JP3778305B2 - Curved board splitting method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a curved surface splitting method for determining the size of a flat plate before bending when the curved surface is formed by bending a plurality of flat plates.
[0002]
[Prior art]
The shape of the hull is streamlined to reduce water resistance, and in particular, the bow and stern portions have complex curved surfaces. The outer plate constituting the curved surface of the hull is manufactured by bending a large number of appropriately sized flat plates into a curved plate and joining them by welding.
[0003]
[Problems to be solved by the invention]
In the case of a simple shape such as the center part of the hull, it is not necessary to consider the ease of bending or the like in determining the dimensions of the flat plate used for the outer plate. On the other hand, where the curved surface is complex, such as the bow or stern, the size of the flat plate before being processed into a curved surface is determined to be as large as possible. No matter how complicated the curved surface is, it can be bent easily by bending a small flat plate and splicing it, but there are many seams. At present, the flat plate dimensions to be bent into a complicated curved surface with such a large curvature are determined by the experience of experienced technicians. However, since it is not possible to make a quantitative judgment, it is often difficult to know whether the dimensions of the flat plate determined by the judgment were appropriate, and the number of technicians who can make the judgment is limited, and the successors are not nurtured much. There is a high possibility that such technicians will be gone.
[0004]
The present invention has been made in view of the above-described problems. When a complex curved surface is formed by bending a plurality of flat plates, the curved plate is divided into appropriate dimensions in consideration of bending. It aims to provide a method.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, in order to form a curved surface by bending and joining a plurality of flat plates, in the method of dividing the curved surface, the plane is determined. Calculate the planned strain that occurs when deformed into the planned curved surface shape by the finite element method, determine the linear heating condition for generating the predetermined strain according to the magnitude of the strain, select the heating condition, and In the distribution range, the plate is divided based on a range in which a strain having a magnitude that can be generated under the selected heating condition is distributed.
[0006]
The distortion that occurs when the plane is deformed to the shape of the planned curved surface is referred to as the planned distortion, and this is calculated by the finite element method. If this planned strain is generated in the flat plate, the flat plate is processed into the planned shape. As the bending method, a linear heating method is used in which linear heating is performed to generate shrinkage strain. The linear heating method can determine the magnitude and direction of the strain generated by the heating conditions such as the heating device, the heating time, the heating direction and the heating line density. Therefore, first select the heating conditions when bending by linear heating, determine the size of the strain that can be generated, and within the range of the planned strain distribution, the range of distribution of the strain size generated by the selected heating conditions The size of the plate to be bent under heating conditions is determined based on the size of the plate. Thereby, the dimension of the largest flat plate which can be bent under the selected heating condition can be determined.
[0007]
In the invention of claim 2, the planned strain is calculated based on the strain generated when the planned curved surface shape is deformed into a plane. If the sign of the strain generated when the planned curved surface shape is transformed into a plane is reversed (for example, the tensile strain is a compression strain), the planned strain when the plane is transformed into the planned curved surface shape can be obtained.
[0008]
According to a third aspect of the present invention, the plate division determined based on the distribution state of the planned strain is a plate division corrected based on at least one of the plate division yield and the standard plate size.
[0009]
If the size of the bent plate is determined to be the maximum size that can be bent, the efficiency of the reduction of the plate joint is good, but depending on the shape of the bent plate, there are many surrounding cut-off ranges when cutting from a rectangular material. The yield is worse. In addition, the flat plate has some standard dimensions, and when a dimension other than this standard is purchased, the flat plate becomes expensive. Thus, the dimensions of the flat plate are determined in consideration of conditions other than bending.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram for explaining an embodiment of the present invention. G1 indicates a state in which a flat plate is deformed into a planned curved surface and a strain generated thereby is calculated using a finite element method elastic large deflection calculation method. This strain is called a planned strain, and when this planned strain is generated on a flat plate, it can be bent into a planned curved surface.
[0011]
G2 indicates the distribution state of the planned strain generated on the flat plate. In the finite element method, the calculation target surface is divided into a number of meshes, and the strain and stress are calculated as uniform within the mesh. The arrow → ← in the mesh indicates compression strain. G3 represents the magnitude of strain that can be generated according to the heating conditions used for linear heating, for each of a plurality of heating conditions, and is a criterion for determining the division of a flat plate. The linear heating method is a method of processing an object into a desired curved surface by heating the object in a linear shape, generating compressive strain, and determining and heating the heating conditions such as the heating strength, heating position and direction. The heating intensity is determined by the output of the heating device and the heating time. In the case of dividing a flat plate, the heating conditions for bending the flat plate are selected and determined from judgment criteria, and thereby the magnitude of distortion that can be generated is determined.
[0012]
G4 sets a boundary that limits the range within the strain magnitude determined in G3 from the strain distribution obtained in G2. Splitting is performed as shown by a two-dot chain line including the boundary. The plate division once determined in this way is corrected in consideration of the following two points to determine the final plate division. One of them is to examine whether the yield of this planing is good. The second is an examination of whether or not the board split dimensions are within the standard dimensions for commercial transactions. When these conditions are not met, the heating condition is changed, the strain is changed as the criterion for judgment, the boundary is reset, and the board is divided so as to satisfy the above two conditions. In addition, you may consider conditions other than these two.
[0013]
G5 indicates a method of dividing the remaining curved surface cut by G4. Also for the remaining curved surface, the planned strain when the flat plate is deformed to the remaining curved surface is obtained, and the plate is divided by the same procedure as described in G2 to G4. By dividing the plate in this way, the target curved surface can be divided. When calculating the planned strain, the planned shape may be crushed to a plane, and the sign of the strain generated at that time may be changed (for example, the tensile strain is changed to the compressive strain) as the planned strain.
[0014]
Next, the determination criterion indicated by G3 will be described. In the determination criteria, the magnitude of strain determined by the heating conditions is defined. The relationship between this heating condition and strain will be described. FIG. 2 shows the amount of deformation that occurs at the position of the heating line when a high-frequency induction heater having a predetermined output is used as a heating device and a predetermined length is heated linearly. The horizontal axis indicates the heating duration T, and the vertical axis indicates the deformation amount in the direction perpendicular to the heating line. Curve A indicates in-plane contraction deformation indicating deformation at the center of the plate thickness, and curve B indicates the amount of bending deformation in the upper or lower direction of the plate thickness. The horizontal axis may be a value obtained by dividing the amount of heat input by the square of the thickness of the flat plate to be heated. FIG. 3A shows the in-plane shrinkage deformation δ _m, and FIG. 3B shows the bending deformation δ _b . (C) shows the upper surface deformation amount δ _u = δ _m + δ _b and the lower surface deformation amount δ _l = δ _m −δ _b obtained by combining the in-plane shrinkage deformation δ _m and the bending deformation δ _b . In addition, h shows plate | board thickness and Z shows a plate | board thickness direction.
[0015]
If the heating condition is determined for one heating wire in this way, the amount of deformation at the position of the heating wire can be obtained, and the position and the surrounding distortion can be calculated from this amount of deformation. There is an upper limit to the magnitude of strain due to one heating wire obtained in this way. When there are a plurality of heating lines at a constant pitch, it is possible to calculate the strain generated by superimposing the data of one heating line. However, if the interval between adjacent heating lines is too close, the strains interfere with each other and the strain tends to decrease. Therefore, an appropriate interval is adopted. Therefore, if the heating condition is defined, the limit of the strain obtained by the condition can be determined, and the strain data generated for each heating condition is stored as determination data.
[0016]
【The invention's effect】
As is clear from the above description, in the present invention, first, a strain generated when a flat plate is bent into a planned curved surface is calculated by a finite element method. The magnitude of this strain represents the difficulty of bending, and the larger the value, the more difficult it is. The strain generated by the heating condition is determined in advance by experiments or the like, and the selection of the heating condition determines the plate division by limiting the range in which the strain below the strain generated under the condition is distributed. As a result, it is possible to quantitatively carry out the plate splitting that has been performed empirically in the past. In addition, it is possible to perform an appropriate plate division by correcting the plate division determined based on the ease of bending in consideration of the yield of the material, the standard size to be traded, and the like.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an embodiment of the present invention.
FIG. 2 is a diagram showing the relationship between heating time and the amount of deformation that occurs.
3A is a diagram showing the amount of in-plane contraction deformation, FIG. 3B is the amount of bending deformation, and FIG. 3C is a diagram showing the amount of deformation of the upper and lower surfaces of the plate obtained by superimposing the two.

Claims (3)

In order to construct a curved surface by bending a plurality of flat plates, the curved plate splitting method that determines the size of the flat plate before bending, the finite planned strain that occurs when the plane is transformed into the planned curved shape Calculated by the element method, the linear heating condition for generating a predetermined strain is determined according to the magnitude of the strain, the heating condition is selected, and it can be generated under the selected heating condition within the distribution range of the planned strain A method of splitting a curved surface, wherein the splitting is performed based on a range in which the strain of size is distributed. 2. The curved surface splitting method according to claim 1, wherein the planned strain is calculated based on a strain generated when the planned curved surface shape is deformed into a plane. 3. The curved plate division according to claim 1 or 2, wherein the plate division determined according to the distribution state of the planned strain is a plate division that is corrected based on at least one of a standard plate size and a yield of the plate division. Method.

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