Textiles: spinning – twisting – and twining – Apparatus and processes – Open end spinning
Reexamination Certificate
2000-03-09
2001-11-27
Calvert, John J. (Department: 3765)
Textiles: spinning, twisting, and twining
Apparatus and processes
Open end spinning
C057S404000, C057S408000, C057S411000, C057S413000, C057S414000, C057S416000, C057S417000, C057S415000, C057S407000
Reexamination Certificate
active
06321522
ABSTRACT:
CROSS-REFERENCES TO RELATED APPLICATIONS
This application claims the benefit of German patent application DE19910276.7, filed Mar. 9, 1999, herein incorporated by reference.
FIELD OF THE INVENTION
The present invention relates to a spinning rotor for open-end spinning machines, wherein the rotor has a rotor cup with a collar and is suitable for a high number of rotor revolutions, and relates further to a method for producing such a spinning rotor.
BACKGROUND OF THE INVENTION
With rapidly rotating bodies, for example spinning rotors, an imbalance occurs when the mass of the body is distributed in such a way that the center of gravity lies outside of the axis of rotation, or if the axis of rotation and the axis of inertia are not coincident. The imbalance results in undesired reaction forces during the rotation of the body causing uneven running or vibrations, which in particular increase considerably as rotational speed increases and/or in certain frequency ranges. Undesired results can occur, for example, loud noises, malfunctions, wear or even destruction of the rotor, which require maintenance or the replacement of such unbalanced components. Expense and downtime are created because of maintenance and replacement work, and the efficiency and/or the productivity, of the machine is negatively affected.
To prevent such disadvantages, dynamic balancing is customarily performed as a portion of the production process of such rapidly rotating bodies. In some cases, the mass equalization of the body can be accomplished by the installation of weights or in most cases by the removal of material from the body.
Presently the operating speed of spinning rotors in open-end spinning machines already is greater than 100,000 rpm. With such high numbers of revolution, the bearings and drive mechanisms of the spinning rotors are exposed to enormous stresses, together with the above described disadvantages, even in cases of small imbalances. It is therefore well known that it is imperative to not only produce spinning rotors with the highest precision in shape, but also to balance them carefully. In accordance with the known prior art, the balancing the spinning rotors by the removal of material is accomplished by grinding its exterior circumference. Grinding is customarily performed on the rotor cup at the end edge of the collar and at the exterior circumference at the location of its greatest circumference. Balancing of this type is known, for example, from European Patent Document EP 0 099 490 B1, as well as German Patent Publication DE 43 12 365 A1.
Balancing, already described as the prior art in European Patent Document EP 0 099 490 B1, is performed by grinding the exterior circumference of the spinning rotor. Although the removal of material as described in this reference has a considerable effect, the relatively thin wall of open-end spinning rotors, particularly in those rotors formed by a non-cutting formation process, is weakened at a critical point. In European Patent Document EP 0 099 490 B1 it is already expressly pointed out that such weakening must be absolutely avoided in view of the high number of rotor revolutions which is customary today. A balancing method is therefore disclosed in this reference wherein a first production step accomplishes mass equalization by initially punching a hole through the bottom of the rotor cup in the course of the compression process, and thereafter the hole may be enlarged to a degree sufficient for mass equalization. Such method, however, is expensive, time-consuming and, in particular, is limited to spinning rotors made by plastic deformation, for example from sheet metal.
German Patent Publication DE 43 12 365 A1 describes a rotor balancing method by grinding of the rotor collar. However, the considerable outlay required in the course of such balancing is disadvantageous.
German Patent Publication DE 43 39 064 A1 discloses a balancing method wherein balancing is performed by means of a pulsating laser beam. The pulse frequency of the laser beam is synchronized with the rotating speed of the rotor within an imbalance measuring device during the balancing process, such that the laser removes material when the unbalanced portion of the rotor turns past the impact point of the laser on the surface of the rotor. However, this method does not operate with sufficient precision for the exact balancing necessary to meet the desired quality requirements to balance the body for operation at high numbers of revolution. The exact guidance of the rotor during the rotating movement in the course of the balancing process is an absolute prerequisite for precise balancing by means of such a method, but is either too inaccurate or extraordinarily elaborate and therefore too expensive.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to achieve further improvements in regard to the balancing of open-end spinning rotors.
In accordance with the invention, this object is attained by a spinning rotor basically comprising a rotor cup with a collar. The spinning rotor is made suitable for operation at a high number of rotor revolutions in an open-end spinning machine by the formation thereon of at least one identification mark created by the removal of material from a selected exterior surface of the rotor cup or the collar, the identification mark being formed at a selected position on the exterior surface and to a selected removal depth for mass equalization of the spinning rotor.
Such a spinning rotor in accordance with the present invention is distinguished by good balancing qualities. The identification mark is accomplished by a precisely metered removal of material. The increased balancing quality leads to quieter running and thus can improve the functional properties of the spinning rotor, in particular the operational dependability of the spinning rotor, and therefore the productivity of the spinning station. The spinning rotor in accordance with the invention does not require any additional removal of material besides the identification mark, such as an interfering notch or cutout, for example, which can lead to undesired and disadvantageous interference with the boundary layer flow or to an impermissible weakening of the stability of the spinning rotor. It is possible to keep the removal depth extremely slight by distributing the material removal over the entire surface of the identification mark, and it therefore has an advantageous effect on the surrounding airflow at high numbers of revolutions of the spinning rotor. A flow-efficient spinning rotor in accordance with the invention reduces energy consumption, particularly at such high numbers of revolutions, is cost-effective because of the reduction of outlay and time during its production, and in this manner allows a considerable cost savings in connection with the customary design of the open-end spinning machines with a plurality of spinning stations.
The identification mark produced by the removal of material is essentially permanent and easily recognizable. It can be used for identification and/or information. For this purpose the identification mark preferably consists of lettering or a graphic symbol, or alternatively a combination of lettering and a graphic symbol.
Advantageously the identification mark is arranged on the exterior circumference of the collar of the spinning rotor, preferably on a cylinder-shaped section of the collar. At this location the material removal is very effective as a mass equalization, without negatively affecting the air resistance or the stability of the spinning rotor, such as otherwise occurs by the notching of the exterior radius of the largest diameter of the rotor cup in accordance with the prior art. It is thus possible to avoid the material removal at the exterior radius of the greatest diameter of the rotor cup, as well as at the edge of the collar toward the shaft, otherwise customary in the course of balancing methods of the prior art, by the effective positioning of the identification mark on the cylinder-shaped section of the
Bohne Ralf
Haaken Dieter
Landolt Claus-Dieter
Segura Fernando
Calvert John J.
Kennedy Covington Lobdell & Hickman LLP
Smith James G.
W. Schalfhorst AG & Co.
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