The solution of equilibrium positions is a critical component in the calculation of the dynamic characteristic coefficients of aerostatic bearings. The movement of the rotor in one direction leads to bidirectional variations in the air film force, resulting in low efficiency when using conventional calculation methods. It can even lead to iterative divergence if the initial value is improperly selected. This study concentrates on the orifice throttling aerostatic bearings and proposes a novel method called the bivariate interpolation method (BIM) to calculate the equilibrium position. The equilibrium equation for the rotor under the combined influence of air film forces, gravity, and external loads is established. A calculation program based on the finite difference method is developed to determine the equilibrium position. The process of solving the equilibrium position and the convergence is compared with the secant method and the search method. Furthermore, the variation trend of the equilibrium position and stiffness when the external loads changes are studied based on the BIM. Finally, the correctness of the BIM to solve the equilibrium position is proved by comparing it with the experiment results. The calculation results indicate that the BIM successfully resolves the problem of initial value selection and exhibits superior computational efficiency and accuracy. The equilibrium position initially moves away from the direction of the external load as the load increases, and then this gradually approaches the load direction. The main stiffness increases with increases in the external load, while the variation in cross stiffness depends on the direction of the external load.

Intense research efforts are focused on the development of advanced high-entropy alloys intended for premium aerospace components and other applications, where high strength and good formability are crucial. The mechanical properties of these alloys are closely related to the phase transformation, dislocation evolution, and grain size, and these factors are affected by the deformation temperature. The response of the retained austenite to strain-induced martensitic transformation at various temperatures was studied in an advanced Ti₆₈Nb₇Ta₃Zr₄Mo₁₈ (at.%) high-entropy alloy via molecular dynamics simulation. It was found that the Ti₆₈Nb₇Ta₃Zr₄Mo₁₈ alloy changes from a single crystal to a polycrystal during the tensile process, and the transition of the Ti₆₈Nb₇Ta₃Zr₄Mo₁₈ (at.%) high-entropy alloy from the BCC phase to the FCC phase occurs. At high temperatures and low strain rates, grain boundary slip is the main deformation mechanism, and at low temperatures and high strain rates, dislocation slip replaces grain boundary slip as the dominant deformation mechanism, which improves the strength of the alloy. Moreover, when the grain size is too small, the strength of the alloy decreases, which does not satisfy the fine grain strengthening theory and shows an inverse Hall–Petch relationship. This study offers a new compositional window for the additive manufactured lightweight high-strength material categories for various applications including the aerospace industry.

The contact interface between the stator and the rotor tip of the spindle could be destructed when the spindle is rotating continually at high speed, which will cause strong noise and severe vibration. In order to reduce the sound pressure level of the noise generated by the rotating spindle, three different coating materials, that is, Al-Ti-Cr-C, Ti-C and DLC, were applied to the rotor tip surface of the spindle. The effects of the coating materials on the sound pressure levels of the rotating spindles were studied by using the treated spindles and the untreated spindles. Results showed that compared with Coating Al-Ti-Cr-C, the Coating Ti-C containing only the two main elements of Ti and C produces the smallest sound pressure level in the experiment speed range; the surface roughness of Coating DLC is smaller, but the sound pressure level of the entire spindle becomes larger than Coating Ti-C; the sound pressure level of the spindles with surface coating treatment is obviously lower than that of the spindles without coating treatment. The research results can provide basic data for the design and production of noiseless spinning spindles.

As the core component of ultra-precision machine tools, the manufacturing errors of aerostatic spindles are inevitable due to the limitations of machining and assembly processes, and these errors significantly affect the spindle’s static and dynamic performance. To address this issue, a force model of the unbalanced air film, considering the straightness errors of the rotor’s radial and thrust surfaces, was constructed. Unlike conventional studies that rely solely on idealized error assumptions, this research integrates actual straightness measurement data into the simulation process, enabling a more realistic and precise prediction of bearing performance. Rotors with different tolerance specifications were fabricated, and static performance simulations were carried out based on the measured geometry data. An experimental setup was built to evaluate the performance of the aerostatic spindle assembled with these rotors. The experimental results were compared with the simulation outcomes, confirming the validity of the proposed model. To further quantify the influence of straightness errors on the static characteristics of aerostatic spindles, ideal functions were used to define representative manufacturing error profiles. The results show that a barrel-shaped error on the radial bearing surface can cause a load capacity variation of up to 46.6%, and its positive effect on air film load capacity is more significant than that of taper or drum shapes. For the thrust bearing surface, a concave-shaped error can lead to a load capacity variation of up to 13.4%, and its enhancement effect is superior to those of the two taper and convex-shaped errors. The results demonstrate that the straightness errors on the radial and thrust bearing surfaces are key factors affecting the radial and axial load capacities of the spindle.

As a key component of the Tempcore process, the Tempcore cooler plays a critical role in enhancing the cooling efficiency of steel bars. A cylindrical corrugated tube designed specifically for the Tempcore cooling process of large diameter steel bars, where the corrugated surface induces turbulence to enhance cooling efficiency. The influence of its structural parameters on the cooling performance was investigated through a combination of numerical simulations and experimental validation. First, based on the law of mass conservation, the influence of structural parameters of the corrugated tube on their internal flow field was analyzed. Then, a simulation model of the Tempcore cooler was developed to explore the variation in steel bar cooling efficiency under different structural parameters. The results show that increasing the maximum inner diameter of the corrugated tube enhances cooling efficiency, which subsequently tends to stabilize. With increasing minimum inner diameter and pitch, the cooling efficiency of the bars first increases and then decreases. And based on the influence of individual parameters, an orthogonal simulation was performed to identify the optimal corrugated tube structural configuration for achieving maximum cooling efficiency. The minimum inner diameter was identified as a critical factor influencing the heat transfer efficiency of the steel bar. Finally, based on the results of orthogonal simulations, five corrugated tubes were fabricated and integrated into the Tempcore cooler for experimental validation. The accuracy of the simulation was verified through microstructural analysis of the produced steel bars, which exhibited a 38% increase in martensite volume fraction. The designed corrugated tubes significantly improve the cooling efficiency of the Tempcore process without requiring an upgrade to the water supply system capacity.

Aerostatic spindles are indispensable in the ultra-precision manufacturing field due to their high accuracy and low friction. However, rotor manufacturing errors will affect the thickness and uniformity of the air film, thereby limiting the improvement and application of the aerostatic spindle. To explore this issue, this paper presents theoretical modelling and experimental work. Rotor cylindricity errors were first evaluated based on manufacturing errors, and a calculation model of the film thickness considering rotor cylindricity errors was established. By solving the dynamic Reynolds equation considering cylindricity errors, the dynamic stiffness and damping of aerostatic spindles were obtained. The influence mechanism of rotor cylindricity errors on the dynamic stiffness and damping coefficients of the rotor–bearing system was revealed. The stiffness coefficients K_xx, K_yy, and K_xy are more sensitive to the saddle-shaped errors, and the stiffness coefficient K_yx and both damping coefficients are more closely related to bucket-shaped errors. Regarding the influence of the cylindricity errors’ extremal position, the main and cross stiffness coefficients are sensitive to saddle-shaped errors and bucket-shaped errors, respectively; the main and cross-damping coefficients are sensitive to bucket-shaped errors. Under the effect of three kinds of error shapes, when the rotor cylindricity errors value is less than 1 μm, the dynamic stiffness and damping coefficients are conducive to improving the dynamic characteristics of the rotor–bearing system. Multiple rotors were manufactured, and their cylindricity errors were measured, and then the dynamic characteristics of the assembled aerostatic spindles with these rotors were tested. It was found that the dynamic stiffness of spindles with saddle-shaped errors is larger than that of spindles with conical-shaped errors, and the greater the error values are, the worse the rotation accuracy. The experimental results are consistent with the theoretical findings, thus verifying the feasibility and validity of the established theoretical model. This study improves the error tolerance design accuracy of rotors and thereby enhances the dynamic performance of aerostatic spindles.