Yarn tensioning system and method for keeping a yarn which is taken from a yarn storage system to a yarn take-off system of a weaving machine under tension

Abstract

A yarn tensioning system (1) for keeping at least one yarn (2) which is taken from a yarn storage system (3) to a yarn take-off system (4) of a weaving machine under tension, comprising a brake roller (5) around which the yarn (2) is at least partially wound and a motor (6) for supplying a torque to the brake roller (5), which is actuable in generator operation to keep the yarn (2) under tension between the brake roller (5) and the yarn take-off system (4). In addition, a weaving machine comprising such a yarn tensioning system (1) and a method for keeping at least one yarn (2) under tension which is taken from a yarn storage system to a yarn take-off system.

Claims

1. Yarn tensioning system for keeping at least one yarn which is taken from a yarn storage system in a first direction to a yarn take-off system of a weaving machine under tension, comprising: a brake roller which is rotatably arranged in the yarn tensioning system and around which the at least one yarn is at least partially wound in order to keep the at least one yarn under tension between the brake roller and the yarn take-off system, wherein the yarn tensioning system comprises a motor for supplying a torque to the brake roller, wherein the motor is actuable in generator operation to keep the at least one yarn under tension, and wherein the motor is actuable in motor operation to recuperate the at least one yarn between the brake roller and the yarn take-off system in a second direction which is opposite to the first direction, and a time monitor to keep track of a time during which the motor operates in motor operation to recuperate the at least one yarn and to compare the time with a certain reference value, the yarn tensioning system thereby allowing a user to detect breakage of the at least one yarn without using a tension measuring device.

2. Yarn tensioning system according to claim 1, characterized in that the yarn tensioning system comprises a funnel-shaped guide for guiding the yarn to the brake roller.

3. Yarn tensioning system according to claim 2, characterized in that the yarn tensioning system comprises a tubular guide for guiding the yarn to the funnel-shaped guide.

4. Yarn tensioning system according to claim 1, characterized in that the motor is individually actuable.

5. Yarn tensioning system according to claim 1, characterized in that the yarn tensioning system comprises a central control unit and means for making the energy generated during the generator operation of the motor immediately available to this control unit of the yarn tensioning system.

6. Yarn tensioning system according to claim 1, characterized in that the yarn tensioning system comprises energy storage for storing the energy generated during the generator operation of the motor, so that the motor is driven by the stored energy during the motor operation of the motor.

7. Yarn tensioning system according to claim 1, characterized in that the yarn tensioning system comprises a measure for determining the length of the yarn which is taken off by the yarn take-off system.

8. Yarn tensioning system according to claim 1, characterized in that the yarn tensioning system comprises a communicator for receiving signals from the yarn take-off system with regard to the operation of the yarn take-off system, comprises a measurer for measuring parameters for the operation of the yarn tensioning system and comprises a tension monitor for monitoring the parameters for the operation of the yarn tensioning system relative to the received signals of the yarn take-off system.

9. Yarn tensioning system according to claim 1, characterized in that the yarn tensioning system comprises a tension measuring device for measuring the yarn tension.

10. Yarn tensioning system according to claim 9, characterized in that the yarn tensioning system comprises an actuator for actuating the motor on the basis of the yarn tension measured using the tension measuring device and communicator for communicating the measured yarn tension from the tension measuring device to the actuator.

11. Yarn tensioning system according to claim 1, characterized in that the yarn tensioning system comprises a said brake roller and a said motor for each yarn taken from the yarn storage system.

12. Yarn tensioning system according to claim 1, characterized in that the motor is a pancake motor.

13. Yarn tensioning system according to claim 1, characterized in that the yarn tensioning system comprises a tension roller which is arranged in a clamped manner against the brake roller in the yarn tensioning system to clamp the yarn between the brake roller and the tension roller.

14. Yarn tensioning system according to claim 1, characterized in that the brake roller is provided for winding the yarn several times around it.

15. Yarn tensioning system according to claim 1, characterized in that the yarn tensioning system comprises a braking device for braking the yarn in order to prevent the yarn from slipping on the brake roller.

16. Yarn tensioning system according to claim 1, characterized in that the brake roller comprises a running surface for at least partially winding the yarn around it, in which said running surface is provided with an anti-slip layer and/or with a profiling.

17. Weaving machine, comprising a yarn storage system, a yarn take-off system for taking yarn from the yarn storage system and a yarn tensioning system to keep a yarn which has been taken from the yarn storage system by the yarn take-off system under tension between the yarn tensioning system and the yarn take-off system, wherein the yarn tensioning system is a yarn tensioning system according to claim 1.

18. Method for keeping at least one yarn which is taken from a yarn storage system in a first direction to a yarn take-off system of a weaving machine under tension, in which the at least one yarn is at least partially wound around a brake roller which is rotatably arranged in the yarn tensioning system to keep the at least one yarn under tension between the brake roller and the yarn take-off system, wherein a motor is actuated in generator operation to drive the brake roller around which the at least one yarn is at least partially wound, to keep the at least one yarn under tension, wherein the motor is actuated in motor operation to drive the brake roller to recuperate the at least one yarn between the brake roller and the yarn take-off system in a second direction, which is opposite to the first direction, and further comprising: monitoring a time during which the motor is actuated in motor operation to recuperate the at least one yarn and generating an indication when the time exceeds a certain reference value, the method thereby allowing a user to detect breakage of the at least one yarn without using a tension measuring device.

19. Method according to claim 18, characterized in that said method comprises generating an indication when the brake roller is at a standstill at a point in time when the yarn take-off system takes off yarn.

20. Method according to claim 18, characterized in that said method comprises measuring the yarn tension and actuating the motor on the basis of the measured yarn tension.

21. Yarn tensioning system according to claim 2, characterized in that the funnel-shaped guide comprises a top open end and a bottom open end, wherein the top open end is wider than the bottom open end.

22. Yarn tensioning system according to claim 3, characterized in that the funnel-shaped guide comprises a top open end and a bottom open end, wherein the top open end is wider than the bottom open end.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will now be explained in more detail by means of the following detailed description of an embodiment of a yarn tensioning system and a method according to the present invention. The sole aim of this description is to give illustrative examples and to indicate further advantages and particulars of the present invention, and can therefore by no means be interpreted as a limitation of the area of application of the invention or of the patent rights defined in the claims.

(2) In this detailed description, reference numerals are used to refer to the attached drawings, in which:

(3) FIG. 1 diagrammatically shows a first embodiment of a yarn tensioning system according to the present invention in side view with a yarn which is taken from a yarn storage system in a first direction to a yarn take-off system of a weaving machine or is recuperated in a second direction, opposite to the first direction, between the yarn tensioning system and the yarn take-off system;

(4) FIG. 2 diagrammatically shows a second embodiment of a yarn tensioning system according to the present invention in front view;

(5) FIG. 3 shows the yarn tensioning system from FIG. 2 in side view;

(6) FIG. 4 shows a third embodiment of a yarn tensioning system according to the present invention in front view, without yarn;

(7) FIG. 5 shows the yarn tensioning system from FIG. 4 partially in cutaway perspective view, without yarn;

(8) FIG. 6 shows the yarn tensioning system from FIG. 4 in perspective with yarn that is herewith tensioned.

DETAILED DESCRIPTION OF EMBODIMENTS

(9) The figures show some examples of yarn tensioning systems (1) according to embodiments of the present invention.

(10) These yarn tensioning systems (1) each comprise, for each yarn (2) to be tensioned, a brake roller (5) which is rotatably arranged and a motor (6) for supplying a torque to the brake roller (5).

(11) In the first embodiment illustrated in FIG. 1, a yarn (2) taken from a yarn storage system (3) in a first direction (A) to a yarn take-off system (4) of a weaving machine, or recuperated in a second direction (B), opposite to the first direction (A), between the brake roller (5) and the yarn take-off system (4), is wound several times around the brake roller (5) to limit slipping of the yarn (2) with respect to the brake roller (5).

(12) In order to further limit slipping of the yarn (2) with respect to the brake roller (5), this yarn tensioning system (1) furthermore comprises a braking device (7) which is arranged between the yarn storage system (3) and the brake roller (5).

(13) In order to prevent the yarn (2) from running off the brake roller (5), the brake roller (5) is provided with flanges (9) which limit the running surface (8) for the yarn (2). The running surface (8) of this brake roller (5) may be provided with an anti-slip layer by coating it, for example with rubber.

(14) In the second embodiment, which is illustrated in FIGS. 2 and 3, the yarn tensioning system (1) comprises a tension roller (10). In order to limit slipping of the yarn (2) with respect to the brake roller (5), springs (11) push the shaft (12) of this tension roller (10) towards the brake roller (5), so that the tension roller (10) is arranged in a clamped manner against the brake roller (5) to clamp the yarn (2) between the brake roller (5) and the tension roller (10).

(15) In the third embodiment, which is illustrated in FIGS. 4 to 6, the yarn tensioning system (1) is configured to keep 8 yarns (2) under tension. These yarns (2) may be, for example, warp threads (2) which are fed to a carpet weaving machine as yarn take-off system (4). To this end, the yarn tensioning system (1) comprises a brake roller (5), a motor (6) and a tension roller (10) as in the second embodiment for each yarn (2). For the sake of clarity of the figures, only one motor (6) is shown. Each yarn (2) is fed through a holder (15) via a corresponding tubular guide (14) and is passed to the corresponding brake roller (5) via a funnel-shaped guide (13), wound around this brake roller (5) and fed to the yarn take-off system in a first direction (A) through an eyelet (17). The outlet opening (16) of the tubular guide (14) is smaller than the inlet opening to the funnel-shaped guide (13). The funnel-shaped guide (13) comprises a cup-shaped cavity in which the yarn (2) is collected in the case of yarn recuperation in a second direction (B).

(16) In all illustrated embodiments, the motor (6) is a pancake motor (6) which is configured to supply a torque to the brake roller (5). On the one hand, the motor (6) is actuated in generator operation to keep the yarn (2) under tension. On the other hand, the motor (6) is actuated in motor operation to recuperate the yarn (2) between the brake roller (5) and the yarn take-off system (4) in a second direction (B), which is opposite to the first direction (A).

(17) The yarn tensioning systems (1) comprise a central control unit (not shown) and means for immediately making the energy generated during the generator operation of the motor (6) available to this central control unit of the yarn tensioning system (1). Alternatively, the yarn tensioning systems (1) could comprise means for storing energy generated during the generator operation of the motor (6), so that during the motor operation of the motor (6), the motor (6) is driven by means of the stored energy.

(18) Preferably, the yarn tensioning systems (1) also comprise a tension measuring device (not shown) for measuring the yarn tension. This measured yarn tension is then communicated to actuating means for actuating the motor (6), preferably by means of communication means, so that this motor (6) can be actuated on the basis thereof. In addition, the yarn tensioning systems (1) may comprise indicating means for generating a signal with regard to the measured yarn tension and communication means for communicating the measured yarn tension of the tension measuring device to these indicating means.

(19) By means of the speed of the motor (6) and the diameter of the brake roller (5), the length of the yarn (2) which is taken off by the yarn take-off system (4) can be easily determined.