There are two kinds of static and dynamic loads for manipulating the wire rope in work, but the main factor affecting the service life of the wire rope is the static load. For the sake of simplicity, only the static load is used for practical calculation.
Selection of diameter of manipulation wire rope
In order to increase the strength of the elevator rope and extend its service life, the diameter of the elevator rope is usually selected according to the formula D / d≥40, where d is the diameter of the rope not less than 8mm; D is the diameter of the traction sheave;
Calculation of safety factor
K static in the type-safety factor of the elevator rope;
SP—breaking tensile force of elevator wire rope;
M—the magnification determined by the elevator wire rope winding method, m = 1 when 1: 1 winding method, m = 2 when 2: 1 winding method;
Q—rated load capacity of the elevator;
∑W—Wj + Wg + Wp
In the type, Wi is the weight of the car; Wg is the weight of the wire rope between the car and the traction wheel when the car is at a low level; Wp is half of the tension load of the balance rope (when there is a balance compensation device).
Use and maintenance of manipulation wire rope
Inspection of wire rope
The condition of the elevator wire rope is directly related to the safety of the equipment and passengers. It must be paid sufficient attention. It should be carefully observed and carefully inspected during the work. The inspection content: (1) check the number, location and twist of broken wires Broken wire condition; (2) the diameter of the steel wire rope becomes thinner, in addition to visual inspection, periodically measure the rope diameter and wear with a vernier caliper; (3) check the tension of the elevator wire rope, the difference between the tension of each rope should not exceed 5%; Lubrication, cleanliness and corrosion of the steel wire rope; (5) The rope head and its combination, and whether there are other abnormal conditions such as the abnormal elongation of the rope.
Wear and deformation of wire rope
According to the experience of use, sudden breakage of the wire rope under normal working conditions is rare, and its damage is generally formed due to wear, bending fatigue, rust or trauma during long-term operation. Special attention should be paid to the inspection of wear and rust. Abrasion includes abrasion on the surface of the rope, between strands, and between wires.
Mechanical wear mainly includes three types: uniform external wear, deformation wear and internal wear, as shown in Figure 2 (click here). A is pure mechanical wear. Generally speaking, the elevator wire rope wears very slowly due to its higher hardness than the rope groove during use. However, due to tension, groove type, wire rope slipping, partial wear, and rolling in the groove, and abrasion with the rope groove occurs, this wear is uniform under normal circumstances. B is deformation and wear, which refers to the local wear and tear of the elevator rope in a certain section. Due to the chronic displacement of the elevator rope and the sheave or the severe vibration and impact of the elevator rope on the sheave, the elevator rope is locally deformed. Although the cross-sectional area of the elevator wire has not been reduced, the material of the wire at the local extrusion has been damaged and the wire is easily broken. C is internal wear. Due to the frequent bending of the elevator wire rope, the relative displacement between the steel wires in the strands, the contact pressure between the strands and the increase in the contact pressure between the strands, resulting in local indentations in the wires between adjacent strands. Over time, the stress concentration And broken. As mentioned above, the wear and thinning of the elevator wire rope will reduce the cross-sectional area of the elevator wire in the wire rope and reduce the tensile force. In severe cases, the elevator wire rope should be scrapped and replaced. According to experience, when the elevator wire rope has internal broken wires, the elevator wire rope can hear a "click" sound during operation.