Textiles: spinning – twisting – and twining – Apparatus and processes – Open end spinning
Reexamination Certificate
2000-10-02
2001-09-25
Worrell, Danny (Department: 3741)
Textiles: spinning, twisting, and twining
Apparatus and processes
Open end spinning
C057S404000, C057S416000
Reexamination Certificate
active
06293083
ABSTRACT:
CROSS-REFERENCES TO RELATED APPLICATIONS
This application claims the benefit of German patent application 19947547.4 filed Oct. 2, 1999, herein incorporated by reference.
FIELD OF THE INVENTION
The present invention relates to a spinning rotor for an open-end spinning frame and, more particularly, to such a spinning rotor wherein at least those surfaces which come into contact with the textile fibers being spun or the resultant spun yarn have an applied coating of a non-ferrous metal with hard material granules embedded therein.
BACKGROUND OF THE INVENTION
Spinning rotors are subject to extensive wear of the surfaces which come into contact with the textile fibers being spun or the resultant spun yarn. It is known to apply a coating having hard material granules embedded therein to the surface of the spinning rotor to increase the wear resistance of the rotor surface. A representative form of such a coating is a nickel-diamond coating, for example. It is intended to also achieve a good spinning performance of the spinning rotor by means of the nickel-diamond coating, besides good wear properties.
Coatings with embedded hard material granules are known in a variety of embodiments. German Patent Publication DE 197 13 359 A1, for example, describes a spinning rotor with a rotor cup, whose inner surface has a nickel dispersion layer of uniform layer thickness, wherein the concentration of the hard material granules embedded in the nickel dispersion layer is clearly less on the fiber slide face in the area of the surface of the nickel dispersion layer than in the rotor groove.
With the spinning rotor for open-end spinning units represented in German Patent Publication DE 198 25 906 A1, the fiber collection groove is provided with a nickel-diamond coating, and the fiber slide face with a coating of pure nickel. The coatings are applied in separate coating operations and separate baths. In the course of this coating operation, the entire inner and outer contours of the rotor disk are initially provided with a nickel coating, although from the viewpoint of function it is only required on the fiber slide face. In this manner, the nickel coating provides corrosion protection of the remaining surfaces. The nickel-diamond coating is thereafter applied to the nickel coating only in the fiber collection groove.
German Patent Publication DE 198 22 265 A1discloses an open-end spinning rotor with a fiber slide face provided with a nickel-diamond coating. This nickel-diamond coating consists of an inner support layer and an outer working layer. In this case, the diamond granules embedded in the inner support layer are larger than the diamond granules embedded in the outer working layer. The support layer and the working layer are interlocked.
In addition to the wear caused by the fiber material, the surface at the interior of the spinning rotor can be subjected to mechanical, intermittently occurring stress during the cleaning process. Cleaning of the rotor interior is performed in case of a malfunction report triggered by soiling of the spinning rotor, or as a part of the piecing process. Various processes for cleaning rotors are known. The rotor surface is stressed to a greater or lesser degree, depending on the intensity of cleaning. Since normally the complete cleaning of the spinning rotor is desired, intensive cleaning processes are preferred. In many cases, blowing compressed air through the spinning rotor is not sufficient by itself, since shell particles can become jammed in the narrow rotor grooves. Dependable cleaning is assured if the spinning box is flipped open and the spinning rotor is worked by means of suitable instruments. In the course of a customary intensive cleaning process to remove or avoid the interference with the spinning quality or with piecing, the dirt on the inside of the spinning rotor, in particular in the rotor groove, is loosened by means of a scraper and removed from the rotor by compressed air. The scraper customarily also consists of a wear- resistant material, for example fiberglass-reinforced plastic or hardened material, such as steel. Pieces can be broken out of the above-described rotor coating because of the stress which is exerted by the scraper on the coated surface. Breaking or flaking off of the coating occurs in an uncontrolled manner. The separated pieces can be large enough so that the base material of the spinning rotor is exposed. As a result, the wear protection by means of the nickel-diamond coating is completely interrupted in places. These places can promote the breaking off of further adjoining pieces of the known coating down to the base material.
Flaking or breaking off of pieces of the coating can also be triggered by the oscillations occurring at the rotor.
Pieces of the coating used for wear protection down to the base material can flake off from all known nickel-diamond coatings. The service life of the spinning rotor is clearly reduced by this damage.
OBJECT AND SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to maintain protection against wear of the rotor surface, even when pieces of the coating thereon have flaked off or been broken or otherwise removed or damaged, by means of a coating with hard material granules embedded therein on the damaged area of the surface.
This object is attained in accordance with the present invention by providing a spinning rotor with a coating of at least two layers containing hard material granules, between which there is an intermediate layer which is essentially free of hard material granules. With such an embodiment of protective coating, it is possible to prevent the wear protection achieved by means of the coating containing hard material granules from being completely removed in places because of the removal of a piece of the coating.
It has been shown that, with the embodiment of a protective coating in accordance with the present invention, only portions of the uppermost layer containing hard material granules are separated when pieces of the coating are broken or flake off, and the layer containing hard material granules following under the respective intermediate layer is preserved and maintains the wear protection.
To assure sufficient wear protection, the layers containing hard material granules are advantageously at least about 10 &mgr;m thick. The layers free of hard material granules are preferably between about 2 &mgr;m and about 10 &mgr;m thick. Such a layer thickness of the intermediate layer has been shown to be particularly advantageous in the event any flaking off of the coating occurs. While such flaking or other separation of the coating is still undesirable with coatings in accordance with the present invention, the flaking-off process is better controlled in that the breaking or flaking off of a piece of the coating is essentially limited to the uppermost layer containing hard material granules.
The non-ferrous material is hardenable, preferably for example nickel, and the hard material granules preferably are diamond granules, which embodiments result in good wear properties, in particular of the layers with hard material granules embedded therein. Advantageously, the coating of the non-ferrous material and the hard material granules is precipitated in a single nickel dispersion bath, in which the concentration of the hard material granules distributed therein can be preprogrammed. The manufacture of spinning rotors in accordance with the invention can thereby take place without interruption and cost-effectively. It is further preferred that the spinning rotor has been subjected to a heating process prior to the coating application of the present invention for increasing its hardness.
After the application of several layers, no increase in flaking off of the coating was noted. Instead, when employing a coating in accordance with the present invention, it is possible to avoid any significant reduction of the service life of a coated spinning rotor following the breaking or flaking off of pieces of the coating with embedded hard material gran
Kennedy Covington Lobdell & Hickman LLP
W. Schlafhorst AG & Co.
Worrell Danny
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