|Title of Invention||
A SYNTHETIC FIBER ROPE AND A METHOD FOR MANUFACTURING THE SAME
|Abstract||The present invention relates to a synthetic fiber rope and a method for manufacturing the same and an elevator installation comprising the same having load- bearing strands of bonded synthetic fibers, an outermost layer of the strands being laid on a rope core made up of load-bearing synthetic fiber strands laid together in layers, the improvement comprising: a coating surrounding at least the load-bearing synthetic fiber strands of the outermost layer of strands forming a protective layer about each of the strands individually, said coating being applied as a liquid to the strands prior to laying the strands in the outermost layer of strands of the rope and including in said coating admixtures of UV stabilizers and additives for protection against abrasion and environmental influences damaging to the rope, said outermost layer of strands forming a sheathless outer surface of the rope.|
Sheathless Synthetic Fiber Rope
The invention relates to a synthetic fiber rope , preferably of aromatic polyamide, comprising a coating according to the preamble to Claim 1.
Ropes are especially in conveying technology, for example such as on elevators, in crane construction, and in open-pit mining, moving ropes are an important element of machinery and subject to heavy use. An especially complex aspect is the loading of driven ropes, for example as they are used in elevator construction and for suspended cable cars. In these instances the lengths of rope needed are large, and considerations of energy lead to the demand for smallest possible masses. High-tensile synthetic fiber ropes, for example of aromatic polyamides or aramides with highly oriented molecule chains, fulfil these requirements better than conventional steel ropes. However, materials such as aramides are particularly sensitive to ultraviolet (UV) light, and environments having an oxidizing or reducing effect, which cause the breaking stress and work capacity to be diminished. For this reason, aramide ropes usually are covered with a sheath or braid of material which is stable to light.
For example, from the applicant's EP 0 672 781 Al the use has become known of such sheathed synthetic fiber ropes for the suspension elements of elevator installations, so as to connect the car frame of a car which is guided in an elevator hoistway to a counterweight. To raise and lower the car and the counterweight, the rope runs over a traction sheave which is driven by a drive motor. The drive torque is transferred by friction to the section of rope which at any moment is lying in the angle of wrap.
There, instead of there being a sheath surrounding the entire covering layer of strands, each individual strand of
this layer is given a seamless extruded sneacn or synthetic material, preferably polyurethane or polyamide, all of these together serving as a protection against abrasion of the rope, and ensuring the desired coefficient of friction on the traction sheave.
There, the adhesive forces between the sheaths of synthetic material and the outermost layer of synthetic fiber strands are achieved by the sheath of synthetic material being extruded on under pressure, so that all interstices between the strands are filled, and a form-fit with a large area of adhesion is created. Under certain conditions, however, the transverse forces which arise when the rope is loaded can cause displacement or piling-up of the synthetic sheath. Such changes in the rope are undesirable, as they could lead to failure of the rope. However, using the extrusion process to apply to the strands the sheath needed to create the necessary adhesive forces between the strands and the sheath is expensive.
For this reason, the objective of the invention is to reduce the cost of producing a synthetic fiber rope, while ensuring an unchanged high level of functionality.
According to the invention, this objective is fulfilled by means of a synthetic fiber rope of the type mentioned at the outset, with the characteristics stated in Claim 1.
Extensive tests by the applicant have shown that instead of an extruded protective sheath as hitherto, lasting assurance of reliable protection against UV, as well as adequate resistance of the rope to abrasion, can be achieved by only coating the synthetic fiber strands in the outermost layer of strands with liquid containing UV stabilizers and other additives as protection against abrasion and environmental influences damaging to the rope.
The advantages resulting from the invention consist of a lasting bond of the coating to the synthetic fiber strands of the outermost layer of strands, because the material of the coating and of the matrix binding the synthetic fibers of the strands is the same. By simply admixing appropriate additives the functionality can be easily extended to the entire lifetime of fiber ropes. The coating according to the invention does not form pile-ups, nor can it be displaced on the synthetic fiber strands. Manufacture of the coating takes place to a large extent without additional expense for tools and equipment, and is simple and inexpensive. Taking large-series manufactured conventional synthetic fiber strands as the starting point, the synthetic fiber strands for the outermost layer of fiber strands have only to be drawn through an impregnating bath, which is present in any case, to form the coating according to the' invention. The thickness of the coating can be adjusted via the time spent by the synthetic fiber strands in the impregnating bath. Furthermore, the coating process can be repeated an unlimited number of times.
A particularly abrasion-resistant embodiment of the coating is achieved by adding short fibers, consisting for example of aramide, to the impregnating bath.
Further advantageous embodiments of the invention are stated in the additional dependent claims.
A preferred exemplary embodiment of the invention with impregnating substance in liquid form is described below by reference to a drawing showing a cross-sectional view of a rope 1 composed of sixteen strands. A core strand 2 has helically laid around it five identical strands 3 with which five thicker strands 4, alternating with five thinner strands 5, are laid in parallel lay to form a covering layer 6. The load-bearing strands 2, 4, 5 used for the rope
1 shown are twisted or laid from individual bundles of aramide fibers 7.
The strands 2, 3, 4 and 5 consist essentially of aramide threads 8, which are helically bonded in a matrix of polyurethane. For laying or twisting, the aramide threads 8 are treated with a protective impregnating substance, for example with polyurethane solution. The proportion of polyurethane in each strand 2, 4, 5 is a codeterminant of the fatigue strength under reverse bending stress of the rope 1. The higher the proportion of polyurethane, the higher the reverse bending performance. As the proportion of polyurethane increases, the fill factor of the entire rope 1 decreases, and with it the load-bearing capacity and elongation behavior of the rope 1. Depending on the rope properties desired, the proportion of polyurethane for impregnation of the strands 2, 4, 5 can be, for example, between ten and sixty percent.
By way of example, in the embodiment illustrated, seven aramide threads 8 are joined together and bonded into a filament 7 by means of impregnation. In this way, the impregnation forms a thin protective layer 9 around each individual filament 7. Seven of the filaments 7 are laid together helically into a strand 2, 3, 4, 5. In the factual embodiment, the filaments 7 do not have the circular shape shown in the drawing, but are adapted to the surface of adjacent filaments and the strands. To this extent, the structure of all the strands 2, 3, 4, 5 used in the exemplary embodiment is, as a general rule, identical, but the number of twists per meter can vary between the various layers of strands, and between the strands having various diameters.
According to the invention, each of the thick strands 4 and thin strands 5 laid in the covering layer 6 is surrounded by an additional protective layer 10 of impregnating
substance. It is advantageous for this protective layer to be formed on the surface of the thick strands 4 and thin strands 5 by their being given an additional soaking in a bath of impregnating substance in a draw-through process. In addition to polyurethane, the impregnating substance also contains as additives UV stabilizers, preferably silicon crystals, and oxidation and reduction blockers. Adding short fibers, preferably of aramide, gives the protective layer 10 improved abrasion resistance.
Here, the thickness 11 of the protective layer 10 around the individual strands 4, 5 is 0.2 mm; however, according to the invention, it can be selected in the range between 0.1 and 1 mm depending on the protective effect desired. The protective layer 10 functions as a protection against abrasion between the thick strands 4 and the thin strands 5 of the covering layer 6, and bonded together with all the strands 4, 5 of the covering layer 6 forms a coating for the rope 1 which is as effective as it is inexpensive to manufacture. Because of this, an additional rope sheath of synthetic material can be dispensed with. According to the invention, strands 4, 5 coated with a protective coating 10 can be manufactured in advance as a semi-finished product, and then processed further as required using conventional rope-making machinery, which significantly reduces the manufacturing costs of the aramide fiber rope 1.
Instead of an impregnating substance, a different liquid with adhesive properties can also be applied to the rope.
As well as being used purely as a suspension rope, the rope can be used in a wide range of equipment for handling materials, examples being elevators, hoisting gears in mines, building cranes, indoor cranes, ship's cranes, aerial cableways, and ski lifts, as well as a means of traction on escalators. The drive can be applied by friction on traction sheaves or Koepe sheaves, or by the
rope being wound on round drums. A hauling (tope is to be understood as a moving, driven rope, which is sometimes also referred to as a traction or suspension rope.
1. Coating for a rope with load-bearing strands (2, 2, 5)
of bonded synthetic fibers (8), preferably polyamide
fibers, these load-bearing synthetic fiber strands (2,
3, 5) preferably being laid in an outermost layer of
strands (6) on a rope core made up of load-bearing
synthetic fiber strands (2, 3) laid together in layers,
the coating (10) surrounding at least the load-bearing
synthetic fiber strands (4, 5) of the outermost layer
of strands (6),
characterized in that
the coating (10) is made from a liquid with admixtures of UV stabilizers and other additives for protection against abrasion and environmental influences damaging to the rope.
2. Coating for a synthetic rope according to Claim 1,
characterized in that
the liquid consists of an impregnating substance for bonding the synthetic fibers (8).
3. Coating for a synthetic rope according to Claim 1,
characterized in that
the impregnating substance contains short fibers to give protection against abrasion.
4. Coating for a synthetic rope according to Claim 1,
characterized in that
the impregnating substance contains oxidation and reduction blockers.
5. Coating for a synthetic rope according to Claim 1,
characterized in that
the impregnating substance consists of polyurethane solution.
6. Coating for a synthetic rope according to Claim 1,
characterized in that
the coating (10) has a layer thickness (11) of between 0.1 and 1 mm.
7. Process for manufacturing a coating (10) for a
synthetic rope (1) of bundled synthetic fibers (8),
preferably polyamide fibers, which by means of an
impregnating substance are bonded into load-bearing
synthetic fiber strands (2, 3, 4, 5), these load-
bearing synthetic fiber strands (4, 5) being laid on a
rope core made up of load-bearing synthetic fiber
strands (2, 3) laid together in layers, the coating
(10) surrounding at least the load-bearing synthetic
fiber strands (4, 5) of the outermost layer of strands
the synthetic fiber strands (4, 5) of the outermost layer of strands (6) are coated by soaking with impregnating substance which contains additives to give protection against abrasion and environmental influences which are damaging to the rope.
8. Process according to Claim 7,
characterized in that
following a first soaking, short strands are applied to the synthetic fiber strands (4, 5) of the outermost layer of strands (6), and the synthetic fiber strands (4, 5) are then coated by being again soaked with impregnating substance.
9. Elevator comprising a synthetic rope with a coating
according to any of the Claims 1 to 6.
10. Coat ing for a rope with load-bearing strands of bonded synthetic fibers, substantially as herein described with reference to the accompanying drawings.
Dated this 5th day of November 1999
|Indian Patent Application Number||1067/MAS/1999|
|PG Journal Number||26/2007|
|Date of Filing||05-Nov-1999|
|Name of Patentee||INVENTIO AG|
|Applicant Address||SEESTRASSE 55, CH-6052 HERGISWIL|
|PCT International Classification Number||002 G 003/36|
|PCT International Application Number||N/A|
|PCT International Filing date|