JPH071046A - Formation of seamless complex membrane and partial die used therefor - Google Patents

Abstract

PURPOSE:To form a seamless complex membrane having plural membrane crossing parts in small strain. CONSTITUTION:In a method for forming the seamless complex membrane by partially pressing while gradually feeding a slender blank in oder, partial dies 10, 20 for forming a corrugation having different depths in the membrane are provided. Graduation parts 12, 22, in which deformed quantity is gradually reduced, are arranged at the boundary part between the partial dies so that the deformation of the membrane with the partial dies is scarcely developed at the boundary part in the following press position. While gradually feeding the blank by using the partial dies, the blank is partially pressed to form the seamless complex membrane having shallow corrugation. Successively, by using the partial dies, the seamless complex membrane is partially pressed while feeding in order to form the seamless complex membrane having deeper corrugation.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a cryogenic tank,
More specifically, it relates to a method for molding a seamless composite membrane for an LNG tank and a partial mold used for the method.

[0002]

2. Description of the Related Art Cryogenic tanks are, for example, cryogenic (-162
It is a tank for storing LNG (liquefied natural gas) of ℃), and various types such as underground type, aboveground type, and ship-mounted type are being constructed. FIG. 4 is an overall view of an underground LNG tank, which is a hollow cylindrical tank body 1 with an open top.
And a roof 2 that covers the opening of the tank body 1.
The tank main body 1 includes a concrete skeleton 3 buried underground, a cold insulator 4 attached to the inner surface of the skeleton 3, and a membrane 5 attached to the inner surface of the cold insulator 4. The inside of the membrane 5 is directly filled with liquid LNG. Underground LNG tanks have become larger in size as the demand for LNG has increased, and tanks with a diameter of 50 m or more and a liquid depth of 40 m or more have been constructed. FIG. 5 is a partially enlarged view of the membrane. The membrane 5 is formed by pressing a metal plate having a thickness of about 2 mm, and directly contacts the LNG to prevent the leakage thereof, and transmits the liquid pressure of the LNG to the body 3 via the cold insulating material 4. In addition, the membrane 5 has a large number of corrugations 6 (corrugated portions) at substantially regular intervals (for example, 2 m) so as to absorb thermal contraction (thermal expansion) and withstand liquid pressure.
Is provided, and the intermediate portion of the corrugation 6 is fixed to the skeleton 3 (not shown) by the membrane anchor 7. FIG. 6 is a diagram showing a cross-sectional shape of two corrugations 6 having different waveforms. The arrows in the figure show the action of hydraulic pressure, and arc-shaped corrugations must withstand this hydraulic pressure. Further, the broken line in the figure shows the heat shrinkage state of the membrane fixed to the body 3 by the membrane anchor 7, and when the corrugation interval is, for example, about 2 m, it is about 6 mm.
There is a heat shrinkage of mm, and this heat shrinkage amount is corrugated 6
It is necessary to absorb it by the deformation of. In order to satisfy these two functions, the corrugation has a cross-sectional shape that gradually changes as the liquid depth increases, from a shape with a large arc that is easy to machine (A) to a shape with a small arc that is difficult to machine (B). FIG. 7 is an enlarged perspective view of the corrugation intersection portion 8 where the corrugations intersect. Corrugation intersection 8
Is molded into a complicated shape as shown in the figure. That is, since the membrane is repeatedly subjected to a temperature difference of about 200 ° C. from the boiling point of LNG of about −162 ° C. to room temperature, if a large stress is partially generated during thermal contraction, fatigue strength due to repeated thermal contraction decreases, The service life of the entire cryogenic tank may be shortened. For this reason, the corrugation intersections are shaped so that the lengths in any direction along the surface are the same so that smooth heat shrinkage is possible.

[0003]

The membrane (FIG. 5) of the LNG tank can be constructed as a whole by welding a large number of membranes (FIG. 7) around each other.
That is, by pressing a membrane with one corrugation intersection, processing the periphery into an appropriate shape (rectangular or fan-shaped), then attaching it to the inner surface of the cold insulating material 4 at the construction site, and welding the periphery to the entire membrane. Can be completed. However, the welded part of the membrane is
There are problems that defects such as poor joints and reduction in strength are likely to occur, and distortion is likely to occur due to heat during welding.
The length of the welded part of the membrane is, for example, 14
With an LNG tank of 10,000 m ³ (diameter 64 m, liquid depth 45), the total length reaches 25,000 m or more, and it takes a long construction period and many skilled welding workers to carry out this entire welding at the construction site. There was a problem. In order to solve such a problem, it has been conventionally desired to integrally form a seamless composite membrane having a plurality of corrugation intersections by press molding. However, the interval between corrugations 6 is large, for example, about 2 m, and therefore the total length of the composite membrane having a plurality of corrugation intersections (for example, 4) is extremely long (for example, about 8 m), and even if a large press machine is used, the die Was too large to be integrally molded. On the other hand, when a long material (for example, about 9 m) is partially pressed by a partial mold with one corrugation crossing part, and the whole seamless composite membrane is formed by repeating this process, distortion due to partial pressing causes However, there is a problem that a wrinkle is formed at the boundary between the molded portion and the flat portion to be pressed next, and the next pressing cannot be performed. The present invention was created to solve such problems. That is, an object of the present invention is to provide a method for forming a seamless composite membrane that can form a seamless composite membrane having a plurality of corrugation intersections with a small strain, and a partial mold used for the method.

[0004]

According to the present invention, in a method for forming a seamless composite membrane by partially pressing while sequentially feeding an elongated material, a partial mold for forming a corrugation on the membrane is provided. In order to prevent the membrane from being deformed by the partial mold at the boundary between the next press position and the boundary, the boundary part of the partial mold is provided with a blurring portion where the amount of deformation gradually decreases. To form a shallow corrugated seamless composite membrane, then press
A method for forming a seamless composite membrane, wherein the seamless composite membrane is sequentially fed using the partial mold to partially press to form a deeper corrugated seamless composite membrane. . It is preferable that the partial molds have a single corrugation intersection at a position aligned with each other. Furthermore,
According to the present invention, there is provided a partial mold for forming a seamless composite membrane by partially pressing while feeding a long and narrow material, wherein the partial mold has a boundary between the deformation of the membrane and the next press position. There is provided a partial mold for a seamless composite membrane, which has a blurring portion in which the amount of deformation is gradually reduced so that it hardly occurs in the portion. According to a preferred embodiment of the present invention, the partial mold has a single corrugation intersection.

[0005]

According to the method and apparatus (partial mold) of the present invention described above, since the boundary part of the partial mold is provided with the blurring portion where the deformation amount is gradually reduced, the elongated material is sequentially fed while being partially pressed. Even if the seamless composite membrane is formed by the above, the membrane is hardly deformed at the boundary with the next press position. Therefore, if a partial corrugation is provided, a shallow corrugation is first molded using this partial mold, and then deep corrugations are sequentially molded, a seamless composite membrane of deep corrugation can be molded with a small strain. In particular, if the partial mold has a single corrugation intersection at a position aligned with each other, the deformation due to press molding by the partial mold is relatively small, and a deep corrugation seamless composite membrane having a plurality of corrugation intersections. Can be molded relatively easily.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. In the drawings, common parts are designated by the same reference numerals and used. FIG. 1 is an overall perspective view of a partial mold according to the present invention, (A) showing an upper mold and (B) showing a lower mold. The partial mold according to the present invention is composed of an upper mold 10 and a lower mold 20, and is used to form a seamless composite membrane by partially pressing an elongated material while sequentially feeding it in a direction shown by an arrow in the figure. The upper mold 10 and the lower mold 20 have blurring portions 12 and 22 at which the amount of deformation gradually decreases so that the deformation of the membrane hardly occurs at the boundary with the next press position. Further, each partial mold has a single corrugation intersection 14, 24.

Next, a method for forming a seamless composite membrane according to the present invention will be described below. First, the partial molds 10 and 12 described above are prepared. Then, while partially feeding the material using the partial mold to form a shallow corrugation seamless composite membrane, then using this partial mold to sequentially feed the seamless composite membrane Partially pressed to form a deeper corrugated seamless composite membrane.

FIG. 2 is a perspective view of the membrane 5 in which the shallow corrugation is partially formed, and FIG.
1 is a perspective view of a completed seamless composite membrane having a plurality of corrugation intersections 8. FIG. As can be seen from FIGS. 2 and 3, according to the method and apparatus of the present invention described above, the blurring portion 1 in which the amount of deformation gradually decreases at the boundary portion of the partial mold.
Since Nos. 2 and 22 are provided, even if the thin and long material is sequentially fed and partially pressed to form the seamless composite membrane, the membrane is hardly deformed at the boundary with the next press position. Therefore, a partial mold is provided, and a shallow corrugation is first formed using this partial mold,
By sequentially forming deep corrugations, a seamless composite membrane of deep corrugations can be formed with a small strain. In particular, if the partial molds have a single corrugation intersection in a position aligned with each other, the deformation due to press molding by the partial mold is small and a deep corrugated seamless composite membrane having multiple corrugation intersections is compared. It can be molded easily.

[0009]

Therefore, the molding method of the present invention and the partial mold used therein have an excellent effect that a composite membrane having a plurality of corrugation intersections can be molded with a small strain.

[Brief description of drawings]

FIG. 1 is an overall perspective view of a partial mold according to the present invention.

FIG. 2 is a perspective view of a membrane in which a shallow corrugation is partially molded.

FIG. 3 is a perspective view of a completed seamless composite membrane with multiple corrugation intersections.

FIG. 4 is an overall configuration diagram of an underground LNG tank.

FIG. 5 is a partially enlarged view of the membrane.

FIG. 6 is a diagram showing a cross-sectional shape of two corrugations having different waveforms.

FIG. 7 is an enlarged perspective view of a corrugation intersection.

[Explanation of symbols]

 1 Tank Main Body 2 Roof Part 3 Body 4 Cooling Material 5 Membrane 6 Corrugation 7 Membrane Anchor 8, 14, 24 Corrugation Intersection 10 Upper Mold 20 Lower Mold 12, 22 Blurred Part

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B30B 15/02 B 9346-4E F17C 3/06 7367-3E

Claims (4)

[Claims] 1. A method for forming a seamless composite membrane by partially pressing while feeding an elongated material in sequence, comprising a partial mold for forming a corrugation on the membrane, and the deformation of the membrane by the partial mold is as follows. A blur part is provided at the boundary of the partial mold so that the amount of deformation is gradually reduced so that it hardly occurs at the boundary with the press position, and the partial mold is used to sequentially press the material while sequentially feeding the material. Forming a shallow corrugation seamless composite membrane, and then partially pressing while sequentially feeding the seamless composite membrane using the partial mold to form a deeper corrugation seamless composite membrane,
A method for forming a seamless composite membrane, which is characterized in that 2. The method for molding a seamless composite membrane according to claim 1, wherein the partial molds have a single corrugation intersection at a position aligned with each other. 3. A partial mold for forming a seamless composite membrane by partially pressing while feeding a long and narrow material in sequence, wherein the partial mold has a boundary portion between the deformation of the membrane and the next press position. A partial mold for a seamless composite membrane, characterized in that it has a blurring portion where the amount of deformation gradually decreases so that it hardly occurs at the boundary. 4. The partial mold for a seamless composite membrane according to claim 3, wherein the partial mold has a single corrugation intersection.