Hitachi Construction Machinery Co., Ltd.

Hikaru Yamamoto

Yutaka Takano

Toru Takatani

Shigeyuki Sakurai

Naoki Miyanagi

Toru Nakajima

Katsunori Wada

Yoshiaki Shimomura

Toyoyuki Sato

Yasuo Hayakawa

Shuhei Kanemaru

Kazumichi Hosoya

Manabu Hirakawa

Provided is a plasma arc welding method for continuously welding a welding target part of a welding workpiece while forming a keyhole weld on the welding target part of the welding workpiece using a plasma arc. A pulse current is used for a welding current, and the pulse frequency of the pulse current is controlled so as to be a frequency that is synchronized with a weld pool (P) during the welding. With this approach, vibration of the weld pool during keyhole welding can be controlled so as to synchronize with the pulse frequency of the pulse current. As a result, when the plasma arc keyhole welding is performed, a stable penetration bead having a desired height can be reliably obtained without hanging or irregularity.

Plasma arc welding method and plasma arc welding device

In a plate assembling step, a gap () is formed between a leading end portion (A) of a groove () provided on an upright plate () and a lower plate (). An arc is generated from a welding wire () toward a back surface (C) side of the groove () through the gap (), to form a satisfactory penetration bead () on the back surface (C) side of the groove (). Next, the welding wire (), the lower plate (), the groove () of the upright plate () and the penetration bead () are fused to form a first-layer welding bead (), thereby firmly joining the lower plate () and the groove () of the upright plate (). The first and second welding steps are performed continuously after performing the plate assembling step, to enhance workability at the time of welding the lower plate () and the upright plate ().

Welding method for T-joint

A welding method is disclosed for butt welding a first base materialand a second base materialwith each other. To also permit stable and efficient formation of a bead in the form of a fillet weld on a back side of a groove by conducting arc welding from the side of the groove without arranging a bead beforehand on the back side of the groove, the first memberon which a root faceand a single groove facehave been formed, is brought at its root faceinto contact with a flat surfaceof the second base materialA welding wireis arranged facing on the groove formed by the contact between the first base materialand the second base materialThe first base materialand the second materialare caused to fuse at an area of contact between them by an arc from the welding wireA melt, which has been formed by the fusion at the area of contact and the like, is forced out to the back side of the groove to form a bead Bin the form of a fillet weld on the back side of the groove.

Welding method, welding device, welded joint, and welded structure

In an arc welding method and apparatus, a plasma ( ) is generated at a welding intended position on a base material ( ) by a laser ( ) irradiated to the base material ( ). When a discharge electrode ( ) is at a minus potential, an arc discharge ( ) takes place in the direction of the plasma ( ) and is induced at a position irradiated with the laser ( ). When the electrode ( ) is at a plus potential, arc electrons are generated from a laser irradiated point and discharged to the electrode ( ). When a voltage applied between the electrode ( ) and the base material ( ) is alternating, the polarities of the electrode ( ) and the base material ( ) alternately change so that the foregoing phenomena alternately occur. When the base material ( ) is at a minus potential, an arc discharge ( ) takes place from a laser spot. Also, in regard to the arc discharge ( ), since the plasma ( ) is generated by the laser ( ), a stable arc discharge ( ) can be generated irrespective of the state of the base material ( ) or the state of the electrode ( ).

Method for guiding arc by laser, and arc guiding welding and device by the method

A narrow gap welding method by which V-shaped or single-bevel grooved multi-layer build-up welding is carried out, comprises the steps of welding a first layer by applying a welding current by which a globule transfer pattern is made into a spray pattern by a waveform in which a direct current and a pulse current are caused to overlap, and thereafter welding the second layer by applying a direct current.

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Tsuchiura, Japan

Hikaru Yamamoto