DE1097328B - Method and device for automatic regulation of the warpage of the fiber slivers in drafting units or the like. - Google Patents

Description

The invention relates to a method and a device for automatically regulating the delay od the slivers in drafting devices. Like. In which one or more slivers by an electrical Measuring capacitor are performed, the capacitance value of which is related to the weight per unit length of the tested section of the sliver or a plurality of slivers changes, whereupon these changes in capacitance are transformed into changes in a first electrical quantity and to form a second electrical quantity can be used as the electrical mean value of the first electrical quantity, whereupon this said second electrical quantity is subtracted from the said first electrical quantity, so that a third electrical quantity is obtained, is the now the deviations in the weight of the section currently located in the measuring capacitor of the sliver or several slivers of which corresponds to the mean value over a certain length, given by the duration of the formation of the mean value from the first electrical quantity is whereupon this third electrical quantity becomes more sufficient according to its magnitude and polarity Gain regulates the angular speed of a pair of drafting rollers.

In the spinning mill there is a need for automatic control of the draft of the slivers in Drafting devices or the like with the purpose of preventing the undesired - with previously known drafting devices or drafts unavoidable - to automatically regulate weight fluctuations in ribbons and rovings. Acquaintance Control systems of the usual type, however, cannot easily be integrated with processing machines the spinning mill, since a number of difficulties arise here.

The technology already knows methods and devices for automatic control of weight per unit length of sliver or roving. These procedures are initially carried out with the help of electrical Measuring capacitors or optically or pneumatically measured the weight per unit of length. On that becomes a corresponding to the current weight per unit length of the unregulated sliver Signal compared with a signal corresponding to the nominal value and the resulting difference used as a control signal to regulate the delay.

All of these known methods have the major disadvantage that they rely on absolute stability over time the electrical, optical or pneumatic measuring devices are dependent. Its available today Standing measuring elements of this type do not have sufficient stability in this regard. The over long time intervals unavoidable instability of the method and device in practice

to automatically regulate the delay

of the slivers in drafting units or the like.

Applicant:

Zellweger A. G. Apparatus

and machine works Uster,

Uster (Switzerland)

Representative: Dr.-Ing. RK Löbbecke, patent attorney,
Berlin-Zehlendorf, Neue Str. 6

Claimed priority:
Switzerland from January 9, 1958

Hans Locher, Uster, Zurich (Switzerland),
has been named as the inventor

the measurement of the weight of the sliver now has a very unfavorable effect on the control process. The said Instability has the consequence that the mean weight per unit length of the drawn sliver no longer corresponds to the desired setpoint after a certain period of time.

It is possible to check the adjustment of the measuring element by means of relatively frequent checks. That Sliver or several folded slivers must be completely removed from the measuring element, so that the adjustment that was originally set when the measuring element was emptied is readjusted again can be. However, these frequent checks mean an unacceptable amount of additional work Work for the operating staff, so that experience has shown that these regular checks are neglected will.

With the known electrically, optically or pneumatically operating control systems, after The short-term deviations are corrected for what has been said, but at the same time they bring that Disadvantage that the long-term fluctuations in thickness in the sliver are increased. Such However, changing the average weight or the "number" of the ribbons or roving is allowed under no circumstances, as this would have devastating consequences in the spinning mill.

The known electrical, optical or pneumatic control methods are therefore unsuitable in practice.

009 698/77

suitable, since the gain in uniformity obtained by regulating the short-term fluctuations is faced with an intolerable loss in relation to long period weight fluctuations. A method of the type mentioned has now already been proposed which is suitable for the to overcome some of the disadvantages described.

The mentioned method is based on the known fact that the slivers and rovings of the spinning mill very strong proportions of short-period irregularities in weight per unit of length, less contain strong proportions of fluctuations with a medium period length and only minor proportions of long-period fluctuations. It is therefore no disadvantage if only the considerable ones due to the automatic control device in slivers and rovings Fluctuations in short and medium period lengths are compensated for, along with those in and of themselves even insignificant fluctuations with a long period cannot be corrected.

According to the method or with the corresponding devices of the type mentioned above, Achieve much better regulations of the delay, since all rule errors are long duration, which exclusively are caused by interference from the measuring elements themselves, are switched off and, moreover, no danger exists that the average weight of the tape is changed in an inadmissible manner. That mean weight of the tape or roving is yes over great lengths by the appropriate feeding devices kept constant in the previous work processes.

Although this method and the corresponding device allow only the most intensive Fluctuations with short and medium period lengths can be compensated without losing the average weight There are still some fundamental difficulties to endanger through measurement inaccuracies and interference exist. A first such difficulty is that it can be done with the help of said facilities is not possible, in the first moment after switching on the controlled system, a correct one immediately To achieve regulation. After such a machine is shut down, the second electrical one is activated Size exactly to the value of the first electrical size, which is a disadvantage in that when the machine is switched on again, the second electrical variable dem after a certain time Corresponds to the mean value of the first electrical variable over a certain period of time. Another disadvantage lies in the fact that the time constant, which is the length of time for the formation of the mean value of the first Determined electrical size, must be chosen so that the necessary switching elements are very extensive will.

Another method and a corresponding device for compensating for changes in cross-section when drawing slivers is already known. According to this procedure, the The cross-section of the sliver or roving 6q is initially variable due to mechanical scanning electrical signal generated. This variable electrical signal is transformed into a Dynamo machine alternately fed to two integrators. One of these integrators saves the electrical quantity output by the dynamo machine during a certain time interval, while the other integrator uses its stored value as the mean value for the within the same time interval Provides formation of an electrical difference variable.

The time intervals for storing and removing the electrical value commutates from the integrators. This arrangement also suffers from the disadvantage that the integrators discharge themselves when the system is at a standstill and only during a certain period when the system is commissioned Time to recharge. Only when they are charged can they function as To meet mean value memory. Until this state is reached, however, there is "a regulation of the delay not possible. Another disadvantage is seen in the fact that the averaging jumps between the alternating effective integrators takes place. This can reduce the electrical differences between the individual sections of the sliver also by sudden changes in the electrical Sizes lead to incorrect control effects.

The present invention is based on the object of avoiding these disadvantages in the method and device of the type mentioned at the beginning. The invention consists in the fact that the second electrical variable is continuously formed in that a differential speed is formed from the first variable speed proportional to the speed of the first drafting roller pair used to draft the sliver and from the second constant speed of the intake roller pair by means of a differential gear or the like which then has the value zero when the speed of the drafting roller pair has that value which corresponds to the desired average draft of the drafting system, whereupon this difference speed is reduced to a reduced speed, the shaft having this reduced speed in a time interval i ₂ - t _i passes from a first angular position a _± into a second angular position a ₂ , the difference A α of which is an integral value

Δα = 2π fn ₅ - dt

represents that -i from over a time interval At t _{2 x} after the time integrated difference is formed rpm course, whereupon the the integral value Aa representing angular difference a ₂ - a _t by means of a mechanical-electrical converter in a their equivalent electrical voltage change is converted , which represents the second electrical quantity as an electrical signal.

The present invention also relates to an apparatus for carrying out the method and is characterized by a differential gear to which a variable, a speed of a drafting roller pair communicated proportional speed and a constant speed of a pair of feed rollers and in which the differential speed from the variable speed and the constant speed is formed, further by a reduction gear to reduce the differential speed to a Speed, further by a mechanical-electrical converter controlled by the latter for generation of an electrical signal as a second electrical quantity, which only run very slowly Changes in a first electrical quantity follow.

With reference to the drawings, for example, a device for performing the inventive Procedure explained. It shows

Fig. 1 schematically the. Formation of a delay field of a controlled system with the control device according to the invention;

Fig. 2 shows a variant A of the device; Fig. 3 shows a further variant B, and

FIG. 4 shows a third variant C of the device according to FIG. 1.

1, the sliver 9 or a number of adjacent slivers - for the sake of simplicity of the description, only one sliver is mentioned in the following - is represented by a pair of drafting rollers 7, 8 in _{rotating at a constant speed M 2}

wheel 13 stand still as long as the speeds W ₁ and W ₂ are equal to each other. Changes in the first variable speed M ₁ compared to the constant second speed M ₂ consequently result in a possible movement of the gear wheel 13 and the gear wheels 14 and 15 connected to it in both directions of rotation of the reduction gear 14, 15 following the gear wheel 13, which in 1 is drawn, for example, as a simple spur gear.

Direction of the arrow through the measuring capacitor or the like. Hin- io The purpose is that a certain number of moved. This gives the weight of the mo revolutions of the cage 12 'of said differential gear 12 are reduced so far that the tap 17 designed as a grinder on the gear

berad 15 of the following mechanical-electrical converter

mentan located in the said measuring capacitor
Sliver proportional control signal U ₁ , which the
represents the first electrical variable, via a phase shifter 30 serving the time delay to a 15 16 for the reversing electrical compensator 2 possible in practical operation, which also describes a hang of the cage 12 'at most the entire angular arc a _{0 of} the mechanical-electrical converter 16. The size of the reduction ratio

second electrical variable U _{3 is} supplied from the mechanical-electrical converter 16. The mentioned compensator 2 forms from the control signal U ₁

between the gears 14 and 15 determined

and the second electrical variable U _3, the electrical 20 - as will be explained below - the time constant of the differential _{variable CT 4} , which represents the third electrical variable of the control process and is therefore advantageously displayed. This is carried out via an electrical bar. This time constant is characterized more 3 to the electric-mechanical power concluded that for a possible change of the second converter 4. This electro-mechanical power electrical magnitude U ₃ by the amount Δ U ₃ the tap converter 4 grants the pair of drafting rollers 5, 6 one in 25 17 from the position α to the position α = α + Δα

Mean compared to the constant speed M _{2 of} the drafting roller pair 7, 8 by 10 to 50% higher speed n _s . This mean speed n ₃ then occurs

has to move on. An inherently identical change in angle Δα requires more time, the greater the reduction between the differential speed M ₄ assumed to be constant and the reduced differential

when the drafting roller pair 5, 6 on the sliver 9

the desired average delay of the delay speed M _{5 is} selected.

systems. However, if the weight is per length in connection with the gear 15 is the

Unit of the belt 9, for example, higher than the tap 17 of the electrical-mechanical converter 16,

called mean value, the measuring capacitor 1 gives a which is designed as a potentiometer, for example

increased control signal U ₁ , which is more suitable. The position of the tap 17 closes with his

Formation of the electrical compensator 2, the Ver 35 end position at terminal 19 the angle α, the one

amplifier 3 and the electrical-mechanical power partial voltage U ₃ of that on the mechanical-electrical

Converter 4 an increased speed n _{3 of} the drafting roller pair 5, 6 occurs. The delay occurring between the drafting roller pairs 5, 6 and 7, 8 is increased in such a way that the sliver 9 exiting after the drafting roller pair 5, 6 again has the same desired weight per unit length as in the case of the average draft with average weight per unit length of the tape .

If, on the other hand, a point of the sliver passes through the capacitor 1 which is too light compared to the average weight per unit length, the control signal U _{1 of} the measuring

Transducer 16 voltage U ₂ determined according to the voltage divider equation:

U _a = U,

a ₀

initially too thin point in the sliver 9 therefore suffers a less severe distortion, and that after the pair of drafting rollers 5, 6 emerging sliver

In the run-in operating state, the angle α is set in such a way that the output voltage U ₃ corresponds approximately to the control signal U ₁ supplied by the measuring capacitor 1. The tap 17, however, follows the movements of the gear wheel 13 with an angular speed reduced by the reduction ratio formed between the gear wheels 14 and 15.

capacitor 1, whereby the speed of M ₃ of the comparison 50 Here, for example slows 6 The time interval originally zfi = f ₂ is produced in a particular zugswalzenpaares 5, - t _t between the positions of the

Tap 17 at the time instant t _t up to the time instant L _{2 is} an angular shift around the value. This angle Δ α represents the integral value of the changed again has about the desired mean weight 55 sary speed M ₅ about this time interval At = to per unit length. t ₂ - t _t , namely

The variable speed n _{3 of} the drafting roller pair 5, 6 is determined by means of the gear 10, 11 in
one reduced by the average delay factor and
therefore a 60 comparable to the constant speed M ₂
first variable speed M ₁ transformed. The so
The first variable speed M _{1 obtained} and the constant second speed n ₂ are placed in a differential pensator 2.

formed by supplied. This difference calculator is in accordance with In the case of normal, undisturbed operating conditions

1 designed as a differential gear 12. It can cause 65 des that in its weight per length, however, a planetary gear can also be used. That is, fluctuating sliver 9 short-term fluctuating The differential gear 12 forms the algebraic effects around a mean value of the control signal U ₁ . The difference between the two effective speeds M ₁ and M ₂ . The difference U ₄ occurring in this case causes the cage 12 'of the differential gear 12 and the consequent high, but short-term accelerations and the cage 12' mentioned, 70 delays of the drafting roller pair 5, 6 and so on.

"2

Δα = 2π fn ₅ · dt. H

As mentioned at the beginning, the voltage U ₃ forms the second electrical quantity that is applied to the electrical grain

with movements of the cage 12 'of the differential gear 12 in both directions of rotation. The tap 17 of the mechanical-electrical converter 16 therefore only performs small changes in angle Δ α around the position α.

If the capacitor 1 or a part of it is subjected to a long-term disturbance, this causes the following control processes:

The control signal U _{1 of} the measuring capacitor 1 changes with respect to the voltage U _s emitted by the mechanical-electrical converter 16, for example ίο in a positive sense. The result is a positive difference voltage U ₄ at the output of the compensator 2 and an increased speed of the drafting rollers pair 5., 6. This results in the differential gear 12 a rotational speed Ji ₂ -W ₁ of the cage 12 'and n-zero speeds M ₄ and ₅ . The tap 17 therefore experiences an angular displacement + Δ a, as a result of which the voltage U _z increases. If the interfering influence continues, the control device continues to operate in the manner set out until the aforementioned interfering influence ceases to act.

But outweighs the strength and duration of the interference the time that the tap 17 needs to move out of its position corresponding to the angular amount α to get to one of the stops 20 and 21, the time of the reduction ratio of the Reduction gear 14, 15 depends, it is expedient one triggered when one of the stops 20 and 21 is touched, not shown in detail in FIG. 1 indicated alarm device actuated, which indicates the presence of a long-term malfunction indicates. It is also advantageous if the position of the tap 17 is made visible in every position, in order to be able to observe the correct operation of the control device at any moment.

For the correct operation of the device according to the invention, it is further advantageous if the control signal U ₁ obtained from the measuring capacitor 1 first passes through the phase shifter 30 which is known per se and which is used for the time delay. This time delay has the purpose of bridging the time difference resulting from the movement of the sliver 9 between the moment of measurement in the measuring capacitor 1 and the onset of the desired delay between the drafting roller pairs 5 _} 6 and 7, 8.

Another requirement for proper operation of the device according to the invention is the return of an auxiliary voltage U ₅ , which is proportional to the differential speed n _t and generated in a tachometer 31, to the compensator 2, whereby the load dependency of the drive of the drafting roller pair 5, 6 is switched off, as well as the linearity of the Control characteristics as well as other properties can be improved.

Three variants A, B and C of the automatic control device according to the invention are formed in FIGS. 2, 3 and 4 essentially analogously to the basic form described above with reference to FIG. 1, the same reference numerals being used for the corresponding parts.

The difference for variant A according to FIG. 2 is that the mechanical-electrical converter 16 with its terminals 18 and 19 is built directly into the electrical circuit of the measuring capacitor 1 and forms part of an electrical measuring bridge 26 with it, the position of the tap 17 of said mechanical-electrical converter 16 determines the respective bridge center point. The bridge voltage resulting from this arrangement reaches the amplifier 3 directly via the phase shifter 30, from where the automatic control device operates in the manner already described.

A further variant B of the device is shown in FIG. 3 and differs from the basic form described with reference to FIG Compensator 2 forms. The movement of the rotor 23 into the field of the stator 22 of the named variable capacitor 22, 23 again corresponds to the integral value A a of the gear wheel 15.

4 shows a further possible arrangement C which can be used in the case of an optically acting measuring element, for example. In this variant C , the measuring capacitor 1 consists of a radiation source 28 and a receiver 29 which is sensitive to electromagnetic waves and to which a further comparison receiver 24 is assigned. The latter is partially shielded by a variable diaphragm 25 which is moved by the gear wheel 15 via a toothed rack or the like, so that the degree of shielding forms a direct function of the aforementioned integral value Δ α .

Of course, not only light but also any other electromagnetic one can be used for this variant or radioactive radiation can be used.

Claims (1)

Patent claims: 1. A method for the automatic control of the delay of the slivers in drafting units or the like, in which one or more slivers are passed through an electrical measuring capacitor, the capacitance value of which changes with the weight per unit length of the tested section of the sliver or several slivers, whereupon this changes Changes in capacitance are converted into changes in a first electrical variable and used to form a second electrical variable as an electrical mean value of the first electrical variable, whereupon said second electrical variable is subtracted from said first electrical variable, so that a third electrical variable is obtained which now corresponds to the deviations of the weight of the section of the sliver or several slivers currently in the measuring capacitor from its mean value over a certain length, which is given by the duration of the formation of the mean value from the first electrical quantity , whereupon this third electrical variable regulates the angular speed of a drafting roller pair according to its magnitude and polarity after sufficient amplification, characterized in that the second electrical variable (LZ ₃ ) is continuously formed by the fact that from the speed (n ₃ ) of the drafting the sliver serving first drawing roller pair (5, 6) proportional first variable speed (W ₁₎ and from the second constant speed (n ₂₎ of the feed roller pair (7, 8) or by means of a differential gear (12). the like. a differential speed (m ₄ ) is formed, which then has the value zero when the speed (ra ₃ ) - of the drafting roller pair (5 ,. 6) has the value that corresponds to the desired average draft of the drafting system, whereupon this differential speed (w ₄ ) is reduced to a reduced rotational speed number (m ₅ ) is reduced, the shaft having this reduced speed (n ₅ ) in a time interval (i ₂ - ^ ₁ ) from a first angular position O ₁ to a second angular position a ₂ , the difference Aa of which is an integral value fe Δ α - 2 π J n ₅ · dt H which is formed from the differential speed curve integrated over a time interval At = t ₂ - U ₁ after time, whereupon the angle difference Ct ₂ -O ₁ representing the integral value Aa is converted into an electrical voltage change equivalent to it by means of a mechanical-electrical converter (16) is converted, which represents the second electrical quantity as an electrical signal (U ₃ ). 2. The method according to claim 1, characterized in that the second electrical variable (U ₃ ) is tapped from a tap (17) of a potentiometer acting as a mechanical-electrical converter (16) which is fed _{with a constant voltage (CZ 2), furthermore that the speed (M 4} ) output by the differential gear (12) is reduced so far that the entire range of rotation of the number of full revolutions determined by the size and length of the cross-sectional fluctuations to be regulated in the sliver or in several slivers (9) The cage (12 ') of the differential gear (12) is reduced to at most the range of rotation (a ₀ ) possible for the tap (17) of the potentiometer (16). 3. Device for carrying out the method according to claim 1, characterized by a differential gear (12) to which a variable, a speed (n _s ) of a drafting roller pair (5, 6) proportional speed (M ₁ ) and a constant speed (n ₂ ) of a pair of feed rollers (7, 8) is communicated and in which the differential _{speed (re 4} ) from the variable speed (M ₁ ) and the constant speed (n ₂ ) is formed, further by a reduction gear (14, 15) for reducing the differential speed (n _t ) to a speed (n _s ), further by a mechanical-electrical converter (16) controlled by the latter for generating an electrical signal (U _s ) as a second electrical variable that only follows very slowly changing changes in a first electrical variable. 4. Apparatus according to claim 3, characterized by a potentiometer as a mechanical-electrical Converter (16), at its terminals (18 and 19) a constant voltage (CZ _{2 ) is applied and its tap (17) decreases the partial voltage (CZ 3} ) corresponding to the angle (α) spanned between the terminal (19) and the tap (17) as a second electrical variable. 5. Apparatus according to claim 3, characterized by a variable capacitor (22, 23) as a mechanical-electrical converter for outputting an electrical signal (U ₃ ) as a second electrical variable, which is the relative immersion depth of the rotor (23) in the field of the stator (22) of the capacitor (22, 23) corresponds. 6. The device according to claim 3, characterized by an arrangement consisting of a source (28) of electromagnetic radiation and receivers (24 and 29) associated therewith, with part of the electromagnetic radiation on the way from its source (28) in place of the previous measuring capacitor to the receiver (29) the fiber band (9) to be measured penetrates and is thereby partially attenuated, and that a further part of the electromagnetic radiation passes through an aperture (25) on its way from the source (28) to the other receiver (24), the opening of which can be controlled by the reduced speed (n ₅ ) of the differential gear (12). 7. Apparatus according to claim 3 and one of claims 4 to 6, characterized by contactor (20 and 21) at the end positions of the moving part of the mechanical-electrical converter (16), whereby when these end positions (18 or 19) are reached by its movable tap (17) a circuit that triggers an alarm device is closed. 8. The device according to claim 3, characterized by an electrical measuring bridge (26) which by a mechanical-electrical converter (16) acting potentiometer in connection with the measuring capacitor (1) or the like. Is formed and by the position of the movable tap (17) of the mentioned potentiometer is adjusted. 9. Apparatus according to claim 3, characterized in that the differential gear (12) as Planetary gear is formed. 10. The device according to claim 3, characterized by a reduction gear (14, 15), whose reduction ratio can be changed. Considered publications:
French Patent No. 1 106 188. Legacy Patents Considered:
German Patent No. 1 043 886. 1 sheet of drawings © 009 698/77 1.61