JPS63144875A - Method for welding galvanized steel sheet - Google Patents

Abstract

PURPOSE:To obtain an excellent weld zone by inclining a steel sheet to be welded with a specified angle and also providing a specified push angle to a welding torch to perform the upward welding and releasing upward Zn gas being generated on the welding. CONSTITUTION:The galvanized steel sheet 10 is inclined with the angle within 5-60 deg. and the upward welding is performed with the push angle of the welding torch 14 as 5-45 deg.. Zn vapor which is generated by being heated at the time of welding is made liable to be released upward along the inclined surface of the steel sheet and the welding is performed with the prescribed push angle, so the Zn vapor is further liable to be released and the excellent welded surface can be obtained in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for arc welding a zinc-coated steel sheet whose surface has been subjected to galvanization, zinc-based coating, or the like.

(Prior art and problems to be solved by the invention) When arc welding this type of zinc-coated steel sheet, since the temperature of zinc is lower than the temperature of the welding atmosphere, zinc rises up as metal vapor during welding. This has caused problems such as a large amount of spatter and an extremely large number of blowholes in the welded portion.

In order to prevent this, prior to arc welding such a zinc-coated steel sheet, pretreatment is performed such as mechanically scraping and removing the zinc coating layer on the surface of the steel sheet, or removing it by burning it with a gas flame, etc. However, it is troublesome to perform such pretreatment prior to # contact, and it also causes a decrease in production efficiency.

(Means for Solving the Problems) The inventor has repeatedly conducted various studies and experiments on means for preventing the occurrence of blowholes, spatter, etc. without performing such pretreatment, and has devised a welding method. The inventors have discovered that this problem can be solved by doing so, and have completed the present invention. The gist is that zinc-coated steel sheets should be
The purpose is to perform upward welding with the welding torch tilted at an angle of 0' or less and with a receding angle of 5° or more and 45° or less.

(Function) It has been confirmed that when zinc-coated steel sheets are arc welded according to the present invention, the occurrence of blowholes and spatter is significantly reduced.

By the way, each condition in the present invention has been established based on various experiments, and the specific principle of its operation is not necessarily clear at present, but the inventor believes that it is due to the following reasons. I'm guessing. In other words, when using conventional welding methods, the vaporized zinc vapor is covered by the molten metal and cannot escape smoothly, resulting in it being trapped in the welding area as bubbles, or causing multiple spatters when it flies up to the surrounding area. In contrast, according to the present invention, the zinc-coated steel sheets to be welded are inclined at a predetermined angle, and the welding work is performed sequentially from the bottom to the top. The zinc tends to escape upward along the inclined surface of the steel plate, and since the welding work is performed at a predetermined receding angle, the molten metal above is pushed downward by the arc pressure at that time, and this causes the zinc to escape upward. It is thought that this makes it easier for the steam to escape upwards, thereby suppressing phenomena such as the zinc steam getting stuck in or the molten metal splashing away and escaping.

In addition, in the present invention, the #i14 angle (royal angle) of the zinc-coated steel sheet is set to 5° to 60° because if this angle of inclination is smaller than 5°, the effect of tilting the steel sheet will be weak, and 60°
If it is larger than °, it becomes difficult to weld, the bead shape deteriorates, and spatter increases.

The reason why the sweepback angle is set to 5'' to 45 degrees is for the same reason.The preferred angle range for these upward advance and sweepback angles is 10' to 45'' for the former and 10' to 30'' for the latter.
is within the range of

(Example) Next, in order to clarify the present invention more clearly, examples thereof will be described below.

As shown in FIG. 1, with the galvanized steel sheet 10 serving as the material being tilted at various angles, upward welding (upward temporary welding) is performed under the following conditions while tilting the welding torch 12 at various angles. Blowpole.

We investigated the occurrence of spatter, etc. The results are shown in Table 1 in comparison with the welding method.

In FIG. 1, the angle α on the right side from the perpendicular line 14 to the steel plate 1o is the angle β in the opposite direction of the receding angle 1, or the advancing angle.

° [Welding conditions] Base material 2.8 ta-thick double-sided alloyed galvanized steel plate Joint shape Lap fillet welding (gaffe 0.1 mm) Welding length 250mm Wire diameter 1.2φ Welding current 180A Table 1 A pit is a hole in which a blowball penetrates to the surface of a welded part, and this blowhole was investigated using a radiographic test.

As can be seen from the table, when welding is performed with the galvanized steel sheet 1o horizontal, when the welding torch 12 is tilted back and forth with the galvanized steel sheet 10 horizontal, when the galvanized steel sheet 10 is tilted When the welding torch 12 is advanced in the downward direction, and even when the galvanized steel sheet 10 is tilted and welded upward, when the welding torch 12 does not have a receding angle,
That is, if the welding torch 12 is perpendicular to the galvanized steel sheet IO or has an advancing angle, many blowholes and spatters will occur, and pits will appear. When upward welding is performed with the welding torch 12 tilted and set at a certain receding angle, these blowholes and spatter are significantly reduced.
The results also clearly show that no pits occur.

(Effects of the Invention) As detailed above, according to the present invention, upward welding is performed with a zinc-coated steel sheet in an inclined state and at a predetermined receding angle.

According to the present invention, it is possible to successfully weld the steel plate without removing zinc on the surface of the steel plate through pretreatment, thereby eliminating the time and labor required for pretreatment and improving production efficiency. ': 4 Excellent effects are produced.

[Brief explanation of the drawing]

FIG. 1 is a diagram IIJ1 for explaining an embodiment of the welding method according to the present invention. lO: Galvanized steel plate 12: Welding torch

Claims (1)

[Claims] A method for arc welding a zinc-coated steel plate whose surface is coated with zinc, wherein the zinc-coated steel plate is inclined at an angle of 5° to 60°, and the welding torch is tilted at an angle of 5° or more. A method for arc welding zinc-coated steel sheets, characterized by performing upward welding with a receding angle of 45° or less.