Friction and wear behavior exists between hoisting ropes that are wound around the drums of a multi-layer winding hoist. It decreases the service life of ropes and threatens mine safety. In this research, a series of experiments were conducted using a self-made test rig to study the effects of the strand lay direction and crossing angle on the winding rope’s tribological behavior. Results show that the friction coefficient in the steady-state period shows a decreasing tendency with an increase of the crossing angle in both cross directions, but the variation range is different under different cross directions. Using thermal imaging, the high temperature regions always distribute along the strand lay direction in the gap between adjacent strands, as the cross direction is the same with the strand lay direction (right cross contact). Additionally, the temperature rise in the steady-state increases with the increase of the crossing angle in both cross directions. The differences of the wear scar morphology are obvious under different cross directions, especially for the large crossing angle tests. In the case of right cross, the variation range of wear mass loss is larger than that in left cross. The damage that forms on the wear surface is mainly ploughing, pits, plastic deformation, and fatigue fracture. The major wear mechanisms are adhesive wear, and abrasive and fatigue wear.
The scoop cooling system is widely used in advanced ships which usually requires a water inlet device protruding out of the board. The structure of the water inlet device not only determines the cooling water flow into the system, but also affects the additional resistance of the hull. The ratio of the static pressure difference between windward side of the device and the environment and the dynamic pressure head of the cooling water entering the flow channel is defined as the scoop lift head. The scoop lift head and additional resistance are used to describe the hydraulic performance of the water inlet device of the scoop cooling system, and a theoretical analysis method for the performance of the water inlet device of the scoop cooling system is proposed. The actual ship parameters are used to verify the scoop cooling capability and drag resistance characteristics of the water inlet device.
This article is based on a certain type of hoist drum, Moreover, we make the stress and mode analysis for the drum, and make preliminary check on it. Then find the position of the weak section, we calculate the force in each stage of hoisting system and draw force-timing load spectrum,we translate it into stress function of weak link. Based on above studies and conclusion, in line with the materials of the drum and Fatigue characteristic parameters and appropriate fatigue lifetime prediction model, we analysis the fatigue performance, in the end get the distribution of the drum’s fatigue life and the life of plane of weakness.
In the mining of ultra-deep resources, workers need to use ultra-deep mine lifting equipment to lift minerals, in order to ensure the synchronization between ropes during the lifting process. The article analyzes the change in the length difference between the steel ropes from the perspective of rope groove deformation. This work considers the influence of the weight of the vertical rope, analyzes the variation of surface load on the rope groove, establishes the expressions for deformation at the rope groove, and analyzes the influence of rope groove deformation on the difference in the length of the wire ropes. The results show that in the ultra-deep mine multi-layer winding lifting system, the rope groove load varies with the height of the rope. The rope groove deformation curve is similar to the quadratic function curve, and the maximum point is close to the middle position. Based on these results, the article studies the influence of the imbalance between the circles, the winding gap, and the rope-out method on the difference in the length of the wire ropes. It is found that, the extent of the lack of synchronization between the rings has a greater influence on the change in the length of the wire rope, and a wire rope wound under the reel is more conducive to ultra-deep mine lifting.
In the practical engineering, to solve the small failure probabilities with correlated high-dimensional variables, the subset simulation (SS) is combined together with the Monte Carlo and importance sampling (IS) method. The samples from the probability density functions (PDF) of the importance sampling are used to construct the intermediate failure events, by which the small failure probabilities are turned into a Markov chain (MC), which is a continuous product made of a series large failure probability or conditional failure probability (CFP) which is easily answered, on which the structural reliability can be efficiently simulated by directly obtaining the samples with correlated ones. Finally, the 3 planet carriers of 3 grade planetary reducers in shield tunneling machine(STM) are as examples to check the algorithm above, the results show that the SS of the IS with correlated variables can highly simulate failure probability.
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