Title:
PROCESS AND APPARATUS FOR DETERMINING THE ACTION OF AN ELECTRONIC THREAD CLEANER
United States Patent 3594558
Abstract:
The cleaning action of an electronic thread cleaner is determined by calculating from variations in time of the thickness of a thread at least one value determined by the appearance of frequent variations in thickness, the value being that of a suitably selected auxiliary quantity which can be determined in the range of frequent thickness variations as well as the range of rare thickness variations. Then the cleaning action can be determined on the basis of this value or values by extrapolation of the course of this auxiliary quantity depending upon the set parameters of the thread cleaner within the range of the rare deviations in thickness.
US Patent References:
Apparatus and method for testing drape of a fabric
Hamburger et al. - 1955 - 2714328
Apparatus and method for testing drape of a fabric
Hamburger et al. - 1955 - 2714328
Application Number:
04/792332
Publication Date:
07/20/1971
Filing Date:
01/21/1969
View Patent Images:
Export Citation:
Assignee:
Aktiengesellschaft Gebrueder Loepfe (Zurich, CH)
Primary Class:
Other Classes:
356/238.100, 28/227, 702/170
International Classes:
B65H63/06; G01N33/36; B65H63/00; G06G7/12
Field of Search:
235/184,185,151.3
Primary Examiner:
Botz, Eugene G.
Assistant Examiner:
Wise, Edward J.
Claims:
I claim
1. A process of determining the cleaning action of an electronic thread cleaner, which comprises producing at least one value of an auxiliary quantity from variations in thread thickness, said value being determined by the appearance of frequent thickness variations, whereby said auxiliary quantity is fixable in the range of frequent thickness variations as well as in the range of rare thickness variations, and extrapolating the course of said auxiliary quantity depending upon set parameters of the thread cleaner in the range of rare thickness deviations.
2. A process in accordance with claim 1, wherein an end value resulting from the observation of a very long thread length and consisting of the sum of values of an occurrence function, investigated in the thread cleaner when a thread thickness appears and related to the observed length, is selected for said auxiliary quantity.
3. A process in accordance with claim 1, wherein an end value resulting from the observation of a very long thread length and consisting of the sum of lengths produced in the course of a signal caused by variations in thread thickness when a set value is exceeded and related to the observed length, is selected for said auxiliary quantity.
4. A process in accordance with claim 3, comprising producing said signal by filtering during the course of thickness variations and using said signal for determining the length sections.
5. A process in accordance with claim 1, wherein an end value resulting from the observation of a very long thread length and consisting of the sum of deviations of the thread thickness from a reference value and related to the observed length, is selected for said auxiliary quantity.
6. An apparatus for determining the cleaning action of an electronic thread cleaner which comprises, a device for producing an auxiliary quantity, the value of said auxiliary quantity being determined by the appearance of frequent thickness variations, whereby said auxiliary quantity is fixable in the range of frequent thickness variations as well as in the range of rare thickness variations, an evaluating circuit of the thread cleaner, a device for producing actuating voltages for said evaluating circuit and maintaining the actuating voltages corresponding to a set value in a predetermined relationship, and means interconnecting said two devices.
7. An apparatus in accordance with claim 6, having a separately actuated device for producing actuating voltages for each set value.
8. An apparatus in accordance with claim 6, wherein the differences between different values of the actuating voltage have a constant ratio for a set value.
9. An apparatus in accordance with claim 6, wherein said device for producing said auxiliary quantity comprises an integrator and an accumulating condenser.
10. The apparatus for determining the cleaning action of an electronic thread cleaner, said electronic thread cleaner comprising means for sensing a running thread and producing an electrical output signal indicating the thickness of the thread, and severing means operatively connected in series with the output of said sensing means, said apparatus comprising:
11. The apparatus as defined in claim 10 which further comprises:
1. A process of determining the cleaning action of an electronic thread cleaner, which comprises producing at least one value of an auxiliary quantity from variations in thread thickness, said value being determined by the appearance of frequent thickness variations, whereby said auxiliary quantity is fixable in the range of frequent thickness variations as well as in the range of rare thickness variations, and extrapolating the course of said auxiliary quantity depending upon set parameters of the thread cleaner in the range of rare thickness deviations.
2. A process in accordance with claim 1, wherein an end value resulting from the observation of a very long thread length and consisting of the sum of values of an occurrence function, investigated in the thread cleaner when a thread thickness appears and related to the observed length, is selected for said auxiliary quantity.
3. A process in accordance with claim 1, wherein an end value resulting from the observation of a very long thread length and consisting of the sum of lengths produced in the course of a signal caused by variations in thread thickness when a set value is exceeded and related to the observed length, is selected for said auxiliary quantity.
4. A process in accordance with claim 3, comprising producing said signal by filtering during the course of thickness variations and using said signal for determining the length sections.
5. A process in accordance with claim 1, wherein an end value resulting from the observation of a very long thread length and consisting of the sum of deviations of the thread thickness from a reference value and related to the observed length, is selected for said auxiliary quantity.
6. An apparatus for determining the cleaning action of an electronic thread cleaner which comprises, a device for producing an auxiliary quantity, the value of said auxiliary quantity being determined by the appearance of frequent thickness variations, whereby said auxiliary quantity is fixable in the range of frequent thickness variations as well as in the range of rare thickness variations, an evaluating circuit of the thread cleaner, a device for producing actuating voltages for said evaluating circuit and maintaining the actuating voltages corresponding to a set value in a predetermined relationship, and means interconnecting said two devices.
7. An apparatus in accordance with claim 6, having a separately actuated device for producing actuating voltages for each set value.
8. An apparatus in accordance with claim 6, wherein the differences between different values of the actuating voltage have a constant ratio for a set value.
9. An apparatus in accordance with claim 6, wherein said device for producing said auxiliary quantity comprises an integrator and an accumulating condenser.
10. The apparatus for determining the cleaning action of an electronic thread cleaner, said electronic thread cleaner comprising means for sensing a running thread and producing an electrical output signal indicating the thickness of the thread, and severing means operatively connected in series with the output of said sensing means, said apparatus comprising:
11. The apparatus as defined in claim 10 which further comprises:
Description:
This invention relates to a process and an apparatus for determining the action of an electronic thread cleaner.
Electronic thread cleaners are used in textile thread winding machines for the supervision of the thickness of the moving thread. When the thread has a thickened section which in the course of the further treatment of the thread could cause the machine to stop or would detrimentally affect the appearance of the finished product, this thickened section is determined by the thread cleaner and is removed from the thread. In the course of this "cleaning operation" the disturbing errors in the thread are replaced by less disturbing thread knots.
The extent of the activating thread error is fixed by a setting of the thread cleaner. It depends in individual cases upon the type of the thread being used, its further treatment, its intended use, special requirements for the quality of the final product, etc.
In actual practice it is often difficult to find a setting which will result in the desired cleaning effect or to estimate the cleaning effect which will be produced by a specific setting.
Usually, approximately made settings are used for tryouts with spools and the number and type of errors thereby determined produce information as to the cleaning effect to be expected.
Errors in thread which must be corrected occur comparatively rarely, for example, in one spool location there may be on the average 1 to 2 errors for every 5 minutes or for a yarn length of 4,000 meters. Thus the setting of a thread cleaner on the basis of spool tryouts consumes a very large amount of time and is expensive. Therefore, the tendency is to predict information about settings which is not sufficiently statistically justified, with the danger that improper settings will be used producing economic and qualitative damages.
An object of the present invention is to eliminate these drawbacks by determining the cleaning effect corresponding to the specific setting of the thread cleaner in the simplest possible manner and within a short time.
Other objects of the present invention will become apparent in the course of the following specification.
In the accomplishment of the objectives of the present invention it was found advisable to calculate from time variations of the thickness of a thread at least one value determined by the appearance of frequent variations in thickness. This value is that of a selected auxiliary quantity which can be determined within the range of frequent thickness variations as well as the range of rare thickness variations. Then the cleaning effect can be determined from this value by extrapolation of the course of this auxiliary quantity depending upon the set parameters of the thread cleaner within the range of the rare deviations in thickness.
Preferably an end value is selected for this auxiliary quantity which results from observing a very long length of thread, the end value being that of the sums of values of a functional development investigated in a thread cleaner during the appearance of a thickening and related to the examined length of thread.
The invention will appear more clearly from the following detailed description when taken in connection with the accompanying drawings, showing, by way of example only, preferred embodiments of the inventive idea.
IN THE DRAWINGS:
FIG. 1 is a diagram illustrating the signals appearing in a thread cleaner as a function of time.
FIG. 2 is a block circuit diagram of a device for determining a value of the auxiliary quantity.
FIG. 3 is a diagram showing the course of the auxiliary quantity related to a specific course of a signal.
FIG. 4 is a block circuit diagram of a one parameter thread cleaner with a device for setting the desired extent of cleaning.
FIG. 5 is a block circuit diagram of a two parameter thread cleaner with a corresponding setting device.
In carrying out the present invention a signal is produced in the testing device of an electronic thread cleaner, the course in time of which corresponds to the course of the thread thickness along the thread. This signal f(t) is illustrated in FIG. 1. It contains the entire concerning the occurrences to be observed, namely, the thickened portions of the thread which, by way of example, are greater than a certain predetermined reference value p. A single event can be represented in different ways with the help of the function f(t). For that purpose a so-called event-function is derived generally from f(t). For example, the maximal thickness deviations d 1 , the thread lengths 1 i during which f(t) is greater than the reference value p, distances a 1 between two length sections which follow each other, or a function of such values can be all evaluated in the thread cleaner. Another possibility consists in changing initially the function f(t) itself, for example, and to evaluate the function thus produced in the manner described for f(t).
FIG. 2 illustrates diagrammatically a device of the present invention for evaluating the information concerning the thicknesses of the thread F.
A sensing head TK, which may be optical supplies this information in the form of the function f (t) containing the values which, as already stated, serve to evaluate an occurrence. The sum of these occurrences constitutes an amount M. In the evaluating section EE which contains thickness discriminating (Schmitt trigger) and length measuring circuits a part m of this amount is selected, representing occurrences which satisfy specific criteria. These criteria are fixed by the structure of the evaluating circuit and by the values (P k ) of the set values of the thread cleaner. The parameters p k are determined in the threshold-setting circuit ZE 2 of the central actuating device ZE by the setting E and are transmitted to the evaluating circuit, for example, as electrical actuating voltages. The evaluating circuit transmits information concerning the partial amount m to the integrating circuit (Miller integrator) ZE 1 of the actuating device ZE wherein the corresponding value of an auxiliary quantity W is derived therefrom.
The auxiliary quantity W is so selected that it is precisely defined for a specific occurrence value m. Since a specific partial value m of the total amount M is related to each parameter arrangement (p k ), namely, to each group of parameters p 1 , p 2 ,.... p k representing a setting of the thread cleaner, the auxiliary quantity W is a specific function of the setting of the thread cleaner.
The process of the present invention will be explained now on the basis of the following simple example:
It is assumed that the setting of the thread cleaner is given by a single parameter p which, as shown in FIG. 1, is represented as a step in the signal course f(t), or f(t). The occurrence value m can be also described, for example, as a single quantity, which in this case represents the occurrence function, for example, as the length sections 1 i (p) corresponding to the step p.
As auxiliary quantity W shall be considered as the end value of the sums of all 1 i related to the observed length L, the end value resulting from a very long length L according to the formula: L
fig. 3 shows the course of this quantity dependent upon the step p. The further is p removed from the course in time of the signal f(t), the rarer become the observed occurrences, namely, the transgression of the step p, and thus the smaller becomes the corresponding quantity W.
Let it be assumed that W(a)=A, W(b)=B and W(x)=X, whereby A and B should describe comparatively frequent occurrences and thus produce measurable quantities even for short thread lengths, while the step x is within the range of thickened portions which must be eliminated by the thread cleaning. The value x which corresponds to these rare occurrences, therefore, cannot be obtained within the observed lengths occurring in practice; it amounts to about 10 - 5 , while by comparison A is about 0.1 and B is about 0.005, so that they can be measured within comparatively short observation intervals.
It is important, as experience has shown, that the observed function W should have the same general continuity for a group of yarns in the range (a, x ). This corresponds, for example, in this case to a function of the type exp(-p n ), namely, particularly to the course of frequency closeness of a Gauss normal distribution. This means that the two measured values W(a)=A and W(b)=B which lie in the range of frequent occurrences, can be used by extrapolation for determining the value x of the set parameter p, which corresponds to a predetermined value x of the auxiliary quantity which represents the occurrence of rare yarn defects.
Similarly on the basis of W(a)=A and W(b)=B, it is possible to determine the corresponding value x of the auxiliary quantity from a given setting p=x. Thus this setting provides a measurement for the cleaning action of the thread cleaner.
FIG. 4 illustrates diagrammatically an apparatus by means of which this can be attained. TK indicates again the sensing head of the thread cleaner which produces the signal f(t). This signal is amplified in an amplifier V and is filtered in a low-pass filter circuit TP which produces the signal function f(t). In the following thickness discriminating circuit S 1 of the thread cleaner which contains a Schmitt-trigger, f(t) is compared with the set cleaning step x and a steering impulse for the yarn severing device TV is produced as soon as f(t) x.
To this apparatus which is known in prior art the present invention adds a device for determining the desired cleaning action. The device of the present invention includes a second thickness discriminating circuit S 2 which also receives the signal f(t) and which is connected on the other hand selectively with one of the contacts a or b of a voltage divider R 1 , R 2 . The voltage divider serves for producing actuating voltages which correspond to the steps p=a or p=b of FIG. 3. The values of the auxiliary quantity W which are thus produced are determined in integrating circuit W which follows the device S 2 , and are indicated in indicating device I.
The course of the auxiliary quantity W depending upon the set step P which is known from experience and which in this case, as already stated, corresponds to a normal distribution in the range under consideration, results in the equation(x-a)/(b-a)=k for two adopted values of the auxiliary quantity W(a)=A and W(b)=B for a desired cleaning action X, whereby k depends only upon the values A, B and X. This makes possible a simple extrapolation from the range of frequent occurrences to the range of rare occurrences by the use of voltage dividers in the following manner:
A predetermined value A is set in the indicating device I by means of the setting device E A , the switch being in the position A. Then it is switched over to the position B and the step b is determined by the setting device E B . The value B of the auxiliary quantity which is shown by the instrument, is thus a measure for the value x which corresponds to very long lengths of thread and thus to the cleaning action of the thread cleaner.
In the case under consideration, wherein the auxiliary quantity has the form
the integrating circuit W used for its determination is preferably constructed as a Miller integrator. The discriminator step S 2 consists then, for example, of a Schmitt-trigger which supplies a series of impulses of a given size and having a duration corresponding to the length sections l i . These impulses charge in the Miller integrator a integrator a charging condenser with constant current during the stretch l i . The leak current discharging the condenser has the effect that a stationary condition is produced in which the charge of the condenser constitutes a measure for the average number and the average size of the length sections l i . When the capacity is sufficiently large and the leak current is sufficiently small, the comparatively frequent impulses l i produce a condenser voltage which corresponds to the value W.
Another auxiliary quantity tested in practice consists of the formula
for a single parametric cleaning setting and an occurrence factor (d i ). This formula has an extrapolating development similar to one described above.
In general, occurrences considered during thread cleaning are described by more than one factor and supply several parameters for determining the setting of the cleaner.
By way of example, let the values l i and d i shown in FIG. 1, be considered as indicating a thread thickness, whereby the reference value p which defines them is considered to be fixed. An occurrence function formed by these indications is examined in the thread cleaner, for example, the function (l i /p l )+(d i /p 2 ), whereby p 1 and p 2 indicate the setting parameters. The occurrences of the partial amount m selected from M suffice to obtain the inequality
By analogy with the single parameter case the auxiliary quantity can be again obtained from the occurrence function, namely
As established in practice, this produces a function of the type exp (-p 1 2 -p 2 2 ), always in the range under consideration and at least for one group of yarns; it can be extrapolated into the range of rarely occurring events by the use of two setting values, each in the planes p 1 =const. and p 2 =const.
FIG. 5 is a block circuit diagram of a corresponding apparatus. The signal produced in the sensing head TK is supplied to two parallel channels L and D in which the values l i /p 1 and d i /p 2 are formed. Threshold-setting circuits p 1 and p 2 are used to determine the setting parameters. The outlets of the channels L, D are added in the addition circuit A and the occurrence function which is thus produced is transmitted in the switch position X 1 , X 2 to the discriminating circuit S which actuates the yarn-severing device TV. In the switch position A 1 , B 1 A 2 , B 2 the occurrence function is transmitted to a suitable integrating circuit W, which, for example, can again contain a Miller integrator, to produce the auxiliary quantity which is indicated in the indicating device I. If desired, a separate device L, D, A can be provided for operating the integrating circuit W. This makes possible simultaneous cleaning and indication. The determination of the two cleaning parameters p 1 =x 1 and p 2 =x 2 takes place separately by the setting of values A 1 , B 1 with P 1 and A 2 , B 2 with P 2 .
The various circuits and devices disclosed herein, excepting the two channels L and D of FIG. 5, are fully described and explained in both structure and operation in U.S. Pat. No. 3,303,698, to Erich Loepfe, granted Feb. 14, 1967.
In general, one, two or more set points are necessary for extrapolation in each parameter depending upon the extent of the application, the required precision and the selection of the auxiliary quantity.
Finally, it should be noted that in each case only those functions can be considered as auxiliary quantities which have a uniform course from the range of often occurring to the range of rarely occurring events in the individual parameters p j while holding constant the remaining parameters (p 1 ....p j -1 , p j +1 ......p k ).
By the use of such an auxiliary quantity, the course of which once becomes known from practical experience, for example, from a very long spool experimentation with different yarns, it becomes possible to reduce the cleaning operation of a thread cleaner to a measurable quantity. This eliminates an important unsafe factor in thread cleaning, reduces the costs of the process and greatly improves the quality of the obtained products.
Electronic thread cleaners are used in textile thread winding machines for the supervision of the thickness of the moving thread. When the thread has a thickened section which in the course of the further treatment of the thread could cause the machine to stop or would detrimentally affect the appearance of the finished product, this thickened section is determined by the thread cleaner and is removed from the thread. In the course of this "cleaning operation" the disturbing errors in the thread are replaced by less disturbing thread knots.
The extent of the activating thread error is fixed by a setting of the thread cleaner. It depends in individual cases upon the type of the thread being used, its further treatment, its intended use, special requirements for the quality of the final product, etc.
In actual practice it is often difficult to find a setting which will result in the desired cleaning effect or to estimate the cleaning effect which will be produced by a specific setting.
Usually, approximately made settings are used for tryouts with spools and the number and type of errors thereby determined produce information as to the cleaning effect to be expected.
Errors in thread which must be corrected occur comparatively rarely, for example, in one spool location there may be on the average 1 to 2 errors for every 5 minutes or for a yarn length of 4,000 meters. Thus the setting of a thread cleaner on the basis of spool tryouts consumes a very large amount of time and is expensive. Therefore, the tendency is to predict information about settings which is not sufficiently statistically justified, with the danger that improper settings will be used producing economic and qualitative damages.
An object of the present invention is to eliminate these drawbacks by determining the cleaning effect corresponding to the specific setting of the thread cleaner in the simplest possible manner and within a short time.
Other objects of the present invention will become apparent in the course of the following specification.
In the accomplishment of the objectives of the present invention it was found advisable to calculate from time variations of the thickness of a thread at least one value determined by the appearance of frequent variations in thickness. This value is that of a selected auxiliary quantity which can be determined within the range of frequent thickness variations as well as the range of rare thickness variations. Then the cleaning effect can be determined from this value by extrapolation of the course of this auxiliary quantity depending upon the set parameters of the thread cleaner within the range of the rare deviations in thickness.
Preferably an end value is selected for this auxiliary quantity which results from observing a very long length of thread, the end value being that of the sums of values of a functional development investigated in a thread cleaner during the appearance of a thickening and related to the examined length of thread.
The invention will appear more clearly from the following detailed description when taken in connection with the accompanying drawings, showing, by way of example only, preferred embodiments of the inventive idea.
IN THE DRAWINGS:
FIG. 1 is a diagram illustrating the signals appearing in a thread cleaner as a function of time.
FIG. 2 is a block circuit diagram of a device for determining a value of the auxiliary quantity.
FIG. 3 is a diagram showing the course of the auxiliary quantity related to a specific course of a signal.
FIG. 4 is a block circuit diagram of a one parameter thread cleaner with a device for setting the desired extent of cleaning.
FIG. 5 is a block circuit diagram of a two parameter thread cleaner with a corresponding setting device.
In carrying out the present invention a signal is produced in the testing device of an electronic thread cleaner, the course in time of which corresponds to the course of the thread thickness along the thread. This signal f(t) is illustrated in FIG. 1. It contains the entire concerning the occurrences to be observed, namely, the thickened portions of the thread which, by way of example, are greater than a certain predetermined reference value p. A single event can be represented in different ways with the help of the function f(t). For that purpose a so-called event-function is derived generally from f(t). For example, the maximal thickness deviations d 1 , the thread lengths 1 i during which f(t) is greater than the reference value p, distances a 1 between two length sections which follow each other, or a function of such values can be all evaluated in the thread cleaner. Another possibility consists in changing initially the function f(t) itself, for example, and to evaluate the function thus produced in the manner described for f(t).
FIG. 2 illustrates diagrammatically a device of the present invention for evaluating the information concerning the thicknesses of the thread F.
A sensing head TK, which may be optical supplies this information in the form of the function f (t) containing the values which, as already stated, serve to evaluate an occurrence. The sum of these occurrences constitutes an amount M. In the evaluating section EE which contains thickness discriminating (Schmitt trigger) and length measuring circuits a part m of this amount is selected, representing occurrences which satisfy specific criteria. These criteria are fixed by the structure of the evaluating circuit and by the values (P k ) of the set values of the thread cleaner. The parameters p k are determined in the threshold-setting circuit ZE 2 of the central actuating device ZE by the setting E and are transmitted to the evaluating circuit, for example, as electrical actuating voltages. The evaluating circuit transmits information concerning the partial amount m to the integrating circuit (Miller integrator) ZE 1 of the actuating device ZE wherein the corresponding value of an auxiliary quantity W is derived therefrom.
The auxiliary quantity W is so selected that it is precisely defined for a specific occurrence value m. Since a specific partial value m of the total amount M is related to each parameter arrangement (p k ), namely, to each group of parameters p 1 , p 2 ,.... p k representing a setting of the thread cleaner, the auxiliary quantity W is a specific function of the setting of the thread cleaner.
The process of the present invention will be explained now on the basis of the following simple example:
It is assumed that the setting of the thread cleaner is given by a single parameter p which, as shown in FIG. 1, is represented as a step in the signal course f(t), or f(t). The occurrence value m can be also described, for example, as a single quantity, which in this case represents the occurrence function, for example, as the length sections 1 i (p) corresponding to the step p.
As auxiliary quantity W shall be considered as the end value of the sums of all 1 i related to the observed length L, the end value resulting from a very long length L according to the formula: L
fig. 3 shows the course of this quantity dependent upon the step p. The further is p removed from the course in time of the signal f(t), the rarer become the observed occurrences, namely, the transgression of the step p, and thus the smaller becomes the corresponding quantity W.
Let it be assumed that W(a)=A, W(b)=B and W(x)=X, whereby A and B should describe comparatively frequent occurrences and thus produce measurable quantities even for short thread lengths, while the step x is within the range of thickened portions which must be eliminated by the thread cleaning. The value x which corresponds to these rare occurrences, therefore, cannot be obtained within the observed lengths occurring in practice; it amounts to about 10 - 5 , while by comparison A is about 0.1 and B is about 0.005, so that they can be measured within comparatively short observation intervals.
It is important, as experience has shown, that the observed function W should have the same general continuity for a group of yarns in the range (a, x ). This corresponds, for example, in this case to a function of the type exp(-p n ), namely, particularly to the course of frequency closeness of a Gauss normal distribution. This means that the two measured values W(a)=A and W(b)=B which lie in the range of frequent occurrences, can be used by extrapolation for determining the value x of the set parameter p, which corresponds to a predetermined value x of the auxiliary quantity which represents the occurrence of rare yarn defects.
Similarly on the basis of W(a)=A and W(b)=B, it is possible to determine the corresponding value x of the auxiliary quantity from a given setting p=x. Thus this setting provides a measurement for the cleaning action of the thread cleaner.
FIG. 4 illustrates diagrammatically an apparatus by means of which this can be attained. TK indicates again the sensing head of the thread cleaner which produces the signal f(t). This signal is amplified in an amplifier V and is filtered in a low-pass filter circuit TP which produces the signal function f(t). In the following thickness discriminating circuit S 1 of the thread cleaner which contains a Schmitt-trigger, f(t) is compared with the set cleaning step x and a steering impulse for the yarn severing device TV is produced as soon as f(t) x.
To this apparatus which is known in prior art the present invention adds a device for determining the desired cleaning action. The device of the present invention includes a second thickness discriminating circuit S 2 which also receives the signal f(t) and which is connected on the other hand selectively with one of the contacts a or b of a voltage divider R 1 , R 2 . The voltage divider serves for producing actuating voltages which correspond to the steps p=a or p=b of FIG. 3. The values of the auxiliary quantity W which are thus produced are determined in integrating circuit W which follows the device S 2 , and are indicated in indicating device I.
The course of the auxiliary quantity W depending upon the set step P which is known from experience and which in this case, as already stated, corresponds to a normal distribution in the range under consideration, results in the equation(x-a)/(b-a)=k for two adopted values of the auxiliary quantity W(a)=A and W(b)=B for a desired cleaning action X, whereby k depends only upon the values A, B and X. This makes possible a simple extrapolation from the range of frequent occurrences to the range of rare occurrences by the use of voltage dividers in the following manner:
A predetermined value A is set in the indicating device I by means of the setting device E A , the switch being in the position A. Then it is switched over to the position B and the step b is determined by the setting device E B . The value B of the auxiliary quantity which is shown by the instrument, is thus a measure for the value x which corresponds to very long lengths of thread and thus to the cleaning action of the thread cleaner.
In the case under consideration, wherein the auxiliary quantity has the form
the integrating circuit W used for its determination is preferably constructed as a Miller integrator. The discriminator step S 2 consists then, for example, of a Schmitt-trigger which supplies a series of impulses of a given size and having a duration corresponding to the length sections l i . These impulses charge in the Miller integrator a integrator a charging condenser with constant current during the stretch l i . The leak current discharging the condenser has the effect that a stationary condition is produced in which the charge of the condenser constitutes a measure for the average number and the average size of the length sections l i . When the capacity is sufficiently large and the leak current is sufficiently small, the comparatively frequent impulses l i produce a condenser voltage which corresponds to the value W.
Another auxiliary quantity tested in practice consists of the formula
for a single parametric cleaning setting and an occurrence factor (d i ). This formula has an extrapolating development similar to one described above.
In general, occurrences considered during thread cleaning are described by more than one factor and supply several parameters for determining the setting of the cleaner.
By way of example, let the values l i and d i shown in FIG. 1, be considered as indicating a thread thickness, whereby the reference value p which defines them is considered to be fixed. An occurrence function formed by these indications is examined in the thread cleaner, for example, the function (l i /p l )+(d i /p 2 ), whereby p 1 and p 2 indicate the setting parameters. The occurrences of the partial amount m selected from M suffice to obtain the inequality
By analogy with the single parameter case the auxiliary quantity can be again obtained from the occurrence function, namely
As established in practice, this produces a function of the type exp (-p 1 2 -p 2 2 ), always in the range under consideration and at least for one group of yarns; it can be extrapolated into the range of rarely occurring events by the use of two setting values, each in the planes p 1 =const. and p 2 =const.
FIG. 5 is a block circuit diagram of a corresponding apparatus. The signal produced in the sensing head TK is supplied to two parallel channels L and D in which the values l i /p 1 and d i /p 2 are formed. Threshold-setting circuits p 1 and p 2 are used to determine the setting parameters. The outlets of the channels L, D are added in the addition circuit A and the occurrence function which is thus produced is transmitted in the switch position X 1 , X 2 to the discriminating circuit S which actuates the yarn-severing device TV. In the switch position A 1 , B 1 A 2 , B 2 the occurrence function is transmitted to a suitable integrating circuit W, which, for example, can again contain a Miller integrator, to produce the auxiliary quantity which is indicated in the indicating device I. If desired, a separate device L, D, A can be provided for operating the integrating circuit W. This makes possible simultaneous cleaning and indication. The determination of the two cleaning parameters p 1 =x 1 and p 2 =x 2 takes place separately by the setting of values A 1 , B 1 with P 1 and A 2 , B 2 with P 2 .
The various circuits and devices disclosed herein, excepting the two channels L and D of FIG. 5, are fully described and explained in both structure and operation in U.S. Pat. No. 3,303,698, to Erich Loepfe, granted Feb. 14, 1967.
In general, one, two or more set points are necessary for extrapolation in each parameter depending upon the extent of the application, the required precision and the selection of the auxiliary quantity.
Finally, it should be noted that in each case only those functions can be considered as auxiliary quantities which have a uniform course from the range of often occurring to the range of rarely occurring events in the individual parameters p j while holding constant the remaining parameters (p 1 ....p j -1 , p j +1 ......p k ).
By the use of such an auxiliary quantity, the course of which once becomes known from practical experience, for example, from a very long spool experimentation with different yarns, it becomes possible to reduce the cleaning operation of a thread cleaner to a measurable quantity. This eliminates an important unsafe factor in thread cleaning, reduces the costs of the process and greatly improves the quality of the obtained products.