Measuring and testing – Specimen stress or strain – or testing by stress or strain... – By loading of specimen
Reexamination Certificate
2000-01-20
2001-09-18
Noori, Max (Department: 2855)
Measuring and testing
Specimen stress or strain, or testing by stress or strain...
By loading of specimen
C073S158000
Reexamination Certificate
active
06289742
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for damage detection for the rope sheath of a synthetic fiber rope.
A synthetic fiber rope is a textile product made from rope threads of natural or chemical fibers, the rope being manufactured by twisting or otherwise forming, by laying in two or more stages with or without sheathing, or by braiding. The rope sheath protectively surrounds the rope structure of so-called synthetic fiber strands and, in the case of driven ropes, creates the necessary tractive capacity. It consists preferably of abrasion-resistant synthetic material, and is connected to the outermost layer of strands by adhesion and/or direct mechanical means. Either the rope sheath surrounds the rope in its entirety, or the outermost rope strands are each surrounded by a sheath of synthetic material and these together form the rope sheath. Especially when the ropes run over pulleys, and/or are driven, the rope sheath is subject to high abrasive wear.
The European patent 0 731 209 shows that a sheathed synthetic fiber rope is known as a suspension element for elevators. To ascertain the state of wear of the rope sheath on this driving rope, the rope sheath has different colors arranged coaxially. At an appropriate amount of wear of the sheath, the underlying color becomes visible, which is then taken to indicate the presence of advanced wear of the rope. This indication of damage has proved its value in relation to effects of wear in the rope sheath, but it is of only limited suitability for the reliable detection of localized damage due, for example, to unintentional contact with sharp edges or the like.
SUMMARY OF THE INVENTION
The problem therefore presents itself of specifying a damage detection device for a rope sheath that reliably detects damage to the rope sheath irrespective of the cause of the damage. This problem is solved by the present invention that concerns an apparatus and a method for the detection of damage to the rope sheath of a synthetic fiber rope. As a result of a breaking element inserted in the rope sheath, permanent monitoring of the rope sheath by measurement is possible. For this purpose, a signal is transmitted through the breaking element over a specific length of rope. If this connection is broken, the rope sheath has been damaged from the outside. By monitoring in real time, visual inspection only becomes necessary when the monitoring device detects damage to the rope sheath.
The breaking element can take the form of an electric conductor, an optical fiber cable, or the like. Of importance for the selection of the conducting material used for this purpose is a fatigue strength under reverse bending stress which at least matches that of the rope construction so that material failure due to operation is ruled out.
The breaking element can, for example, be constructed as an electric conductor in the form of a carbon fiber or metal wire through which a control signal is sent. If the conducting connection is cut off, no signal is transmitted, and this can be indicated in a suitable manner.
In combination with a monitoring device, damage to the rope sheath can be detected by the control, and appropriate measures to ensure safe operation of the elevator can be initiated without delay.
The breaking element is preferably wrapped around the entire rope, or the strands of the outer layer, and covered by the rope sheath, which is preferably applied by an extrusion process. Further, with an embodiment having a two-layered rope sheath, the breaking element can be positioned on the inner layer of the rope sheath and covered by the second layer of the rope sheath. In this way, the breaking element is completely embedded in the rope sheath and additional lateral forces acting on the synthetic fiber strands as the rope runs over pulleys are avoided.
In another preferred embodiment, several breaking elements are embedded in the rope sheath around the rope parallel to the strands and/or in the direction of the length of the rope. This has the advantage of the rope sheath being monitored over practically its entire surface area with regard to mechanical damage taking place from outside.
Furthermore, embodiments of the invention in which the breaking element is made from high strength material afford the additional advantage of strengthening or reinforcing the rope sheath. This can be used to improve the rope's fatigue strength under reverse bending stress as well as its abrasive wear behavior.
REFERENCES:
patent: 5015859 (1991-05-01), Uejio
patent: 5131064 (1992-07-01), Arroyo et al.
patent: 5605035 (1997-02-01), Pethrick et al.
patent: 5834942 (1998-11-01), De Angelis
patent: 684029 (1967-01-01), None
patent: 0 731 209 (1996-09-01), None
Inventio AG
MacMillan Sobanski & Todd LLC
Noori Max
LandOfFree
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