Aerostatic bearings are the critical parts of ultra-high speed spindles applied to precision milling, grinding, and other precision engineering applications. In this paper, the computational design and analysis of aerostatic journal bearings at ultra-high speed spindles are investigated particularly in light of the nonlinear compressible Reynolds equation and the associated computational analysis and algorithms using the finite element method-based Galerkin weighted residual method. The steady-state static and dynamic behaviors of aerostatic journal bearings are systematically studied, including pressure distributions, load capacity, stiffness, attitude angle, and volume flow rate under conditions of various operating speeds and eccentricity ratios. The coupling of the aerostatic and aerodynamic effects within ultra-high speed aerostatic journal bearings is further explored. The obtained results are formulated as design guidelines for aerostatic journal bearings applied to air-bearing spindles operating in high precision and ultra-high rotational speeds.

This paper presents a novel approach to measure the cutting temperature in process and control it to some extent by using an internally cooled smart cutting tool with a closed internal cooling circuitry. Numerical modeling based on the finite element analysis-computational fluid dynamics (CFD) method is carried out by using ansys and fluent, then the surface temperature distribution of the tool is fitted and the equivalent heat transfer coefficient of the tool surface contacting with cooling fluid is computed. Analytical thermal model of the tool is established based on the lumped parameter method. Theoretical analysis and numerical simulation results are in good agreement, which demonstrate that the innovative smart tooling design concept can effectively sense the cutting temperature at the cutting tool tip in process and also be used to reduce and control the critical cutting temperature in cutting zone for adaptive machining of difficult-to-machine materials, such as titanium and Inconel alloys. Experimental cutting trials are carried out to further examine and validate the method and concept of applying the smart cutting tool system.

The research presented in this article aims at developing an innovative integrated modelling methodology to quantify the energy consumption and equivalent carbon footprint in the grinding process. This article categorizes the energy consumption in four compositional parts and identifies the associated key factors affecting the energy consumption and equivalent carbon dioxide emission during the grinding process. Considering energy consumption (E), resource utilization (R), waste generation (W) and their collective effect on equivalent carbon dioxide (C) emission (ERWC), quantitative analysis modelling of the entire grinding process is developed against the roughing, finishing and spark-out stages of the process. The modelling and simulation analysis are carried out with the MATLAB environment, supported by the evaluation and validation through well-designed grinding trials.

This article presents a novel smart turning tool using the embedded piezoelectric sensors for real-time measurement of cutting forces in precision turning operations. The innovation is built with piezoelectric sensor array in the tool shank so as to obtain a smart turning tool, which is robust, industrial feasible and refittable and integrated with adequate measurement accuracy and in-process sensing capability. In the design, four pieces of piezoelectric sensors as an array are integrated into the specially designed tool shank, which directly generate charges under cutting forces. The four charge output signals can be amplified, acquired and processed through decoupling to deduce out the cutting forces with measurement decoupling algorithms. The tool calibration and performance testing are carried out using well-designed cutting trials to further evaluate and validate the tool design in an industrial feasible manner.

Continuous improvement of the component roundness accuracy through computer numerical control centreless grinding in high productivity is one of the most important issues particularly for modern automotive and bearings manufacturing. For instance, the process is towards 0.1–0.3 µm roundness accuracy in grinding the engine valve rod because of the increasingly stringent energy efficiency requirement in automotive engines. The characteristics of the computer numerical control centreless grinding process make it challenging, that is, how to assure the workpiece roundness generation in a predictable, producible, highly productive and scientific manner. In this article, a simulation-based industrial feasible approach is presented to model and control the workpiece roundness generation and its perfection strategies in computer numerical control centreless grinding. The kinematics of the workpiece in the process is presented according to the workpiece profile and its geometric configurations. Taking into account the workpiece geometric movements, contact and loss effect and grinding restrictions, a time-domain dynamic model is developed to provide the dynamics description of the workpiece, the grinding wheel and the control wheel in the process. The roundness generation of the workpiece is further predicted using this model. The effects of multiple factors on the workpiece rounding process are discussed and the influences on final roundness errors are investigated.

Hydrostatic bearing spindles are widely applied in high precision grinding and turning machines due to their good dynamic stability and rotational accuracy. However, under the condition of high-speed rotations, the heat generated by the friction of the oil film will cause the shear thinning effect. It not only reduces the rotation accuracy of the spindle but also reduces the service life of the spindle. The surface texture structure and configuration between the planes play the role of homogenizing oil film temperature and preventing the bearing surface wear caused by excessive concentration of temperature, which can change the relative motion from the inside of the oil film and thus improve the performance of the hydrostatic spindle more effectively. In this paper, the influence of the surface texture shape and height on the thrust bearing performance of the hydrostatic spindle is systematically investigated by comparative analysis. The CFD simulations are developed to analyze the computational results based on the theory of viscosity-temperature characteristics. The results show that when the height of the surface structure is 1 ~ 2 times the oil film thickness, the spindle bearing performance is the best. The average temperature in the bearing region is the lowest and the accuracy of the simulations was verified by experimental results.