How to select crane wire rope

Steel wire rope is widely used in engineering cranes. It is usually made of many high-strength steel wires. First, a single steel wire is wound together to form a strand, then some of the strands are wound into a rope core, and then the outer strands composed of other strands are wound around the rope core to form a steel wire rope. Some imported steel ropes also contain a plastic insert core, which is usually covered on the rope core through special treatment in the form of plastic coating. For important steel ropes, appropriate lubricant is filled inside the rope to reduce friction. Domestic steel wire ropes are generally divided into organic (hemp core and cotton core), asbestos core or metal core according to the core materials. There is usually no filler or lubricant inside the rope. According to the mutual direction of the steel wire wound into strand and the strand wound into rope, the steel wire rope can be divided into clockwise winding rope and cross winding rope, and can be divided into left and right same direction twisting and left and right alternating twisting according to the twist direction of the strand rope; Generally, the imported steel wire rope takes the cross wound rope as the standard rope. It is specified that the rotation direction of the steel wire rope is consistent with the rotation direction of the outer strand helix based on the longitudinal axis of the steel wire rope, which is divided into left rotation and right rotation. Accordingly, the rotation direction of the strands is also specified, that is, taking the longitudinal axis of the strands as the benchmark, the direction of the spiral line of the outer wire constituting the strands is the rotation direction of each share. When an ordinary steel wire rope is used in a single way, it rotates in the opposite direction to the steel wire rope. When it is used in the sliding group, the rotation of the steel wire rope will cause the twisting of the hoisting steel wire rope, which is commonly known as twisting.

Compared with ordinary steel wire rope, non rotating steel wire rope has been widely used at present. The so-called non rotating steel wire rope is based on the principle that the direction of the torsion moment of the rope and the strand is opposite and the magnitude is equal: the imported non rotating steel wire rope is different. The principle is to make the rotation direction of the rope core opposite to that of the rope itself. When stressed, the torque generated by the rope core is equal to that generated by the outer strand and the direction is opposite. The strand of steel wire rope can also be compacted by post-treatment methods such as rolling or die extrusion. After treatment, the diameter of the strand will be reduced and the surface finish will be very high. Therefore, the steel wire rope with tight strands can use thicker steel wire. Under the same diameter, the steel wire rope with tight strands has higher filling coefficient and greatly improved breaking force. When multi-layer winding is carried out on the drum, the outer strands of the common strand wire rope are severely squeezed between layers, and the surface of the wire rope is rapidly worn. The tight strand wire rope has high abrasion resistance and extrusion resistance.

Whether the steel wire rope is selected correctly or not will directly affect the service life of the rope and cause structural deformation, fracture and accidental failure of the rope. Therefore, the recommended selection principles are as follows:

1. when conducting one unguided weight lifting or multiple unguided weight lifting at a large height, the non rotating steel wire rope shall be selected;

2. ordinary steel wire rope can be used when carrying out one guided weight lifting or multiple guided weight lifting (such as crane) at a small height or when left-hand and right-hand ropes are used in pairs.

The rotation direction of the steel wire rope shall be determined according to the following rules: the drum with the right-hand rope groove is recommended to use the left-hand steel wire rope; on the contrary, the drum with the left-hand rope groove shall use the right-hand steel wire rope. For single-layer wound non rotating steel wire rope, the above principles must be strictly observed, otherwise it is easy to cause deformation of steel wire rope structure; For multi-layer winding, the rotation direction of the rope is determined by the direction of the rope groove of the drum, so as to lay a good foundation for the next layer. The mutual friction and extrusion force of the steel wire rope of the multi-layer winding drum are large, which is easy to cause rope disorder. Therefore, the steel wire rope with a diameter slightly smaller than the rope groove pitch and the rope groove diameter should be selected to increase the contact area between the steel wire rope and the drum, reduce the friction force between adjacent steel wire ropes, and improve the service life of the steel wire rope.

Practice has proved that the diameter of the steel wire rope is 1% smaller than the pitch of the rope groove, which helps to arrange ropes closely and effectively eliminate rope climbing and rope disorder. Under the same diameter, the more outer strands of the steel wire rope, the thinner the single steel wire. This kind of steel wire rope has good flexibility, can well overcome the reverse bending force when the steel wire rope enters and leaves the drum for many times, and it is easy to thread the rope. The thicker outer strand, the thicker the steel wire, can better resist wear, mechanical damage, corrosion and extrusion. Therefore, only when the two advantages are well combined, can the real high-performance high-quality steel wire rope be obtained. In addition, during the selection of steel wire rope, attention shall be paid to that its small diameter and small breaking force shall comply with the provisions of iso4308 standard.