Synthetic fiber rope

Details Synthetic fiber rope Synthetic fiber rope

1999-10-21

2001-11-20

Lillis, Eileen D. (Department: 3652)

Elevator, industrial lift truck, or stationary lift for vehicle

Having specific load support drive-means or its control

Includes linking support cable in drive-means

C187S411000, C187S251000, C057S204000, C057S235000, C057S230000

Reexamination Certificate

active

06318504

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a synthetic fiber rope, preferably of aromatic polyamide material.
Especially in materials handling technology, for example on elevators, in crane construction, and in open-pit mining, etc., ropes are an important element of machinery and subject to heavy use. An especially complex aspect is the loading of driven or over pulleys deflected ropes, for example as they are used in elevator construction.
Specifically, on elevator installations 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.
Specifically, ropes constructed of aramide fibers have a substantially higher lifting capacity than conventional steel ropes of the same cross section, and only between one fifth and one sixth of the specific gravity. However, the atomic structure of aramide fiber causes it to have a low ultimate elongation and a low shear strength.
Such an aramide fiber rope with parallel lay is known, for example, from European patent document EP 0 672 781 Al. There, between the outermost and inner layers of strands there is an intersheath which prevents contact between the strands of different layers and thereby reduces the wear due to their rubbing against each other. The aramide rope described so far has satisfactory values of service life, resistance to abrasion, and fatigue strength under reversed bending stresses. However, when loaded under tension the twisted stranded synthetic fiber rope has a tendency to rotate about its longitudinal axis and/or untwine. The undesirable untwining of the stranded rope can lead to an unevenly distributed loading of the strands of different strand length over the cross section of the rope and thereby to a reduction in the breaking load of the rope or even to failure of the rope.
SUMMARY OF THE INVENTION
An objective of the present invention is to avoid the disadvantages of the known synthetic fiber rope and to specify a permanently dependable twisted synthetic fiber rope.
The advantages resulting from the present invention relate to the fact that the intersheath, by having sheath surfaces adapted to the contours of adjacent layers of strands, provides a larger area of contact with the strands and thereby also completely bridges the interstices between the strands of the layers of strands adjacent to it. The tight bond between inner and outer layers of strands results in a higher torsional rigidity of the stranded rope. This prevents a loaded rope with contoured intersheath according to the invention from twisting irrespective of the type of torque acting on it. With the invention there is therefore a greater supporting and/or load-bearing area of sheath available even when the rope is in the loaded state. This in turn results in a homogenized transfer of torque over the entire circumferential area of the sheath to the interior of the rope. As a result, the constrictive force of the covering layer of strands no longer acts mainly as a transverse force on the highest points of individual strands, but is spread widely, i.e. with reduced pressure, over the entire circumferential surface of the sheath of the adjacent layers of strands.
With appropriately selected elasticity, the intersheath can absorb differing longitudinal movements of adjacent strands without the strands moving relative to the intersheath, from which advantages are derived in relation to the flexibility of the rope and its behavior under reversed bending.


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