Murata Welding Laboratory Co.

Murata, Japan

Murata Welding Laboratory Co.

Murata, Japan
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Kyohei K.,Osaka University | Masaya S.,Osaka University | Manabu T.,Osaka University | Akihisa M.,Murata Welding Laboratory Co. | Tadasuke M.,Murata Welding Laboratory Co.
Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society | Year: 2014

Effects of a constricted nozzle on the arc phenomena in Tungsten Inert Gas (TIG) welding process are investigated by numerical simulation. The obtained results show that the temperature and velocity of the arc plasma are increased by attaching an additional gas nozzle which is called "constricted nozzle". As a result, the iron vapor does not diffused upward but transported outward. In addition, the heat transfer to the base metal surface is enhanced.


Konishi K.,Osaka University | Shigeta M.,Osaka University | Tanaka M.,Osaka University | Murata A.,Murata Welding Laboratory Co. | And 2 more authors.
Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society | Year: 2015

GTA (Gas Tungsten Arc) welding has been used in manufacturing field and studied as a higher level welding process. To understand the arc phenomena that are complicated, it is significant to measure the temperature distribution of arc. Although Fowler-Milne method is one of the popular measurement methods, it is applied only under the assumption of LTE (Local Thermodynamic Equilibrium). In this study, the reliability of Fowler-Milne method is investigated by comparison of results between Fowler-Milne method and numerical simulation for six shielding gas conditions (Ar, He, N2, Ar+50%He, Ar+20%N2 and Ar+5%H2). The area in which the agreement between both ways is more than 95% is considered as that in which the LTE assumption is valid. The validity of this evaluation is discussed from the viewpoint of the collision frequency of species in the arc. The present study shows that LTE is valid for the area with the collision frequency of 2.0 × 1034 m-3s-1 for pure Ar arc, and the area with the collision frequency of more than 1.0 × 1035 m-3s-1 for other four conditions (N2, Ar+50%He, Ar+20%N2 and Ar+5%H2). However, for pure He arc, the collision frequency is much lower than the other conditions. Therefore, He arc is not in LTE for the whole area, which suggests that another method is required to measure the accurate temperature distribution for pure He arc.


Konishi K.,Osaka University | Shigeta M.,Osaka University | Tanaka M.,Osaka University | Murata A.,Murata Welding Laboratory Co. | Murata T.,Murata Welding Laboratory Co.
Yosetsu Gakkai Ronbunshu/Quarterly Journal of the Japan Welding Society | Year: 2014

We investigate how welding conditions affect the arc in TIG welding with a constricted nozzle by numerical simulation using an axial-symmetric two-dimensional model. When helium is used as a shielding gas, the effect of the constricted nozzle is more remarkable than argon. The heat flux to the center of the anode surface increases more with a higher welding current. This feature is suitable for pulsed welding. Even if an electrode is consumed and its tip angle is changed, a stable arc plasma and heat intensity are obtained. © 2014, Japan Welding Society. All rights reserved.


Kyohei K.,Osaka University | Masaya S.,Osaka University | Manabu T.,Osaka University | Akihisa M.,Murata Welding Laboratory Co. | Tadasuke M.,Murata Welding Laboratory Co.
Welding International | Year: 2016

Effects of a constricted nozzle on the arc phenomena in the tungsten inert gas (TIG) welding process are investigated by numerical simulation. the obtained results show that the temperature and velocity of the arc plasma are increased by attaching an additional gas nozzle, which is called the "constricted nozzle". As a result, the iron vapour does not diffuse upward but is transported outward. In addition, the heat transfer to the base metal surface is enhanced. © 2016 Taylor & Francis

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