Papers by Keyword: Pulse

Abstract: This paper present an investigation on cutting speed of ultrasonic vibration assisted wire electrical discharge machining (US-WEDM) for High carbon high chromium D3 Steel. An extensive research study was carried out with an aim to select the optimum cutting condition with the varying amplitude of vibration in order to get the optimum cutting speed for the proposed set-up. The process was mathematically modeled using the response parameters, i.e. cutting speed under a range of control parameters and the main influencing factors were determined for cutting speed criteria Taguchi’s experimentation methodology indicated the contribution of amplitude of vibration (P=6.16%), pulse on time (P=14.54%), pulse off time (P=73.16%) and peak current (P=5.94%). Finally, the optimum parametric setting for different cutting speed arising out of study has synthesized as amplitude of vibration at level 3 (18μm), peak current level 1 (100 units), pulse on time level 2 (118 μ sec) and pulse off time level 2 (46 μ sec) and analyses in this study.

Abstract: General idea of mathematical simulation is set. Equations that describe hydraulic power pulse machine operation are described. Restriction factors are identified; they are included in mathematical model simulation. Mathematical simulation results are shown for essential parts of machine. Results of hydraulic power pulse machine mathematical simulation are presented.

Abstract: In the present study, several series of pulse current electrodeposition experiment have been carried out at 25 °C in various electrolyte bath under different current densities to find the suitable electrodeposition condition for fabricating Mn-Cu alloys coating. The deposition kinetic of Mn-Cu alloy was assessed from the measurement of cathodic polarization behavior in selected electrolyte bath. The uniformity of Mn-Cu alloy coating, and its composition were studied by scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS) analysis. The results shows that a dense, adherent, smooth and uniform Mn-Cu alloy coating can be deposited on SUS 430 substrate with relatively high deposition rate. The evaluation of coating area specific resistance (ASR) at 700 °C shows a value of 0.04 Ωcm². This result indicates that Mn-Cu alloy is promising as alternative coating materials for SOFC interconnect.

Abstract: We have investigated the influence of the modes of adaptive pulse-arc welding and surfacing on the structure and physical-mechanical properties of welded joints of steel 09Mn2Si and the surfaced composition of this steel coated with a modified powder material of chromium carbide with the submicrocrystalline structure. It is shown that the pulsed mode of welding and surfacing can improve the homogeneity of the structure of the welded joint of steel and a surfaced coating and reduce the grain size of metals in both of them. Structural changes lead to an increase in ductility and toughness of the weld metal.

Abstract: In the present work, Zn-ZrO₂ nanocomposite coatings were deposited on the copper substrate through DC and pulse electrodeposition technique with low current density (10 mA/cm²). The effect addition of ZrO₂ nanoparticles and pulse current were studied. The surface morphology, microhardness and erosion resistance of Zn-ZrO₂ nanocomposite coating were evaluated. The result shows that, with the addition of ZrO₂ particles, the surface morphology of Zn-ZrO₂ nanocomposite coating was smoother. Phase identification by XRD confirm that Zn layer had been sucessfully deposited. The presence of ZrO₂ nanoparticles was not detected. Compared to DC, pulsed current electrodeposition technique showed higher cathodic efficiency, better microhardness and good erosion resistance.

Abstract: With the help of an Assisting Electrode (AE), non-conductive ceramics can be machined using Electrical Discharge Machining (EDM) process. The AE helps start the EDM process and the intrinsic conductive layer (ICL) ensures that the electrical contact between the workpiece and the generator is maintained. However, the understanding of EDM process of non-conductive ceramics is limited due to the typical characteristic of the process: the geometric dimension of the discharge region is limited to few micrometers and the duration of the dielectric discharge is in the range of few microseconds making it difficult to directly observe the spark and the associated crater formation phenomenon. Analyzing the electrical signals during the EDM process could provide an insight of the process. This paper presents a study on analyzing the electric pulses occurring during the EDM process of a conductive workpiece (copper) and a non-conductive workpiece (Si₃N₄ ceramics). Typical pulses occurring during the EDM of a metal and a non-conductive ceramics are identified with the signal recorded at a sampling rate of 2.5 GS/s. Sampling rate of 25 MS/s is used to monitor the pulses occurring while machining a hole with depth of 1 mm. The pulses during EDM of non-conductive materials are significantly different than those during EDM of metals. Four most outstanding differences have been identified in terms of the ringing behavior of the voltage signal, the recharge time required to reach the set value of open voltage, the presence of the reverse current and the value of the peak current detected in case of Si₃N₄. The pulses monitored with lower sampling frequency was characterized and discriminated into sparks, arcs and short circuits. The percentage of the discriminated pulses for varying machining depth of the test structure has been presented.

Abstract: The model of a hydraulic pulse system of drilling machines is presented in this paper. Differential equations that characterize the processes run in the system are obtained. A new method for pressing a hydraulic cylinder with a pneumatic feeder is also suggested.

Abstract: It is now possible to formulate the relation of the linear size of cracking arising on welding the cylindrical homogeneous-metal. Mathematical simulation of metal crystallization on welding and micro structural analysis give an insight into the fact that there begins crack nucleation in a weld root. Experimentally, by means of Acoustic Emission (AE), one can study welding and obtain the amplitude distribution of AE signals from cracking against the background of the hindrance accompanying this process. The conditions were found making impossible cracking.

Abstract: In this research power rock cutting mechanisms are considered. Impact and vibratory impact mechanisms are presented, their design characteristics are given. The new peenless power pulse hydraulic mechanism is considered, its operating principle is described, and the schematic diagram is provided. The new system can be used at building of the new rock-drilling machines with a hydraulic actuator for the intensification of the process of rocks destruction.

Abstract: Thispaper designs a set of experiment system for stepper motor, the control system ofstepping motor is composed of stepper controller, drive and stepper motor, withthe single chip processor as the stepper motor controller to realize the morecomplex stepper motor control function. This system has got good teachingeffect in experiment teaching.