Patent Application
20080276594
The present invention relates to an air jet aggregate for an air jet spinning apparatus for producing a spun thread from a staple fiber strand, including a vortex chamber and a number of fluid-feeding injector channels running into the vortex chamber. At least two injector channels are provided, which have differing angles of inclination in relation to a parallel to the axis of the spun thread.
In an air jet spinning apparatus, the fibers of a twist-free fed staple fiber strand are imparted a spinning twist by way of an air jet, which lends the formed thread its tensile strength. The staple fiber strand is fed into a vortex chamber, in which a rotating vortex current prevails, which is usually generated by injector channels which run into the vortex chamber and to which injector channels pressurized air is applied.
It is known, for example, in German published patent application DE 41 22 216 A1, to arrange a number of injector channels in the circumferential wall of the vortex chamber. In the known air jet aggregates, all injector channels for pressurized air always have the same angle of inclination in relation to a parallel to the axis of the spun thread. The injector channels are usually supplied with pressurized air from a joint pneumatic source via a ring channel.
It is further known that the pressurized air injected into the vortex chamber must fulfill two functions. First of all, the pressurized air must form a rotating vortex current, which gives the fibers of the fed staple fiber strand their twist. Secondly, the pressurized air must flow into the vortex chamber in such a way that a sufficiently strong vacuum occurs at the entry opening of the fiber feed channel, through which the staple fiber strand is transported from the delivery nipping line into the vortex chamber.
A disadvantage in the known air jet aggregates is that the angle of inclination of the injector channels must be predefined as a compromise between two contradictory requirements. The smaller the angle of inclination is, that is, the more it approaches the parallel to the axis of the spun thread, the greater the vacuum at the entry opening of the fiber feed channel and the better the fiber take-over from the delivery roller pair. At the same time however, the tangential forces of the vortex current which twist the staple fiber strand around its axis decrease, and the spun thread only has a low level of tensile strength. If a large angle of inclination is selected for the injector channels, that is, almost 90° to the axis of the spun thread, the rotating vortex current does generate a thread of high tensile strength, but there is, however, less vacuum at the entry opening, which impairs the suction action of the air jet aggregate and the fiber transport into the vortex chamber, which in turn can lead to end breaks.
An air jet aggregate is also known in German patent application DE 41 22 216 A1, in which a further injector channel for a fluid is described, which is arranged coaxially to the axis of the spun thread. This injector channel serves exclusively to feed water into the vortex chamber, whereby the spun fiber material is dampened. The aim is to improve the tensile strength of the spun thread by means of direct dampening during spinning and to omit large humidifiers for the atmosphere.
It is an object of the present invention to avoid the above mentioned disadvantages and to create an air jet aggregate which possesses a good twist distribution and a good suction action.
This object has been achieved in accordance with the present invention in that at least two injector channels having differing angles of inclination are connectable to at least one pressurized air source.
By use of at least two injector channels having different angles of inclination, to all of which pressurized air is applied, the vortex current in the vortex chamber can be influenced in an advantageous way. At least one, but advantageously a number of injector channels are arranged in position and angle of inclination in such a way that a good distribution of twist for the fibers of the staple fiber strand is guaranteed and a thread having high tensile strength is formed. A relatively large angle of inclination and an opening of the injector channels running tangentially into the vortex chamber are particularly advantageous. To secure a good suction action and to guarantee a reliable transport of the staple fiber strand from the delivery roller pair into the vortex chamber, at least one further injector channel supplied with pressurized air is provided, which injector channel has a smaller angle of inclination than the above mentioned injector channels for twist distribution. The injector channel with the smaller angle of inclination effects essentially the occurrence of a vacuum at the entry opening of the fiber feed channel.
It can be advantageous that the minimum one injector channel for generating a vacuum is at a different distance, in particular a shorter distance, from the entry opening than the injector channels for twist distribution. The proximity to the entry opening intensifies the vacuum formation.
It is advantageous for a particularly good suction action of the air jet that at least one injector channel for pressurized air has an angle of inclination of less than 5°, preferably even 0°, that is, this injector channel extends essentially parallel to the axis of the spun thread.
In an embodiment of the present invention, it can be advantageous to arrange the injector channel in such a way that its opening is directed towards the center of the rotating vortex current. Disturbances in the rotation of the vortex current can thus be avoided to a large extent.
It can be provided that all injector channels are connected to a joint pressurized air source. In this case, the vortex current can be adjusted accordingly, for example, based on the number and diameter of the injector channels selected.
In an embodiment of the present invention, it is, however, advantageous that at least two injector channels having different angles of inclination are connectable to separately adjustable pressurized air sources. The pressure and/or the amount of air flowing through the different injector channels can be altered during the spinning process due to the separately adjustable pressurized air sources. This permits, in an advantageous way, the generation of a helical curve-shaped vortex current with alterable pitch in the vortex chamber from the pressurized air flowing out of the injector channels. It is advantageous that the vortex current follows a helical curve with a pitch, which is adapted to the delivery speed of the spun thread and its twist.
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.
The air jet spinning apparatus according to
The delivery device 1 includes a delivery roller pair 5, 6, which is arranged to the air jet aggregate 3 at a short distance thereto and whereby the front roller pair of a drafting device (not shown) can be involved. A drafting device of this type drafts a fed sliver or roving to a staple fiber strand 2 of the desired degree of fineness in a known manner. The delivery device 1 can, however, alternatively be a nipping roller pair of another drafting device or any other unit arranged upstream thereof. A nipping line is denoted by the reference 7, at which the staple fiber strand 2, fed in feed direction A, is nipped before running in to 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, among other things, a fiber feed channel 8 and an essentially hollow cylindrical vortex chamber 9. A fluid device generates, in the vortex chamber 9, a vortex current by blowing in pressurized air through the injector channels 10, which run into the vortex chamber 9. The injector channels 10 extend from an annular space 11, which is supplied with pressurized air via a pressurized air source 12 (shown only as a conduit here). The current flow direction of the pressurized air is denoted by the arrow C. The injector channels 10 have an angle of inclination a in relation to a parallel 13 to the axis of the spun thread 4, which lies advantageously between 30° and 90°.
In addition, the injector channels 10—as can be seen in FIG. 2—run tangentially into the vortex chamber 9, whereby a rotating vortex current occurs. It should be mentioned at this point that the injector channels 10, which lie skewed in space, are here shown projected into the drawing plane for reasons of clarity in
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 fed from the fiber feed channel 8 essentially without receiving twist to the thread withdrawal channel 16. On the other hand, the fibers in the area between the fiber feed channel 18 and the thread withdrawal channel 16 are subjected to the effect of the vortex current, which drives the fibers (or at least their end areas) radially away from the entry opening 19 of the thread withdrawal channel 16. The threads 4 produced in this way have, therefore, a core of fibers essentially extending in thread longitudinal direction (or fiber areas without any significant twist) and an outer area in which the fiber or fiber areas are twisted around the core.
The rotation of the vortex current in the vortex chamber 9 is influenced by the angle of inclination α of the injector channels 10. The larger the angle of inclination α is made, the stronger the rotation of the vortex current and the greater is the tensile strength of the spun thread 4.
For the fault-free operation of the air jet aggregate 3, it is, however, necessary that a sufficiently strong vacuum be present at the entry opening 20 of the fiber feed channel 8. The vacuum at the entry opening 20 ensures the transport of the staple fiber strand 2 from the nipping line 7 of the delivery roller pair 5, 6 into the vortex chamber 9. The intensity of the vacuum at the entry opening 20 can also be influenced by the angle of inclination α of the injector channels 10, namely the smaller the angle of inclination α, the greater the vacuum. In the known air jet aggregate 3 of prior art, the injector channels, to which pressurized air was applied, were always arranged at the same angle of inclination α. This angle of inclination α was disadvantageously predefined as a compromise between the above mentioned contradictory requirements.
In the case of the air jet aggregate 3 according to the present invention, two further injector channels 21 for pressurized air are provided. The injector channels 21 extend out from an annular space 22 and run into the vortex chamber 9 at a smaller angle of inclination than the injector channels 10. The injector channels 21 shown in
By way of the presence of injector channels 10 and 21 having different angles of inclination α, the vortex current in the vortex chamber 9 can be optimally adapted to the desired features, as the rotation of the vortex chamber and the vacuum occurring at the entry opening 20 can now be separately influenced. As a result, a helical curve-shaped vortex current with alterable pitch can be generated in the vortex chamber with the pressurized air flowing out of the injector channels 10 and 21.
The separate influencing of the vortex current by use of the different injector channels 10 and 21 can be achieved even more effectively the shorter the distance is between the entry point of the injector channels 21 in the vortex chamber 9 and the entry opening 20, that is, the further upstream—as seen in transport direction—the injector channels 21 are arranged. By providing a smaller distance between the injector channels 21 and the entry opening 20, a stronger vacuum can be achieved at the entry opening 20 at a lower airflow rate.
It is particularly advantageous to design the pressurized air source 12 and the pressurized air source 23 in such a way that the parameters of the in-flowing pressurized air, for example air pressure or air volume, can be regulated separately during the spinning process. It is then possible in an advantageous way to adapt the vortex current in the vortex chamber 9 to the changing parameters of the staple fiber strand 2 to be spun. For example, it can be advantageous when, during the spinning process, the delivery speed in direction A and the thread withdrawal speed in direction B are increased, to simultaneously increase the air pressure of the pressurized air flowing throw the injector channels 21, in order, for example, to adapt the air speed in the fiber feed channel to the increased speed of the staple fiber strands 2. The shown air jet aggregate 3 demonstrates the great advantage of a very variable application.
Finally reference is made to the fact that the shown number of injector channels 10 and 21 is only an example and can be varied according to requirements.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2005045-703.7 | Sep 2005 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP06/07095 | 7/19/2006 | WO | 00 | 3/18/2008 |
