DE9320353U1 - Device for measuring the strength of a fiber structure with a tape guide for guiding the fiber tapes at the drafting system inlet - Google Patents

Description

TRÜTZSCHLER GMBH & CO. KG 21 852a

IN 4O5O MÖNCHENGLADBACH 3

Device for measuring the thickness of a fiber bundle with a tape guide for guiding the fiber tapes at the drafting system inlet

The invention relates to a device for measuring the thickness of a fiber bundle with a ribbon guide for guiding the fiber ribbons at the drafting system inlet, the walls of which are at least partially conical, bringing the incoming fiber ribbons together in one plane and which is followed by a pair of rollers, after which the fiber ribbons diverge again, in which a loaded, movable sensing element is present which, together with a stationary counter surface, forms a constriction for the continuous fiber bundle consisting of fiber ribbons and whose change in position, with different thicknesses of the fiber bundle, acts on a converter device for generating a control pulse.

In a known device, there is a device for guiding the ribbons at the drafting system inlet. The device comprises a conically tapered support plate for the fiber ribbons with sideways bent wall surfaces, which is followed by the ribbon guide with a rectangular entry cross-section, flat top and bottom surfaces and conically tapered side surfaces. The incoming fiber ribbons arranged next to each other slide over the support surface formed by the support plate and bottom wall of the ribbon guide. There is a gap between the incoming fiber ribbons and the side walls in the inlet area. The ribbon guide is located directly in front of a pair of take-off rollers, the parallel axes of which are aligned vertically. The pair of rollers also serves to measure a thickness of the fiber structure that lies within a predetermined tolerance range and is arranged so that the distance can be adjusted depending on the thickness of the fiber structure to be measured. The movable, spring-loaded roller as a loaded, movable sensing element can be moved horizontally in relation to the stationary roller. The stationary roller consists of three discs, the middle of which has a smaller diameter than the two outer ones, whereby the peripheral surface is designed as a groove

Intermediate gearing elements must be inserted, whereby, as explained above, in addition to a high level of construction effort, there is also the disadvantage of the cumulative tooth play between the individual gears, which leads to inaccuracies.

The invention is based on the object of creating a device of the type described above which avoids the disadvantages mentioned, which is in particular structurally simple and enables an improved measurement of the sliver at the drafting system inlet.

This problem is solved by the characterizing features of claim 1.

By means of the device according to the invention, the fiber bands are already compressed and scanned in the band guide, so that the rollers downstream of the band guide only pull off the fiber band that has already been scanned.

l§ These measures enable a separation of functions by ensuring that the

The scanning element upstream of the take-off rollers simultaneously compresses and scans the fiber bands in a simple manner. The downstream rollers can be designed to be much simpler in terms of construction and assembly because they are now only take-off rollers. In particular, the elimination of the measuring function avoids the considerable problems and effort involved in measuring that exist with the known device. In this way, the fiber bands are treated in stages with regard to the compression required for scanning and with regard to the compression required for take-off. According to the invention, a device is created that is significantly simplified in terms of construction and assembly and allows improved measurement of the fiber structure at the drafting system inlet.

Preferably, the movable sensing element of the tape guide is assigned in the area of the fiber tapes brought together next to one another in the narrow point and has a sliding surface which presses the fiber tapes next to one another against the stationary counter surface of the tape guide and the pair of rollers pulls off the scanned fiber tapes pressed together in the narrow point next to one another. Advantageously, the distance (a) between the movable sensing element and the clamping point of the pair of rollers is equal to or smaller than the staple length of the fiber material.

The distance (b) between the exit of the belt guide and the clamping point of the roller pair is preferably equal to or smaller than the staple length of the fiber material. The sensing element is preferably horizontal and at right angles to

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movable in the direction of tape travel. The sensing element is advantageously movable vertically and at right angles to the direction of tape travel. The tape guide expediently has at least one opening, with the sensing element reaching through the opening. The exit of the tape guide is preferably located directly in front of the nip of the take-off rollers. The narrow point is advantageously located directly in front of the exit of the tape guide. The take-off force is advantageously higher than the measuring force. The opening is preferably a recess. The recess is advantageously approximately rectangular. The sensing element is advantageously an approximately rectangular sensing element, the long edges of which run in the width direction and the short edges in the working direction. The outer end of the sensing element is preferably arranged at a short distance from the exit of the tape guide in the direction of the take-off rollers. The sensing element is advantageously mounted on a stationary pivot bearing. A lever of the pivot bearing expediently works together with a force element, e.g. counterweight, spring or the like. The sensing element is preferably mounted so that it can move in the horizontal direction. The sensing element is advantageously spring-mounted at one end. The sensing element is advantageously mounted on a holding element, e.g. a lever. The sensing element is preferably mounted so that it can rotate about a vertical axis. The sensing element advantageously has at least one inductive measuring element with a plunger core and plunger coil. The measuring element is advantageously an analogue, contactless distance sensor, e.g. an inductive proximity sensor. A stop is preferably assigned to the sensing element. The sensing element is advantageously loaded and supported by at least one force. The narrow point is advantageously designed in the manner of a photo diaphragm, i.e. as a diaphragm shutter with internal sliding surfaces. The movably mounted sensing element advantageously passes through a corresponding opening in the wall of the tape guide and loads the respective fiber structure with a sliding surface up to close to the cross-section of the substance. The narrow point preferably has two parallel surfaces between which a part of the movably mounted sensing element is fitted. Advantageously, the wall opposite the movably mounted sensing element runs at right angles to the parallel surfaces. The movably mounted sensing element is advantageously pre-tensioned by mechanical, electrical, hydraulic or pneumatic means, e.g. springs, weights, self-suspension, loading cylinders, magnets or the like, which can be adjustable. The movably mounted sensing element is preferably designed as an angle lever which is mounted approximately at the bending point in the recess of the tape guide, whereby either the angle lever or the tape guide is mounted in a fixed position and the angle lever is spring-loaded. Advantageously, the spring loading the angle lever rests with its free end on a finely adjustable abutment. Advantageously, the axes of the take-off rollers are arranged horizontally. Preferably, the axes of the

Take-off rollers are arranged vertically. Advantageously, another belt guide is arranged upstream of the belt guide, whereby the area between the two belt guides is connected to the outside air via at least one opening. The belt guide expediently has at least one ventilation opening. Preferably, the exit of the belt guide has a rectangular cross-section. Expediently, the

Exit of the belt guide into the nip between the take-off rollers.

The side walls of the wall guide are preferably designed to converge conically in the direction of the belt travel. The bottom wall and the top wall of the belt guide are advantageously designed to converge conically in the direction of the belt travel. The stationary wall element opposite the sensing element can be conveniently changed in position, e.g. using an adjusting screw. The sensing element is preferably designed to be trapezoidal. The sliding surface of the sensing element is advantageously convexly curved or rounded. The inner surface of the side wall of the belt guide and the sensing element are advantageously flush with one another.

Preferably, an average value is formed from the individual thickness of the fiber bands. The stationary counter surface is advantageously a sliding surface along which the fiber bands slide. The sliding surface of the sensing element is advantageously straight in the longitudinal direction. A pair of squeezing rollers is preferably installed upstream of the band guide. The first pair of stretching rollers is advantageously installed downstream of the band guide as take-off rollers. The delivery speed is advantageously approx. 150 m/min. The take-off force of the take-off rollers is preferably higher than the clamping force at the narrow point. The clamping force is advantageously smaller than the tear-off force. It is advantageous that at least the cover surface of the band guide can be opened and closed. The cover surface is preferably attached to a swivel joint. The pair of rollers is advantageously a cylindrical pair of calender rollers. It is useful in a device for measuring the thickness of a fiber structure with a tape guide for guiding the fiber tapes at the drafting system inlet, which has a top and bottom surface and whose side walls are conical, bringing the fiber tapes entering next to each other together in one plane, and which is followed by a pair of rollers, after which the fiber tapes diverge again next to each other, in which a loaded, movable sensing element is present, which forms a constriction for the continuous fiber structure consisting of fiber tapes with a stationary counter surface and whose change in position, when the fiber structure has a different thickness, acts on a converter device for generating a control pulse, the movable sensing element is assigned to the tape guide in the area of the fiber tapes brought together next to each other in the constriction and has a sliding surface which presses the fiber tapes next to each other against the stationary counter surface of the tape guide, compressing them, and the pair of rollers pulls the

The narrow point is pressed together and the scanned fiber bands lie next to each other. The edges of the band guide are preferably deburred. The band guide is advantageously a cast part. The contact surfaces of the band guide that are in contact with the fiber band expediently have a low coefficient of friction. The sliding surface of the sensing element that is in contact with the fiber band preferably has a low coefficient of friction. The band guide is advantageously enameled at least in the area of the contact surfaces. The sliding surface of the sensing element is advantageously enameled. The band guide is preferably made of a cast iron. The band guide is advantageously made of a ceramic. At least the sliding surface of the sensing element is advantageously made of a glass. At least the sliding surface of the sensing element is advantageously made of a ceramic. The ceramic is advantageously a sintered ceramic. The ceramic is advantageously an oxide ceramic. The band guide is preferably made of metal. The contact surfaces are advantageously polished. The contact surfaces are advantageously hardened. The contact surfaces preferably consist of hard material inserts. The guide advantageously has an essentially rectangular cross-section in the narrow point. The cross-section is advantageously tapered in the direction of the sensing element. Preferably, at least one of the walls delimiting the cross-section is inclined towards the opposite wall to reduce the cross-section. Advantageously, the tape guide has the shape of a truncated pyramid. Advantageously, the sensing element passes through a narrow side of the tape guide. A method for measuring the thickness of a fiber structure at the drafting system inlet is preferred, in which the individual fiber bundles are brought together and compressed, the density is detected by sensing means sliding on the fiber structure and converted into control pulses via converters. Advantageously, the fiber bundles are brought together and compressed in a plane next to one another. Advantageously, the control pulses are fed to a controller. Preferably, the controller adjusts the speed of at least its drive motor of the drafting section. Advantageously, the compression takes place in several stages. Advantageously, the fiber structure is vented before and/or during compression. Preferably, before or between the
In the individual compaction steps, the fibre structure is moved through pairs of rollers essentially without distortion.

The invention is explained in more detail below using exemplary embodiments shown in the drawings.

It shows:
Fig. 1a shows schematically a control section example

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the high-performance HS 900 line from Trützschler GmbH & Co. KG in side view,

Fig. 1b top view of the breeding area, Fig.2 as a top view in section the belt guide with
vertically arranged take-off rollers, Fig.3 the belt guide in section with horizontal
arranged take-off roller, Fig. 3a - 3e Sections through Fig. 3 along the lines aa
to ee, Fig.4 as a detail in the partial section the area of the Eng
steepness of the belt guide, Fig.5 in partial section two consecutively connected
Belt guides as top view, Fig. 6a as a side view, the position of the belt guide
to the first pair of rollers, Fig. 6b as front view the cross section of the band
guide, Fig.7 in perspective view the belt guide, Fig. 8a as front view the cross section of the band
guide with hinged lid, Fig. 8b the cover of the tape guide in the opened
Condition, Fig. 9a
Fig. 9b two tape guides put together,
a one-piece double tape guide,

Fig. 10a a composite double tape guide

with ventilation openings,

Fig. 10b a belt guide with ventilation opening,

Fig. 11a the tape guide in plan view,

Fig. 11b a section through the tape guide according to aa,

Fig. 12a the arrangement of an additional roller

pair in front of the belt guide in side view,

Fig. 12b the corresponding view as a plan view,

Fig. 13 two belt guides connected in series

with intermediate pair of squeezing rollers,

Fig. 14a the top view of a tape guide with

vertically arranged key element,

Fig. 14b shows the section through the tape guide according to.

Fig. 14a, section aa.

Fig. 1a shows a high-performance stretcher from Trützschier, for example the high-performance stretcher HS 900, schematically as a side view. The fiber ribbons 3, coming from cans (not shown), enter the ribbon guide 2 and are pulled by the take-off rollers 4, 5 and transported past the measuring element 6. The drafting system 1 essentially consists of the upper drafting system inlet roller 7 and the lower drafting system inlet roller 8, which are assigned to the pre-stretching area 9 with the pre-stretching upper roller 10 and the pre-stretching lower roller 11. The main stretching area 12 is located between the pre-stretching upper roller 10 with the pre-stretching lower roller 11 and the main stretching upper roller 13 and the main stretching lower roller 15. A second main stretching upper roller 14 is assigned to the main stretching lower roller 15. So it is a four over three stretching system.

The stretched fiber bands 3 reach the fleece guide 16 after passing the main stretching upper roller 14 and are pulled through the band funnel 17 by means of the delivery rollers 18, 18', combined into a single band and deposited in cans (not shown). The main stretching rollers 13, 14, 15 and the delivery rollers 18, 18' are guided by the

Main motor 19 is driven, which is controlled by computer 21. The signals determined by measuring element 6 on the sliver guide 2 are also received in computer 21 and are converted into commands that control the control motor 20, which drives the upper take-off roller 4, the lower take-off roller 5 and the rollers of the pre-stretching area 9, i.e. the drafting system inlet upper roller 7, the drafting system inlet lower roller 8, the pre-stretching upper roller 10 and the pre-stretching lower roller 11. In accordance with the values of the incoming fiber quantity from the fiber slivers 3 determined by measuring element 6, the fluctuations that occur are controlled by computer 21 using control motor 20 by changing the roller speeds on rollers 4, 5, 7, 8, 10, 11.

In Fig. 1b, the top view of the intake area, the upper take-off roller 4 is not shown for the sake of clarity. The fiber bands 3 are brought together in the band guide 2, the measuring element 6 is designed as a feeler element 22, which is mounted in a pivot bearing 30 and has two legs. One leg is in engagement with the fiber bands 3, the other leg, the lever 31, is acted upon by forces that will be explained later.

Fig. 2, the side view of the feed area in partial section, shows how the individual fiber strands 3 are brought together next to one another in the tape guide 2 and are scanned at the narrow point 23 of the tape guide 2 by means of the sensing element 22. The sensing element 22 is mounted in a pivot bearing 30, is acted upon by a tension spring 32 on the lever 31 and is also connected to a measuring element 48, which in the present case is designed as a moving coil instrument. Changes in the amount of fiber fed into the fiber tapes 3 are thereby recorded as a change in volume.

Deviating from Fig. 1b, the take-off rollers 4 and 5 are arranged vertically, i.e. that the fiber bands 3 run into the clamping point 26 of the rollers 4, 5 lying one above the other.

Fig. 3 is again shown as a top view in section without the upper take-off roller 4. Both rollers 4, 5 are arranged horizontally. The force P (not shown in detail) acts on the sensing element 22 in order to compress the parallel fiber strands 3 for measurement in the narrow point 23.

The sections through Fig. 3 are shown in Fig. 3a to 3e. As can be seen from Fig. 3c, eight fiber bands 3 run into the band guide 2, which

is limited by the side walls 40, 41, the ceiling 43 and the floor 42. Between the fiber bands 3, the side walls 40, 41 and the ceiling 43 there is still a lot of free space, i.e. air, which is caused by the conical tapering of the walls 40, 41, 42, 43,

as shown in Fig. 3b, is significantly reduced.
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Fig. 3a shows the section through the narrow part 23, i.e. the area where the bottom 42 and top 43 run parallel and the feeler element 22 with its sliding surface 34 presses the adjacent fiber bands 3 against the counter surface 41. The take-off rollers 4, 5 pull the compressed fiber bands 3 through the band guide outlet 27. The pressure between the rollers 4, 5 takes place at the clamping point 26, which is shown as section dd in Fig. 3d. The greatest compression of the fiber bands 3 is achieved at this point. They then fan out again into individual fiber bands 3, as shown in Fig. 3e, section ee.

Fig. 4 shows a special embodiment and as such also the one shown in Fig.

3a already shown narrow point 23. As in Fig. 3a, the top 43 and bottom 42 are designed as parallel surfaces 35. Likewise, the feeler element 22, which passes through the recess 28 in the narrow side of the tape guide 2 in the present case, i.e. the side 40, is mounted in the pivot bearing 30. Deviating from these identical embodiments, however, Fig. 4 shows that the counter surface 41, i.e. the wall of the tape guide opposite the feeler element 22, is designed to be adjustable in the area of the narrow point 23. The adjustment can be made using the adjusting screw 38.

Fig. 5 shows the series connection of two band guides 2, 2 ¹ . The fiber bands 3 first enter the upstream band guide 2' and are pre-compressed here. The band guide 2 is arranged at a short distance from the band guide 2' so that air can escape at this distance. This practically forms a ventilation opening 37. In the band guide 2, the fiber bands 3 are further compressed, which then lie closely against the inner wall of the band guide 2, i.e. against the contact surfaces 44. To reduce friction, these contact surfaces 44 are therefore polished, enameled or provided with smooth hard material inserts, which reduce friction.

The probe element 22 is located in a recess 28 and is held in its position by the pivot bearing 30. It is equipped with a lever 31, which is acted upon by a spring 32 arranged in an abutment 36. Furthermore, the measuring element 48, which is designed as a moving coil instrument, engages the lever 31.

Fig. 6a shows the feed area in side view. In this design, the tape guide outlet 27 is largely advanced into the roller gap 29 between the upper take-off roller 4 and the lower take-off roller 5 in order to achieve the smallest possible distance between the tape guide outlet 27 and the clamping point 26. In the front area of the tape guide 2, near the tape guide inlet 45, a ventilation opening 37 is arranged.

Fig. 6b shows the front view of the belt guide 2, i.e. the cross section. As can be seen from this, the belt guide 2 is designed as a truncated cylinder with rounded edges, with the boundaries being formed by the counter wall 41, the side wall 40, the base 42 and the cover 43. These inner trapezoidal surfaces are the contact surfaces 44. The base surface 42 and the cover surface 43 are the same size and have an extension C that is significantly larger than the corresponding extension D of the counter surface 41 or wall surface 40.

In Fig. 7, the tape guide 2 is shown in perspective. The area of the tape guide outlet 27 is bevelled in order to get as close as possible to the clamping point 26.

Fig. 8a corresponds essentially to Fig. 6b. However, in this construction the cover 43 is designed to be foldable, i.e. it is mounted in a swivel joint 39, so that it can be folded open to clean the belt guide 2, as shown in Fig. 8b.

Fig. 9a and 9b show two-stage forms of the tape guide 2, whereby according to Fig. 9a a tape guide ²¹ is connected to the tape guide 2 via connectors 25. This makes it possible to detach the tape guide 2' from the tape guide 2 and to remove any fiber residues - snow - or impurities that may have accumulated in the area of the ventilation opening 37. In this construction too, the fiber tapes 3 enter the tape guide 2' via the tape guide inlet 45', leave it via the tape guide outlet 27', pass through the tape guide inlet 45 and leave the tape guide 2 via the tape guide outlet 27.

The structure of the construction according to Fig. 9b is analogous. However, in this case the tape guide 2' and the tape guide 2 form an integral part. The air outlet openings 37 are arranged on the side and in the cover surface 43 of the fiber tape guide 2', as in Fig. 9a.

Fig. 10a and 10b are further embodiments, whereby the construction according to Fig. 10a is again designed in two stages and in the area of the tape guide outlet 27', i.e. at the end of the tape guide 2',

Ventilation openings 37 are present.
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According to Fig. 10b, the belt guide 2 is designed to be longer, with the side walls being less inclined towards each other. Ventilation openings 37 are provided in both the bottom surface 42 and the top surface 43.
In the inlet area, the belt guide 2 is provided with flanges 49 which have holes 50 for fastening to the machine frame.

Fig. 11a and 11b differ from Fig. 9 and 10 in that the side walls are not curved but straight.

Fig. 11b is the section through Fig. 11a along the line aa. Here too, the narrow section 23 in which the measurement takes place has parallel walls 35. The sensing element 22 presses with its sliding surface 34 onto the fiber strands 3 (not shown) so that they are pressed against the counter surface 41.

According to Fig. 12a and 12b, a pair of squeeze rollers 46, 47 is arranged upstream of the band guide 2, which has the task of pulling the fiber bands 3 out of the supplied drums and thereby relieving the load on the take-off rollers 4, 5. There is thus practically no more distortion between the two pairs of rollers. The take-off rollers 4, 5 only have to overcome the frictional resistance caused by the compression of the fiber bands 3 between the fiber bands and the band guide 2 with the sensing element 22 arranged therein, which act on the fiber bands 3.
The force exerted can therefore be lower, so that tearing of one or more fiber bands 3 is avoided.

Fig. 13 shows a similar design variant to Fig. 12, but in this case there are two strip guides 2, ²¹ , between which the pair of squeeze rollers 46, 47 is inserted. The position of the take-off rollers 4, 5, which in this case are arranged vertically, has also been changed.

Fig. 14a, 14b show an alternative arrangement of the sensing element 22. In the constructions described so far, the sensing element 22 penetrated a narrow side of the band guide 2 and compressed the fiber bands 3 so that the expansion in the transverse region, i.e. region C according to Fig. 11b, was reduced.

According to the present alternative, the dimension D is now reduced, i.e. the fiber bands 3 are compressed across the width, in this case from above. The sensing element is designed in such a way that in addition to the scanning movement, i.e. the compression movement in the direction of the fiber bands 3, it can also carry out a pivoting movement and thus takes into account that fiber bands 3 of different thicknesses may be arranged next to one another.

List of terms: Drafting system 1 Belt guide 2 Sliver 3 upper take-off roller 4 lower take-off roller 5 Measuring element 6 Drafting system infeed, top roller 7 Drafting system inlet, bottom roller 8th Pre-stretching area 9 Pre-stretching top roller 10 Pre-stretching bottom roller 11 Main stretching area 12 first main stretching top roller 13 second main stretching top roller 14 Main stretching bottom roller 15 Fleece guide 16 Belt funnel 17 Delivery roller 18 Delivery roller 18' main engine 19 Control motor 20 calculator 21 Key element 22 bottleneck 23 Converter 24 Interconnects 25 Clamping point 26 Tape guide output (of 2) 27 Tape guide output (from 2') 27' Recess 28 Roll gap 29 Pivot bearing 30 lever 31 Feather 32 attack 33 Sliding surface 34

35 Parallel surface 36 Abutment 37 Vent opening 38 Adjustment screw 39 Swivel joint 40 Side wall 41 Counter surface 42 Floor 43 Ceiling 44 Contact surface 45 Tape guide input 46 upper squeezing roller 47 lower squeeze roller 48 Measuring element 49 flange 50 drilling

Claims (1)

TRÜTZSCHLER GMBH & CO. KG ^{21 852 a} IN 4&Ogr;5&Ogr; MÖNCHENGLADBACH 3 Protection claims 1) Device for measuring the thickness of a fiber structure with a band guide for guiding the fiber bands at the drafting system inlet, the walls of which are at least partially conical, bringing the incoming fiber bands together in one plane and which is followed by a pair of rollers, after which the fiber bands diverge again, in which a loaded, movable sensing element is present which, with a stationary counter surface, forms a bottleneck for the passing fiber structure consisting of fiber bands and whose change in position, with different thicknesses of the fiber structure, acts on a converter device for generating a control pulse, characterized in that the sensing element (22) is assigned to the band guide (2), the fiber bands (3) are compressed and scanned in the band guide (2) in one plane and the pair of rollers (4, 5) pulls off the scanned fiber bands (3). 2) Device according to claim 1, characterized in that the movable sensing element (22) is assigned to the band guide (2) in the area of the fiber bands (3) brought together next to one another in the narrow point (23) and has a sliding surface (34) which presses the fiber bands (3) next to one another in a compacting manner against the stationary counter surface (41) of the band guide (2) and the pair of rollers (4, 5) the scanned fiber ribbons (3) compressed in the constriction (23) are pulled off next to one another. 3) Device according to claim 1 or 2, characterized in that the distance (a) between the movable probe element (22) and the clamping point (26) of the roller pair (4, 5) is equal to or smaller than the staple length of the fiber material. 4) Device according to one of claims 1 to 3, characterized in that the distance (b) between the outlet (27) of the belt guide (2) and the clamping point (26) of the roller pair (4, 5) is equal to or smaller than the staple length of the fiber material. —14— · ··· 5) Device according to one of claims 1 to 4, characterized in that the sensing element (22) is movable horizontally and at right angles with respect to the tape running direction. 6) Device according to one of claims 1 to 5, characterized in that the sensing element (22) is movable vertically and at right angles with respect to the tape running direction. 7) Device according to one of claims 1 to 6, characterized in that the tape guide (2) has at least one opening (28), wherein the sensing element (22) passes through the opening (28). 8) Device according to one of claims 1 to 7, characterized in that the outlet (27) of the belt guide (2) is located immediately in front of the roller gap (29) of the take-off rollers (4, 5). 9) Device according to one of claims 1 to 8, characterized in that the constriction (23) is arranged immediately in front of the outlet (27) of the belt guide (2). 10) Device according to one of claims 1 to 9, characterized in that the withdrawal force is higher than the measuring force. 11) Device according to one of claims 1 to 10, characterized in that the opening (28) is a recess (28'). 12) Device according to one of claims 1 to 7, characterized in that the recess (28 ¹ ) is approximately rectangular. 13) Device according to one of claims 1 to 12, characterized in that the sensing element (22) is an approximately rectangular sensing element, the long edges of which run in the width direction and the short edges of which run in the working direction. 14) Device according to one of claims 1 to 13, characterized in that the outer end of the probe element (22) is at a short distance from the output (27) of the tape guide (2) is arranged in the direction of the take-off rollers (4, 5). 15) Device according to one of claims 1 to 14, characterized in that the sensing element (22) is mounted on a stationary rotary bearing (30). -15-! 16) Device according to one of claims 1 to 15, characterized in that a lever (31) of the rotary bearing (30) interacts with a force element, e.g. counterweight, spring or the like. 17) Device according to one of claims 1 to 16, characterized in that the sensing element (22) is mounted so as to be movable in the horizontal direction. 18) Device according to one of claims 1 to 17, characterized in that the touch element (22) is spring-mounted at one end. 19) Device according to one of claims 1 to 18, characterized in that the button element (22) is mounted on a holding member, e.g. a lever. 20) Device according to one of claims 1 to 19, characterized in that the sensing element (22) is mounted so as to be rotatable about a vertical axis. 21) Device according to one of claims 1 to 20, characterized in that the sensing element (22) has at least one inductive measuring element (48) with plunger core and plunger coil. 22) Device according to one of claims 1 to 21, characterized in that the measuring element is an analogue contactless distance sensor, e.g. an inductive proximity switch. 23) Device according to one of claims 1 to 22, characterized in that a stop (33) is associated with the probe element (22). 24) Device according to one of claims 1 to 23, characterized in that the probe element (22) is loaded and supported by at least one force. 25) Device according to one of claims 1 to 24, characterized in that that the constriction (23) is designed in the manner of a photo diaphragm, i.e. as a diaphragm shutter with internal sliding surfaces. 26) Device according to one of claims 1 to 25, characterized in that the movably mounted sensing element (22) passes through a corresponding opening in the wall of the band guide (2) and loads the respective fiber structure with a sliding surface (34) up to close to the substance cross-section. -16-: 27) Device according to one of claims 1 to 26, characterized in that the constriction (23) has two mutually parallel surfaces (35) between which a part of the movably mounted probe element (22) is fitted. 28) Device according to one of claims 1 to 27, characterized in that the wall (41) opposite the movably mounted probe element (22) runs at right angles to the parallel surfaces (35). 29) Device according to one of claims 1 to 28, characterized in that the pre-tensioning of the movably mounted probe element (22) is carried out by mechanical, electrical, hydraulic or pneumatic means, e.g. springs, weights, self-suspension, loading cylinders, magnets or the like, and can be adjustable. 30) Device according to one of claims 1 to 29, characterized in that the movably mounted touch element (22) is designed as an angle lever which is mounted approximately at the bending point in the recess (28) of the tape guide (2), whereby either the angle lever or the tape guide (2) is mounted in a fixed position and the angle lever is spring-loaded. 31) Device according to one of claims 1 to 30, characterized in that the spring 32 which loads the angle lever (31) rests with its free end on a finely adjustable abutment (36). 32) Device according to one of claims 1 to 31, characterized in that the axes of the extraction rollers (4, 5) are arranged horizontally. 33) Device according to one of claims 1 to 32, characterized in that the axes of the take-off rollers (4, 5) are arranged vertically. 34) Device according to one of claims 1 to 33, characterized in that a further belt guide (2 ¹ ) is arranged upstream of the belt guide (2), the area between the two belt guides (2, 2') being connected to the outside air via at least one opening (37). 35) Device according to one of claims 1 to 34, characterized in that the belt guide (2) has at least one ventilation opening (37). 36) Device according to one of claims 1 to 35, characterized in that the inlet (45) of the belt guide (2) has a rectangular cross-section. 37) Device according to one of claims 1 to 36, characterized in that the outlet (27) of the tape guide (2) has a rectangular cross-section. 38) Device according to one of claims 1 to 37, characterized in that the outlet (27) of the belt guide (2) extends into the roller gap (29) between the take-off rollers (4, 5). 39) Device according to one of claims 1 to 38, characterized in that the side walls (40, 41, 42, 43) of the belt guide (2) are designed to converge conically in the belt travel direction. 40) Device according to one of claims 1 to 39, characterized in that the bottom wall (42) and the top wall (43) of the belt guide (2) are designed to converge conically in the direction of belt travel. 41) Device according to one of claims 1 to 40, characterized in that the fixed wall element (41) opposite the probe element (22) can be changed in position, ζ. β. by means of an adjusting screw (38). 42) Device according to one of claims 1 to 41, characterized in that the probe element (22) is trapezoidal. 43) Device according to one of claims 1 to 42, characterized in that the sliding surface (34) of the probe element (22) is convexly curved or rounded. 44) Device according to one of claims 1 to 43, characterized in that the inner surface of the side wall of the tape guide (2) and the sensing element (22) merge flush into one another. 45) Device according to one of claims 1 to 44, characterized in that an average value is formed from the individual thickness of the fiber bands (3). -18-: 46) Device according to one of claims 1 to 45, characterized in that the stationary counter surface (41) is a sliding surface along which the fiber bands (3) slide. 47) Device according to one of claims 1 to 46, characterized in that the sliding surface (34) of the probe element (22) is straight in the longitudinal direction. 48) Device according to one of claims 1 to 47, characterized in that a pair of squeezing rollers (46, 47) is arranged upstream of the belt guide (2). 49) Device according to one of claims 1 to 48, characterized in that the first pair of stretching rollers (10, 11) is arranged downstream of the strip guide (2) as take-off rollers. 50) Device according to one of claims 1 to 49, characterized in that the delivery speed is approximately 150 m/min. 51) Device according to one of claims 1 to 50, characterized in that the withdrawal force is higher than the clamping force at the constriction (23). 52) Device according to one of claims 1 to 51, characterized in that the clamping force is smaller than the tear-off force. 53) Device according to one of claims 1 to 52, characterized in that at least the cover surface (43) of the belt guide (2) can be folded open and closed. 54) Device according to one of claims 1 to 53, characterized in that the cover surface (43) is attached to a swivel joint (39). 55) Device according to one of claims 1 to 54, characterized in that the pair of rollers (4, 5) is a cylindrical calender roller pair. 56) Device according to one of claims 1 to 55 for measuring the thickness of a fiber structure with a tape guide for guiding the fiber tapes at the drafting system inlet, which has a top and bottom surface and whose side walls are conical, the fiber tapes entering next to each other are designed to join together laterally next to each other in a plane and which is followed by a pair of rollers after which the fiber tapes are again placed next to each other · diverge, in which a loaded, movable sensing element is present which, together with a stationary counter surface, forms a constriction for the continuous fiber structure consisting of fiber bands and whose change in position, when the thickness of the fiber structure differs, acts on a converter device for generating a "control pulse, characterized in that the movable sensing element (22) of the band guide (2) is assigned in the area of the fiber bands (3) brought together next to one another in the constriction (23) and has a sliding surface (34) which presses the fiber bands (3) next to one another against the stationary counter surface (41) of the band guide (2) in a compressing manner and the pair of rollers (4, 5) pulls off the scanned fiber bands (3) pressed together in the constriction (2, 3) next to one another. 57) Device according to one of claims 1 to 56, characterized in that the edges of the tape guide (2) are deburred. 58) Device according to one of claims 1 to 57, characterized in that the band guide (2) is a cast part. 59) Device according to one of claims 1 to 58, characterized in that the contact surfaces (44) of the band guide (2) in contact with the fiber band (3) have a low coefficient of friction. 60) Device according to one of claims 1 to 59, characterized in that the sliding surface (34) of the sensing element (6) in contact with the fiber band (3) has a low coefficient of friction. 61) Device according to one of claims 1 to 60, characterized in that the band guide (2) is enamelled at least in the region of the contact surfaces (44). 62) Device according to one of claims 1 to 61, characterized in that the sliding surface (34) of the touch element (6) is enamelled. 63) Device according to one of claims 1 to 62, characterized in that that the tape guide (2) consists of glass. 64) Device according to one of claims 1 to 61, characterized in that the tape guide (2) consists of a ceramic. 65) Device according to one of claims 1 to 64, characterized in that at least the sliding surface (34) of the touch element (6) consists of a glass. 66) Device according to one of claims 1 to 65, characterized in that at least the sliding surface (34) of the touch element (6) consists of a ceramic. 67) Device according to one of claims 1 to 66, characterized in that the ceramic is a sintered ceramic. 68) Device according to one of claims 1 to 67, characterized in that the ceramic is an oxide ceramic. 69) Device according to one of claims 1 to 62, characterized in that the band guide (2) consists of a metal or a metal alloy. 70) Device according to one of claims 1 to 69, characterized in that the contact surfaces (44) are polished. 71) Device according to one of claims 1 to 70, characterized in that the contact surfaces (44) are hardened. 72) Device according to one of claims 1 to 71, characterized in that the contact surfaces (44) consist of hard material inserts. 73) Device according to one of claims 1 to 72, characterized in that the tape guide (2) in the narrow point (23) has a substantially rectangular cross-section. 74) Device according to one of claims 1 to 73, characterized in that the cross section tapers in the direction of the probe element (6). 75) Device according to one of claims 1 to 74, characterized in that at least one of the walls (40, 41, 42, 43) delimiting the cross section is inclined towards the opposite wall for the purpose of tapering the cross section. 76) Device according to one of claims 1 to 75, characterized in that the tape guide (2) has essentially the shape of a truncated pyramid. -21- TRÜTZSCHLER GMBH & CO. KG 21 852a IN D-41199 MÖNCHENGLADBACH 77) Device according to one of claims 1 to 76, characterized in that the sensing element (6) passes through a narrow side (40, 41) of the tape guide (2). 78) Device for measuring the thickness of a fiber structure at the drafting system inlet, characterized in that the individual fiber bands are brought together and compressed, the density is detected by scanning means sliding on the fiber structure and is converted into control pulses via converters. 79) Device according to claim 78, characterized in that the fiber bands can be brought together and compressed in a plane lying next to one another. 80) Device according to one of claims 78 and 79, characterized in that control pulses can be fed to a controller. 81) Device according to one of claims 78 to 80, characterized in that the controller is able to adjust the speed of at least one drive motor of the drafting section. 82) Device according to one of claims 78 to 81, characterized in that the compression takes place in several stages. 83) Device according to one of claims 78 to 82, characterized in that the fiber structure can be ventilated before and/or during compaction. 84) Device according to one of claims 78 to 83, characterized in that before the individual compaction steps, the fiber structure can be moved essentially without distortion by pairs of rollers.