JP2904338B2 - Tab plate welding method in UO steel pipe production - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a tab plate welding technique in manufacturing UO steel pipe.

[0002]

2. Description of the Related Art First, the role of a tab plate and a method of manufacturing a UO steel pipe will be described. 5 (a) to 5 (f) are views showing a conventional UO steel pipe manufacturing process accompanied by tab plate welding. In (a), tab plates 102... Are provided on both sides of a front end and a rear end of a base material 101.
(... indicates a plurality. The same applies to the following.) The role of the tab plate 102 will be described later. Hereinafter, the groove formation and welding applied to the base material 101 are applied to the tab plate 102, but only the base material 101 will be described for convenience.
(B) is an enlarged cross-sectional view taken along the line bb of (a). Both edges of the base material 101 are cut by an edge planar (not shown) to form grooves 103.

In (c), the vicinity of both edges of the base material 101 is plastically deformed by a press machine 104 to form a C shape as a whole. The operation of the press machine 104 for this purpose is called a C press, and the process is called a C press process. In (d), the base material 101 is further plastically deformed to have a U shape as a whole. In (e), the base material 101 is further plastically deformed,
An O-shape is formed as a whole.

[0004] In (f), both edges of the base material 101 are butted. The grooves 103 in (b) are joined together to form a V-shaped groove (correctly, an X-shaped groove). The outer V-shaped groove is tack-welded. Although not shown, main welding (submerged arc welding is preferable) is performed from the inner surface and the outer surface, and then the tub plates 102 are cut, and then subjected to nondestructive inspection, pipe expansion, water pressure test, and nondestructive test. , Through chamfering into steel pipe products.

That is, the tab plate 102 is a member for reliably performing the main welding. If the main welding is performed without attaching the tab plate 102, welding defects are likely to occur at the welding start and end portions. Because it becomes. The UO steel pipe is given a name because it undergoes a process of plastically deforming the base material 101 in the order of U → O.

For example, Japanese Patent Application Laid-Open No. Sho 59-225899, entitled "Tab Plate Welding Method in UO Steel Pipe Manufacturing" and Japanese Patent Application Laid-Open No. Sho 59-22598, Japanese Patent Application Laid-Open No. Sho 59-225899 disclose the method of mounting a tab plate in UO steel pipe manufacturing. Has been proposed. The above is, as shown in FIG.
This is a technique for applying solid materials 4 and 4 to the tab plate 2 to prevent the molten metal from flowing down. Fig. 5 (a), (b)
As shown in FIG. In the above, the tab plate is attached inclining downward in advance, and consideration is given so that it becomes flush with the base material after the main welding. The groove shape is a groove shape.

[0007]

However, in the conventional UO steel pipe manufacturing process with a tab plate, the following inconveniences sometimes occur. These are (1) the dropping of the tab plate and (2) the tab opening phenomenon. The drop of the tab plate in (1) is insufficient in welding adhesive strength, and can be dealt with by increasing the groove angle to increase the amount of weld metal. FIG. 6 is a plan view showing a tab opening state that has conventionally occurred. When edges of the base material 101 are abutted against each other, the tab plates 102 may sometimes open at an angle α. In this case, predetermined main welding cannot be performed, so that it is necessary to correct the welding, and it is necessary to check whether or not the angle α is within an allowable range, thereby causing a disadvantage that productivity is reduced.

[0008]

The inventors of the present invention have investigated the process retroactively. As a result, it was found that the tab plate was inclined in the C press step. Further, it has been found that the extra height of the weld bead is the cause. That is, the extra bank protruding from the base material is first pressed by the C-breathing machine, and this pressing causes the bead to be plastically deformed also in the direction perpendicular to the pressing direction.
Thus, the inventors have found that the tab plate rotates slightly but horizontally. If an attempt is made to increase the amount of penetration to prevent the above (1), the above (2) is likely to occur this time. Thus, the present inventors have succeeded in obtaining satisfactory results by taking the following measures.

[0009] As a means, when attaching the tab plate into the base material for the UO pipes manufactured by forming a groove on the tab plate side, soluble
Deposited metal to fill the groove by adjusting the contact current value is that welding so as not to protrude from the outer surface of the base material.

[0010] The groove has a root surface height of 3 mm.
As described above, the tabs are formed by a machining method so as to have a thickness of 40% or less.

[0011]

The base metal and the tab plate are directly pressed by the C press machine by placing the weld metal in the groove.

For this purpose, the groove is accurately finished by a machining method.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. The drawings should be viewed in the direction of reference numerals. FIG. 1 is a plan view of a tab board manufacturing facility according to the present invention. The tab board manufacturing facility 1 includes a material rack 2, a material transfer machine 3, a table 4, a cold saw 5, a clamp 6, and a milling device. 7, a tab plate transfer machine 8, a rack table 9,
It comprises a stock rack 11 and stocker moving means 12.

The operation of the tub plate manufacturing equipment 1 will be described first. One material 14 is transferred from the material rack 2 to the material transfer machine 3.
Is transferred to the table 4 and sent to a predetermined place by the transport operation of the table 4. The predetermined location is a position where the top of the material 14 slightly overlaps the milling device 7. At that position, the blank 14 is clamped by the clamp 6, the groove is machined by the milling device 7, and at the same time, the tab plate is separated from the blank 14 by the cold saw 5 (to be described in detail with reference to FIG. 2). The separated tab plate 20 is transferred to the stock rack 11 by the tab plate transfer machine 8. By moving the stock rack 11 horizontally by the stocker moving means 12, the tab plate 20 is efficiently stocked so as to fill the cells. During or after this, the material 14 is fed by one pitch, and the next groove processing is performed. Therefore, according to the tab plate manufacturing equipment 1, machined tab plates 20 can be efficiently manufactured.

FIG. 2 is a diagram showing the working principle of a milling cutter and a cold saw according to the present invention. The top of a material 14 is cut by a milling cutter 15 to form a groove having a predetermined shape. The tab board (20) of a fixed length is cut out from the material 14 with. FIG.
(C) is a perspective view of the machined tab plate according to the present invention. (A) is a thick plate (for example, 13.0 mm or more) tab plate 20A, and the groove is a root surface 21, a first slope 2
2, a substantially J-shaped groove including the second slope 23. (B)
Is a thick plate (for example, 13.0 mm or more) tab plate 20B, and the groove is a J-shaped groove including a root surface 21 and an arc-shaped surface 24. (C) is a thin plate (for example, less than 13.0 mm) tab plate 20C, and the groove is a groove including a root surface 21 and a first slope 22.

Next, an embodiment and a comparative example according to the above-described method of mounting the tab plate will be described. 4 (a) to 4 (c)
Is an explanatory view of a groove and a margin according to the example and the comparative example, and the symbols used in the following Table 1 are described. (A) is an explanatory view of a groove dimension of the thick tab plate 20A.
, The height of the first slope 22 is X, the angle of inclination is θ1, and the angle of inclination of the second slope 23 is θ2. (B) is an explanatory view of the groove dimension of the thin tab plate 20C, where the height of the root surface 21 is Y, and the inclination angle of the first inclined surface 22 is θ1. (C) is an explanatory diagram of the extra slab. For example, when the groove is filled with two layers of the weld metal 25 by two-pass welding, the weld metal 25, that is, the top of the bead projects from the outer surface 26 a of the base material 26. If it does, it is expressed as (+), and if it is hollow, it is expressed as (-).

[0017]

[Table 1]

[0018] Table 1 is a summary of Examples 1 5 and Comparative Example 1 to 5 shown in the section of groove shape J in FIG. 4 (a)
The groove and the groove indicate the groove in FIG . In the groove processing method, M indicates machining by a milling cutter, and G indicates gas cutting. Y, X, θ1, θ2 in the column of groove dimensions are shown in FIG.
According to (a) and (b), the margin column is based on FIG. 4 (c). The tab board opening defect rate is an appearance rate of the sheet whose opening after the C press is out of tolerance and which requires adjustment. The tab plate drop rate is the ratio of the tab plate that fell before the tack welding and the main welding.

[0019]

Example 1 : The margin was as good as ± 0 mm, but the defect rate of the tab plate opening was 2%, so the evaluation was Δ.
It is. Comparative Example 1 : Margin is +2.5 mm, tab board opening defect rate is 8
The evaluation was poor because it was poor at 0% and the tab plate drop rate was 1.5%.

Example 2 : The tab plate did not fall, and the excess was-
The evaluation was ○ because it was as good as 0.4 mm and the tab plate opening did not require correction. Comparative Example 2 : Extra 2.0 mm, tab plate opening 45%,
Since the drop rate of the tab plate was 1.0%, the evaluation was x.

Example 3 : The evaluation was ○ because the tab plate did not fall and the opening of the tab plate did not require correction. Comparative Example 3 : The evaluation was "Poor" because the excess was 1.5 mm, the tab plate opening was 5%, and the tab plate drop rate was 1.0%.

Example 4 : The evaluation was ○ because the tab plate did not fall and the opening of the tab plate did not require correction. Comparative Example 4 : The tab plate did not drop, but the tab plate opening was 4
The evaluation is △ because it was accepted.

Example 5 : The evaluation was ○ because the tab plate did not fall and the opening of the tab plate did not require correction. Comparative Example 5 : Since the margin was +1.6 mm, the tab plate opening was 2%, and the tab plate drop rate was 0.5%, the evaluation was x.

From Table 1, it can be seen that in the embodiment, the root surface was correctly secured by machining the groove, and the molten metal was effectively prevented from falling off, so that the joining strength was increased and the tab plate could be prevented from dropping. You can see that Further, in the example, since the margin was negative, the opening of the tab plate was suppressed.

The height of the root surface was 3 mm in the thinnest embodiment of the first embodiment . If it is 3 mm or more, good results can be obtained.
It was confirmed that it could be done. Further, in terms of strength, there is no fear that the tab plate will fall if only 50% of the thickness of the tab plate is effectively bonded. However, in the present invention, since the surplus is made negative, the only way to secure 50% is to allocate the remainder to the surplus minus 10% and the root surface 40%. Therefore, the maximum value of the root surface is set to 40% of the thickness of the tab plate.

The groove processing method is not only milling cutter,
A well-known machining method such as bite cutting or milling cutter may be used, or a grindstone may be applied after rough finishing.

[0028]

According to the present invention, the following effects are exhibited by the above method. According to the first aspect, when attaching the tab plate to the base material for manufacturing the UO steel pipe, a groove is formed on the tab plate side, and the weld metal filling the groove is welded so as not to protrude from the outer surface of the base material. Therefore, the inconvenience of horizontal rotation of the tab plate during the C press is eliminated, the tab plate can be maintained in a preferable posture, and occurrence of welding defects can be suppressed.

According to a second aspect of the present invention, since the groove is formed by a machining method, there is no excess or deficiency of the deposited metal, and the height of the root surface is high.
Since the thickness is ensured in the range of 3 mm or more and 40% or less of the thickness of the tab plate, it is possible to prevent the molten metal from being burnt out, to strictly control the amount of the deposited metal, and to prevent the tab plate from falling.

[Brief description of the drawings]

FIG. 1 is a plan view of a tab plate manufacturing facility according to the present invention.

FIG. 2 is a processing principle diagram of a milling cutter and a cold saw according to the present invention.

FIG. 3 is a perspective view of a machined tab plate according to the present invention.

FIG. 4 is an explanatory view of a groove and a margin according to an example and a comparative example.

FIG. 5 is a conventional UO pipe manufacturing process involving tab plate welding.

FIG. 6 is a plan view showing a conventional tab-open state.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Tab plate manufacturing equipment, 5 ... Cold saw, 7 ... Milling device, 15 ... Milling cutter, 20, 20A, 20
B: tab plate, 21: root surface, 25: weld metal, 26:
Base material, 26a: outer surface of the base material.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B21C 37/08

Claims (2)

(57) [Claims] When a tab plate is attached to a base material for manufacturing a UO steel pipe, a groove is formed on the tab plate side to reduce a welding current value.
Tab plate welding method in UO pipe production, characterized in that the deposited metal to fill said groove and welded so as not to protrude from the outer surface of the base material by adjusting. 2. A groove having a height of a root surface of 3 m.
The tab plate welding method according to claim 1, wherein the tab plate is formed by machining so that the thickness is equal to or more than m and equal to or less than 40% of the tab thickness.