1. The mechanism of wear between the wire rope and the friction pulley liner

1.1 Adhesive wear

When the wire rope is in contact with the friction pulley liner, the strands of the wire rope are pressed into the groove of the friction pulley liner,and the normal force generated by the load is borne by the uneven top end. At these contact points, the local stress is very large, so that the two surfaces lean against each other. Very close, due to the existence of van der Waals, the atoms on the two surfaces attract each other to produce bonding points, which is so-called "cold welding", and these bonding points must be destroyed if the steel wire rope moves relative to the friction pulley line. Since the strength and hardness of the wire rope are much greater than that of the friction pulley liner, the wear is only on one side of the friction pulley liner. When there is a layer of oil film on the wire rope, the two friction surfaces are separated by the oil film, most of the peaks on the friction surface do not directly contact, only a small part of the peaks rupture the surface oil film under greater pressure and contact together Therefore, the molecular attraction between friction surfaces is much smaller than when there is no oil film, the formation of bonding points is difficult, and the number of them is also small. On the contrary, if the surface of the steel wire rope is not coated with oil, and the two friction surfaces are directly attached to each other, the attraction between the molecules is large, the formation of bonding points is easier and the number is large.

In addition, during the friction process, the surface temperature of thefriction pulley lineris also very high. This is mainly due to the fact that most of the dissipated friction energy is converted into heat, and the material used in the friction pulley linerhas a small thermal conductivity, and most of the heat is concentrated on the surface of thefriction pulley liner.The surface temperature rises, causing the softening and melting of the friction pulley linersurface. The softened material and the melting peak will transfer to the surface of the wire rope during the friction process, forming thermal adhesive wear. When there is an oil film on the surface of the steel wire rope, since Goppey oil cannot infiltrate the friction pulley linermaterial, it is difficult for the softened and melted liner material to adhere to the steel wire rope, so the transfer film is not easy to form, and the thermal adhesion effect is weak. On the contrary, if the surface of the wire rope is not coated with oil, the thermal adhesive wear is more serious.

1.2, fatigue wear

Fatigue wear refers to when two contact bodies are relatively rolling or sliding, if the cyclic stress formed in the contact area exceeds the fatigue strength of the material, cracks will be initiated on the surface and gradually propagate, and finally the material above the crack will be broken and peeled off. process. Because the movement of the wire rope relative to the liner is reciprocating, there are sliding along the length of the rope and sliding along the circumferential direction. The micro-protrusions on the surface of the liner collide with the micro-protrusions on the surface of the wire rope. Alternating fatigue stresses are generated in the subsurface layer, causing fatigue cracks in the weak links of the subsurface layer, and gradually expand, and finally fracture to form fatigue wear.

1.3 Abrasive wear

Abrasive wear refers to the phenomenon of material loss caused by the interaction of material particles or hard microprojections with the surface of the material. During the friction process, the protrusions on the wire rope are pressed into the pad to a certain depth under the action of positive pressure, and slide along the pad to cause abrasive wear. This wear includes two aspects, micro-cutting and furrowing effect. The force exerted by the micro-protrusion on the gasket can be divided into tangential force and normal force. When the angle is appropriate, that is, when the angle of attack is greater than the critical angle, the micro-protrusion cuts the surface of the gasket like a tool and produces cutting. That is, a microscopic cutting effect is produced; another part of the micro-protrusions just push the material to the front and sides. The material is not cut but only produces plastic deformation. After repeated plastic deformation, brittle fracture is caused, which is the furrow effect. Studies have shown that the amount of wear caused by furrows accounts for a small proportion of the total amount of wear.

1.4 Corrosion and wear

Corrosion wear refers to the phenomenon that when the friction pair is gathered in the friction process, the friction surface and the surrounding medium undergo chemical or electrochemical reactions, resulting in material loss. Because the wire rope runs in the shaft, some mine shafts are heavily sprayed and the water has a high pH, ??which can easily cause corrosion to the surface of the wire rope and liner. For example, the surface of the wire rope reacts quickly with the oxidizing medium, and the formed oxide film rubs against the liner. After the time is worn off from the surface, a new oxide film will soon form, and the acid, alkali, salt and other chemical media in the water will also chemically corrode the surface of the wire rope and gasket, causing corrosion and wear.

1.5, fretting wear

Fretting wear refers to a form of wear caused by a small amplitude sliding between friction surfaces. In the operation of multi-rope friction hoisting, it is usually considered that the wire rope and the pad are relatively static, but in fact, because the tension of the wire rope is variable and in a state of vibration, the wire rope is elastic, so the wire rope will become longer after being pulled. After the friction wheel rotates, relative sliding and peristalsis will occur between the wire rope and the liner, that is, "elastic sliding". The sliding direction slides from the side with the smaller pulling force to the side with the larger pulling force. In this tiny "elastic sliding" process will produce fretting wear.

2. Factors affecting the wear between the wire rope and the gasket

2.1, the influence of material properties

The steel wire rope material used for multi-rope friction lifting is generally high-quality carbon structural steel, and the gasket material is generally PTFE or polyurethane. In terms of hardness, the hardness of the wire rope is greater than the hardness of the liner, so adhesive wear will occur; from the point of view of material, the smelting and processing quality of the wire rope and its microstructure will affect the fatigue resistance of the wire rope, such as the material of the wire rope It contains non-metallic inclusions, especially brittle oxides with edges and corners and other complex point and spherical inclusions, which are prone to fatigue and wear under the action of alternating stress. Similarly, if the material of the gasket is poor, the wear resistance is low and the life is short.

2.2 The impact of stress

Obviously, if the pressure between the wire rope and the liner is high, the wear will be greater. On the contrary, if the pressure is small, the wear will be small. Without pressure, the wear will be zero. For multi-rope wire hoisting, on the one hand, in order to improve the lifting capacity and prevent the wire rope from slipping on the friction wheel, it is necessary to increase the pressure between the wire rope and the liner; on the other hand, in order to reduce the wear between the wire rope and the liner, Need to reduce the pressure. Therefore, comprehensive consideration is required.

2.3 The influence of surface roughness

The surface of the wire rope and the liner has a certain degree of roughness, that is, micro-protrusion, which is necessary to ensure that there is a certain coefficient of friction between the wire rope and the liner and the surface of the wire rope is coated with Goppey oil, but excessive roughness will cause The abrasion between the two surfaces increases. If broken wires and burrs appear on the surface of the wire rope, the liner will be severely worn.

2.4. Environmental impact

Water spraying in the mine shaft will not only reduce the friction coefficient between the wire rope and the liner, but also have a direct impact on the wear and corrosion of the wire rope, reducing the service life of the wire rope and the liner. Because of the movement of the lifting container and the air flow, the mine water will mix coal dust particles on the hoisting wire rope, which will increase the mutual wear between the hoisting wire rope and the liner. The mine water will cause the wire rope to rust. When it is acidic, the corrosion of the wire rope will be more serious, and it can be seen that the mine environment will affect the corrosion and wear between the wire rope and the liner.

2.5. The influence of sliding speed

The multi-rope friction hoisting wire rope and the liner are relatively static at a certain moment, but the surfaces in contact with each other are constantly changing. The hoisting wire rope is elastic and bears the tensile force and produces "elastic sliding", which affects the microscopic distance between the wire rope and the liner. Dynamic wear. If the wire rope slides on the friction wheel for a certain period of time, it will cause severe adhesive wear and abrasive wear between the wire rope and the liner, and as the sliding speed increases, the amount of wear also increases.

Measures to reduce the wear between the wire rope and the gasket

1) Multi-rope friction lifting selects triangular strand steel wire rope and GDM326 liner, selects excellent material and processing technology, the surface of the steel wire rope is coated with Goppey oil and the outer steel wire should be thick. The liner has certain elasticity and does not affect the connection with the steel wire Coefficient of friction

2) Adjust the tension balance of the wire rope in time to avoid excessive stress on a certain wire rope, which may cause increased wear.

3) Under the condition that the lifting task is completed and the wire rope does not slip, the lifting capacity and the container weight or counterweight should be reduced as much as possible to reduce the positive pressure on the friction surface between the wire rope and the liner.

4) Clean the surface of steel wire rope and gasket in time, remove coal dust and impurities, and reduce corrosion and wear.