DE19960285A1 - Monitor to register the increasing bobbin diameter during winding at a bobbin winder has a light transmitter and detector to register the gaps between the sensor and the bobbin and spindle surfaces - Google Patents

Abstract

To determine the diameter (D) of a bobbin (1) at a winder, during bobbin winding, the gaps are measured between the sensor (4) and the bobbin surface and the spindle surface. The bobbin diameter (D) is established by the difference between the measured gaps between the bobbin (1) and spindle (3) surfaces and the sensor, using a known spindle diameter (d). The gap for the spindle is formed by the distance between the bobbin sleeve (2) surface and the sensor, and the known bobbin sleeve diameter is used to compute the bobbin diameter The sensor has a light source to generate a light beam aligned at the surface of the bobbin and/or spindle or bobbin sleeve. The reflected light is registered by a detector, which generates a gap signal which is used to give a characteristic bobbin diameter difference signal. The light beam is provided by a laser, to give a linear beam aligned at one edge of the bobbin, so that one part of the light beam falls on the bobbin surface and another part of the light beam falls on the bobbin sleeve surface. The detector registers the diffused light from the bobbin and sleeve surfaces. The assembly can have one sensor to determine the gap between it and the bobbin surface, and a further sensor to determine the gap between it and the spindle surface. The sensors are connected to each other, for the bobbin diameter to be established. Independent claim are also included for: (I) A bobbin diameter monitor system with a sensor (4) fitted with a light transmitter and receiver. The light is aligned at an edge of the bobbin (1), so that the received reflected light can be used to determine the gap (a) between the sensor and the bobbin surface and the gap (b) between the sensor and the spindle (3) surface. Preferred Features: The transmitter is a light source and the receiver is a detector. The light transmitter, light detector and the bobbin scanning point lie on three points of a triangle. One lens in the light path lies in front of the detector. The light transmitter and/or detector can be moved. Two sensor arrays can be fitted, where one registers the gap to the bobbin surface, and the other measures the gap to the spindle surface. (II) A bobbin winder, where the bobbin diameter (D) is registered continuously, and established by an evaluation unit which processes the measurement signals. Preferred Features: The signal evaluation system is linked to the gap control mechanism and the reciprocating yarn guide control.

Description

The invention relates to a method for determining a coil diameter a driven coil according to the preamble of claim 1, a front direction for determining a coil diameter of a driven coil according to the preamble of claim 8 and the use of the device in a winding machine

The method and the device are known from EP 0 816 806.

When winding a running thread into a bobbin the information is about the coil diameter currently wound is the prerequisite for success rich coil formation. For example, it determines a maximum spool diameter knife the end of winding. During winding (reel travel) occurs with increasing coil diameter a change in circumferential speed speed and thus a change in the winding speed of the thread. Such are the case when winding freshly spun or textured threads Changes undesirable. To the thread with a substantially constant Winding thread tension remains the peripheral speed during the Bobbin travel constant. To control or regulate the peripheral speed hence the knowledge of the wound coil diameter, especially in the Winding devices where the bobbin is on a driven bobbin spanned is necessary. Such a winding device is, for example, from WO 96/01222 known. Here, the coil diameter by an am  The circumference of the spool against the pressure roller is sensed. The coil diameter is calculated from the speed of rotation of the pressure roller, the Calculate the diameter of the pressure roller and the speed of rotation of the spool net. The coil diameter can only be approximated by this method determine because relative speeds between the pressure roller and the Coil and the regulated peripheral speed of the coil are not clear Assignment between the rotational speeds and the coil diameter allow.

In the method known from EP 0 816 806 and the known device device is in contact with the coil surface to determine the coil diameter go sensed. Two are arranged at a certain distance from each other Sensors are used to measure the circumferential speed by means of a runtime correlation determine the coil's tightness. The coil diameter is measured from the its peripheral speed of the coil and the speed of rotation of the spin del calculated. No relative speeds are possible with this method occur between the coil surface and the sensor, but the detected coil diameter depends on the regulated peripheral speed. So that is This method is also unsuitable for an exact determination of the coils diameter to perform.

It is therefore an object of the invention, a method and an apparatus for loading to create a coil diameter of a driven coil that or an exact determination of the coil diameter regardless of the Circumferential speed of the coil allows.

Another object of the invention is to provide a driven winding machine To further develop the winding spindle so that all control and regulation processes during the winding travel regardless of a relative speed between the Coil and a pressure roller lying on the circumference of the coil can be.  

This object is achieved according to the invention by a method with the features according to claim 1, with a device with the features according to claim 8 and by a winding machine with the features of claim 13, 14 and 15 solved.

The invention is characterized in that the coil diameter is determined by position measurements. Here, a sensor is arranged at a distance from the coil surface. The sensor detects the distance (coil distance) between the sensor and the coil surface and detects the distance (spin delabstand) between the sensor and the spindle surface. The coil diameter can then be determined by simple calculation, provided that the spin diameter is known. If the coil distance is designated a, the spindle distance b and the diameter of the spindle d, the following equation results for the coil diameter D:

D = d + 2 (b - a).

The particular advantage of the invention is that it is independent of the ever because winding device an accurate determination of the coil diameter enables. The coil can therefore lie on the circumference of the coil driving roller or driven by a spindle receiving the spool become.

A particularly advantageous method variant according to claim 2 is in particular suitable for a fixed winding spindle. This is at the beginning of the winding trip the spindle distance is measured by the sensor. Since the spindle distance during If the winding travel remains constant, a further measurement is not necessary. To Be Coil diameter is adjusted during the bobbin travel detected. The coil diameter is then determined from the above  sleeve diameter as well as the saved spindle distance and the ak currently determined coil spacing.

The development of the method according to claim 3 enables a distance measurement according to the triangulation principle. Here is a point of light on the projected surface projected. The Si reflected from the light point Signals are imaged on a detector. From the location of the location the distance to the surface can be determined. This process variant is especially suitable to measure a large number of measurements within a very short time conditions. This enables a continuous determination of the coils diameter during the winding cycle. Can be used as light sources advantageous LEDs are used. As detectors, for example se photodiodes can be used.

In order to obtain a light beam that is bundled as strongly as possible, the light beam preferably generated by a laser or a laser diode. So that can create an intense point of light on the scanned surface.

In an advantageous development of the method, the light beam is lines shaped in such a way on an edge of the coil that part of the light rays onto the coil surface and part of the light rays onto the sleeve surface falls. This makes it possible to measure the coil spacing with just one measurement and determine the spindle distance.

The advantageous method variant according to claim 7 is characterized in that that the light source and the detector are independent of the reflection laws can be arranged. The method thus enables the use of a particularly compact device.

In a particularly preferred development of the method, the coil distance and the spindle distance is detected by a sensor. This procedure  Ren can be used particularly in winding machines where the winding spindle is arranged on a movable support. Here the coil changes stood and the spindle distance during the winding travel. The sensors preferably arranged in one plane. If the position of the sensors is different the difference in position of the sensors when calculating the coil diameter consider.

The device according to the invention essentially consists of a sensor and evaluation electronics. So that the device can be in any kind of Integrate rewinders. The sensor consists of a transmitter and a recipient. Signals are generated by the transmitter and in the direction of surface to be scanned. The reflected signals from the sampled Surface are picked up by the receiver and converted into a distance signal transferred. The distance signal is given to the evaluation electronics. After this the coil distance and the spindle distance are measured, the coils diameter calculated using the evaluation electronics. This is the spindle diameter or the sleeve diameter stored in the evaluation electronics. An ultrasound can be generated as a sensor signal, for example.

The development of the device according to claim 9 is particularly advantageous. Here, an optoelectric sensor based on the triangulation principle ar processed, used. This is a very precise determination of the coil diameter sers possible, which is essentially independent of the environment.

To intensify the light rays can both in front of the light source as well lens systems can be used in front of the detector.

When using a sensor, it is particularly advantageous if according to An saying 11 the transmitter and / or the receiver are designed to be movable. In order to different surface areas can be scanned so that a detection  solution of the spindle distance and the coil distance one after the other Sensor is possible.

The use of the device according to the invention or the application of the The inventive method in a winding machine in which the bobbin is placed on a driven winding spindle by means of a sleeve completely new regulation and control concepts. In the state of the art Known winding machines, the peripheral speed of the coil is by means of a pressure roller resting on the circumference of the coil is regulated. For this, the Speed of the pressure roller by regulating the spindle drive to one regulated approximately constant value. The problem arises that slip phenomena between the pressure roller and the spool surface to a " rapid "or" too slow "peripheral speed leads.

The winding machine according to the invention, however, has the Advantage that for each coil diameter, the corresponding circumferential directly speed is adjustable. So that the thread can be during the winding trip wind with even thread tension.

Another problem with the winding machines known in the prior art is that in the case of a pressure roller resting on the coil circumference Center distance between the spindle and the pressure roller during the winding cycle must change to allow coil formation. The pressure is on roll the task to a predetermined contact pressure on the coil surface generate so that even thread placement on the bobbin surface ent stands. Through the double function "sensing coil diameter and pressing force generate "irregularities of one or the other Function.

The winding machine according to the invention, however, enables an essentially continuous change in distance between the spindle  and the pressure roller, without that from the pressure roller on the spool applied contact pressure is influenced. The evaluation electronics of Ab level sensors connected to the distance control. From the individual be Coil diameters can be increased per coil diameter Determine the unit of time so that the moving spacing increases the center distance ger can be driven continuously.

When winding the thread on the bobbin, the thread is chan yaw device back and forth within a traversing stroke, so that a Cheese is wound. Here are different types of windings under the names "wild winding", "precision winding" and "stages precision winding "are known. For all types of windings, ge care is taken that no image windings are generated. Under image wraps it is understood here that threads of different layers are placed directly on top of one another become. The image windings arise primarily with an integer Relationship between the traversing frequency and the speed of the spindle. That I the speed of the spindle changes with increasing diameter, He Apparitions of the image windings only through known starch processes of the Changier to avoid frequency. Here is the exact specification of the coil diameter desirable for predicting a mirror. By the fiction moderate winding machine according to claim 15 can with the traversing interference high precision. The evaluation electronics of Ab level sensors connected to the traversing control.

In the following the method according to the invention and the fiction moderate device described with reference to some embodiments.

They represent:

Figures 1 and 2 schematically two embodiments of an apparatus according to the invention;

FIGS. 3 and 4 schematically show two embodiments of a winding machine according to the invention.

In Fig. 1 a first embodiment of the device according to the invention. The device consists of a sensor 4 which is fixedly arranged at a distance from a winding spindle 3 . The distance is referred to as the spindle distance and is marked with the letter b. The winding spindle 3 is connected to a drive (not shown here) and is driven at a predetermined speed. On the spindle 3 , a sleeve 2 is attached and clamped ver. On the sleeve 2 , a thread 7 is wound into a bobbin 1 . For this purpose, the thread 7 is guided back and forth within a traversing stroke by means of a traversing thread guide 8 before it hits the bobbin surface.

To determine the coil diameter, which is identified by the letter D in FIG. 1, the sensor 4 generates signals which strike the surface of the spin del 3 and the surface of the coil 1 . The instantaneous distances between the sensor 4 and the spindle 3 and the coil 1 are determined from the signals reflected by the respective surfaces. The coil distance is identified in FIG. 1 with the letter a and defines the distance between the sensor 4 and the surface of the coil 1 . After the spindle distance b and the coil distance a have been determined, the coil diameter D is determined by means of evaluation electronics according to the formula

D = d + 2 (b - a)

calculated. The spindle diameter d is a known variable in the out value electronics deposited.

The measurement of the bobbin diameter is carried out continuously at short intervals during the bobbin travel. In the case of a stationary winding spindle, the spindle distance b remains constant during the winding travel. This means that the ongoing measurement of the spindle distance b can be omitted. In this case, the spindle distance b is given to the evaluation electronics as a constant value. During the winding cycle, the constantly changing bobbin distance is measured by the sensor 4 . Thus, all can be determined by determining the distance of the currently wound coil diameter D.

In Fig. 2 another embodiment of a Vorrich device according to the invention is shown. The figure is shown in a view. The coil 1 is clamped on the winding spindle 3 by means of the sleeve 2 . On the reel 1, the yarn is wound on 7, wherein the back yarn 7 by means of the traversing yarn guide 8 within the coil width and is brought hither. On the circumference of the coil 1 is a driven drive roller 9 . Thus, the spool 1 is driven by the drive roller 9 at a substantially constant peripheral speed. A sensor 4 is arranged at a distance from the winding spindle 3 . The sensor 4 consists of a transmitter 6 and a receiver 5 . The transmitter 6 can be designed as a light source, for example a laser diode. The receiver 5 is out as a detector. The transmitter 6 generates a light signal which strikes the coil surface of the coil 1 and the sleeve surface of the sleeve 2 . The receiver 5 picks up the reflected light from the light projected onto the surfaces. A triangle is spanned by the transmitter 6 , the projected light point and the receiver 5 .

In contrast to the embodiment from FIG. 1, the spindle distance is formed by the distance between the sensor 4 and the surface of the sleeve 2 in the embodiment from FIG. 2. To distinguish the Spindelab stood in Fig. 2 with the letter b '. The calculation of the coil diameter D is carried out according to the same procedure as has already been described for FIG. 1. The evaluation electronics is specified here as the value of the sleeve diameter d 'of the sleeve 2 . Since the coil distance and the spindle distance change with increasing coil diameter, the distances a and b 'are detected by the sensor with each determination of the coil diameter and the associated coil diameter is calculated according to the formula given.

In Fig. 3 a first embodiment of a winding machine according to the invention is shown. In Fig. 3, the winding machine is shown in a front view. The winding machine has a winding turret 19 which is rotatably mounted in a machine frame 21 by means of a bearing 20 . The winding turret 19 is driven by the drive 24 in the direction of rotation indicated by an arrow bar. On the turret 19 , a rotatable spindle 3 is cantilevered. The spindle 3 is driven by a spindle drive (not shown here). The spindle 3 carries a clamped sleeve 2 . A thread 7 is wound on the sleeve 2 to form a bobbin 1 . The thread 7 is supplied to the winding machine at a constant speed. The thread 7 is guided by a top thread guide 10 , which forms the tip of the traversing triangle. The thread 7 passes from the top thread guide 10 to a traversing device, which is designed as wing traversing, with the wings 13 . Here, two wing pairs are driven in opposite directions by a traversing drive 11 , so that the Fa 7 is alternately guided back and forth by the wings 13 within a traversing stroke. The traversing device is attached to a carrier 12 .

Behind the traversing device, the thread 7 is deflected at a pressure roller 14 at more than 90 ° and then wound on the spool 1 . The pressure roller 14 is rotatably mounted on the free end of a carrier 15 . The pressure roller 14 lies against the circumference of the coil 1 .

A sensor 4 with evaluation electronics 16 is attached to the carrier 15 . The sensor 4 has a transmitter 6 and a receiver 5 . The evaluation electronics 16 is connected to a distance control 25 . The distance control 25 is coupled to control the drive 24 with the drive 24th

In the winding machine shown in FIG. 3, the thread 7 is continuously wound on the bobbin 1 . In order to allow the increasing coil diameter of the coil 1 , the spindle 3 is pivoted in the direction of the arrow by the winding turret 19 . For this purpose, the drive 24 is controlled by the distance control 25 . The movement of the winding turret is controlled as a function of the increasing bobbin diameter. The coil diameter of the coil 1 is detected by the sensor 4 . For this purpose, the transmitter 6 generates a light signal which strikes the surface of the coil 1 and the surface of the spindle 3 . The light spots projected on the surfaces are reflected. The reflected light signals are collected by the receiver 5 and converted into distance signals for the coil spacing and for the spindle spacing. In the evaluation electronics 16 , the associated coil diameter is determined and the distance control 25 is abandoned. The distance controller 25 then controls the drive 24 of the winding turret 19 . It can be assigned by the distance control 25 for example to a specific position of the turret verse for each coil diameter. The drive turret 24 thus moves the winding turret into the corresponding position. However, it is also possible that a speed of the winding turret is assigned to each spool diameter. This method is particularly suitable for obtaining a continuous movement of the bobbin volver 19 .

In the winding machine shown in Fig. 3, the carrier 15 can be movably or fixedly attached to the machine frame.

In Fig. 4, another embodiment of a winding machine according to the invention is shown schematically in cross section. The structure is identical to the winding machine shown in FIG. 3. In this respect, reference is made to the description given above and essentially only the differences from the previous exemplary embodiment are described.

The winding spindle 3 is cantilevered on the winding turret 19 by means of a bearing 27 . At the bearing end of the spindle 3 , the spindle 3 is connected to a spin drive 22 . On the projecting end of the spindle 3 , the sleeve 2 is stretched, on which the thread 7 is wound into a bobbin 1 . Two sensors 17 and 18 are arranged at a distance from the spindle 3 . The sensors 17 and 18 are combined with the evaluation electronics 16 to form one structural unit. The evaluation electronics 16 is connected to a drive control 23 . The drive control 23 is coupled to the spindle drive 2 for regulating the spindle speed 3 .

As described in the previous embodiment, the evaluation electronics 16 is also connected to the distance control 25 , which moves the winding turret 19 via the drive 24 to carry out the evasive movement of the spindle 3 during the winding of the coil 1 .

The evaluation electronics 16 is also connected to a traverse control 26 in the winding machine shown in FIG. 4. The traversing control 26 is coupled to the traversing drive 11 in order to control the traversing frequency in accordance with predetermined winding laws.

To determine the coil diameter during the winding trip, the sen sensors 17 and 18 each generate signals that lead to a distance measurement. The sensor 17 generates signals for determining the spindle distance, which currently prevails between the surface of the spindle 3 and the sensor 17 . The sensor 18 generates signals for determining the coil distance, which is present at the measuring time between the coil surface of the coil 1 and the sensor 18 . From the respective distance signals to the coil distance and to the spindle distance, the evaluation electronics 16 determines a difference signal which corresponds to the coil diameter currently being wound. This difference signal is given to the drive control 23 . In the drive control 23 , a master curve is stored, in which a specific speed of the spindle 3 is assigned to each coil diameter, so that the peripheral speed of the coil 1 remains constant during the winding travel.

The difference signal of the evaluation electronics 16 is used in the distance controller 25 to control the evasive movement of the winding spindle - as has already been described for the exemplary embodiment according to FIG. 3.

In order to avoid image windings during the winding trip, the differential signals are evaluated in the chaning control 26 . Here, for example, the current growth rates of the coil can be used in order to avoid any impending image windings by changing the traversing frequency.

In the previously described embodiments of the invention the sensors can perform additional functions such as Carry out thread run monitoring or winder monitoring.

In winding machines where there are several bobbins on the winding spindle can be wound at the same time, for example, the Spu Len distance measurement of two adjacent coils taken over by a sensor become. A lens system could, for example, be a linear one Light beam are focused so that the edge areas of the neighboring Coil surfaces and the space with the spindle between the coils is detected. A height profile can be created using a corresponding receiver Measure from which the coil diameter of both coils can be calculated.

Since the position between the sensor and the spindle varies constantly in the exemplary embodiments shown in FIGS. 3 and 4, transmitters are advantageously used which generate scattered light signals. This ensures that the surfaces are scanned in every position. When using light sources with point-shaped light signals, such changes in position can be compensated for, for example, by moving sensors. The movement of the sensor could be coupled with the evasive movement of the spindle or the evasive movement of the pressure roller.

Reference list

1

Kitchen sink

2nd

Sleeve

3rd

spindle

4th

sensor

5

Receiver, detector

6

Transmitter, light source

7

thread

8th

Traversing thread guide

9

Drive roller

10th

Head thread guide

11

Traverse drive

12th

carrier

13

wing

14

Pressure roller

15

carrier

16

Evaluation electronics

17th

sensor

18th

sensor

19th

Winding turret

20th

camp

21

Machine frame

22

Spindle drive

23

Drive control

24th

drive

25th

Distance control

26

Traversing control

27

camp

Claims (15)

1. A method for determining a bobbin diameter of a driven bobbin, in which an incoming thread is wound on the bobbin, for which purpose a bobbin receiving sleeve is attached to a rotatable spindle, and in which the bobbin surface is at a distance (bobbin distance) to the bobbin surface Arranged sensor is sensed without contact, characterized in that the coil len distance between the sensor and the coil surface and a spindle distance between the sensor and the spindle surface is detected and that the coil diameter from the predetermined diameter of the spindle and the difference between the spindle distance and the coil distance is determined. 2. The method according to claim 1, characterized in that the spin delabstand by the distance between the sensor and the sleeves Surface is formed, with the determination of the coil diameter the sleeve diameter is specified. 3. The method according to claim 1 or 2, characterized in that the Sensor generates a light beam by means of a light source, which on the coil surface and / or the spindle surface / sleeve surface is directed that the reflected light from the coil surface and the reflected light from the spindle surface / sleeve surface of the sensor recorded by means of a detector and at a distance signals is transferred, and that a characteristic of the coil diameter generating differential signal is generated from the distance signals. 4. The method according to claim 3, characterized in that the light beam is generated by a laser.   5. The method according to any one of claims 3 or 4, characterized in that the light beam is directed in a linear manner onto an edge of the coil is that part of the light rays hit the coil surface and part the light rays fall on the surface of the sleeve. 6. The method according to any one of claims 3 to 5, characterized in that the diffusely reflected light of the coil surface and the diffuse right reflected light from the spindle surface / sleeve surface from the detector gate is included. 7. The method according to any one of the preceding claims, characterized records that a sensor for detecting the coil distance and another rer sensor is used to detect the spindle distance, whereby the sensors for determining the coil diameter are connected to one another they are. 8. Apparatus for determining a coil diameter of a driven bobbin ( 1 ) which is formed by winding an incoming thread ( 7 ), the coil ( 1 ) being attached to a rotatable spindle ( 3 ) by means of a sleeve ( 2 ) , with a sensor ( 4 ) which was at a distance (coil distance) (a) to the coil surface and which senses the coil surface without contact, characterized in that the sensor ( 4 ) has a transmitter ( 6 ) and a receiver ( 5 ), wherein the transmitter ( 6 ) sends directional signals on the coil surface and / or on the spindle surface / sleeve surface and wherein the receiver ( 5 ) receives the reflected signals and in a status signal for the coil distance (a) and in a distance signal for egg NEN spindle distance (b) transferred, and that an evaluation electronics ( 16 ) is provided, the coil diameter from the distance signals and a predetermined spindle diameter / sleeve diameter esser determined. 9. The device according to claim 8, characterized in that the transmitter ( 6 ) is a light source and that the receiver ( 5 ) is a detector, the light source and the detector enclose a triangle with a be determined by the light beam scanning point on the surface . 10. The device according to claim 9, characterized in that a lens is arranged in the beam path in front of the detector. 11. The device according to one of claims 8 to 10, characterized in that the transmitter ( 6 ) and / or the receiver ( 5 ) are designed to be movable. 12. The device according to one of claims 8 to 11, characterized in that a second sensor ( 18 , 17 ) is arranged at a distance from the spindle, one of the sensors ( 17 ) of the coil surface and the other of the sensors ( 18 ) of the spindle surface assigned. 13. winding machine for winding a thread into a bobbin ( 1 ), with a driven spindle ( 3 ), on which a spool ( 1 ) receiving sleeve ( 2 ) is attached, and with a drive control ( 23 ) for control of the spindle speed such that the coil ( 1 ) maintains a constant peripheral speed during winding (winding travel), the peripheral speed changing as a function of the diameter (D) of the coil ( 1 ), characterized in that a device having the features of one of the Claims 8 to 12 is provided to continuously determine the coil diameter (D) and that Auswertelek electronics ( 16 ) of the device is connected to the drive control ( 23 ). 14. Winding machine for winding a thread ( 7 ) to a bobbin ( 1 ), with a driven spindle ( 3 ), on which a spool ( 1 ) receiving sleeve ( 2 ) is attached, with a pressure roller ( 14 ) abuts the circumference of the coil ( 1 ), and with a distance control ( 25 ) for controlling the center distance between the spindle. ( 3 ) and the pressure roller ( 14 ), the center distance changing depending on the diameter (D) of the spool ( 1 ) and the spindle ( 3 ) and / or the pressure roller ( 14 ) on a drivable movable carrier ( 19 ) is mounted, characterized in that a device with the features of one of claims 8 to 11 is provided in order to continuously determine the coil diameter, and that evaluation electronics ( 16 ) of the device are connected to the distance control ( 25 ). 15. Winding machine for winding a thread ( 7 ) into a bobbin ( 1 ), with a driven spindle ( 3 ), on which a sleeve ( 2 ) receiving the bobbin ( 1 ) is attached, with a traversing device ( 11 , 13 ) which guides the thread ( 7 ) back and forth for depositing on the bobbin surface within a traversing stroke, and with a traversing control ( 26 ) for controlling the traversing frequency of the traversing device ( 11 , 13 ), the traversing frequency changing as a function of the increase in the bobbin diameter is characterized in that a device with the features of one of claims 8 to 11 is vorgese hen to continuously determine the coil diameter, and that evaluation electronics ( 16 ) of the device is connected to the traversing control ( 26 ).