Textiles: spinning – twisting – and twining – Apparatus and processes – Unitary multiple twist devices
Patent
1983-10-20
1985-10-29
Petrakes, John
Textiles: spinning, twisting, and twining
Apparatus and processes
Unitary multiple twist devices
57 9, 57 5852, 57 5859, 57 5865, 57311, D07B 310
Patent
active
045493944
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a stranding device for stranding machines, particularly a pre-twist and drafting device as an advance ancillary device for single and multiple rope-lay machines, with a rotatably-driven rotor support frame and a driven drafting wheel mounted on the rotor support frame, transversely of the rotational and longitudinal axes thereof, in which the wire rope components are supplied to a stranding entry station in the longitudinal axis of the rotor support frame and the wire rope is guided at the rotor support frame to the drafting wheel and, after passing round it, is guided from the rotor support frame along the longitudinal axis.
Conventional single-lay machines give the advantage of the highest attainable stranding quality, although they are much too slow in comparison with current double-lay machines, however. The known double-lay machines are preferable to single-lay machines, however, substantially only as regards their production rate. The very common three-layer or multi-layer strands of 16 or more bright wires can be prepared in a single stage very much more carefully, uniformly and thinly and in particular with substantially smaller variation and in the external diameter than in a double-lay operation. The economical handling of single-lay operation avoids excessive stretching, which would lead to hardening of the wires and thus a loss of electrical conductivity. The substantially smaller strand diameter tolerances permit considerably smaller covering thicknesses, on insulation with plastics materials or rubber. Depending upon the construction of the strands-governed by the number of wires and the wire diameter-the increased cost of insulation material in double-lay operation, compared to single-lay operation, amounts in practical measured cases to from 19.5% up to a maximum of 27.8% (see "Drahwelt" 7--1977, p 271).
It is now known that the quality of stranding in double-lay machines is particularly increased if, before passing into the double-lay rotor frame, a pre-twist device is provided, which drives the strands directly with the desired velocity of two draftings per double-lay rotation.
If this pre-twist device is constructed at the same time as a drafting device, it allows the tensile force to serve to overcome the total resistance of all braking tensions in the single-lay bobbins. The strands further guided into the double-lay machine only for winding are thus considerably relieved from stresses.
A stranding device particularly suitable for the manufacture of multi-layer high-voltage cable as a pre-twist and drafting device must therefore possible, in order to achieve significant savings in insulating material, economically of material that any excess stretching and hardening of the stranded product is prevented and thus loss of electrical conductivity of the high-voltage cable, for instance, is avoided.
The main point is not a strand pre-twisted in a single-lay operation, without partial intermediate stranding by a double-lay machine, is led through to the coiling bobbin. What is important is that, in the single-lay pre-twist device, the entire cable (as a doubled single-lay) is withdrawn, so that, for the entire inner to outer wire layers, the correct wire lengths required for the doubled and prepared wire cable are drawn off. That only the strands produced on double-lay machines are basically not so uniform and so thin leads to the fact that, in the double-lay machine without a pre-twist device, at the entry to the machine, it is only for the first and thus still single rope strand that the appropriate wire lengths can be drawn off. The wire lengths being introduced, firstly suitable from layer to layer, i.e. correctly adjusted, no longer totally serve for the subsequent second-lay stage, since then the inner wire layers have relatively too large an excess length in comparison with the outer layers. The increasing relative excess length, from the outer to the inner layers in multi-layer cables, that is relative to the core wire, tends to form loops and thus leads to v
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patent: 3413793 (1968-12-01), Stine
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Petrakes John
Striker Michael J.
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