EP0943575B1 - Method for monitoring waxing of a moving yarn - Google Patents

Description

The invention relates to a method according to the Preamble of the first claim.

For the yarn processing it may be necessary to use the coefficient of friction of the yarn. A known method for this is Waxing. Through paraffin particles applied to the yarn the running and sliding properties, especially when Knit and knit, much improved. The paraffin application e.g. on winding machines during the rewinding of the yarn from cops to packages. The thread with a Paraffin body brought into contact through the Paraffin removal consumed.

Is a paraffin body used up or its contact with the Thread interrupted and if this is not recognized, it can non-waxed yarn in the subsequent processing Broken yarn or even needle breaks on a knitting machine cause, resulting in production errors or loss of production leads. Therefore, there are already different processes and Devices have been proposed to monitor the Allow waxing of the yarn.

Most procedures rely on the paraffin body is monitored itself and its observed use is signaled. The disadvantage here is that the contact of the Paraffin body with the thread can also be interrupted without that the paraffin body is used up, but only jammed or is dirty.

DE 195 47 870 A1 describes a method and a Device described, with the result of paraffin refining can be checked. For this purpose, the thread run is in front of and behind the Paraffinizer heat sensors arranged by the running thread with sliding friction. Any over frictional heat increase going beyond a certain value interpreted as a defect in the waxing device, which led to Switching off the winding unit concerned leads.

For the known method and the known device additional sensors are required, the use of which usually a winder is not provided. The signal processing must therefore be matched to these sensors.

The object of the present invention is to monitor the Paraffin application on a running thread with funds perform that already while monitoring the ongoing Winding operation can be used.

The task is solved with the help of the characteristic Features of the first claim. Advantageous embodiments of the Processes are claimed in the dependent claims.

Run friction drum and spool with the same Angular velocity or the angular velocities in a defined ratio causing strong images, e.g. 1: 1.5, to each other, the yarn layers are on top of each other stored. The reversal points are also one above the other. The leads to unwanted bulges on the surface the coil, the so-called image windings. By changing Slip between the friction drum and the spool can build up Image windings can be effectively reduced. A changing slip can by accelerating the friction drum at intervals be generated. If the drive power remains unchanged the slip with increasing coil diameter and thus increasing coil mass. But only if the Offset on the surface of the package in successive acceleration phases of the cheese changes noticeably, according to the invention, a failure of the Paraffin order closed.

The spool is driven by friction through the Friction drum. When accelerating the friction drum remains the coil in its peripheral speed more due to slippage or less behind the peripheral speed of the Friction drum back. With the help of this slip the Image disturbance. The friction force and thus that Drive torque on the coil depend on the winding technology parameters such as overlay compensation, yarn type, Bobbin mass, yarn preparation, etc.

On the friction drum as well as on the package holder sensors are attached in the coil frame with which the Angle of rotation and thus the angular velocity or Orbital period of the two rotating bodies is constantly determined become. This is usually used to determine what is going on the bobbin travel constantly changing diameter of the cheese. These sensors are also within the scope of the invention for Monitoring of the paraffin application used. The goes Invention based on the knowledge that if the Paraffinization of the surface of the surface by the traversing stroke Bobbin overlapping thread after a short time the friction behavior of the package surface significantly changed.

If paraffin waxing stops during a coil trip, is without further the change in the friction behavior of the Coil surface recognizable. However, since the friction behavior of the bobbin surface formed from paraffin thread Dependency on the winding spool, the lot and the Winding parameters is usually known, but at the latest, if the game runs for a while, it is also possible to post a package change to recognize that the friction behavior the package surface is outside of expected values.

To avoid a longer, non-paraffinated Thread section running onto the package is according to the invention provided the winding unit immediately after the failure of the To stop the paraffin application. However, it would be too possible but associated with losses when the cheese fully wound and then as an off-standard spool is discarded.

It also makes sense to stop the winding unit Send signal by which the operator is called. The operator can then do the appropriate Take action to get a proper wax application restore.

Should regarding the further processing of the on the package wound thread there is the requirement that even short Thread sections without paraffin should be avoided after the stopping of the winding unit the non-paraffinated Thread section by means of the suction nozzle from the one turned backwards Cheese or by hand.

A very important measure for determining the friction behavior the surface of the package on the friction drum is the absolute size of the slip between the friction drum and Coil that is in the acceleration phases during image disturbance occurs. This can be determined by evaluating the Angular velocities and orbital periods of the Determine the friction drum and the package. However, this To determine slip is the coil diameter, which is constantly changes during the bobbin trip, as in known ones and to calculate in the manner already mentioned above. This Calculation cannot during the acceleration phases be carried out during this time due to slip falsified diameter would be determined. For this reason the diameter of the coil in the acceleration-free Discontinued phases calculated and the course of the increase in Coil diameter on the basis of the previous Pre-calculated values for the acceleration phases. From the Difference between those adulterated by slip Coil diameter and the actual value of the The size of the slip in the coil diameter Determine slip phases quantitatively.

Then falls in successive acceleration phases unchanged drive power of the friction drum of the slip and stays at a lower level, that's it according to the invention a signal that no paraffin application the yarn is done. The coefficient of friction of the yarn and thus the Friction increased. This increase is so clear noticeable that the assignment to the paraffin application without further ado is possible.

In addition, the by means of the friction drum on the Friction force determined in the coil of the transmitted drive torque in Including the assessment, the statements on Friction behavior of the surface of the package even more clearly to meet. This will be done in the non-slip phase of the two Rotation body in the context of the image disturbance its delay friction, inertia and convection losses are determined as well as stress elements, the latter caused e.g. through the Thread tensile force of the running thread, determinable. These are but also in the acceleration phases. In this way parameters can be eliminated that have no relation to the Friction behavior of the surface of the package on the Friction drum stand. This will prevent the Paraffin application even faster and more clearly visible. In front it is also possible for everything, even at the beginning of the Coil travel the position of the function of the friction force in Dependence on slip clearly according to the criteria Differentiate paraffin application / no paraffin application.

If a thread tension sensor is available at the winding unit, alternatively, its output values, which are the load moment for form the two rotating bodies, included in the evaluation become. This at least prevents fluctuations in the Thread pull falsify the result of the slip determination.

By determining the storage offset, not only the absolute slip size included in the evaluation, but also the result of the hatching, causing the hatching process including the duration of the hatching. The Inclusion of this additional dimension also leads to significant differences, here in the function of the Storage offset depending on the slip, compared to the isolated Consideration of hatching.

An improvement in the informative value with regard to the Paraffin application can also be achieved in that a Reference value by averaging the friction behavior of the Cross-wound bobbins at several winding positions is determined, one of which certain degree of a deviation as the absence of Paraffin order is defined.

The invention will be further elucidated on the basis of exemplary embodiments explained.

Fig. 1

eine Spulvorrichtung mit einer Auswerteeinrichtung zur Bestimmung des Schlupfes,

Fig. 2

in einem Blockdiagramm den Aufbau einer Auswerteeinrichtung,

Fig. 3

ein Diagramm als einen kleinen Ausschnitt aus einer Spulreise zur Erläuterung der vorliegenden Erfindung,

Fig. 4

ein Diagramm über den zwischen einer Friktionstrommel und einer Spule auftretenden Schlupf während des Ausschnittes der Spulreise nach Fig. 3, wobei der Schlupf auf den Durchmesser der Spule skaliert ist,

Fig. 5

den Durchmesserverlauf in einem Beschleunigungs-Auslaufdiagramm einer konischen Spule,

Fig. 6

einen egalisierten Auslaufvorgang einer konischen Spule,

Fig. 7

ein Diagramm, in dem der relative Ablageversatz über den Schlupf aufgetragen ist, jeweils für ein paraffiniertes und ein nichtparaffiniertes Garn, und

Fig. 8

ein Diagramm, in dem die Friktionskraft über den Schlupf aufgetragen ist, jeweils für ein paraffiniertes und ein nichtparaffiniertes Garn.

Show it:

Fig. 1

a winding device with an evaluation device for determining the slip,

Fig. 2

in a block diagram the structure of an evaluation device,

Fig. 3

2 shows a diagram as a small section from a winding trip to explain the present invention,

Fig. 4

3 shows a diagram of the slip occurring between a friction drum and a coil during the cutting out of the winding trip according to FIG. 3, the slip being scaled to the diameter of the coil,

Fig. 5

the diameter curve in an acceleration run-out diagram of a conical coil,

Fig. 6

an equalized run-out process of a conical coil,

Fig. 7

a diagram in which the relative offset is plotted over the slip, in each case for a waxed and a non-waxed yarn, and

Fig. 8

a diagram in which the frictional force is plotted against the slip, for a paraffinated and a non-waxed yarn.

The winding device shown only schematically in Fig. 1, in particular the winding device of a winding unit Winding machine, has a friction drum 10, which means a drive motor 11 is driven. The friction drum 10 is provided with a reverse thread groove 12 so that it at the same time as a traversing device for an in Arrow direction via a thread tension sensor 13 by a Thread eyelet 14 serves thread 15. The thread 15 is on a coil sleeve 16 wound as a coil in a wild winding, so that a so-called cheese 17 is formed. Since the invention both in the manufacture of cylindrical packages and in Making tapered packages is applicable in Fig. 1 a cylindrical cheese 17 and in Fig. 2 a conical Cross-wound bobbin 17 'shown. If in the following one Spool radius or spool diameter is spoken at a conical cheese 17 'the neutral diameter or so-called driving diameters meant. The coil sleeve 16 is held by means of two coil plates 18, 19, each with a cone 20, 21 non-positively in the open ends of the sleeve 16 intervene. The bobbin 18, 19 with the sleeve 16 and thus rotating with the coil 17 are not in one Shown coil frame mounted, the one to the shaft 22nd the friction drum 10 parallel axis is pivotable.

The shaft 22 of the friction drum 10 is a sensor 23 assigned, which is designed, for example, as an angle encoder is. The angular velocity, Period or speed of the friction drum detected. the Coil plate 18 is assigned a sensor 24, which is also a a rotary encoder is formed. By means of this sensor the corresponding measured values of the coil 17 are determined. The Signals from sensors 23 and 24 are in a control and Evaluation device 25 detected.

In order to avoid image windings when manufacturing the coil 17, a so-called image disturbance is carried out, in which intermittent slip between the friction drum 10 and the Coil 17 is generated. This happens because the Drive motor 11 of the friction drum 10 alternately on and is turned off. If the speed falls below the Friction drum 10 after the drive motor 11 is switched off a predetermined value, the drive motor 11 is again turned on, causing the friction drum 10 up to a Maximum speed is accelerated. Then the drive motor 11 switched off again, whereupon the game is repeated. Due to the inertia of the coil occurs during the Acceleration of the friction drum 10 a slip between the Friction drum 10 and the cylindrical coil 17th

Starting from the initially empty on the friction drum 10 overlying bobbin tube 16, the radius or Diameter of the bobbin 17 due to the wound thread 15 until the coil 17 reaches its maximum radius or diameter has reached.

ω_sp Winkelgeschwindigkeit der Spule

ω_fw Winkelgeschwindigkeit der Friktionstrommel

r_sp Radius der Spule

r_fw Radius der Friktionstrommel.

Wird diese Berechnung in kurzen Zeitabständen laufend durchgeführt, beispielsweise in Zeitabständen von 0,1s, so ergibt sich eine Kurve, wie sie in Fig. 3 als Durchmesser (2 x r_sp) über der Zeit dargestellt ist.The coil radius r _sp can be calculated on the basis of the signals from the sensors 23, 24 using the following formula: ω sp × r sp = ω fw × r fw and from it r sp = (ω fw × r fw ) / ω sp , in it mean:

ω _sp angular velocity of the coil

ω _fw angular velocity of the friction _drum

r _sp radius of the coil

r _fw radius of the friction _drum .

If this calculation is carried out continuously at short time intervals, for example at time intervals of 0.1 s, a curve is produced as shown in FIG. 3 as a diameter (2 × r _sp ) over time.

3 shows an increase in diameter of approximately 0.75 mm in the range of a coil diameter of approximately 155.15 to approximately 155.9 mm in a period of approximately 17 seconds. The lower sections 30 of this curve correspond to the run-down phases in which the drive motor 11 of the friction drum 10 is switched off, so that the friction drum 10 and the coil 17 run without slippage in the case of a cylindrical coil geometry. The mentioned formula can therefore be used in these phase-out phases 30, so that the course of the curve shown in the phase-out phases 30 corresponds to the actual course of the increase in the coil radius r _sp or here the coil diameter. In the acceleration phases 31 lying between the run-down phases 30, the coil 17 has a lower peripheral speed than the friction drum 10. The calculation of the coil radius r _sp or the coil diameter using the formula mentioned there leads to a fictitious coil diameter or coil radius which is falsified by the slip that occurs , Due to the slip, an increase in the coil radius or coil diameter is calculated using the above formula, which is greater than the actual course of the increase in the coil diameter in the acceleration phase 31. The following applies to the winding speed: ν _sp = (1-S) × ν _tr . S stands for slip.

The drum speed ν _tr and the bobbin radius r _{sp can be} specified as known variables in the winding process. Therefore: ω sp xr sp = (1-S) x ν tr or S = 1 - (ω sp × r sp ) / ν tr and thus S = [ν tr - (ω sp × r sp )] / ν tr With ν tr = ω sp | s = o × r sp applies: S = [(ω sp | s = o × r sp ) - (ω sp × r sp )] / (ω sp | s = o × r sp ) It follows: S = 1 - (ω sp / ω sp | s = o )

The coil radius is calculated in the acceleration phases as the so-called falsified coil radius: r sp | r avail. = r sp × (ω sp | s = o / ω sp ) ω _sp | _{s = o} means: Under the condition that the slip = 0.

The following relationship results for the slip between drum and spool: S = (r sp | r avail. - r sp ) / r sp | r avail. Taking into account the course of the increase in the coil radius or coil diameter in one or more preceding phase-out phases 30 calculated from the measured values, the (actual) course of the increase in the coil radius or coil diameter for the subsequent acceleration phase can be calculated in advance in the form of a time-variant compensation line 32. The difference between the coil radius or diameter in the acceleration phases 31 calculated (falsified) from the signals from the sensors 23, 24 and the predicted course of the increase in the coil diameter according to the compensation lines 32 in the acceleration phases 31 is a measure of the actual occurrence in the acceleration phases 31 slip. In Fig. 4 this slip is plotted in percent over time on the diameter of the coil 17.

In the case of conical packages, the driven one changes Diameter at which the peripheral speeds of Friction drum and cheese coincide, fictitious at one Acceleration, as can be seen from Fig. 5. There is a fictitious increase in diameter 40. From this point in time 41 occurs an exclusively slip-prone drive. The during the Acceleration phase (diameter increase 40) calculated Coil diameter is adulterated and is during phase 42 of the drive with slip is approximately constant. To Switching off the friction drum reaches the fictitious Coil diameter the coil at point 43 again, and a real, driven diameter moves, proportional to the falling Speed of the friction drum, on the spool of the big one Towards the small diameter. This is the so-called Run-out phase 44. Towards the end of the run-in phase 44 the driven diameter due to the acceleration-free Drive a so-called neutral diameter zone in which each reached diameter of the conical cheese is definable.

Reaching the neutral zone is one of several Influencing factors dependent, for example on the flexing work Conicity of the coil and the friction between drum and coil, which interferes with the diameter determination. The The course of the curve shows an entry or Transient. For a diameter determination of the package the transient process cannot be used because here the falsified diameter with the neutral coil diameter, does not match. As for the next one Acceleration phase in the short term an actual Coil diameter must be present, this transient must be equalized. This is done by introducing Prior knowledge of the course of entry into the neutral zone. going one assumes that the above do not change the influencing factors mentioned, then it can be assumed that the previous disturbance cycles have a similar course like the current one. With this knowledge it is possible to find one To create a model of the current running-in behavior. is found this model course can predict the neutral cone diameter at all times during the running-in phase be calculated.

The calculation of a model can be used Compensation polynomial of nth degree. Are the model parameters (Polynomial coefficients) of the last n run-in cycles, see above can model a model simultaneously with the current running-in phase Run-in phase can be determined. For this, the n parameter sets of the running-in cycles averaged and a simultaneous course created become. If you divide the measured adulterated Diameter value with the corresponding model diameter value, see above you get an equalized diameter curve. This course is the amount of the currently valid cone diameter corrected.

The integration of several run-out cycles in the model run-out is recommended since it can be assumed that this will occur Differences between different expiry cycles are averaged. This method is shown in Fig. 6. Because of the outlets (n-2) and (n-1) will be a model outlet for the outlet (n) calculated and carried simultaneously. At the same time, the captured falsified diameter course through the Divided model diameter course, which equalized Diameter course in the phase-out phase results.

The time-variant compensation line 32 and the slip can be calculated, for example, in accordance with an evaluation device explained in FIG. 2. The period _durations measured by the sensors 23, 24 and thus also the angular velocity of the coil ω _sp and the friction _drum ω _fw are entered into a quotient _generator 33. Since the radius r _{fw of} the friction _drum 10 is constant, the quotient ω _fw to ω _sp is already representative of the coil radius r _sp , so that multiplication by the radius r _{fw of} the friction _drum 10 can be dispensed with. However, this value cannot yet be used for slip determination, since it is dependent on the diameter. This value is therefore entered into a linear filter 34, for example a Kaiman filter, to which the angular velocity ω _{sp of} the coil 17 'or 17 in FIG. 1 and the angular velocity ω _{fw of} the friction _drum 10 are also input. The diameter values or, in the case of the conical cheese, the calculated equalized curve are only made available to the filter in the phase-out phases of the image disturbance. This linear filter 34 forms the time-variant compensating line 32. The compensation radii are calculated in the slip-free phases. In the acceleration phases, the best-fit line is continued on the basis of its predetermined slope. This compensation line 32 is input together with the signal of the quotient 33 into a subtraction device 35, which then specifies the speed-independent and diameter-independent slip, ie the slip which is independent of the winding process state.

The slip s determined in this way forms the calculation basis for the storage offset, which is independent of the diameter. The following applies to the speed of the coil: v _coil (t) = (1 - s (t)) × v _drum (t).

wobei t₂ - t₁ die zu untersuchende Zeitspanne darstellt. Im Falle diskretisierter Schlupf- und Geschwindigkeitsverläufe gilt mit Δt als Abtastzeit:

The difference on the surface of the coil caused by the slip is calculated

where t ₂ - t _{1 represents} the time period to be examined. In the case of discretized slip and speed profiles, the following applies with Δt:

The size Δl is the storage offset. From this, it is possible to formulate a statement about the yarn laying on the bobbin surface with the aid of the length of a double stroke on the bobbin surface. This length is drum-specific and is calculated as 1 _drum = 2 × gg × 2 × π × r _drum , with gg as the number of drum turns (number of drum revolutions for a depositing stroke on the spool surface). If the offset is based on a double stroke, the relative offset results in percent. Δ = (Δl / l _drum ) × 100% and thus:

Since no other manipulation mechanisms for the Only the acceleration can be offset the friction drum the one required for the image disturbance Slip and thus create the offset. Assuming that Drive torque with every fault cycle regardless of Engine operating point is always the same, gives the size of the offset information about the size of the just prevailing slip.

Are during a coil trip after each disturbance cycle, that is a succession of acceleration of the coil and its drive-free runout, the values for the slip and the offset Entered as a point in a diagram creates narrowly limited ones Point clouds, their location and orientation provide information about the Quality of the respective disturbance cycle and thus of the slip result. The state of the interference cycles is shown. As the diameter of the coil increases, so does the Point cloud.

Because a waxed yarn has different friction properties than a non-waxed one, this is when winding it Yarn slip occurs differently and consequently also Filing offset. This is clearly shown in that shown in FIG. 7 Slip stock offset diagram can be seen. A point cloud that during a bobbin trip of a non-waxed yarn was recorded differs in location, Extent and course of a point cloud, the recorded during the bobbin trip of a waxed yarn has been. The prerequisite for this comparison is that, in addition to the Preparation the setting parameters during the two Coil trips are the same.

The absolute position of the point cloud can be over the entire machine or batch, that is, between many individual units become. This will cause discrepancies that are due to waning or point out the missing paraffin application, even faster and better recognized.

There were cylindrical bobbins made of the same yarn number wound at the same winding speeds. It was a medium one Edition compensation set and there was a Thread tension of 30 cN. The point cloud of the non-paraffinated Yarn extends in an area with little offset and slip, about up to 3.5% relative offset at 1.5% Slip, while the point cloud of the paraffinized yarn, clearly separated from the previous cloud, by about 4% relative offset and 1.5% slip to over 8% relative Storage offset and extends over 2.5% slip. A slip offset diagram allows the paraffin and the non-waxed condition of a yarn simply by its location clearly distinguish the slip offset points.

Slip and friction force are also proportionally related. A drop in the slip can therefore be determined via the course of the friction force. The friction force can be calculated from the drive torque acting on the coil. The drive torque acts on the coil during the acceleration phase of the image disturbance: m Kitchen sink = m friction - m loss - m burden ,

_Spule × J_Spule. Im Bereich der Auslaufphase von Trommel und Spule ist das Friktionsmoment m_Reib = 0 und die Spulendrehzahl reduziert sich aufgrund der Verlust- und Belastungsmomente, die auf das System wirken. Da in dieser Phase das System ohne weitere äußere Einflüsse ist, können diese Momente über die Winkelgeschwindigkeitsverläufe errechnet werden. Eine Entkopplung der Momentenbestimmung zwischen den Rotationskörpern Spule und Trommel wird über die Berechnung der korrespondierenden Leistungen durchgeführt. So gilt für die im Auslauf der Bildstörung erfaßte Verlust- und Belastungsleistung: pVerlust,Belastung = mV,B|Trommel × ωTrommel + mV,B|Spule × ωSpule Während es keine Möglichkeit gibt, mit den gegebenen Meßmitteln die Verlustleistung des Trommel-Spulensystems zu messen, kann die Summe der Antriebsverlustleistung und der fadenzugkraftbedingten Belastungsleistung explizit bestimmt werden.This moment causes the speed of the spool to increase within a certain time interval. The following applies: m _coil =

_Coil × J _coil . In the area of the phase-out phase of the drum and spool, the friction torque m _friction = 0 and the spool speed is reduced due to the loss and loading moments that act on the system. Since the system is without further external influences in this phase, these moments can be calculated using the angular velocity curves. The torque determination between the spool and drum rotating bodies is decoupled by calculating the corresponding power. The following applies to the loss and load power recorded at the end of the image disturbance: p Loss, stress = m V, B | drum × ω drum + m V, B | coil × ω Kitchen sink While there is no possibility to measure the power loss of the drum-coil system with the given measuring means, the sum of the power loss power and the thread tension-related load power can be determined explicitly.

The determination of the friction and convection losses of the drum drive can be carried out using run-out curves. Since the winding speed and thus the drum angular speed only varies by the set image interference stroke during winding operation (for example between ± 1.5% to ± 6%), the determination of this power loss only makes sense in this working area. For this reason, a model approach can be chosen that takes the outlet slope of the drum speed into account in the area of the production speed. The following therefore applies: m V | drum = - J drum × (Δω drum / .DELTA.t | working ). J _drum is the sluggishness of the drum

The measurement of the slope Δω _drum / Δt can be carried out during normal production without any significant loss of production. After each winding process interruption, the drum drive need only be decoupled from the bobbin for a very short period of time (lifting of the cheese) and switched off. After the initial slope has been measured, the drum drive can be actively braked to avoid unnecessary loss of production. Since this loss moment is constant during a bobbin trip, the runout measurements need only be carried out after each process-related interruption of the bobbin operation.

der beschleunigungsfreien Phasen : pAntrieb = mTrommel × ωTrommel + mSpule × ωSpule + pV,B. Wird diese Leistung auf das zugehörige Moment des Trommelantriebs bezogen, gilt: m_{Antrieb|Spule} = p_Antrieb / ω_Trommel. Die Bestimmung des über die Reibkraft erzeugten Friktionsmoments geht von der Gleichung für die Gesamtantriebsleistung aus. Die in dieser Gleichung aufgeführten Leistungen werden jedoch nicht alle über die Friktion aufgebracht. So hat die reine Trommelantriebsleistung, die reine Leistung, um die Trommel zu bewegen, keinen Einfluß auf die Kreuzspule. Ebenso sind die Antriebsverluste der Trommel für das Friktionsmoment ohne Bedeutung. Nach Umformen dieser Gleichung ergibt sich für die Friktions- oder Reibleistung: pReib = mSpule × ωSpule + pV,B. Hierbei berechnet sich das Friktionsmoment, bezogen auf die Kreuzspule, zu: mReib|Spule = pFriktion / ωSpule. The drive power is determined via the measured acceleration torques of the drum and spool. For the calculation of the total drive power, the equation is obtained

the acceleration-free phases: p drive = m drum × ω drum + m Kitchen sink × ω Kitchen sink + p V, B , If this power is related to the associated torque of the drum _drive , the following applies: m _{drive | coil} = p _drive / ω _drum . The determination of the friction torque generated via the friction force is based on the equation for the total drive power. However, the performances listed in this equation are not all applied through friction. So the pure drum drive power, the pure power to move the drum, has no influence on the package. The drive losses of the drum are also irrelevant for the frictional moment. After transforming this equation, the following results for friction or friction: p friction = m Kitchen sink × ω Kitchen sink + p V, B , Here, the friction torque, based on the package, is calculated as: m Friction | coil = p friction / ω Kitchen sink ,

The friction slip creates during the acceleration phase the image disturbance taking into account the friction parameters of the Drum-coil system the friction force and thus that Drive torque on the coil. It is a direct dependency of the winding technology parameters such as support compensation, Yarn type, bobbin mass, yarn preparation, etc. can be seen.

Are the working points of the slip measured during the coil travel and calculated using the equation v _coil (t) = (1-s (t)) × v _drum (t) or the equation m _{friction | coil} = p _friction / ω _coil , and those using the Equation for the calculation of the friction torque of the working points of the friction force, drawn in a diagram f _friction = f (s), results in a point cloud. 8, the point clouds from two coil trips are plotted. Two conical coils were wound. Except for the thread preparation, all setting parameters were the same, i.e. the same thread number, Nm 24, the same winding speed and the same image disturbance of 6%. A medium run compensation was set. The point clouds show a linear dependency between the friction force and the slip. This dependency can be approximated using a straight line. The behavior of a point cloud during the winding process can be represented using the two parameters of the straight line equation.

To more precisely localize the radio cloud characteristics and so that it can make the process properties possible with this representation the focus and the scatter to determine and use the point cloud. 8 is the influence of the paraffin application can be clearly seen. Without one Having to localize the point cloud alone can about the slope of the point cloud in the slip-friction force diagram the quality of the paraffin application be determined. The slope of the point cloud of the non-waxed yarn is 4.2 N /%, that of waxed yarn 0.63 N /%. The method according to the invention Monitoring the paraffin application can be very safe be considered as the preparation of the yarn, the Paraffin application, direct influence on the coefficient of friction µ des Exerts friction drive.

If a thread tension sensor 13 is present at the winding point, can these have a connection to the evaluation device 25, so that changes in thread tension in slip detection can be taken into account. This will make one of the most important influencing factors that have no relation to the coefficient of friction the cheese have eliminated.

Claims (9)

1. Method for monitoring the application of paraffin to a travelling yarn (15) at a winding station of a textile machine producing cross-wound bobbins (17), at which textile machine the cross-wound bobbin is driven at its periphery by a friction drum (10), the drive of the friction drum being switched on and off at intervals to avoid pattern windings in such a way that acceleration phases (31) with slippage between the friction drum and bobbin and slippage-free run-out phases (30) follow one another, characterised in that the friction behaviour of the surface of the cross-wound bobbin (17) on the friction drum (10) is monitored during bobbin travel, in that for this purpose values proportional to the coefficient of friction are determined and evaluated by continuous detection of the angular velocities (Wsp, Wfw) of the friction drum and the cross-wound bobbin, in that these values are compared with the expected course over the bobbin travel and in that significant deviations from this course are evaluated as a loss of the application of paraffin.
2. Method according to claim 1, characterised in that the winding station is stopped when a loss of the application of paraffin is determined.
3. Method according to claim 2, characterised in that in addition, a signal is generated to call the operator.
4. Method according to any one of claims 1 to 3, characterised in that the slippage between the cross-wound bobbin (17) and friction drum (10) is determined and evaluated as the value proportional to the coefficient of friction.
5. Method according to claim 4, characterised in that the frictional force is determined by the driving torque transmitted by the friction drum (10) to the bobbin (17), the frictional force being detected as a function of the slippage and used for evaluating the frictional behaviour of the surface of the cross-wound bobbin.
6. Method according to claim 5, characterised in that loss moments and load moments acting on the drive system friction drum (10)/cross-wound bobbin (17) are measured during the slippage-free run-out phases and taken into account in the determination of the frictional force.
7. Method according to claim 4, characterised in that the tensile force of the yarn is measured and the slippage value corrected during bobbin travel by changes in the tensile force of the yarn.
8. Method according to claim 4, characterised in that the depositing offset corresponding to a displacement of a reversal point for yarn deposit on a peripheral line of the bobbin (17) relative to the previous reversal point, is determined as a function of the slippage and is used for evaluating the frictional behaviour of the surface of the cross-wound bobbin on the friction drum (10).
9. Method according to any one of claims 1 to 8, characterised in that the frictional behaviour of the surface of the cross-wound bobbins (17) on the friction drum (10) is averaged at a predeterminable number of winding stations of the winding machine and is used as the basis of comparison for the frictional behaviour at each individual winding station.

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