JP2010284691A - Narrow gap welding method of thick steel plate and thick steel tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a welding technology capable of executing the narrow groove welding of a thick-wall steel plate or steel tube without need of any machining by using a conventional gas cutting or plasma cutting in the beveling. <P>SOLUTION: A method for executing the narrow groove welding of two steel plates or a steel tube as a workpiece to be welded includes: a step of executing the beveling by the gas cutting or the plasma cutting; a step of constituting a joint part by executing the temporary welding of a rectangular insert held by a joint part; a step of coating a deep penetration active material on an inner surface of a groove of the rectangular insert in the groove; and a step of executing the arc welding of the joint part. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a welding method performed by applying a deep penetration activator. Furthermore, it is a welding method related to narrow groove welding in which the plate thickness is large and the groove is narrowed.

  Narrow bevel technology is widely used because narrow gaps (narrow gaps and narrow bevels) can be used for the welding of thick steel plates and steel pipes. The dimension is one of the important factors affecting the welding result.

  And when performing narrow groove welding conventionally, as shown in FIG. 3 (1), (2), it is necessary to process a groove root part into circular or a rectangle. This processing requires machining with a tool or the like. At this time, if the construction is a small steel plate or steel pipe, machining is possible, but if the plate thickness is large or the steel plate size is large, for example, in the case of a cylindrical pressure vessel used in a plant, its diameter May be as long as 6 m, and in such a case, machining becomes difficult in the groove processing. Even if possible, considering the preparation period and machining time of the groove machining, a long time and enormous cost are required, so the merit of narrow groove welding is greatly impaired.

  Further, as a groove processing means, there is a gas cutting. However, since the gas cutting can be performed only by a straight line, a narrow groove processing cannot be performed. Further, if the steel plate is cut by gas cutting, the end face becomes a straight line, and if the two steel plates are joined, the joint becomes V-shaped and the back wave welding cannot be performed. Moreover, it is difficult to weld even if a gap is formed.

  On the other hand, with regard to welding technology, deep penetration activators (flux) that can achieve deeper penetration have been developed, and narrow groove welding equipment that can efficiently perform narrow groove welding has been developed. (For example, refer to Patent Document 1).

Utility Model Registration No. 3139345

  Therefore, an object of the present invention is to provide a welding technique that uses conventional gas cutting or plasma cutting for groove processing, does not require machining, and enables narrow groove welding work even on thick steel plates and steel pipes. To do.

In order to achieve the above object, the reverse wave welding method of the present invention includes a step of performing groove processing by gas cutting or plasma cutting in narrow groove welding of two steel plates or steel pipes to be welded, and a joint portion. It consists of a step of sandwiching a rectangular insert and performing a tack welding to form a joint portion, a step of applying a deep penetration activator to the inner surface of the rectangular insert groove in the groove, and a step of arc welding the joint portion.
Further, it is preferable to protect the back surface molten metal with a backing material or an inert gas in order to prevent oxidation of the back surface molten metal and prevent the molten metal from falling.

Furthermore, in order to achieve the above-mentioned object, the welding method of the present invention is a gas cutting method in the case of performing narrow groove welding by performing both-side groove processing of butt welding of two steel plates or cylindrical containers that are workpieces. Alternatively, the process of groove processing by plasma cutting, the process of forming a joint part by sandwiching a rectangular insert in the center and performing temporary welding, and applying the deep penetration activator to the inner surface of the rectangular insert groove in the groove And a step of arc welding the surface of the joint portion, a step of applying a deep penetration activator from the back side to the inner back surface of the groove of the rectangular insert, and a step of arc welding the rear surface of the joint portion.
Further, it is preferable that the melt-bonded portion formed from the front surface side and the melt-bonded portion formed from the back surface side overlap each other at the center portion of the plate thickness.

  Further, it is preferable that the arc welding in the two welding methods is performed by TIG welding by a TIG welding apparatus that periodically controls the parallel weaving motion in addition to the arc weaving welding method by rotating the eccentric electrode.

  In the two welding methods, the target steel material to be welded is preferably stainless steel or low carbon steel, and the groove angle is preferably 2 ° to 10 °.

As described above, the present invention uses conventional gas cutting or plasma cutting for groove processing and does not require machining. When the steel sheet is cut by gas cutting, the end face becomes a straight line, but a rectangular insert is sandwiched between them to form a joint by temporary welding, a deep penetration activator is applied, and arc welding, preferably TIG welding is performed. Is. The deep penetration activator is used because a sufficient thickness is required for the rectangular insert for the narrow groove welding of thick steel plates and steel pipes as in the present application.
This makes it possible to perform welding extremely efficiently without requiring machining for the groove processing.

  The deep penetration activator used here may be any commercially available deep penetration activator as long as the quality is high and a deep penetration can be obtained. Currently, deep penetration activators capable of penetration welding of about 8 mm are on the market, and even if such activators capable of penetration of 8 mm or more can be used, the purpose of this application can be achieved. Uses a commercially available deep penetration activator (trade name: PATIG-SA), penetration welding up to a maximum of 12 mm is possible, and the object of the present application can be achieved most efficiently. A comparison between manual TIG welding using a conventional penetration activator and automatic welding using a deep penetration activator (trade name: PATIG-SA) is shown below.

  Further, as a welding method after applying the deep penetration activator, arc welding such as TIG welding is performed by using various commercially available narrow groove welding apparatuses. However, it takes a lot of labor and time to insert a rectangular insert into a thick plate and weld it appropriately.

  Therefore, a TIG welding apparatus that periodically controls parallel weaving motion in addition to the arc weaving welding method by rotating the eccentric electrode, particularly arc weaving by rotating the eccentric electrode shown in Utility Model Registration No. 3139345, developed by the applicant. In addition to the welding method, it is most preferable to use a TIG welding apparatus (hereinafter referred to as a composite weaving apparatus) that periodically controls parallel weaving motion. Thereby, welding can be performed at an appropriate location in an extremely short time, and the effect of the method of the present application can be maximized.

  The narrow groove TIG welding apparatus shown in the utility model registration No. 3139345 is (1) an electrode that rotates within the narrow groove to melt the wire, and the electrode has an angle of 30 ° to 45 °. (2) having two wires fed from the front and rear of the eccentric electrode on the basis of the welding direction, (3) In the two wires, the wire fed from the front of the eccentric electrode is heated, and the wire fed from the rear is a wire fed without heating. (4) Of the two wires, both the wire fed from the front of the eccentric electrode and the wire fed from the back are heated and fed. (5) Also, the narrow gap Depending on the combination of electrode width and eccentric electrode diameter The rotation angle of the eccentric electrode is ± 45 ° to ± 90 ° with reference to the position where the electrode tip is oriented at the groove center. (6) Also, the eccentric electrode is rotated left and right. The current that flows simultaneously with stopping at both ends of the metal side wall is different from the current that flows when moving in the direction opposite to the welding progress direction. (7) Furthermore, the eccentric electrode is held. The TIG torch has a conical nozzle whose concentric inner diameter is +1.0 to 1.8 mm larger than the eccentric outer electrode diameter, and the outer diameter angle is 18 ° to 22 °. Welding having one gas nozzle, having a TIG torch tip shape with an inside cone angle of 12 ° to 16 °, and having the corresponding gaps for flowing an inert gas having a different flow rate in each gap Device.

When the above composite weaving device is used, it is possible to achieve ultra-thickness by using the composite weaving rotary eccentric electrode narrow gap welding method while synchronizing the parallel weaving and the rotary weaving using the fact that there are two oscillation controls. Narrow gap welding can be easily solved.
That is, from the root part reverse wave welding to the plate thickness of 70 mm, the eccentric electrode is rotated and welding is performed, and when the plate thickness is 70 mm or more, the eccentric electrode weaving and the parallel weaving are synchronized to perform welding by composite weaving. .
That is, the torch main body performs parallel weaving at the center portion of the groove, and when the both ends are stopped, the eccentric electrode can generate an arc on the side wall to ensure sufficient melting. (As shown in Fig. 4 (2).)
Each parameter waveform in this case is shown in FIG. The weaving locus is as shown in FIG. Even in this composite weaving rotation eccentric electrode narrow gap welding, the center gas and the shield gas are located at 43 mm and 71 mm from the tip of the electrode, so that a sufficient shielding effect is exhibited.

  In this way, TIG welding using a composite weaving device makes it possible to properly direct the arc to the thick plate on both sides and the rectangular insert joint, so welding can be performed easily in a very short time. In addition, backside welding can be performed by the effect of the activator.

  Further, if the thickness of the rectangular insert is increased, it must be supported by a backing material. For stainless steel, a sound weld metal can be secured by preventing oxidation with an inert gas (argon).

  When the plate thickness is further increased and both side grooves are adopted, a rectangular insert is sandwiched at the center of the plate thickness, and temporary welding is performed. In this case, it is possible to use the ability to ensure overlapping penetration by welding from both sides using the ability of deep penetration activator without reverse wave welding, so the thickness of the rectangular insert is increased to a maximum of 18 mm. I can do it.

The welding conditions such as the welding current, voltage, and welding speed differ depending on the plate thickness, material, deep penetration activator used, and welding machine, and may be set as appropriate according to each condition.
As an example of specific welding conditions of the present invention, a test record (welding conditions) of one side, that is, a groove welding inner surface, is shown in the following table as an example. In addition, the steel plate thickness is 19 mm, the rectangular insert is 9 mm (width) X 3 mm (thickness), the deep penetration activator described in Japanese Patent Application No. 2008-232932 (PATIG-SA), and welding is performed using a composite weaving device.

In this way, the rectangular insert can be welded in one pass, and the efficiency of narrow groove welding of thick steel plates and steel pipes has been dramatically improved.
In addition, also when welding from both sides of a rectangular insert, it can carry out on the welding conditions similar to the said table | surface.

  Conventional gas cutting or plasma cutting is used for groove processing, and machining is not required, and narrow groove welding can be performed even on thick steel plates and steel pipes.

FIGS. 1 (1) to (4) are diagrams illustrating a backside welding method according to the present invention, and FIG. 1 (1) is a diagram illustrating a state in which a rectangular insert is sandwiched between steel plates and tack welded. FIG. 1 (2) is a view showing a state in which a deep-penetration activator is applied to the inner surface of the groove of the rectangular insert, and FIG. 1 (3) is a TIG welding process using a composite weaving device. FIG. 1 (4) shows a state in which the back wave welding is completed. 2 (1) to 2 (5) are diagrams showing welding on the front side and the back side, that is, both sides, and FIG. 2 (1) shows a temporary welding in which a rectangular insert is sandwiched between the center portions between steel plates. 2 (2) is a view showing a state in which a deep-penetrating active agent is applied to the groove inner surface of the rectangular insert, and FIG. 2 (3) is a rectangular shape. It is a figure which shows the state by which welding was performed to the groove inner surface (joint part surface) of an insert, and FIG.2 (4) is the state by which the deep penetration active agent is apply | coated to the groove inner back surface of a rectangular insert. FIG. 2 (5) is a diagram showing a state in which welding is performed on the back surface in the groove (back surface of the joint portion) of the rectangular insert. 3 (1) and 3 (2) are diagrams showing a conventional narrow groove shape, FIG. 3 (1) is a diagram showing a U-shaped groove, and FIG. 3 (2) is an H-shaped groove. It is a figure which shows a tip. 4 (1) and 4 (2) are diagrams showing a welding method for ensuring arc-free welding by generating an arc directly on the narrow gap side wall by rotating the eccentric electrode, and FIG. It is a figure which shows the case where thickness is 25 mm-80 mm, and FIG. 4 (2) is a figure which shows the case where plate | board thickness is 80 mm-300 mm. It is a figure which shows the waveform of each parameter. It is a figure which shows the locus | trajectory of weaving.

  An example of an embodiment of the present invention will be described with reference to the drawings.

1 (1) to 1 (4) are diagrams showing the back wave welding method of the present invention. As shown in FIG. 1, the workpieces 1 and 2 are grooved on a straight line by gas cutting or plasma cutting.
In FIG. 1 (1), the groove angle is 4 ° to 10 °, and the rectangular insert 3 having a width of 6 to 10 mm and a thickness of 2 to 6 mm is sandwiched between the steel plates and does not come off. In this manner, a state in which the joint is formed by the temporary welding 4 from the outside is shown.

  FIG. 1 (2) shows a state in which a deep-melt active agent (flux) 7 is applied to the groove inner surface of the rectangular insert 3. As shown in the figure, the deep-penetration activator 7 needs to be applied to at least the inner surface of the groove of the rectangular insert 3, but is preferably applied to the periphery of the joint with the workpieces 1 and 2. The

  FIG. 1 (3) shows a state in which TIG welding is performed by rotation of the eccentric electrode 5 of the composite weaving device. The upper straight arrow indicates the direction of parallel weaving, and the lower semicircular curved arrow indicates The direction of eccentric electrode rotation weaving is shown.

  FIG. 1 (4) shows a state in which the back wave welding is completed. Moreover, the figure number 6 shows a welding junction (welded part).

2 (1) to (5) are diagrams showing welding (TIG welding) to the front side (front side), the back side (back side), that is, both sides (both sides), and FIG. In the case where the thicknesses of the objects 1 and 2 are thicker than 40 to 250 mm or more, the groove angle is 2 ° to 10 °, the rectangular insert 3 having a width of 6 to 12 mm and a thickness of 6 to 18 mm is formed at the center. The state where it is sandwiched and is tack-welded 4 is shown.
In addition, the to-be-welded objects 1 and 2 are processed linearly from both front and back sides by gas cutting or plasma cutting so that the rectangular insert 3 can be sandwiched between the center portions and narrow groove welding can be performed from both sides.

  FIG. 2 (2) shows a state in which the deep penetration active agent 7 is applied to the groove inner surface (front side) of the rectangular insert 3.

  2 (3) shows the result of TIG welding using the rotation of the eccentric electrode 5 of the composite weaving device as in FIG. 1 (3) (see FIGS. 4, 5 and 6). It is a figure showing that welding on the front side in the groove has been completed.

    FIG. 2 (4) shows a state in which the deep-melt active agent 7 is applied to the inner back surface (back side) of the groove of the rectangular insert 3.

    FIG. 2 (5) is a view showing a state in which TIG welding is performed on the inner surface and the rear surface of the groove of the rectangular insert 3. As shown in the figure, the melt-bonded portion 6 formed from the front surface side and the melt-bonded portion 6 formed from the back surface side are overlapped at the center of the plate thickness.

  3 (1) and 3 (2) are diagrams showing a conventional narrow groove (narrow gap) groove shape, and FIG. 3 (1) shows a thickness of a workpiece to be welded of 40 to 200 mm and a groove angle of 4 °. It is a figure which shows U-shaped groove | channel which is 10 degrees, route radius R4-R10, route surface 14-20,0 mm, gap 0 + 1, 0 mm.

  FIG. 3B is a diagram showing an H-shaped groove having a thickness of 40 to 250 mm, a groove angle of 4 to 10 °, a route radius R4 to R10, and a route surface of 14 to 20 mm. .

  4 (1) and 4 (2) show a welding method in which an arc is directly generated on the narrow gap side walls (workpieces) 1 and 2 by rotating the eccentric electrode 5 so as to ensure welding with no penetration failure.

  FIG. 4A shows a case where the plate thickness is 25 mm to 80 mm, and adopts a narrow gap welding method in which only the electrode is protruded from a double flux (double focusing) torch and the electrode is rotated. The groove angle is 6 to 20 mm, and the eccentric electrode 5 is rotated ± 45 °.

  FIG. 4 (2) shows a case where the plate thickness is 80 mm to 300 mm, the groove angle is 20 mm or more, and the eccentric electrode 5 rotates ± 90 °.

1.2 Workpiece 3 Rectangular insert 4 Temporary weld 5 Eccentric electrode 6 Welded joint 7 Deep penetration activator

Claims (6)

In narrow gap welding of two steel plates or steel pipes to be welded,
A process of groove processing by gas cutting or plasma cutting;
A step of sandwiching a rectangular insert to the joint part and performing temporary welding to configure the joint part;
A step of applying a deep penetration active agent to the inner surface of the rectangular insert groove in the groove;
Arc welding the joint part;
A back wave welding method comprising: In the case of performing narrow groove welding by performing both-side groove processing of butt welding of two steel plates or cylindrical containers that are to be welded,
A process of groove processing by gas cutting or plasma cutting;
A step of sandwiching a rectangular insert in the center portion and performing temporary welding to form a joint portion;
Applying a deep penetration active agent to the inner surface of the rectangular insert groove in the groove;
Arc welding the joint surface,
Then, from the back side, applying a deep-melt active agent to the inner surface of the groove of the rectangular insert,
Arc welding the joint back surface;
A welding method comprising: The welding method according to claim 1 or 2, wherein the arc welding is performed by TIG welding by a TIG welding apparatus that periodically controls parallel weaving motion in addition to the arc weaving welding method by rotating an eccentric electrode.   The welding method according to claim 1, wherein protection is performed with a backing material or an inert gas to prevent oxidation of the backside molten metal and prevention of falling of the molten metal.   3. The welding method according to claim 1, wherein the target steel material to be welded is stainless steel or low carbon steel.   3. The welding method according to claim 2, wherein the melt-bonded portion formed from the front surface side and the melt-bonded portion formed from the back surface side are overlapped at the center portion of the plate thickness.

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