Study on the Non-Steady-State Wear Characteristics and Test of the Flow Passage Components of Deep-Sea Mining Pumps

In the process of conveying coarse-grained minerals, the internal flow-through passage components of mining pumps are subject to wear. The flow of coarse particles in such pumps is complex and changes constantly, making it necessary to study the non-steady-state wear characteristics and test the flow passage components. The evolution of the surface wear rate for the flow passage components during one third of a rotation cycle (120°) of a mining pump impeller with small, design, and large flow rates was analyzed in this study based on a discrete phase model (DPM). The flow that occurs during an entire rotation cycle of the impeller was investigated. The wear test was carried out with a small test pump with the same specific speed as and a similar structure to that of the deep-sea mining pump. The test results were compared with the numerical calculation results of the deep-sea mining pump obtained by using the same numerical calculation method and wear model, and the test wear area was found to be more consistent with the numerical calculation wear area. The results show that the numerical calculation method used in this article can more accurately predict the surface wear of the passage components of the mining pump and provides a suitable method for the prediction of the wear characteristics of the mining pump.

The correlation between wear evolution and mechanical property degradation of wire rope in a multi-layer winding system

Surface wear is one of the major causes of damage to wire ropes in multi-layer winding systems. This damage leads to performance degradation and affects the service safety of wire rope. To reveal the wear evolution and the performance degradation of wire rope in service, the correlations between the wear characteristic parameters and the residual strength were investigated. The results show that the variation in the wear parameters is affected by the wear distribution and the structure of the wire rope. The main wear mechanisms between wire ropes are adhesion wear and abrasive wear. Different wear parameters should be combined to evaluate the wear state of the wire rope. The tensile temperature rise could accurately reflect the wear evolution of the in-service wire rope under the condition of a large wear degree. The negative correlation between the residual strength and the wear area of the damaged rope samples is the strongest.

Pulsed Magnetic Field Treatment of TiAlSiN Coated Milling Tools For Improved Cutting Performances

In this study a pulsed magnetic treatment was attempted to improve the cutting performance of the TiAlSiN coated WC-12wt%Co cemented carbide end mills and the effects of the strength of the pulsed magnetic field on the cutting forces, the cutting vibrations, the tool wear, the machined surface roughness and mechanical properties were investigated. It is found that the cutting performances of the coated tools are successfully improved with a relatively lower cutting force and less wear area. The average resultant cutting force Fxyave decrease by 14.53% in the last machining process when the optimum processing parameters of 0.5T magnetic field is used, accompanying a maximum decrease of 46.8% in the cutting vibration. The maximum reductions of 57.65% and 25.4% in the flank wear and the average surface roughness of the workpiece are obtained respectively after the treatment. Both the hardness and toughness of the cemented carbides are slightly improved with the imposition of the field. The improvements in the cutting performance of the tool are attributed to the enhanced adhesion strength between the coating and matrix, which is caused by the increased compressive residual stress induced by the PMT.

Wear Characteristics of 22MnB5 Boron Steel under Friction Micro Pin-on-Disks Test

22MnB5 Boron Steel can be considered as emerged material for high strength and low weight application. This material potentially used in abrasive condition such as cutting tool or brake pad where high friction resistance applies. In this study, the wear characteristics of 22MnB5 was investigated under the frictional tests via micro pin-on-disk. 22MnB5 Boron Steel was prepared the form of round shape within the size of 2.6 mm thickness and 12 mm diameter by using laser cutting. 4 different samples were tested namely blank (sample A), self-hardening heat treatment (sample B), 60 HRC hot stamped (sample C) and 70 HRC hot stamped (sample D). The results show that Coefficient of Friction (COF) increased as the hardness of 22MnB5 decreased. Low COF of 0.2114 recorded for sample D with 70 HRC hardness. The COF increased to 0.24, 0.29 and 0.3 when sample C (60 HRC), sample B (52 HRC) and sample A (45.5 HRC) applied respectively. For pin-on disc test, worn area decreased as the hardness increased. 22MnB5 that prepared with the highest hardness of 70 HRC presented smallest wear area of 700 µm x 2400 µm. It is followed by 800 µm x 2400 µm, 1000 µm x 2400 µm, 1600 µm x 2800 µm, when sample C, B and A were scratched. Observation on the worn surface revealed delamination of 22MnB5 surface in the form of fragmented flaking debris.

Enhancing Wear Resistance and Cutting Performance of a Long-Life Micro-Groove Tool in Turning AISI 201

Tool-chip friction increases cutting temperature, aggravates tool wear, and shortens the service life of cutting tools. A micro-groove design of the rake face can improve the wear performance of the tool. In this study, we used the finite element simulation “Deform” to obtain the temperature field distribution of the tool rake face. The size of the micro-groove was determined by selecting a suitable temperature field combined with the characteristics of tool–chip flow in the cutting process, and the tool was prepared using powder metallurgy. The three-direction cutting forces and tool tip temperature were obtained by a cutting test. Compared with the original turning tool, the cutting force and cutting temperature of the micro-groove tool were reduced by more than 20%, the friction coefficient was reduced by more than 14%, the sliding energy was reduced and the shear energy was greatly decreased. According to the analysis of tool wear by SEM (scanning electron microscope) and EDS (energy dispersive X-ray spectroscopy), the crater wear, adhesive wear and oxidation wear of the micro-groove tool were lower than those of the original turning tool. In particular, the change in the crater wear area on the rake face of the original tool and the micro-groove tool was consistent with the cutting temperature and the wear width of the flank face. On the whole, the crater wear area and the change rate of the crater wear area of the micro-groove tool were smaller. Due to the proper microgroove structure of the rake face, the tool-chip contact area decreased, and the second rake angle of the tool became larger. Hence, the tool-chip friction, cutting forces, cutting energy consumption were reduced, tool wear was improved, and the service life of the micro-groove tool was five times longer than that of the original tool.

Integrating object detection and image segmentation for detecting the tool wear area on stitched image

Flank wear is the most common wear that happens in the end milling process. However, the process of detecting the flank wear is cumbersome. To achieve comprehensively automatic detecting the flank wear area of the spiral end milling cutter, this study proposed a novel flank wear detection method of combining the template matching and deep learning techniques to expand the curved surface images into panorama images, which is more available to detect the flank wear areas without choosing a specific position of cutting tool image. You Only Look Once v4 model was employed to automatically detect the range of cutting tips. Then, popular segmentation models, namely, U-Net, Segnet and Autoencoder were used to extract the areas of the tool flank wear. To evaluate the segmenting performance among these models, U-Net model obtained the best maximum dice coefficient score with 0.93. Moreover, the predicting wear areas of the U-Net model is presented in the trend figure, which can determine the times of the tool change depend on the curve of the tool wear. Overall, the experiments have shown that the proposed methods can effectively extract the tool wear regions of the spiral cutting tool. With the developed system, users can obtain detailed information about the cutting tool before being worn severely to change the cutting tools in advance.

Comparative analysis of the wear performance of spindle hook teeth during field work

The wear performance of the spindle hook teeth during field work was compared, and the causes of the wear failure of the spindle hook teeth were analyzed. Samples of three kinds of spindle were obtained from the fixed installation position under continuous field operation conditions. The hardness, phase structure, elemental composition, and micromorphology of the spindle hook teeth were characterized using microhardness, X-ray diffractometer (XRD), energy spectrum analyzer (EDS), and scanning electron microscope (SEM) after cutting of the spindles. Results show that the coating hardness and element penetration zone of No.3 spindle hook tooth are the largest, and the surface coating phase structure of the three kinds of spindle is mainly a body-centered cubic structure of Cr (211). Micro-crack and hole defects exist in the coating of all three kinds of spindle. The thicknesses of the coating of No.1, No.2, and No.3 spindles are 74, 100, and 130 μm, respectively. During the field operation, the wear of the spindle hook tooth coating is caused by abrasive wear and fatigue wear, while the wear of the substrate is the result of the combined effect of abrasive wear and oxidation wear. Extracting the wear area and width of spindle hook teeth shows that the wear area of all three kinds of spindle hook teeth increases exponentially and the wear width changes linearly with the increase in field operation area.