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This paper focuses on the study of the induction heating process of a camshaft in a marine diesel engine. A three-dimensional finite element model for dynamic induction heating is established using the finite element method of multi-physical field coupling, aiming to investigate the temperature uniformity of the cam during this process. Three elements are analyzed in this study: the moving speed, the gap between the induction coil and the workpiece, and the width of the induction coil. These factors allow for an analysis of the temperature distribution in the thickness direction and contour line direction of the cam under various conditions. On this basis, an equivalent parameter about the temperature uniformity in the thickness direction of the cam is proposed to guide the selection of the camshaft induction heating process parameters. [ABSTRACT FROM AUTHOR]

As the main components of mechanical products and important transmission components of mechanical motion, shaft workpieces (SW) need to undergo high-speed motion while also withstanding high torque motion, which has high processing requirements. At the same time, the processing quality of the workpieces determines the success of the entire processing process, and the quality-inspection methods and the accuracy of the technology directly affect the evaluation of the product. This paper designs an intelligent detection system for the surface shape error (SSE) of SW that combines multiple sensors. Based on the principle of sensor use and specific experimental status, the overall scheme of the detection system is designed, followed by research on the spatial positioning algorithm and surface measurement algorithm of the workpiece to be tested. We then compensate and correct the errors with the algorithm. The effectiveness of the system is verified by measuring the surface size of the workpiece. Finally, the radial circular runout error is taken as an example to verify the detection system. The results show that the measurement error is less than 5%, and the accuracy of the system is high. [ABSTRACT FROM AUTHOR]

A nanosecond laser is used to fabricate groove-patterned textures on the upper surface of Ti-6Al-4V alloys, and then molybdic sulfide solid lubricants are filled into the grooves. The treated titanium alloy is subjected to friction and wear tests. The tribological performances of Ti-6Al-4V alloys are evaluated, and the wearing mechanism is analyzed. The combination of solid lubricants and surface texturing can effectively reduce the frictional coefficient and reduce the adhesion of Ti-6Al-4V materials on the steel balls for friction. The main wearing mechanism is the adhesive wear of the Ti-6Al-4V alloy and the adhesion of Ti-6Al-4V alloy materials on the surface of the steel balls. During the friction process, solid lubricants are squeezed from the grooves and coated at the friction interface to form a solid lubrication layer. This is the important reason why the combination of surface texturing and solid lubricants can improve the friction properties of titanium alloys effectively. The combination of solid lubricants and laser surface texturing provides an effective alternative way to improve the tribological properties of titanium alloy materials. [ABSTRACT FROM AUTHOR]

Vitrified bond cubic boron nitride (CBN) grinding wheel specimens with controllable porosity were prepared by regulating the pore former dextrin content and varying the forming pressure, and the performance of the grinding camshaft was studied. The porosity of the specimens increases with the increase in dextrin content, and decreases first and then increases with the increase in the forming pressure. The grinding experiments show that the dextrin content is negatively correlated with the grinding force and grinding temperature, while the grinding force and grinding temperature of the specimens increase and then decrease with the increase in the forming pressure. When we observe and measure the grinding surface of the specimen and workpiece, we see that the surface roughness of the specimen after grinding is smaller than that before grinding. In addition, the greater the porosity of the specimen, the rougher the surface of the workpiece after grinding. [ABSTRACT FROM AUTHOR]

The design of an optically transparent and flexible metamaterial absorber was presented and fabricated. For this purpose, we use two different patterned silver nanowire films separated by the space layer, forming a transparent sandwiched structure with an ultrathin thickness. By analyzing the equivalent circuit model and distribution of electric field and current, the absorption physical mechanism has been theoretically investigated. The results show that the structure can achieve above 0.8 absorptions from 6 GHz to 18 GHz, and at the same time, this absorber also can obtain wide-angle property. The optical transmittance of the fabricated absorber exceeds 82% in the visible band. The results demonstrate that transparency and flexibility are the additional benefits that make the proposed absorber suitable for various potential applications. [ABSTRACT FROM AUTHOR]

In this paper, a photo-excited switchable terahertz metamaterial (MM) polarization converter/absorber has been presented. The switchable structure comprises an orthogonal double split-ring resonator (ODSRR) and a metallic ground, separated by a dielectric spacer. The gaps of ODSRR are filled with semiconductor photoconductive silicon (Si), whose conductivity can be dynamically tuned by the incident pump beam with different power. From the simulated results, it can be observed that the proposed structure implements a wide polarization-conversion band in 2.01–2.56 THz with the conversion ratio of more than 90% and no pump beam power incident illuminating the structure, whereas two absorption peaks operate at 1.98 THz and 3.24 THz with the absorption rates of 70.5% and 94.2%, respectively, in the case of the maximum pump power. Equivalent circuit models are constructed for absorption states to provide physical insight into their operation. Meanwhile, the surface current distributions are also illustrated to explain the working principle. The simulated results show that this design has the advantage of the switchable performance afforded by semiconductor photoconductive Si, creating a path towards THz imaging, active switcher, etc. [ABSTRACT FROM AUTHOR]

The hard turning process has been widely used in the field of hard material precision machining because of its high efficiency, low processing residual stress, and low environmental pollution. Due to its undesirably processing quality, it is still not a substitute for traditional grinding, so many studies have reported that the process has been optimized. However, there has been little research on the geometry optimization of hard cutting tools, which have a great influence on the traditional machining process. In this paper, two tools with different rake face shapes are designed. The finite element analysis method is used to compare their performance with a conventional plane tool while turning hardened steel. The results show that the cutting performance of the designed tool T1 and T2 (chip morphology, cutting force, and cutting temperature) and the quality of the machined surface are improved compared with the tool. The cutting force decreased by 12.72% and 14.74%, the cutting temperature decreased by 7.56% and 9.01%, respectively, and the surface residual stress decreased by 26.56% and 28.66%. [ABSTRACT FROM AUTHOR]

Vitrified bond cubic boron nitride (CBN) grinding wheel specimens with controllable porosity were prepared by regulating the pore former dextrin content and varying the forming pressure, and the performance of the grinding camshaft was studied. The porosity of the specimens increases with the increase in dextrin content, and decreases first and then increases with the increase in the forming pressure. The grinding experiments show that the dextrin content is negatively correlated with the grinding force and grinding temperature, while the grinding force and grinding temperature of the specimens increase and then decrease with the increase in the forming pressure. When we observe and measure the grinding surface of the specimen and workpiece, we see that the surface roughness of the specimen after grinding is smaller than that before grinding. In addition, the greater the porosity of the specimen, the rougher the surface of the workpiece after grinding.