EP2545213B1 - Method and device for measuring the weight of an endless flow of web-shaped fiber material - Google Patents

Description

The invention relates to a device and a method for processing an endless stream of web-shaped fiber material to a nonwoven web according to the preamble of claim 1 and 6, respectively.

From the DE 10 2007 014 694 A1 For example, a device for transporting a fibrous layer to a carding machine is known. The transport route begins at a Rüttelschachtspeiser, which deposits fibers on a first conveyor belt. About another driven conveyor belt, the fiber layer reaches the circulating conveyor belt of a belt scale and from there to the collection of a card. In the belt weigher there are measuring devices located there, sensors, the determination of the weight of the located on the band of the belt scale fiber layer corresponding signals. The signals are fed to a controller, which processes them in conjunction with speed signals of the carding, such that a uniform, uniform non-woven fabric is formed by the carding.

The fiber layer to be analyzed by the belt weigher with respect to its weight is transferred from a conveyor belt in the previous transport conveyor belt scale, and then from the belt weigher to another, downstream conveyor belt, which serves to feed a card. In the transfer areas, the guide rollers of the corresponding conveyor belts are parallel to each other. In a gore-shaped space, the fiber layer is transferred unsupported from the one to the subsequent conveyor belt. Depending on the fiber thickness, mass of the batt, the structure and composition of the fiber layer distortions arise in the transfer fees, which lead by the consequent stresses to a falsification of the measurement result of the belt scale.

These measurement errors can be compensated by a correction factor. This must be determined and fed to the evaluation device. Since, as indicated, the fiber parameters have a decisive influence on the error value, a separate correction value must be generated for each fiber material, for each mixture, which is complicated especially with frequent material changes.

From the DE 10 2008 022 817 A1 a device for feeding fibers to a textile machine is known, wherein the fibers via a shaft on a circulating conveyor belt trained trigger device are stored. Below the shaft, the weight of the fibers deposited thereon is measured with a first measuring device and controlled according to the transport speed of the conveyor belt. Thus, for example, a downstream opening unit, a constant fiber mass per unit time can be supplied.

This known device has, in addition to the first measuring device in the conveying direction of the fibers behind the shaft, a second measuring device. Due to the nature of the fibers caused by the behavior of the fibers within the shaft or in the filing of the fibers on the conveyor belt can not be determined by the first measuring device, the correct weight. Through the second measuring device in a region in which the fibers have left the shaft, the actual amount of fiber on the belt is measured. This primary and secondary measurement results in a differentiated control of the fiber flow.

The DE 3913733 A1 discloses a weight measurement in front of a card, for example with a belt scale, wherein the weight difference in front of the card between a theoretical and actual weight is determined. The measurement of the mass flow behind the card is not disclosed.

The DE 29909016 U1 shows a measuring device behind the cross-stacker with the goal of profiling. The document does not disclose an upstream belt scale in front of the card.

From the generic EP 0635589 A1 It is known to measure on the belt scale, the basis weight of the incoming fiber mat and enter with the actual belt speed in a controller. Behind the carding machine, the discharge speed of the fiber material is measured. Furthermore, a setpoint for the surface or strip weight at the outlet of the card or at the outlet of a Kreuzlegers is entered into the controller. A predefined correction factor should take into account plant-specific, textile-technological or climatic influences.

After EP 1268896 B1 There is no measurement of the fiber flakes in front of the carding machine, with which the actual mass flow can be determined. While the document generally discloses a basis weight correction in the formation of the pile upstream of the crosslayer, it does not give any concrete instruction as to how to do this and how to form the correction factor. Generally this writing has the goal to influence the profile.

The object of the present invention is to provide an apparatus and a method for processing an endless stream of web-shaped fibrous material into a nonwoven web, in which the control of the speed of the machine processing the fiber material is improved.

This object is achieved by the features of claim 1 and 6, respectively.

According to the invention, a speed sensor and a measuring device are arranged behind the machine processing the fiber material, with which the mass flow of the nonwoven web is determined, wherein an evaluation unit determines a correction value from the mass of the fiber layer over time and the mass flow of the nonwoven web, the calculated from the current, determined by the measuring system of the belt scale measured value of the actual mass value of the fiber layer, with which a controller controls the speed of the fiber material processing machine.

The web-shaped fiber material is a fiber layer, which is deposited by a feeder (Rüttelschachtspeiser, Krempelspeiser) on a first conveyor belt. This fiber layer is then transferred to a second circulating conveyor belt, which forms a belt scale with an associated weight measuring system. Subsequently, a further transfer of the fiber layer to the collection of a card. The pile formed by the carding is laid by a cross-lapper to a fleece of intended thickness.

The output of the cross-stacker is a surface mass, the basis weight of the nonwoven determining measuring device arranged, which operates on a radiometric principle of action. The measuring system is suspended on a transverse to the direction of movement of the nonwoven web traverse and performs during the measurement periodic reciprocating movements across the width of the nonwoven web. As a result, in addition to the weight per unit area, the homogeneity of the nonwoven web as well as density fluctuations can be recognized. Furthermore, the width of the nonwoven web can be determined.

In the example described here, the signals of the surface measuring system and the speed signal output of the cross stacker are used to correct the results of the weight measuring system of the belt scale at the beginning of the carding. Here, the fact is exploited that according to the conservation of mass, the time average of the mass flow (mass per unit time) output of the Kreuzlegers equal to the time average of Mass flow at the beginning of the carding (mass flow over belt scale) is. In theory, the ratio of the mentioned mass flows is equal to one.

The mass flow output of the crosslapper results from the product basis weight, product width and production speed. The web width is hereby continuously determined by the surface measuring system itself, by detecting the signal jumps occurring when passing over the edges of the nonwoven web and processed with the position signals of the measuring head. The production speed is known and is present as a corresponding signal of the control of the card / the crosslapper or is detected with a separate speed sensor.

From the ratio of the mass flow output of the crosslapper and the mass flow at the beginning of the carding can be determined a correction factor, which is used to determine the weight of the located on the belt scale fiber layer. Clearly, a correction factor can be determined by the method according to the invention, which indicates how much the weight value of the fibrous layer in the area of the belt weigher is actually higher or lower than the measured value determined merely by means of a belt weigher.

The present invention also relates to a method of processing an endless stream of web-shaped fibrous material into a nonwoven web, wherein the fibrous material is produced by a feeder in the form of a fibrous layer and processed by a subsequently arranged fibrous material processing machine which is a card and a cross-stacker between the feeder and the fiber material processing machine, the mass of the fiber layer is determined by a belt weigher, wherein a circulating conveyor belt with an associated measuring system forms the belt scale, and is determined behind the fiber material processing machine, the mass flow of the nonwoven web, wherein a Evaluation unit from the mass of the fiber layer over time and the mass flow of the nonwoven web a correction value from the current, determined by means of the measuring system of the belt scale measured value calculates the actual mass value of the fiber layer, with a controller, the speed it controls the fiber material processing machine, wherein the mass flow of the nonwoven web is formed from the speed and the basis weight, and by the measured mass flow after the fiber material processing machine, the results of the belt weigher are corrected.

In addition, the following measures may be provided:

The basis weight or basis weight can be determined by a radiometric measuring principle. Known measuring principles for determining the basis weight use isotope radiation sources such as promethium, krypton or strontium. The radiation passing through the material or radiated back from the material is detected, wherein the basis weight of the nonwoven web can be determined from the intensity of the respective radiation. Depending on the nonwoven material, optical measuring methods can also be used.

The measuring device for determining the weight per unit area can be a measuring head which can be moved transversely to the conveying direction of the fiber material.

The measuring device for determining the basis weight may be a radiometrically operating measuring device.

• Fig. 1 zeigt ein Prinzipbild der erfindungsgemäßen Lösung.
• Fig. 2 eine Draufsicht auf die Förderstrecke nach Figur 1.

Furthermore, the explanation of an embodiment of the invention with reference to the drawings. It shows:

• Fig. 1 shows a schematic diagram of the solution according to the invention.
• Fig. 2 a plan view of the conveyor line after FIG. 1 ,

A Rüttelschachtspeiser RSS generates a web-shaped fiber layer F on a first conveyor belt T1. This first conveyor belt T1 is guided around a deflection roller U1 and, in this area, forwards the fiber layer F to a conveyor belt TBW, which revolves around deflection rollers UA, UB in the direction of the arrow. Parallel to the guide roller UB there is a further guide roller U2, which clamps a further conveyor belt T2. In the region of the guide rollers UB, U2, the fiber layer F is transferred from the conveyor belt TBW to the further conveyor belt T2. This conveyor belt T2 is coupled to a in the drawing only indicated carding KR and feeds them.

Immediately downstream of the carding machine KR is a likewise only indicated cross stacker KL, which places the pile formed by the card into a nonwoven V. The web V has output of the cross-stacker KL at a speed v, which is determined by means of a speed sensor SV. The speed sensor SV is, for example, a measuring roller in contact with the web V, which is connected to an incremental encoder.

About the nonwoven web V extends TraverseT, which carries a measuring head M, by means of which the basis weight of the web V is determined. The measuring head M and the speed sensor SV are in signal communication with an evaluation device A, which has the electronics for evaluating the signals. The electronics of the evaluation device A is also supplied with a signal of the motion control of the measuring head M, so that the movement of the measuring head M detected and in connection with the measurement signals, the width of the nonwoven web V can be determined. In the figures, it is indicated that the signal of the movement control of the measuring head M of the traverse T, which has corresponding drive means, is removed.

The evaluation device A determines from the signal of the measuring head M, the basis weight q of the web V, for example in the unit [kg / m ² ]. Also, by evaluating the motion signal of the measuring head M, the width b of the nonwoven web V is determined - unit [m]. Finally, the speed sensor SV delivers a speed signal which can be converted into a speed value v - unit [m / h].

From the quantities now known, the mass flow rate Δm / Δt in the region of the measuring head M can be determined, that is to say how much mass Δm is conveyed to the fleece V per unit time Δt of the cross-stacker KL. Calculated results thus: $$\mathrm{Dm}/\mathrm{.delta.t}=\mathrm{q}\cdot \mathrm{b}\cdot \mathrm{v}\mathrm{,}$$

The conveyor belt TBW stretched around the guide rollers UA and UB cooperates with a weight sensor GS such that the conveyor belt TBW forms a belt scale. By the weight sensor GS, the load of between the guide rollers UA, UB stretched portion of the conveyor belt TBW is detected - for example, the slack of the tape. Also, the guide rollers UA, UB can be coupled with force measuring devices and thus form the measuring system for the load on the conveyor belt TBW the belt scale. The representation of the weight sensor GS is thus purely a matter of principle.

The weight sensor GS is connected to the evaluation device A, in which the mass of the fiber layer F located on the belt scale is determined from the signal thereof. For reasons already explained, this value, which is recorded exclusively via the belt scale, is subject to errors.

The evaluation device A records the mass value of the fiber layer F determined via the belt weigher over time and forms the one via the belt weigher in the direction of carding KR, Kreuzleger KL current mass flow Δ m / Δ t , ie the mass Δ m fibers per unit time Δ t unit [kg / h].

The comparison of the mass flows results in a correction factor k: $$\mathrm{k}=\mathrm{\Delta }m/\mathrm{\Delta }t/\mathrm{Dm}/\mathrm{.delta.t}\mathrm{,}$$

With this correction value k, the actual mass value of the fiber layer F can be determined from the current measured value determined by means of the sensor system GS of the belt weigher, which is supplied to the controller ST of the drive for the carding machine KR and used for speed control. For this purpose, the evaluation device A is connected to the controller ST of the carding machine KR. The mass value determined in this way can also be displayed on a display of a machine terminal, not shown, via which the values intended for production are set.

FIG. 2 is a representation of the conveyor line after FIG. 1 in a schematic representation from above. It is indicated in particular how the determination of the width b of the nonwoven web by the traversing measuring head, namely by periodically traversing over the entire length of the traverse T - the Meßwertsprünge at the edges of the nonwoven web V in conjunction with the movement signals of the measuring head control to determine the width b evaluated the web.

LIST OF REFERENCE NUMBERS

RSS

Rüttelschachtspeiser

F

fiber layer

T1

first conveyor belt

U1

Deflection roller (first conveyor belt)

T2

second conveyor belt

U2

Deflection roller (second conveyor belt)

TBW

Conveyor belt (belt scale)

UA

Deflection roller (conveyor belt belt scale)

UB

Deflection roller (conveyor belt belt scale)

GS

Weight sensor (belt scale)

A

evaluation

ST

control

KR

stuff

KL

stacker

V

Fleece, nonwoven web

M

Measuring device, measuring head

T

traverse

SV

speed sensor

v

Speed nonwoven web

b

Wide nonwoven web

Claims (6)

1. A device for processing an endless flow of a web-shaped fiber material into a nonwoven web (V), comprising a feeder (RSS) producing the fiber material in the form of a fiber layer (F) that may be fed to a downstream fiber material-processing machine (KR, KL) which is a card (KR) and a cross-lapper (KL), wherein a belt weigher is arranged between the feeder (RSS) and the fiber material-processing machine for measuring the mass of the fiber layer (F), wherein the belt weigher is formed by a continuous conveyor belt (TBW) with an associated measuring system,
   characterized in that
   downstream of the fiber material-processing machine (KR, KL), a velocity sensor (SV) and a measuring device (M) are arranged, by means of which the mass flow of the nonwoven web (V) is determined, wherein an evaluation unit (A) determines a correction value (k) from the mass of the fiber layer (F) over the time and the mass flow of the nonwoven layer (V), which correction value calculates the actual mass value of the fiber layer (F) from the current measuring value determined by means of the measuring system of the belt weigher, with which a control (ST) controls the speed of the fiber material-processing machine (KR, KL).
2. The device of claim 1, characterized in that the measuring system assigned to the belt weigher comprises a weight sensor (GS) for measuring the mass of the fiber layer (F), which cooperates with the conveyor belt (TBW) of the belt weigher stretched around guide rolls (UA, UB) and detects the load on the section of the conveyor belt (TBW) stretched between the guide rolls (UA, UB).
3. The device of claim 2, characterized in that the weight sensor (GS) detects the load on the basis of the sag of the conveyor belt.
4. The device of claim 1, characterized in that the measuring system assigned to the belt weigher for measuring the mass of the fiber layer (F) cooperates with the conveyor belt (TBW) stretched around guide rolls (UA, UB), wherein the guide rolls (UA, UB) are coupled with force measuring devices for measuring the load on the conveyor belt (TBW).
5. The device of one of claims 1 to 4, characterized in that the measuring device at least consists of a measuring head (M) traversing in a direction transversal to the conveying direction of the nonwoven web (V), the measuring head serving to determine the weight per unit area of the nonwoven web (V).
6. A method for processing an endless flow of a web-shaped fiber material into a nonwoven web (V), wherein the fiber material is produced by a feeder (RSS) as a fiber layer (F) and is processed by a downstream fiber material-processing machine (KR, KL) which is a card (KR) and a cross-lapper (KL), wherein the mass of the fiber layer is determined between the feeder (RSS) and the fiber material-processing machine (KR, KL) by means of a belt weigher, wherein the belt weigher is formed by a continuous conveyor belt (TBW) with an associated measuring system,
   characterized in that
   downstream of the fiber material-processing machine (KR, KL), the mass flow of the nonwoven web (V) is determined, wherein an evaluation unit (A) determines a correction value (k) from the mass of the fiber layer (F) over the time and the mass flow of the nonwoven layer (V), which correction value calculates the actual mass value of the fiber layer from the current measuring value determined by means of the measuring system of the belt weigher, with which a control (ST) controls the speed of the fiber material-processing machine (KR, KL), wherein the mass flow of the nonwoven web (V) is formed from the velocity and the weight per unit area, and the results from the belt weigher are corrected based on the measured mass flow downstream of the fiber material-processing machine (KR, KL).

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