Abstract:
The invention is relative to opening devices for spinning machines, especially open-end spinning machines, that are provided with clothing wires or rings for separating fibers of a supplied sliver. The opening device is characterized in that the clothing wires are pre-bent in accordance with the geometry of a carrier ring, or the clothing rings have the desired geometry of the finished part, and that the particular workpiece surfaces have an at least two-coating construction in which an outer coating is a hard-substance coating. The hard-substance coating consists entirely or partially of especially hard hard-substance components and rests on a substrate layer located underneath it.

Description:
FIELD OF THE INVENTION 
   The present invention relates to an opening device for spinning machines, especially open-end spinning machines, that is provided with a clothing wire or opening ring for individualizing fibers of a supplied sliver. In addition, the invention relates to a method of producing such an opening device. 
   BACKGROUND 
   It is necessary in the manufacture of yarns in certain work steps to separate the fibers to be processed from each other, that is, to open their composition with each other. It is necessary, for example, in other manufacturing steps, to align fibers as parallel to each other as possible. This procedure is called parallelization. The fibers to be processed enter into a mechanical contact with the processing devices during opening as well as during the parallelization of the fibers. As a consequence of the mechanical contact, a mechanical wear occurs on the devices that is, on the one hand, disadvantageous for the service life of the devices and, on the other hand, for the quality of the produced products. Such wear phenomena are especially noticeable in opening devices of open-end spinning machines wherein the opening rollers rotate at speeds of a few thousand rotations per minute. The projection or “cam” elements fastened on their circumference strike the fibers to be individualized at a high speed and accelerate them, while sharply abrasive forces act on the corresponding structural parts of the devices. One possibility of designing the cam elements consists in providing an opening roller with a plurality of needle elements that separate fibers, e.g., from a sliver at every rotation and entrain them. Another technical solution provides designing the cams in the form of a working surface with sawteeth. In this instance, clothing wires in particular have proven themselves that consist of a long metal wire from which the saw-toothed contour is stamped out. The wire produced in this manner is then fastened to the opening roller with a helical groove. Another solution provides designing the opening rollers in one piece. In this instance saw-toothed geometries are formed into a single-piece workpiece, e.g., by turning and grinding. 
   The surface of the cams must therefore be as resistant as possible on account of the high mechanical wear. Moreover, there is the requirement of manufacturing such wear parts as economically as possible and therewith keeping the assembly cost as low as possible. Thus, e.g., especially hard surface coatings or top structures are known; however, they can either not be worked or can only be worked with great difficulty. Furthermore, the surface properties placed on the materials to be worked must be adapted, as result of which the use of certain surfaces that are easier to work is partially excluded. 
   SUMMARY 
   The present invention therefore has the problem of creating an opening device and a method of manufacturing it that permit an improved service life with an especially uniform quality of the products produced along with a simple working and that can also be coordinated particularly well with the products to be worked. Additional objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention. 
   This problem is solved with an opening device characterized in that in particular the clothing wire is pre-bent in accordance with the geometry of a carrier ring and/or the ring has the desired geometry of the finished part. According to the invention, the particular workpiece surfaces have an at least two-layer construction in which an outer layer is a substance layer consisting entirely or partially of especially hard hard-substance components that rests on a substrate layer below it. As the shaping advantageously takes place prior to the application of the outer layer, even especially hard and brittle outer layers can be applied as required onto the wear-stressed surfaces of the opening devices that would otherwise frequently result in exfoliations in a subsequent shaping. Moreover, the qualities of the surface can be varied by varying the hard-substance components inside the outer layer. Thus, a higher amount of hard-substance component results in a surface that is especially resistant but also harder relative to the fibers to be processed and vice versa. In addition to the component, the type of the hard substances worked into the outer layer can be varied as required. This coordination can be adjusted in accordance with the needs of the user, especially the spinning technology requirements. 
   Outer layers have proved to be especially advantageous in this connection whose hardness is greater than 1500 HV [Vickers pyramid hardness], especially greater than 2000 HV. These hardness ranges have proven themselves in practical use and offer especially good service lives with an acceptable handling of the individual fibers at the same time. Even greater hardness values of 2500 HV and more can be achieved in the outer layer, if needed, with the present invention by a suitable selection of the hardness components and their handling. 
   It proved to be advantageous for the application of the outer layer to apply it using a CVD, PVD or plasma CVD method. All methods have the fact in common that they ensure an especially uniform layer thickness. Especially in the PVD and the plasma CVD methods, however, the application of the outer layer can take place at particularly low temperatures. This means that while the method is being carried out, only very slight changes are produced in the grain or texture structures of the substrate materials. 
   It proved to be especially advantageous for the composition of the outer layer if the hard-substance components of the outer layer selectively comprise one or several of the compounds CrN, CN, CrCN, TiN, TiTN, TiAIN, AlTiN, ZrN, NbN, WC or have the qualities of diamond-like carbon steel (DLC). Each of the compounds or materials cited can be used by itself or in combination with one or several of the others. Thus, their qualities can be combined with each other in an advantageous manner as required. 
   The application of the outer layer takes place in an advantageous embodiment of the invention in such a form that the outer layer is designed as a single-component layer. In the single-layer mode of application the outer layer can be applied, as already mentioned, with a freely selectable hard-substance component and/or one or several types of hard substances directly onto the substrate layer. As a result, the quantity and the quality of the outer layer containing hard substances can be especially well adapted to the particular requirements. It is possible in this embodiment already to adapt the wear resistance and the behavior of the material surface to the fibers to be processed by a suitable selection of the type and quantity of the hard-substance components used. 
   In another preferred embodiment of the invention, the outer layer is designed as a multilayer coating. The outer coating is built up in this instance from a plurality of layers. An alternating arrangement of relatively elastic coatings with especially resistant and hard coatings proved to be especially advantageous in this instance. The construction corresponds in this embodiment to a type of sandwich construction. The alternating arrangement of elastic and hard coatings has the advantage that, on the one hand, an especially resistant surface is created and at the same time the flexibility of the structural component is extensively retained by the elastic coatings. This substantially reduces the danger of exfoliations or other separations of the hard surface. 
   Another preferred embodiment of the invention provides that the outer coating contains dispersedly dissolved hard-substance particles with sizes in the nanometer range. So-called nanoparticles are permanently anchored in the outer coating on account of their especially small geometric dimensions and therefore do not separate out of the coating during operation. The particles can distinctly increase the wear resistance of the structural component on account of their hardness and are arranged at the same time in an elastic base body. 
   In order to improve the ability to resist wear, an advantageous embodiment of the invention provides that the outer coating is precipitation-hardened. Precipitation-hardening methods are already known in the state of the art; however, they offer a possibility in conjunction with the present invention of further improving the positive qualities of the devices in accordance with the invention. In particular, the outer coating can be designed to be even more wear-resistant after a precipitation hardening by the selection of suitable dispersedly dissolved hard-substance particles in ηm size. 
   Another advantageous embodiment of the invention provides that the substrate coating, in particular the surface of the wear-stressed sections of the opening device, is tempered prior to the application of the outer coating preferably at the application temperatures of the outer coating. A structural transformation possibly occurring during the application of the outer coating is already anticipated by the tempering. Therefore, the tempering preferably takes place at the same temperature that also prevails during the subsequent application of the outer coating. As already mentioned, the PVD method and the plasma CVD method offer the advantage in this connection of particularly low application temperatures. 
   Coating thicknesses of the outer coating between 2 and 8 μm proved to be especially advantageous. In this range, the applied outer coatings are capable on the one hand of protecting to a sufficient degree the substrate coatings located below them. At the same time, it is assured that the coating thicknesses are not so great that e.g., exfoliations or other separations occur. 
   An entirely different, advantageous embodiment of the invention provides that a carrier layer is applied between the outer coating and the substrate coating. This carrier layer or coating has two functions. The first function is to produce a reliable adhesion between&#39;the substrate coating and the outer coating located above it. The second function of the carrier coating is based on the fact that it compensates rugosities and non-uniform areas in the substrate coating and thus creates an especially uniform bearing area or contact surface for the outer coating. An embodiment provides that the carrier coating is a coating applied by a chemical method. A carrier coating is advantageously used for this purpose that is a chemically applied nickel-phosphorus coating. Chemically applied coatings, especially of the previously cited type, have the advantage that they have extremely uniform coating thicknesses. 
   In order to achieve an especially protective handling of the fibers to be processed, it proved to be especially advantageous if the outer coating is deburred and/or polished. This can basically take place by means of all known deburring means and methods, but chemical and electrochemical deburring have proved to be especially suitable. The especially smooth surfaces of the clothing wires and/or rings worked in this manner handle the fibers to be processed in an extremely protective manner and consequently generate an especially low development of dust during the spinning process. In addition to deburring or instead of it, it is also suitable to polish the outer coating. This can take place, e.g., by a relative motion between the structural component designed in accordance with the invention and a polishing fluid. The polishing fluid conducts hard-substance particles that smooth the surface of the structural component by repeatedly striking it. Examples of hard-substance particles can be, e.g., diamond particles, corundum, silicon carbide or silicon nitride, that all have an especially high degree of hardness. If, for example, an opening device is allowed to rotate for a rather long time in such a polishing fluid, an especially smooth and resistant surface is obtained. 
   Another preferred embodiment of the invention provides that the carrier coating is a coating applied by a galvanic method. It proved to be especially advantageous in this instance if this coating is a galvanically applied nickel coating. Galvanically applied coatings are especially economical to manufacture and can be applied with a sufficient uniformity. 
   An entirely different embodiment of the invention advantageously provides that the carrier coating is an additional hard-substance coating. In contrast to the previously described outer coating with hard-substance components, this hard-substance coating designed as the carrier coating can be optimized, e.g., by a suitable selection of material as regards to a high degree of elasticity and an excellent coupling or adhesion characteristics. 
   The coating thickness of the carrier coating is advantageously between 3 and 10 μm and is therefore slightly thicker than the coating thickness of outer coating. In this instance, as the coating thickness of the carrier coating increases, its ability to compensate rugosities on the substrate coating grows. 
   Certain advantageous embodiments of the invention provide that the carrier coating is tempered at temperatures of 320° C. to 370° C., especially at 350° C. If, e.g., a chemical, applied nickel-phosphorus coating is used as carrier coating, a hardness of 900–100 HV can be achieved by such a tempering in the carrier coating. This is an especially resistant coating on which an outer coating applied to it finds on the one hand especially good adhesion and on the other hand an especially firm base. 
   In the method of the invention for manufacturing opening devices, the particular workpiece surfaces are provided with an at least two-coat construction in which an outer coating is applied onto a substrate coating underneath it, which outer coating is a hard-substance coating and consists entirely or partially of especially hard hard-substance components. The method furthermore suggested by the invention is characterized in that the clothing wire is advantageously pre-bent in accordance with the geometry of a carrier ring and/or that the opening ring is manufactured with the desired geometry of the finished part. Other advantageous embodiments of the invention result from the particular associated subclaims. 
   The invention is explained in detail in conjunction with the following exemplary embodiments and the drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a lateral view of an opening roller in accordance with the invention. 
       FIG. 2  shows a lateral view of the section of a garniture wire. 
       FIG. 3  shows a schematic view of a pre-bent garniture wire. 
       FIG. 4  shows a partial sectional view of an opening roller with garniture wire. 
       FIG. 5  shows a partial sectional view of a one-piece garniture ring. 
       FIG. 6  shows a surface construction in accordance with the invention with a one-layer coating. 
       FIG. 7  shows a surface construction in accordance with the invention with a multi-layer coating. 
       FIG. 8  shows a surface construction in accordance with the invention with dissolved hard-substance particles. 
       FIG. 9  shows a surface construction in accordance with the invention with an additional carrier coating. 
       FIG. 10  shows a surface construction in accordance with the invention and with  FIG. 7  with an additional carrier coating. 
       FIG. 11  shows a surface construction in accordance with the invention and with  FIG. 8  with an additional carrier coating. 
   

   DESCRIPTION 
   Reference is now made to embodiments of the invention, one or more of which are illustrated in the drawings. Each embodiment is provided by way of explanation of the invention, and not meant as a limitation of the invention. For example, features illustrated or described as part of one embodiment may be used with another embodiment to yield still a further embodiment. It is intended that the present invention include these and other modifications and variations. 
     FIG. 1  shows a lateral view of an opening roller  1  in accordance with the invention. Clothing wire  3  is arranged on carrier ring  2  on its radially outer side. This wire is arranged on carrier ring  2  with a plurality of windings and with a constant rise in the axial direction. Opening roller  1  in accordance with the invention rotates in the normal operating state with a high speed about axis of rotation  4 . The fibers supplied in the radial direction to opening roller  1 , e.g. in the form of a sliver, are grasped by the raised projections or “cam” elements of a working surface, such as wire  3 , and are loosened out of the composition. As a consequence of the high speed and of the continuous operation, the cam elements are subjected to especially high mechanical wear. 
     FIG. 2  shows a section of a clothing wire  3  in a lateral view. The wire  3  comprises foot area  5  serving for fastening to carrier ring  2 . The use of foot profiles coordinated with grooves in carrier ring  2  have proven themselves well in practice for fastening the wire  3 . The cam elements, that are designed in the present instance in the form of teeth  26 , are located on the top of the wire  3 . Teeth  26  comprise a rather flatly rising shank  6  on one side and on the opposite side a rather sharply falling shank  7 . As a rule, a point  8  formed between the two shanks is inclined toward one side that imparts direction of rotation  9  to opening roller  1 . 
     FIG. 3  schematically shows the helical winding of clothing wire  3 , that is pre-bent with given diameter d. Diameter d corresponds either exactly or at least nearly to the outer diameter of carrier ring  2  or to the diameter of the groove bottom of the associated groove on carrier ring  2 . As a consequence, pre-fabricated wire  3  no longer has to be subjected to any substantial deformations in order to be mounted on carrier ring  2 . Therefore, coatings arranged on the surface of the wire  3  are hardly exposed to deformations any more during the mounting process. 
     FIG. 4  shows one half of an opening roller  1  in accordance with the invention in an axial sectional view. The body of carrier ring  2  is characterized with a coarse hatching on the sheared edge. Spiral groove  10 , in which clothing wire  3  characterized with a fine shading is inserted, is worked into carrier ring  2 . 
     FIG. 5  shows another possible embodiment of opening roller  1 . In this instance, the opening roller has a working surface in the form of a clothing ring  11 . In this embodiment, ring  11  with points  8  arranged on it is designed in one piece. The manufacture of such a ring  11  can take place, e.g., by machining work on a lathe followed by a subsequent working in of the tooth contours by grinding work in the direction transverse to the tooth webs previously manufactured by machining. 
     FIG. 6  shows a design in accordance with the invention of a first preferred embodiment of the invention. In this instance, the upper side is the outside of the workpiece and the lower side shows the area in the direction of the workpiece interior. The material of clothing wire  3  or of clothing ring  11 , designated in the following as substrate  12 , constitutes the lower substrate coating. Outer coating  13  is applied onto substrate  12 , which outer coating preferably has a coating thickness of 2–8 μm. The application of an outer coating  13  takes place by means of a PVD, CVD or plasma CVD method. However, PVD and plasma CVD methods are preferably used since they can be carried out at distinctly lower coating temperatures than the CVD method. This avoids thermally caused structural changes in substrate  12  during the application of the coating. In order to improve the ability to retain the dimensions and shape of the workpiece to be manufactured, substrate  12  is subjected prior to the application of outer coating  13  to a tempering process. The temperature of the tempering preferably corresponds to the temperature at which outer coating  13  is applied. In this manner, the structural changes that otherwise occur during the application of outer coating  13  are anticipated. Outer coating  13  is formed as a single-layer coating in this embodiment. Hard-substance components are contained in this outer coating  13  that can be adapted both in their quality as well as in their quantity to the particular requirements. Examples of materials that can form hard-substance components are the already-described material and elements such as chromium, titanium, aluminum, zirconium, niobium, tungsten carbide compounds, etc., as well as materials with diamond-like properties and known under the designation DLC. 
     FIG. 7  shows the schematic construction of the surface structure of another advantageous embodiment of the invention. Substrate  12  is again shown in the lower area, which has the same qualities as substrate  12  already described previously in  FIG. 6 . However, outer coating  13  located above it is constructed differently in this embodiment in as far as it is a multi-layer coating. The outer coating again has a coating thickness of preferably 2–8 μm. However, now two different materials are combined with one another in an alternating, superposed manner. This sandwich-like arrangement of coatings allows different types of materials and their advantageous qualities to be able to be combined with each other which at the same time makes it possible to use particularly elastic and particularly resistant materials in outer layer  13 . Thus, for example, first coating  14  shown without shading can be a particularly elastic coating that unites a particularly resistant second coating  15  above it permanently to substrate  12  and the coatings under it. If a structural component built up in this manner is subjected to deformations the intrinsic tensions produced in hard coatings  15  are distinctly less than would be the case in a hard-substance layer extending homogeneously over the entire coating thickness. Consequently, exfoliations either do not occur at all or at least occur only under extreme conditions. 
     FIG. 8  shows another advantageous embodiment in which substrate  12  was again retained unchanged. Outer coating  13 , however, contains dispersedly dissolved hard-substance particles  13   a  in nanometer size, applied on it. It is to be noted that the conditions of magnitude shown in  FIG. 8 , in particular those of hard-substance particles  13   a , do not reflect the real magnitude scale. The incorporation of dissolved hard-substance particles  13   a  significantly increases the wear resistance of outer coating  13 . In addition, there is the possibility of improving the outer coating in its ability to resist by an appropriate selection of the material of hard-substance particles  13   a  and a post-treatment as nanodisperse, precipitation-hardened coating. Even in this embodiment, the coating thickness of outer coating  13  was made in the range of 2–8 μm, so that the coating on the one hand offers sufficient wear reserves and at the same time no exfoliations occur on account of excessive intrinsic tensions. 
     FIG. 9  shows another advantageous embodiment of the invention in which an additional carrier coating  16  is arranged between outer coating  13  known from  FIG. 6  and substrate  12  also known from this figure, which carrier coating  16  preferably has a coating thickness of 3–10 μm. Carrier coating  16  has two tasks. The first task is to improve the adhesion between outer coating  13  and substrate  12 . The second task is to compensate rugosities present on the surface of substrate  12  and make an especially well-prepared bearing area available for outer coating  13 . Carrier coating  16  is selectively applied with a chemical method or a galvanic method. A chemical nickel-phosphorus coating is especially suitable for the chemical method and a galvanic nickel coating for the galvanic method. The surface produced in this manner is especially clean and free of disturbances and, in addition, can be especially well reproduced in industrial use. Furthermore, an especially high degree of hardness can be achieved here already given appropriate carrier coatings. If a nickel-phosphorus coating is used as carrier coating its surface can achieve hardness values of approximately 1000 HV by tempering at preferably 350° C. This produces an especially advantageous foundation for outer coating  13  to be subsequently applied on it that is especially hard as well as level and in addition offers a good coupling. 
     FIGS. 10 and 11  show substrate  12  and outer coating  13  again as they have already been described in  FIGS. 7 ,  8 . However, in distinction to the previous figures, carrier coatings  16  of the invention are arranged between outer coating  13  and substrate  12 . 
   The present invention is not limited to the exemplary embodiment shown, but rather numerous variations of the invention are possible within the scope of the claims. Thus, e.g., instead of the hard-substance components cited in the subclaims other suitable materials and compounds with other properties can be used. Also, the coating constructions described for the opening device can be used on other wear-stressed structural components of textile machines such as, e.g., yarn draw-off nozzles or rotors. Furthermore, it is conceivable to mix the hard-substance components with other materials, to alloy them or to use them in a pure form.