TECHNOLOGY NEWS:
Central tube strander: a new concept of machine
Cortinovis SpA, Italy, has launched a new concept of central tube strander at wire Düsseldorf, capable of stranding up to 6 wires at 700rpm in a continuous operation (without deadtimes for loading reels, because the wires are fed during the operation). Acting as well as a screening and armouring machine for fibre optics or copper telecomunication cables, the machine has been designed to strand up to 61 conductors in just one step, shaping them in the regular formation of 1+6+12+18+24 to produce electrical power cables. The machine can be installed either in series or in tandem. For instance, a multilayer 1+6+12+18+24 cable can be produced either in subsequent passages on a 24-bobbin machine or in just one passage on four sections of 6/ 12/ 18/ 24 bobbins respectively, operating either in tandem or in series.
As for a classic tubular strander, the external tube of the new Cortinovis central tube strander constitutes the supporting frame (as it carries the wire bobbins) and the stranding body (as it drives in rotation the wires coming from its inside and running along linear peripheral paths). With the new machine, the threading is equally easy and the wire deviations are equally smooth. The bobbins are put on the same axis of the general machine and are directly hold by the tube by means of central hollow shafts that are fixed by sturdy flanges. The possibility of using central hollow shafts for all the bobbins, all along the machine axis, allows the passage, undisturbed by the rotation of the machine, of a central core cable already shaped. The feeding is directly made from coils or stempacks. Each bobbin is driven by a dedicated, independent friction clutched device to wound the wire directly from its feeding coil or stempack. The wire runs through a window of the tube, stopped in a suitable position. In addition, the wire-winding radius, and therefore the wire stress, is highly reduced.
The possibility of using central hollow shafts for all the bobbins also allows to introduce a steady concentric hollow shaft all along the machine axis to permit the passage of static feeding paths to every bobbin. A traversing distribution device that alternatively feeds one of the two bobbins serves each couple of faced. During the feeding of one bobbin, the second one is unwound and supplies the wire to be stranded. The wire flows on one series of bobbins during the outflow of the stranding wire from the other series: there is just one stop for the inversion of the wires connection. The machine is nearly always in operation, without dead times: there is a continuous flow of feeding wires into the machine and of produced strand out of the machine.
Cortinovis’ new central tube strander has been designed to provide better quality product through an easier wire path with lesser deviations, lesser centrifugal force (lower wire pull of extraction, a wider loading of large diameter bobbins for a significantly lower number of edge invertions and pull-shoots, as well as a single bobbin regulation of the pull that compensates every winding irregularity. This new concept of central tube strander also features the following advantages:
- The stranding frame, being of cylindrical form revolving on itself, can reach very high-rotation speeds (700 rpm) and productivity (700 lays per minute);
- The stranding rotation produces at the same time the feeding of the conductors to be stranded, so that the machine operates continuously and without dead times for the loading of the reels containing the feed conductors (a task never performed before in a screening and armouring machine).
Photo: Cortinovis new central tube strander
Photo: A multilayer 1+6+12+18+24 cable can be produced in subsequent passages on a 24-bobbin machine version
Photo: Scheme showing the double feeding principle on the new central tube strander
Company: |
Cortinovis SpA |
Country: |
Italy |
Fax: |
+39 035 312523 |
Email: |
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Website: |