Patent Application
20080115476
The present invention relates to an air jet spinning arrangement for producing a spun thread from a staple fiber strand, including an essentially hollow cylindrical vortex chamber, whose peripheral wall has a supporting surface for a peripheral surface of a rotationally symmetrical insert in the running-in area of the staple fiber strand. A number of air jet slits are worked into the peripheral surface of the insert, which air jet slits are completed to form closed compressed air channels by of way of the supporting surface. The nozzle-like mouths of the compressed air channels are arranged on the front side of the insert facing the vortex chamber.
In air jet spinning arrangements, the compressed air channels should conduct the jets of air in an oriented way into the vortex chamber such that an air vortex is formed therein, which contributes significantly to imparting the spinning twist of the spun thread. The most optimal energy-efficient situation is achieved when the compressed air channels enter the vortex chamber with a completely tangential component.
Compressed air channels have usually been drilled up to now. As these bore holes have very small diameters in the range between 0.5 mm and 0.6 mm, and must be at least 3 mm long for fluidic reasons, a ratio arises between the length of the bore holes and their diameter, which ratio is greater than 5. With regard to production, these are proper deep bore holes, which are relatively hard to produce. This difficulty is increased when the bore holes are, in relation to the thread path, not only tangential but extend with a further component axially thereto.
From German published patent application DE 37 32 708 A1, compressed air channels for air jet spinning arrangements are known, which compressed air channels are worked into the peripheral wall of a component in the form of slits, which are only then completed to form the compressed air channels when assembled, by covering the slits with another component. For example, in the known arrangement, linear slits are worked into the conical surface and covered subsequently by a correspondingly formed conical surface. By offsetting the slits in relation to the thread, it can be additionally achieved that a more or less greater air vortex can be exerted on the thread.
The compressed air channels of the laterally mentioned type have the advantage in that they can be very easily produced. Because the compressed air channels are uncovered in the form of air jet slits before assembly, their exactness can be checked in a simple way and, if necessary, they can be re-worked. During this examination, defective parts can also be sorted out.
It is an object of the present invention, while retaining the advantages in German published patent application DE 37 32 708 A1 for an air jet spinning arrangement, to create nozzle channels which are further optimized, and by means of whose nozzle-like mouths, the compressed air which imparts the spinning twist enters the vortex chamber having the greatest possible tangential component.
This object has been achieved in accordance with the present invention in that the air jet slits are designed in the form of a multiple-start thread.
Because air jet slits formed in this way have, when they run into the front side of the insert, a component in a running direction of the forming thread, and also, due to their thread-like design, a pronounced component in a circumferential direction of the vortex chamber, nozzle channels arise which are near optimal. The insert containing the multiple-start thread is appropriately pressed into the borehole having the supporting surface, which gives rise simultaneously to good sealing properties.
It should be specified here that within the framework of the present invention, protective rights are sought also for a kinematic reversal, in which the air jet slits in the design of a multiple-start thread are placed not in the insert, but rather in the supporting surface surrounding the insert.
The embodiment is then particularly simple when the thread is worked into a peripheral surface designed as a cylinder. For the purposes of the invention, more or less conical or convexly rounded peripheral surfaces are possible, but the cylindrical form is particularly simple to produce. In addition, a cylindrical form enables the insert to be axially moved within limits, so that the height of the vortex chamber is altered, which in turn influences the character of the spun thread.
The depth of the multiple-start thread forming the air jet slits can by all means vary over the length of the air jet slits. Thus, nozzle channels can be produced, in which the depth of the thread tapers from entry to exit. In reverse, the air jet slits can widen towards the exit, when for example the effect of a laval nozzle is required.
All the considered forms of the air jet slits are completed to form the finished nozzle channels by way of covering with the supporting surface when assembly takes place.
These and further objects, features and advantages of the present invention will become more readily apparent from the following detailed description thereof when taken in conjunction with the accompanying drawings, wherein:
The air jet spinning arrangement according to
The delivery device 1 includes a delivery roller pair 5, 6, which is arranged upstream of the air jet aggregate 3 at a short distance, and which can be formed by the front rollers of a drafting device (not otherwise shown). A drafting device of this kind drafts in the known way a fed sliver or also a roving to a staple fiber strand 2 to the known degree of fineness. The delivery device 1 can, alternatively, be a nipping roller pair of another drafting arrangement or of any other aggregate arranged upstream thereof. A nipping line is denoted by the reference number 7, at which the staple fiber strand 2, fed in delivery direction A, is held nipped before running into the air jet aggregate 3. The air jet aggregate 3 generates the twist for the thread 4 to be spun and delivers the thread 4 in thread withdrawal direction B by way of a withdrawal roller pair (not shown).
The air jet aggregate 3 includes a fiber feed channel 8 and an essentially hollow cylindrical vortex chamber 9. A fluid device generates an air vortex in the vortex chamber 9 by injecting compressed air through compressed air channels 10 which run into the vortex chamber 9. These compressed air channels 10, the embodiments of which are described in more detail below with the aid of
In the end area of the fiber feed channel 8, an edge 17 of a fiber guiding surface 18 is arranged as a twist stop, which edge 17 lies eccentrically to the thread withdrawal channel 16 in the area of its entry opening 19.
In the air jet aggregate 3, the fibers to be spun are held on the one hand in the staple fiber strand 2 and thus guided from the fiber feed channel 8 essentially without a spinning twist into the thread withdrawal channel 16. On the other hand, the fibers are subject to the action of a vortex current in the area between the fiber feed channel 8 and the thread withdrawal channel 16, by which the fibers (or at least their end areas) are driven radially away from the entry opening 19 of the thread withdrawal channel 16. The threads 4 produced in this way therefore display a core of fibers extending essentially in thread longitudinal direction or fiber area without any significant twist and an outer area in which the fibers or fiber areas are bound around the core.
It is evident that the vortex current has an ideal effect then when the jets of compressed air enter the vortex chamber 9 as tangentially as possible. At the same time, however, a significant component in the direction of the thread withdrawal channel 16 is ideally present, so that an injection effect can act on the fiber feed channel 8, which injection effect is necessary for sucking in the staple fiber strand 2. The performance required at the compressed air channels 10 should be accomplishable despite the small dimensions.
In order to achieve this, a rotationally symmetric insert 20 for the production of the compressed air channels is provided, which is inserted with its peripheral surface 21 in a correspondingly adapted peripheral wall 22 of the vortex chamber 9. The peripheral wall 22 is situated in the running-in area 23 of the vortex chamber 9. The nozzle channels 10 in the form of air jet slits 24 are worked into the insert 20, which air jet slits 24 are completed after assembly to form closed compressed air channels 10 by way of the peripheral wall 22. This process is described below with the aid of
As can be seen, the air jet slits 24 begin at the above-mentioned annular space 11 and open out at the front side 25 of the insert 20. The lead of the thread is chosen in such a way that a significant component of the compressed air stream is present in the direction of the path of the thread 4. It can be seen that, due to the embodiment of the air jet slits 24 in the form of a multiple-start thread, a well-defined compressed air component inevitably also occurs, which rotates along the peripheral wall 22 of the vortex chamber 9.
The depth of the thread can remain constant along the length of the air jet slits 24, but can, if required, become deeper or shallower.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2004 052 206.5 | Oct 2004 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP05/11192 | 10/18/2005 | WO | 00 | 11/6/2007 |
