Technical field

The present invention relates to a method of compensating for the difference between the drawing-off speed and the winding speed of yarn during the winding of yarn on a cross-wound bobbin at a workstation of a textile machine for producing yarn.

In addition, the invention relates to a workstation of a textile machine for producing yarn adapted to perform this method. Background art

During the winding of spun yarn on a cross-wound bobbin at a workstation of a textile machine for producing yarn, e.g., a rotor or air-jet spinning machine, etc., due to the difference between the drawing-off speed and the winding speed of yarn caused by traversing the spun yarn across the entire bobbin width and/or caused by different diameters of the ends of the conical bobbin, the yarn is periodically slackened and a yarn loop is formed, which worsens the quality of the created package and negatively affects its structure. To obtain a high-quality package, it is necessary to compensate for the yarn slackening and obtain stable yarn tension. Various types of compensators are used for this purpose, whereby these compensators comprise a compensating arm acting on the yarn with its end and deflecting it from a straight path during its movement, thereby lengthening or shortening in the required manner its working path between a draw-off mechanism and a winding device. The disadvantage of the existing methods of compensating for the difference the drawing-off speed and the winding speed of yarn is the fact that the arms of the compensators move perpendicularly or substantially perpendicularly to the direction of the yarn withdrawal from the spinning unit (and thus also to the preferred direction of the yarn movement between the draw-off mechanism and the winding device - see Fig. 1), as a result of which the deflected yarn wraps around a large part of the circumference of a guide element/guide elements arranged between the draw-off mechanism and the winding device of the workstation. Due to this, there is a relatively high friction between the yarn and the surface of the guide element(s), which increases the risk of mechanical damage to the yarn. Furthermore, this significantly increases demands on the drive of the winding device. The object of the invention is therefore to provide a method of compensating for the difference the drawing-off speed and the winding speed of yarn during the winding of yarn on a bobbin at a workstation of a textile machine for producing yarn, which would eliminate the disadvantages of the background art. In addition, the object of the invention is to propose a workstation of a textile machine for producing yarn adapted to perform this method.

Principle of the invention

The object of the present invention is achieved by a method of compensating for the difference the drawing-off speed and the winding speed of yarn during the winding of yarn on a cross-wound bobbin at a workstation of a textile machine for producing yarn, in which in the space between a draw-off mechanism of yarn and a winding device of yarn on a bobbin, the yarn is in case of need deflected from its straight path by the action of a compensating arm of a compensator of the difference of the drawing-off speed and the winding speed of yarn, whereby the compensating arm moves between its front working position, in which it does not deflect the yarn from its straight line path or deflects it only minimally, and its rear working position, in which it deflects the yarn from its straight line the most, by which means a compensation loop of yarn is created repeatedly, whose principle consists in that the yarn is deflected in such a manner that the axis of the compensation loop of yarn is parallel with the direction of yarn withdrawal by the draw-off mechanism of yarn or forms an angle a of a maximum of 60°, preferably a maximum of 45°, with the direction of the yarn withdrawal by the draw-off mechanism. As a result, the yarn even at the maximum deflection of the compensating arm or when the maximum compensation loop is formed, touches the surface of the next guide element/elements only tangentially or wraps around only a very small part of its/their surface, due to which the overall friction substantially decreases.

In a preferred variant, the yarn is deflected such that the compensating arm during its movement between its front and rear working positions intersects a plane which is interspersed with the axes of the draw-off rollers of the draw-off mechanism. The compensating arm of the compensator performs a rectilinear or curvilinear movement between its front working position and its rear working position.

Furthermore, the object of the present invention is achieved by a workstation of a textile machine for producing yarn which in the space between its draw-off mechanism of yarn and winding device of yarn on a bobbin comprises a compensator of the difference between the drawing-off speed of yarn and the winding speed of yarn on a bobbin, whereby this compensator comprises a compensating arm mounted reversibly displacingly between its front working position, in which it does not deflect the yarn from the straight line path or deflects it only minimally, and its rear working position, in which it deflects the yarn from its straight line path the most, whose principle consists in that the front working position of the compensating arm and the rear working position of the compensating arm are arranged on a straight line which is parallel with the direction of the yarn withdrawal by the draw-off mechanism or which forms an angle a of a maximum of 60°, preferably a maximum of 45°, with the direction of the yarn withdrawal by the draw-off mechanism.

In a preferred variant of embodiment, this straight line intersects a plane interspersed with the longitudinal axes of the draw-off rollers of the draw-off mechanism. The compensating arm of the compensator can be arranged between its front working position and its rear working position displaceably as required along a straight or curvilinear trajectory. Description of the drawings

In an enclosed drawing, Fig. 1 schematically represents a part of a workstation of a textile machine for producing yarn with an existing conventional arrangement and path of a compensating arm of a compensator of the difference between the drawing-off speed and the winding speed of yarn between a draw-off mechanism and a winding device of this workstation. Fig. 2 schematically shows a part of the workstation of the textile machine for producing yarn with the compensating arm of the compensator of the difference between the drawing-off speed and the winding speed of yarn arranged between the draw-off mechanism and the winding device of the workstation for compensating for the difference between these speeds by the method according to the invention. Fig. 3 schematically shows a part of the workstation of the textile machine for producing yarn with a different arrangement of the compensating arm of the compensator of the difference between the drawing- off speed and the winding speed of yarn arranged between the draw-off mechanism and the winding device of the workstation for compensating for the difference between these speeds by the method according to the invention.

Exemplary embodiments of the invention The present invention will be hereinafter described with reference to an embodiment of an existing workstation of a textile machine for producing yarn shown in Fig. 1 and the function of its elements, and with reference to two exemplary embodiments of a workstation of a textile machine for producing yarn adapted to compensate for the difference the drawing-off speed and the winding speed of yarn during the winding of yarn on a bobbin according to the invention shown in Figs. 2 and 3 and function of their elements. The exemplary embodiments of a workstation of a textile machine have a vertical arrangement, but the principle of the invention can be applied analogously also to other arrangements of a workstation of a textile machine. A workstation of a textile machine for producing yarn is in principle well- known, and therefore only those parts and nodes thereof which are important for the present invention will be described in more detail hereinafter. Each workstation comprises a spinning unit 1 with an unillustrated spinning rotor or a spinning nozzle. In this spinning unit 1, yarn 2 is formed by spinning fibrous material. A draw-off mechanism 3 is arranged behind the spinning unit 1. (in the direction of the yarn movement 2). The draw-off mechanism 3 comprises a pair of draw-off rollers 31, 22 which are rotatably mounted in the machine structure (see arrow A). One of the draw-off rollers 31, 32 is coupled to an unillustrated drive and constitutes a driven draw-off roller 31, 32; the other draw-off roller 31, 32 is mounted on an unillustrated tilting spring arm and constitutes a pressure draw-off roller 31, 32. Both the draw-off rollers 31, 32 lie on top of each other during the production of the yarn 2, whereby a compression line is formed at the point of their contact, through which passes the yarn 2 which is thus drawn off from the spinning unit 1 by the rotation of the draw-off rollers 31, 32. Behind the draw-off mechanism 3 is arranged a winding device 4 for winding the yarn 2 on a cross-wound bobbin 41. The winding device 4 of yarn 2 may comprise unillustrated tilting winding arms of any of known constructions which are adapted to mount a tube for winding the yarn 2. In doing so, the bobbin 41 being wound abuts the surface of a drive cylinder 42 which is coupled to an unillustrated drive and which drives the bobbin 41 (see arrow B), whereby the bobbin 41 can be pressed against it in addition to its weight by an unillustrated pressure means - e.g., by a spring or a magnet, etc. In addition, the winding device 4 comprises an unillustrated traversing device which traverses the wound yarn 2 in a required manner across the entire length of the bobbin 41.

If necessary, further elements are arranged between the draw-off mechanism 3 and the winding device 4, such as an inlet of an unillustrated (vacuum) temporary storage device of yarn 2 to form a yarn 2 reserve for spinning-in, a yarn 2 sensor 5 - for example, a sensor of the presence and/or the quality of yarn 2, a paraffining unit 6 for paraffining the wound yarn 2 and for reducing friction when the yarn is guided by the yarn guide elements 2 of the workstation and when it is further processed, etc.

Between the draw-off mechanism 3 and the winding device 4, in the path of yarn 2, is arranged a compensator of the difference between the draw-off and winding speeds of yarn 2, whose compensating arm 7 _j coupled to an unillustrated drive, is arranged reversibly displaceably between at least two working positions (see arrow C), whereby during the movement between these working positions, the compensating arm 7 intersects the path of yarn 2 - in the embodiment according to the background art shown in Fig. 1 , the compensating arm 7 of the compensator moves between its front working position (marked with dots), in which it does not deflect the yarn 2 or deflects it only minimally, and its rear working position, in which it deflects the yarn 2 from its straight line path and forms a compensation loop 8 of yarn 2. The straight line T\_ (which usually also corresponds to the trajectory of the compensating arm 7), on which the two working positions of the compensating arm 7 are situated, is perpendicular to the direction of the yarn withdrawal by the draw-off mechanism 3 from the spinning unit 1 and the whole straight line 7 is located (in the direction of the yarn 2 movement) behind the plane R interspersed with the axes of the draw-off rollers 31, 32. With this arrangement, the yarn when forming the compensation loop 8 _j wraps around a large part of the surface of the guide element/elements 9 of yarn 2 arranged behind the winding device 4 - see Fig. 1.

At the workstation of a textile machine for producing yarn 2, adapted to perform the method of compensating for the difference the drawing-off speed and the winding speed of yarn 2 according to the invention, the compensating arm 7 of the compensator of the difference the drawing-off speed and the winding speed of yarn 2 is arranged reversibly displaceably between at least two working positions which are arranged on the straight line 7 , which is parallel or substantially parallel with the direction of the yarn 2 withdrawal by the draw-off mechanism 3 from the spinning unit 1 (Fig. 2) or on the straight line 71 which forms an angle g of a maximum of 60°, preferably of a maximum of 45°, with the direction of the yarn withdrawal by the draw-off mechanism 3 from the spinning unit 1 (Fig. 3). In the front working position (marked with dots), the compensating arm 7 of the compensator does not deflect the yarn 2 or deflects it only minimally, and in the rear working position it deflects it from its straight- line path and forms a compensation loop 8 on it. The axis of the compensation loop 8 is parallel or substantially parallel with the direction of the yarn 2 withdrawal by the draw-off mechanism 3 from the spinning unit 1 (Fig. 2) or forms with this direction an angle g of a maximum of 60°, preferably a maximum of 45° (Fig. 3). In the embodiment shown in Figs. 2 and 3, at least one of the working positions of the compensating arm 7 is situated on the opposite side of the plane R interspersed with the axes of the draw-off rollers 31, 32 of the draw off mechanism 3, than the winding device 4 of yarn 2, however, in another way of guiding the yarn 2 in the space between the draw-off mechanism 3 and the winding device 4, e.g., when inserting a rotated guide element, it is possible for the two positions of the arm 7 of the compensator to be situated on the same side of the plane R interspersed with the axes of the draw-off rollers 31, 32 of the draw-off mechanism 3 as the winding device 4. With this arrangement, the yarn 2 even at the maximum deflection or when the maximum compensation loop 8 is formed, touches the surface of the next guide element/elements 9 only tangentially (Fig. 2) or wraps around only a very small part of its/their surface (Fig. 3). As a result, there is a significant reduction in friction and thus also in the risk of mechanical damage to the yarn 2. The increased angle of wrapping of the guide roller 32 does not increase the overall friction in any way due to the rotation of this roller 32.

The compensating arm 7 of the compensator moves between its working positions preferably in a straight line, e.g., along a vertical trajectory (Fig. 2), but, e.g., for design reasons, it can also move between them in a curvilinear manner, e.g., along a rounded trajectory, etc. In case of need, the compensating arm 7 may be mounted in the structure of a textile machine controllably, with the possibility of moving between more working positions in different phases of operation of the workstation, than only between its upper and lower working positions, possibly also with the possibility of moving outside this working range.

List of references

1 spinning unit

2 yarn

3 draw-off mechanism 31 draw-off roller

32 draw-off roller

4 winding device

41 bobbin

42 drive cylinder 5 yarn sensor

6 paraffining unit

7 compensating arm of the compensator

71 straight line on which both working positions of the compensating arm lie

8 compensation loop of yarn 9 yarn guide element a angle between the straight line 71 and the direction of yarn withdrawal from the spinning unit

R plane interspersed with the axes of the draw-off rollers