How to select crane wire rope

Steel wire rope is widely used in construction cranes, which is generally made of many high-strength steel wires. It consists of a single steel wire wound together to form a strand, then some of the strands are wound into a rope core, and the outer strands composed of other strands are wound around the rope core to form a steel wire rope. Some imported steel wire ropes also contain a plastic ferrule, which is usually covered on the rope core in the form of plastic coating after special treatment. For important steel wire ropes, appropriate lubricant is filled in the rope to reduce friction. The domestic steel wire rope is generally divided into three types according to the rope core materials: organic matter (hemp core and cotton core), asbestos core or metal core. There is usually no filler or lubricant inside the rope. The steel wire rope can be divided into straight winding rope and cross winding rope according to the mutual direction of the steel wire winding into strands and strands winding into ropes, and can be divided into left and right co direction twisting and left and right mutual twisting according to the twisting direction of the strand rope; The imported steel wire rope is generally based on 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 relative to the longitudinal axis of the steel wire rope, which is divided into left rotation and right rotation. Accordingly, the direction of rotation of the strands is also specified, that is, the direction of the helix of the outer wire constituting the strands is the direction of rotation of each strand based on the longitudinal axis of the strands. When the ordinary steel wire rope is used, it will rotate 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 rotation of the hoisting steel wire rope, which is commonly known as twisting.

Compared with ordinary wire rope, non rotating wire rope has been widely used. The so-called non rotating steel wire rope is based on the principle that the torsion torque of the rope and the strand are opposite in direction and equal in size: the imported non rotating steel wire rope is different in that the rotation direction of the rope core is opposite to the rotation direction of the rope itself. When the rope is stressed, the torque generated by the rope core is equal to the torque generated by the outer strand and opposite in direction. The strands of the wire rope can also be compacted by post-treatment methods such as rolling or die extrusion. After treatment, the diameter of the strands will be reduced and the surface finish will be very high. Therefore, thicker steel wire can be used for the steel wire rope with tight strands. Under the same diameter, the filling coefficient of the steel wire rope with tight strands is higher and the breaking force is greatly improved. When multi-layer winding is carried out on the drum, the outer strand of the common wire rope is squeezed seriously between layers, and the surface of the wire rope is worn quickly. While 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 the unguided weight is lifted once or the unguided weight is lifted several times at a large height, the non rotating steel wire rope shall be selected;

2. Ordinary steel wire rope can be used when lifting a guided weight once or lifting a guided weight several times at a small height (such as traveling crane) or when left-hand and right-hand ropes are used in pairs.

The determination of the rotation direction of the wire rope shall follow: the drum with the right-hand rope groove is recommended to use the left-hand wire rope; on the contrary, the drum with the left-hand rope groove shall use the right-hand wire rope. For single-layer wound non rotating steel wire rope, the above principles must be strictly followed, otherwise the deformation of the steel wire rope structure may be easily caused; 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 force and the squeezing force of the steel wire ropes 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 pitch of the rope groove and the diameter of the rope groove should be selected to increase the contact area between the steel wire rope and the drum, reduce the friction force between the 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 the ropes tightly and effectively eliminate the phenomenon of rope climbing and rope disorder. Under the same diameter, the more the number of outer strands of the wire rope, the thinner the single wire. This kind of wire rope has good flexibility, which can overcome the reverse bending force of the wire rope when it enters and exits 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 force. Therefore, only when the two advantages are well combined, can the high-quality steel wire rope with high performance be achieved. In addition, the small diameter and small breaking force of steel wire rope shall meet the requirements of iso4308 standard during selection.