The Experts below are selected from a list of 10065 Experts worldwide ranked by ideXlab platform

Primoz Podrzaj - One of the best experts on this subject based on the ideXlab platform.

  • resistance spot weld strength estimation based on Electrode Tip displacement velocity curve obtained by image processing
    Science and Technology of Welding and Joining, 2014
    Co-Authors: Samo Simončič, Primoz Podrzaj
    Abstract:

    This paper presents a machine vision based Electrode Tip displacement measurement. The displacement is obtained by the observation of a certain area (mask) in a sequence of images. Based on the obtained displacement measurement a Tip velocity was calculated as well. For this signal Kalman filtering was used in order to reduce noise. The relation between the Electrode Tip displacement/velocity curve parameters and weld strength was investigated. Among maximum displacement, indentation depth, maximal velocity in cooling phase and maximal velocity in heating phase the latter turned out to be the best parameter for weld strength estimation.

  • Resistance spot weld strength estimation based on Electrode Tip displacement/velocity curve obtained by image processing
    Science and Technology of Welding and Joining, 2014
    Co-Authors: Samo Simončič, Primoz Podrzaj
    Abstract:

    This paper presents a machine vision based Electrode Tip displacement measurement. The displacement is obtained by the observation of a certain area (mask) in a sequence of images. Based on the obtained displacement measurement a Tip velocity was calculated as well. For this signal Kalman filtering was used in order to reduce noise. The relation between the Electrode Tip displacement/velocity curve parameters and weld strength was investigated. Among maximum displacement, indentation depth, maximal velocity in cooling phase and maximal velocity in heating phase the latter turned out to be the best parameter for weld strength estimation.

  • Temperature measurement during resistance spot welding using a digital camera
    2013 IEEE International Conference on Mechatronics and Automation, 2013
    Co-Authors: Primoz Podrzaj, Samo Simončič
    Abstract:

    In this paper a novel approach for temperature measurement during resistance spot welding is presented. The temperature is calculated using the deformation of the Electrode Tip. The deformation is measured using a digital camera which acquires a sequence of images. These images are then compared and analyzed using a digital correlation algorithm. The result is the deformation variation over time, which is then converted to temperature versus time. For a comparison a thermocouple was mounted on the same spot of the Electrode Tip. The comparison of both methods has confirmed the applicability of digital camera for temperature measurement.

  • Image-based Electrode Tip displacement in resistance spot welding
    Measurement Science and Technology, 2012
    Co-Authors: Samo Simončič, Primoz Podrzaj
    Abstract:

    The paper presents a new image processing-based algorithm for Electrode Tip displacement measurement. Its accuracy is evaluated by a comparison with a conventional optical sensor. The results show a clear advantage of the proposed image processing algorithm. A special program was written in order to analyze the algorithm. The Electrode Tips are detected by the program. It also determines the size of the reference areas on the Electrode Tips and tracks these areas during the welding process. Due to a multi-thread implementation of the algorithm the execution time was reduced significantly as compared to previously presented work. Consequently this approach is now applicable for control-related resistance spot welding purposes.

  • 3D Measurement of Electrode Contact Area in Resistance Spot Welding of Coated Steel
    Welding in the World, 2004
    Co-Authors: I. Polajnar, Primoz Podrzaj, D. Bračun, J. Diaci
    Abstract:

    The document discusses the possibility of contact area estimation during resistance spot welding employing post-weld 3D measurement of Electrode indentation. Experimental welding of a common type of mild zinc-coated steel was conducted using two different Electrode Tip types varying welding time, RMS current and number of successive welds. The other parameters (clamping force, voltage, pre- and post-weld time, weld-piece thickness) were constant. The results show that this approach gives valuable information on the conditions under which the weld-spot was formed.

James M Toguri - One of the best experts on this subject based on the ideXlab platform.

  • the effect of the cathode Tip angle on the gas tungsten arc welding arc and weld pool ii the mathematical model for the weld pool
    Journal of Physics D, 1998
    Co-Authors: M Goodarzi, Roland T C Choo, Tomio Takasu, James M Toguri
    Abstract:

    In part I, the effect of the Electrode Tip angle on the arc properties was investigated. In part II, a mathematical model for the weld pool is developed in order to study the effect of the Electrode Tip angle on the weld pool properties. The information required to simulate the flow in the weld pool including the heat flux to the workpiece, the input current density and the gas shear stress, was derived from the arc model. By individually examining the various driving forces in the weld pool, it is found that the buoyancy and electromagnetic forces do not play major roles in determining the flow pattern in the weld pool for a 200 A arc. Instead, the relative magnitude of the gas shear stress and the surface tension and also the sign of the surface tension determine the flow pattern in the weld pool. The Electrode Tip angle which alters the gas shear stress and especially the heat flux to the workpiece can produce a significant change in the overall shape and size of the weld pool. With a very sharp tungsten Electrode, the heat-flux distribution over the weld pool tends to be flatter. In addition, there is a very strong shear stress due to gas flow at the top of the workpiece. The overall result of these two effects is a wider and shallower weld pool.

  • the effect of the cathode Tip angle on the gtaw arc and weld pool i mathematical model of the arc
    Journal of Physics D, 1997
    Co-Authors: M Goodarzi, Roland T C Choo, James M Toguri
    Abstract:

    By developing mathematical models for the arc and the weld pool in the GTAW process, the effect of the Electrode Tip angle on both arc and weld pool was studied. The present paper is concerned with the model for the arc. By applying a variable cathode surface area, the effect of the Electrode Tip angle (in the range of 10 to ) on the arc properties, especially on the anode current density, heat flux and gas shear stress over the weld pool, was investigated. Comparison of the calculated results with the available experimental data for 200 A arcs of different lengths showed that the model predictions for temperatures higher than 10 000 K are in very good agreement. For temperatures less than 10 000 K, some modifications were necessary to take into account the absorption of heat by the cooler parts of the arc. It was found that by increasing the Electrode Tip angle, the anode spot at the weld pool surface tended to be more localized. This led to a higher maximum heat flux and anode current density. On the other hand, the gas shear stress increased on decreasing the Electrode Tip angle.

Samo Simončič - One of the best experts on this subject based on the ideXlab platform.

  • resistance spot weld strength estimation based on Electrode Tip displacement velocity curve obtained by image processing
    Science and Technology of Welding and Joining, 2014
    Co-Authors: Samo Simončič, Primoz Podrzaj
    Abstract:

    This paper presents a machine vision based Electrode Tip displacement measurement. The displacement is obtained by the observation of a certain area (mask) in a sequence of images. Based on the obtained displacement measurement a Tip velocity was calculated as well. For this signal Kalman filtering was used in order to reduce noise. The relation between the Electrode Tip displacement/velocity curve parameters and weld strength was investigated. Among maximum displacement, indentation depth, maximal velocity in cooling phase and maximal velocity in heating phase the latter turned out to be the best parameter for weld strength estimation.

  • Resistance spot weld strength estimation based on Electrode Tip displacement/velocity curve obtained by image processing
    Science and Technology of Welding and Joining, 2014
    Co-Authors: Samo Simončič, Primoz Podrzaj
    Abstract:

    This paper presents a machine vision based Electrode Tip displacement measurement. The displacement is obtained by the observation of a certain area (mask) in a sequence of images. Based on the obtained displacement measurement a Tip velocity was calculated as well. For this signal Kalman filtering was used in order to reduce noise. The relation between the Electrode Tip displacement/velocity curve parameters and weld strength was investigated. Among maximum displacement, indentation depth, maximal velocity in cooling phase and maximal velocity in heating phase the latter turned out to be the best parameter for weld strength estimation.

  • Temperature measurement during resistance spot welding using a digital camera
    2013 IEEE International Conference on Mechatronics and Automation, 2013
    Co-Authors: Primoz Podrzaj, Samo Simončič
    Abstract:

    In this paper a novel approach for temperature measurement during resistance spot welding is presented. The temperature is calculated using the deformation of the Electrode Tip. The deformation is measured using a digital camera which acquires a sequence of images. These images are then compared and analyzed using a digital correlation algorithm. The result is the deformation variation over time, which is then converted to temperature versus time. For a comparison a thermocouple was mounted on the same spot of the Electrode Tip. The comparison of both methods has confirmed the applicability of digital camera for temperature measurement.

  • Image-based Electrode Tip displacement in resistance spot welding
    Measurement Science and Technology, 2012
    Co-Authors: Samo Simončič, Primoz Podrzaj
    Abstract:

    The paper presents a new image processing-based algorithm for Electrode Tip displacement measurement. Its accuracy is evaluated by a comparison with a conventional optical sensor. The results show a clear advantage of the proposed image processing algorithm. A special program was written in order to analyze the algorithm. The Electrode Tips are detected by the program. It also determines the size of the reference areas on the Electrode Tips and tracks these areas during the welding process. Due to a multi-thread implementation of the algorithm the execution time was reduced significantly as compared to previously presented work. Consequently this approach is now applicable for control-related resistance spot welding purposes.

M Goodarzi - One of the best experts on this subject based on the ideXlab platform.

  • the effect of the cathode Tip angle on the gas tungsten arc welding arc and weld pool ii the mathematical model for the weld pool
    Journal of Physics D, 1998
    Co-Authors: M Goodarzi, Roland T C Choo, Tomio Takasu, James M Toguri
    Abstract:

    In part I, the effect of the Electrode Tip angle on the arc properties was investigated. In part II, a mathematical model for the weld pool is developed in order to study the effect of the Electrode Tip angle on the weld pool properties. The information required to simulate the flow in the weld pool including the heat flux to the workpiece, the input current density and the gas shear stress, was derived from the arc model. By individually examining the various driving forces in the weld pool, it is found that the buoyancy and electromagnetic forces do not play major roles in determining the flow pattern in the weld pool for a 200 A arc. Instead, the relative magnitude of the gas shear stress and the surface tension and also the sign of the surface tension determine the flow pattern in the weld pool. The Electrode Tip angle which alters the gas shear stress and especially the heat flux to the workpiece can produce a significant change in the overall shape and size of the weld pool. With a very sharp tungsten Electrode, the heat-flux distribution over the weld pool tends to be flatter. In addition, there is a very strong shear stress due to gas flow at the top of the workpiece. The overall result of these two effects is a wider and shallower weld pool.

  • the effect of the cathode Tip angle on the gtaw arc and weld pool i mathematical model of the arc
    Journal of Physics D, 1997
    Co-Authors: M Goodarzi, Roland T C Choo, James M Toguri
    Abstract:

    By developing mathematical models for the arc and the weld pool in the GTAW process, the effect of the Electrode Tip angle on both arc and weld pool was studied. The present paper is concerned with the model for the arc. By applying a variable cathode surface area, the effect of the Electrode Tip angle (in the range of 10 to ) on the arc properties, especially on the anode current density, heat flux and gas shear stress over the weld pool, was investigated. Comparison of the calculated results with the available experimental data for 200 A arcs of different lengths showed that the model predictions for temperatures higher than 10 000 K are in very good agreement. For temperatures less than 10 000 K, some modifications were necessary to take into account the absorption of heat by the cooler parts of the arc. It was found that by increasing the Electrode Tip angle, the anode spot at the weld pool surface tended to be more localized. This led to a higher maximum heat flux and anode current density. On the other hand, the gas shear stress increased on decreasing the Electrode Tip angle.

Hiroyuki Kokawa - One of the best experts on this subject based on the ideXlab platform.

  • Degradation mechanism of Electrode Tip during resistance spot welding of aluminium alloy sheets
    Science and Technology of Welding and Joining, 2011
    Co-Authors: Masatsune Kondo, Hiroshi Nagata, Akihisa Nishimura, Hiroyuki Kokawa
    Abstract:

    This study investigated the Electrode life and the Electrode degradation characteristics during continuous resistance spot welding of aluminium alloy sheets. When a long welding time and dome radius type Electrode were used, the Electrode life was extended more than that when a short welding time and radius type Electrode are used. The Electrode Tip is considered to degrade by the following mechanism: an Al–Cu alloy layer is formed at the Electrode Tip during continuous welding, and then it peels off from the Electrode Tip transferring to the surface of aluminium alloy sheet. Its peeling makes the Electrode Tip indented and finally the Electrode Tip flattens with increasing diameter of Electrode Tip. In order to eliminate the direct contact between Electrode and worksheet, a special Cu foil insert device for resistance spot welding of aluminium alloy sheets was developed and an extremely long Electrode life was achieved.

  • Degradation Mechanism of Electrode Tip during Resistance Spot Welding of Aluminium Alloy Sheets
    QUARTERLY JOURNAL OF THE JAPAN WELDING SOCIETY, 2010
    Co-Authors: Masatsune Kondo, Hiroshi Nagata, Akihisa Nishimura, Hiroyuki Kokawa
    Abstract:

    This study investigated the Electrode life and the Electrode degradation characteristics during resistance spot welding of aluminium alloy sheets. When a long welding time and the DR type Electrode shape were used, the Electrode life was much longer than that with a short welding time and the R type Electrode shape. The degradation mechanism of Electrode Tip was explained in the following way; firstly, Al-Cu alloy layers were formed at the Electrode top during consecutive welding, and then the layers stuck easily to the surfaces of aluminium alloy sheets so that notable wear took place and the surface profile of Electrode Tip became flat. In order to eliminate the direct contact between the Electrode and the sheet, a special Cu-foil insert device for resistance spot welding of aluminium alloy sheets was developed and achieved an extremely long Electrode life.

  • Degradation mechanism of Electrode Tip during alternate resistance spot welding of zinc coated and uncoated steel sheets
    Science and Technology of Welding and Joining, 2010
    Co-Authors: Masatsune Kondo, Tokujiro Konishi, Nomura Koji, Hiroyuki Kokawa
    Abstract:

    AbstractThe operation life and degradation mechanism of Electrode during resistance spot alternating current welding of zinc coated galvannealed steel sheets were investigated. The Electrode life in alternate resistance spot welding of zinc coated and uncoated steel sheets was extremely short in comparison with welding only on zinc coated steel sheets. During alternate resistance spot welding, the ring shaped nuggets were formed easily. This is attributable to the sticking of the alloy layers formed on the Electrode top during the previous welding of zinc coated steel, to the uncoated steel surface at the following welding, so that notable wear took place, and the surface profile of Electrode Tip became flat. Additionally, an accumulation of highly resistant carbonaceous substance layer at the centre of Electrode top caused an annular flow of welding current to hinder the nugget formation.

  • Degradation Mechanism of Electrode Tip during Resistance Spot Welding of Zinc-Coated Galvannealed Steel Sheets
    QUARTERLY JOURNAL OF THE JAPAN WELDING SOCIETY, 2009
    Co-Authors: Masatsune Kondo, Tokujiro Konishi, Nomura Koji, Hiroyuki Kokawa
    Abstract:

    This study investigated the Electrode life and the Electrode degradation characteristics during resistance spot welding of zinc-coated galvannealed steel sheets. As a result, it was found that the Electrode life in alternate resistance spot welding of galvannealed steel sheets and bare steel sheets was extremely short in comparison with welding of only galvannealed steel sheets. During alternate resistance spot welding, the ring-shape nuggets were formed easily. The reasons for this is explained by the sticking of the alloy layers formed on the Electrode top during previous welding of the galvannealed steel, to the bare steel sheet surface at the following welding of bare steel, so that notable wear took place and the surface profile of Electrode Tip became flat. Additionally an accumulation of highly resistant carbonaceous substance layer at the center of the Electrode top caused an annular flow of the welding current to hinder the nugget formation.