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Key points for selection of crane wire rope
2021-12-16
Domestic steel wire ropes are generally divided into organic matter (hemp core and cotton core), asbestos core or metal core according to the rope core material. There is usually no filler or lubricant inside the rope. According to the mutual direction of the steel wire wound into strands and the strands into the rope, the steel wire rope can be divided into the winding rope and the cross winding rope, and according to the twist direction of the strand rope, it is divided into left and right twists in the same direction and left and right alternating twists; imported steel wire ropes Generally, the winding rope is used as the standard rope, and the direction of the wire rope is specified to be consistent with the direction of the outer strand helix relative to the longitudinal axis of the wire rope, which is divided into left-handed and right-handed. Correspondingly, the twist direction of the strands is also specified, that is, the direction of the helix of the outer filaments constituting the strands is the twist direction of each share based on the longitudinal axis of the strands. Ordinary steel wire ropes have the phenomenon of rotating in the opposite direction when the steel wire rope is used in a single rope. When used in a pulley block, the steel wire rope will be twisted due to 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 begun to be widely used, such as 18*7, 35w*7. The so-called non-rotating steel wire rope is based on the principle that the twisting moment of the rope and the strands is opposite and equal in magnitude: 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 force is applied, the torque generated by the rope core is equal to the torque generated by the outer strands, but the direction is opposite. The strands of the steel wire rope can also be made into compact strands 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 high. Therefore, the densely stranded wire rope can use thicker steel wires. Under the same diameter, the densely stranded wire rope has a higher filling factor and greatly improves the breaking force. When multi-layer winding is performed on the reel, the outer strands of ordinary strands of steel wire ropes are squeezed more severely between layers, and the surface of the wire rope wears faster. The tightly stranded steel wire rope has higher abrasion resistance and anti-extrusion ability.
Whether the wire rope is selected correctly or not will directly affect the service life of the rope and cause structural deformation, breakage and accidental failure of the rope. Therefore, the recommended selection principles are as follows: When lifting an unguided heavy object or performing multiple unguided heavy lifting at a larger height, use a non-rotating wire rope; when performing a guided heavy lifting or at a smaller height Ordinary steel wire ropes can be used when multiple guided heavy lifting (such as driving) or left-handed and right-handed ropes are used in pairs. The determination of the direction of the wire rope should follow: the drum with the right-handed rope groove is recommended to use the left-handed wire rope; conversely, the drum with the left-handed rope groove should use the right-handed wire rope. For single-layer winding non-rotating steel wire ropes, the above-mentioned principles must be strictly observed, otherwise it will easily cause permanent deformation of the steel wire rope structure; in the case of multi-layer winding, the rotation direction of the rope is determined by the direction of the rope groove of the drum, so as to be used for the next layer. Good foundation. The friction force between the steel wire ropes of the multi-layer winding drum and the squeezing force are relatively large, which is easy to cause the phenomenon of rope disorder. Therefore, a steel wire rope with a diameter slightly smaller than the rope groove pitch and the rope groove diameter should be selected to increase the wire rope and the drum. The contact area between the adjacent steel wire ropes reduces the friction between the adjacent steel wire ropes, thereby increasing the service life of the steel wire ropes. Practice has proved that the diameter of the wire rope is 1% smaller than the pitch of the rope groove, which helps to arrange the rope tightly and effectively eliminates the phenomenon of rope climbing and messy rope. Under the same diameter, the more the number of outer strands of the wire rope, the thinner the single steel wire. This kind of wire rope has good flexibility and can well overcome the reverse bending force of the wire rope when it enters and exits the reel multiple times. easy. The thicker outer strands have thicker steel wires, which can better resist abrasion, mechanical damage, corrosion and squeezing force. Therefore, only a good combination of the two advantages can be a truly high-performance, high-quality steel wire rope. In addition, the minimum diameter and minimum breaking force of the wire rope should meet the requirements of the ISO4308 standard during the selection process. |
