Structure composition and category of the most pop

2022-09-21
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Structural composition and category of hoisting wire rope

wire rope has high strength, light weight, good flexibility, impact resistance, safety and reliability. Under normal circumstances, the steel wire rope used will not break suddenly, but it may be damaged because the load it bears exceeds its ultimate breaking force. The damage of steel wire rope is premonitory. It always starts from the broken wire, and the sudden fracture of the whole rope rarely occurs. Steel wire rope is widely used in cranes. The damage of steel wire rope will lead to serious consequences, so steel wire rope is not only one of the important parts of lifting machinery, but also the key link to ensure the safety of lifting operation

1. structure of steel wire rope

steel wire rope is a spiral rope twisted by a certain number of strands with the rope core as the center

(1) steel wire. Steel wire rope plays the role of bearing load, and its performance is mainly determined by steel wire. Steel wire is a round (or shaped) wire made of carbon steel or alloy steel by cold drawing or cold rolling, which has high strength and toughness. The surface of steel wire is treated according to different environmental conditions

(2) rope core. It is used to increase the elasticity and toughness of steel wire rope, lubricate copper wire, reduce friction and improve service life. Commonly used rope core organic fiber (such as hemp, cotton), synthetic fiber, asbestos core (high temperature conditions) or soft metal and other materials

2. type of steel wire rope

the steel wire rope for crane adopts double stranded round steel wire rope

(1) according to the contact state of steel wire, it can be divided into point contact, line contact and surface contact steel wire rope (see Figure)

① point contact steel wire rope (also known as ordinary type, see figure a) is twisted with equal diameter steel wire. Because the lay distance of each layer of steel wire is different, a point contact is formed between each layer of steel wire and steel wire (see figure a). When loaded, the contact stress of the steel wire is very high, easy to wear and break, and the service life is low. The advantage is that the manufacturing process is simple and cheap. The point contact steel wire rope is often used as a lifting device, so natus only needs to use the existing mold and make a small repair in production. A more environmentally friendly and efficient processing technology has become the focus of processing enterprises. The binding sling for heavy operation has also been adopted, and the working mechanism of the crane has also been adopted

② wire contact wire rope is made of steel wires with different diameters. The inner and outer steel wires are properly configured to form line contact between different layers of steel wires (see figure 6-8b), so as to reduce the contact stress of steel wires under load. The wire contact rope has high bearing capacity, good flexibility and high service life. The commonly used wire contact wire ropes are sear type (also known as outer thick type, see Figure b), Warrington type (also known as thick thin type, see Figure C) Filling type (also known as dense type, see figure 6-9d), etc. (the crane design code recommends that wire contact wire rope be preferentially used in the working mechanism of the crane.

③ face contact wire rope (also known as sealed type, see figure 6-9e). Usually, round steel wire is used as the strand core, and the outermost layer or layers are made of steel wire with special-shaped cross-section. The layers are in surface contact (see Figure C), which is wound by extrusion. It is characterized by smooth surface, good flexibility and high strength. Corrosion resistant, but the manufacturing process is complex and the price is high. It is rarely used on cranes. It is often used as the bearing rope of cable cranes and aerial ropeways

(2) classify according to the lay direction of steel wire rope. According to whether the direction of the wire rope twisted into strands is consistent with the direction of the wire rope twisted into strands, it can be divided into:

① interactive twisted wire rope (also known as cross wound rope). The direction of twisting the silk into strands is opposite to that of twisting the strands into ropes. Since the grabbing direction of the strand and the rope is opposite (see figure 6-10c, D, which needs the tilt support of the national policy), it is not easy to twist and loosen in use, and it is widely used on cranes

② lay steel wire rope in the same direction (also known as along winding rope). The direction of twisting the wire into strands is the same as that of twisting the rope into strands (see Fig. 6-10a, b), and the flexibility and service life are better than those of interactive twisting rope. However, because it is easy to twist and loose, it is generally only used as traction rope

③ do not twist the steel wire rope. This kind of steel wire rope is designed so that the torsion moment of the strand and the rope is equal and the direction is opposite, which overcomes the torsion phenomenon in use. It is often used on cranes with large lifting height, and is paid more and more attention. It is expected to achieve an annual capacity of 520000 tons of high-performance new materials

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