Babcock-hitachi Kabushiki Kaisha

Hitachi, Ltd.

Katsuyoshi Hori

Toshiaki Takuwa

Toshiharu Myoga

Kazuki Kusano

Eiji Watanabe

Osamu Yamada

Shigeyoshi Kawano

Toshiharu Nagashima

Atsuya Kamada

Mitsuhiro Takasaki

Hiroya Murakami

Nobuwo Nakazawa

Yosiaki Matsumura

Masahiko Sadakane

Takeshi Kagawa

Yoshiaki Matsumura

Miharu Shinomiya

Yukio Hosono

Miharu Hafuri

Tetsuji Terada

Yasuhiro Butsusaki

Yuji Futami

An excellent welding tip in the feed stability of a wire, in the release capacity of foreign matter, and in the stability of current control, and a process for manufacturing such a tip economically, is achieved in accordance with a sectional shape of a guide hole opened and provided to a welding tip. The sectional shape is derived by forming a wire in a passable non-circular shape. The sectional shape of the guide hole may be a polygonal or elliptic shape, or approximately so. In the case of making the sectional shape of the guide hole polygonal, it is more preferable to make it a polygon circumscribing on a circle, for example, such a polygon circumscribing on a larger circle than the outer diameter of the wire to be inserted into the guide hole by 0.02-0.20 mm in diameter. Specifically, it is preferable to arrange the sectional shape as a triangle.

Tips for welding and their manufacturing process

An unconsumable electrode such as tungsten is opposingly arranged with a base metal to be welded. An AC arc welding power supply is connected between the base metal and the unconsumable electrode. A filler wire such as of aluminum is fed by a wire feeder toward an arc-generated part between the base metal and the unconsumable electrode. Also included is a wire-heating power supply for producing a pulsed current. The wire heating power supply heats the filler wire by supplying thereto a pulsed current in accordance with a sync signal from the AC arc welding power supply or a detection signal of an arc current i.sub.A or an arc voltage of the AC arc power supply. The filler wire is thus heated by being supplied with a heating current i.sub.W in pulse form while the unconsumable electrode is kept negative by an AC arc formed between the unconsumable electrode and the base metal. During the period when the unconsumable electrode is kept positive by the AC arc, the filler wire is not supplied with any current or is heated by being supplied only with a sufficiently small current not to cause any substantial magnetic flow. Accordingly, even if a large current flows through the wire, arc interruptions can be eliminated, thereby improving the welding process of aluminum by using an AC TIG arc.

AC TIG welding apparatus using hot wire

A semi-automatic hot wier TIG (Tungsten Inert Gas) welding equipment comprising: a portable TIG arc torch; a portable filler wire feed torch; a hot wire switching power source for energizing the TIG arc torch, the filler wire feed torch and a base metal; a filler wire feeding device for feeding the wire to the wire feeding torch at a desired rate; a welding condition control device for controlling wire heating power so as to provide wire heating power commensurate to the wire feed rate; means for measuring the resistance value of the wire extension section between the terminal end of the wire and the terminal end of the filler wire feed torch; and means for controlling said filler wire feeding means to change the wire feed rate in response to the detected wire extension. According to the present invention, the welding operations are performed while the filler wire feed torch is held in one hand and the TIG arc torch is held in the other hand, so that the position where the arc and wire are inserted can be desireably adjusted. Adjustment of the welding conditions such as regulation of the welding arc current and adjustment of wire feed rate can be readily performed during welding.

Semi-automatic hot wire tig welding equipment

A method and an apparatus for controlling the hot-wire welding process is disclosed in which the heating power for a hot-wire is automatically regulated to a proper value. The wire-heating power after fusing of a filler wire by being overheated is set to a level lower than the heating power immediately before wire fusing, and the wire-heating power is again increased gradually from the set value until the wire is fused by being overheated. By repeating this process, the molten state of the filler wire in the hot-wire TIG welding is automatically kept in optimum condition without requiring any operation of the welding operator or his intuition. Further, during the energization of the filler wire, the instant of fusing by overheating of the wire is detected, and the detected signal is used to sharply reduce or suspend the wire current immediately, whereby spatters which otherwise might be caused by fusing of the overheated wire is prevented or greatly reduced, and the adhesion of the spatters to the arc electrode is prevented, thereby permitting a hot-wire welding operation continuously over a long time. Furthermore, a pulsed current is used for heating the filler wire, and the wire terminal voltage during de-energization of the wire is detected, thereby detecting whether the wire is in contact with a base metal. If the wire is not in contact with the base metal, a current is not supplied during the next pulse application period, so that the current is prevented from flowing from a tungsten electrode to the wire while the wire is not in contact with the base metal.

Method of control and apparatus for hot-wire welding

A hot wire TIG welding apparatus has a current detector for detecting the peak period and base period of the arc current. The welding apparatus further has a controller which controls, in response to the detection signal from the current detector, the operation of the wire heating power supply such that the wire heating power is supplied only during the base period of the arc current. According to this arrangement, a hot wire switching TIG welding apparatus can be produced using commercially available power supply systems for TIG arc welders, without requiring substantial change or modification of the control circuits in the TIG arc welders.

Hot-wire TIG welding apparatus

A hot-wire TIG welding apparatus capable of performing a stable welding regardless of change in the welding conditions. The welding apparatus comprises a hot-wire feed speed control means for controlling the speed of feed of a hot wire, and a heating power control means adapted to control the electric power for heating the hot wire. The condition of the control in either one of the control sections is changed in accordance with a change in the control condition of the other.

A method of and an apparatus for fabricating a spiral fin in which a strip of material is bent with rolling by a pair of rolls while being imparted with a tension to reduce the speed at which the strip is drawn between the pair of rolls to reduce a compressive force applied to a portion of the strip corresponding to an outer edge portion of the spiral fin, thereby improving the forming limit of the spiral fin.

Method of and apparatus for fabrication of spiral fin

Growing community of inventors

Kure, Japan

Katsuyoshi Hori