Search Results (3)

The periodic nanotexture was superposed to the micro-textured grooves on the side surface of the punch. These grooves with nanotextures were shaped to have parallel and vertical orientations to the punch stroke direction, respectively. A stack of five amorphous electrical steel sheets was punched out with these micro-/nano-textured punches. The process affected zone at the vicinity of the punched hole was analyzed by SEM (Scanning Electron Microscopy) and a three-dimensional profilometer. The punch surfaces were also observed by SEM to describe the debris particle adhesion on them. The dimensional change in each layer of the stack before and after perforation was measured to describe the punching behavior with the comparison to the punch diameter. Full article

The amorphous alloy transformer has a smaller coercive force and lower specific iron loss. It precedes the conventional silicon steel sheet transformer from the perspective of energy conservation. However, amorphous alloy material has a more significant magnetostriction coefficient, resulting in stronger vibration and acoustic noise. This paper investigates the measurement, analysis, and improvement of vibroacoustic characteristics of one three-phase, four-frame amorphous alloy distribution transformer to reduce environment noise pollution. This study adopts a coupling analysis method of magnetic–force–acoustic multi-physical fields to analyze the vibroacoustic characteristics. It then introduces a novel combination method of magnetic field analysis and an electric circuit to improve the efficiency of magnetic field analysis. This new combination method can greatly reduce the solution time of multiple physical fields through comparison with the traditional field-circuit coupling method. Different from other studies, this paper studies the acoustic and vibration characteristics of an amorphous alloy transformer under both no-load and load conditions. It is found that the load vibration noise of an amorphous transformer is more severe than that of a traditional silicon steel transformer. Accordingly, the study measures the vibroacoustic characteristic with different excitations and load levels under different working conditions to verify the numerical analysis method. Furthermore, according to the analysis results, this paper suggests a few vibration and noise control strategies. In conclusion, the paper deduces an essential basis for exploring strategies of vibration reduction and noise control for amorphous alloy distribution transformers. Full article

A CVD (Chemical Vapor Deposition) diamond coated tungsten carbide (WC) and cobalt (Co) sintered alloy punch was trimmed by the femtosecond laser machining to sharpen its edge with about 2 μm and to simultaneously make nanostructuring to its side surface. In addition to the sharpened edge, its edge profile was formed to be homogeneous enough to reduce the damage layer width by piercing the electrical amorphous steel sheet stack. Each brittle sheet in the stacked work was damaged to have three kinds of defects by piercing; e.g., the droop-like cracking in the thickness and at the vicinity of hole, the wrinkling in peak-to-valley with partial cracking on the peaks, and the circumferential cracking. When using the WC (Co) punch with the inhomogeneous edge profile in the sharpened edge width, these three damages were induced into each sheet and the maximum damage width exceeded 80 μm. When using the punch with the sharpened edge and homogeneous edge profile, the wrinkling mode was saved and the total affected layer width was significantly reduced to less than 20 μm. Through the precise embossing experiments, this effect of punch edge profile condition to the induced damages was discussed with a statement on the nanostructuring effect on the reduction of damaged width in electrical amorphous steel sheets. The developed tool with the sharpened edge and homogenous edge condition contributes to the realization of a low iron loss motor with a reduced affected layer width. Full article