1. Influence of wire rope pressing and lubrication
Wire rope pressing is a spiral wire rope that winds steel wires with good mechanical properties according to certain rules. Its main components include rope-making wire, grease and rope core (fiber core or steel core). Steel wire ropes include high-quality carbon steel wires and stainless steel wires, as well as galvanized steel wires and galvanized aluminum alloy steel wires made of coated high-quality carbon steel wires. Most wire rope pressings are greased, and the fiber core of the wire rope pressing is impregnated with core grease. Due to limitations of usage conditions, there are several types of wire ropes that are not greased. Decades ago, many wire rope press manufacturers and users have noticed that lubrication conditions have a crucial impact on the service life of wire rope presses.
At present, each wire rope pressing manufacturer will lubricate the wire rope in the early stage of wire rope production. The grease coating in the wire rope pressing and manufacturing process generally uses wire rope coating and strand coating in sequence. It is now considered that a reasonable method of grease application is to spray oil mist before the closing point of the steel wire during twisting. That is, by improving the grease application method, the grease can be evenly distributed on the surface of the rope-making steel wire to a greater extent, so as to ensure that any grease in the steel wire rope is suppressed. The lubrication effect between two steel wires in contact with each other.
2. Wear of wire rope during use
In addition to lubrication of wire ropes during the production process, wire rope pressing can also be lubricated and maintained during daily use. Through the study of failed wire ropes in port bridge cranes, the fractures were detected and metallographically analyzed. The nature of wire rope breakage is fatigue fracture. The source of fracture is located at the damage or wear on the surface of the wire. There are defects such as wear, extrusion, and peeling on the broken surface. The broken parts of some steel wires are severely worn, and the broken cross-sectional area is only 60% of the original steel wire. Through the inspection and analysis of the internal wire fractures of the scrapped steel wire ropes, it was confirmed that most of the broken steel wire surfaces had obvious wear. The fracture nature of the steel wire fractures was fatigue fracture, that is, during the actual use of the steel wire ropes, the surface of the steel wires first showed obvious wear, and then under alternating stress. Fatigue fracture occurs under the action, eventually leading to the failure of the steel wire rope.
3. The impact of lubrication on the service life of wire ropes
The wear of the steel wire rope includes the wear of the outer surface of the steel wire rope and the wear of the inner surface of the steel wire rope. The wear of the outer surface of the wire rope is caused by the contact friction between the wire rope and the reversing sheave groove and the relative sliding of the contact object. Wear on the outer surface of the wire rope occurs on the visible portion of the outer strands of the wire rope. The wear of the steel wire rope includes the wear of the outer surface of the steel wire rope and the wear of the inner surface of the steel wire rope. The wear on the outer surface of the wire rope is caused by the contact friction between the wire rope and the reversing sheave groove and the relative sliding of the contact object. Wear on the outer surface of the wire rope occurs on the visible portion of the outer strands of the wire rope. Relative sliding occurs between them. The wear on the surface of the inner wires of the failed wire rope proves the existence of this relative sliding between the wires, because relative sliding is a prerequisite for wear.
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