EP0271115A2 - Method and apparatus for automatically levelling sliver density variations in textile machines such as carding or drawing machines, and the like - Google Patents

Abstract

In a method or a device for automatically compensating for band density fluctuations in textile machines, e.g. Cards, draw frames and the like, the density of a fiber mat (15) or a fiber sliver (15.1) fed into a feed medium, as well as the density of a fiber sliver (8) at the output of the textile machine and the resulting signals of a controller are measured at the entrance of the textile machine Entered (17), which produces an output signal (22) to regulate the speed of a feed roller (9) belonging to the feed means in accordance with the two density signals. By fixing the position of a feed plate (10) opposite the feed roller for operation, different forces arise in the nip area (23), in which the fiber mat is increasingly compressed, depending on the density of the fiber mat (15), which are detected with the aid of different measuring means which generate the above-mentioned signal (16) given to the controller (17).

Description

The invention relates to a method and a device for automatically compensating strip density fluctuations in textile machines, such as cards, draw frames and the like, as defined in the preamble of the first method and the first device claim.

The homogenization of the fiber wadding - also called the fiber mat - at the entrance to a textile machine that processes the wadding is an essential prerequisite for the uniformity of the fiber sliver emitted by this machine. With increasing processing speed, this prerequisite becomes even more important, since fewer machines are used for the same amount of fiber wadding to be processed, so that the possibility of duplication from a larger number of machines and the resultant equalization of the product becomes smaller.

There is therefore considerable prior art in order to achieve this object, of which the following patent specifications are cited as examples.

From US-A-4275483 a feed means of a card is known, consisting of a fixedly arranged feed plate and a drivable feed roller movably arranged above it. This feed roller is pressed at both ends by means of springs against the fiber wadding located between the feed roller and the trough plate. A similar arrangement is known from DE-A-32 05 776.

The movements of the feed roller resulting from the unevenness in the fiber wool are emitted by sensors provided at both ends of the feed roller as signals to a control unit, which calculates the necessary speed change of the feed roller in order to compensate for these unevenness as far as possible.

The main disadvantage of this system is that the feed roller to be driven is also used to scan the unevenness in the fiber wadding, which inevitably leads to interference in the measurement signals, even if precautions are taken in the arrangement of the drive of the feed roller to the directions of the To obtain driving force of the feed roller drive perpendicular to the direction of movement of this roller during the scanning.

This disadvantage is eliminated by the device of FR-A 23 22 943. This suggests a stationary feed roller and scans the unevenness of the cotton to be fed in using a continuous or a trough plate divided into pedals. The trough plate, respectively. the pedals are pivoted so that they can move against or away from the feed roller, thereby removing the bumps units of the fiber wadding.

A disadvantage of this system is not the measuring principle, but the type of fiber transfer to a subsequent licker-in roller (also called a beater), in that the fiber transfer point on the trough plate (or pedals) moves due to the swiveling of the trough plate relative to the stationary licker-in roller, which means that the position of the transfer point of the fiber wadding from the trough plate (or pedals) to the licker-in roller also moves alternately in the direction of rotation of the licker-in roller and against it, which creates an unrest in the transfer of the fibers to the licker-in roller.

Another example to remedy the disadvantages mentioned first is shown in DE-A-29 12 576, in that a sensor element provided near or adjacent to the fixed trough plate detects the density of the fiber floss lying on the trough plate and signals it outputs a control device to adjust the speed of the feed roller.

The disadvantage of this system is that the density of the fiber wadding is measured before it is drawn in between the trough plate and the feed cylinder, so that changes in the fiber wadding can occur until it is drawn in between the trough plate and the feed cylinder, which then no longer match the measured values would match.

Basically, it should be mentioned that a trough plate and a feed plate as well as a feed cylinder and a feed roller are each the same el acts.

As already mentioned, the aforementioned examples relate to essential, but not all, prerequisites for the uniformity of the sliver delivered by this machine.

Another essential prerequisite for the automatic balancing of the sliver, particularly in the case of a card or card, is that the sliver emitted by it is checked in order to determine losses between the feeding of the fiber mat and the gathering of the nonwoven fabric at the exit of the card.

DE-A-29 12 576, already mentioned, shows and describes the combination of the aforementioned equalization of the fed-in fiber wadding with the control of the sliver at the exit of the card or of the drafting system. However, this combination also has the disadvantages already described for the publication.

The invention is therefore based on the object of finding a system which detects and corrects the inequalities in the sliver simply and yet sufficiently precisely without accepting the disadvantages mentioned.

This object is achieved with the inventions defined in the characteristic of the first method and in the characteristic of the first device claim.

It is advantageous in the method according to the invention or in the device according to the invention that the measuring point or the measuring plane, respectively. the measuring direction, can be provided such that the determination of the change in thickness of the fiber mat can be carried out close to the narrowest nip between the feed plate and the feed roller, i.e. essentially close to the point at which the fiber mat is taken over by the licker-in roller. This creates a very small distance between the measuring point and the fiber transfer point, i.e. the time of the measurement is very close to the time of the necessary speed correction.

• Fig. 1 eine Längsansicht einer Karde mit einem er­findungsgemässen Faserbandausgleich, schematisch dargestellt,
• Fig. 2 der erfindungsgemässe Faserbandausgleich von Fig. 1, vergrössert dargestellt,
• Fig. 3 eine Variante des Faserbandausgleiches von Fig. 2,
• Fig. 4 Teile des Faserbandausgleiches von Fig. 1, vergrössert dargestellt,
• Fig. 5 ein Grundriss eines Teiles von Fig. 4,
• Fig. 6 bis 29 je Varianten der Faser-Einspeisemittel, in einer Darstellung mit Längsansicht und Grund­riss analog Fig. 4 und 5,
• Fig. 30 ein Streckwerk mit dem erfindungsgemässen Faserbandausgleich, schematisch dargestellt,
• Fig. 31 das Teil von Fig. 4 mit weiteren Detailanga­ben, schematisch dargestellt,
• Fig. 32 ein Teil der Vorrichtung von Fig. 4, vergrös­sert und im Schnitt gemäss den Linien I von Fig. 33 dargestellt,
• Fig. 33 ein Teil der Vorrichtung von Fig. 4, vergrös­sert und in Blickrichtung II (Fig. 31) darge­stellt.

In the following, the invention is explained in more detail with the aid of drawings which only show execution routes. It shows:

• 1 shows a longitudinal view of a card with a sliver compensation according to the invention, shown schematically,
• 2 the fiber sliver compensation according to the invention from FIG. 1, shown enlarged,
• 3 shows a variant of the sliver compensation of FIG. 2,
• 4 parts of the sliver compensation of FIG. 1, shown enlarged,
• 5 is a plan view of part of FIG. 4,
• 6 to 29 each variant of the fiber feed means, in a representation with a longitudinal view and a plan similar to FIGS. 4 and 5,
• 30 shows a drafting system with the sliver compensation according to the invention, shown schematically,
• 31 the part of FIG. 4 with further details, shown schematically,
• 32 shows part of the device from FIG. 4, enlarged and shown in section along lines I of FIG. 33,
• 33 shows part of the device from FIG. 4, enlarged and shown in viewing direction II (FIG. 31).

A card 1 comprises from left to right, as seen in FIG. 1, at the card entry a fiber feed means 2, a licker-in roller 3, also called a beater, a reel 4 with a cover 5, a fiber pile removal roller 6, also called a doffer roller, one Fiber pile compression unit 7 for forming a card sliver 8.

The fiber feed means 2 comprises a rotatable and drivable feed roller 9, also called feed cylinder, a feed plate 10, also called trough plate, which cooperates with the feed roller and is pivotally mounted about a pivot axis 11.

The feed roller 9 is arranged stationary, and the pivotability of the feed plate 10 is limited by an adjusting screw 12, in the direction of movement away from the feed roller 9, and by a stop mentioned later in the opposite direction.

The feed roller 9 is driven by a gear motor 13.

In operation, a fiber mat 15 is fed to the fiber feed means 2 on a feed plate 14. By rotating the feed roller 9 in the circumferential direction U, the fiber mat is fed in a manner known per se to the much faster rotating licker-in roller than the compressed fiber mat.

The nonwoven fabric processed between the drum 4 and the lid 5 is removed from the doffer roller 6 and passed on to the nonwoven compression unit 7, in which the nonwoven fabric is compressed into the card sliver 8.

Immediately after this compression unit 7, viewed in the conveying direction of the sliver, a device 110 known from EP-A-0 078 393 determines the mass or density of the sliver and outputs a signal 111 corresponding to the density to a controller 17.

The ratio of the peripheral speed of the doffer roller 6 to the peripheral speed of the feed roller 9 gives the so-called draft ratio of the card.

Furthermore, by inserting the fiber mat 15, the food plate 10 is pivoted away from the feed roller 9 until the food plate contacts the set screw 12. This position of the food plate 10 is referred to as the operating position.

With the aid of this adjusting screw 12, the degree of compression of the fiber mat 15 located between the feed plate 12 and feed roller 9 is accordingly determined. This clamping effect causes measurable variables described later in the fiber feed means 2, by means of which a signal 16 corresponding to the density of the “pinched” fiber mat 15 is continuously obtained.

To obtain the signal 16, two signals 16A, 16B from left to right on the pivot axis 11 of the feed plate 10, which sense the transverse force of the bearing journal of the feed trough, can be used, as will be described later with reference to FIG. 5. These signals 16A, 16B are applied to a measuring amplifier 16C, which first adds the signals and then amplifies them, so that the signal 16 is produced, which represents an amplified mean signal. The measuring amplifier 16C converts the signals from the strain gauge transducers into a DC voltage which is between -10 and +10 V.

The signal 16 is input to a controller 17 together with a manipulated variable signal 18, a rotational speed signal 19 of the doffer roller 6 and a rotational speed signal 20 of the geared motor shaft 21, as well as the signal 111 already mentioned, the manipulated variable signal 18 and the speed signal 19 of the doffer roller 6 have a predetermined value. The value of the signal box signal 18 can be selected at a decade switch 18A and finally determines the desired band number.

The controller "processes" the aforementioned signals into an output signal 22, by means of which the speed of the geared motor 13 is corrected in accordance with the deviations in the density of the fiber mat 15 in a clamping gap area 23 and the deviations determined by the device 110, that the density of the sliver 8 when leaving the card 1 is substantially balanced.

The controller 17 essentially consists of a microcomputer 17a from Texas Instr. Type 990 / 100MA with the necessary number of EPROM's type TMS 2716, also from Texas Instr., For programming the control functions, as well as a control unit 17b type D 10 AKN RV419D-R from AREG (Federal Republic of Germany, Gemrigheim). The control unit 17B amplifies a speed signal emitted by the microcomputer to the output signal 22 and receives the signal 20 for checking and regulating the feed roller speed.

The run-in signal 16 is first processed in a stage 17C. At regular, short successive intervals, the mean value of the incoming signal is recalculated from a fixed number of the last read values. In this way, the long-term deviation of the fiber template can be eliminated. The averaging process that is carried out again and again has an effect as if there was a drift filter. In a very short time interval of approximately 100 ms, the instantaneous value of the incoming signal is compared with the last determined mean value in stage 17C in such a way that the quotient mean value / instantaneous value is formed in order to obtain a signal y which shows whether the fiber density in the nip is currently increasing or decreasing. The signal y can be understood as a "trend signal". In the subsequent stage 17D, which is designed as a multiplier, the signal y is multiplied by a control signal x from the microcomputer 17A and the result of this multiplication, possibly taking into account a further constant, is supplied to the AREG controller 17B as a setpoint. This is shown schematically by means of the corresponding arrow between the blocks 17D and 17B.

The AREG controller represents independent control electronics connected upstream of the control motor 13. The setpoint value determined by the stage 17D is compared in the control electronics with the tachometer actual value 20, the difference is amplified and fed to the motor via the power circuits. The control electronics 17B works as a voltage metering and only supplies the motor with as much voltage 22 as is required to apply the required torque and maintain the speed.

K = Proportional-Anteil
T_x= Integral-AnteilAs mentioned earlier, the value of the control value signal 18, which is selected at the decade switch 18, represents the desired band number. This setpoint signal 18 is fed together with the actual value signal for the band number or band density to the stage 17E, which subtracts the two signals to determine the deviation. This deviation, that is, the deviation Proportional signal e is supplied to the microcomputer 17A, which in this example is formed by corresponding EPROMS and PI controllers. In this controller, the previously mentioned control value x is calculated according to the following formula:

K = proportional part
T _x = integral part

In addition, it should be noted that the tachometer initiator 19A measures the speed of the pickup 6. This speed, which should be constant during operation and is regulated to a constant value during operation, is an important value for the microcomputer 17A, especially when the arrangement is started up, since the value is not constant here and a corresponding start-up control must be carried out .

It will be appreciated that the functions of stages 17C and 17B and 17E can be performed in the microcomputer as needed, if programmed accordingly.

The present description shows how the entire arrangement is regulated, starting from the absolute value of the strip measured on the step roller block.

How the individual signals 16A, 16B are generated as a function of the fiber density in the clamping gap is now explained below.

The nip area 23 is defined by the interaction of the feed roller 9 and the feed plate 10 by the fiber mat 15 in this area of the original thickness D is compressed to a thickness (not shown), which has this immediately before leaving the area 23. The clamping gap region 23 thus ends at the edge of the food plate 10, referred to as the fiber delivery edge 24, at which the fiber mat 15 is no longer clamped by the food plate 10.

The directions of rotation of the feed roller 9, the breeze 3, the reel 4 and the doffer roller 6 are each identified by the arrows U. The fiber material moves through the card in accordance with these directions of rotation.

With the aid of the speed variations of the feed roller (9) caused by the regulation, inequalities in the density of the fiber mat (15) in the nip area (23) are compensated for when the fiber mat passes from the feed plate (10) to a lickerin roller (3).

FIG. 2 shows the fiber feed means 2 from FIG. 1 in an enlarged representation and in somewhat more detail, for which reason the same elements are provided with the same reference symbols.

It can be seen from this figure that the pivot axis 11 is accommodated in a stationary bearing housing 26 belonging to the machine housing 25 (only indicated with hatching).

Also attached to the machine housing 25 is a stop 27 which prevents the feed plate 10 from resting on the feed roller 9 when there is no fiber mat 15.

Likewise, a carrier 28 receiving the set screw 12 and the gear motor 13 are fastened to the machine housing 25.

FIG. 3 shows a variant 2.1 of the fiber feed means from FIGS. 1 and 2, so that the same elements are provided with the same reference symbols.

This variant has a feed plate 29 arranged below the feed roller 9, as seen in FIG. 3, which is pivotably mounted by means of a pivot axis 31 accommodated in a bearing housing 30 fastened to the machine housing 25.

A set screw 32 limits the pivoting movements of the feed plate 29 in a direction away from the feed roller 9, while a stop 33 prevents the feed plate 29 from coming into contact with this roller in one direction of movement against the feed roller 9, the latter direction of movement of the feed plate 29 is caused by a compression spring 34.

The set screw 32 is received by means of a carrier 35 and the spring 34 by means of a carrier 36 each from the machine housing 25.

The stop 33 is the end face of a feed plate 37, which is also attached to the machine housing 25.

The clamping gap area 23.1 corresponds to the clamping gap area 23 of FIGS. 1 and 2.

In the following, with the help of the other figures, measuring means are defined which are used to generate the signal 16 emitted by the feed means 2.

4, 8, 12, 16, 20 and 24 show elements of the feed means of FIG. 2, while FIGS. 6, 10, 14, 18 and 22 have elements of the feed means of FIG. 3. Accordingly, the same elements are provided with the same reference numerals in the figures mentioned.

5 shows the feed plate 10, the pivot axis 11 and the bearing housing 26 as well as a second bearing housing 26.1 which also receives the pivot axis 11.

The feed plate 10 has two bearing legs 38, by means of which the feed plate 10 is pivotably mounted on the pivot axis 11.

In the spaces between the bearing legs 38 and the bearing housings 26, respectively. 26.1, the pivot axis 11 each has a surface 39 (FIGS. 32 and 33) for receiving one strain gauge 90 each. These strain gauges are arranged in such a way that they each generate a signal corresponding to the magnitude of a force F (FIGS. 4, 31 to 33) generated during operation on the feed plate 10, both signals 16A, 16B in a mean value generator 16C (not shown here) ) are converted into the previously mentioned signal 16.

The force F is determined by two force components together, on the one hand from a force component which is caused by the pressure forces generated by the fiber mat in the wedge gap between the feed plate and the feed roller and on the other hand from a force component which arises from the friction forces occurring in the wedge gap.

The total resulting force F _R (is equal to compressive force + frictional force) can be broken down into two components, namely a horizontal component F _H and a vertical component F _V. The vertical force component is relatively small, since the corresponding contributions of the pressure and friction forces point in opposite directions. This component thus changes only slightly when the density of the fiber template changes. In the case of the horizontal force component, on the other hand, the corresponding contributions of the pressure and friction forces add up, so that there is a pronounced dependency here between F _M and the change in density of the fiber template in the clamping gap area. This dependency is exploited according to the invention in that the strain gauges 90 are likewise placed essentially in a horizontal plane and thus most sensitively determine changes in density of the fiber template in the clamping gap area.

The optimal direction of the force F is roughly horizontal and can be determined by experiment. However, an approximation to this optimal direction is enough to make a sensitive measurement.

31 shows that the force F acting on the pivot axis 11 should be in approximately the same direction, but not necessarily in the same plane as the force F _H.

However, this type of measurement also represents a significant difference from the prior art, in which a relative movement between the feed plate and feed cylinder is used for the measurement. In the latter case, the compressive forces increase with increasing density of the fiber template, but so do the frictional forces, which are due to the indispensable curvature of the food plate around the feed cylinder work against the pressure forces so that the measurement cannot be carried out sensitively. It is also not possible in the prior art to overcome this problem by measuring the relative movement in the horizontal plane; a relative movement is quite undesirable here, since the changing width of the clamping gap would make the control of the speed of the rotatable feed cylinder much more difficult.

Of course, the horizontal direction is only the preferred direction for the force measurement if the card is designed as in FIG. 1. With a differently designed angular position between the fiber feed means 2 and the licker-in roller 3 (ie approximately the inclination of a plane that the Axes of rotation of the feed roller 9 of the licker-in roller 3 connects to the horizontal plane), the direction of force had to be chosen accordingly.

With FIGS. 32 and 33 it is enlarged and thus shown in more detail than with FIG. 5 that the surface 39 with the strain gauges 90 is the flat base surface of a bore 91 and that by means of a further bore 92, which is arranged in mirror image relative to the aforementioned bore 92 emerges as the weakest point. This measurement practice is known in the art and is used, for example, by the Reglus firm in Adliswil, Switzerland.

33 also shows the compensation forces F _K1 and F _K2 arising as a result of the force F. The forces F and F _{K1 act in} such a way that the strain gauges 90 essentially reflect the transverse forces in the web 93.

The aforementioned forces are neither shown in the correct proportion nor in the exact direction.

The force measurement method described above also applies to the elements of FIGS. 6 and 7 to be described. FIG. 7 shows the feed plate 29, the pivot axis 31 and the bearing housing 30 as well as a second bearing housing 30.1 which also receives the pivot axis 31 as a floor plan of FIG. 6.

The feed plate 29 has two bearing legs 40 which receive the pivot axis 31.

In an analogous manner, as described for FIGS. 4 and 5, the pivot axis 31 has in the spaces between the bearing legs 40 and the bearing housings 30 and 30, respectively. 30.1, each have a surface 39 for receiving a strain gauge (not shown).

The strain gauges for this variant are also arranged in such a way that they each generate a signal corresponding to the magnitude of a force F.1 (FIG. 6) generated during operation on the feed plate 29, with both signals in a mean value generator (not shown) in the Signal 16 mentioned earlier can be converted.

The force F.1 builds up in an analogous manner to the force F described for FIGS. 4 and 5.

The optimal direction of the force F.1 is also determined by experiments, an approximation to this optimal direction also being sufficiently precise.

The following FIGS. 8 and 9, 12 and 13, 16 and 17, 20th and 21, as well as 24 and 25, with the exception of the measuring means for determining the signal 16, show the same elements as were shown with FIGS. 4 and 5, for which reason the same reference symbols are used for the same elements. The same applies to the following FIGS. 10 and 11, 14 and 15, 18 and 19 and 22 and 23 with respect to the elements shown in FIGS. 6 and 7.

The measuring means of FIGS. 8 and 9 is a load cell 41 assigned to the adjusting screw 12 such that it outputs a signal 16 corresponding to the size of a force F.2 (FIG. 8). This force F.2 is a force resulting from the forces generated in operation by the fiber mat 15 (not shown in FIG. 8) in the clamping gap region 23, which acts in the direction of the longitudinal axis (not shown) of the adjusting screw 12. The set screw 12 is arranged in the middle of the length L of the feed plate 10. The horizontal distance H, as seen in FIG. 8, of the above-mentioned longitudinal axis up to the fiber delivery 24 is not particularly critical, nevertheless the smallest possible distance H should be aimed for.

The same applies to a load cell 41.1 assigned to the set screw 32 (FIG. 10), to which a force F.3 acts analogously to the force F.2 of FIG. 8. Also, the set screw 32 is in the middle of the length L and with a horizontal distance H.1, as viewed in FIG. 10, from a fiber deflecting nose 44 on the feed plate 29 to that in the direction of the longitudinal axis (not shown) Set screw 32 acting force F.3.

Fig. 12 respectively. 13 and 14 resp. 15 each show a variant in the use of load cells to determine the density of the fiber mat in the wedge gap area 23 or. 23.1 (not shown in FIGS. 12 and 14) force generated during operation.

For this purpose, the dining plate 10 of FIGS. 12 and 13 in the end face 42 facing the beater 3 (FIG. 2) has a depth T and a height B (FIG. 12) having groove 43. The height B is selected in such a way that load cells 41.2 can be pushed into the groove 43 without play in a position shown in FIGS. 12 and 13 and held in place (not shown).

In operation, the fiber mat 15 (not shown in FIG. 12) located in the wedge gap between the feed plate 10 and the feed roller 9 generates forces which tend to have a feed plate part 60 located between the groove 43 and the fiber-dispensing edge 24 around an inner groove edge 61 to pivot in a direction R. These forces result in a force F.4 acting over the entire length L, which generates a corresponding signal in the load cells 41.2. The signals of the individual load cells are averaged to signal 16 in an averager (not shown).

The variant shown with FIGS. 14 and 15 functions with respect to the generation of the signal 16 essentially the same as described with reference to FIGS. 12 and 13, which is why it is for the generation of the signal 16 necessary elements are provided with the same reference numerals as in FIGS. 12 and 13, with the exception of the force F.5, which already has a different size than the one because of the different type of fiber transfer via the nose 44 of the feed plate 29 to the briseur 3 Force F.4 of FIG. 12, in which the fibers are transferred in a so-called synchronous fashion from the feed roller 9 to the beater 3. The synchronism arises from the fact that the feed roller 9 and the beater 3 have the same direction of movement at the fiber transfer point (see FIG. 1). However, other factors can play a role in the formation of the force component F.5, such as the shape of the food plate 10 or. 29 in the area 23 resp. 23.1 and the distance of the groove edge 61 from the fiber mat 15 leading surface of the food plate 10, respectively. 29. Likewise, the invention is not restricted to the number and arrangement of the load cells shown in FIGS. 13 and 15. It is understood that, for example, depending on the strength of the groove 43 to the fiber release edge 24 (FIG. 12) or. up to the nose 44 (FIG. 14) extending plate part, one, two or more load cells 41.2 can be provided.

16 and 17, the measuring means consists of three load cells 41.3 which are arranged in a groove 45 which is embedded in the feed plate 10 and opens into the clamping gap region 23 (FIGS. 1 and 2) in the clamping gap.

In order to transmit the force component F.6 generated by the fiber mat located in the clamping gap and acting over the entire length L to the load cells 41.3, these load cells are transmitted by a force gungsbalken 46 covered, which closes the groove 45 completely and without any disturbing deflection of the shape of the food plate completely adapted.

The signals emitted by the individual load cells 41.3 are converted into signal 16 in an averager (not shown).

The distribution of the aforementioned load cells in the groove 45 is essentially as shown in FIG. 17. However, it is understood that the number of load cells is not limited to the three shown. For example, in the case of a force transmission bar designed with a corresponding strength, only two load cells can be used, while if a more precise determination of the force components over the length L (FIG. 17) of the feed plate 10 is to be carried out, a larger number of load cells can be distributed.

18 and 19 is composed of a membrane 47 inserted into the feed plate 29, a pressure converter 48 and a pressure fluid system 49 connecting the membrane 47 to the pressure converter 48.

A force component F.7 (FIG. 18) analogous to the force F.6 of FIG. 16 causes a pressure on the diaphragm 47, as a result of which a force transmission is transmitted via the hydraulic fluid system 49 to the pressure converter 48, which is a force F. 7 corresponding signal 16 is generated.

20 and 21 is based on the Recognition that when the fiber mat 15 is inserted into the wedge gap between the feed plate 10 and the feed roller 9, ie into the wedge gap region 23, air is displaced from the fiber mat due to the increasingly narrowing clamping gap.

The displacement of this air is opposed by the resistance of the fiber mat itself, so that an increasing overpressure in the fiber mat arises in the fiber mat 15 in the direction of the fiber delivery edge 24, the resistance of the density of the fiber mat and the amount of air to be displaced correspondingly different.

This overpressure is detected with the measuring means shown in FIGS. 20 and 21, in that a measuring groove 50 is let into the food plate 10, which is connected to a pressure transducer 53 within the food plate 10 via a pressure line 51 and a pressure line 52 connected to the food plate 10 is. This pressure converter 53 converts the excess pressure determined in the measurement groove 50 into the signal 16.

21, the measurement groove 50 is not continuous over the entire length L, i.e. the length L.1 of the measuring groove 50 is shorter than the length L of the feed plate 10, so that the measuring groove 50 is a groove located in the clamping gap area 23 and only open against the clamping gap.

As shown in FIG. 20, the measurement groove forms an acute angle α with an imaginary plane E, which includes the mouth edge 54 of the wall 55 of the groove 50 as a tangential plane. This arrangement prevents that a fiber jam occurs in the groove 50. The angle α has a maximum of 30 degrees.

22 and 23 show one of the measurement grooves 50 of FIGS. 20 and 21 analog measurement groove 50.1 with a pressure line 51.1 connected to it and a pressure line 52.1.

In contrast to the measuring means of FIGS. 20 and 21, the measuring means of FIGS. 22 and 23 not only measure the pressure which, as described, arises from the pressing out of the air from the fiber mat, but it also becomes a constant one from a compressed air source 56 The amount of compressed air is pressed into the compacting fiber mat using measuring groove 50.1. This predetermined amount of compressed air is passed through the fiber mat against the resistance of the fiber mat, so that a pressure corresponding to this resistance is transmitted from the pressure lines 51.1 and 52.1 to a pressure transducer 53.1 connected to the pressure line 52.2.

Since the resistance changes with the density of the fiber mat in the clamping gap area 23, the pressure in the lines 51.1 and 52.1 also changes. The pressure converter 53.1 converts these pressure variations into the signal 16.

As can be seen from FIG. 22, the measurement groove 50.1 also has the angle α described for FIG. 20.

FIGS. 24 and 25 show a variant of the measuring means of FIGS. 22 and 23, in that the quantity of compressed air which remains constant from the compressed air source 56.1 by means of an on Blow groove 58 is blown into the fiber mat located in the wedge gap area 23. This air travels in this fiber mat in a direction W opposite to the direction of rotation of the feed roller until it can escape into the atmosphere through a ventilation groove 59 and a ventilation line 57 connected to it.

A pressure transducer 53.2 is connected to the pressure line 52.2. This pressure converter 53.2 converts the pressure existing in the pressure line 52.2 into the signal 16. A resistance range can be defined with the distance M between the injection groove 58 and the ventilation groove 59.

FIGS. 26 and 27 show a variant 2.2 of the fiber feed means from FIG. 2, in that the feed plate 10 can not only be pivoted about the pivot axis 11, but that it can also be pivoted about a pivot axis 62, which is coaxial with the axis of rotation of the feed roller 9 lies. This pivotability is shown schematically with the radius arrow S.

In order to enable this pivotability, a holding bracket 63 is provided which has two legs 64 (only one visible in FIG. 26), in which the pivot axis 11 is mounted.

These legs are connected to a web 65 which is continuous under the food plate 10 (viewed with a view of FIG. 26) and serves to receive the stop 27.

Furthermore, the legs 64 each have a guide slot 66, the lower guide surface 67 (with 26)) has a curvature with the radius S. The upper guide surface 68 opposite the lower guide surface 67 is provided parallel to the guide surface 67.

These guide slots 66 each serve to receive two guide pins 69, which are fixedly arranged in a machine housing part 70. The distance (not marked) of these two guide bolts 69 is selected in relation to the length (not marked) of the guide slot 66 such that the holding bracket 63 can be pivoted about the pivot axis 62 for a given pivot length (not marked).

In order to hold the holding bracket 63 in a selected pivot position, it is held in place by means of two screws 71 screwed into the machine housing part and projecting through the guide slot 66.

Furthermore, the set screw 12 is arranged on an end part 63.1 of the holding bracket 63 directed against the licker-in roller 3.

It goes without saying that this variant can also be used to combine all of the elements shown in FIGS. 4 to 25 in order to generate the signal 16. The application of these elements in connection with this variant is therefore not repeated.

28 and 29 show a variant 2.3 of the feed means of FIG. 3, in that a feed plate 72 is fixedly connected to the machine housing 25, while the feed roller 9 is movable in a given area.

This mobility of the feed roller 9 is given by the fact that the free ends 73 of the feed roller 9 projecting on both sides (only one shown with FIG. 28) of the feed roller 9 are accommodated in a bearing bush 74, which is between two stationary sliding guides 75 and. 76 are guided.

The displacement range of the feed roller 9 is limited on the one hand by a stationary stop 77 and by an adjusting screw 78 which is received in a carrier 79 which in turn is fastened to the machine housing 25. The stop 77 has the same function as the stop 27 described earlier.

In operation, the fiber mat 15 on the feed plate 72 is slidably moved from the feed roller 9 into the wedge gap between the feed roller 9 and the feed plate 72, whereby the feed roller 9 from its starting position, in which the bearing bushes 74 each rest on the corresponding stop 77, until they enter the operating position are raised, in which the bearing bushes 74 each abut the adjusting screws 78.

It goes without saying that with the variant shown with these figures, the elements shown with FIGS. 8 to 25 can be used to generate the signal 16.

30 shows a drafting system in which the method described so far is also used. In this variant 2.4 of the feed means, a counter roller 101 is used instead of the feed plate 10 shown in FIG. 1. This counter roller 101 forms together with the Feed roller 9 the nip.

In contrast to the feed roller 9, the counter roller 101 is not driven, i.e. is freely rotating and is dragged through the fiber mat 15 lying between the counter roller and the feed roller.

The counter roller 101 is rotatably attached to a pivot lever 102.

The other elements known from the description for FIG. 1, which can be used in an analogous manner in this variant, are accordingly provided with the same reference numerals. It follows that, for example, the pivot lever 102 is pivotally mounted by means of the pivot axis 11 and the bearing housing 26.

The load cell 41 described with FIGS. 8 and 9 is used as the measuring means for generating the signal 16. Reference is therefore made to the description for FIGS. 8 and 9.

The roller pairs identified by reference numerals 103 and 104 are very well known from drafting technology and are therefore not described further. It should only be mentioned in connection with the function of the feed means that the two lower rollers (seen with a view of FIG. 30) of the roller pairs 103 and 104 are driven at a fixed speed which results in the draft in the drafting system. The upper rollers of the roller pairs 103 and 104 are also dragged from the fiber mat in an analogous manner to the roller 104.

The draft ratio of the spinning machine shown with this figure lies between the peripheral speed of the feed roller 9, given by the speed of the geared motor shaft 21 and the peripheral speed of the lower roller 104, given by its speed generating the speed signal 19.2. The signal 19.2 has the same function as the signal 19 of FIG. 1.

Furthermore, the device 110 for determining the density of the fiber sliver, which is known from EP-A-0 078 393 and is known from EP-A-0 078 393, is provided immediately after a fiber compression funnel.

This device 110 is a pair of rollers that can be pressed against one another, the peripheries of which engage in one another in such a way that a time-limited clamping zone that guides the sliver is created. One roller 113 is stationary and the other roller 114 is arranged to be movable in order to carry out a movement corresponding to the fluctuations in the density of the sliver. In the practical application of this device, these movements are sensed by a so-called proximity switch (not shown) and the signal 111 corresponding to the density fluctuations is generated.

Instead of a proximity switch, as a variant (shown with dashed lines) the movement of the roller 114 can be limited in a manner analogous to the counter-roller 101 by an adjusting screw 12.1 provided with a load cell 41. For this purpose, the roller 114 is rotatably mounted on a pivot lever 115 which functionally corresponds to the pivot lever 102, while the pivot lever 115 is pivotally mounted by means of a pivot axis 11.1 in a bearing housing 26.1 fixedly arranged on the machine housing 25.

In operation, the sliver 8 opens the rollers 113 and 114 by a predetermined amount (not marked), i.e. until the pivot lever 115 is in contact with the set screw 12.1. The resulting different forces in the fixed nip of the rollers 113 and 114, corresponding to the different density of the sliver 8, are detected by the load cell 41 and sent to the controller 17 as a signal 116.

Elements that have the same functions as previously described have the same reference numerals.

An advantage of the inventive setting of the clamping gap to the density of the intermediate fiber mat 15 and. To measure the intermediate sliver 8, compared to the known measurement of the clamping gap width changed by said density, is that the measurement signals have a correspondingly large amplitude due to the intense force variations.

Another advantage is that the hysteresis inherent in the displacement measurements is eliminated in the force measurement.

Claims (30)

1. A method for automatically compensating for tape density fluctuations in textile machines, such as cards, draw frames and the like, in which at the entrance of the textile machine one of the density of a resp. one in a feed means (2; 2.1; 2.2; 2.3; 2.4) fiber wadding (15) resp. Sliver (15.1) dependent signal (16) and at the output of the textile machine a signal (111; 116) depending on the density of a sliver (8) located in a device (110) for determining the density of a sliver is generated, and in which these signals (16 and 111; 116) are used to influence the feed rates as a function of the two signals (16 and 111),
characterized,
that at least the feed means (2; 2.1; 2.2; 2.3; 2.4) has a preselected clamping gap that remains the same during operation and that the signal (16) is obtained in this clamping gap depending on the fiber density. 2. The method according to claim 1,
characterized,
that the said device (110) additionally has a preselected clamping gap which is stationary during operation and that the signal (111; 116) is obtained as a function of the fiber density in this clamping gap. 3. The method according to claim 1,
characterized,
that the feed means (2; 2.1; 2.2; 2.3; 2.4) ei ne feed roller (9) and a cooperating feed element (10, 29, 63, 72, 101) and that the feed speed is the speed of the feed roller (9). 4. The method according to claim 3,
characterized,
that the feed element contains a feed plate (10, 29, 63, 72). 5. The method according to claim 3,
characterized,
that the feed element contains a freely rotating counter roller (101). 6. The method according to claim 1,
characterized,
that the signal (16) is obtained from the resistance, which is opposed to an air flow caused by the fiber mat (15) or. Sliver (15.1) flows. 7. The method according to claim 6,
characterized,
that the air flow by displacing the air against the narrowest point of the clamping gap moving fiber mat (15) or. Sliver (15.1) is generated. 8. The method according to claim 7,
characterized,
that the airflow is additionally through a against the narrowest point of the clamping gap moving fiber mat (15) resp. Sliver (15.1) is blown airflow generated. 9. The method according to claim 6,
characterized,
that the signal (16) is generated from the resistance of a part of the wadding section located in the clamping gap. 10. The method according to claim 4 and 9,
characterized,
that the wadding section is given in the circumferential direction of the feed roller by a predetermined distance and by the length of the feed roller. 11. The method according to claim 2 and 5,
characterized,
that the signal is obtained from a force generated by the fiber density in the clamping gap. 12. The method according to claim 11,
characterized,
that the force is mechanically transmitted to a force measuring device in which an electrical signal is generated. 13. The method according to claim 11,
characterized,
that the force is transmitted hydraulically to a force measuring device in which an electrical signal is generated. 14. The method according to the preceding claims,
characterized by
that the signals (16 and 111) are evaluated in a controller (17) into a signal (22) controlling the speed of the feed roller (9). 15. Device for carrying out the method according to claim 1,
- With a feed means (2; 2.1; 2.2; 2.3; 2.4), which is a drivable, the fiber mat (15) or. Includes sliver (15.1) feed roller (9) in the textile machine and a feed element (10, 29, 63, 72, 101) that interacts with this feed roller and thereby forms a clamping gap for the fiber mat, as well as with a device (110) at the exit of the Textile machine which contains a drivable roller (113) which conveys the sliver (8) from the textile machine and a free-running roller (114) which cooperates with the latter and forms a clamping gap for the sliver (8) and
- Each with a measuring device to determine the density of the incoming fiber mat (15) or. the incoming sliver (15.1) as well as the passing sliver (8) and output of a measurement signal corresponding to the respective density (16 or 111; 116),
characterized,
- That at least the feed roller (9) or
- The feed element (10, 29, 63, 72, 101) is movable from an initial position into an operating position, which by
- An adjustable actuator (12, 78) is given, while the feed element (10, 29, 63, 72, 101) or the feed roller (9) is stationary in order to form a constant clamping gap between the feed roller (9) and the feed element during operation. 16. The apparatus of claim 15,
characterized,
that in addition said free-running roller (114) can be moved from an initial position into an operating position, which is given by an adjustable actuator (12.1), while the drivable roller (113) is stationary in order to maintain a stationary clamping gap between the two aforementioned rollers (113 and 114). 17. The apparatus of claim 15,
characterized,
that the feed element (10, 29, 63) comprises a feed plate (10, 29) which can be pivoted about a pivot axis (11, 31) and the adjustable actuator comprises at least one adjusting screw (12) against which the feed plate for limiting the clamping gap is in operation . 18. The apparatus according to claim 15,
characterized,
- That the feed element includes a stationary feed plate (72) and
- That the feed roller (9) is movable from an initial position into an operating position, which is given by an adjustable actuator (78). 19. The apparatus of claim 15,
characterized,
that the feed element comprises a counter roller (101) which can be pivoted about a pivot axis (11) and the adjustable actuator comprises at least one adjusting screw (12) which limits the pivoting movement of the counter roller (101) in order to limit the clamping gap. 20. The apparatus according to claim 16,
characterized,
that the free-running roller (114) is arranged to be pivotable about a pivot axis (11.1) and the actuator comprises at least one adjusting screw (12.1) which limits the pivoting movement of the free-running roller (114). 21. The apparatus according to claim 17,
characterized,
that the measuring means are two strain gauges (not shown) which are attached to the swivel axis at a distance from one another and which determine the transverse force caused by the feed plate in the swivel axis and give a corresponding electrical signal (16). 22. The apparatus of claim 17, 19 or 20,
characterized,
that the measuring means is at least one load cell (41, 41.1) which, as part of the set screw (12, 12.1, 32), determines the force generated in the clamping gap and delivered to the set screw (12, 12.1, 32) and a corresponding electrical signal (16 ) results. 23. The device according to claim 17 or 18,
characterized,
that the measuring means is at least one load cell (41.2) which is inserted without play in a groove (43) provided in the feed plate (10, 29) in such a way that the force generated in the clamping gap is transmitted to the load cell (41.2) at least in a proportional proportion and this results in a corresponding electrical signal (16). 24. The device according to claim 17 or 18,
characterized,
that the measuring means are at least two load cells (41.3) which rest on the base of a groove (45) provided in the feed plate (10) and opening into the clamping gap and are covered by a force transmission bar (46) resting on these load cells (41.3), which, with its surface directed towards the clamping gap, forms part of the surface of the feed plate forming the clamping gap, in such a way that the force transmitted from the force transmission bar (46) to the load cells (41.3) results in a corresponding electrical signal (16). 25. The device according to claim 17 or 18,
characterized,
that the measuring means firstly comprises a membrane (47) which is integrated essentially over the length of the feed plate (29) in the surface forming the clamping gap and secondly includes a pressure transducer (48) on which the force taken over by the membrane (47) is transmitted hydraulically and which emits a corresponding electrical signal (16). 26. The device according to claim 17 or 18,
characterized,
that the measuring means has a groove (50), which is provided in the food plate (10) and opens into the clamping gap and extends essentially over the length (L) of the food plate, parallel to the pivot axis (11) of the food plate (10), and also a groove of this groove connected pressure transducer (53), wherein the groove (50) with the groove wall (55) facing the pivot axis with the clamping gap surface of the feed plate (10) encloses an angle of at most 30 angular degrees and that the pressure transducer (53) a the pressure in emits the corresponding signal (16). 27. The apparatus of claim 17 or 18,
characterized,
that the measuring equipment
- A provided in the feed plate (29), opening into the clamping gap, extending essentially over the length (L) of the feed plate (29), parallel to the pivot axis (31) of the feed plate (29) or to the axis of rotation of the feed roller (9) arranged groove (50.1),
- and a pressure transducer (53.1) connected to this groove (50.1),
- and also contains a compressed air source (56) connected to the groove (50.1) with a constant amount of compressed air,
- The groove (50.1) with the pivot axis (31) facing the groove wall (55.1) with the clamping gap surface of the dining plate encloses an angle of a maximum of 30 degrees and
- The pressure transducer (53.1) emits a signal (16) corresponding to the pressure in the groove (50.1). 28. The device according to claim 17 or 18,
characterized,
that the measuring means have a first and a second, each provided in the feed plate (10), each opening into the clamping gap, extending essentially over the length (L) of the feed plate (10), parallel to the pivot axis (11) of the feed plate (10 ) arranged groove, the first groove being a blow-in groove (58) and the second a ventilation groove (59) and both grooves with their groove wall facing the pivot axis enclose an angle of a maximum of 30 degrees with the clamping gap surface of the dining plate and,
that the first groove is provided at a predetermined distance (M) away from the second groove, and
that the first groove (58) is connected to a compressed air source (56.1) of constant air volume and to a pressure converter (53.2) which emits a signal (16) corresponding to the pressure, while the second groove (59) is connected to the atmosphere. 29. Device according to the preceding claims 15 and 17,
characterized,
that the pivot axis (11) of the feed plate (10) can be pivoted and locked in a predetermined range around the axis of rotation (62) of the feed roller (9). 30. The method according to claim 3, characterized in that the signal is determined close to, but before that point at which the feed element transfers the fiber mat to the element receiving the fiber mat.

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