WO2009039672A1

WO2009039672A1 - Device and method for measuring the winding weight or winding thickness at the inlet of a carding machine

Info

Publication number: WO2009039672A1
Application number: PCT/CH2008/000361
Authority: WO
Inventors: François BAECHLER
Original assignee: Uster Technologies Ag
Priority date: 2007-09-26
Filing date: 2008-08-26
Publication date: 2009-04-02
Also published as: CN101809210A; CN101809210B

Abstract

The device (10) for measuring the weight or thickness of a moved lap (5) comprises a stationary, rigid feed table (4) for guiding the lap (5). The lap (5) is compressed in a measuring gap (8) delimited by the feed table (4) and a feed roller (1). In the region of the measuring gap (8), a plurality of probes (7) are recessed into the feed table (4), the probes being disposed in different locations (y) along the width of the feed table (4) and being independent from each other. Each probe (7) is associated with a force sensor (19) without displacement for generating an electric signal, which is a measure of the weight or thickness of the lap (5) at the location of the respective probe (7). The device (10) has a high measurement resolution and measuring accuracy, high dynamics and a short measurement length. It can be used for the web control of a carding machine according to the principle of open-loop control.

Description

DEVICE AND METHOD FOR MEASURING THE WRAP OR THICKNESS THROUGH THE INFLUENCE OF A CARDE

AREA OF EXPERTISE

The present invention is in the field of spinning preparation and is preferably used for belt regulation of an open-loop card. It relates to an apparatus and a method for measuring the mass or thickness of a moving coil, according to the preambles of the independent claims.

STATE OF THE ART

In the Vorwerk spinning mill, after their dissolution and cleaning, cotton fibers are mixed to form a nonwoven, a wadding or, generally, a fiber structure, which are collectively referred to as wraps. In the carding machine, the cotton flakes that make up the reel are separated to the single fiber, and the fibers are arranged longitudinally. This creates a coherent sliver from which yarn can be spun later. To obtain high-quality yarn, the roll must already be fed into the carding machine as evenly as possible, ie. H. the winding mass fed in per unit time should be constant. For this purpose, it is known to continuously measure the winding mass or winding thickness and to control the feed speed of the coil in an open loop with the measurement signal.

Nowadays, generic devices that incorporate a two-way roller measuring system are widely used. Therein a feed roller of the card serves as inlet measuring element for the winding thickness. The incoming winding is guided between the feed roller and a feed table. The feed roller extends over the entire width of a dining table and is movably suspended at both ends. She pushes the wrap by its own weight, by springs in the suspensions can be additionally strengthened, against the dining table. Thickness variations of the roll cause changes in the pitch and inclination of the feed roll with respect to the feed table. These changes are measured by two Wegaufhehmer, which are each mounted in the suspensions of the feed roller. It is assumed that the winding mass is proportional to the winding thickness. The signals of the two Wegehhehmer be used for the control of the feed speed, whereby an open loop is formed. However, such devices have several disadvantages. The measurement resolution along the width of the roll is limited due to the rigid roll: a single thick spot in the middle of the roll gives the same signal as a thickening along the entire winding width. Furthermore, the measurement is very significant because of the large mass of the feed roller. The measuring field is not clearly defined and has a relatively large length in the direction of travel, so that short fluctuations in the winding thickness can not be detected and the control is insufficient. The measurement is also affected by disturbing influences such as the chain drive system of the feed roller.

In order to improve the measurement resolution, EP-0'467'117 Al proposes several measuring rolls arranged along the winding width. In each measuring roller, an electrical measuring device for detecting the position of the respective measuring roller is present. As a result, the width of the roll is divided into sectors in which the winding thickness is measured independently. However, this is costly and expensive. The measuring field is also not clearly defined in this solution and has a relatively large length.

According to WO-97/36031 A1, the teaching of EP-0'467'117 A1 is simplified in that the deflection signals of all measuring rollers are added to a mechanical transmission element, for example a cable, and fed to a single, common displacement measuring system. This produces a signal that corresponds to the mean thickness of the coil. But even such a device has a complex, fault-prone mechanical structure.

The US-4,785,505 A discloses a generic device in which the feed roller is arranged stationary, but a partial surface of the dining table as

Inlet measuring device for the winding thickness is used. The partial surface is designed as a measuring bar which extends over the entire width of the dining table. The measuring beam is movably suspended at its ends. This results in an analogy to the device with movably suspended feed roller. Thickness variations of the coil cause changes in the pitch and inclination of the measuring beam with respect to the feed roller. These changes are measured by Wegauthehmer. Analogous are the disadvantages of the low measurement resolution and the large inertia.

These disadvantages are partially addressed by US 4,881,415 A. According to their teaching, a plurality of juxtaposed measuring tongues are present, which are pivotable independently of one another in the direction of the feed roller and away from it. The pivotal movements of each tongue are detected by a Wegauthehmer assigned to it. The disadvantage of this device is that at different deflections of two adjacent Meßzungen a gap between the Meßzungen arises in the parts of the roll, so cotton fibers and cotton flakes are trapped. This leads over time to contamination, which affects the proper functioning of the device. The cleaning work required to eliminate the fault leads to undesired shutdowns of the system.

According to US Pat. No. 4,817,247 A, the dining table has openings through which adjacent measuring elements extend. Each measuring element is equipped with a movable sensing element, which in turn is connected to a Wegaufhehmer. Also, this device has the disadvantage of contamination by hanging on the openings cotton flakes and block the movements of the sensing elements.

PRESENTATION OF THE INVENTION

It is an object of the present invention to provide an apparatus and a method for measuring the winding mass, which avoid the above disadvantages. In particular, contamination by trapped wrapping material should be avoided. In addition, a high spatial resolution in the winding width, a low inertia, a short clearly defined measuring field and a more effective control should be achieved. These and other objects are achieved by the device according to the invention and the method according to the invention, as defined in the independent patent claims. Advantageous embodiments are specified in the dependent claims.

The invention is based on the idea to use a virtually trackless force sensor for measuring the mass or thickness of a moving coil. "Virtually weglos" in this document means that the stroke of a sensor connected to the sensor, which is in mechanical contact with the winding, is small in comparison with a height of a measuring gap in which the winding is compressed ten times smaller than the measuring gap height, so that there are no hollows in the feed table, in which wrapping material can remain hanging.The surfaces of the probes are preferably arranged substantially flush with the guide surface of the dining table.

Accordingly, the inventive device for measuring the mass or thickness of a moving coil includes a measuring gap for receiving the coil and a mounted in the region of the measuring gap scanning, which is designed for mechanical contact with the winding and at least one force sensor for outputting an electrical signal, the is a measure of a mass or thickness of the coil.

In a preferred embodiment, the device according to the invention has a fixed dining table with a guide surface for guiding the roll. The measuring gap extends over a width of the dining table. The guide surface of the dining table is rigid at least in the region of the measuring gap. The scanning device includes at least two arranged at different locations along the width of the dining table, inserted into the dining table, mutually independent buttons. Each probe is associated with at least one force sensor for generating an electrical signal that is a measure of the mass or thickness of the coil at the location of the respective button. It is advantageous to provide the device according to the invention with guide elements which feed the entire wrapping material past dead points to the buttons. The device according to the invention is preferably used for the belt regulation of a card according to the open-loop principle. For this purpose, z. B. an output signal of the device for controlling the feed speed can be used.

In the method according to the invention for measuring the mass or thickness of a moving winding, the winding is mechanically scanned. In this case, a force exerted by the winding force is scanned practically weglos. From the scan at least one electrical signal is derived, which is a measure of a mass or thickness of the coil. Preferably, the winding is fed to a measuring gap extending over a width of the roll. The scanning takes place in the region of the measuring gap. The reel is scanned in at least two different locations along its width in independent scans. The scanning operations are carried out by means of a key embedded in a rigid base. From each scan, an electrical signal, which is a measure of the mass or thickness of the roll at the location of the particular scan, is generated.

The at least one electrical signal can be used to control the feed speed of the coil. From the at least one electrical signal and quality characteristics of the coil as the uniformity in width and / or in the longitudinal direction (direction) can be obtained.

The use of a virtually trackless force sensor to measure the mass or thickness of a moving coil may seem disadvantageous at first glance, because commercial force sensors have non-linear signal characteristics. The electrical output signal of a force sensor is typically a power function (eg, a quadratic function) of the winding thickness. However, this signal characteristic can be retroactively linearized in a digital signal processing step. For linearization, either a characteristic typical for the respective sensor type can be used, or an individual characteristic can be recorded for each individual force sensor. The characteristic is z. B. stored in the form of a table, preferably in an evaluation unit of the device or in a local Sensorauswerteeinheit. In particular, the invention offers the following advantages over the prior art:

• Thanks to the scanning by trackless force sensors, the guide surface that guides the winding remains flat. It will create no troughs or projections, which could hang wrapping material.

• Measurement resolution and measurement accuracy are significantly improved by multiple measurements along the winding width.

• The practically smooth measuring device without hysteresis increases the measuring accuracy. • The measuring device is no longer influenced by the drive of the feed roller.

• An increased dynamics of the measuring device is achieved by a much smaller inertia of the moving parts.

• A shorter measuring length, for example with a probe of only 12 mm length in the longitudinal direction, can detect shorter fluctuations in the winding thickness. As a result, a significant improvement in the control action of the open loop is achieved.

• The measuring location or measuring position with respect to the control location is now clearly defined. Thus, the parameters of the regulation can be precisely adjusted for optimum open-loop behavior.

TITLE OF DRAWINGS

Hereinafter, advantageous embodiments of the invention will be explained in detail with reference to the schematic drawings.

Figure 1 shows an embodiment of the inventive device (a) in a schematic side view, (b) in a plan view from the direction Ib-Ib and

(c) in a frontal view from the direction of Ic-Ic. Figure 2 shows a scanning unit for a device according to the invention (a) in a longitudinal section, (b) in a plan view, (c) in a plan view and disclosed

(d) in a cross section.

Figure 3 shows the scanning unit of Fig. 2 in the installed state in a cross section. EMBODIMENT OF THE INVENTION

FIG. 1 shows a first embodiment of the device 10 according to the invention. The device 10 serves to measure the mass or thickness of a moving along a longitudinal direction x 5, the z. B. may be formed as a fleece or cotton wool. It is typically located at the inlet of a carding machine, of which a feed roller 1 and a licker-in 3 are shown. (The feed roller 1 is shown transparent in the plan view of Figure 1 (b) to provide a view of the underlying elements.) The device 10 comprises a stationary, rigid feed table 4 for guiding the roll 5. The driven for rotation feed roller 1 feeds the winding 5 in the card. The feed roller 1 extends substantially over the entire width (in the direction y) of the feed table 4. An axis 2 of the feed roller 1 is fixed with respect to the feed table 4 and so spaced from a winding 5 leading surface of the feed table 4 that between a Jacket surface of the feed roller 1 and the guide surface of the feed table 4, a measuring gap 8 for receiving the roll 5 is formed, in which the winding 5 is compressed. The measuring gap height (in the direction z) is preferably constant along the width (in the direction y) of the feed table 4.

In the region of the measuring gap 8, a scanning device is mounted. The scanner includes several, at different locations along the width (in direction y) of the

Dining table 4 arranged, mutually independent buttons 7. Each button 7 is z. B. formed as in a corresponding opening 6 in the dining table 4 embedded beam whose surface is substantially flush with the Führungsoberfläclie the dining table 4. The shape of the button surface is z. B. rectangular, the side length in the direction of movement x of the roll 5 is preferably as small as possible, so that the measuring field is well defined, and the side length transverse to the direction of movement x (in the direction y) is as large as possible to measure the entire winding width. The number of buttons 7 is preferably at least two and can be arbitrarily large within the technically feasible and meaningful; in the embodiment of Figure 1, it is eight. The greater the number of buttons 7, the higher the resolution and the accuracy of the device 10. The winding mass is determined by the measurement of the winding thickness. Each button 7 is in mechanical contact with the winding 5 and is of this with a force down (ie away from the feed roller 1, in direction -z) pressed, which is the greater, the greater the winding thickness.

Each button 7 is at least one power sensor 19 for generating an electrical signal, which is a measure of the mass or thickness of the coil 5 at the location of the respective button 7, assigned. The at least one associated Kraftensor 19 is operatively connected to the button 7. The compression forces caused by the thickness changes of the roll 5 act on the button 7 and are transmitted to the at least one force sensor 19 associated with the button 7. All force sensors 19 may, for. B. be mounted on a support beam 16, which in turn is mounted on the dining table 4. As force sensors 19 z. B. Rugaufnehmer the type UlA the company Hottinger Baldwin Messtechnik GmbH, D-64293 Darmstadt, Germany, are used. These are strain gauges (strain gauges) based on the piezoresistive effect. Alternatively, piezoelectric, capacitive or voltage-optical force sensors could also be used. The electrical output signal of a force sensor 19 is essentially a power function of the winding thickness. This signal characteristic can be retroactively linearized. In the exemplary embodiment of FIG. 1, two force sensors 19 are associated with each push-button 7, one force sensor 19 being assigned to two adjacent push-buttons 7 at the same time; however, this is not mandatory.

The winding 5 is compressed in the measuring gap 8. The force sensors 19 measure the compression forces exerted by the winding 5 virtually weglos. Therefore, it is possible and recommended, they firmly, z. B. on the support beam 16, and to seal the resulting when entering the button 7 in the dining table 4 joints with sealing material, eg. With silicone seal. Thus, not only a snagging of wrapping material 5 is avoided, but also prevents penetration of wrapping material 5 and other unwanted dirt particles under the guide surface of the feed table 4 and the force sensor 19.

An electrical output signal of the at least one force sensor 19 is on a

Line 17 output. The analog electrical signals of all force sensors 19 can be processed in various ways to form an output signal of the device 10 according to the invention, preferably linked together. This includes the Device 10 preferably a (not shown) evaluation circuit. In a first variant, the sensor signals can be fed together to a summation element which outputs a single sum output signal. In a second variant, each sensor signal can be converted individually into a digital signal and the digital signals are fed to a digital arithmetic unit which, for example, linearises and / or sums them. Other analog or digital combinations of the sensor signals are possible, for example a weighted sum or averaging. Of course, the individual sensor signals and / or the processed output signal processed in other ways, for. B. filtered. The processed output signal is preferably used to control the pull-in speed of the coil 5. For this purpose, the processed output signal can be fed to a controller of an open loop, which in turn regulates the rotational speed of the feed roller 1.

Without special measures 7 dead spots 11 would exist between the adjacent buttons. Wrapping material 5, which would pass between the buttons 7 and past them, the measurement is omitted. This disadvantage avoids the embodiment according to FIG. 1 in that it is additionally equipped with guide elements 18 for the winding 5. The guide elements 18 are z. B. formed as a narrow, elongated, projecting into the height webs and arranged on the dining table 4 in front of the scanning device. Their main task is to supply the entire wrapping material 5 to the buttons 7, so that the template of the card is measured to 100% and avoid dead spots 11.

FIG. 2 shows a scanning unit 20, as can be used in a preferred embodiment of the device 10 according to the invention. The scanning unit 20 includes a bar-shaped button 27 which is in mechanical contact with the winding 5 (see FIG. 1 (a)) and serves to receive compression forces exerted by the winding 5. The compression forces are transmitted to at least one force sensor 29 by means of force transmission elements 23, for example four screws or bolts.

In the embodiment of Figure 2, the scanning unit includes two force sensors 29 which are symmetrically positioned at one end of the elongate scanning unit 20. Each force sensor 29 absorbs the pressure forces from the end of the pushbutton 27 located above it. To absorb the pressure forces of the force sensor 29 includes a T-shaped, preferably made of metal tongue 24, press on the two transverse arms each two power transmission elements 23. The longitudinal arm of the T-shaped tongue 24 is bent at a force, so that its upper side expands. The elongation is measured by means of one or more strain gauges 28. The

Strain gauges 28 are preferably mounted in a connection area between the tongue 24 and a sensor substrate 25. The sensor substrate 25 may, for. B. by means of two sensor mounting screws 26 may be attached to a sensor housing 21.

The output signals of the two force sensors 29 are connected via output lines 31, z. B. ribbon cable, a local Sensorauswerteschaltung 32 supplied. The sensor evaluation circuit 32 may include, in addition to other circuit components, amplifiers for the sensor output signals with adjustment possibilities. It can be constructed on a printed circuit board, which is secured by means of second circuit mounting screws 33 on the sensor housing 21. Components of the sensor evaluation circuit 32 and / or the sensors 29, which are sensitive to moisture or contamination, can be poured into a suitable insulating material and thus protected. Output signals of the sensor evaluation circuit 32 can be conducted to the central evaluation unit via a sensor connection plug-in connector 34, which is accessible via an opening 35 on the underside of the sensor housing 21.

The sensor housing 21 may, for. B. made of metal. It is parallelepiped with, for example, the following masses: length (in x-direction) 15 mm, width (in y-direction) 125 mm, height (in z-direction) 11 mm. The upper surface of the cuboid is missing. It is replaced by the button 27. Joints between the button 27 and the sensor housing 21 are preferably sealed with a sealing ring 22 to prevent ingress of dirt and moisture into the interior of the sensor housing 21.

FIG. 3 shows an advantageous arrangement of the scanning unit 20 of FIG. 2 in a dining table 4 of a card. This representation corresponds to that of Figure l (a); the (not shown here, see Fig. L (a)) winding 5 is thus fed from the left. The measuring gap 8 between the dining table 4 and the feed roller 1 has a height of a few millimeters, z. B. 1-5 mm and preferably about 3 mm. The height of the Measuring gap 8 is preferably variable. By changing the measuring gap height, the operating point of the scanning device 20 can be adjusted. The stroke of the probe 27 is in the tenth of a millimeter range, that is at least ten times smaller than the height of the measuring gap. 8

In the exemplary embodiment of FIG. 3, the sensor housings 21 of the individual scanning units 20 are embedded in a groove 42 which extends transversely (in the y-direction) substantially over the entire width of the feed table 4. It can z. B. eight scanning units 20 may be provided with two sensors 29 each. Under the sensor housings 21 is a cable channel 42 for signal and energy transmission.

Of course, the present invention is not limited to the embodiments discussed above. For the sake of simplicity, in the embodiments discussed above, the dining table 4 has been illustrated as a support for the winding 5. Alternatively, the dining table 4 but could also be above or to the side of the roll 5 and serve to guide it. For this reason, terms such as "above", "below" or "underlay" are not to be understood as limiting in this document With the knowledge of the invention, the person skilled in the art will be able to derive further variants, which also form part of the present invention.

LIST OF REFERENCE NUMBERS

1 feed roller

2 axis of the feed roller

3 lapses

4 dining table

5 wraps

6 opening in the dining table

7, 27 buttons

8 measuring gap

10 device

11 dead spots

16 support beams

17 sensor output line

18 guide element

19, 29 force sensor

20 scanning unit

21 sensor housing

22 sealing ring

23 Rraftübertragungselemente

24 sensor tongue

25 sensor substrate

26 sensor mounting screws

28 strain gauges

31 output lines

32 local sensor evaluation circuit

33 circuit fixing screws

34 Sensor connection plug

35 Opening in the underside of the sensor housing

Claims

1. Use of a force sensor (19) for measuring the mass or thickness of a moving coil (5).

2. Device (10) for measuring the mass or thickness of a moving coil (5), with a measuring gap (8) for receiving the roll (5) and in the region of the measuring gap (8) mounted scanning device, for mechanical contact with the winding (5) is formed and at least one

Sensor (19) for outputting an electrical signal which is a measure of a mass or thickness of the roll (5), characterized in that the at least one sensor (19) is a force sensor.

3. Device (10) according to claim 2, wherein the force sensor (19) includes a strain gauge, which is preferably based on a piezoresistive, a piezoelectric, a capacitive or a voltage-optical measuring principle.

4. Device (10) according to any one of claims 2-4, wherein the device comprises a stationary dining table (4) with a guide surface for guiding the roll (5), the measuring gap (8) extends over a width of the feed table (4) , the guide surface of the feed table (4) is rigid at least in the region of the measuring gap (8), the scanning device at least two at different locations (y) along the width of the feed table (4) arranged in the dining table (4) embedded, mutually independent buttons (7), and associated with each push-button (7) is at least one force sensor (19) for generating an electrical signal which is a measure of the mass or thickness of the roll (5) at the location of the respective push-button (7).

5. Device (10) according to claim 4, wherein the surfaces of the buttons (7) with the guide surface of the feed table (4) are substantially flush.

6. Device (10) according to claim 4 or 5, wherein the scanning device is virtually weglos works and joints in the edge regions of the probe (7) with sealing material (22) are sealed.

7. Device (10) according to any one of claims 4-6, wherein the device (10).

Guiding elements (18) which feed the wrapping material (5) to the buttons (7).

8. Device (10) according to claim 7, wherein the guide elements (18) as a narrow, elongated, projecting in height webs and arranged in front of the scanning device on the dining table (4).

9. Device (10) according to any one of claims 2-8, wherein the scanning device includes at least two force sensors (19) and the device (10) comprises an evaluation circuit for linking the electrical signals of the at least two

Force sensors (19), preferably for forming a sum of the electrical signals comprises.

10. Device (10) according to any one of claims 2-9, wherein the measuring gap (8) on the one hand by a stationary dining table (4) and on the other hand by a driven for rotation feed roller (1) is formed.

11. Use of the device (10) according to any one of claims 2-10 for the belt regulation of a carding machine on the principle of the open loop.

12. A method for measuring the mass or thickness of a moving roll (5), wherein the winding (5) is scanned mechanically and from the sampling at least one electrical signal is derived, which is a measure of a mass or thickness of the roll (5) , characterized in that a force exerted by the winding (5) force is scanned virtually weglos.

13. Method according to claim 12, wherein the winding (5) is fed to a measuring gap (8) extending over a width of the roll (5), the scanning takes place in the region of the measuring gap (8), the winding (5) at least two scanned across its width in independent scanning operations, the scanned by means of embedded in a rigid pad switch (7) and from each scanning an electrical signal that measures the mass or thickness of the coil (5) on Location of each scan is generated.

14. The method of claim 13, wherein the electrical signals are combined together to form an output signal, preferably substantially added.

15. The method according to any one of claims 12-14, wherein the at least one electrical

Signal for controlling the speed of feeding the roll (5) and / or for obtaining quality characteristics of the roll (5) is used.