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Surface wear is the main reason for the breaking failure of the wire rope in service, particularly in the multi-layer winding hoist system of a coal mine. Understanding the effect of wear scars on the failure and mechanical properties of the rope is the effective way to ensure the safety of multi-layer winding hoist. In this paper, the breaking failure characteristics of hoist ropes with different wear scars were investigated by the breaking tensile test. The temperature rise in the wear scar regions was obtained and analyzed. Additionally, the finite element method was used to simulate the mechanical properties of the wear-out strands subjected to tensile load. Results show that the severe plastic deformation and obvious temperature rise occur in the wear scar region. The temperature rise curves during the breaking tensile test can reflect the number and the order of the fractured strands. The wear-out outer wires fracture earlier than the internal wires, and the wires with irregular wear scar always fracture along the sliding wear direction at the location with the maximum wear depth. Additionally, the wear scar caused by left cross contact will cause stress concentration and uneven distribution, and the wear depth makes it more obvious.

Friction and impact between steel wire rope always exist in multi-layer winding hoist during the winding-in process, in particular for an ultra-deep coal mine. To understand the friction and wear mechanisms of wire rope among the layers in the winding hoist, a series of sliding friction experiments were carried out using a self-made friction test rig. The results show that the coefficient of friction (COF) of the wire rope changes little with increasing load and stabilizes at approximately 0.73, but decreases with the sliding velocity under dry-friction condition. However, under lubrication condition, there is almost no effect of the contact load and sliding velocity on the COF, which stabilizes at approximately 0.35. Additionally, the temperature rise is concentrated at the contact area, and it increases with the load and the sliding velocity. The maximum temperature rise with the lubrication is much lower, approximately 10 °C, than that under the condition of dry-friction, which is approximately 103 °C. Furthermore, the maximum of the COF under the impact load is significantly lower than that for the stable contact friction. With the impact and sliding velocities increase, the maximum COF under the impact load experiences a slight increase and reaches a maximum value of approximately 0.36. As the impact load increases, the COF changes little, but the impact process occurs more than once.

Wear is one of the primary factors for the degradation of the wire rope used for multi-layer winding hoist. It decreases the carrying capacity and service life of the hoisting rope, which will affect the mine safety directly. In this paper, the effects of the wear scars caused by sliding friction under different crossing angles and cross directions on the mechanical response of the wire rope were investigated through the breaking tensile test. Additionally, the fracture failure mechanism of the rope samples was discussed. Results show that the surface wear decreases the breaking force of the wire rope. The distribution of wear region and the maximum wear depth of the wear scar are the major influence factors on the mechanical properties of the rope. The variation range of the breaking force is larger for the rope with the wear scar under the sliding condition of right cross contact and the damage is more serious for that in the condition of left cross contact. There is obvious plastic deformation and temperature rise near the wear scar before the rope breaks. The fracture failure mechanism is ductile fracture with necking and dimples on the surface.