Textiles: spinning – twisting – and twining – Strand structure – Covered or wrapped
Patent
1996-04-22
1998-08-25
Stryjewski, William
Textiles: spinning, twisting, and twining
Strand structure
Covered or wrapped
57216, D02G 336
Patent
active
057972540
DESCRIPTION:
BRIEF SUMMARY
This invention relates to solid polymeric cores for wire ropes.
Traditionally the core or central member of a stranded wire rope was manufactured by spinning together tows of natural fibre such as sisal, usually in the form of a 3 (or 4) strand fibre rope. More recently continuous yarns of man-made fibres such as polypropylene have been substituted for the natural fibre staple, but still retaining the (3 or 4) stranded lay-up, which has the disadvantage of providing irregular support to the surrounding steel strands. In particular GB-A-1 092 321 discloses a core which consists of polyamide, polyester, or polypropylene monofilaments helically twisted together and which has been compacted under tension at a temperature above the softening point of the monofilaments.
The disadvantage of irregular support can be overcome by means of an earlier invention of the applicant, which is described in GB-A- 2 219 014 and GB-A-2 269 400, wherein a wire rope core is provided with an externally fluted surface to closely mate with the internal surfaces of the rope. The said fluted core is typically produced in two manufacturing operations using a cross-head extruder with a rotating die to form the fluted cross-sectional profile. Whilst this invention has proved very successful for medium sized ropes and has been shown to offer a product with superior service performance, it is recognised that the method is less attractive for small diameter ropes which are typically manufactured on high speed machinery. Specifically, the manufacturing method used for the fluted core is restrictive both in terms of production speed and the available material properties. It would be desirable to be able to offer a solution to these problems and provide a new type of high performance core for small diameter wire ropes, e.g. elevator ropes.
In one aspect the present invention provides a solid polymeric core for wire ropes which possesses an orientated structure in which the crystals are elongated and orientated in the axial direction.
In another aspect the invention provides a solid polymeric core for wire ropes which possesses an axially orientated structure and is polygonally shaped to correspond with the internal geometry of the rope.
In a further aspect the invention provides a solid polymeric core for wire ropes which has a structure comprising crystals orientated in two directions, that is in a direction transverse to the axis of the core as well as in the axial direction.
The core is preferably of unitary or one-piece construction, but alternative constructions comprising a plurality of elements are possible. For example, the solid elongate body may be of coaxial construction, being formed from successive layers of polymeric material (which may differ from layer to layer). In another embodiment the body may be an assembly of mutually parallel polymeric elements. In this case the number (n) of elements is preferably directly related to the number (m) of strands which are to enclose the core (e.g. n=m/2, n=m, or n=m+1).
The invention also provides a method of producing the said core in a single- or multi-stage operation using a controlled means of forming the core whilst in its solid state.
The invention further provides wire rope containing a solid polymeric core of unitary or multi-element construction in which the structure of the core material is preferentially orientated in a substantially axial direction. Preferably the core is externally profiled to correspond with the internal geometry of the rope. The wire rope may, for example, comprise 6 or 8 outer strands over the said core. The core may contribute significantly (e.g. 5%, up to 10%, or more) to the load bearing capability of the rope.
The invention will be described further, by way of example only, with reference to the accompanying drawings, in which:
FIG. 1 is a schematic elevation of apparatus for manufacturing a core for wire rope;
FIG. 2 is an axial cross-section through a first embodiment of forming device;
FIG. 2a is an end view of the forming device of FIG. 2;
FIG. 3 i
REFERENCES:
patent: 1183487 (1916-05-01), Parker
patent: 4348350 (1982-09-01), Meier et al.
patent: 4950151 (1990-08-01), Zachariadas
Bridon PLC
Stryjewski William
LandOfFree
High strength core for wire ropes does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with High strength core for wire ropes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and High strength core for wire ropes will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-29548