EP3103354B1 - Method, applicator and machine for producing a filter rod in the tobacco processing industry - Google Patents

Description

The invention relates to a method for producing a filter strand of the tobacco processing industry in which a strip of filter material spread the tobacco industry, sprayed in the expanded state with a liquid additive through at least one application nozzle and then formed into a filter strand, said additive from an additive reservoir in an inlet to the at least one application nozzle is pumped and sprayed additive, which is not absorbed by the strip of filter material, is returned by a return to the additive reservoir, and a corresponding applicator and a machine of the tobacco processing industry.
In the production of filter strands for the tobacco processing industry, a strip of filter material, usually a filter tow, which is usually made of cellulose acetate, withdrawn as a quasi-endless strip from a supply and treated. The filter tow consists of a fabric of loosely adhering threads that form a wide and flat web pulled apart. This propagation takes place by means of a spreader nozzle. After stretching and spreading, the web is fed an additive which is mostly liquid and consists, for example, of a plasticizer, such as triacetin, in finely divided form. The softener droplets dissolve the filaments so that when they are combined into a round filter strand and wrapped with a filter paper strip, they permanently adhere to one another in a filter rod machine.

In the application of additive to the strip of filter material, the uniformity of the order is of great importance, since the amount of applied additive affects the filtration properties of the filters thus produced. Therefore, it must be ensured that the amount of plasticizer or additive contained in each filter remains constant over the time of production or within predetermined tolerances.

Out DE 199 59 034 A1 It is known to spray filter tow with a transverse to the direction of movement of the filter tow row of nozzles with an additive or a plasticizer. Here, the individual nozzles are controlled by upstream, the density of the filter tow in the sections concerned sensors.

When using application nozzles, a constant pressure in the supply line to the application nozzle is alternatively used, so that the desired fine distribution of the droplets of the additive remains ensured. In order to be able to control the amount of additive introduced into the strip of filter material, is in DE 10 2005 015 877 A1 For example, discloses a device in which by a constant delivery pressure of the additive or plasticizer by means of spray nozzles uniform application of the plasticizer is achieved on the applied filter tow. Plasticizer not absorbed by the filter tow is collected in a catch basin or drip pan. It is also disclosed a cover plate, by means of which the application surface by moving the cover plate can be increased or decreased. In order to check that the amount of additive in the individual filters remains constant over the production time, individual filters are usually taken randomly and weighed, whereby several hours can pass between the samples. In EP 1 935 261 B1 a closer control is proposed by filling a calibrated container with a well-defined quantity of additive, removing it from the additive and applying it to filter material strips by means of a rotating brush which receives additive and sprays finely divided by rapid rotation. Unaccumulated additive is returned to the container. Electronic sensors give signals when the level falls below an upper level and falls below a lower level. After falling below the upper level level, a count of the produced filter is started and stopped after falling below the lower level level, so that it is known exactly how many filters the known volume of additive has been used. From this, the average amount of additive per filter produced is determined for this measurement. After falling below the lower filling level, the volume is replenished and another measurement is started, so that there is a cyclical monitoring of the amount of additive in the filters produced.

Another relevant procedure is in GB 2 066 707 A described.

In contrast, the present invention has the object to further improve the monitoring of the entry of additive in the filter material strip.

This object is achieved according to claim 1 by a method for producing a filter strand of the tobacco processing industry in which a strip of filter material spread the tobacco processing industry in the spread state with a liquid additive sprayed through at least one application nozzle and then formed into a filter strand, wherein additive from an additive reservoir through a Feed to the at least one applicator nozzle is pumped and sprayed additive, which is not absorbed by the filter material strip, is returned by a return to the additive reservoir, solved, which is further developed in that an inlet volume flow v̇ _{inlet of} the additive in the inlet and a return flow v̇ _{Return of} the _admixture in the return can be determined and a differential volume flow v̇ _{diff of} the additive is determined as the difference between inflow volume flow v̇ _inlet and return flow rate v̇ _{R ü cklauf} , which is used as a controlled variable of a volume flow control of admixture and a predetermined or predeterminable desired volume flow v̇ _target is regulated out.

The invention is based on the recognition that the transition from the introduced amount of additive, for example plasticizer, in particular triacetin, to a volume flow of the introduced additive allows a qualitative leap from a cyclic monitoring to a continuous monitoring. To capture the amount of additive introduced had always been integrated over a certain amount of additives, so that only an average entry per filter over a certain measurement period was detected. On the other hand, the volume flow is detected instantaneously or continuously, so that an individual measurement result can be assigned to each individual filtered filter rod. As in the prior art, the additive is used in a cycle by being conveyed from the additive reservoir through the inlet to the applicator nozzle, and additives that have not been taken up by the filter material strip are collected and returned by a return to the additive reservoir. The additive taken up and removed by the filter material strip forms a volumetric flow which, in the case of equilibrium, represents the difference between the inlet volumetric flow and the return volumetric flow.

For volumetric flow control, a setpoint volumetric flow is used as the setpoint for the controlled variable, namely the differential volumetric flow. Absolute values of the filling level in the collecting container or in the additive reservoir or intermediately stored containers are of no importance in the first place.

An advantageous further development provides that in addition a level control in a arranged before or in return level container with the control target of a vanishing time derivative ḣ _Soll = 0 of the time course of a level in the level tank takes place, with a control of the inlet volume flow v̇ _inlet and / or the return-flow rate V _{R e cklauf} done. For this second regulation, it is also not on the absolute value of the level in the level tank on, but only on the change in level height with time, which should disappear. So it depends on the constancy of the filling level, not on the actual value of the filling level. Characterized in that the level in the level tank is constant, it is ensured that the differential volume flow, which is the control variable of the volume flow control, exactly corresponds to the volume flow of the removed with the filter material strip additive.

Even in the case that the filling level changes, can be determined from the change in the level height, so the first time derivative of the level height , a correction for the controlled variable differential flow v̇ _{diff of} the flow control and thus adjust the scheme to it.

To control the return flow rate v̇ _{R ü cklauf} preferably a proportional valve in the return or a pump speed of a return pump in the return is adjusted. This has the advantage that the inlet can be operated at a constant pumping speed or at a constant pumping pressure in order to ensure the most uniform atomization or atomization of the additive in the at least one application nozzle. Therefore, the control of the volume flow in the return is more suitable for the filling level height control than that in the inflow. In other cases, where a good atomization is ensured even with different inlet flow rates, and the inlet flow rate can be controlled for this purpose. This is usually the case within certain tolerance ranges.

In an advantageous development, a control of a quantity of additive introduced into the strip of filter material takes place by means of a sheet, which is at least partially insertable into a spray cone produced by the at least one application nozzle. With a reduction of the application surface by inserting the sheet into the spray cone of the at least one application nozzle, the amount of additive, which is not absorbed and thus must be recycled, increased. The return flow increases accordingly, or the level in the level tank increases. When pulling out the sheet, it is the other way around. Accordingly, the control of the return flow rate through the level height control, possibly also the control of the inlet flow rate, to adapt to reach the control target of the constant level height.

In two advantageous alternatives, which can also be used alternately, depending on the machine operation, it is provided that the volume flow control is operated time-discretely, at least in periods of dynamic machine behavior, continuously and / or at least in time intervals of constant machine behavior. Dynamic machine behavior means, for example, starting and stopping the machine. In these time periods, the engine speed changes very much, as does the engine temperature. Therefore, the order conditions for the additive change quite quickly, so that a continuous control of the flow rate is advantageous. Especially in these times of dynamic machine behavior, the regulation according to the invention via volume flows is clearly superior to the regulation of volumes because of their speed. In temporal sections of constant machine behavior, ie approximately constant machine speed and other conditions, the control effort can be reduced by the volume flow control is operated time discretely.
Advantageously, an amount of additive per filter or each filter length, or unit length is calculated in the filter rod from an engine speed and the differential volume flow V _diff, and optionally a predetermined filter rod length. The unit of length is, for example, cm of the filter strand.
Further preferably, insufficiently sprayed filters are discharged, which were sprayed at a time at which the difference volume flow v̇ _diff deviated beyond the predetermined volume flow v̇ _target beyond a predetermined or predeterminable tolerance value or the calculated amount of additive per filter or per Filter length or unit of length in the filter train over a predetermined or predeterminable tolerance value deviates from a desired amount.
The volume flow control is advantageously adapted so that the desired volume flow of the additive is proportional to the machine speed. This ensures that the amount of added in the filter material strip additive is independent of the machine speed.

The object of the invention is based on claim 8 also by an applicator for applying a liquid additive to a spreading filter material strips of the tobacco industry, comprising at least one application nozzle, a Zusatzmittelvorratsbehälter, an inlet and an inlet pump, by means of the additive from the additive reservoir through the inlet to the at least one applicator nozzle is pumped or pumped, and a return, by means of which not included in the filter material strip additive is traceable into the additive reservoir, solved, which is further developed by an inlet measuring device for measuring an inlet volume flow v̇ _{inlet of} the additive in Inlet and a return measuring device for measuring a return flow volume v̇ _{R ü cklauf} the additive are included in the return and a flow control device, which is designed a difference volume flow v̇ _{diff of} the additive as a difference between inlet volume flow v̇ _inlet and return flow v̇ _{R ü cklauf} to be determined and used as a control variable for a volume flow control of Zusatzmittelsauftrag and to regulate a predetermined or predeterminable desired flow rate v̇ _target out.

By means of the applicator according to the invention, the features, advantages and properties of the method according to the invention described above are realized in the same way. The volumetric flow control device is preferably a controller with continuous behavior, for example a P, PI, PD or PID controller. The controller can be analog or digital.

In addition, a fill level container arranged in front of or in the return line, which is designed in particular as a collecting trough, and a filling height control device , which is designed to control the inlet volume flow v̇ _inlet and / or the return volume flow v̇ _{R ü cklauf} with a control target of a vanishing temporal Derivative ( ḣ _nominal = 0) to control a time course of a level height in the level tank . The filling height control device is a corresponding preferably continuous and linear regulator.

In an advantageous development, a controllable proportional valve and / or a controllable return pump is or are arranged in the return.

Also advantageously, a sheet is included, which is at least partially inserted into a spray cone generated by the at least one application nozzle to control an amount of registered in the filter material strip additive.

Fig. 1

eine schematische Darstellung einer erfindungsgemäßen Auftrageinrichtung,

Fig. 2

ein weiteres Ausführungsbeispiel einer erfindungsgemäßen Auftrageinrichtung und

Fig. 3

ein weiteres Beispiel einer erfindungsgemäßen Auftrageinrichtung in schematischer Darstellung.

The inlet measuring device and / or the return measuring device is or are advantageously designed as a volume flow measuring device or as a speed measuring device for a pump.
The applicator is preferably designed and configured to carry out a method according to the invention described above.
The object underlying the invention is finally achieved by a machine of the tobacco-processing industry with a previously described applicator according to the invention.
The machine also has the same features, advantages and properties due to the applicator according to the invention contained therein, as the subject invention described above.
Preferably, a discharge device is provided for discharging filter rods cut to length from the filter rod, by means of which filter rods can be removed which are insufficiently sprayed.
Further features of the invention will become apparent from the description of embodiments according to the invention together with the claims and the accompanying drawings. The invention will be described below without limiting the general inventive idea by means of embodiments with reference to the drawings, reference being expressly made to the drawings with respect to all in the text unspecified details of the invention. Show it:

Fig. 1

a schematic representation of an applicator according to the invention,

Fig. 2

a further embodiment of an applicator according to the invention and

Fig. 3

a further example of an applicator according to the invention in a schematic representation.

In the drawings, the same or similar elements and / or parts are provided with the same reference numerals, so that apart from a new idea each.

Fig. 1 shows an inventive applicator 10 in a schematic representation, wherein the control devices are omitted for reasons of clarity. It is a section of a machine of the tobacco-processing industry, not shown, in which an already spread filter material strip 12 is conveyed by means of two pairs of rollers 16, 18 in a conveying direction 14. Between the pairs of rollers 16 and 18 of the filter material strip 12, for example, a cellulose acetate tow, passed over a applicator 22, which may also be a series of juxtaposed applicator 22, the spray cone 21 from a formed into a spray liquid additive 20 in the direction on the filter material strip 12, ie upwards, gives off. The additive may, for example, be a plasticizer, for example triacetin. By the reference numeral 24, a volume flow of the additive 20 is designated, which is removed with the filter material strip 12 from the applicator 10. This removed additive volume flow 24 is ideally dimensioned such that per unit length of the filter material strip 12 the same amount of additive 20 is present.

The application nozzle 22 is arranged in an upwardly substantially closed container with a collecting trough 26, is caught in the additive 20, which is not absorbed by the filter material strip 12. This results in a level 28 in the tub 26th

At the bottom of the Fig. 1 a Zusatzmittelvorratsbehälter 38 is shown, which has a supply of additives 20 and with two lines, namely an inlet 30 and a return line 34 is connected, which are immersed in the form of dip tubes in the additive 20 in the additive reservoir 38.

The inlet 30 is provided with an inlet measuring device 32 and a means, not shown, for pumping additive 20 from the additive reservoir 38 to the application nozzle 22. The return 34 is provided with a return measuring device 36. The inlet measuring device 32 may also be a measuring device which, for example, determines the rotational speed of the pump (not shown). In this way, the inflow volume flow of additives 20 can also be determined.

In the Fig. 1 shown applicator 10 thus already provides all the information that is necessary for a flow control according to the invention.

Concrete embodiments of the scheme are in the FIGS. 2 and 3 shown schematically in more detail.

Fig. 2 shows an applicator 100 according to the invention, which in many details similar to the applicator 10 from Fig. 1 is constructed. In addition, the applicator 100 comprises Fig. 2 nor a displaceable plate 60, with which the application surface can be reduced in that the sheet 60 is pushed into the spray cone 21 and thus covers part of the spray before this part of the additive 20 can reach the filter tow or the filter material strip 12.

At the bottom of the Fig. 2 a volumetric flow control 50 is shown, which comprises a volumetric flow control device 52, which receives in its input a prepared input signal. This will be as follows generated. The inlet measuring device 32 and the return measuring device 36 each give a signal which corresponds to a measured inlet volume flow v̇ _inlet or a return flow volume v̇ _{R ü cklauf} . These signals are fed via data lines 51, 53, which may also be signal lines, to a differential image 54, which forms a differential volume flow v̇ _Diff from the two volume flows . This difference signal is supplied via a further data line 55 to a further difference images 56, which subtracts this difference signal V _diff by a flow command signal V _target. The result of the control is forwarded via a control line 58 to a control device, not shown, for the displaceable sheet 60, which is displaced accordingly, so that the application surface of the additive 20 on the filter material strip 12 increases or decreases.

A second control loop is in the form of a filling height control 70 in the right part of Fig. 2 shown. A signal on the level 28 in the drip tray 26, which acts in this case as a level tank 71, is differentiated in time and passed via a data line 78 to a difference image 74, this time-derived signal from a signal with respect to the target level height change ḣ _Soll , which is set to 0 subtracts. A filling height control device 72 of the filling height control 70 uses this signal to open or narrow a proportional valve 80 in the return 34 via a control line 76 when the level 28 is not constant. Alternatively, the signal for the level 28 can also be compared in the difference image 74 with a time-delayed signal in order to generate in this way the time derivative of the level.

Fig. 3 shows a further embodiment of an applicator 102 according to the invention, which differs from the applicator 100 in several points. Thus, in this embodiment, both in the flow 30 and in the return 34 in each case instead of volumetric flow measuring devices pumps, namely a feed pump 33 and a return pump 37 are provided, the pumping speed respectively as a measure of the volume flow of the additive 20 in the inlet 30 and in Return 34 is used. In the return 34 also an independent level tank 71 is disposed below the collecting beam 26, which allows a very accurate determination of level heights and level height changes due to a constriction. Also unlike Fig. 2 is in Fig. 3 for level control by means of the level control device 72 directly the pump speed of the return pump 37 is controlled. The remaining details of the applicator 102 correspond to those of the applicator 100 described above Fig. 2

LIST OF REFERENCE NUMBERS

10

applicator

12

Filter material strips

14

conveying direction

16, 18

roller pair

20

liquid additive

21

spray cones

22

application nozzle

24

removed additive volume flow

26

drip tray

28

level

30

Intake

32

Feed-measuring device

33

feed pump

34

returns

36

Return-measuring device

37

Return pump

38

Additive reservoir

50

Volume Flow Control

52

Flow control device

51, 53

data line

54, 56

difference images

58

control line

60

sliding sheet metal

70

Filling height control

71

level container

72

Füllhöhenregelvorrichtung

74

difference images

76

control line

78

data line

80

proportional valve

100

applicator

102

applicator

v̇ _inlet

Intake volume flow

V _{R overtime}

Return flow

v̇ _Diff

Differential volume flow (V _supply - V _{R ü cklauf)}

v̇ _Soll

Set volume flow

ḣ _should

Target level altitude change

Claims (15)

1. A method for producing a filter strand of the tobacco processing industry, in which a filter material strip (12) of the tobacco processing industry is spread out, sprayed with a liquid additive (20) by at least one applicator nozzle (22) while in the spread-out state and then formed into a filter strand, wherein additives (20) are pumped from an additive reservoir (38) via a supply line (30) to the at least one applicator nozzle (22) and sprayed additive (20) that is not absorbed by the filter material strip (12) is fed via a return line (34) back to the additive reservoir (38), characterized in that a supply volume flow (v̇_supply ) of the additive (20) in the supply line (30) and a return volume flow (v̇_return ) of the additive (20) in the return line (34) are measured, and a differential volume flow (v̇_Diff ) of the additive (20) is determined as the difference between the supply volume flow (v̇_supply ) and the return volume flow (v̇_return ), which is used as a control variable of a volume flow control (50) of the additive application and which is regulated to a predetermined or predeterminable target volume flOW (v̇_target ).
2. The method according to Claim 1, characterized in that in addition, in a level-controlled tank (71) located before or in the return line (34), a fill level control (70) is performed with the control target of a vanishing time derivative (ḣ_target = 0) of the temporal progression of a fill level in the level-controlled tank (71), wherein a controlling of the supply volume flow (v̇_supply ) and/or of the return volume flow (v̇_return ) occurs.
3. The method according to Claim 2, characterized in that a proportional valve (80) in the return line (34) or a pump speed of a return pump (37) in the return line (34) is adjusted for controlling the return volume flow (v̇_return ).
4. The method according to one of Claims 1 to 3, characterized in that a quantity of additive (20) incorporated in the filter material strip (12) is controlled by means of a plate (60), which can be at least partially inserted in a spray cone (21) generated by the at least one applicator nozzle (22).
5. The method according to one of Claims 1 to 4, characterized in that the volume flow control (50) is operated in continuous fashion, at least in time periods of dynamic machine behaviour, and/or in time-discrete fashion, at least in time periods of constant machine behaviour.
6. The method according to one of Claims 1 to 5, characterized in that a quantity of additive (20) per filter or per filter length or length unit in the filter strand is calculated from a machine speed and from the differential volume flow (v̇_Diff ), and optionally from a predetermined filter rod length.
7. The method according to one of Claims 1 to 6, characterized in that insufficiently sprayed filters, which had been sprayed at a point in time at which the differential volume flow (v̇_Diff ) deviated from the target volume flow ( v̇_target ) beyond a predetermined or predeterminedable tolerance value or the calculated quantity of additive (20) per filter or per filter length or length unit in the filter strand deviates from a target quantity beyond a predetermined or predeterminable tolerance value, are removed.
8. An applicator (10, 100, 102) for applying a liquid additive (20) on a spread-out filter material strip (12) of the tobacco processing industry, comprising at least one applicator nozzle (22), an additive reservoir (38), a supply line (30) and a supply pump (33), by means of which additive (20) can be pumped or is pumped from the additive reservoir (38) via the supply line (30) to the at least one applicator nozzle (22), as well as a return line (34), by means of which additive (20) not absorbed in the filter material strip (12) can be fed back into the additive reservoir (38), characterized in that a supply meter (32) for measuring a supply volume flow (v̇_supply ) of the additive (20) in the supply line (30) and a return meter (36) for measuring a return volume flow (v̇_return ) of the additive (20) in the return line (34) are included as well as a volume flow regulator (52), which is configured to determine a differential volume flow (v̇ _Diff ) of the additive (20) as a difference between the supply volume flow (v̇ _supply ) and the return volume flow (v̇_return ) and use it as a control parameter for a volume flow control (50) of the additive application and to regulate it to a predetermined or predeterminable target volume flow (v̇_target ).
9. The applicator (10, 100, 102) according to claim 8, characterized in that it also includes a level-controlled tank (71) located before or in the return line (34), which is in particular configured as a catch pan (26), as well as a fill level regulator (72), which is configured to control the supply volume flow (v̇_supply ) and/or the return volume flow (v̇_return ) with a control target of a vanishing time derivative (ḣ_target = 0) of a temporal progression of a fill level in the level-controlled tank (71).
10. The applicator (10, 100, 102) according to claim 8 or 9, characterized in that a controllable proportional valve (80) and/or a controllable return pump (37) is or are located in the return line (34).
11. The applicator (10, 100, 102) according to one of Claims 8 to 10, characterized in that it includes a plate (60), which can be at least partially inserted in a spray cone (21) generated by the at least one applicator nozzle (22) in order to control a quantity of additive (20) incorporated in the filter material strip (12).
12. The applicator (10, 100, 102) according to one of Claims 8 to 10, characterized in that the supply meter (32) and/or the return meter (36) is or are configured as a volume flow meter or as a tachometer for a pump (33, 37).
13. The applicator (10, 100, 102) according to one of Claims 8 to 10, characterized in that it is configured and set up to carry out a method according to one of Claims 1 to 7.
14. A machine of the tobacco processing industry having an applicator (10, 100, 102) according to one of Claims 8 to 13.
15. The machine according to Claim 14, characterized in that it includes a removal apparatus for removing filter rods cut to length from the filter strand, by means of which filter rods that are insufficiently sprayed can be removed.

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