Textiles: spinning – twisting – and twining – Apparatus and processes – Unitary multiple twist devices
Patent
1982-09-09
1984-12-04
Watkins, Donald
Textiles: spinning, twisting, and twining
Apparatus and processes
Unitary multiple twist devices
57115, 57 5863, D07B 312, D01H 786
Patent
active
044856148
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to an annular or closed loop rotatable frame or "flyer" such as is used in a stranding machine of the type, in which two or more wires, fibres or strands are stranded to a cable, e.g. intended for stranding insulated conductors e.g. for the production of cables for telecommunication, the flyer being arranged to rotate around one or more bobbins.
BACKGROUND ART
At a known stranding machine for stranding two or more wires or fibres a flyer is rotatable around a shaft and two or more wire bobbins are suspended within the orbit of the flyer on a suspension device rotatably supported by the flyer shaft and thus not taking part in the rotation of the flyer. From the bobbins the wires are passed down into the hollow shaft of the flyer, where they are stranded to a cable, which is further passed to a tape applicating machine, or to a capstan. In order that the bobbins shall not take part in the rotation of the flyer, the suspension means are constructed and loaded in such a way that their centre of gravity is outside the flyer shaft axis or its elongation, which in addition diverges from the vertical.
Owing to the rotation the flyer is subjected to centrifugal forces that limit the stranding speed. In order to give the flyer better strength against these centrifugal forces, it has been tried to design the flyer as a preferably circular frame. But even for such a frame the rotation speed is limited, depending on the allowable stress of the material and depending on the air resistance of the rotating flyer.
DISCLOSURE OF THE INVENTION
According to the present invention the speed of a flyer constructed as an annular frame can be further increased by journalling the frame in two diametrically opposite points and prestressing the flyer by stretching it at these two points. It will then be prestressed by a bending moment in the plane of the flyer in a direction perpendicular to the centrifugal force produced by the rotation of the flyer. The prestressing force may at most produce the maximum acceptable bending moment in the flyer. When the flyer rotates a bending moment in the opposite direction is developed and may thus be two times the bending moment that can be accepted without prestressing. It has been shown that for a circular flyer and a safety coefficient of 3.5 it is possible to allow a speed of rotation which is 25% higher than without prestressing the flyer.
In order to gain the optimal speed the flyer according to the invention ought to be made as thin as possible and aerodynamically shaped whereby the air resistance and noise decrease, but at the same time having high rigidity and low natural frequency. It is especially preferable to use rings of fibre reinforced plastics, e.g. carbon fibre reinforced epoxy resin with continuously wound fibres in tangential i.e. circumferential direction.
In order to produce the prestressing the flyer is mounted at diametrically opposite points in bearings, that can stand axial forces. Further advantages of the flyer are achieved by embodiments given in the claims.
BRIEF DESCRIPTION OF THE DRAWING AND A PREFERRED EMBODIMENT OF THE
INVENTION
The invention is to be described in more detail referring to the attached drawing in which:
FIG. 1 shows an embodiment with two bobbins inside the flyer,
FIGS. 2 and 3 show in cross section and longitudinal section respectively a flyer of the preferred material, carbon fibre placed in circumferential direction and bound with epoxy resin.
According to FIG. 1 an annular flyer 1 is fastened to a shaft 2 and journalled 3 in a rack 4. The other end of the shaft is equipped with a driving gear 5. Inside the flyer the shaft is extended by a tube 6 on which a stand 9 for the bobbins 10, 11 is journalled, 7, 8. By eccentric suspension of the bobbins or in any other way it is ensured that the centre of gravity of the stand always is below the inclined centre line of the shaft. From the bobbins 10, 11 two wires 12, 13 are passed over pulleys 14, 15 mounted in a socket 16, projecting from the stand 9, t
REFERENCES:
patent: 3793819 (1974-02-01), Madalozzo et al.
patent: 3812666 (1974-05-01), Sarracino
patent: 3945182 (1976-03-01), Dover et al.
patent: 4159618 (1979-07-01), Sokaris
patent: 4302924 (1981-12-01), Faulstich
patent: 4339909 (1982-07-01), Godderidge
patent: 4384447 (1983-05-01), Faulstich
AB Kompositprodukter S.K.-F.M.
Watkins Donald
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