Patent Application
20060010656
The present invention relates, according to the preamble to the independent Patent Claims 1, 11, and 12, to a housing with a pair of rollers mounted inside it, a drafting device with a housing of this type, as well as a textile machine with a corresponding drafting device.
Drafting devices are used in textile technology for the drafting or drawing of fibre slivers in spinning machines. Following the drawing process, the fibre slivers which are drawn in the drafting devices are spun by means of a spinning process to form a yarn. The invention described hereinafter is concerned with the adjustment, or adjustability, of the drafting devices referred to, i.e. the adjustability of the drafting distances in a drafting device. A drafting device consists of at least two pairs of rollers, but for preference of three or four pairs of rollers. A fibre sliver running through the drafting device is drawn by the different rotation speeds of the pairs of rollers. The drawing or drafting takes place between two pairs of rollers following in succession, i.e. in the area between the nip lines of the two pairs of rollers. The distance between two such nip lines is also referred to as the nip or grip distance. Located within such a nip distance is a drafting zone, in which the fibres of the fibre sliver are drawn against one another. Three-roller drafting devices with a preliminary drafting zone and a main drafting zone are widespread. In order to achieve optimum guidance and optimum drawing of the fibres in the drafting devices, the nip distances of the individual drafting zones must be adjusted to the staple length of the fibres which are to be processed. In the drafting zones, the optimum nip or grip distance is slightly longer than the longest fibres which are to be processed (by about 2 mm). In order to adjust the nip distances to the staple fibres to the optimum amount, the drafting zones must accordingly be adjustable steplessly or at least in very small steps (step length approx. 1 mm); this applies in particular to the preliminary drafting zone. The adjustability of the nip distance in the preliminary drafting zone is of particular importance because it is here that genuine drawing or drafting processes of 1.1 to 5 times are carried out, without an additional external fibre guide (such as an apron) being present. For the main drafting zone (with drafting or drawing procedures of about 10 to 100 times), adjustability of the nip distance is likewise of advantage, even if in this case the fibre guidance is guaranteed by the aprons which are usually present. It is sufficient in this case, however, if the nip distance is adjustable in from two to a maximum of five steps.
It is generally usual (e.g. with ring-spinning drafting devices), when adjusting the nip distance, always to move two axles of a roller pair (see in this connection, for example, DE 1 123 959 or DE 1 122 885). That is to say, both the driven roller as well as the loaded top roller are moved together. These devices demonstrate the disadvantage of conventional drafting devices. The adjustment of the pairs of rollers when the fibre material which is to be processed is changed is associated with a considerable amount of work. This applies in particular if the main drafting or drawing distance must he changed, since in this case both the lower as well as the upper aprons and all upper apron cages must be replaced.
One possible arrangement for this problem is disclosed by DE 489 810, although only for single-apron drafting devices which were used in earlier times. The adjustable upper intake roller disclosed in DE 489 810 is mounted on a guided carriage and is pressed by means of screws against the lower roller which pertains to it. Thanks to the simple design of single-apron drafting devices and the absence of an upper apron, the adjustment of the upper roller was easy to carry out.
With modern double-apron drafting devices, adjustability of this kind is no longer possible, since the upper roller carries an apron.
With the device according to DE 1 122 885, both rollers of the pair of inlet rollers are moved. This can be derived from their Description, since the device is intended to be suitable for the processing of short-staple and long-staple fibres, i.e. from cotton to wool. Because it must be possible for widely differing nip distances to be adjusted in order for such suitability to be attained, the text cannot disclose anything other than the joint adjustment of upper and lower rollers. The use of such a single-apron drafting device for the processing of short-staple as well as long-staple fibres is no longer conceivable in modern machines. Long aprons would be necessary for this, which, with the present-day speeds of high-speed drafting devices (speeds greater than 100 m/min), would begin to flutter.
A further device for the adjustment of pairs of rollers is disclosed by EP 362 477 A1. The device which is disclosed in this, however, relates to what are referred to as drafting or drawing frames. Drafting or drawing frames do not contain any aprons, since they are only required to achieve far fewer draftings. In return, however, they exhibit very high delivery speeds of up to 1000 m/min at the delivery roller pair. The contact pressure at the nip line between two rollers is also very high, in order that it can be ensured that nipping or gripping is still sufficient at these speeds and with these large fibre masses. With high speeds and pressures of this type, the use of aprons is excluded, since a very high amount milling work occurs at the apron, as a result of which the apron would become too hot due to the poor heat dissipation.
The present invention is therefore based on the problem of improving the adjustability of the nip distance to modern high-speed drafting devices (outlet speeds greater than 100 m/min).
This problem is resolved by the features in the independent Patent Claims 1, 11, and 12.
In the Claims and the following Description, mention is made of “bottom roller” and “top roller”. These designations of the two rollers, which are generally conventional in textile technology, are derived in particular from the arrangement of the drafting device, which as a rule is horizontal. The spatial arrangement of the drafting device and of the rollers is, however, absolutely not of significance to the present invention. On the contrary, in particularly preferred application possibilities of the invention, provision is even expressly made for the drafting device to be arranged essentially perpendicularly. Attention is therefore expressly drawn to the fact that the terms “bottom roller” and “top roller” throughout the application are not to be interpreted in respect of their spatial position, restricting them to “top” or “bottom”. The term “bottom roller” can, as a rule, be understood to mean the cylinder of the roller pair. This is for preference made of metal (such as steel). The “top roller” as a rule exhibits an elastic covering (e.g. rubber).
It has been demonstrated that, in particular with high-speed drafting devices, the nip distance can be adjusted simply by an axle being moved, without any disadvantageous effects being determined on the yarn quality or the spinning result. The adjustment of the nip distances is thereby substantially simplified. If only one roller is moved, a cage can be used for the rigidly mounted roller, which does not need to be changed in the event of adjustment. This too simplifies the adjustment. In order to keep the nip or grip forces between the two rollers constant during the adjustment, it is advantageous if the loading force on the nip point can be automatically or manually adjusted. In order for the aprons to exhibit sufficient tension in every position to which they are adjusted, the apron may exhibit a tensioning device at the movably mounted roller. If both rollers have an apron, then both aprons may each exhibit a tensioning device. It would also be conceivable, however, for particularly elastic or extendible aprons to be used, as a result of which no apron tensioning devices would have to be used. And even if the aprons must be replaced because a tensioning device or the elastic properties are not present, a considerable time saving is still achieved, because only one roller needs to be moved.
Advantageous embodiments and forms of the invention are to be found in the dependent Claims.
The invention and the concepts of the invention are explained hereinafter on the basis of the embodiments represented in the Figures. Attention should be expressly drawn to the fact, however, that the invention and the concept of the invention are not restricted to the embodiments shown in the examples. These show:
In
According to the invention as described heretofore, and as represented in particular in
The invention is not restricted to the possibilities and embodiments explicitly mentioned. Rather, these variants are intended to serve as incentives for the person skilled in the art to implement the idea of the invention in the most favourable possible manner. Accordingly, further advantageous applications and combinations can be derived from the embodiments described, which likewise reproduce the concept of the invention and are intended to be protected by this Application. Some of the disclosed features have been described in combination in this Description, and are claimed in combination in the following Claims. It is, however, also conceivable for individual features of this Description to be claimed alone or in another combination in application of the concept of the invention. The Applicants therefore expressly reserve the right to make provision for other combinations in the application of the concept according to the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 04015085.6 | Jun 2004 | EP | regional |
