Improving Performance of Laser and Shaped Tube Electrochemical Machining by Using Retracted Hybrid Tubular Tool Electrode

The coaxial laser has been introduced to shaped tube electrochemical machining (STEM), referred to as Laser-STEM, to enhance the materials removal rate and precision. To address the issue of central residual formation during the Laser-STEM process, which limited the machining stability and feeding rate, the retracted hybrid tubular electrode was applied. The formation mechanisms and effects of the W-shaped central residual were analyzed. Simulation and experiments were conducted to study the impact of the retracted length of the tubular electrode. Simulation results showed that a retracted length of 1-1.5 mm of the inner low-refractive layer could improve the electric current density distribution homogeneity to remove the W-shaped central residual in the machining area. The electric current density distribution homogeneity in the machining zone has been decreased by 38% by utilizing the hybrid tubular electrode with a retracted length of 2.0 mm. With a proper retracted length, the laser coupling efficiency exceeded 74.5%. Hence, the retracted hybrid tubular electrode could act as both the tool electrode and optical waveguide in the Laser-STEM process. Experimental results proved that the machining efficiency and precision of Laser-STEM could be enhanced by utilizing the retracted hybrid tubular electrode. With the retracted length deg rising from 0 mm to 1.5 mm, the maximum feeding speed increased by 373%, and the machining precision was improved by 42.2%. The maximum feeding rate of 4.1 mm/min has been achieved using the retracted hybrid tubular electrode in the Laser-STEM process, which has been improved by 105%, compared with the available maximum feeding rate of the tubular electrode in the STEM process. Finally, the small holes with a diameter of 1.4 mm and an aspect ratio of 15 have been processed by Laser-STEM with the retracted hybrid tubular electrode.

A tubular electrode assembly reactor for enhanced electrochemical wastewater treatment with a Magnéli-phase titanium suboxide (M-TiSO) anode and in situ utilization

A stainless steel pipe (SSP) was used as a cathode. A tubular Magnéli-phase titanium suboxide (M-TiSO) anode was posited in the center. A spiral static mixer was used to process intensification.

Long-length tubular Electrode-Tools from Composite Material for Electrical Discharge Machining of Hard Alloys

The article deals with long-length tubular electrode-tools made of the engineered composite [(WC+3wt%Co)+3wt%BN)]+14wt%Cu, which, during electrical discharge piercing of holes in a hard alloy WC+6wt%Co (ISO 513:2012) in the optimal mode, have a productivity that is almost 8 times higher than the productivity of the process, when it is performed using copper electrode-tools. Therewith, electrical discharge wear of the electrode-tools made of the new material is 4.1 ... 4.5 times less than the wear of the copper electrode-tools. To obtain hollow electrodetools from the specified material, the powder composition was radially molded by the pressure of a impulsed magnet field, and the resulting porous blank was impregnated with copper during its further sintering.

Comparison of Properties of Hardfaced Layers Made by a Metal-Core-Covered Tubular Electrode with a Special Chemical Composition

In this article, the results of research on the metal-mineral-type abrasive wear of a wear-resistant plate made by a tubular electrode with a metallic core and an innovative chemical composition using the manual metal arc hardfacing process were presented. The properties of the new layer were compared to the results of eleven wear plates manufactured by global suppliers, including flux-cored arc welding gas-shielded (FCAW-GS, Deposition Process Reference Number: 138), flux-cored arc welding self-shielded (FCAW-SS, Deposition Process Reference Number: 114), automated hardfacing, and manual metal arc welding (MMAW, Deposition Process Reference Number: 111) hardfacing T Fe15 and T Fe16 alloys, according to EN 14700:2014. Characterization of the hardfaced layers was achieved by using hardness tests, optical microscopy, confocal microscopy, scanning electron microscopy, and EDS (Energy Dispersive Spectroscopy) and X-ray diffraction analyses. Based on wear resistance tests in laboratory conditions, in accordance with ASTM G65-00: Procedure A, and surface layer hardness tests, in accordance with PN-EN ISO 6508-1, the wear plates most suitable for use in metal-mineral conditions were chosen. The results demonstrated the high metal-mineral abrasive wear resistance of the deposit weld metal produced by the new covered tubular electrode. The tubular electrode demonstrated a high linear correlation between the surface wear resistance and the hardness of the metal matrix of the tested abrasive wear plates. In addition to hardness, size, shape, the dispersion of strengthening phases, and the base metal content, depending on hardfacing technology and technological parameters, impact wear resistance is represented by volumetric loss caused by effect-free or constrained dry abrasive medium contact. The presented results can be used in machine part material selection and wear planning for applications in inspection, conservation, and regeneration interval determination. The obtained results will be applied in a real-time wear rate prediction system based on the measurement of the working parameters.

3D-PIV Measurement for EHD Flow of Spiked Tubular Electrode Corona Discharge in Wide Electrostatic Precipitator

The electrohydrodynamic (EHD) flow induced by a corona discharge has an important influence on the movement and collection of fine particles in an electrostatic precipitator. In this paper, three-dimensional particle image velocimetry (3D-PIV) is used to investigate the impact of different primary flow velocities and applied voltage on diffusion and transport of the spiked tubular electrode corona discharge EHD flow in a wide type electrostatic precipitator. In order to measure the flow characteristics of different positions of a spiked tubular electrode, the PIV measurements are carried out in several cross-sectional planes along the ESP duct. From 2D flow streamlines, in plane 1 (where the tip of the spike is oriented in the direction of primary flow), the velocity of the counter-clockwise vortex caused by the EHD flow near the plate decreases as the primary flow velocity increases. However, in plane 3 (where the tip direction is opposite to the primary flow), two vortices rotate adversely, and the flow velocity of the clockwise vortex near the plate increases as the primary flow velocity increases. Flow velocity increasing near the plate makes the particles deposited on the plate more easily to be re-entrained. It can be found in the three-dimensional analysis of the flow field that there are mainly “ascending vortex” and downward tip jet in the three observation planes. There is a discrepancy (in terms of distribution region and the magnitude of velocity) between the three-dimensional characteristics of these vortices and tip jets in the different cross-sectional planes.