Electric heating – Metal heating – By arc
Patent
1982-07-02
1984-04-03
Shaw, C. C.
Electric heating
Metal heating
By arc
21912403, B23K 912
Patent
active
044410115
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a rotary arc-welding method for carrying out a welding by causing an arc produced from a welding electrode to follow a circular movement.
BACKGROUND OF THE INVENTION
When welding the objects of welding such as thick steel plates by arc welding with a V-shaped or X-shaped groove formed between the objects of welding, the large space in the groove requires a large heat input. This causes such problems as the decrease in toughness of the welding heat affected zone.
To solve the above-mentioned problem, a conceivable method is to form an I-shaped groove, i.e., to form a narrow groove having groove faces facing each other in parallel with a narrow width. By this method, however, it is impossible to cause the arc to reach sufficiently to every corner of the groove to achieve satisfactory penetration into corners and to form a sound welding bead.
As a conventional method to solve the above-mentioned problem, a method is known which comprises carrying out a welding while causing oscillation of the tip of a welding electrode (hereinafter simply referred to as an "electrode") inserted into said narrow groove at a certain frequency in the width direction of the groove.
The above-mentioned welding method is however problematic in: that variation in the bending deformation of the electrode causes variation in the distance between the tip of electrode and the groove, making it impossible to obtain a stable arc; that a complicated oscillation mechanism of electrode is required; that, unless an oscillation width is strictly set up in response to the groove width, an excessive penetration into the objects of welding is caused by the electrode becoming too close to the groove face, and this may cause undercut or contact of the electrode with the groove face, resulting in short circuit of welding electrode; and furthermore, that a defective fusion may be caused at the lap portion of two adjacent beads because of the limited frequency of oscillation of the electrode.
The inventors therefore proposed a rotary arc-welding method, as a welding method which can solve the above-mentioned problems, disclosed in Japanese Patent Provisional Publication No. 133,871/80 dated Oct. 18, 1980 (hereinafter referred to as the "prior art"), which comprises the following steps.
An embodiment of the prior art is described with reference to FIG. 1.
In FIG. 1, 1 and 1' are the objects of welding; 2 is an I-shaped groove; and, 3 is a nozzle inserted vertically into the groove 2. Said nozzle 3 is rotatably fitted to a holder 4 fixed to the leading end of an arm described later around the axis thereof. Also in FIG. 1, 5 is a gear fixed to the top portion of the nozzle 3; 6 is another gear engaging with the gear 5, said gear 6 being rotated by a motor 7 fixed onto said arm; 8 is a tip fixed to the lower surface of the nozzle 3 at a position eccentric from the center axial line of the nozzle 3; 9 is a consumable electrode fed continuously from the end of the tip 8 through the nozzle 3 and the tip 8 toward the groove 2 by a feed roller 10; 11 are rails laid in parallel with the weld line on one of the objects of welding 1'; 12 is a carriage travelling on the rails 11 by means of wheels (not shown); 13 is a vertical screw stock fitted vertically to the carriage 12 through a fitting member 14; 15 is a motor, fixed to the top portion of the fitting member 14, for rotating the screw stock 13; and, 16 is an arm with one end screw-connected with the screw stock 13 and the other end fixed to a side wall of the holder 4.
A welding electric power source (not shown) is connected between said objects of welding 1 and 1' and said electrode 9. Welding current may be supplied to the electrode 9 either through the feed roller 10 or through the nozzle 3.
Another nozzle (not shown) for blowing an inert gas is provided near the tip portion of the nozzle 3 to permit ejection of the inert gas toward the weld zone during welding. When a bore for blowing inert gas is provided at the tip of said nozzle 3, it is not
REFERENCES:
patent: 4249061 (1981-02-01), Puschner
patent: 4316075 (1982-02-01), Isoya et al.
patent: 4328416 (1982-05-01), Dudley et al.
patent: 4350868 (1982-09-01), Takagi et al.
Nomura Hirokazu
Sugitani Yuji
Nippon Kokan Kabushiki Kaisha
Shaw C. C.
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