GB1601523A

GB1601523A - Method and apparatus for winding threads into a conical bobbin package

Info

Publication number: GB1601523A
Application number: GB1918878A
Authority: GB
Original assignee: Barmag Barmer Maschinenfabrik AG
Current assignee: Oerlikon Barmag AG
Priority date: 1977-05-14
Filing date: 1978-05-12
Publication date: 1981-10-28
Also published as: JPS5415042A; DE2721972B2; DE2721972A1; DE2721972C3

Description

(54) METHOD AND APPARATUS FOR WINDING THREADS INTO A CONICAL BOBBIN PACKAGE (71) We, BARMAG BARMER MASCHINENFABRIK AKTIEN GESELLSCHAFT a body corporate organised under the laws of the Federal Republic of Germany, of Remscheid Lennep, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a method of and an apparatus for winding threads into a conical bobbin package.

When winding threads variations in the winding speed or, in the case of threads which are supplied at a defined speed, variations in the thread tension occur owing to the traversing movement. Moreover, the winding speed also changes in the course of bobbin travel during the production of conical bobbin packages.

In order to compensate for these variations in speed and/or thread tension the drive speed of the bobbin is usually changed so as to prevent these variations acting on the preceding thread production process (spinning process) or thread processing process (for example texturising or twisting).

The alteration in the drive speed of the bobbin gives rise to difficulties particularly when the bobbin is driven by means of drive rollers. These drive rollers are usually fixed on a shaft which is driven by a central motor and extends through the entire machine.

In order to solve the problem of driving an individual bobbin at a changing speed despite the use of a central drive, winding machines are described in German Patent No. 711 324 in which the bobbin is driven by a drive roller whose diameter varies along the axis thereof and at the level of the shaft of the bobbin and drive rollers, is pivoted to and fro about an axis extending transversely to the axis of the bobbin and drive rollers.

The length of the thread between the traversing and running-on position and thus also the length of the bobbin changes during this pivoting movement of the bobbin in each case. In addition, the layers of thread on the edges not contacting the drive roller tend to slough off so that the bobbin package produced has very undesirable unwinding properties.

It is known from German Patent No.

485;350 to displace a ball-shaped drive roller axially during the production of conical bobbin packages. In so doing, however, the surface of the bobbin is damaged and sloughing layers of windings are again formed in the edge regions.

It is proposed to German Auslegeschrift No. 19 12 374 that the drive roller consist of at least two coaxial sections which are arranged to be freely rotatable on the drive roller shaft and can be coupled to the drive roller shaft in dependence upon the delivery rate of the wound thread. Such a construction, however, is complicated and expensive and does not ensure continuous adjustment of the winding speed.

The above proposals are all based on the idea of displacing the area of contact between bobbin and drive roller so as to alter the gear ratio between drive roller and bobbin. This displacement of the point of contact is extremely undesirable in that it leads to a poor bobbin package build-up and to damage of the thread.

It is proposed in German Patent No. 23 28 993 to change the gear ratio between the control shaft drive at a constant speed and the drive roller casing by means of a bevel gear arranged in the drive roller.

The object of the invention is to provide a simple method of and apparatus for winding conical bobbin packages by means of which the winding speed may be adjusted at a constant speed of the drive roller without damaging the thread, the surface of the bobbin and the bobbin package build-up.

According to the invention there is provided a method of winding a thread into a conical bobbin package, wherein the thread is supplied at a constant delivery speed, is stored in a thread store, and thereafter wound into the said package, wherein the bobbin is driven by means of a drive roller which rotates at a constant speed and which engages the surface of the bobbin package along an area of contact, the amount of thread in the thread store being monitored wherein variations of said amount of thread cause a change in the distribution of pressure between the bobbin package and the drive roller along the said area of contact, and said change causing the winding speed of the bobbin to be altered without altering the speed of the drive roller.

It is particularly advantageous for the pressing force between the bobbin and drive roller to remain constant during the change in the distribution of the pressure. It should be explained, however, that this does not rule out the possibility of the pressing force between the bobbin and the drive roller being changed over the path of the bobbin travel, whether as a result of the increasing weight of the bobbin package, as a result of the application of springs or as a result of other structural measures (cf., for example, German Patent No. 21 45 989 in this respect).

The present invention based on the provision of a variable distribution of the pressure between bobbin and drive roller for controlling the winding speed without the bobbin rising from the drive roller. The geometric pivoting movements between the bobbin and the drive roller required for this purpose do not amount to more than a few tenths of a millimetre with conventional bobbin sizes and are usually invisible to the naked eye.

The invention also provides a winding apparatus for winding a thread into a conical bobbin package, comprising a drive mechanism including a drive roller which is drivable at a constant speed and which bears against the bobbin package along a predetermined area of contact, a thread store arranged upstream of the winding apparatus, a monitoring device for monitoring the quantity of thread stored, a controllable force transmitter controlled by the monitoring device, and a bobbin holder which is pivotal about an axis which crosses the spool axis, the force transmitter acting pivotally on the bobbin holder in such a way that a torque which may be altered depending upon the quantity of thread stored acts on the bobbin package so as to change the distribution of pressure between the bobbin package and the drive roller, which torque is such that the bobbin package remains in contact with the drive roller along the said predetermined area of contact.

Preferably the drive roller and bobbin are pivotal relative to each other about a pivoting axis which is substantially perpendicular to their common axial plane and lies in or near to the common tangential plane of bobbin and drive roller.

There operates between the bobbin and the drive roller a pressing force, produced, for example by a weight, an energy store, or by frictional forces and also, without opposing influence, a torque free from any transverse force component. The pressing force thus remains constant even when the distribution of the pressure varies.

Using the invention it is possible, with a thread which is supplied at a constant delivery rate, to compensate completely the variations in the winding speed which are produced by the traversing movement and by the increasing bobbin package diameter of the conical bobbin and in particular to avoid unacceptable thread tensions, by intermediate storage of the thread in a thread store arranged in front of the winding position. A preferred example of such a thread store is a rotatably driven roller on which the thread is wound tangentially and drawn off over-end via an unwinding brake. The monitoring device monitors the number of thread windings formed on the roller. This monitoring device at the same time controls a pneumatic valve. The pressure in a pneumatic cylinder and piston unit is influenced by this valve while the cylinder and piston unit pivots the bobbin in relation to the drive roller about a pivoting axis crossing the bobbin axis.

The invention is described in more detail below with reference to the accompanying drawings, in which: Fig. 1 shows a winding apparatus for conical bobbins with adjustment of the winding speed for controlling the quantity of thread; Fig. Ia shows in detail a suitable monitoring sensor; and Figs. 2a to 2c are diagrammatic illustrations of the winding of conical bobbin packages.

Fig. 1 shows a thread 18 being wound to a conical bobbin package 1. The conical bobbin package is rotatably mounted between the arms of the bobbin holder 2.

One of the arms is pivotal under spring force. The bobbin holder 2 is pivotal about a shaft 3. The conical bobbin package 1 rests under its own weight and the weight of the bobbin holder 2 on a drive roller 8. A strut 4 with a spring-loaded sliding block 5 by means of which a frictional force increasing the pressing force is exerted on the pivotal bobbin holder 2 is used for modifying the pressure between bobbin 1 and feed roller 8.

The shaft 3 of the bobbin holder is mounted in a support 6. The support 6 is pivotal about an axis 7. The axis 7 lies approximately on the common tangent to the bobbin I and the drive roller 8 at the centre of the area of contact between the bobbin and the drive roller. The drive roller 8 is mounted on a shaft 9. A plurality of drive rollers 8 are usually mounted on a single shaft 9 in a machine. The shaft 9 is driven bv a motor in the centre of the machine. The traversing of the thread is effected by a thread guide 10 which is reciprocated by a reversing screw-threaded shaft 11.

A torque is applied about the axis 7 by a force transmitter, in this example by a pneumatic cylinder and piston unit 12, which acts on the side of the support 6 remote from the strut 4. The pneumatic cylinder is once subjected via a control line 25 to a control pressure P2, the value of which may be adjusted as desired, by an adjustable pressure-reducing valve 13.

On the other side of the piston, the pneumatic cylinder is charged via a control line 24 with a control pressure P,. In the embodiment, P, is dependent upon a quantity of thread 14 which is formed on a thread store on a cantilevered roller 15.

The thread 18 is produced or processed at a constant rate in a device 26, which may be a spinning device or, for example, a texturing device. The roller 15, which is mounted on a shaft 16, is driven at a constant speed adapted to the rate of production or processing, and draws the thread from the device 26. The thread is thus wound into windings to form the store of thread 14 on the roller. The store of thread is displaced axially parallel to the free end of the roller 15 by a springmounted feed shoe 17. The thread is then drawn off over-end of the roller 15 and, in the process, is braked with a predetermined braking force. The brake may, for example, be of the type shown in Patent No.

1,430,339. The displacement of the feed shoe 17 alters the control pressure P,. The control pressure P, may be pre-adjusted by the adjustable pressure-reducing valve 27.

The control line 24 is branched downstream of the throttle 23. One branch opens into a control cylinder 20 which is shown in detail in Fig.

Ia. A piston 19 which is rigidly fixed to the feed shoe 17 is received in the control cylinder 20. The cylinder 20 has an outlet opening 22. The air in the control line 24 can thus escape through the outlet opening 22 depending upon the position of the piston 19 and accordingly upon the quantity of stored thread 14. The control pressure P, thus varies depending upon the quantity of thread 14. The difference between the control pressure P1 and the control pressure P2 transmits a force to support 6 which produces a torque about the pivoting axis 7.

This torque causes the pressure distribution to vary over the length L of the area of contact between bobbin 1 and drive roller 8, without changing the total pressing force, and accordingly varies the winding speed of the bobbin package 1. The range of possible variations in the distribution of pressure load is shown in Figs. 2a to 2c.

The conical bobbin is subjected to a pressing force G, which is constant in time but which, as already described is variable in the paths of the bobbin travel owing to the increasing weight of the bobbin package or as the result of other factors. G is given by c=Jb' pdl, where p is the pressure over a length dl.

The variation of the value of p with 1, can be varied by applying an additional moment which acts in the common axial plane of drive roller and bobbin. A moment which has been compensated with respect to its transverse forces is preferably applied for this purpose so as to avoid a change in the pressing force G.

In Fig. 2a, the torque M causes the pressure to decrease from the thin end of the bobbin package to the thick end. The winding speed is thus increased while the speed of the drive roller remains constant.

With regard to the winding speed, it should generally be noted that the winding speed changes in the course of a traversing stroke when winding conical bobbin packages. Therefore, when "winding speed" is mentioned in the context of this invention in conjunction with conical bobbin packages, this refers to the average winding speed V, which is given by T v dt V=r o T where v is the winding speed in time, t the time and T the total integration period.

Fig. 2b shows no additional moment acting on the bobbin package. Here, the pressure is uniform over the contacting stretch L. The speed will correspondingly remain the same.

In Fig. 2c, a moment is introduced in such a way that the pressure diminishes from the thick end of the bobbin package to the thin end. The winding speed is thus decreased while the speed of the drive roller remains constant.

The control system shown in Fig. 1 functions sensitively so that the extreme cases shown in Figs. 2a and 2c do not occur but that only slight changes in the moment M are produced.

It should be pointed out that the distribution of pressure may also be changed by displacing the point of contact of the pressing force of part of the pressing force in the region of the contacting stretch L, or by the pressing force or part of the pressing force being adjustable and making contact outside the centre of the contacting stretch L, for example in such a way that the proportion by weight of the pressing force in its point of contact, obviously as in itself, remains unchanged while an additional external pressing force is applied outside the centre of gravity and is adjustable either in magnitude or in its point of contact.

WHAT WE CLAIM IS: 1. A method of winding a thread into a conical bobbin package, wherein the thread is supplied at a constant delivery speed, is stored in a thread store, and thereafter wound into the said package, wherein the bobbin is driven by means of a drive roller which rotates at a constant speed and which engages the surface of the bobbin package along an area of contact, the amount of thread in the thread store being monitored wherein variations of said amount of thread cause a change in the distribution of pressure between the bobbin package and the drive roller along the said area of contact, and said change causing the winding speed of the bobbin to be altered without altering the speed of the drive roller.

2. A method according to claim 1, wherein the average pressure remains unaltered when the distribution of pressure is changed.

3. A method of winding a thread into a conical bobbin package substantially as herein described with reference to the accompanying drawings.

4. A winding apparatus for winding a thread into a conical bobbin package, comprising a drive mechanism including a drive roller which is drivable at a constant speed and which bears against the bobbin package along a predetermined area of contact, a thread store arranged upstream of the winding apparatus, a monitoring device for monitoring the quantity of thread stored, a controllable force transmitter controlled by the monitoring device. and a bobbin holder which is pivotal about an axis which crosses the spool axis, the force transmitter acting pivotally on the bobbin holder in such a way that a torque which may be altered depending upon the quantity of thread stored acts on the bobbin package so as to change the distribution of pressure between the bobbin package and the drive roller, which torque is such that the bobbin package remains in contact with the drive roller along the said predetermined area of contact.

5. An apparatus according to claim 4, wherein the drive roller is mounted on a common, centrally driven shaft with the drive rollers of a plurality of similar winding apparatuses, each bobbin holder being pivotal by a controllable force transmitter.

6. An apparatus according to claim 3 or 4, wherein the thread store is a roller rotatably drivable at a constant circumferential speed, on which the thread is wound tangentially and is drawn off overend via an unwinding brake, the said monitoring device detecting the quantity of thread formed by a number of windings on the roller and the force transmitter being controlled as a function of the output signal from the monitoring device.

7. An apparatus according to claim 6, wherein the thread store draws the thread from a preceding production and/or processing zone.

8. An apparatus according to one of claims 4 to 7, wherein the force transmitter is a pneumatic cylinder and piston unit to which is connected a pressure line provided with a valve which is actuated by the said monitoring device.

9. An apparatus for winding a thread into a conical bobbin package, substantially as herein described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. It should be pointed out that the distribution of pressure may also be changed by displacing the point of contact of the pressing force of part of the pressing force in the region of the contacting stretch L, or by the pressing force or part of the pressing force being adjustable and making contact outside the centre of the contacting stretch L, for example in such a way that the proportion by weight of the pressing force in its point of contact, obviously as in itself, remains unchanged while an additional external pressing force is applied outside the centre of gravity and is adjustable either in magnitude or in its point of contact. WHAT WE CLAIM IS:

1. A method of winding a thread into a conical bobbin package, wherein the thread is supplied at a constant delivery speed, is stored in a thread store, and thereafter wound into the said package, wherein the bobbin is driven by means of a drive roller which rotates at a constant speed and which engages the surface of the bobbin package along an area of contact, the amount of thread in the thread store being monitored wherein variations of said amount of thread cause a change in the distribution of pressure between the bobbin package and the drive roller along the said area of contact, and said change causing the winding speed of the bobbin to be altered without altering the speed of the drive roller.