KR100974147B1 - An Apparatus and Method for Forming Corner Pieces Membrane for LNG Storage Tank - Google Patents

Abstract

The present invention relates to a method and apparatus for forming a cornerpiece membrane for a liquefied natural gas storage tank.

Forming method of the corner piece membrane for the LNG storage tank of the present invention is formed in the shape of a large-large corner piece membrane unlike the conventional method for forming a small-small corner piece membrane or a large-small corner piece membrane Since no wrinkles are generated in the portion deformed from the wrinkle portion to the flat portion because the process is not performed, the Small-Small corner piece membrane or the Large-Small corner piece membrane having good flatness of the entire flat portion can be formed. In addition, even if it is not molded into the shape of a large-large corner piece membrane, the folding of the second crease or notch does not occur, so the small-small corner piece membrane or the large-small corner piece having excellent durability and stability is not generated. It is possible to provide a piece membrane.

Cornerpiece membrane, first wrinkles, second wrinkles, notches, large wrinkles, small wrinkles, first pre-wrinkles, second pre-wrinkles, flat, shrinking, bending, cutting

Description

Method and apparatus for forming corner piece membrane for LNG storage tank {An Apparatus and Method for Forming Corner Pieces Membrane for LNG Storage Tank}

The present invention relates to a method and apparatus for forming a cornerpiece membrane for a liquefied natural gas storage tank, and in particular, a small-small type having good flatness of the entire flat portion without undergoing a molding process in the shape of a large-large cornerpiece membrane. A method and apparatus for forming a cornerpiece membrane or a large-small cornerpiece membrane.

Liquefied natural gas has a boiling point of -162 ° C under atmospheric pressure, and is generally stored in a liquid storage tank having a thermal insulation function for transportation or storage. The storage tank consists of a membrane having a material resistant to low temperature brittleness. Membrane is designed to expand and contract in response to changes in liquefied natural gas, temperature and load, and to perform a sealing function to prevent leakage of liquefied natural gas. The membrane consists of a thin membrane having a thickness of about 0.5 to 1.2 mm.

In general, membranes used in LNG storage tanks include flat membranes installed on the wall and the bottom of the storage tank, cornerpiece membranes for connecting and sealing the wall and the bottom, and anchoring membranes for fixing the membranes. A cap piece membrane for blocking the end of the membrane, and a connecting piece membrane for assisting the connection between the membrane and the membrane weld.

The present invention relates to a method and apparatus for forming a cornerpiece membrane among the membranes disclosed above.

1 schematically illustrates a cornerpiece membrane. The corner piece membrane 10 is formed with first wrinkles 11 and 11 'in the longitudinal direction, and is bent at a predetermined angle in the middle portion thereof to bisect the first wrinkles 11 and 11'. The flat part 14 extends from the width direction both ends of the 1st wrinkle part 11 and 11 '. The second wrinkles 12 and 12 'are formed between the first wrinkles 11 and the first wrinkles 11', and the first wrinkles 11 and 11 'and the second wrinkles 12 , 12 ', a recess 17 and 17' are formed to connect between the ridge lines of the first corrugations 11 and 11 'and the ridge lines of the second corrugations 12 and 12'. A notch 13 is formed between the second wrinkled portion 12 and the second wrinkled portion 12 '.

The flat portion 14 of the cornerpiece membrane 10 includes a first flat surface 14a extending from the middle portion of the cornerpiece membrane 10 to the stepped portion 15, and the cornerpiece membrane (from the stepped portion 15). And a second flat surface 14a 'extending to the longitudinal end of 10). A stepped portion 15 is formed between the first flat surface 14a and the second flat surface 14a ', and the first flat surface 14a is slightly lower than the second flat surface 14a'. Has The stepped portion 15 is also formed in the first pleated portions 11 and 11 ', and the stepped portions 15 on both sides of the first pleated portions 11 and 11' are connected to each other.

Corner portions 16c are formed between the first side end portions 16a corresponding to the widthwise ends of the cornerpiece membrane 10 and the second side end portions 16b corresponding to the longitudinal ends, respectively.

The corner piece membrane 10 is generally divided into three types according to the size of the first wrinkles 11 and 11 '. That is, a large-large type (for example, AP7) in which both of the first wrinkles 11 and 11 'are major wrinkles, and one of the first wrinkles 11 are large wrinkles and the other first wrinkles 11 'is a small-small type (for example, AP1-31), which is a small wrinkle, and a small-small type (for example, AP1-31), in which both of the first wrinkles 11, 11' are small wrinkles. 21) There is.

On the other hand, the cornerpiece membrane 10 is a 90-degree cornerpiece membrane, 108-degree cornerpiece membrane, 135-degree cornerpiece membrane, according to the angle at which the first pleats 11, 11 'is bent in the longitudinal direction, 90 degree reverse cornerpiece membrane and so on. The cornerpiece membrane shown in FIG. 1 corresponds to a 90 degree cornerpiece membrane in which the first corrugations 11, 11 ′ are bent 90 degrees in the longitudinal direction.

FIG. 2 is a cross-sectional view taken along the line A-A of the cornerpiece membrane shown in FIG. As shown in FIG. 2, the first corrugations 11 and 11 ′ of the corner piece membrane 10 have upper rounding portions R1 and side roundings formed on both sides of the upper rounding portions to prevent stress concentration. It consists of a part R2, the bottom rounding part R3 which connects the side rounding part R2, and the flat part 14. As shown in FIG.

The first wrinkle portion is generally divided into a large wrinkle portion and a small wrinkle portion having a smaller dimension than the large wrinkle portion. As an example, GTT's MarkIII type generally has the following values.

First wrinkles

R1
R2
R3
E
h
Large wrinkle part

9.4
65.4
8.4
38.5
54.5
Small wrinkles

8.4
38.4
8.4
26.5
36

(Unit: mm)

Figures 3 (a) to 3 (l) show, in each step, a conventional method for producing a Small-Small type cornerpiece membrane, in particular a Small-Small type 90 degree cornerpiece membrane.

In order to manufacture the Small-Small type cornerpiece membrane according to the conventional method, first, as shown in FIG. 3 (a), the plate is cut to fit the desired cornerpiece membrane size, and then, as shown in FIG. Bending the plate at an angle, for example about 105 degrees.

The bent plate is formed by the large-large cornerpiece membrane mold apparatus (first mold) shown in FIGS. 4 (a) and 4 (b), and the large-large cornerpiece membrane shown in FIG. 3 (c). It is primarily molded into the shape of. The first molded part (primary molded part) formed in the shape of a large-large corner piece membrane has a first wrinkle part (11, 11 '), a second wrinkle part (12, 12'), and a flat part (14). Are each formed. In this case, the first wrinkles 11 and 11 'have a size corresponding to the major wrinkles, and the second wrinkles 12 and 12' are formed between the first wrinkles 11 and 11 ', It is connected to each other without the notch 13 in the middle.

The primary molded product is subjected to a shrinking process by the shrinking die apparatus shown in FIG. In the shrinking process, as shown in Fig. 3 (d), the first wrinkles 11 and 11 'of the primary molded part are reshaped from the major wrinkles to the small wrinkles, respectively, and the flat portion 14 Flatness is corrected.

The molded article that has undergone the shringing process is subjected to the second molding process by a second mold (not shown). In the second molding process, the deformation angle generated in the molded product is corrected through the shrinking process as shown in Fig. 3E.

The molding (secondary molding) that has undergone the second molding process is subjected to the third molding process by a third mold (not shown). In the third molding process, the longitudinal angle of the secondary molded product is bent at a predetermined angle, for example, 90 degrees, as shown in Fig. 3f. In this process, the notch 13 is formed between the second corrugations 12 and 12 '. The moldings after the third molding process (the third moldings) finally have the approximate shape of the Small-Small cornerpiece membrane.

The third molded article is then subjected to a first side end portion 16a, a second side end portion 16b, a first side end portion 16a, and a second side as shown in Figs. 3g to 3i. The first to third cutting processes are respectively performed to cut the corner portions 16c between the end portions 16b. After the third cutting process, a process of removing burrs formed on the cutting surface of the molding (refer to FIG. 3j) is followed by a jogling process of forming the step 15 shown in FIG. 1. (See figure (3k)). After the jogling process, the final step of inspecting the molded Small-Small cornerpiece membrane for defects is the final finished product. The method of manufacturing the large-small cornerpiece membrane is small-small type, except that in the shrinking process, only one of the first wrinkles 11 and 11 'having the size of the large wrinkle part is reshaped into the small wrinkle part. It is substantially the same as the method for producing the cornerpiece membrane.

However, there are some problems in the conventional method of manufacturing such a small-small cornerpiece membrane or a large-small cornerpiece membrane. First, in the conventional Small-Small type cornerpiece membrane or Large-Small type cornerpiece membrane manufacturing method, the plate is first molded into the shape of a Large-Large type cornerpiece membrane, and as shown in FIG. 3 (d). Similarly, since the first wrinkled portions 11 and 11 'of the primary molded product are reshaped from the large wrinkle portion to the small wrinkle portion using the shrinking die device, the large wrinkle portion is deformed into the flat portion 14. Traces of unnecessary wrinkles are left in the portion X. That is, even if the flatness of the portion X deformed into the flat portion 14 through the shringing process is modified, the flatness of the portion X deformed into the flat portion 14 is not removed because the traces of wrinkles do not disappear completely. Is inevitably bad.

The flat portion 14 is a portion that requires welding when the corner piece membrane 10 is installed in the tank, and when the flatness of the flat portion 14 is poor, this leads directly to a poor welding operation. Poor welding can eventually adversely affect the manufacture and stability of the entire tank in the vessel.

In order to solve the problems of the conventional method of manufacturing such a small-small cornerpiece membrane or a large-small cornerpiece membrane, the first wrinkles 11 and 11 'have a large-large type (large wrinkles). After primary molding into sub-large wrinkles, it is not necessary to reshape into Small-Small type (small wrinkles-small wrinkles) or Large-Small type (large wrinkles-small wrinkles). 1 It is necessary to shape the wrinkles 11 and 11 'into a Small-Small type (small wrinkle part-small wrinkle part) or a Large-Small type (large wrinkle part-small wrinkle part). That is, by forming the first corrugations 11 and 11 'in the desired size and shape from the beginning, the flatness 14 as a whole can be made flat without the portion X deformed into the flat portion 14. You can consider the method.

However, despite this simple solution, the first wrinkles 11 and 11 'are first formed into a large-large type (large wrinkle portion-large wrinkle portion), and then again the small-small type (small wrinkle-small wrinkles). The reason why it was necessary to reshape in a large) or a large-small type (large wrinkle portion-small wrinkle portion) can be seen by referring to Figs. 6 (a) and 6 (b). 6 (a) and 6 (b) do not go through the first step of forming the first pleats 11, 11 'into a large-large type (large-pleat portion-large-pleated portion) immediately without being small-small The lower surface of the molding molded in (small wrinkles-small wrinkles) or Large-Small type (large wrinkles-small wrinkles) is shown, Figure 7 shows the lower surface of the molding after the first molding step. It is.

Small-Small type (small wrinkles-small wrinkles) or Large- without going through the first step of forming the first wrinkles 11, 11 'into a large-large type (large wrinkles-large wrinkles) In the case of a product molded into a small type (large wrinkle portion-small wrinkle portion), as shown in Fig. 6 (a), a part of the second wrinkles 12, 12 'is folded, or Fig. 6 (b) As shown in FIG. 2, the folding between the second pleats 12 and 12 ′ and the notch 13 occurs. The corner joints of the cornerpiece membrane, ie the second pleats 12, 12 ′ and the notch 13, are places that are resistant to angular contraction or expansion in response to the load acting on the cornerpiece membrane. If the above folds occur, the durability or stability of the cornerpiece membrane may be very poor. In addition, the use of such cornerpiece membranes in the manufacture of tanks can have a serious adverse effect on the durability of the tank.

Due to such a problem, the first wrinkles 11 and 11 'are large-large type (large wrinkles-large wrinkles) even though the flatness of the portion X deformed by the flat portion 14 is poor. After primary molding, the small-small corner corner membrane is re-formed into small-small (small wrinkle-small wrinkle) or large-small (small wrinkle-small wrinkle) parts. Alternatively, large-small cornerpiece membranes had to be manufactured.

The present invention is to solve the problems of the prior art, the object of the present invention is not to go through the process of forming a shape of a large-large cornerpiece membrane, the flatness of the entire flat portion of the cornerpiece membrane is good, 2 to provide a method and apparatus for forming a small-small corner piece membrane or a large-small corner piece membrane having excellent durability and stability due to no creases or notches.

Method for forming a corner piece membrane for a liquefied natural gas storage tank according to the present invention for achieving the above object, at least one pair of first wrinkles of the small wrinkles, and the second wrinkles formed between the first wrinkles And a corner piece membrane for a liquefied natural gas storage tank including a flat portion extending from both ends in a width direction of the first corrugation portion, the method comprising: cutting a sheet material into a predetermined size, and cutting the cut sheet material in a longitudinal direction. Bending at an angle, forming a pair of first pre-wrinkles, a second pre-wrinkle between the first pre-wrinkles, and a flat portion extending from both ends in the width direction of the first pre-wrinkle on the bent plate. Forming a first pre-wrinkle portion and a second pre-wrinkle portion of the molding that has undergone the first molding step and the first molding step into first and second wrinkles, wherein at least one of the first pre-wrinkles I include a second molding step of molding into a small wrinkle portion, and a third molding step of bending the molding again in the longitudinal direction, the height of the first preliminary wrinkle portion formed in the first molding step is the second molding step Characterized in that it is lower than the height of the small wrinkle portion formed in.

In particular, the molding method according to the present invention may further include a jogling step of forming a stepped portion in the flat portion of the molded product subjected to the third molding step to divide the flat portion into a first flat surface and a second flat surface. .

In the molding method according to the present invention, one of the pair of first wrinkles is a large wrinkle portion, and in the second molding step, one of the first preliminary wrinkles may be molded into a large wrinkle portion.

In the molding method according to the present invention, it is preferable to further include a shrinking step of correcting the angle of the first wrinkle part after the second molding step, and correcting the profile of the first wrinkle part and the flatness of the flat part.

In the molding method according to the present invention, after the third molding step, further comprising the step of cutting the corners between the end of the flat surface and the flat surface, respectively, and removing the burrs generated in the cut portion It is preferable.

According to another embodiment of the present invention, a preliminary mold apparatus for press forming a preform of a corner piece membrane for a liquefied natural gas storage tank includes a pair of first preliminaries formed in a lengthwise direction on a plate member bent at a predetermined angle in the longitudinal direction. Between the pleats, the second pre-wrinkles formed between the first pre-wrinkles, and between the ridges of the first pre-wrinkle and the ridges of the second pre-wrinkles It is a preliminary mold apparatus which press-processes the preform of the corner piece membrane for liquefied natural gas storage tank by which the recessed part to connect and the flat part extended from the width direction both ends of a 1st pre-pleat part are shape | molded, The recessed lower part of "형상" shape A pair of first upper protrusions corresponding to the first pre-pleated portions of the preform, second upper protrusions corresponding to the second pre-pleated portions, and recesses below A pair of upper depressions corresponding to each other, and a pair of upper flat surfaces extending from both ends in the width direction of the first upper projection to correspond to the flat portion, respectively, are provided with upper molds that can be driven up and down, A first lower projection, a second upper projection, an upper depression, a first lower depression corresponding to the upper flat surface, a second lower depression, and a lower projection, respectively, having a convex upper portion; And a lower mold each having a lower flat surface formed thereon, wherein the height of the first upper protrusion and the first lower depression is lower than that of the small wrinkle portion of the cornerpiece membrane.

In addition, the preliminary mold apparatus has a convex lower portion having a “∨” shape, and has a pair of first upper depressions corresponding to the first preliminary wrinkle portion of the preform and a second preliminary wrinkle portion at the lower portion thereof. A second upper depression, a pair of upper projections corresponding to the recess, and a pair of upper flat surfaces extending from both ends in the width direction of the first upper depression so as to correspond to the flat portion are respectively movable up and down. An upper mold, a concave upper portion having a "의" shape, a first upper depression, a second upper depression, an upper projection, a second lower projection corresponding to the upper flat surface, respectively; The lower protrusion, the lower depression, and the lower flat surface may be configured to include a lower mold is formed.

The apparatus for forming a corner piece membrane for a liquefied natural gas storage tank according to another embodiment of the present invention includes a preliminary mold apparatus and a first preliminary wrinkle portion and a second preliminary wrinkle portion of a preform molded by the preliminary mold apparatus. A main mold apparatus having a female mold and a male mold having a shape corresponding to the small wrinkle portion so as to be molded into a first wrinkle portion and a second wrinkle portion, wherein at least one of the first preliminary wrinkle portions is formed into a small wrinkle portion. It features.

As described above, the present invention does not go through the process of forming into a shape of a large-large cornerpiece membrane, unlike the conventional method of forming a small-small cornerpiece membrane or a large-small cornerpiece membrane. No other wrinkles are generated in the portion deformed from the flat portion to form a small-small corner piece membrane or a large-small corner piece membrane having good flatness of the entire flat portion.

In particular, since the folding of the second pleats or notches does not occur even without forming the shape of the large-large cornerpiece membrane, the small-small cornerpiece membrane or the large-small corner corner having excellent durability and stability. It is possible to provide a piece membrane.

Hereinafter, with reference to the accompanying drawings will be described in detail a method for forming a small-small corner piece membrane or a large-small corner piece membrane according to an embodiment of the present invention.

8 (a) to 8 (l) illustrate each step of a method of forming a small-small corner piece membrane according to an embodiment of the present invention.

In order to manufacture the Small-Small type corner piece membrane according to the molding method of the present invention, as shown in Figure 8 (a) first cut the plate to the size of the desired corner piece membrane, then Figure 8 (b) and Likewise, the plate is bent at a predetermined angle, for example, about 105 degrees.

The bent plate is first molded into the preform shown in Fig. 8 (c) by the preliminary mold apparatus shown in Figs. 9 (a) and 9 (b). The preform is a pair of second pleats 12a which are formed to be connected to each other between the pair of first pre pleats 11a, 11a 'and the first pre pleats 11a, 11a' on the bent plate. , 12a ') and a pair of flat portions 14 extending from both ends in the width direction of the first preliminary corrugations 11a and 11a', respectively. Concave portions 17 and 17 'are formed between the first pre-pleat portions 11a and 11a' and the second pre-pleat portions 12a and 12a 'of the preform to form the first pre-pleat portions 11a and 11a'. The ridge line between the ridge line and the ridge line of the second preliminary wrinkle portion (12a, 12a ').

At this time, when the first preliminary pleats 11a, 11a 'are molded into the first pleats 11, 11' through the second molding step, both widthwise ends of the first pleats 11, 11 'are formed. As shown in FIG. 11, the first preliminary wrinkle portion 11a, 11a 'extending from to prevent unnecessary unnecessary wrinkles from being generated in the portion Y deformed into the flat portion 14. The heights of 11a and 11a 'are molded lower than the heights of the first wrinkles 11 and 11', which are small wrinkles.

The preform is secondary molded into the molding (secondary molding) shown in Fig. 8D by the main mold apparatus shown in Figs. 10A and 10B. Through the second molding, the first pre-wrinkles 11a, 11a 'and the second pre-wrinkles 12a, 12a' of the preform are formed in the first wrinkles 11, 11 'and the second wrinkles, respectively. (12, 12 ').

Conventionally, the first wrinkles 11 and 11 'of the primary molded article having a large-large corner piece membrane shape corresponding to the first preliminary wrinkles 11a and 11a' of the present invention correspond to the major wrinkles. Therefore, when re-molding it to the small wrinkles through the shrinking process, there was a problem in which other wrinkles are generated in the portion X which is a wrinkle portion and is deformed into a flat portion. However, in the present invention, since the heights of the first preliminary wrinkles 11a and 11a 'are formed to be lower than the heights of the first wrinkles 11 and 11', which are small wrinkles, the first preliminary wrinkles 11a and 11a are formed. Even if ') is re-formed into the first wrinkles 11 and 11', which are small wrinkles, as shown in FIG. 8 (d), the first preliminary wrinkles 11a and 11a 'are used, and the flat portion 14 No wrinkles occur in the portion Y to be deformed, so the flatness of the flat portion 14 is superior to the conventional method.

The secondary molding is subjected to a shrinking process by the shrinking die device shown in FIG. In the shrinking process, as shown in Fig. 8E, the profile of the first wrinkles 11 and 11 'of the secondary molded product is finally formed, and the flatness of the flat part 14 is corrected. .

The molded article that has undergone the shringing process is subjected to the third molding process by a third mold (not shown) as in the related art. In the third molding process, the longitudinal angle of the molding which has undergone the shringing process as shown in Fig. 8f is bent at a predetermined angle, for example 90 degrees for a 90 degree cornerpiece membrane. The moldings after the third molding process (the third moldings) finally have the approximate shape of the Small-Small cornerpiece membrane.

The third molded article is then subjected to a first side end portion 16a, a second side end portion 16b, a first side end portion 16a, and a second side as shown in Figs. 8g to 8i. The first to third cutting processes are respectively performed to cut the corner portions 16c between the end portions 16b. After the third cutting process, a process of removing burrs formed on the cutting surface of the molding (refer to Fig. 8j) is followed by a jogling process of forming the step 15 shown in Fig. 1. (See FIG. 8k). After the jogling process, the final step of inspecting the molded Small-Small cornerpiece membrane for defects is the final finished product. The method of manufacturing the large-small cornerpiece membrane is substantially different from the method of manufacturing the small-small cornerpiece membrane, except that only one first pre-pleat portion 11a is formed into a small wrinkle portion in the second molding step. Same as

 Hereinafter, a preliminary die apparatus for pressing a preform of the corner piece membrane for a liquefied natural gas storage tank according to another embodiment of the present invention will be described in detail.

The preliminary mold apparatus 20 of the present invention includes an upper mold 31 which can be driven up and down, and a lower mold 21 corresponding to the upper mold. The lower mold 21 has a convex top 22 in the shape of a "∧", and a pair of first lower depressions corresponding to the first pre-pleat portions 11a and 11a 'of the preform on the upper portion 22. 11b, 11b ', a pair of second lower depressions 12b, 12b' corresponding to the second preliminary corrugations 12a, 12a ', and as long as they correspond to the recesses 17, 17'. A pair of lower projections 17b and 17b 'and a pair of lower flat surfaces 14b extending from both ends in the width direction of the first lower depressions 11b and 11b' are formed to correspond to the flat portions 14, respectively. All. The upper mold 31 has a concave lower portion (not shown) having a "∧" shape, and at the lower portion thereof, the first lower recesses 11b and 11b 'of the lower mold 21 and the second lower recesses 12b, 12b '), second upper protrusions (not shown), second upper protrusions (not shown), and upper depressions (not shown) corresponding to the lower protrusions 17b and 17b', and the lower flat surface 14b, respectively. ) And an upper flat surface (not shown) are formed, respectively.

The preliminary mold apparatus 20 according to the present invention, when at least one of the first preliminary pleats 11a, 11a 'is subsequently molded into the first pleats 11, 11', which are small wrinkles, the first preliminary pleats The heights 11a and 11a 'of the part are molded to be lower than the heights of the first wrinkles 11 and 11', which are small wrinkles. Accordingly, other wrinkles may be applied to the portion Y of the first preliminary wrinkle portions 11a and 11a 'extending from the widthwise ends of the first wrinkle portions 11 and 11', which are small wrinkle portions, and deformed into the flat portion 14. Is not generated.

The upper mold 31 and the lower mold 21 have a convex lower portion of the "mold" shape, and the lower mold may have a concave upper part of the "m" shape, and the upper mold 31 and Protrusions, depressions, etc. formed in the lower mold 21 may be formed in the opposite direction.

The apparatus for forming a cornerpiece membrane for a liquefied natural gas storage tank according to another embodiment of the present invention includes the preliminary mold apparatus 20 and the main mold apparatus 40. The main mold apparatus 40 connects the 1st pre-wrinkles 11a and 11a 'and the 2nd pre-wrinkles 12a and 12a' of the preform shape | molded by the pre-mold apparatus 20 to the 1st wrinkle part ( 11, 11 ') and second wrinkles 12, 12', wherein at least one of the first pre-pleat portions 11a, 11a 'can be molded into the first wrinkle portion of the fine wrinkles, It consists of the female mold 50 and the male mold 60 which have a shape corresponding to the non-corresponding 1st wrinkle part.

In this case, one of the pair of first wrinkles 11 and 11 ′ may be a large wrinkle portion, and the main mold apparatus 40 may have a female mold 50 having a shape corresponding to the first wrinkle portion that is the large wrinkle portion. It may be composed of a male mold (60).

The embodiments of the present invention described above are presented for illustrative purposes, and are not intended to limit the invention to these specific procedures and forms, and many variations and modifications may be made thereon.

1 shows a schematic view of a 90 degree cornerpiece membrane.

FIG. 2 is a cross-sectional view taken along the line A-A of the 90 degree cornerpiece membrane shown in FIG.

Figures 3 (a) to 3 (l) illustrate, in each step, a conventional method for producing Small-Small cornerpiece membranes.

4 (a) and 4 (b) show the upper mold and the lower mold of the conventional Large-Large type corner piece membrane mold apparatus (first mold), respectively.

Figure 5 shows a conventional shringing mold apparatus.

6 (a) and 6 (b) show a small-small mold (small wrinkle portion-small wrinkle portion) without going through a step of forming the first wrinkle part into a large-large type (large wrinkle portion-large wrinkle portion). Or the lower surface of the moldings molded in a Large-Small type (large wrinkles-small wrinkles).

FIG. 7 shows a bottom surface of the molded article that has been subjected to the step of forming the first wrinkle part into a large-large type (large wrinkle part-large wrinkle part).

8 (a) to 8 (l) illustrate each step of a method for manufacturing a Small-Small corner piece membrane according to an embodiment of the present invention.

9 (a) and 9 (b) show a preliminary mold apparatus according to an embodiment of the present invention.

10 (a) and 10 (b) show an upper mold and a lower mold, respectively, of the main mold apparatus according to the embodiment of the present invention.

Figure 11 compares the height of the first pre-wrinkle portion and the first wrinkles portion that is a small wrinkle portion according to the present invention.

Figure 12 shows a shringing mold apparatus according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

10: 90 degree cornerpiece membrane

11, 11 ': first wrinkles

11a and 11a: first preliminary wrinkles

11b, 11b ': first lower depression

12, 12 ': second crease

12a, 12a: second preliminary wrinkles

12b, 12b ': second lower depression

13: notch

14: flat part

14a: first flat surface

14a ': second flat surface

14b: bottom flat surface

15: step

16a: first side end portion

16b: second side end

16c: corner

17, 17 ': concave

17b, 17b ': lower protrusion

20: spare mold device

21: lower mold

31: upper mold

40: main mold device

50: female mold

60: male mold

Claims (8)

For a liquefied natural gas storage tank comprising a pair of first pleats having at least one small wrinkle portion, a second pleat formed between the first pleats and a flat portion extending from both ends in the width direction of the first pleat. To form a cornerpiece membrane, Cutting the plate into a predetermined size; Bending the cut plate at a predetermined angle in a longitudinal direction; A first molding to form a pair of first pre-wrinkles, a second pre-wrinkle between the first pre-wrinkles, and a flat part extending from both ends in the width direction of the first pre-wrinkle on the bent plate member Steps, A second pre-wrinkle portion and a second pre-wrinkle portion of the molded product that have been subjected to the first molding step into a first wrinkle portion and a second wrinkle portion, wherein at least one of the first pre-wrinkle portions is formed into a small wrinkle portion Car forming step, A third molding step of bending the molding back in the longitudinal direction, The height of the first pre-pleat portion formed in the first forming step is lower than the height of the small wrinkles formed in the second forming step, the method for forming a corner piece membrane for a liquefied natural gas storage tank. The liquefied natural gas storage according to claim 1, further comprising a shrinking step of correcting an angle of the first wrinkle part and correcting a profile of the first wrinkle part and a flatness of the flat part after the second molding step. A method of forming a cornerpiece membrane for a tank. The liquefied natural gas according to claim 1 or 2, wherein one of the pair of first wrinkles is a major wrinkle, and one of the first preliminary wrinkles is molded into a major wrinkle in the second molding step. Method for forming cornerpiece membrane for storage tank. The method according to claim 1 or 2, further comprising a jogling step of forming a stepped portion in a flat portion of the molded product subjected to the third molding step to divide the flat portion into a first flat surface and a second flat surface. A method of forming a cornerpiece membrane for a LNG storage tank. The method of claim 1, wherein after the third molding step, cutting the corners between the end of the flat surface and the flat surface, respectively, and removing the burrs generated in the cut portion. Further comprising a method for forming a cornerpiece membrane for a liquefied natural gas storage tank. A pair of first pre-wrinkles formed in the longitudinal direction on the plate bent at a predetermined angle in the longitudinal direction, a second pre-wrinkle formed between the first pre-wrinkles, and the first pre-wrinkles and the first 2 a liquefied natural gas storage tank having a concave portion formed between the preliminary corrugations and connecting between the ridge line of the first preliminary corrugation portion and the ridges of the second preliminary corrugation portion, and a flat portion extending from the widthwise ends of the first preliminary corrugation portion. It is a pre-mold apparatus for press-processing the preform of the cornerpiece membrane for A pair of first upper protrusions corresponding to the first pre-pleated portion of the preform, a second upper protrusion corresponding to the second pre-pleated portion, and a concave portion having a concave lower portion having a "∧" shape; A pair of upper depressions corresponding to the upper portion, and a pair of upper flat surfaces extending from both ends in the width direction of the first upper protrusion so as to correspond to the flat portion, respectively; A convex top having a "∧" shape and having a first upper protrusion, a second upper protrusion, an upper depression, a first lower depression corresponding to an upper flat surface, and a second lower depression, respectively. And a lower mold having a lower protrusion and a lower flat surface, respectively, And a height of the first upper protrusion and the first lower recess is lower than a height of the small wrinkle portion of the cornerpiece membrane, and preforms the preform of the cornerpiece membrane for the LNG storage tank. A pair of first pre-wrinkles formed in the longitudinal direction on the plate bent at a predetermined angle in the longitudinal direction, a second pre-wrinkle formed between the first pre-wrinkles, and the first pre-wrinkles and the first 2 a LNG storage tank formed between the preliminary corrugations and formed with a recess connecting the ridge lines of the first preliminary corrugations and the ridges of the second preliminary corrugations, and a flat portion extending from both ends in the width direction of the first preliminary corrugations. It is a pre-mold apparatus for press-processing the preform of corner piece membrane for A pair of first upper depressions having a convex lower portion of a “∨” shape, corresponding to the first pre-pleat portion of the preform, a second upper depression corresponding to the second pre-pleat portion; A pair of upper projections corresponding to the recesses, and a pair of upper flat surfaces extending from both ends in the width direction of the first upper depressions so as to correspond to the flat portions, respectively, the upper molds capable of driving up and down; It has a concave upper portion of the "형상" shape, the first upper depressions, the second upper depressions, the upper projections, the first lower projections, respectively corresponding to the upper flat surface, and the second lower projections A lower mold and a lower mold each having a lower flat surface formed thereon; The preliminary mold apparatus for press forming the preform of the cornerpiece membrane for liquefied natural gas storage tank, the height of the first upper depression and the first lower projection is lower than the height of the small wrinkle portion of the cornerpiece membrane. The preliminary mold apparatus according to claim 6 or 7, The first pre-wrinkle portion and the second pre-wrinkle portion of the preform molded by the pre-mold apparatus is molded into a first wrinkle portion and a second wrinkle portion, wherein at least one of the first pre-wrinkle portion to be molded into a small wrinkle portion And a main mold apparatus having a female mold and a male mold having a shape corresponding to the small wrinkle portion, the apparatus for forming a cornerpiece membrane for a liquefied natural gas storage tank.

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