JPS6039468B2 - Bottom plate welding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of welding a bottom plate, for example, a welding method for manufacturing the bottom of a large oil storage tank by butting together a plurality of bottom plates.

The bottom of a large oil tank or water storage tank is made by butting together multiple bottom plates and welding adjacent bottom plates together.
It usually has a circular bottom.

FIG. 1 is a plan view of the bottom of a large oil tank, in which a plurality of bottom plates 1 are combined to form a circular shape.

All contact sides 2 of the bottom plate 1 and the adjacent bottom plate 1 are welded. When welding plates together, usually the contact sides of the plates are beveled, and a backing metal is placed on the back side to perform welding. Second
The figure is a cross-sectional view showing the state in which two bottom plates are melted.
The grooves 3, 3 of the two bottom plates 1, 1 are made to correspond to each other, and a backing metal 4 is twilled on the back surface and welded to form a welded part 5.

However, when such welding is performed, concentrated shrinkage stress occurs in the welded part 5, and as a result, the welded bottom plates 1, 1
A downward distortion occurs around the center. In other words, the bottom plate is bent with the metal 4 side convex. Therefore, various methods for correcting this distortion have been attempted and put into practical use in various applications. Figures 3 and 4 show the means of welding the bottom plate that is used when making the bottom of a large subordinate oil tank. Figure 3 is a plan view, and Figure 4 is a part of it. FIG. 3 is an enlarged side view. In both drawings, the bottom plates 1, 1 are welded and fixed via a welded portion 5, and a metal 4 is applied to the back side of the welded portion 5. Further, gate-shaped horses 6, 6 are installed on the surfaces of the bottom plates 1, 1 with their closed parts corresponding to each other, and the legs of the horses 6, 6 are welded and fixed to the surfaces of the bottom plates 1, 1, respectively. . horse 6,6
A strong back 7 consisting of a rectangular parallelepiped is placed in the opening of the
is penetrated. Furthermore, Strongback 7 and Uma 6,6
Wedge-shaped arrows 8, 8 are driven in opposite directions into the gap with the closing part. In this construction method, the welded part 5
Although the distortion of the bottom plates 1, 1 due to the contraction of is considerably corrected,
It still wasn't enough. And the drawback of this method is the bottom plate 1
In order to fix the horse 6 to the surface of the base plate by means of bushing, it was necessary to cut the bottom plate after welding and finish the surface. In addition, the horse 6 was installed across the bottom of the large tank, the strong back 7 was penetrated, and the arrow 8 was inserted.
The work of hammering in these required a great deal of effort, and it was inefficient as they had to be removed after completion. Therefore, an object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to provide a bottom plate welding method that uses a relatively simple jig to correct the distortion caused by shrinkage of the welded part, and that does not require post-work repairs. It is about providing.

That is, when welding a plurality of bottom plates, the structure of the present invention is to weld and fix the bottom plate and the backing metal on one side of two adjacent bottom plates by hitting the rhombus metal on the back side of the groove. By welding and fixing one side of the curved plate having an arc-shaped cross section to the back of the backing metal with the convex portion facing downward, the curved plate supports two adjacent bottom plates through the metal fitting. After that, the groove portion of the bottom plate is welded, and after all the welding is completed, a load is applied to the top surface of the bottom plate to make the crab-shaped plate flat. Hereinafter, the construction method of the present invention will be specifically explained with reference to the drawings.

FIG. 5 is a side view showing a bottom plate welded by the construction method of the present invention, and FIG. 6 is a sectional view taken along the line B--B in FIG. 5.

In the figure, the bottom plates 1, 1' are adjacent to each other with their connection parts 3, 3 corresponding to each other, and are welded together via a welding part 5.

The backing metal 4 is abutted on the back side of the welded part 5, and is welded only to the bottom plate 1' via the welded part 5'. Beneath the backing plate 4, a curved plate 9 having an arc-shaped cross section is installed with its convex portion facing down and its straight sides parallel to the adjacent sides of the bottom plates 1 and 1'. The side of the bottom plate 1' side is welded to the lower surface of the backing metal 4 through the welding part 5''.The convex part of the curved plate 9 is in contact with the asphalt mound 10, and the curved plate 9 is The bottom plates 1 and 1' are supported by the force. Fig. 7 is a side view showing the bottom plate after completing the construction method of the present invention, and the curved plate 9 is crushed by the load from above, and the fan It's flat.

Further, the mound 10 is sunk only at the part where the backing metal 4 and the curved plate 9 are located, and the surfaces of the bottom plates 1 and 2' remain horizontal. Next, the welding method and effects of the present invention will be explained with reference to FIGS. 5 and 6.

First, as shown in FIG. 5, a backing metal 4 and a curved plate 9 are welded to the back side of a bottom plate 1' having a groove on one side.

Next, the other bottom plate 1 is placed in a position where its grooved edge 3 corresponds to the grooved part 3 of the bottom plate 1'. By fixing the other ends of the bottom plates 1, 1' at an appropriate height, the surface of the bottom plate 1.1' can be maintained horizontally. Therefore, mound 1
Only the convex part of the curved plate 9 is in contact with the river, and this curved plate 9 supports the backing metal 4, and the backing metal 4 is in contact with the bottom plates 1 and 1.
′ is supported. Next, the open end 3 of the bottom plate 1, 1'
, 3 are welded downward to form a welded portion 5. At this time, contraction occurs due to the molten saddle, and the bottom plates 1 and 1' try to bend downward in a convex direction centering on the welded part 5, but this part is supported by the bending plate 9, and the bottom plates 1 and 1' ，
Because of its own weight, a force is acting on plate 1' that tries to bend it in an upwardly convex direction around welded part 5, so these forces cancel each other out, and as a result, the surfaces of bottom plates 1 and 1' are horizontal. It is maintained. The bottom of a large oil tank is made by combining bottom plates of appropriate sizes, and the seams of all the bottom plates are welded using the construction method shown in Figures 5 and 6. Once all the welding work is completed, a load is applied from above the entire surface of the bottom plate, but this method of applying the load is usually
A method is used to apply water pressure to the entire bottom plate by filling the tank with water during a water filling test. When a hydraulic load is applied to the waist plate, since only one side of the bent plate 9 is welded and is in a cantilevered state, its free end side is rolled, and the bent plate 9 is pressed against the backing plate as shown in FIG. It transforms into Kohei between 4 and mound 10. At this time, the backing metal 4 and the deformed Kenkyoku plate 9 are embedded in the mound 10, the surfaces of the bottom plates 1, 1' are kept horizontal, and almost no distortion occurs due to welding. Since the present invention uses the construction method described above, it has the following advantages not found in conventional construction methods.

○} In the conventional method, distortion occurred due to welding, and the bottom plate was bent with the welded part upward, but in the method of the present invention, the bending plate and the bottom plate are corrected by using their own weight, and the mutual force is absorbed. are canceled out, and almost no distortion occurs.

{2) In the conventional construction method using strong backs, fittings such as ridges are welded to the surface of the bottom plate, which requires labor to attach, remove, and polish the surface. Since there is no need to attach any jigs to the structure, there is no need for repairs, which shortens construction time and reduces construction costs.

{Character 3 In the conventional process, it was necessary to provide an expansion point at the welded part, but in the present invention, the weld is bent upward by the amount of shrinkage due to welding, so there is no need to provide an expansion point.

{4) Since no jig is installed on the surface of the bottom plate, working conditions are improved and semi-automatic or fully automatic welding is possible.

'5} The cod curved board is extremely easy to construct because it can be deformed by hydraulic load using a water test.

[Brief explanation of the drawing]

Figure 1 is a plan view of the bottom plate of a large tank, Figure 2 is a sectional view of the welded part of the bottom plate, Figure 3 is a plan view of the welded part of the bottom plate in the conventional construction method, and Figure 4 is an enlarged view of a part of the welded part. Fig. 5 is a side view of the bottom plate welded part in the construction method of the present invention, Fig. 6 is a cross-sectional arrow view taken along line B-B in Fig. 5, and Fig. 7 is the bottom plate welded part after the construction method of the present invention has been completed. FIG. 1...Bottom plate, 2...Contact side, 3...
...Bevel, 4...Backing metal, 5...Welded part, 6...Horse, 7...Strong back, 8...Arrow, 9...curved board, 10...mound. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] 1 When welding multiple bottom plates, weld and fix the bottom plate and the backing metal on one side of the two adjacent bottom plates by contacting the backing metal on the back side of the groove, and also By welding and fixing one side of the curved plate having an arcuate cross-sectional shape with the convex portion facing downward, the curved plate supports two adjacent bottom plates via the backing metal, and then the grooved part of the bottom plate is fixed. A bottom plate welding method characterized by flattening the curved plate by applying a load to the top surface of the bottom plate after all welding is completed.