Key points for selection of crane wire rope

According to the core material of the rope, the steel wire rope is generally divided into organic matter (hemp core and cotton core), asbestos core or metal core. There is usually no filler or lubricant inside the rope. According to the mutual direction of steel wire winding into strand and strand winding into rope, steel wire rope can be divided into clockwise winding rope and alternating winding rope, and can be divided into left and right same direction twisting and left and right alternating twisting according to the twisting direction of its strand rope; Generally, the imported steel wire rope takes the cross wound rope as the standard rope, and 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 rotation direction of the strand is also specified, that is, taking the longitudinal axis of the strand as the benchmark, the direction of the spiral line of the outer wire constituting the strand is the rotation direction of each share. When a single ordinary steel wire rope is used, it rotates in the opposite direction to the steel wire rope. When it is used in the pulley block, the rotation of the lifting steel wire rope will be caused by the rotation of the steel wire rope, which is commonly known as twisting. Compared with ordinary steel wire ropes, non rotating steel wire ropes have been widely used at present, such as 18*7 and 35w*7. The so-called non rotating steel wire rope is based on the principle that the direction of the torsional torque of the rope and the strand is opposite and the size 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 the rotation direction of the rope itself. When stressed, the torque generated by the rope core is equal to the torque 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 wires. Under the same diameter, the steel wire rope with tight strands has a higher filling coefficient and a greatly improved breaking force. When multi-layer winding is carried out on the drum, the outer strands of the common wire rope are squeezed seriously between layers, and the surface of the wire rope is worn faster. The tight strand wire rope has high wear resistance and extrusion resistance.

Whether the steel wire rope is selected correctly or not directly affects the service life of the rope and causes structural deformation, fracture and accidental failure of the rope. Therefore, the recommended selection principles are as follows: when the unguided weight is lifted once or the unguided weight is lifted many times at a large height, the non rotating steel wire rope is selected; Ordinary steel wire rope can be selected when carrying out a guided weight lifting or multiple guided weight lifting at a small height (such as crane) or when left-hand and right-hand ropes are used in pairs.

The determination of the rotation direction of the steel wire rope should follow: the drum of the right-hand rope groove is recommended to use the left-hand steel wire rope; On the contrary, the drum with left-hand rope groove should use right-hand wire rope. For single-layer wound non rotating steel wire rope, the above principles must be strictly observed, otherwise it is easy to cause permanent deformation of the steel wire rope structure; For multi-layer winding, the rotation direction of the rope is determined by the direction of the drum rope groove, so as to lay a good foundation for the next layer. The friction and extrusion force between 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 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 steel wire rope is 1% smaller than the pitch of rope groove, which helps to arrange ropes closely and effectively eliminate rope climbing and rope disorder. Under the same diameter, the more the outer strands of the steel wire rope, the thinner the single steel wire. This kind of steel wire rope has good flexibility, which 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, whose steel wire is also thicker, can better resist wear, mechanical damage, corrosion and extrusion. Therefore, only a good combination of the two advantages is a really high-performance high-quality steel wire rope. In addition, the minimum diameter and minimum breaking force of steel wire rope shall comply with the provisions of iso4308 standard.