Wire rope casting manufacturers consider that when lifting a load, if the wire rope does not rotate around the longitudinal axis or barely rotates around the longitudinal axis, the wire rope is a non-rotating wire rope. This characteristic is caused by the opposite twisting directions of the inner and outer strands. When a load is applied to a non-rotating wire rope, the torque produced by the core of the rope is opposite to the torque produced by the outer strands, creating a balance. Its characteristics are:
1. The wire rope rarely rotates or does not rotate at all when it is loaded.
2. Steel wire rope has high fatigue resistance.
3. The wire rope has high flexibility and is easy to operate.
4. Rotational stability.
Wire rope casting manufacturers believe that in a single rope lifting system, when the weight of the wire rope is ignored, the rotation of the wire rope is proportional to the length of the hanging wire rope.
When a wire rope is subjected to a tensile load, it stretches in different stages. Pretensioning the wire rope before use is the main means to eliminate its structural elongation.
Steel wire rope casting manufacturers believe that there are many factors that cause the wire rope to elongate during use, and some factors cause the elongation to be negligible. Usually the main reasons for the elongation of the wire rope are as follows, of which the first two are important factors.
1. Structural elongation: the elongation caused by the adjustment of the position of each steel wire and the wire rope; the elongation caused by the increase in the twist length caused by the free rotation of one end of the wire rope; the collective name for further elongation caused by the reduction in the metal area of the wire rope due to internal wire wear For structural elongation.
2. Elastic elongation: The elongation caused by the secondary load of tension within the elastic range of the material.
3. Plastic elongation: Permanent and inelastic elongation caused by loads that exceed the yield point of the material.
4. Temperature: Elongation or shortening caused by temperature changes.
The function of wire rope pretension:
1. Wire rope casting manufacturers believe that when the wire rope is pre-tensioned, the elongation caused by adjusting the position of each wire and the wire rope can basically be eliminated. The method is to repeatedly stretch under a certain load until the structural elongation of the steel wire rope is eliminated.
2. Eliminate torsional stress: After torsion, the steel wire rope strands and the steel wires in the strands will have some residual stress. By pretensioning, torsional stresses can be largely eliminated.
3. Make the force on the steel strands and steel wires uniform: Due to the uneven twisting, the force on each strand or wire of the steel wire rope is uneven when it is stressed. It can be made uniform by pre-tensioning.
4. Improve fatigue life: Steel wire rope casting manufacturers believe that the fatigue life of steel wire ropes can be improved to a certain extent due to the elimination of torsional stress and uniform stress.
Steel wire rope casting manufacturers believe that the wear resistance and fatigue resistance of steel wire ropes are characteristics that influence each other, and the main influencing factor is the outer steel wire of the steel wire rope. For steel wire ropes with the same diameter, same strength, and same number of strands, the greater the number of strands of the outer steel wire and the smaller the diameter of the outer steel wire, which means that the steel wire rope has poor wear resistance and better fatigue resistance. Vice versa, when selecting a steel wire rope, the wear resistance and fatigue resistance of the steel wire rope should be comprehensively considered to meet the application requirements of the steel wire rope as much as possible.
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