The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform

Y.f. Luo - One of the best experts on this subject based on the ideXlab platform.

  • Rupture failure and mechanical strength of the Electrode Wire used in Wire EDM
    Journal of Materials Processing Technology, 1999
    Co-Authors: Y.f. Luo
    Abstract:

    Abstract In the application of Wire EDM, Wire rupture is very troublesome and impedes further increase of cutting speed. Instead of the spark characteristics or the temperature distribution, the rupture mechanism and the mechanical strength of the Wire are the focus of this investigation. Wire rupture is a mechanical failure in essence, although the process heat has significant influence on the occurrence of the failure. Before the strength analysis, sufficient Wire tension is confirmed as a requirement for Wire bow tolerance rather than being an arbitrary choice. Greater cutting speed demands greater Wire tension to maintain the same small bow error. Tight tolerance and high cutting speed can only be promised at the expense of high mechanical loads on the Wire Electrode. A plane-stress model is used to describe the stress distribution, and the solutions are given as Airy's functions. The yield strength is then analyzed to reveal the influence of the loads and other parameters on Wire yielding. Since Wire fracture occurs frequently in practice, it follows that fracture is emphasized in this investigation. The fracture toughness is evaluated in accordance with the stress-intensity factor as well as with the strain-energy release rate. As far as the yield strength and fracture toughness are concerned, the correlation amongst various parameters including loads, materials properties, and geometrical parameters, is determined. Their effects on Wire strength are revealed quantitatively. In general, Wire tension and spark pressure are the two major causes for Wire rupture. The two loads need to be increased with the increase of cutting speed and the reduction of bow tolerance. Only the careful design of the Wire material and structure can assure the required Wire strength in application especially when high cutting speed is attempted with a tight bow tolerance.

Robert Goodkin - One of the best experts on this subject based on the ideXlab platform.

  • Mechanical failure of the Electrode Wire in deep brain stimulation.
    Parkinsonism & related disorders, 2004
    Co-Authors: A. Alex Mohit, Ali Samii, Jefferson C. Slimp, M. Sean Grady, Robert Goodkin
    Abstract:

    The feasibility and efficacy of deep brain stimulation (DBS) has offered new possibilities for treatment of movement disorders. Mechanical failure of the DBS system is a potential complication. Here we report five patients who presented with mechanical failure of the DBS system. Radiographs of the skull and cervical spine were analyzed for disruptions. Seven instances of lead breakage near the connection of the DBS Electrode with the extension Wire were identified. In one patient this was in the paramastoid area over the skull, while in all others were in the supraclavicular location. The patients consisted of three men and two women ranging in age from 24 to 78 (at the time of first operation), one person suffering three breakages. The length of spanned time from implantation to presentation ranged from 8 to 32 months. Palpation of the Electrode lead Wire in the neck for breakage proved unreliable. Radiography localized the site of breakage in all but one patient who required intraoperative exploration, which revealed that although the lead Wire was disrupted, the two ends remained in contact. The fact that all breakages occurred near the connection Wire suggests that to-and-fro motion of the DBS Electrode with repeated head turning leads to fatigue and eventual disruption.

Hai-wei Chen - One of the best experts on this subject based on the ideXlab platform.

Yoshinori Hirata - One of the best experts on this subject based on the ideXlab platform.

  • Numerical simulation of metal transfer in argon gas-shielded GMAW
    Welding in the World, 2015
    Co-Authors: Yosuke Ogino, Yoshinori Hirata
    Abstract:

    The gas metal arc welding (GMAW) process combines aspects of arc plasma, droplet transfer, and weld pool phenomena. In the GMAW process, an Electrode Wire is melted by heat from an arc plasma, and molten metal at the Wire tip is deformed by various driving forces such as electromagnetic force, surface tension, and arc pressure. Subsequently, the molten droplet detaches from the tip of the Wire and is transferred to the base metal. The arc plasma shape changes together with the metal transfer behavior, so the interaction between the arc plasma and the metal droplet changes from moment to moment. In this paper, we describe a unified arc model for GMAW, including metal transfer. In the model, we do not account for heat transfer in the metal, but the Wire melting rate is determined by the arc current. The developed model can show transition from globular transfer at low currents to spray transfer at higher currents. It was found that electromagnetic force is the most important factor at high currents, but surface tension is more important than electromagnetic force at low currents in determining the transfer mode.

  • influence of shielding gas and Electrode Wire on metal transfer phenomena in gmaw process
    Quarterly Journal of The Japan Welding Society, 2012
    Co-Authors: Keiji Kadota, Yuji Suzuki, Yoshinori Hirata, Tokihiko Kataoka, Rinsei Ikeda, Koichi Yasuda
    Abstract:

    In this paper, metal transfer modes of mild steel Wire of 1.2 mm in diameter, which were observed for welding variables of current, voltage and polarity in Gas shielded Metal Arc Welding process with four kinds of shielding gases (Ar, He, CO2 and mixture gas of Ar+20%CO2) are described. In Electrode positive polarity, metal transfer transition from globular to spray occurs with use of shielding gas of Ar or Ar+20%CO2. But with shielding gas of He or CO2 only globular transfer was observed. In Electrode negative polarity, mild steel Wire added by a very small amount of Rare Earth Metal, which promotes electron emission at the cathode, makes globular to spray transition possible with shielding gas of CO2 or Ar+20%CO2. Other combinations of shielding gas and Electrode Wire result in globular transfer in the current range up to 400 A. In spray transfer mode, current density was estimated to be higher than 1×108 A/m2 at the surface of metal drop onto detachment.

  • Modeling of Molten Drop Oscillation in Gas Shielded Metal Arc Welding
    Materials Science Forum, 2007
    Co-Authors: Yoshinori Hirata, K. Tsujimura, B. Y. B. Yudodibroto, M. J. M. Hermans, I.m. Richardson
    Abstract:

    In Gas shielded Metal Arc Welding process, the molten drop at the Electrode Wire tip is detached and transferred into the weld pool by various driving forces, which have been discussed mainly focusing on gravity force, electro-magnetic force, surface tension force and plasma drag force. In this paper the oscillation phenomena of metal drop and their numerical model are described. The numerical model developed is an axial symmetrical 2D model which enables to calculate and visualize time-change of the drop shape and the flow in the drop using VOF-CSF method. The validity of the model is verified through the comparison between calculations and experiments using waterdrop. It is shown that the natural frequency of the pendant drop decreases with increase of the drop size. And the numerical simulation predicts that it is possible to detach the molten drop from the Electrode Wire by exciting the forced oscillation around the natural frequency with pulsed current.

  • Modelling of the short-circuiting transfer process in GMA welding. A numerical model for metal transfer phenomena in GMA welding
    Welding International, 2005
    Co-Authors: Yoshinori Hirata, T. Oji, T. Osamura, M. Onda, N. Ando
    Abstract:

    During gas metal arc (GMA) welding, such as MAG welding, the welding Wire serves as a welding system Electrode. The Electrode Wire is melted by arc heat to form a metal drop on the Wire tip. Under ...

Dinesh Kumar Shukla - One of the best experts on this subject based on the ideXlab platform.

  • Mathematical modeling of effect of polarity on weld bead geometry in submerged arc welding
    Journal of Manufacturing Processes, 2016
    Co-Authors: Ravinder Singh, Rajiv Kumar Garg, Dinesh Kumar Shukla
    Abstract:

    Abstract Weld bead geometry parameters are significantly affected by polarity as it affects the extent of heat generated at Electrode Wire and work in the welding process which further influences the mechanical and metallurgical properties. Essential requirement of a welding process is to obtain a weld joint with desired weld bead parameters and mechanical properties. In present study mathematical models have been developed to evaluate the effect of polarity on weld bead geometry in submerged arc welding. Response surface methodology has been used for predicting the critical dimension of weld bead geometry and shape relationships at straight polarity and reverse polarity. The developed models have been checked for adequacy and significance by F-test and t-test. Effect of polarity on the response parameters are presented graphically which not only leads to prediction of weld bead geometry and shape relationships but also assisted to achieve the control over weld quality by selecting the appropriate process parameters.

  • Dilution Control by Advanced Submerged Arc Welding
    Advanced Materials Research, 2012
    Co-Authors: Dinesh Kumar Shukla, Sunil Pandey
    Abstract:

    Dilution is a vital element in surfacing and depends on the difference in chemical composition between the weld and the parent metal, the welding process and the technique used. Metal surfacing is becoming the natural choice for reducing the consumption of expensive raw materials, processing cost and proper resource utilization. Mechanical as well as the metallurgical properties are greatly influenced by the degree of dilution. The advanced submerged arc welding (ASAW) process controls the response parameters independently and breaks the fixed relationship between the Wire feed rate (W) and the welding current (I). A study was conducted to investigate the effect of process variables on the dilution during the process. The preheating of the Electrode Wire used in Submerged Arc Welding process (SAW) for surfacing application was done with the modification in the existing setup. Stainless steel 308L Electrode Wire was used on mild steel substrate to study the effect of preheating on the dilution. The results show that ASAW process controls and significantly reduces the percent dilution as compared with the conventional SAW process. ASAW process reduces the heat input, use of consumables and increased productivity, is the added advantages over the conventional process.