JPH017996Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention solves the insufficient heating of the central part of the plate thickness in the high-frequency resistance method during welding of thick-walled steel pipes, and in order to obtain good welding quality, on the upstream side of the heating by the high-frequency resistance method, This invention relates to a multi-electrode TIG heating device that heats the central part of the thickness of opposing steel strips.

If the steel strip becomes thick, the central part of the plate thickness will be insufficiently heated using only the high-frequency resistance method, resulting in welding defects (poor welding in the central part of the plate thickness) after electric resistance welding. As a measure to eliminate welding defects, after the steel strip is roll-formed and before it is heated using a high-frequency resistance method, the central part of the plate thickness is preheated. The gap will be narrow.

Until now, no device has been found that heats the central part of the thickness of the steel strip on both sides of the opposing steel strip at such a spacing.Although a TIG torch may be used as a heating method, it is possible to use a TIG torch inserted within a 15 mm spacing and horizontally with an arc. Devices that generate arcs have problems with stability during arc generation, stability of arc generation points, arc deflection measures, long life of electrodes, etc., and have not been put into practical use.

The device of this invention simultaneously heats the central part of the thickness of the left and right steel strips (with a spacing of about 15 mm).
This is a device with a large number of electrodes arranged on the left and right sides, and its gist is that it is a multi-electrode TIG heating device that heats the steel strip before it is roll-formed and then subjected to electric resistance welding. A chip is provided, a circular hood is provided around the tungsten chip, an Ar gas injection hole is provided at a position inside the installation position of the hood, and an Ar gas supply passage and a cooling water passage are connected to the Ar gas injection hole. This multi-electrode TIG heating device includes an electrode body containing a built-in electrode, and is connected to a transformer via a cooling cable.

Next, the multi-electrode TIG heating device of the present invention will be explained in detail using FIGS. 1 to 4.

Figure 1 is an overall view of the device of the present invention.
When performing electric resistance welding, usually high frequency resistance welding equipment 2 is used.
However, when manufacturing thick-walled steel pipes, the concept of preheating (heating) the base material before performing electric resistance welding has recently been clarified, and the present invention is based on this idea. A heating device 3 is provided.

The multi-electrode TIG heating device 3 has an electrode main body 4, a transformer 5, a TIG heating earth block 6, etc. connected via a cooling cable 7, etc. Electrode body 4
The details of this are shown in FIGS. 2 to 4, and the electrode body 4 is roll-formed and inserted into an opening 8 of about 15 mm before being formed into a steel pipe, and the electrode body 4 is inserted into the opening 8 of about 15 mm to form the steel pipe 1. The thick central part is heated.

Further, the TIG heating device 3 needs to ensure arc startability and arc straightness as heating conditions, and the present invention takes these points into consideration. In other words, arc startability is significantly affected by the electrode structure, and the present invention
As shown in the example of heating using Ar gas, the arc start will not be stable unless the Ar gas purity at the tungsten loss part is maintained at a high purity, which is why the circular hood 9 is provided. .

However, if the circular hood 9 is simply provided, air entrainment will occur and the tungsten end will be damaged.
Unable to maintain high Ar gas purity. Therefore, the circular hood 9 is a butt-full type hood. Furthermore, in order to ensure the straightness of the arc described above, it is sufficient to prevent the drift of the Ar gas, and for this purpose, the buff-full type hood 9 is used.

This buff-full type circular hood 9 will be explained in detail with reference to the drawings. The hood 9 is attached to the electrode body 4
The installation position overlaps with the Ar gas ejection port 12 of the Ar gas supply passage 11 provided therein.

That is, to explain with FIG. 3, the Ar gas outlet 12
As shown in the figure, the hoods 9 are provided so as to overlap at a portion a, so that Ar gas is ejected from the Ar gas outlet, collides with the hood 9 at point a, and proceeds in the direction shown by the arrow. By providing such a hood 9, it is possible to prevent air drift and to create an Ar gas atmosphere around the tip of the tungsten chip, thereby making it possible to prevent the arc from flowing straight. It is extremely advantageous.

The material of the hood 9 is required to have sufficient heat resistance, good electrical insulation, and easy molding, and boron nitride (BN) is advantageous in order to satisfy these requirements. It is something.

Further, since the temperature of the electrode body 4 rises due to continuous long-time arc generation, cooling water is passed through the electrode body 4, and a cooling water passage 13 is provided for this purpose.

As described above, the present invention provides a multi-electrode TIG heating device that is advantageous in terms of stability during arc generation, stability of the arc generation point, countermeasures against arc deflection, etc., and its effects are extremely large. .

[Brief explanation of the drawing]

Fig. 1 is an overall explanatory diagram of the device of the present invention, Fig. 2 is a partial explanatory diagram of the electrode body used in the device of the present invention, Fig. 3 is a view taken along arrow A-A' in Fig. 4, and Fig. 4 is the electrode main body. FIG. 4... Electrode body, 9... Hood, 10... Tungsten chip, 11... Ar gas supply passage, 1
2...Ar gas outlet, 13...Cooling water passage.

Claims (1)

[Scope of utility model registration request] In a multi-electrode TIG heating device that roll-forms a steel strip and then heats the steel strip before electric resistance welding, the electrode body is provided with a tungsten tip, a circular hood is provided around the tungsten tip, and the hood is heated. An Ar gas nozzle is provided at a position inside the installation position, an electrode body is provided with a built-in Ar gas supply passage and a cooling water passage connected to the Ar gas nozzle, and the electrode body is connected to the transformer via a cooling cable. Multi-electrode TIG heating device.