|Title of Invention||
A TRANSPORT BELT FOR TRANSPORTING A FIBRE STRAND TO BE CONDENSED
|Abstract||A transport belt for transporting a fibre strand to be pneumatically condensed is provided with an air-permeable middle area and with air-permeable border areas. These two areas are made of a woven fabric consisting of thermoplastic filaments, whereby the border areas are made air-impermeable by means of a heating process.|
|Full Text||BACKGROUND AND SUMMARY OF THE INVENTION
A transport belt for transporting a fibre strand to be condensed
The present invention relates to a transport belt for transporting a fibre strand to be pneumatically condensed, comprising an air-permeable middle area designed as a woven fabric consisting of thermoplastic filaments, also comprising air-impermeable border areas, whose edges are treated by a heating process.
When a drafted fibre strand is imparted a spinning twist directly downstream of the front roller pair of a drafting unit, a so-called spinning triangle occurs at the nipping line of the front roller pair. This comes about because the drafted fibre strand leaves the drafting unit having a certain width and is twisted to a thread having a relatively small diameter. The spinning triangle comprises lateral fibres, which are not properly bound into the twisted thread and thus contribute little or nothing to the tensile strength of the spun thread. In recent times, a condensing zone has been arranged downstream of the drafting zone of the drafting unit, which condensing zone is in turn bordered by a nipping line. Only downstream thereof is the thread imparted its spinning twist. The fibres are bundled or condensed in the condensing zone, whereby the fibre strand is so narrow when it leaves the nipping line furthest down-stream that the feared spinning triangle is no longer noticeably disadvantageous. The spun thread is then more even, more tear-resistant and less hairy.
Many various arrangements are known for the purpose of condensing a fibre strand. Many of these arrangement operate with an air-permeable transport belt, which transports a fibre strand to be condensed in a sliding manner over a suction slit. An arrangement of this type is disclosed, for example, in German published patent application 198 37 182. In this publication, among others, a transport belt is described which comprises an air-permeable middle area made of a woven fabric of thermoplastic filaments, as well as an air-impermeable border area on both sides. The edges of the border areas can be reinforced by means of a heating process.
It should be noted at this point that in the terminology of this patent application under the expression ..pneumatic condensing", such arrangements are also included in which, apart from the suction air stream, also other means, for example a transport component aligned against a transversely set suction slit, can also be effective.
It is an object of the present invention to create a new type of transport belt of the above mentioned type for pneumatic condensing of a fibre strand, in which the air-impermeable border areas are designed in a particular way. This object has been achieved in accordance with the present invention in that the air-permeable middle area as well as the air-impermeable border areas are made of a woven fabric, in which the border areas are made air-impermeable by means of a heating process.
While in prior art the method for making the border areas of the transport belt air-impermeable is left open, and while in the case of the known transport belt only the edges of the border areas are reinforced by means of the heating process, the new type of transport belt is based on a woven fabric which is entirely made of thermoplastic filaments, whereby the entire border areas are made air-impermeable by means of a heating process. The air-permeable woven fabric in the middle area is re-formed on its border areas into a sort of smooth foil. The new type of transport belt is hereby given an increased form stability, in particular when, for the purposes of cleaning, it has to be washed at intervals. The narrower air-permeable middle area results in a reduced trash deposit on the transport belt, as only the actual effective area is suctioned and as a consequence no fibre fly or trash can adhere at a result of a suction. The new type of transport belt leads in particular to a longer lifetime.
The transport belt is advantageously seamless in transport direction, which is achieved in that the transport belt is seamlessly woven on a circular loom in the form of tubes. Monofilaments are advantageously provided for the woven
fabric, which have a sufficient stability and a permit a homogenous suction air current.
The border areas of the transport belt can be made air-impermeable in a variety of ways by means of a heating process. In one variation it is provided that the border areas are made air-impermeable by means of welding, for example by means of a correspondingly wide electrode. In a further embodiment, the border areas can be coated with a hot-melt-type adhesive, whereby it is sufficient to coat the transport belt on one surface only, so that the woven structure is maintained on the other surface.
In practice, transport belts having an air-permeable area which measures in width between 0.3 and 0.5 times the width of the transport belt itself have been proven. For example, the air-permeable middle area can have a width of 10 mm, while the transport belt measures 25 mm overall. The air-impermeable border areas then each measure 7.5 mm.
BRIEF DESCRIPTION OF THE DRAWINGS
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:
Figure 1 is a partial intersectional side view of an arrangement for condensing a fibre strand, comprising a transport belt according to the present invention,
Figure 2 is a view in the direction of the arrow II of Figurel of the actual condensing zone, whereby the rollers shown in Figure 1 have been omitted,
Figure 3 greatly enlarged is a cross section of a transport belt according to the present invention,
Figure 4 is a cross section similar to Figure 3 of a further embodiment of the transport belt according to the present invention.
DETAILED DESCRIPTION OF THE DRAWINGS
Of a spinning machine, in particular a ring spinning machine, only the area of an arrangement 1 for condensing a drafted, still twist-free fibre strand 2 is shown in Figures 1 and 2. The arrangement 1 is located directly downstream of a drafting unit 3, of which only the front roller pair 4 as well as an apron roller pair 5 having a lower apron 6 and an upper apron 7 arranged in transport direction A upstream of the front roller pair 4 are shown. The front roller pair 4 comprises a driven front bottom cylinder 8 as well as a front pressure roller 9 pressed flexibly thereagainst. The front roller pair 4 defines a front nipping line 10, which forms the end of the drafting zone of the drafting unit 3.
In the drafting unit 3, a sliver or a roving 11 is drafted in the known way to the desired degree of fineness in transport direction A. This drafting process ends at the front nipping line 10, and from this line on a drafted, but still twist-free fibre strand 2 is present In order to avoid the known and disadvantageous spinning triangle, the ftire strand 2 is condensed directly downstream of the front nipping line 10 in a condensing zone 12. The arrangement 1 provided for condensing comprises an air-permeable transport belt 13, which transports the fibre strand 2 to be condensed through the condensing zone 12. The arrangement 1 also comprises a suction channel 14, which is designed as a hollow profile with prevailing low pressure and which extends over a plurality of spinning stations. The suction channel 14, for the purpose of guiding the transport belt 13 is, on is outer contour facing the condensing zone 12, designed as a sliding surface 15.
A suction slit 16 is located in the sliding surface 15, which suction slit 16 is arranged slightly transversely to the direction of motion B of the transport belt 13, so that in relation to tfie fibre strand 2 to be condensed, the suction slit 16 comprises a fibre guiding edge 17. The fibre strand 2 travels along this fibre guiding edge 17 during condensing, whereby the fibres located in the fibre strand 2 are bundled or condensed transversely to the direction of motion B of the transport belt 13, whereby the fibre strand 2 is rolled in somewhat.
The suction channel 14 is connected via a vacuum connection 18, which is located at a distance to the suction slit 16, to a vacuum source (not shown). If the suction channel 14 extends over a plurality of spinning points, only one vacuum connection 18 need be provided per suction channel 14.
The condensing zone 12 is limited on its downstream side by a nipping roller 19, which presses the fibre strand 2 and the transport belt 13 to the sliding surface 15 while defining a delivery nipping line 20, which acts as a twist block in relation to the spinning twist to be imparted. The nipping roller 19 drives the transport belt 13 and is in turn driven via a transfer wheel 21 by the front pressure roller 9.
Downstream of the delivery nipping line 20, the produced thread 22 receives a spinning twist, as the thread 22 is fed in delivery direction B to a twist element (not shown), for example a ring spindle. The delivery nipping line 20 serves as a twist block to the spinning twist, so that the spinning twist cannot retroact back into the condensing zone 12.
The transport belt 13 is tensioned by means of a tensioning element 23 on the side facing away from the suction slit 16, which tensioning element 23 can, for example be designed as a stationary rod or also as a guiding roller. The tensioning element 23 is arranged hereby in such a way that the transport belt 13 is disposed with a slight pressure on the front bottom cylinder 8. Because the transport belt 13 and the front bottom cylinder 8 rotate in opposite directions at the line of contact, the transport belt 13 is hereby cleaned of any fibre fly which has adhered thereto.
As can be seen from Figure 2, the initial area 24 of the suction slit 16 has an extension, which serves to permit the suction slit 16 to seize the fibre strand 2 traversing slightly in transverse direction. The traverse movement serves in particular to ensure that the front pressure roller 9 has a longer lifetime.
With the aid of the greatly enlarged Figure 3, the heart of the arrangement 1, namely the air-permeable transport belt 13 is described in more detail below.
In Figure 3, the air-permeable middle area 25 of a transport belt 13 can be seen in greatly enlarged dimensions, which middle area 25 is formed by a woven material of thermoplastic filaments. On both sides of this middle area 25 there is an air-impermeable border area 26 and 27, the edges of which are denoted by the numbers 28 and 29.
The entire transport belt 13 consists in the making initially of a woven material, as can be seen in the middle area 25. The border areas 26 and 27 of this woven material, however are made subsequently air-impermeable by means of a heating process, so that the mesh of the woven material is thus closed. In this way, the smoother border areas 26 and 27 form, which ensure the above mentioned advantageous features for the transport belt 13.
When the transport belt 13 is woven in the form of tubes on a circular loom, it can be completely seamless in its finished state.
The heating process can be carried out in a variety of ways. According to Figure 3, the border areas 26 and 27 are rendered air-impermeable using a correspondingly wide electrode by means of welding. The transport belt 13, having a width B of, for example 25 mm, comprises then a middle air-permeable area 25 having, for example, a width M of 10 mm, as well as two air-impermeable border areas 26 and 27 each having a width R1 or R2 of 7.5 mm.
In the embodiment according to Figure 4, the same air-permeable middle area 25 having a width M is present, which middle area 25 consists of woven thermoplastic monofilaments. It can be further seen from Figure 4 that the woven structure on the underside extends along the entire width B of the transport belt 13. Deviating from the embodiment in Figure 3, it is provided in Figure 4 that the border areas 30 and 31 are provided on the upper side with a hot-melt type adhesive 32 or 33. Thus the perforation of the woven material is, in this case, not closed on the underside, although the coating from the upper side also renders the border areas 32 and 33 air-impermeable.
1. A transport belt for transporting a fibre strand to be pneumatically condensed, comprising an air-permeable middle area designed as a woven fabric consisting of thermoplastic filaments, also comprising air-impermeable border areas, whose edges are treated by a heating process, characterized in that the air-permeable middle area (25) as well as the air-impermeable border areas (26,27;30,31) are made of one and the same woven material, in which the border areas (26,27;30,31) are rendered air-impermeable by means of a heating process.
2. A transport belt according to claim 1, wherein the transport belt 1 is seamless in transport direction (A).
3. A transport belt according to claims 1 or 2, wherein monfilaments are provided for the woven fabric.
4. A transport belt according to any one of the claims 1 to 3, wherein the border areas (26,27) are rendered air-impermeable by means of welding.
5. A transport belt according to any one of the claims 1 to 3, wherein the border areas (30,31) are coated with a hot-melt type adhesive (32,33).
6. A transport belt according to any one of the claims 1 to 5, wherein the width (M) of the air-permeable area (25) measures between 0.3 and 0.5 times the width (B) of the transport belt (13).
A transport belt for transporting a fibre strand to be pneumatically condensed is provided with an air-permeable middle area and with air-permeable border areas. These two areas are made of a woven fabric consisting of thermoplastic filaments, whereby the border areas are made air-impermeable by means of a heating process.
|Indian Patent Application Number||248/KOL/2004|
|PG Journal Number||27/2011|
|Date of Filing||14-May-2004|
|Name of Patentee||MASCHINENFABRIK RIETER AG.|
|Applicant Address||KLOSTERSTRASSE 20, 8406 WINTERTHUR|
|PCT International Classification Number||D01H1/22,5/26,5/72,5/86;B29D29/06|
|PCT International Application Number||N/A|
|PCT International Filing date|