EP0365470B1 - Device for attaching the trailing end of a web to the leading end of another web - Google Patents

Description

The present invention relates to a method for connecting the end of a band to the beginning of another band according to the preamble of claim 1.

Such a method is known from FR-A-2 078 354. This method works with a device which comprises an integrator consisting of an operational amplifier and a capacitor. The output of the operational amplifier is connected to the input of a threshold switch which supplies current for a relay which is provided in order to switch off the first drive motor. This device can use a buffer device to compensate for the speed differences that the belt has or can have before and after the buffer device.

From DE-A1-31 43 209 a device for feeding a tape is also known which has two buffer devices for the supply rolls. These buffer devices are located in front of the mechanism for connecting both ends of the tape.

The invention is based on the object of improving a method of the type mentioned at the outset in such a way that a precisely centered splicing is possible, even with high machine output.

This object is achieved according to the invention by a device with the features specified in the characterizing part of patent claim 1.

Further advantageous embodiments of the invention are specified in the dependent claims.

Fig. 1

eine schematische Darstellung einer Verpackungsmaschine mit einer Vorrichtung nach der Erfindung,

Fig. 2

ein Diagramm mit einer ersten Variante für den Geschwindigkeitsverlauf des gesteuerten Motors einer solchen Vorrichtung,

Fig. 3

ein Diagramm zur Veranschaulichung der verschiedenen Längen, die die Bandschleife in einer Puffervorrichtung aufweisen kann nach Massgabe der unterschiedlichen Geschwindigkeit des Bandes vor und nach dieser Puffervorrichtung,

Fig. 4

das Ersatzschaltbild eines Prozessors für den Normalbetrieb der Servoeinrichtungen der erfindungsgemässen Vorrichtung,

Fig. 5

das Ersatzschaltbild des Prozessors für den Spezialbetrieb dieser Servoeinrichtungen während der Zeit, in der das Verbinden der Bänder stattfindet,

Fig. 6

ein Diagramm mit einem anderen Geschwindigkeitsverlauf des gesteuerten Motors einer solchen Vorrichtung, und

Fig. 7

eine schematische Darstellung zur Erläuterung der Arbeitsweise der Vorrichtung, um einen vorgegebenen Markenabstand auf der Verbindungsstelle des Bandes einzuhalten.

The invention is explained in more detail below using exemplary embodiments with reference to the accompanying drawing. In the drawing shows

Fig. 1

1 shows a schematic representation of a packaging machine with a device according to the invention,

Fig. 2

1 shows a diagram with a first variant for the speed profile of the controlled motor of such a device,

Fig. 3

1 shows a diagram to illustrate the different lengths that the belt loop can have in a buffer device in accordance with the different speeds of the belt before and after this buffer device,

Fig. 4

the equivalent circuit diagram of a processor for normal operation of the servo devices of the inventive device,

Fig. 5

the equivalent circuit diagram of the processor for the special operation of these servo devices during the time in which the bands are connected,

Fig. 6

a diagram with another speed curve of the controlled motor of such a device, and

Fig. 7

is a schematic representation for explaining the operation of the device in order to maintain a predetermined mark distance on the connection point of the belt.

The packaging machine according to FIG. 1 is provided with a first supply roll 1, from which a tape or a film 2 is unwound, via a roll system 3, a splicing roll 4, a guide roll 5, a drive roll 6, a film storage roll 7 and two further guide rolls 8 and 9 is fed to a folding box 10 by pulling the film 2 formed into a tube through a roller feed 11. In front of the folding box 10 there is a loading device 12, through which the goods to be packaged are introduced into the film tube, which is closed at regular intervals by a transverse heater 13, at the exit of which an outlet device 14 is provided in order to remove the packaged and closed goods.

The roller feed 11 is driven by the drive or motor 31 of a first servo device 15 and the drive roller 6 by the drive or motor 41 of a second servo device 16 driven. The servo devices 15 and 16 are connected to a processor, not shown in the figure. They can be constructed similarly and each have an amplifier 32 or 42, a tachometer 33 or 43 and an angle sensor 34 or 44.

The packaging machine according to FIG. 1 is also provided with a second supply roll 17, from which a band or a film 18 can be unwound as soon as the supply roll 1 is empty. For this purpose, a splicer device 21 is provided, which presses the splicer rollers 4 and 20 against one another in order to connect the end of the film 2 to the beginning of the film 18, and the film storage roller 7 is movably integrated into a device 22 via a rocker arm 71 to be able to change the length of the film loop. There are also several buttons 23 to 29 provided for various control and monitoring purposes.

von x = 1 bis x = 0 reduziert, so dass im Zeitpunkt π die Folie 2 im Bereich der Spleisserrollen 4 und 20 für einen Moment stillsteht, um ein Verbinden oder Schweissen des Endes der Folie 2 mit dem Anfang der Folie 18 zu erleichtern. Danach wird die Geschwindigkeit x erhöht, um beispielsweise im Zeitpunkt 2π wieder die normierte Geschwindigkeit x = 1 zu haben. Dadurch entsteht eine Wegdifferenz L zwischen den zurückgelegten Strecken der Folie im Teil vor und nach der Antriebsrolle 6, da der untere Teil der Folie mit der konstanten normierten Geschwindigkeit v = 1 weiterläuft. Diese Wegdifferenz L wird durch die bewegliche Folienspeicherrolle 7 aufgenommen, weil durch die Bewegung des Schwinghebels 71 die Länge der unteren Schleife während der Zeit 0 bis 2π (Fig. 2) um den Betrag L kürzer wird. Nach dem Zeitpunkt $\text{t = 2π}$

kann die Geschwindigkeit v der Antriebsrolle 6 beispielsweise auf v = 1,5 für eine weitere Zeit $\text{T = 2π}$

erhöht werden, um die Wegdifferenz L zu kompensieren und die untere Schleife um diesen Betrag L zu verlängern, derart, dass im Zeitpunkt $\text{t = 4π}$

beide Folienteile mit derselben normierten Geschwindigkeit v = 1 abgewickelt werden.The packaging machine according to FIG. 1 works as follows:
The film limit switch 23 detects the point in time at which the end of the film 2 passes a specific point on the roller system and supplies a signal a to the processor which, on the basis of this signal and other parameters, generates a control signal Vas for the servo device 16 by the speed v of the motor 41 normalized according to that in FIG. 2 change function v (t) shown. The speed becomes between the normalized time 0 and π $\text{v (t) = x}$

reduced from x = 1 to x = 0, so that at the point in time π, the film 2 in the area of the splicer rolls 4 and 20 stands still for a moment, in order to make it easier to connect or weld the end of the film 2 to the beginning of the film 18. Then the speed x is increased, for example to have the normalized speed x = 1 again at the time 2π. This creates a path difference L between the distances covered by the film in the part before and after the drive roller 6, since the lower part of the film continues to run at the constant normalized speed v = 1. This path difference L is taken up by the movable film storage roller 7 because the length of the lower loop becomes shorter by the amount L during the time 0 to 2π (FIG. 2) due to the movement of the rocker arm 71. After the time $\text{t = 2π}$

For example, the speed v of the drive roller 6 can be set to v = 1.5 for a further time $\text{T = 2π}$

can be increased to compensate for the path difference L and to extend the lower loop by this amount L in such a way that at the time $\text{t = 4π}$

both film parts are processed at the same standardized speed v = 1.

ist. Im Normalfall sind die Geschwindigkeiten der beiden Teile der Folie gleich. Beim Spleissen wird die Geschwindigkeit $\text{v = x}$

des oberen Folienteils derart reduziert, dass dessen zurückgelegte Strecke Sx ist. Aus Fig. 3 ist die Konstanz der Funktion Sx(t) im Punkt $\text{t = π}$

entsprechend dem bewirkten Stillstand ersichtlich.The straight line S in FIG. 3 illustrates a distance traveled from the lower part of the film 1, due to the normalization $\text{S = t}$

is. Usually the speeds are the two Parts of the film the same. When splicing, the speed $\text{v = x}$

of the upper film part is reduced in such a way that its distance covered is Sx. From Fig. 3 is the constancy of the function Sx (t) in the point $\text{t = π}$

according to the standstill caused.

für die normierte Geschwindigkeit angenommen (Fig. 2). Daraus ergibt sich für die Strecke Sx durch Integration $$\begin{gathered} \text{Sx = ∫x.dt = ∫(1 + cos t)/2.dt =} \\ \text{= 0,5.t + 0,5.sin t} \end{gathered}$$

gültig im Bereich 0 bis 2π.The function is an example $$\text{x = (1 + cos t) / 2 = v (t)}$$

assumed for the normalized speed (Fig. 2). For the route Sx this results from integration $$\begin{gathered} \text{Sx = ∫x.dt = ∫ (1 + cos t) /2.dt =} \\ \text{= 0.5.t + 0.5.sin t} \end{gathered}$$

valid in the range 0 to 2π.

For t = 2π, Sx = π (point A) applies.

so dass für t = 4π gilt S′x = 3π (Punkt B).The function v = 1.5 (constant) applies in the range 2π to 4π. For the route Sx this results from integration $$\text{S′x = ∫1.5.dt = 1.5 t}$$

so that for t = 4π, S′x = 3π (point B).

Of course, completely different functions for the speed v can also be selected, which bring the film to a standstill for a short time.

die Flächen F1 und F2 in Fig. 2 gleich sind, das heisst $\text{F1 = F2}$

.It should also be noted that because of $$\int_{\text{O}}^{\text{2π}} \text{(1 - x) German}\,d \text{= 0.5. ∫ (1 - cos t) dt = π}$$

the areas F1 and F2 in FIG. 2 are the same, that is $\text{F1 = F2}$

.

Whs

= Soll-Verschiebung des Schwinghebels 71 der Vorrichtung 22,

v

= Ist-Geschwindigkeit der Folie beim Rollenvorschub 31,

va

= Ist-Geschwindigkeit der Folie beim Antrieb 41 (Fig. 1),

vh

= äquivalente Ist-Geschwindigkeitskomponente der Folie bei Winkeländerungen des Schwinghebels,

wh

= Ist-Verschiebung des Schwinghebels 71,

Vas

= Soll-Geschwindigkeit der Folie beim Antrieb 41.

4 shows the equivalent circuit diagram 45 of the processor for the normal operation of the servo devices 15 (master) and 16 (slave). In this figure, the signals v, Whs, va, vh, wh and Vas have the following meaning:

Whs

= Target displacement of the rocker arm 71 of the device 22,

v

= Actual speed of the film at roll feed 31,

especially

= Actual speed of the film in drive 41 (FIG. 1),

vh

= equivalent actual speed component of the film when the rocker arm changes in angle,

wh

= Actual displacement of the rocker arm 71,

Vas

= Target speed of the film for drive 41.

bildet, worin p ein Parameter und dh das Ausgangssignal eines weiteren Subtrahierers 46 ist, in dem die Differenz $\text{dh = wh - Whs}$

gebildet wird.The processor performs the following operations: The output signal v of the servo device 15 is fed to a subtractor 47, which is the difference $\text{Vas = vp.dh}$

forms, where p is a parameter and ie the output signal of a further subtractor 46, in which the difference $\text{dh = wh - Whs}$

is formed.

eines weiteren Subtrahierers 48 beaufschlagt wird, der das Signal va von der Servoeinrichtung 16 (Slave) erhält, die ihrerseits vom Signal Vas gesteuert wird.The signal wh is supplied by an integrator 49, which has the output signal on the input side $\text{vh = va - v}$

a further subtractor 48 is applied, which receives the signal va from the servo device 16 (slave), which in turn is controlled by the signal Vas.

Daraus ergibt sich, dass ein Stillstand der Vorrichtung 41 möglich ist, weil für Vas = 0 die Maschine weiter funktionieren kann, auch wenn v verschieden von null ist. In dieser Gleichung sind p und q Parameter mit der Dimension s⁻¹.The following therefore applies: $$\text{Vas = -q. ∫ (va - v) dt + v + p.Whs.}$$

It follows from this that the device 41 can stand still because the machine can continue to function for Vas = 0, even if v is different from zero. In this equation, p and q are parameters with the dimension s⁻¹.

Was

= Soll-Winkel des Antriebs 41

wa

= Ist-Winkel des Antriebs 41

wr

= Ist-Winkel des Antriebs 31.

5 shows the equivalent circuit diagram of the processor for the special case of speed reduction for the splicing process. In this figure, the additional signals What, wa and wr have the following meaning:

What

= Target angle of drive 41

wa

= Actual angle of drive 41

wr

= Actual angle of drive 31.

zu bilden, wobei das Signal wa von der Servoeinrichtung 16 geliefert wird. In einer Addierschaltung 55 wird die Summe des Signals da und des Ausgangssignals V′as eines Multiplizierers 52 gebildet, in dem eine Multiplikation der Ausgangssignale z und v der Schaltung 51 bzw. der Vorrichtung 15 stattfindet. Das Ausgangssignal Vas der Schaltung 55 wird der Vorrichtung 16 zugeführt, die auch das Signal va liefert.The processor causes the following operations to be performed:
The output signal wr of the servo device 15 is supplied to both a speed correction circuit 51 and a phase correction circuit 53, with their output signal As for a subtractor 54, the difference $\text{da = what - wa}$

to form, the signal wa being supplied by the servo device 16. The sum of the signal da and the output signal V'as of a multiplier 52 is formed in an adding circuit 55, in which the output signals z and v of the circuit 51 and the device 15 are multiplied. The output signal Vas of the circuit 55 is fed to the device 16, which also supplies the signal va.

mit $\text{v = x}$

.So it applies $$\text{Vas = What - wa + vz}$$

With $\text{v = x}$

.

(vgl. Fig. 3) bzw. in $\text{z = g.x}$

(vgl. Fig. 2), worin f und g Parameter sind.Circuits 53 and 51 transform signal wr into $\text{What = f.Sx}$

(see Fig. 3) or in $\text{z = gx}$

(see Fig. 2), where f and g are parameters.

und da bei $\text{t + Δt = π + Δt}$

einerseits $\text{1 + cos t ≅ 0}$

und andererseits $\text{sin t ≅ - Δt}$

ist, resultiert für $\text{t ≅ π}$

$$\text{Vas = 0,5.f.(π + Δt - Δt) - wa.}$$

This results in $${\text{Vas = f.0.5. (T + sin t) - wa + g.0.25. (1 + cos t)}}^{\text{2nd}}$$

And thereby $\text{t + Δt = π + Δt}$

on the one hand $\text{1 + cos t ≅ 0}$

and on the other hand $\text{sin t ≅ - Δt}$

is results for $\text{t ≅ π}$

$$\text{Vas = 0.5.f. (Π + Δt - Δt) - wa.}$$

die Soll-Geschwindigkeit der Folie beim Antrieb 41 null ist.This means that for $\text{2.wa = f.π}$

the target speed of the film in drive 41 is zero.

FIG. 6 shows that the function v (t) is determined at the discretion and the speed v can also be kept equal to zero for a predetermined time GH.

worin LR ein Sicherheitssummand ist, mit dem man den Fall berücksichtigen möchte, dass die Folie 2 am Ende einen Riss aufweist. Dabei wird der Summand LR nach Ermessen, beispielsweise kleiner als ein Markenabschnitt gewählt.In FIG. 7 the elements 2, 4, 20, 23 and 27 of FIG. 1 are again shown schematically and some marks of the film 2 are numbered 0, 1, 2, ... 10. The distance LV between the sensor point A of the membrane switch 23 and the splice point B between the splice rollers 4 and 20 and the distance LM between the point B and the sensor point C of the button 27 is given by the geometry of the system. The button 23 therefore recognizes the end of the film at point A and accordingly emits the signal a. The button 27 constantly monitors the marks and generates a signal b each time a mark passes. With the aid of signals a and b, the processor determines the distance LX between mark 8 and point C when the end of film 2 is at point A; the processor also calculates the route $$\text{x = LX + LV + LM - LR}$$

where LR is a security summand with which one would like to take into account the case that the film 2 has a crack at the end. The summand LR is chosen at discretion, for example smaller than a brand section.

The processor first determines the number of entire mark sections on the path x defined in this way, which gives the current position of mark 1; it then calculates both the number of marks up to the start of the speed reduction and the corresponding phase shift of the motor 41, which is done with the aid of the signal va (FIG. 1), as well as the number of marks up to the splice torque and the corresponding phase shift of the motor 41. Im 7 there are two marks 6 and 7 until the start of the speed reduction and two whole marks 4 and 5 until the start of the splicing period. In Fig. 7, the distance DB corresponds to two and a half mark sections, for example, and the speed reduction begins when the mark 1 passes the point D. The splicing moment at which the end of the prepared film 18 (FIG. 1) is connected to the leading end of the old film 2 corresponds to the passage of the mark 1 at point B, at which the speed of the film is zero for a moment .

An advantage of this method is that only one reference point is required for different formats. In addition, this process results in a defined, controlled lowering movement that enables precisely centered splicing, even with high machine output.

The splicing according to this method can also be set such that the trigger length is determined by determining the distance between two centering marks, which can be carried out, for example, by the interaction of an optical button and an incremental encoder, a trigger length corresponding to the centering mark distance.

Finally, it should also be noted that the first and / or the second motor can be DC servomotors with a tachometer generator and incremental encoder, as well as AC servomotors with a resolver, for example, which are very dynamic and provide information about the absolute angle. Other drives can also be used otherwise. It should also be taken into account that the integration, which is carried out by the integrator 49 of the equivalent circuit diagram according to FIG. 4, or the subtraction, which is carried out by the subtractor 48, actually takes place physically in the device 22.

Claims (9)

1. Device for connecting the trailing end of one web to the leading end of another web, with a first drive (31) for the web (2) extending from supply roll (1), with a second drive (41) to support the movement of the web (2), with a further supply roll (17) for the web to be connected, with a first buffer device (22) to compensate for the differences in speed which are or may be present in the web (2) before and after the buffer device (22), with an integrator (49), with a further buffer device (3, 19) for each of the supply rolls (1; 17) and with a mechanism (4, 20) for connecting the two web ends and wherein the device is formed to reduce the speed of the web to nil when two web ends are to be connected, characterised in that the first drive (31) is integrated into a first servomechanism (15) and the second drive (41) is integrated into a second servomechanism (16), wherein both servomechanisms (15; 16) are connected to a computer, and in that the second servomechanism (16) receives a control signal Vas from the computer, for which, in normal operation, ie when the two web ends have been connected, the formula $$\text{Vas = v + p.Whs - q . ∫ (va-v)dt}$$

   

   is true, wherein t is a time, Whs is an equivalent desired enlargement of the web loop of the first buffer device (22), va is the web speed effected by the second drive (41) and v is the actual speed of the web with the first drive (31), and wherein p and q are parameters.
2. Device according to claim 1, characterised in that in order to control the second servomechanism (16) in special operation, ie during the process of connecting the two web ends, the computer gives out a signal for which the formula $${\text{Vas = f. ∫ v.dt - wa + g.v}}^{\text{2}}$$

   

   is true, in such a way that at the moment of connection of the two web ends v = 0, and wherein wa is a signal which represents the momentary actual angle of the second drive (41), and wherein f and g are parameters.
3. Device according to claim 1 or 2, characterised in that in special operation the computer operates in accordance with an equivalent circuit, which comprises a speed correction circuit (51), a phase correction circuit (53), a multiplier (52), an adding circuit (55) and a subtracter (54) to carry out the following operations:

   a) an actual angle signal wr of the first servomechanism (15) is supplied to the phase correction circuit (53), of which the output signal Was acts upon the subtracter (54) to form the difference $\text{da = Was - wa}$

   

   ,

   b) the actual angle signal wr of the first servomechanism (15) is also supplied to the speed correction circuit (51), of which the output signal z is multiplied in the multiplier (52) with the first output signal v of the first servomechanism (15) to form an output signal V'as which is added in the adding circuit (55) to the signal da, and

   c) the output signal Vas of the adding circuit (55) is supplied to the second servomechanism (16) to cause a reduction in the web speed to nil.
4. Device according to one of claims 1 to 3, characterised in that in normal operation the process operates in accordance with a second equivalent circuit to carry out the following operations:

   a) the output signal v of the first servomechanism (15) is supplied to a first subtracter (47) which forms the difference $\text{Vas = v - p.dh}$

   

   , wherein p is a parameter and dh is the output signal of a second subtracter (46), wherein the difference $\text{dh = wh - Whs}$

   

   is formed, wherein the signal wh is given out by an integrator (49),

   b) the integrator (49) is acted upon on the input side by the output signal vh of a third subtracter (48), which forms the difference signal $\text{vh = va - v}$

   

   , and

   c) the output signal Vas is used as a control signal for the second servomechanism (16) in normal operation.
5. Device according to one of claims 2 to 4, characterised in that the first buffer device (22) is controlled only during normal operation.
6. Device according to one of claims 1 to 5, characterised in that a mark sensor (27) is disposed between the mechanism (4, 20) for connecting the two web ends and a roller (6) driven by the second drive (41).
7. Device according to claim 6, characterised in that for each supply roll (1; 17) a sensor (23; 24) is disposed to detect the end of the respective web.
8. Device according to claim 6, characterised in that, seen in the advancing direction of the web at least one further sensor (28, 29) is provided downstream of the first buffer device (22).
9. Device according to one of claims 6 to 8, characterised in that the sensors are optical sensors.

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