HK1017911B - Device for producing a leno selvedge, particular for shuttleless looms - Google Patents

Description

Device for forming leno selvedge, in particular for weaving looms

The invention relates to a device for forming leno selvedges, in particular for weaving looms, comprising an electric motor with a rotor, wherein the rotor has at least two warp guide elements at a distance from one another.

From FR-a 2390524 a leno selvedge forming apparatus is known in which the swivel arms are elastically retractable in the axial direction. This device is a so-called "planetary gear mechanism". The planetary twisting device has a considerable mass due to its construction, and in the known planetary twisting device the skein packages are also mounted directly on the twisting device. That is to say, such a device has such a large mass that it is physically impossible to accelerate and brake it at all within a short time interval.

The same is valid for DE-a 1535579, which also describes a so-called planetary twisting device. Such devices also cannot accelerate and brake quickly based on their inertial mass. Also US-a2,918,092 has no other effect because its device also moves with the package.

A device of the type mentioned at the outset is known from DE-PS 4405776. An electrically controlled servomotor is provided which drives a reel, wherein the reel forms the rotor of the electrically controlled servomotor. The stator itself can be mounted on the weaving machine by means of a bracket and preferably in a free space between the longitudinal support and the heddle wire and in front of the first heddle frame of the weaving machine. In this case, it can be seen in detail that the reel wheel, which forms the rotor of the electronically controlled servomotor, as a guide element has two openings arranged opposite one another, through which the respective leno warp thread passes. Known rotary selvedge leno devices on such weaving machines work in such a way that they rotate several hundred revolutions in one direction and after each revolution are lenked with a weft thread. Thereby forming an all-twisted leno selvedge. On the feed side of the two strands, the strands themselves twist in accordance with the number of revolutions of the wheel, and therefore, to eliminate this twisting, the direction of rotation is changed, so that the wheel must rotate in the diametrically opposite direction. In this case, the number of revolutions in each direction must be the same within the time frame of averaging. If the direction of rotation is not changed, the tension increases as the twist increases gradually, and the warp may break at any time. The result calculated in known high speed machines up to 1200 picks per minute is that the direction of rotation should be changed after approximately 100 to 1000 revolutions in one direction. That is, according to the prior art, the direction of rotation of the rotor of the electrically controlled servomotor, i.e. the direction of rotation of the reel, must be changed every 10 to 100 seconds. For this purpose, the maximum time available is 100 milliseconds, based on the stroke value of the weaving machine. That is, the rotor of the motor must stop and rotate at full speed in the exact opposite direction of rotation within 100 milliseconds. However, such operation cannot be achieved with the known electric motor because of the large mass of the sheave or rotor. It is therefore natural to think of reducing the inertial mass of the motor by choosing a motor that is overall smaller. However, this involves the risk that, when the diameter of the rotor, i.e. the capstan, is small, only a small shed can be formed between the two warps guided by the capstan, which has the disadvantage that the weft thread cannot be guided in a neat manner. Furthermore, the yarns may stick to each other, and the selvedges produced are therefore not neat.

Furthermore, there is the problem that the yarn tension of the skein guided by the guide element varies during the rotation of the guide element. The variation depends on the length of the yarn of the skein, which in turn depends on the angle of rotation and the angular position of the device with respect to the loom. In the case of sensitive yarns, there is a risk of breakage of said yarns due to variations in the tension of the yarns.

The object of the invention is therefore to improve a device of the type mentioned at the beginning in such a way that it has little mass on the one hand, so that a fully leno selvedge can be produced neatly even in the case of high-speed weaving machines, and also in such a way that it can compensate for variations in the tension of the leno warp in order to avoid yarn breaks.

The object of the invention is achieved in that the guide element is formed by a pivoted arm which is elastically retractable in the axial direction of the motor and which has at its end a loop through which the skein passes, in order to compensate for the thread tension.

By means of the elastic structure of the guide element in the axial direction of the rotor and the corresponding bending of the guide element, it is possible to compensate for the otherwise occurring changes in the tension of the skein yarn.

It can be seen that the motor rotor can be reversed in its direction of rotation in order to eliminate twisting of the skein.

Advantageously, said elastically retracting tumbler is provided at its end with a loop through which the skein passes. The arm itself is light because it has substantially no load. Thus, its mass is relatively negligible. That is, a small motor with a rather small rotor can be selected, and thus the mass of the motor is also rather small, and due to the arrangement based on the mounting of the rotor arms on the rotor, the designer is free to choose the size and diameter of the motor, apart from the power requirements. It is thus also possible to use motors with a small diameter and a comparatively small inertial mass without the risk of not being able to form the shed height neatly. Because of the variability in the length of the rotating arms mounted on the rotor, the spacing of the loops on the rotating arms and the size of the shed height can be selected substantially freely. In this regard, there is also the possibility of eliminating the twisting phenomenon of the skein, i.e. letting the rotor change its direction of rotation.

Said arms are placed on the rotor substantially perpendicular to the axis of rotation of the rotor and thus radially, similar to the wings of the propeller. In order to ensure that the pivoted arms, which are related to the position of the heald frames of the weaving machine, are always in the optimum position set by the control mechanism of the device, the pivoted arms are arranged to be rigid in the tangential direction.

According to a preferred feature of the invention the rotor advantageously has a central bore in the region of its axis of rotation through which the skein passes. That is to say, the skein can traverse through an aperture arranged in the centre of the body of revolution, in particular taking into account the possible twisting phenomena in the region of this aperture of the rotor, which improves the guidance of the yarn.

In detail, said arms are arranged at the end of the rotor directed towards the fabric; the end of each pivot arm is preferably formed as a hook, and a loop for guiding the skein is provided in the region of the hook. The ring may be provided with inserts to reduce wear on the ring due to the guiding of the twisted threads; particularly preferred are sleeve-like inserts made of ceramic material.

According to another characteristic of the invention, the electric motor with rotor is arranged on the loom in such a way that the axis of rotation is either parallel to the warp threads or at an angle of up to 90 ° to the warp threads. In particular in the case of an angle of almost 90 °, the device is preferably arranged directly next to the selvedge, which also makes it possible to arrange the leno selvedge directly on the fabric end. According to a further feature of the invention, it may also be necessary to provide a further swivel arm on the opposite end of the rotor, parallel to the swivel arm provided on the end directed toward the fabric side. Said other tumbler is therefore required in order to ensure that the skein coming from the package is neatly twisted in the feed area. Thus, by changing the direction of rotation of the motor rotor, the formation of the twisted strands in the feed zone of the yarn coming from the package can be eliminated in the same way as it is twisted. The problem does not arise in this form when the axis of rotation of the rotor is arranged parallel to the warp threads of the weaving machine.

The invention is explained in detail below by way of example with the aid of the accompanying drawings.

Figure 1 shows a schematic view of the device according to the invention in a nearly perpendicular arrangement to the fabric, where the heald frames and reeds have been omitted for a better overview;

FIG. 2 shows a schematic view of the apparatus in a position where the axis of rotation of the rotor is parallel to the warp yarns;

FIG. 3 shows the motor with the rotor in a position at an angle of about 45 to the warp yarns;

FIG. 4 shows a schematic representation of the weave structure of an all-leno rib.

In the device 1 described in fig. 1 to 3, a motor, generally indicated at 10, is provided, which has a central hole 11 through which the sketches 20, 30 pass. In the case of the embodiment shown in fig. 1, two pairs of swivel arms 60, 70 are provided in pairs when the axis of rotation is perpendicular to the warp threads 40, i.e. substantially parallel to the weft threads 50. Each of the paired rotation arms 60, 70 is composed of two rotation arms 61, 62 or 71, 72. The two pairs of swivel arms are parallel to each other and are respectively fixed to the side ends of the rotor 10, as clearly seen in fig. 1. The end of the swivel arm 61, 62 or 71, 72 is hook-shaped and provided with a loop 73, 74 or 63, 64 in the region of the hook-shaped bend. These loops are intended to allow the passage of the skein 20, 30 coming off the bobbin 80, 90. Furthermore, the swivel arms 61, 62 or 71, 72 are elastically retractable in the axial direction (arrow 200) of the rotor of the motor 10, in order to be able to compensate for variations in the yarn tension.

During rotation of the arms 60, 70 in pairs, a fully leno selvedge 100 (fig. 4) is formed in the area of the fabric. The skein 20, 30 coming from the bobbin 80, 90 also produces a twist of the yarn in the feed zone (at 110), which is removed again by changing the direction of rotation of the rotor after a certain number of revolutions in one direction. The leno selvedge is prevented from being untwisted in this case by inserting weft threads 50 between the warp strands. That is, in the process of untwisting the twist 110, the selvedge is formed on the other fabric region by twisting with the corresponding weft yarn.

The device operates in such a way that the rotor of the electric motor is driven in such a way that its rotation is synchronized with the heald frame movement. Alternatively, advanced interlacing is achieved by corresponding synchronized phase traversals between rotor rotation and heald frame motion. That is to say that the operation of such a device is independent of the heald frame and in contrast to a selvedge machine mounted on a heald frame.

In the arrangement of the axes of rotation parallel to the warp threads 40 shown in figure 2, the heald frame is denoted 130 and the reed is denoted 140, although there are only minor problems in feeding the skeins 20, 30 to the device. In the rotor position shown in fig. 2, however, it is at a considerable distance from the fabric, so that the leno selvedge is not formed directly on the fabric.

When the device is in the position shown in figure 3, the selvage is clearly adjacent to the fabric. That is to say here the position of the device is about 45 deg. to the fabric. The thread guiding device 120 is however roller-type or roller-type in order to be able to introduce the thread onto the fabric in such a way that the shed height is neatly established.

The weave structure that can be made with this device (fig. 4) is called an all-leno selvedge, that is, the weave structure twists each weft yarn together. Such a selvedge is extremely stable despite only three yarns and, precisely because only three yarns are used, is of such a small thickness that the fabric does not bulge and also does not move in the edge region on the beam.

Claims (12)

1. A device for forming leno selvedges, in particular for weaving machines, comprising an electric motor (10) with a rotor, where said rotor has at least two guide elements for the leno warps (20, 30) at a distance from each other, characterized in that: the guide element is formed by a pivoted arm (61, 62; 71, 72) which is provided at its end with a loop (63, 64; 73, 74) through which the skein (20, 30) passes, wherein the pivoted arm (61, 62; 71, 72) is elastically retractable in the axial direction of the motor (10) in order to compensate for the thread tension.

2. The apparatus of claim 1, wherein: the swivel arms (61, 62; 71, 72) are arranged to be rigid in the tangential direction.

3. The apparatus of claim 1, wherein: the rotor of the electric motor (10) has a bore (11) in the region of its axis of rotation, through which the leno (20, 30) passes.

4. The apparatus of claim 1, wherein: the ends of the swivel arms (61, 62; 71, 72) are hook-shaped, and loops (63, 64; 73, 74) are provided in the hook-shaped bending regions.

5. The apparatus of claim 1, wherein: said arms (61, 62; 71, 72) are arranged at the end of the rotor of the motor (10) directed towards the fabric side.

6. The apparatus of claim 1, wherein: on the end of the opposite side, a further pivot arm (71, 72) is arranged, which is parallel to the pivot arm (61, 62) arranged on the end directed to the fabric side.

7. The apparatus of claim 1, wherein: the electric motor (10) with rotor is arranged on the loom in such a way that the axis of rotation is parallel to or at an angle of up to 90 DEG to the warp threads (40).

8. The apparatus of claim 1, wherein: the arms (61, 62; 71, 72) are mounted on the rotor of the motor (10) so as to be radially adjustable.

9. The apparatus of claim 1, wherein: the arm length of the swivel arm (61, 62; 71, 72) can be varied.

10. The apparatus of claim 1, wherein: a hole (11) through which the skein (20, 30) passes is arranged in the centre of the rotor.

11. The apparatus of claim 1, wherein: the arms (61, 62; 71, 72) are arranged on the rotor perpendicularly to the axis of rotation of the rotor of the electric motor (10).

12. The apparatus of claim 1, wherein: the rotor of the motor (10) can change its direction of rotation.