2) and also another from indirect measured variables derived regulator input signal (10), which characterizes the mass flow rate (4) of the ceramic mass (Tön). Is used, further additional input signals (12 ... 14) can be used and the processing of the input signals (9, 10, 12, ,, 14) thereby raehrkanalig done and this further clocked according to the respective control cycle runtime, delay time and compensation time, cached or otherwise delayed and only then linked to one or more actuating signal (s) {16). 2. The method according to item 1, characterized in that the mass throughput or machine filling degree by counting the cutting operations on the Tonabschneider within a unit time, which is set in accordance with the 'manufactured product (format) or average blank weight, is determined. 3. The method according to item 1, characterized in that the mass throughput or machine filling degree by the Ver Linking of the active power signals _# (30, 31) of two electric drive motors (19, 20) successively arranged processing machines (17, 18) between which a predosing of the influencing medium is made is obtained, the two machines the actual strand moisture and plasticity control technologically seen upstream and the predosed amount of the influencing medium is set constant or by the active power signal (30) of the first of the two processing machines (17) is controlled and the addition of the influencing medium is blocked when the Massestrora the sound (4) interrupted is. 4. The method according to item 1, characterized in that 'the mass flow rate or machine filling degree determined by the combination of an' upper ** and a 'lower' average active power signal (30, 31) only one electric drive motor (Z) of a processing machine (1) is, with an irapufeartige dosage of the influencing medium takes place and the "upper" value to the state without and the "lower" value is assigned to the state with water addition and said active power signals either the strand moisture and -plaatizitätsregelkreis associated or upstream of this 5. The method according to item l, characterized in that the combination of the active power signals (30, 31) for mass strand signal (.10) after weighting (gain) on the formation of a / * difference is made, which in turn related to the metered amount of the influencing medium or divided by them. 6. Multi-channel control device for carrying out the method according to item 1 - 5, consisting of known per se electronic components, such as transducers
(Filters, amplifiers, smoothing elements) comparators, A / D converters, clocks, memories, counters and feedback (s), characterized in that the channels (61) are similar in construction in terms of smoothing, filtering, amplification, timing and feedback and separate adjustable and · variably equipable · 7. means for determining the Massestrorasignales (10) according to item 1 - 5, characterized in that two active power channels, each successively from
an adjustable evaluation amplifier (33, 34) and a Ver, delay and storage member (35, 36) consist, via a subsequent common summation element for subtraction of the evaluated benefits
are connected to each other and in turn a divisional member (39) is arranged, wherein the weighted power difference size (38) as a divide and the additional external flow rate for the influencing medium (eg feedback signal of a control valve) are connected as a divisor (43) and at the output the quotient as a signal for the MaS'sestrora, resp.