Ladder wire rope refers to the traction wire rope. The traction rope bears the entire weight of the elevator and bends in one direction or alternately around the traction sheave, guide pulley or reverse sheave during the operation of the elevator. The steel wire rope also bears high specific pressure in the rope groove. Therefore, elevator wire ropes are required to have high strength, flexible design and wear-resistant design.
1. Types and specifications of elevator wire ropes Elevator wire ropes are generally circular strand structures, mainly composed of steel wires, rope strands and rope cores. Steel wire is the basic component of steel wire rope, which requires high strength and tough design. Steel wire rope strands are twisted from steel wire, usually 6-8 strands. The core of the rope is usually made of fiber sisal or olefin-based synthetic fibers.
2. Selection and calculation of wire rope
3. Factors affecting the life of wire ropes
a. External factors: tensile load, radius of curvature, groove shape, traction sheave groove material, corrosion, etc.
b. Internal factors: The design capacity of the steel wire, the diameter of the steel wire, the twisting type of the steel wire, etc.
4. Wire rope scrapping standards The operating life of the wire rope on the traction sheave will be limited by wear and alternating stress of the wire. In most cases, replacement should be determined as long as obvious external wire breakage is observed.
In order to ensure the normal operation of the elevator, the main criterion for scrapping the wire rope is to check the number of visible broken wires on a pre-selected length, and the check length is 6d or 30d (d wire rope diameter). When the number of visible broken wires in the wire rope exceeds the specified number, it must be replaced.
For 6-strand and 8-strand steel wire ropes, broken wires mainly occur on the surface. The situation is different for multi-layer wire ropes. Most of the broken wires in this type of wire rope occur internally, so they are "invisible" breaks. In addition, when the steel wire rope has broken wires at the rope end or local accumulation of broken wires, scrapping should also be considered. When the diameter of the wire rope is reduced by more than 7% relative to the nominal diameter, the wire rope should be scrapped even if no broken wire is found.
5. Traction rope termination device The design of the traction rope termination device should take into account: it is conducive to the adjustment of the wire rope tension. At least one end of the termination device is adjustable; the mechanical strength of the joint between the wire rope and the termination device should be at least Withstand 80% of the minimum breaking load of the wire rope.
When the roping ratio of the steel wire rope is 1:1, one end of the steel wire rope is fixed on the upper beam of the car frame, and the other end is connected to the counterweight frame. In other cases, the wire rope must go around the reverse sheave installed on the upper beam of the car frame and the counterweight frame. The suspension of each wire rope must be relatively independent. The forms of wire rope termination devices are: a. Taper sleeve type b. Self-locking wedge type c. Rope clamp
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