JP2018069263A - Press working condition determination method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of reducing a labor required for determining a press working condition for performing a press work of a plate into a bent plate.SOLUTION: A press working condition determination method includes a step S101 for selecting a plurality of candidate molds, a step S102 for determining a post-press work shape of a plate obtained by performing a press work of the plate on a plurality of positions by using candidate molds, and a step S103 for comparing the post-press work shape with a target shape of the bent plate relative to respective candidate molds, to thereby determine a mold used for manufacturing the bent plate from among the plurality of candidate molds.SELECTED DRAWING: Figure 5

Description

  The present disclosure relates to a method for determining pressing conditions for pressing a plate into a curved plate.

  In order to press a plate into a curved plate using a die, it is necessary to determine the die to be used and the pressing conditions such as a load condition at the time of pressing. Conventionally, these conditions are determined by repeating trial and error based on the experience and intuition of skilled technicians. Therefore, it took a long time until the press working conditions were finally determined.

  In the mold design support method disclosed in Patent Document 1 below, one mold CAD data is designed based on a reference design shape of a plastic work product designed in advance. Then, based on the FEM model for the mold CAD data and predetermined molding conditions for the plastic workpiece, the molding shape of the plastic workpiece after press working is calculated by simulation. Then, the calculated molded shape of the plastic workpiece is compared with the reference design shape of the plastic workpiece, and its dimensional accuracy is evaluated. As a result, when the dimensional accuracy defect of the plastic workpiece is excessive, the FEM model is corrected and the above-described simulation is performed again.

JP 2005-266892 A

  In the mold design support system described in Patent Document 1, there is only one mold CAD data to be designed and its FEM model. Therefore, as long as the calculated dimensional accuracy defect of the molded shape of the plastic workpiece is excessive, the FEM model correction, simulation, and evaluation of the dimensional accuracy of the molded shape of the plastic workpiece are repeatedly performed. For this reason, it may take a long time to determine the mold design. In particular, when complicated processing is required such that pressing is performed using a single mold at a plurality of positions on the plate, a mold whose dimensional accuracy is within an allowable range at all of the plurality of positions on the plate is finally obtained. It can take a lot of effort to make a decision.

  In view of the above problems, some embodiments according to the present invention have an object to provide a method capable of reducing the labor required to determine the pressing conditions for pressing a plate into a curved plate. To do.

(1) A press working condition determination method according to some embodiments of the present invention includes:
A method of determining pressing conditions for pressing a plate into a curved plate,
Selecting multiple candidate molds;
For each of the candidate molds, obtaining a post-pressing shape of the plate obtained by pressing the plate at a plurality of positions using the candidate mold;
Comparing the post-pressing shape of each of the candidate dies with the target shape of the curved plate, and determining a die to be used when manufacturing the curved plate from among the plurality of candidate dies And.

  According to the method of (1), the post-pressing shape is obtained for each of the plurality of candidate dies, and the die is determined by comparing the post-pressing shape with the target shape of the curved plate. An appropriate mold can be determined from a plurality of candidate molds without repeating the step of selecting a candidate mold. Therefore, even when pressing is performed at a plurality of positions using one mold, the labor required for determining the pressing conditions can be reduced.

(2) In an exemplary embodiment, in the method of (1) above, in the step of selecting the plurality of candidate molds, at least one of the candidate molds includes at least the target shape of the curved plate and the It is selected based on the spring back generated in the plate when the plate is pressed.

  According to the above method (2), at least one of the candidate dies is selected based on a shape obtained by adding a springback to the target shape of the curved plate, and thus the shape after press working obtained by the candidate dies is It is close to the target shape of the curved plate. Therefore, if a mold is determined from these candidate molds by the method described in (1) above, a mold suitable for obtaining the target shape of the curved plate can be determined.

σ_Ｙ：前記板の降伏応力、Ｅ：前記板のヤング率、ｂ：板幅、ｔ：板厚、ν：前記板のポアソン比、Ｒ_ｓ０：第２方向の曲がりのみを拘束した状態での前記板の第１方向曲率半径、ｒ_ｓ０：第１方向の曲がりのみを拘束した状態での前記板の第２方向曲率半径 (3) In an exemplary embodiment, in the configuration of the above (1) or (2), the pressing is performed by moving the mold relative to the plate in the first direction. Performed at multiple locations in one direction,
The target shape of the curved plate has a first plate curvature radius R _s in the first direction and a second plate curvature radius r _s in a second direction orthogonal to the first direction,
At least one of the candidate molds has a first mold curvature radius R ₀ and a second mold curvature radius r that satisfy the following formulas (I) to (IV) in the first direction and the second direction, respectively. _{It has 0} .

σ _Y : Yield stress of the plate, E: Young's modulus of the plate, b: Plate width, t: Plate thickness, ν: Poisson's ratio of the plate, R _s0 : In a state where only bending in the second direction is constrained First direction radius of curvature of the plate, r _s0 : Second direction radius of curvature of the plate in a state where only the bending in the first direction is constrained.

  According to the method of (3) above, at least one of the candidate dies is selected so as to satisfy the above formulas (I) to (IV), so that the shape after press working obtained by each candidate dies is a curved plate This is close to the target shape. Therefore, if a die is determined from these candidate dies by the method described in (1) above, a die suitable for obtaining the target shape of the curved plate is determined in consideration of the springback. be able to.

(4) In an exemplary embodiment, in any one of the methods (1) to (3), in the step of obtaining the post-pressing shape, the plate is pressed using the candidate mold. The load condition at the time is the same at each of the plurality of positions.

  According to the above method (4), the load condition when the plate is pressed using the candidate mold is made the same at all the pressing positions regardless of the shape of the curved plate. As a result, it is easier to compare the shapes after pressing with each candidate mold than to change the load conditions according to the pressing position for each candidate mold, and the labor required to determine the mold is reduced. Can be reduced.

(5) In an exemplary embodiment, in any one of the above methods (1) to (4), the press load condition at each position where the plate is pressed using the mold is optimized. The method further comprises the step of:

  According to the above method (5), the press load condition at each position where the press working is performed is optimized for the die determined from the plurality of candidate dies. As a result, by using a press load condition suitable for a die determined from a plurality of candidate dies, the shape of the curved plate can be made closer to the target shape by pressing.

(6) In an exemplary embodiment, in the method of (5) above, in the step of optimizing the press load condition, after determining the mold, a plurality of types of press load conditions using the mold are determined. Based on the comparison result between the shape of the curved plate obtained by pressing the plate and the target shape, an optimal press load condition is selected from the plurality of types of press load conditions. .

  According to the above method (6), after the mold is determined, the optimum press load condition is selected from a plurality of types of press load conditions for the mold. Therefore, selection of the optimum press load condition (optimization operation of the press load condition) is only required once, and the labor for determining the press work condition for pressing the plate into the curved plate can be reduced.

(7) In an exemplary embodiment, in the method of (5), in the step of obtaining the post-pressing shape,
For each of the candidate molds, based on the comparison result between the shape of the curved plate obtained by pressing the plate with respect to a plurality of types of press load conditions using the candidate mold and the target shape, Select the optimal press load condition from the various press load conditions,
For each of the candidate dies, obtain the post-pressing shape of the plate obtained by pressing under the optimal press load conditions corresponding to the candidate dies,
In the step of optimizing the press load condition, the optimum press load condition corresponding to the mold selected from the plurality of candidate molds is obtained in the step of determining the mold.

  According to the method of (7) above, for each die candidate, the post-pressing shape obtained under the optimum press load condition using the die candidate is obtained and compared. Therefore, it can be said that the compared post-press shapes are generally the best curved plate shapes that can actually be obtained using the respective mold candidates. Therefore, it is possible to determine a more optimal mold for obtaining the target shape of the curved plate. Moreover, the press load condition corresponding to the said metal mold | die can also be obtained at the time of determination of a metal mold | die.

(8) In an exemplary embodiment, in the method of any one of the above (5) to (7), in the step of optimizing the press load condition, the mold and the plate are respectively set to the same scale. The optimum pressing load condition at each position of the plate is obtained by a small-scale test using a test die and a test plate reduced in step (1).

  According to the above method (8), by performing a small scale test, it is possible to obtain an optimum press load condition more easily than a test using an actual mold and an actual plate.

(9) In an exemplary embodiment, in the method of any one of the above (5) to (7), in the step of optimizing the press load condition, each of the plates is performed by simulation using a computer. It is characterized in that an optimum press load condition at the position is obtained.

  According to the method of (9) above, by performing a simulation using a computer, it is possible to obtain an optimum press load condition more easily than a test using an actual mold and an actual plate.

(10) In an exemplary embodiment, in any one of the above methods (1) to (9), in the step of obtaining the post-pressing shape, the plurality of candidate dies and the plate are respectively identical. The post-pressing shape of the plate is obtained by a small scale test using a plurality of test candidate molds and a test plate reduced in scale.

  According to the above method (10), by performing a small scale test, the post-pressing shape of the plate can be obtained more easily than the test using the actual mold and the actual plate.

(11) In an exemplary embodiment, in any one of the methods (1) to (9),
In the step of obtaining the post-pressing shape, the post-pressing shape of the plate is obtained by a simulation using a computer.

  According to the above method (11), by performing a simulation using a computer, the post-pressing shape of the plate can be obtained more easily than the test using the actual mold and the actual plate.

(12) In an exemplary embodiment, in any one of the above methods (1) to (11), the pressing process moves the mold relative to the plate in the first direction. Performed at a plurality of positions in the first direction,
The target shape of the curved plate has a first plate curvature radius R _s in the first direction and a second plate curvature radius r _s in a second direction orthogonal to the first direction,
It said second plate a radius of curvature r _s is characterized by changes in accordance with the position in the first direction.

In the methods (1) to (11), as described above, the post-pressing shape is obtained for each of the plurality of candidate dies, and the die is determined by comparing the post-pressing shape with the target shape of the curved plate. As a result, the labor required to determine the press working conditions can be reduced. Therefore, as in the above (12), if the radius of curvature r _s of the second direction to perform press working at a plurality of positions in the first direction in order to obtain a curved plate that varies in response to the first direction of the position Even so, it is possible to determine the press working conditions with less effort.

(13) In an exemplary embodiment, in any one of the above methods (1) to (12), the curved plate constitutes a part of a shell of a non-spherical tank of an LNG carrier. And

  As described above, since it is possible to reduce the labor required for determining the press working conditions by the methods (1) to (11), as described in the above (13), one of the shells of the non-spherical tank of the LNG carrier ship. Even when the curved plate having a complicated shape constituting the portion is obtained by press working, the press working conditions can be appropriately determined.

  According to some embodiments of the present invention, it is possible to reduce the labor required to determine the pressing conditions for pressing a plate into a curved plate.

It is a figure which shows the structural example of the non-spherical tank of an LNG tank carrier. It is a figure which shows the structural example of the curved board which comprises the non-spherical tank of an LNG tank carrier. It is a figure which shows the metal mold | die of the press work which concerns on some embodiment of this invention. It is a figure which shows the press work or press work test which concerns on some embodiment of this invention. It is a flowchart which shows the flow of the press work condition determination which concerns on some embodiment of this invention. It is a figure which shows the target shape of the curved plate which concerns on some embodiment of this invention, and the shape after a press process about a candidate metal mold | die. It is a flowchart which shows the flow of the press work condition determination which concerns on another embodiment of this invention. It is a flowchart which shows the flow of the press work condition determination which concerns on another embodiment of this invention.

(First embodiment)
Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative examples. Absent.
For example, an expression indicating that things such as “identical”, “equal”, and “homogeneous” are in an equal state not only represents an exactly equal state, but also has a tolerance or a difference that can provide the same function. It also represents the existing state. On the other hand, the expressions “comprising”, “comprising”, “comprising”, “including”, or “having” one constituent element are not exclusive expressions for excluding the existence of the other constituent elements.

  Hereinafter, first, before describing the press working condition determination method according to some embodiments, as an example of a press working object to which some embodiments according to the present invention are applied, an LNG carrier The curved plate constituting the non-spherical tank will be described with reference to FIGS. 1 and 2. Then, the press work used as the application object of some embodiment which concerns on this invention is demonstrated using FIG.3 and FIG.4. And the content of the processing condition determination method which concerns on some embodiment of this invention is demonstrated using FIGS. 3-6, The processing condition determination method which concerns on another embodiment is demonstrated using FIG. A processing condition determination method according to another embodiment will be described with reference to FIG.

The press work to which some embodiments according to the present invention are applied is used, for example, for manufacturing a curved plate constituting a non-spherical tank of an LNG carrier.
FIG. 1 is a diagram illustrating an example of a non-spherical tank of an LNG carrier. As shown in FIG. 1, the shell forming the non-spherical tank 1 of the LNG tank carrier ship has a plurality of sections (3a to 3c, 5a, 5b, 7) arranged along the y direction (first direction). It may be formed by bonding. In the exemplary embodiment shown in FIG. 1, the non-spherical tank 1 includes a first spherical shell portion in order from one side (upper side on the paper surface) of the tank 1 to the other side (lower side on the paper surface). 3a, the second annular portion 5a, the cylindrical portion 7, the second spherical shell portion 3b, the second annular portion 5b, and the third spherical shell portion 3c are arranged.

  Each of the plurality of sections (3a to 3c, 5a, 5b, 7) constituting the non-spherical tank 1 may be formed by joining a plurality of curved plates by welding or the like. At this time, each of the sections (3a to 3c, 5a, 5b, 7) may be configured by joining a plurality of curved plates arranged in the x direction (second direction).

Here, a specific example of the curved plate constituting each section of the non-spherical tank 1 will be described.
2A is a plan view showing a curved plate according to an embodiment, and FIG. 2B is a cross-sectional view taken along the x direction of the curved plate shown in FIG. ) Is a cross-sectional view taken along the y direction of the curved plate shown in FIG.
In the exemplary embodiment shown in FIGS. 2A and 2B, each curved plate 9 has a shape whose longitudinal direction is the y direction. That is, the length of the curved plate 9 in the y direction is larger than the width in the x direction. In this case, even if each section (3a-3c, 5a, 5b, 7) of the non-true tank 1 is constituted by joining a plurality of curved plates 9 arranged in the x direction (second direction) to each other. Good.
In the example shown in FIG. 2, the curved plate 9, over the y-direction entire area has a radius of curvature r _s in cross section along the x-direction (second direction) (see FIG. 2 (b)), the y-direction It has a radius of curvature R _s in the cross section along (first direction) (see FIG. 2C).

The overall shape of each of the plurality of sections (3a to 3c, 5a, 5b, 7) constituting the non-spherical tank 1 is determined by the shape of the curved plate 9 constituting the section.
In the example of the non-true spherical tank 1 shown in FIG. 1, the curved plates 9 constituting the spherical shell portions 3a, 3b and 3c have the same radius of curvature in the x direction and the y direction (r _s = R _s ). Further, the curved plates 9 constituting the annular portions 5a and 5b have different radii of curvature in the x and y directions (r _s ≠ R _s ), and the curvature radius r _{s of} the curved plate 9 in the x direction is the y direction. It changes according to the position. The curved plate 9 constituting the cylindrical portion 7 has the same radius of curvature in the x direction (r _s is constant regardless of the position in the y direction), and has no curvature in the y direction (R _s = ∞). .

  In addition, as another example of the target object of the press processing to which some embodiments of the present invention are applied, there are a true spherical tank of an LNG carrier and an LNG tank on land. Since these tanks are true spheres, their shapes are all constituted by spherical shells. Therefore, the curved plates constituting these tanks have a shape having the same radius of curvature in the x direction and the y direction.

  The curved plate 9 as described above is manufactured by press working as an application target of some embodiments according to the present invention. Hereinafter, the case where this press work is used for manufacture of the curved board 9 which comprises the annular parts 5a and 5b of the non-spherical tank 1 of the LNG tank carrier will be described. However, this pressing can also be applied to the other curved plates described above.

FIG. 3 is a diagram showing a mold used for press working.
As shown in the figure, a mold 21 used for press working is composed of a male mold 21a and a female mold 21b. In order to obtain the curved plate 9 described above, press working using the mold 21 is performed at a plurality of positions on a plate made of, for example, an aluminum alloy, which is a workpiece.

In FIG. 3, the press working surface of the male die 21a is formed in a curved shape that curves in a convex shape. On the other hand, the press working surface of the female die 21b on which the plate 19 is placed is formed in a curved shape that curves in a concave shape. The curved shape of the press-worked surfaces of the male mold 21 a and the female mold 21 b has a shape along the curved shape of the curved plate 9. That is, the curved plates 9 constituting the annular portions 5a and 5b of the non-spherical tank 1 of the LNG tank carrier ship have different radii of curvature in the x direction and the y direction, respectively. Therefore, the curved shapes of the press surfaces of the male mold 21a and the female mold 21b for manufacturing the curved plate 9 have different radii of curvature in the x direction and the y direction, respectively.
When the plate 19 is pressed, the drive unit 23 shown in FIG. 3 operates to press the male mold 21a against the female mold 21b. This drive part 23 may be comprised by the hydraulic cylinder etc., for example.

FIG. 4 is a diagram illustrating a state in which pressing using the mold 21 is performed at a plurality of positions.
Referring to FIG. 4, the width in the x direction on the pressing surface of the male mold 21 a and the female mold 21 b is substantially equal to the width of the plate 19 in the x direction. The width in the y direction on the press-worked surfaces of the male mold 21a and the female mold 21b is smaller than the y direction width of the plate 19. Therefore, when the plate 19 is pressed, the plate 19 is placed on the female die 21b. And while this board 19 is moved relatively with respect to the male metal mold | die 21a and the female metal mold | die 21b in ay direction, in several press positions 50 (1) -50 (n) of the board 19, a male metal mold | die is carried out. The die 21a is pressed against the female die 21b. Thus, the plate 19 is pressed at a plurality of press positions 50 (1) to 50 (n).

  The radius of curvature of the curved plate 9 in the x direction changes according to the position in the y direction. For this reason, when the curved plate 9 is manufactured by press working, the press load applied to the plate 19 by the male die 21 is the target of the curved plate 9 at a plurality of press positions 50 (1) to 50 (n) of the plate 19. It is set to change according to the shape. Thereby, the curved plate 9 in which the radius of curvature in the x direction changes according to the position in the y direction is obtained.

Note that a candidate mold 31, a test candidate mold 41, and a load condition determination candidate mold 51, which will be described later, also have the same configuration as the mold 21.
Therefore, in FIGS. 3 and 4, these dies 31, 41, 51 are also the dies of the respective dies (31, 41, 51) with a suffix added to each symbol. And a symbol with b at the end of each symbol is shown as a female die of each die (31, 41, 51).

Next, the contents of the press working condition determination method according to some embodiments of the present invention will be described with reference to the flowchart of FIG.
FIG. 5 is a flowchart showing a flow of determining press working conditions according to some embodiments of the present invention. As described above, the object to be pressed is the curved plate 9 constituting the annular portions 5a and 5b of the non-spherical tank 1 of the LNG tank carrier. However, this press working condition determination method can also be applied to press working of other curved plates described above.

  Referring to the flow diagram of FIG. 5, in this press working condition determination method, step S101 for selecting a plurality of candidate dies 31 and a plurality of plates 19 using the candidate dies 31 for each candidate dies 31 are provided. Step S102 for determining the post-pressing shape of the plate obtained by pressing at the position of the step, and comparing the post-pressing shape for each candidate die 31 with the target shape of the curved plate 9, a plurality of candidate gold Step S103 for determining the mold 21 to be used when manufacturing the curved plate 9 from the mold 31, and Step S104 for optimizing the press load condition at each position where the plate is pressed using the mold 21. Is provided. Hereinafter, each step will be described in detail.

  In step S101 for selecting a plurality of candidate dies 31, a plurality of candidate dies 31 including male candidate dies 31a and female candidate dies 31b as shown in FIG. 3 are selected. In S <b> 103 to be described later, the most suitable candidate mold 31 for manufacturing the curved plate 9 among the plurality of candidate molds 31 is determined as the mold 21 for manufacturing the actual curved plate 9.

  At least one of the plurality of candidate molds 31 is determined by taking into account the springback generated in the plate 19 when the plate 19 is pressed with respect to the target shape of the curved plate 9. That is, after the plate 19 is pressed by the male die 21a and the female die 21b, when the male die 21a is separated from the plate 19 and the female die 21b, the curvature radius of the plate 19 is set to be the male die 21a and the female die 21b. The radius of curvature at the time of being pressed is changed so as to return somewhat to the radius of curvature before the press. Therefore, at least one of the candidate dies 31 is determined so that the post-pressing shape of the plate 19 after the change in the curvature radius becomes the target shape of the curved plate 9.

σ_Ｙ：板１９の降伏応力、Ｅ：板１９のヤング率、ｂ：板１９のｘ方向の幅、ｔ：板厚、ν：板１９のポアソン比、Ｒ_ｓ０：ｘ方向の曲がりのみを拘束した状態での板１９の第１方向（ｙ方向）曲率半径、ｒ_ｓ０：ｙ方向の曲がりのみを拘束した状態での板１９のｘ方向における第２方向曲率半径 The shape of the candidate mold 31 in consideration of the spring back described above can be obtained as follows. That is, pressing is performed at a plurality of positions in the y direction by moving the mold 21 relative to the plate 19 in the y direction (first direction), and the target shape of the curved plate 9 is y When having the first plate curvature radius R _s in the direction and the second plate curvature radius r _s in the x direction orthogonal to the y direction, the first mold curvature radii R ₀ and x in the y direction of the candidate mold 31 the second mold curvature radius _{r 0} in the direction is calculated by the following (I) ~ (IV).

σ _Y : yield stress of the plate 19, E: Young's modulus of the plate 19, b: width of the plate 19 in the x direction, t: plate thickness, ν: Poisson's ratio of the plate 19, R _s0 : constraining only the bending in the x direction Radius of curvature in the first direction (y direction) of the plate 19 in the bent state, r _s0 : second direction curvature radius in the x direction of the plate 19 in a state where only the bending in the y direction is constrained

Here, as shown in FIG. 6, the radius of curvature of the curved plate 9 changes in the x direction (second direction) depending on the position in the y direction (first direction). In this case, the r _s of the target shape at the representative position in the y direction of the bending plate 9 may be substituted into the above formula (I) ~ (IV). For example, in the target shape of the curved plate 9, the y-direction position of the curved plate 9 (hereinafter referred to as “average y-direction position”) that represents the average curvature radius of the maximum curvature radius and the minimum curvature radius in the x direction is representative. used as the position, the r _s of the target shape in the average y position may be substituted into the above formula (I) ~ (IV).

Further, the plurality of candidate molds 31 obtained as described above are obtained by using the expressions (I) to (IV) above and the representative position (for example, the average y-direction position) of the curved plate 9. the r _s of the target shape in another y position may be obtained by substituting the above formula (I) ~ (IV) is. Also, several other candidate mold 31, for example, the shape close to a candidate mold 31 of obtaining the r _s of the target shape at the representative position is substituted into the above formula (I) ~ (IV), heuristics, etc. May be selected randomly based on.

In the above-described method, the first mold radius of curvature R ₀ and the second mold radius of curvature r ₀ of at least one candidate mold 31 are obtained by the above formulas (I) to (IV). For example, based on the springback rate of the plate 19, even if at least one candidate mold 31 is determined so that the shape of the plate 19 after the springback occurs becomes the target shape of the curved plate 9. Good. In this method, the value of the radius of curvature in the y direction and the value of the radius of curvature in the x direction are the same as the curved plate 9 constituting the spherical shell portions 3a, 3b and 3c of the non-spherical tank 1 of the LNG carrier described above. It can be preferably used in the case of.

  Subsequently, in step S102 for obtaining a post-pressing shape, for each candidate die 31 selected above, the plate 19 obtained by pressing the plate 19 at a plurality of positions using the candidate die 31 is used. A shape after pressing is required. In this embodiment, the plate 19 is pressed by a small scale test using a plurality of test candidate dies 41 and a test plate 49 in which the plurality of candidate dies 31 and the plate 19 are made smaller on the same scale. A rear shape is required.

  Specifically, as shown in FIG. 4, for each test candidate mold 41, the test plate 49 is relative to the male test candidate mold 41a and the female test candidate mold 41b in the y direction. In the press position of the test plate 49 corresponding to the plurality of press positions 50 (1) to 50 (n) of the plate 19, the female test candidate die 41b is moved by the male test candidate die 41a. Pressed against. By doing so, a plurality of test plates 49 pressed by the respective test candidate dies 41 are formed.

  At this time, the press load conditions when the test plate 49 is pressed using the test candidate mold 41 are the same at a plurality of press positions of the test plate 49. The press load condition can be a press load condition that is expected to be appropriate at the above-described representative position (for example, the average y-direction position). Then, the post-pressing shape of the plate 19 for each candidate mold 31 is obtained from the post-pressing shape of each test plate 49. Instead of the above-described small scale test, the post-pressing shape of the plate 19 for each candidate mold 31 may be obtained by an actual scale test.

  Subsequently, in step S103 for determining a mold, the post-pressing shape for each candidate mold 31 obtained in step S102 is compared with the target shape of the curved plate 9, and a plurality of candidate molds 31 are compared. The mold 21 used when manufacturing the curved plate 9 is determined. FIG. 6 is a diagram illustrating the target shape of the curved plate 9 and the post-pressing shapes obtained in step S102 for the candidate die A, candidate die B, and candidate die C, which are the three candidate dies 31. FIG. .

  Referring to FIG. 6, the shape of the candidate mold A is closer to the target shape of the curved plate 9 than the candidate mold B and the candidate mold C which are the other candidate molds 31. Therefore, this candidate mold A is determined as the mold 21 used when the curved plate 9 is manufactured. The determination of the mold 21 is, for example, that the difference between the radius of curvature of the candidate mold 31 in the x direction and the target shape of the curved plate 9 is within an allowable range in each candidate mold 31. Candidate mold 31 can be determined.

  In addition, when there are a plurality of candidate molds 31 in which the above-described difference falls within an allowable range, for example, with respect to the plurality of candidate molds, the curvature radius in the x direction at each y-direction position is the target of the curved plate 9. An amount that is less than the shape may be compared, and the candidate mold 31 that is relatively smaller than the other candidate molds may be preferentially selected. This is because the curved plate 9 made of aluminum alloy that constitutes the non-true tank 1 of the LNG tank carrier may be difficult to correct to increase the radius of curvature after pressing.

  Subsequently, in step S104 for optimizing the press load condition, the press load condition at each y-direction position where the plate 19 is pressed using the mold 21 determined in step S103 is optimized. Specifically, after the mold 21 is determined, the shape of the curved plate 9 obtained by pressing the plate 19 for a plurality of types of press load conditions using the mold 21 and the target shape of the curved plate 9 are determined. Based on the comparison result, an optimum press load condition is selected from a plurality of types of press load conditions.

  In this embodiment, a small-scale test is performed using a load condition determining die 51 and a load condition determining plate 59 in which the determined mold 21 and plate 19 are made smaller by the same scale. As shown in FIG. 4, with respect to the load condition determining die 51, the load condition determining plate 59 is relatively relative to the male load condition determining die 51a and the female load condition determining die 51b in the y direction. While being moved, at the press position of the load condition determining plate 59 corresponding to the plurality of press positions 50 (1) to 50 (n) of the plate 19, the female load condition determining die 51a is used by the male load condition determining die 51a. It is pressed against the mold 51b. By doing so, the load condition determining plate 59 pressed by the load condition determining die 51 is formed. This small scale test is performed on a plurality of load condition determining plates 59 using a plurality of types of press load conditions.

  Then, the post-pressing shape of the plate 19 for the mold 21 using the respective pressing load conditions is obtained from the post-pressing shape of each load condition determining plate 59. Based on the comparison result between each post-pressing shape and the target shape of the curved plate 9, an optimum press load condition is selected from a plurality of types of press load conditions, and this flow is completed. Instead of the above-described small scale test, the post-pressing shape of the plate 19 for each press load condition may be obtained by an actual scale test.

In the present embodiment, the press working conditions are determined as described above. Therefore, in this embodiment, the post-pressing shape is obtained for each of the plurality of candidate dies 31 in step S101, and the die 21 is determined by comparing the post-pressing shape with the target shape of the curved plate 9 in step S102. Thus, an appropriate mold 21 can be determined from the plurality of candidate molds 31 without repeatedly performing the step of selecting the candidate mold 31. Therefore, even when pressing is performed at a plurality of positions in the y direction using one mold 21 as in the present embodiment, the labor required to determine the pressing conditions can be reduced.
Thus, for example, even in the case of performing the press working in multiple y-direction position to the radius of curvature r _s of the x-direction to obtain a curved plate 9 that varies depending on the position in the y direction, with less effort Pressing conditions can be determined. Similarly, for example, even when the curved plate 9 having a complicated shape constituting a part of the shell of a non-spherical tank of an LNG carrier is obtained by press processing, the press processing conditions can be appropriately determined.

  In the present embodiment, at least one of the plurality of candidate dies 31 is selected based on the shape obtained by adding the springback to the target shape of the curved plate 9 in step S101, and thus obtained by each candidate dies 31. The post-pressing shape is close to the target shape of the curved plate 9. Therefore, if the die 21 is determined from the plurality of candidate dies 31 using the method for determining press working conditions according to the present embodiment, the die 21 suitable for obtaining the target shape of the curved plate 9 is obtained. Can be determined.

Moreover, in this embodiment, since at least one of the candidate dies 31 is selected so as to satisfy the above formulas (I) to (IV) in step S101, the post-pressing shape obtained by each candidate dies 31 is This is close to the target shape of the curved plate 9. Therefore, if the die 21 is determined from the plurality of candidate dies 31 by the method for determining the press working condition according to the present embodiment, the die 21 suitable for obtaining the target shape of the curved plate 9 is determined. be able to. Incidentally, the above formula (I) ~ (IV) is, if the target shape of the curved plate 9 is a complicated curved shape as the second direction of curvature radius r _s depending on the position in the first direction changes Can be suitably used. Therefore, if at least one candidate mold 31 satisfying the above formulas (I) to (IV) is selected, the above-described complicated target is selected from the plurality of candidate molds 31 including the candidate mold 31. A mold 21 suitable for manufacturing the curved plate 9 having a shape can be determined.

  Further, in this embodiment, the load condition when pressing the plate 19 using the candidate mold 31 in the step of S102 is the y-direction position where the plate 19 is pressed regardless of the shape of the curved plate 9 or the like. In the same way. As a result, it becomes easier to compare the shapes after pressing by each candidate die 31 than to change the load condition for each candidate die 31 in accordance with the position in the y direction. The labor required can be reduced.

  In the present embodiment, after the mold 21 is determined in step S103, an optimal press load condition is selected from a plurality of types of press load conditions for the mold 21 in step 104. Therefore, selection of the optimum press load condition (optimization work of the press load condition) is only required once, and the labor for determining the press work condition for pressing the plate 19 into the curved plate 21 can be reduced.

  Further, in the present embodiment, in order to obtain an optimum press load condition at each y-direction position of the plate 19 by performing a small scale test in Step 104, the actual mold 21 and the actual plate 19 are Optimal press load conditions can be obtained more easily than the test used.

  In this embodiment, since the small scale test is performed in step 102 to obtain the post-pressing shape of the plate 19, it is simpler than the test using the actual mold 21 and the actual plate 19. The post-pressing shape of the plate 19 can be obtained.

(Second Embodiment)
An embodiment different from the first embodiment will be described with reference to FIG. In the following description, the same reference numerals are given to portions having the same configuration as that of the first embodiment, and redundant description is omitted. The difference between the press load condition determination method according to the present embodiment and the first embodiment is that a computer is used in Step 202 and Step S204 instead of the small scale test according to Step S102 and Step S104 of the first embodiment. It is a point to perform simulation.

  As shown in FIG. 7, in step S <b> 202 for obtaining a shape after press working, for each candidate die 31 selected in step S <b> 101 for selecting a plurality of candidate dies 31, a plate is formed using these candidate dies 31. The post-pressing shape of the plate 19 obtained by pressing 19 at a plurality of y-direction positions is obtained by simulation (for example, FEM) using a computer.

  Further, as shown in FIG. 7, in step S204 for optimizing the press load condition, after the mold 21 is determined in step S103, the plate 19 is pressed for a plurality of types of press load conditions using the mold 21. The shape of the curved plate 9 obtained as described above is obtained by simulation (for example, FEM) using a computer. Then, based on the comparison result between this shape and the target shape of the curved plate 9, an optimal press load condition is selected from a plurality of types of press load conditions.

  In this embodiment, in order to obtain the post-pressing shape of the plate 19 by performing a simulation using a computer in step 202, the test of the plate 19 is performed by a test using the actual mold 21 and the actual plate 19. The post-pressing shape of the plate can be easily determined rather than the post-pressing shape.

  Further, in the present embodiment, in step 204, a simulation using a computer is performed to obtain an optimum press load condition at each y-direction position of the plate 19, so that the actual mold 21 and the actual plate 19 are obtained. It is possible to obtain the optimum press load condition more easily than the test using.

In another embodiment, step S102 described in FIG. 5 may be performed instead of step S202. That is, when the post-pressing shape is obtained, the plate 19 is pressed by a small-scale test using the test candidate die 41 and the test plate 49 for each candidate die 31 selected in step S101. The rear shape may be obtained. Thereafter, step S103 and step S204 shown in FIG. 7 are performed to determine the die 21 and calculate the optimum press load condition corresponding to the die 21.
In still another embodiment, step S104 described in FIG. 5 may be performed instead of step S204. That is, after performing steps S101, S202, and S103 in FIG. 7, a small-scale test using the load condition determining mold 51 and the load condition determining plate 59 is performed, so that the optimum for the mold 21 is obtained. The press load condition may be obtained.

(Third embodiment)
An embodiment different from the first embodiment and the second embodiment will be described with reference to FIG. In the following description, parts having the same configurations as those in the first embodiment and the second embodiment are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 8, in the present embodiment, the step of obtaining the post-pressing shape obtains the post-pressing shape for each of a plurality of types of press load conditions for each of the candidate dies 31 shown in FIGS. 3 and 4. Step S302 is included.

  In step S302, for each candidate die 31 selected in step S101, the shape of the curved plate obtained by pressing each y-direction position where the plate 19 is pressed under a plurality of types of press load conditions is obtained. Desired.

  In addition, the shape of the curved plate 9 obtained after press working for a plurality of types of press load conditions is such that the test candidate mold 41 and the test plate 49 in which the candidate mold 31 and the plate 19 are made smaller on the same scale, respectively. It can be obtained by performing a small scale test using and. Further, the shape of the curved plate 9 obtained after press working for a plurality of types of press load conditions can also be obtained by simulation (for example, FEM) using a computer. Alternatively, it may be obtained by a test using an actual scale candidate mold 31 and the plate 19.

Subsequently, in step S303, the post-pressing shape of the plate 19 obtained for each of the plurality of types of press load conditions for each candidate die 31 in step S302 is compared with the target shape of the curved plate 9. Based on the comparison result, the die 21 used when the curved plate 9 is manufactured from the plurality of candidate dies 31 and the optimum press load condition corresponding thereto are determined.
In step S303, after obtaining the optimum press load condition for each candidate die 31 to obtain the post-pressing shape closest to the target shape of the curved plate 9, each candidate die is obtained under the optimum press load condition. The candidate die 31 closest to the target shape of the curved plate 9 among the post-press shapes obtained by 31 may be adopted as the die 21.

  The determination of the mold 21 is, for example, within the allowable range of the difference between the radius of curvature of the candidate mold 31 in the x direction and the target shape of the curved plate 9 at each y position in the candidate molds 31. The candidate mold 31 can be determined. In addition, when there are a plurality of candidate molds 31 in which the above-described difference falls within an allowable range, for example, with respect to the plurality of candidate molds, the curvature radius in the x direction at each y-direction position is the target of the curved plate 9. An amount that is less than the shape may be compared, and the candidate mold 31 that is relatively smaller than the other candidate molds may be preferentially selected.

  According to the present embodiment, for each die candidate 31, the post-pressing shape obtained by the optimum press load condition using this die candidate 31 is obtained and compared. Therefore, it can be said that the compared post-pressing shapes are generally the best shapes of the curved plates 9 that can be actually obtained using the respective mold candidates 31. Therefore, a more optimal mold 21 can be determined to obtain the target shape of the curved plate 9. Moreover, the press load conditions corresponding to the mold 21 can be obtained together with the determination of the mold.

DESCRIPTION OF SYMBOLS 1 Tank 3a, 3b, 3c Spherical shell part 5a, 5b, 5c Ring part 7 Cylindrical part 9 Curved plate 21 Mold 21a Male mold 21b Female mold 23 Drive part 31 Candidate mold 31a Male candidate mold 31b Female candidate Mold 41 Test candidate mold 41a Male test candidate mold 41b Female test candidate mold 51 Load condition determining mold 51a Male load condition determining candidate mold 51b Female load condition determining candidate mold

Claims (13)

A method of determining pressing conditions for pressing a plate into a curved plate,
Selecting multiple candidate molds;
For each of the candidate molds, obtaining a post-pressing shape of the plate obtained by pressing the plate at a plurality of positions using the candidate mold;
Comparing the post-pressing shape of each of the candidate dies with the target shape of the curved plate, and determining a die to be used when manufacturing the curved plate from among the plurality of candidate dies When,
A press working condition determining method comprising:   In the step of selecting the plurality of candidate dies, the candidate dies are selected based on at least the target shape of the curved plate and a spring back generated in the plate when the plate is pressed. The press working condition determination method according to claim 1, wherein the press working condition is determined. The pressing is performed at a plurality of positions in the first direction by moving the mold relative to the plate in the first direction,
The target shape of the curved plate has a first plate curvature radius R _s in the first direction and a second plate curvature radius r _s in a second direction orthogonal to the first direction,
At least one of the candidate molds has a first mold curvature radius R ₀ and a second mold curvature radius r that satisfy the following formulas (I) to (IV) in the first direction and the second direction, respectively. The press working condition determination method according to claim 1, wherein the press working condition determination method has _zero .

σ _Y : Yield stress of the plate, E: Young's modulus of the plate, b: Plate width, t: Plate thickness, ν: Poisson's ratio of the plate, R _s0 : In a state where only bending in the second direction is constrained First direction radius of curvature of the plate, r _s0 : Second direction radius of curvature of the plate in a state where only the bending in the first direction is constrained.   2. The step of obtaining the post-pressing shape, wherein a load condition when the plate is pressed using the candidate mold is the same at each of the plurality of positions. 4. The press working condition determination method according to any one of 3.   The press work according to any one of claims 1 to 4, further comprising a step of optimizing a press load condition at each position where the press of the plate using the mold is performed. Condition determination method.   In the step of optimizing the press load condition, after determining the mold, the shape of the curved plate and the target shape obtained by pressing the plate for a plurality of types of press load conditions using the mold The press working condition determination method according to claim 5, wherein an optimum press load condition is selected from the plurality of types of press load conditions based on a comparison result with. In the step of obtaining the post-press shape,
For each of the candidate molds, based on the comparison result between the shape of the curved plate obtained by pressing the plate with respect to a plurality of types of press load conditions using the candidate mold and the target shape, Select the optimal press load condition from the various press load conditions,
For each of the candidate dies, obtain the post-pressing shape of the plate obtained by pressing under the optimal press load conditions corresponding to the candidate dies,
The step of optimizing the press load condition obtains the optimum press load condition corresponding to the mold selected from the plurality of candidate molds in the step of determining the mold. 5. The press working condition determination method according to 5.   In the step of optimizing the press load condition, each position of the plate is measured by a small-scale test using a test die and a test plate in which the die and the plate are made smaller on the same scale. The press working condition determination method according to any one of claims 5 to 7, wherein an optimum press load condition is determined.   8. The step of optimizing the press load condition obtains an optimal press load condition at each of the positions of the plate by a simulation using a computer. The press working condition determination method as described in 2.   In the step of obtaining the post-pressing shape, the plate is obtained by a small scale test using a plurality of candidate test dies and a test plate obtained by reducing the plurality of candidate dies and the plate on the same scale. The press working condition determination method according to any one of claims 1 to 9, wherein a shape after the press working is obtained.   The press working condition according to any one of claims 1 to 9, wherein, in the step of obtaining the post-pressing shape, the post-pressing shape of the plate is obtained by a simulation using a computer. Decision method. The pressing is performed at a plurality of positions in the first direction by moving the mold relative to the plate in the first direction,
The target shape of the curved plate has a first plate curvature radius R _s in the first direction and a second plate curvature radius r _s in a second direction orthogonal to the first direction,
It said second plate a radius of curvature r _s is pressing condition determining method according to any one of claims 1 to 11, characterized in that changes in accordance with the position in the first direction.   The press working condition determination method according to any one of claims 1 to 12, wherein the curved plate constitutes a part of a shell of a non-spherical tank of an LNG carrier.

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