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Wire Rope Basics and Acceptance Criteria

First, the definition of wire rope

The steel wire rope is a helical wire bundle in which the steel wires whose mechanical properties and geometric dimensions meet the requirements are twisted together according to certain rules. The steel wire rope is composed of steel wire, rope core and grease. The steel wire rope is first twisted into strands by multiple layers of steel wires, and then twisted into a helical rope by a certain number of strands with the rope core as the center. In material handling machinery, wire ropes are used for hoisting, pulling, tensioning and carrying. The steel wire rope has high strength, light weight, stable operation, not easy to break suddenly and reliable operation.

steel wire rope Second, the composition and function of wire rope

The steel wire rope is mainly composed of steel wire, rope core and grease.

1. Steel wire

The steel wire rope needs to be subjected to alternating loads during its use, and its performance is mainly determined by the mechanical properties of the steel wire, the surface state of the steel wire and the structure of the steel wire rope. The steel wire material includes carbon steel or alloy steel, which is made by cold drawing or cold rolling. The cross section of the steel wire is round or special-shaped (T-type, S-type, Z-type). The special-shaped cross-section steel wire is mainly used for the production of sealing wire ropes. High tensile strength and toughness, and suitable surface treatment of steel wire to meet the needs of different environmental conditions./

2. Rope core

The main function of the rope core is to support the wire rope to achieve a stable cross-sectional structure. The rope core includes steel core and fiber core, fiber core includes natural fiber core and synthetic fiber core, natural fiber core such as sisal, jute, cotton thread, etc., synthetic fiber core includes polyethylene and polypropylene filament, etc. The natural fiber core can store more grease, which can lubricate the wire rope and prolong the service life of the wire rope./

3. Grease

There are two main functions of spraying grease during the twisting process of the steel wire rope. One is to lubricate the steel wire rope to reduce the wear on the surface of the steel wire. act as an inhibitor.

Wire rope structure diagram
Three, the classification of wire rope

Wire ropes can be classified according to the material of the rope making wire, the surface state, the twisting method and the use of the wire rope.

1. According to material classification

①Carbon steel wire rope is twisted with high-quality carbon structural steel wire as raw material.

②Stainless steel wire rope is made of stainless steel wire as raw material and twisted.

2. Classification according to surface state

①Phosphating coated steel wire rope, referred to as phosphating steel wire rope, the weight of the phosphating film on the rope making steel wire is 3-60 g/square meter. , The phosphating film can improve the wear resistance and corrosion resistance of the surface of the rope making wire, and effectively inhibit the occurrence of fretting fatigue.

②Galvanized steel wire rope, including hot-dip galvanizing and electro-galvanizing. The protection of the galvanized layer on the steel wire belongs to anodic protection. The thicker the galvanized layer, the stronger the anti-corrosion ability.

③ Plastic-coated steel wire rope, coat the outer surface of the steel wire rope or the outer surface of the strand rope with a certain thickness of plastic, including polyethylene, polypropylene, polyurethane, etc.

④Smooth steel wire rope, the rope-making wire obtained by cold drawing of raw materials after heat treatment and surface preparation, the steel wire is directly twisted into strand rope, steel core and steel wire rope without any surface treatment.

3. Classification according to twisting method/

①Single-strand rope is also called single-strand rope.

②Double-twisted rope is made by twisting double-strand rope around the rope core (steel core or fiber core), which can be twisted with one or more layers of steel wire.

③Three-twist rope is made by twisting double-twist rope around the rope core, mainly used for thick-gauge steel ropes with a diameter of more than 60mm, such as offshore steel wire ropes.

4. Classify according to status

① Steel wire rope with point contact: The diameter of the steel wires in the strands is the same, the lay angle between the steel wires in each layer is the same, and the lay length is different, so the inner and outer layers of steel wires cross each other and are in a point contact state.

②Wire rope in line contact: the lay length of each layer of steel wire in the strand is the same and the lay angle is different. Under the same conditions of use, the service life of line contact wire rope is longer than that of point contact wire rope.

③Compacted steel wire rope, formerly known as surface contact wire rope, during the twisting process of the steel wire rope, through forging, drawing, etc., the contact surface is formed between the steel wires, including strand rope compaction, wire rope compaction and double strand compaction, etc. .

④Sealing steel wire rope: The outer layer is made of special-shaped steel wire, including steel wire with T-shaped S-shaped Z-shaped section structure, with smooth surface and good wear resistance. Compared with other types of steel wire ropes of the same diameter, the tensile strength is higher, and It bears lateral pressure, but has poor flexibility, complex process and high manufacturing cost. It is often used as a bearing cable, such as cable cranes and cables on aerial ropeways.

Fourth, the application and inspection of wire rope/

Due to the unique properties of steel wire ropes, a more ideal product has not been found at home and abroad to replace steel wire ropes comprehensively or in one field. Therefore, steel wire ropes are used in metallurgy, mining, oil and gas drilling, machinery, chemical industry, aerospace and other fields. It has become an indispensable component or material, and its quality has also been concerned by many domestic industries, and a lot of manpower and material resources have been invested in the research and product development of wire rope use.

Application of wire rope
Before being put into production and use, the wire rope product must be checked for acceptance. The significance of this step is to accurately and truly reflect the quality status of the wire rope, so as to predict the life of the wire rope, avoid potential safety hazards, and ensure safe production. The following is a brief introduction to the acceptance criteria for wire ropes:

1. Inspection items

Wire rope acceptance inspection items mainly include the following six items: ① shape and size ② structure inspection ③ surface quality ④ supplier inspection report ⑤ strength test ⑥ fatigue test.

2. Inspection equipment

Micrometer, Wancha ETM504C microcomputer-controlled electronic universal testing machine, Wancha steel wire rope bending fatigue testing machine.

3. Acceptance criteria

①Dimensions and structural requirements

The diameter of the steel wire rope can be measured with a micrometer, and the structure can be observed with the naked eye. However, due to the different application industries and uses of the steel wire rope, the requirements for the size and structure are also different, so the specific inspection is based on the actual situation.

②Surface quality of wire rope

The surface quality of the wire rope can be observed with the naked eye. The specific requirements are as follows:

1. The steel wire rope is made of galvanized steel wire, and the galvanized layer of the steel wire should be uniform, continuous, without cracks and peeling;

2. Each strand of the steel wire rope and each steel wire in each strand shall be tightly twisted, and there shall be no stack marks, protrusions, breaks, crush injuries and disorderly intersecting wires;

3. The surface of the steel wire in the wire rope should not have defects such as scratches, flattening or hard bending.

③ Each batch of products requires the supplier to provide an inspection report, and carefully check whether the relevant performance of the product is qualified.

④The breaking force and tensile strength of the wire rope.

The breaking tensile force and tensile strength of steel wire rope can be measured by Wanshi ETM504C computer-controlled electronic universal testing machine. For specific test methods and parameters, please refer to GB/T 8358-2006 “Wire Rope Breaking Tensile Test Method”, which specifies the breaking force of steel wire rope. Tensile test method terms and definitions, test principles, sample preparation, test procedures and test reports.

⑤Bending fatigue test

In some occasions, fatigue is the main reason for the damage of the wire rope. Using the Wanchen wire rope bending fatigue testing machine to test the performance of the wire rope to withstand bending fatigue. In YB/T 4288-2012 “Elevator Wire Rope Bending Fatigue Test Method”, the terms and definitions, test principle, test device, test parameters, sample requirements, test procedure and test report of elevator wire rope bending fatigue test are specified.

4. Inspection record

The inspection results are recorded on the incoming inspection record. Those that are judged to be qualified are directly put into storage, and those that are judged to be unqualified will be notified to the supplier for return processing.