Opening arrangement for an open-end spinning frame

Details Opening arrangement for an open-end spinning frame Opening arrangement for an open-end spinning frame

2002-08-27

2004-11-23

Calvert, John J. (Department: 3765)

Textiles: spinning, twisting, and twining

Apparatus and processes

Open end spinning

C057S408000

Reexamination Certificate

active

06820407

ABSTRACT:

CROSS-REFERENCES TO RELATED APPLICATIONS
This application claims the benefit of German Patent Application DE 10142488.4, filed Aug. 30, 2001, herein incorporated by reference.
FIELD OF THE INVENTION
The present invention relates to an opening arrangement for an open-end spinning device, in particular to an opening arrangement having a rotating opening roller having opening elements stationarily arranged on the circumference for opening a delivered sliver into individual fibers and for combing the fibers at a comb-out point.
BACKGROUND OF THE INVENTION
In connection with open-end spinning processes, such as during friction spinning, as well as in connection with the rotor spinning process, fibers delivered into the spinning process are separated into individual fibers by means of an opening roller. In order to prevent the compression of fibers, it is customarily desired that the fiber material be constantly accelerated during its entire travel from the feeding device of the opening roller to the yarn withdrawal device, so that the fibers are maintained in a stretched state and are not compressed. In the course of this, the withdrawal speed should not become too great. As a result of this, the circumferential speed of the opening roller is limited, since it must be lower than the yarn withdrawal speed. The permissible number of revolutions of such an opening roller is clearly lower than the number of revolutions of an opening roller that is employed during the customary open-end rotor spinning process. The high circumferential speeds of the opening roller in rotor spinning contribute to the prevention of an uneven opening of the delivered fibers and an increased separation of fiber bunches which are not, or only incompletely opened. While in rotor spinning the opening roller customarily runs at a speed of approximately 8000 rpm, the number of revolutions of the opening roller in friction or air spinning, for example, is only 1800 rpm because of the above mentioned conditions. At such low numbers of revolutions of the opening roller the occurring centrifugal forces are reduced to such an extent that the detaching of the fibers from the opening roller is only insufficiently aided by the centrifugal forces. The transfer of fibers from the opening roller to the respective collecting device, for example a suction roller with a perforated surface, is correspondingly inadequate. To lessen the effects of this disadvantage at least somewhat, opening rollers are employed whose combing, or opening elements consist, for example, of needles which are not inclined in the running direction of the opening roller.
Customarily, opening elements of opening rollers are inclined at an angle of 15 to 20 degrees in the running direction of the opening roller in order to further the draw-in of the fibers and their combing-out of the free end of the delivered fibers, the so-called fiber tuft. The edge of the opening element that is in front in the running direction is called tooth face in connection with sets of saw-teeth, whose inclination in the running direction is called a positive face angle. However, a positive face angle makes the removal of the fibers from the opening roller more difficult.
Although the opening and transfer of delivered fibers which, for example, consist of 100% cotton, is possible with needles which have no inclination, the quality of the combing-out process suffers considerably from the omission of the inclination.
However, such measures are insufficient for the satisfactory opening and transfer to the collecting member of delivered fibers consisting of a mixture of polyester and cotton. After a short time, often after only a few seconds, the fibers begin to wind around the opening roller and the opening process is hampered in a sustained manner or even stopped.
A needle roller, between whose needles bendable rods have been placed, for feeding a sliver to the combing element of an open-end spinning device is known from German Patent Publication DE-AS 24 18 516. The rods are intended to replace an elastic cover of a known device in which the needles are embedded up to their tips, and to prevent the formation of a winding on the needle roller. The rods extend between two supports arranged on the two front faces of the roller and permit the compression, or concentration, of the fiber at the places where it rests against the rods. The sliver is pressed against the feed table by the rods. In order to exert this pressure, it is necessary for the sliver to be so compact and thick that it deflects the rods out of their position of rest. Thus, the employment of the bendable rods is limited to the feed device of an opening arrangement.
Swiss Patent Publication CH-PS 620 949 discloses a feed roller for a combing cylinder, which has needles conducted in radial bores of the feed roller surface. The needles are moved between a withdrawal and a push-out position. Hence, it is intended to improve the opening of the fibers between the feed roller and the combing roller. An arrangement with movable needles is mechanically complex and open to malfunctions. Due to the movement of the needles inward in a radial direction, fibers are pulled along into the gap between the needle and the roller surface and collect there. In the course of the subsequent extension of the needles, the fibers can become stuck in the radial bore and can block the needle by means of a wedge effect. The use of saw-teeth in place of needles is not possible here. Such arrangements have not been accepted.
With opening rollers rotating at a number of revolutions which is multiple times greater than the number of revolutions of a draw-in roller, additional air flows are created in order to affect the fiber conveyance and the opening process.
German Patent Publication DE 196 08 828 A1 shows an opening roller which is provided with openings for generating radial airflow at the circumference. The opening roller is equipped with a set of teeth.
However, the generation of airflow entails additional compressed air consumption at each spinning position, which represents a considerable cost factor in connection with spinning arrangements with a plurality of spinning positions. A further disadvantage when employing airflow is caused in that the speed of the airflow that exits from such a perforated roller is greater than the speed of a fiber just separated from the rollers. Due to this, the airflow blows against the fiber end and the fiber is compressed in an undesirable manner.
German Patent Publication DE 198 50 518 A1, which defines the species, shows an opening roller which, together with a support roller, combs out the fiber tuft. Additional compressed air consumption can be avoided for this reason. Although the opening of slivers is improved, the problem of the winding of fibers, or of an unsatisfactory transfer of the fibers from the opening roller to the collecting member, is not solved.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to improve the function of the opening roller.
According to the present invention, this object is addressed by means of an opening arrangement for an open-end spinning device having a rotating opening roller with opening elements stationarily arranged on its circumference for opening a delivered sliver into individual fibers and for combing the fibers at a comb-out point, the rotating opening roller having a mechanical stripping arrangement that rotates along with the rotating opening roller.
It is possible with the opening roller of the present invention to lift fibers that, depending on the type of the opening element used, have been taken along by individual needles or teeth, in the area of the collecting member and to remove them from the opening elements, or from the set of teeth. The transfer of fibers from the opening roller to the collecting member is considerably improved. The extent of this improvement even permits the employment of needles or teeth of the opening roller having a positive face angle in order to perform better combing, without the fiber transf

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