Patent Application
20070277497
This application claims the benefit of German patent application 102004005429.0, filed Feb. 4, 2004, herein incorporated by reference.
The invention relates to a fiber guide channel for an open end spinning device, for the pneumatic transportation of individual fibers, which are combed out of a feed fiber band (e.g., a sliver) by an opening cylinder rotating in an opening cylinder housing, to a spinning rotor running at a high speed in a rotor housing that can be subjected to a negative pressure and a method for producing such a fiber guide channel.
Fiber guide channels have been known for a long time in conjunction with open end spinning devices, in particular with open end rotor spinning devices and are described in numerous patent applications.
High demands are made of the design of fiber guide channels of this type, in which a pneumatic transportation of individual fibers takes place, in particular with regard to the geometric configuration and the surface quality. In other words, the flow conditions inside a fiber guide channel of this type must ensure that the fibers as far as possible remain drawn or are drawn during transportation. In addition, the surface of these components has to be continuously smooth, so that during pneumatic transportation of the fibers, no fibers can become fixed. Damaging air eddies being able to form in the boundary layer region of the fiber guide channel should be avoided, in particular, here.
With regard to the production of fiber guide channels of this type, various manufacturing methods have also been known for a long time.
Fiber guide channels, which are completely or partially manufactured from steel sheet parts, are described, for example, in German Patent Publications DE-AS 23 64 261, DE-OS 28 00 795 or DE 195 11 084 A1.
According to German Patent Publication DE 28 00 795 A1 it is provided, for example, that a fiber guide channel mechanism is produced initially in a first working step from a steel sheet. This pre-manufactured component then has liquid aluminum, for example, cast round it in a pressure casting mold. This production method has not, however, found a way into practice as the problems occurring could not be satisfactorily solved. It had been found, for example, that the fiber guide channel mechanism pre-manufactured from steel sheet deforms in the pressure casting mold owing to the high pressure and therefore has to be laboriously supported. Moreover, in this production method, there is constantly the risk of excess casting material penetrating into the fiber channel and this has a negative effect on the surface quality thereof.
The fiber guide channel mechanism according to German Patent Publication DE 195 11 084 A1 is also configured as a cold-formed steel sheet part. In this mechanism, however, the steel sheet part can be fixed, so as to be replaceable, in a corresponding receiving hole of a pre-manufactured opening cylinder housing and sealed relative to the opening cylinder housing by an O-ring seal resting on the outer periphery of the fiber guide channel mechanism.
Compared to the channel plate, this known fiber guide channel mechanism is sealed by means of a special hose nozzle. However, it has been found in practice that sealing problems can occur, which do not allow proper spinning operation, in steel sheet constructions of this type.
Furthermore, fiber guide channels, which are configured as pressure cast parts, are described in German Patent Publication DE 197 12 881 A1. These known fiber guide channels have a foot part with a centering mechanism and an annular groove for receiving a sealing ring and can be fixed at a precise angle and in an air-tight manner via this foot part in a corresponding hole of the opening cylinder housing. The fiber guide channel opens in the region of a central channel plate adapter receiver in a hole, this region also being sealed in an air-tight manner via a corresponding seal. The fiber guide channels according to German Patent Publication DE 197 12 881 A1 are also provided with wear protection, for example by immersion in a nickel dispersion bath.
The above-described fiber guide channels have succeeded, in principle, in practice and are used in large numbers in open end rotor spinning devices. However, the production of fiber guide channels of this type as a zinc or aluminum pressure casting is very expensive and leads to permanently high mold costs. Moreover, in this manufacturing method, the reject quota is relatively high, in particular owing to the high quality demands on the surface quality of the fiber guide channels.
Proceeding from the aforementioned prior art, the invention is based on the object of developing a fiber guide channel and a method for producing fiber guide channels, which allows economical manufacture, i.e. manufacture which is as low as possible in rejects, of fiber guide channels, in which limits which are too narrow should not be set either with regard to the shaping of the fiber guide channels.
This object is achieved according to the invention by a fiber guide channel for an open end spinning device, characterized in that the fiber guide channel is configured as a hollow body, the internal cross-section of which decreases toward its orifice, the fiber guide channel being produced at least partially by a manufacturing method, in which a first over-sized blank shape is initially produced by injection molding from a mixture of a sinterable material and a binder and is converted into a porous intermediate shape by removing the binder and brought into a final shape which requires little finishing by sintering.
A preferred method for producing a fiber guide channel of this type is characterized in that the fiber guide channel is produced at least partially by the following method steps: producing a mixture from a sinterable material and a binder, producing a blank body from this mixture by powder injection molding, releasing the blank body from its binder portions and hardening the porous blank body by sintering into its final shape.
Advantageous further configurations, features and characteristics of preferred embodiments of the fiber guide channel and the method of its formation according to the present invention are described more fully hereinbelow.
The fiber guide channels according to the invention, in particular, have the advantage that they are substantially free of procedural restrictions with regard to the outer and inner form. In other words, the fiber guide channels are hardly subjected to any restrictions with regard to their shaping even in the region of their internal cross-section and can easily be provided with a channel profile which is optimized in terms of flow. As the reject quota is extremely low in the production method provided, economical manufacturing of fiber guide channels of this type is also possible.
The final bodies produced after sintering can be subjected, in this case, virtually without further finishing in subsequent finishing processes, to virtually any conceivable heat treatment and surface treatment methods. In other words, because in fiber guide channels, which are produced by the above-described manufacturing method, a large part of the otherwise conventional, relatively expensive finishing work is dispensed with and the reject quota is very low, the fiber guide channels according to the invention can be manufactured without many process steps and therefore economically and with a high quality.
A corresponding method is also called MIM or PIM technology (Metal Injection Molding—MIM or Powder Injection Molding=PIM). To produce fiber guide channels by MIM or PIM technology, initially an organic binder is mixed with a sinterable material, for example a very fine (<20 μm), generally spherical metal powder or an oxide ceramic powder to form a homogeneous mass or processed to form so-called pellets. The volume portion of the metal powder or of the oxide ceramic powder in this homogeneous mass is generally over 50% in this case. The mass obtained is then handled similarly to plastic material processing on injection molding machines. In other words, blank bodies are manufactured from this mass by means of an injection molding machine and already have all the typical geometric features of the fiber guide channel to be produced, but still possess a volume which is enlarged by the binder content. The organic binders are then removed from the blank bodies in a so-called binder removal process. The remaining porous intermediate bodies are then compacted by sintering in various protective gasses or a vacuum to form fiber guide channels with the final dimensions. The shrinkage occurring in this case can lead to final sizes greater than 96%.
Basically, in the use of MIM or PIM technology there is also the possibility of influencing the inner contour or the internal width of the fiber guide channels by targeted mass concentration, for example. In other words, the shrinkage behavior of the blank body can be controlled by reinforced, outer mass application in certain regions of the fiber guide channel and therefore, for example, the demolding slopes produced during production of the blank body, can be counteracted.
Owing to the material of the sinterable material, for example metal power or oxide ceramic powder, the grain size of the sinterable material and the selection of the binder removal and/or sintering parameters, the surface structure of the fiber guide channel can be influenced in a targeted manner. In other words, the most favorable surface structure for further processing or heat treatment can already be fixed in advance.
In the use of the above-described method, there is obviously the possibility of configuring the fiber guide channels either in one part or else so as to be multi-part.
In a multi-part configuration, it is advantageous if at least one insertion piece which is arranged in the region of the inlet opening of the fiber guide channel and forms the fiber tear-off edge and therefore is subjected to high loading, is produced by MIM or PIM technology, as an insertion piece produced in this manner is already very wear-resistant and can then be still further improved without problems by corresponding finishing. In other words, in fiber guide channels produced by MIM or PIM technology, the so-called eggshell effect (=hard shell but soft core) is avoided. The components produced have a continuously high wear-resistance. The surfaces which come into contact with the fibers can be additionally improved in this case in a relatively simple manner, for example by chrome plating.
In the case of one-part fiber guide channels, the surface quality of the fiber guide channel, in particular, can be optimized in a relatively simple manner by chrome plating or the like. In other words, a very smooth surface of the fiber guide channel can be produced by a corresponding coating and this has a very positive effect on the flow conditions inside the fiber guide channel and therefore, as a whole, on the spinning result of the entire mechanism.
The fiber guide channels manufactured according to the invention or the insertion pieces may advantageously also be subjected to another heat treatment known per se, for example nitration, boration, etc. Heat-treated components of this type are distinguished by a long service life.
The invention will be described in more detail hereinafter with the aid of an embodiment shown in the drawings, in which:
The open end rotor spinning device 1 shown in
Fixed to the cover element 8, which is mounted so as to be rotatable to the limited extent about a pivot pin 16, is an opening cylinder housing 17. The cover element 8 also has rear bearing brackets 19, 20 for mounting an opening cylinder 21 or a fiber band take-in cylinder 22. The opening cylinder 21 is driven in the region of its wharve 23 by a peripheral tangential belt 24 along the length of the machine, while the drive of the fiber band take-cylinder 22 is preferably implemented via worm gear arrangement (not shown), which is connected on a drive shaft 25 along the length of the machine.
The fiber guide channel 13 is sealed with respect to the channel plate 37, for example, via a hose nozzle 38, which is supported on a contact shoulder 41 on the fiber guide channel 13.
The fiber guide channel 13 produced by MIM or PIM technology and shown in a front view in
As can be seen from
An increase of this type in the flow speed of the transporting air flow in the region of the inlet opening can also be achieved by the use of a multi-part fiber guide channel 13 shown in
In a further embodiment (not shown), the insertion piece 27 may obviously also be configured such that the internal cross-section of the fiber guide channel 13 is not constricted. At least the insertion piece 27 is also manufactured by MIM or PIM technology in a multi-part fiber guide channel 13 of this type.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2004 005 429.0 | Feb 2004 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP04/14786 | 12/29/2004 | WO | 5/4/2007 |
