Research on 3D chatter stability of blade by high-speed turn-milling

High speed turn-milling is regarded as the milling of a curved surface while rotating the workpiece around its centre point, which combines effectively the advantages of both turning and milling, wherein allows for good metal removal with the difficult-to-cut thin-walled workpieces in aviation. The objective of the present work is to study chatter stability of thin-walled blade by high-speed turn-milling in cutting condition. The dynamic model and the stability critical condition determined by the relative dynamic characteristics between cutter subsystem and blade subsystem are put forward. Aiming at the small-stiffness frequency response characteristics of thin walled structures, the stability critical domain is predicted based on the high-order dynamic behavior of the multi-DOF system. It can be shown that the chatter condition in turn-milling is closely related to both cutter speed and depth of cut, besides cutter geometry, engagement conditions, frequency response function, material property of workpiece and so on. Based on chatter stability simulation model to access 3D chatter stability lobes of high-speed turn-milling machining blades. This conclusion provides a theoretical foundation and reference for the orthogonal turn-milling mechanism research

Research on Cutting Force of Turn-Milling Based on Thin-Walled Blade

Turn-milling is regarded as the milling of a curved surface while rotating the workpiece around its center point, which combines effectively the advantages of both turning and milling, wherein it allows for good metal removal with the difficult-to-cut thin-walled workpieces in aviation. The objective of the present work is to study cutting force by turn-milling in cutting condition. Aiming at the deformation properties of thin-walled blade, the predicted models of rigid cutting force and flexible cutting force with ball cutter are provided, respectively, in turn-milling process. The deformation values of blade and cutter are calculated, respectively, based on the engaged trajectory by using the iterative algorithm. The rigid and flexible cutting forces are compared and the influence degrees of cutting parameters on cutting forces are analyzed. These conclusions provide theoretical foundation and reference for turn-milling mechanism research

Enhancing the selectivity of frequency selective surfaces for terahertz sensing applications

This paper introduces a new technique for enhancing the selectivity (or the quality factor, Q-factor) of frequency selective surfaces (FSS) for sensing applications. The proposed FSS functions as a free-space bandpass resonator, designed to sense the changing dielectric properties of minute amount of materials loaded on the FSS. The Q-enhancement technique is mainly based on two concepts; enhancing the field concentration in a given area and introducing transmission zeros in the FSS response. Two designs based on a modified complementary split-ring resonator (CSRR) at 300 GHz have been proposed. The first one is composed of complementary triple-split ring resonators. The splits divided the structure into arcs of different lengths. As a result, the transmission zero is obtained in the passband due to a destructive coupling. This produces a resonance Q-factor of 41. By controlling the orientation of the three splits, higher Q-factor of 84 is attainable. The second structure is designed using concentric triple-split rings. The added electromagnetic coupling between the concentric rings makes the transmission response steeper as compared with the single triple-split ring, and the quality factor increases from 41 to 90. By reducing the inter-spacing distance by three times, the Q-factor can be further increased to 256. The parameter studies of the FSS structures based on full-wave simulations have been presented