JP2666674B2 - Method of bending metal plate by linear heating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used to finish a curved member of a ship, bridge, or other metal structure from an initial shape subjected to a primary processing such as a flat plate material or a press to a target curved surface shape. The present invention relates to a method for bending a metal plate by linear heating.

[0002]

2. Description of the Related Art Generally, when a metal plate used for a ship, a bridge or the like is bent, it is often performed by linear heating. This bending by linear heating is performed by applying linear heating to a predetermined position on a flat plate or a metal plate that has been primarily processed by a press, and using in-plane shrinkage and angular deformation of the plate due to the generated plastic strain. To create the desired three-dimensional shape.

In the bending by linear heating, the amount of in-plane shrinkage and the amount of angular deformation are determined by the heating position, direction and heating conditions of the linear heating. Therefore, these heating positions, directions and heating conditions are important. is there.

[0004] At the current processing site, there is no technology based on a theoretical approach focusing on the target intrinsic strain distribution obtained by calculation for forcibly deforming the initial shape to the target shape. The actual situation is that the heating position, the direction, and the heating conditions are determined based on the intuition and skill of a skilled person while detecting the deviation from the target shape by temporarily disposing the heater on the top.

However, in recent years, problems such as the aging of these skilled workers and the accompanying decrease in the number of workers have become remarkable.

Therefore, in recent years, in view of such a situation, a method of bending a plate by linear heating can be performed without requiring special skills, and the processing capability can be improved without requiring special skills. Has been proposed and a patent application has been filed (Japanese Patent Application No. 3-237948).

The recently proposed method determines the position, direction and generated intrinsic strain (intensive strain distribution) of a linear heating wire based on an elastic analysis of a finite element method (FEM). As shown in FIG. 21, first, after inputting geometric information on the initial shape and the final formed shape (step I), mesh division of the FEM corresponding to the initial shape is performed (step II). Next, forcibly elastically deform from the initial shape to the final shape, calculate the strain that occurs in the process, separate the calculated strain into in-plane components and bending components, and display the main strain distribution on the graphic screen Display (Step III). Next, paying attention to the strain distribution in the plane, the area where the main strain of compression is large is selected as the heating area, and the direction of heating is perpendicular to the direction of the main strain (step IV). Attention is paid to the region where the absolute value of the bending strain is large, as a heating region, and the direction of heating is set to a direction perpendicular to the main direction where the absolute value of the strain is the maximum (step V).

Next, in order to determine the magnitude of the intrinsic strain to be generated, a forced deformation FEM elasticity analysis in which the stiffness of the elements belonging to the heating region is made smaller than that of the remaining portion is performed again, and the strain concentrated in the heating region is determined. The value of the generated intrinsic distortion is calculated from the value of (step VI). Thereafter, based on these calculations, linear heating is performed to generate an intrinsic strain, thereby processing into a predetermined final shape (step VII).

[0009]

The method proposed and filed recently has the advantage that the bending of the plate by linear heating can be carried out easily, so that it can be carried out without relying on the expert's intuition. However, in formulating the heating method, steps IV and V
The direction of the heating line and the magnitude of the generated intrinsic strain are approximately determined by separating the target intrinsic strain into pure in-plane components and bending components. Depending on the heater, it is impossible to achieve pure in-plane shrinkage or bending, and no matter what heating conditions are selected, it always contains a certain ratio of both in-plane strain components and bending strain components . Therefore, even if two heating conditions, that is, the in-plane component superiority and the bending component superiority, are selected, it is considered difficult to realize a correct heating line direction and a target intrinsic strain state. Forced deformation FEM as shown in (a) to (b) of FIG.
In the case of performing an elasticity analysis, in general, the in-plane component of the target intrinsic strain may appear not only contraction strain but also extension strain as shown in FIG. Further, in the forced deformation FEM elasticity analysis in which the rigidity of the heating section is reduced for determining the magnitude of the intrinsic strain, the elongational strain may also appear. Bending by linear heating is a method of processing using compression plastic strain generated in a heating portion, and cannot impart elongation strain (← → mark) shown in the lower part of FIG. Therefore, in order to be able to work on the target shape only by linear heating, the above FEM calculation results must all be shrinkage strain (→ ← mark). FIG. 22
In (c), it is necessary to apply uniform shrinkage strain limited to at least the stretch strain portion or as a whole.
This corresponds to reducing the target shape or increasing the initial shape. Similarly, in order to achieve a certain amount of bending strain by heating from one side, some in-plane shrinkage is inevitable. Due to these extra shrinkages, the finished target shape has insufficient in-plane dimensions. Although this has been known qualitatively in the past, these cannot be compensated quantitatively, so at the present time, a sufficient margin based on empirical rules must be taken in advance and the final There is a possibility that extra work for trimming and, in some cases, insufficient dimensions may occur. It is well known that in the case of linear heating, not only the contraction strain in the direction perpendicular to the heating wire but also the contraction strain in the heating line direction is always small, but it always accompanies it. Then, it is considered difficult to accurately realize the target eigendistortion distribution. Also, the quantitative relationship between the heating conditions and the generated intrinsic strain is not mentioned in the recently proposed and filed method, so it can be inferred from experience and intuition from the current field technology, bending template and initial shape. The method of selecting and implementing the heating conditions that will generate the necessary deformation amount of each part based on experience is adopted, but as a result of accumulating multiple stages of estimation based on experience and intuition, difficulties, errors, There are problems such as large variations, limited number of people who can do it, and long time to learn.

In view of the above, the present invention further advances the above-mentioned recently proposed and filed bending method for a plate by linear heating to eliminate the above-mentioned problems, and can be carried out by a layman when a target shape is given. The purpose of the present invention is to realize a target intrinsic strain only by a desired heating condition.

[0011]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention firstly inputs geometric information of an initial shape and a target shape in order to bend a metal plate from an initial shape to a final target shape. Then, mesh division by the finite element method is performed based on the initial shape, the divided shape is mapped onto the target shape, and the target eigendistortion distribution is calculated by forcibly deforming from the initial shape to the target shape. , The obtained target eigenstrain distribution is expressed by generated eigenstrain generated by multiple heating lines, and at this time, the quantitative relationship between the heating conditions and the generated eigenstrain for the combination of the heating device and the workpiece is similar. After introducing the rules, the heating lines in each element are connected and the position, direction, and heating conditions of the heating lines of the entire plate are determined and displayed, and then the metal plate is bent. Method. Alternatively, a method may be used in which a metal plate is bent after an elastic simulation for confirming a bent shape is performed by giving a generated intrinsic strain obtained when a heating condition is given to an initial shape. .

[0012]

[Function] After a metal plate is forcibly elastically deformed from an initial shape to a target shape to obtain a target eigenstrain distribution in each element, the target eigenstrain distribution is expressed as an eigenstrain generated by a plurality of heating wires. Further, when the generated intrinsic strain is given based on the quantitative relationship obtained by introducing the similarity rule, since the corresponding heating condition is obtained, a plurality of heating lines under the obtained heating condition are used. Heating may be performed, and it is not necessary to rely on a skilled engineer. Further, it is also possible to predict in advance how the target shape is achieved by giving the generated intrinsic strain to the initial shape.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the present invention in which a flat plate having an arbitrary peripheral shape or a steel plate or a metal plate other than steel having an arbitrary curved surface as an initial shape is bent into a target shape (another arbitrary peripheral shape and a curved surface shape). In the flowchart showing the method, after inputting geometric information regarding the initial shape and the target shape (step 1), FIG.
As shown in (a), the mesh is divided by the finite element method (FEM) (step 2), and the divided shape is formed by a suitable mapping method for mapping the initial shape to the target shape as shown in FIG. The image is mapped onto the target shape of the plate P (step 3). Next, each element node position in the initial shape is forcibly elastically deformed to a corresponding element node position in the target shape by FEM calculation to calculate a strain distribution (target intrinsic strain distribution) in each element (step 4). . At this time, by appropriately selecting the mapping method when forcibly deforming, a target intrinsic strain distribution suitable for the processing method can be obtained, and it is possible to determine a shrinkage allowance associated with the mapping method and the processing method.

Next, as a method of heating, a target intrinsic strain distribution in the element obtained in step 4 is converted into a concentrated strain distribution (generated intrinsic strain) generated by a plurality of heating lines.
(Step 5). In this case, when realizing the target eigenstrain distribution with the generated eigenstrain in step 5 above, for a given combination of a heater (gas flame, high-frequency induction heater, laser light, etc.) and a workpiece, Since a quantitative relationship between the heating conditions (heat input amount per unit time, moving speed, etc.) and the generated intrinsic strain is required, this relationship is determined (step 6). The quantitative relationship between the heating conditions and the generated intrinsic strain is generally determined by accumulating experimental data or by giving a heat input condition (heat input distribution or a temperature distribution that changes in a time series) by thermo-elastic-plastic FEM analysis. It is obtained by calculating the generated intrinsic strain on the metal plate at the time. A feature of the present invention is that, when calculating the relationship between the above-mentioned heating conditions and the generated intrinsic strain using a thermo-elasto-plastic FEM program whose validity has been confirmed by a demonstration experiment, a linear heating Of the similarity rule for the thermo-elastic-plastic deformation problem due to heat and the efficient calculation method using the governing parameters derived from it, and the heating by rearranging the calculated results in a generalized form with those parameters It is an object of the present invention to provide a means for efficiently obtaining a generated intrinsic distortion when a condition is given.

Next, the positions and directions of the heating lines of the entire plate and the heating conditions are determined by connecting the heating lines in each of the above elements and displayed (step 7), and are obtained in steps 5 and 6. By applying the generated intrinsic strain under the given heating conditions to the initial shape, the elasticity simulation of the bent shape is performed and confirmed (step 8). Thereafter, linear heating using a heater controlled manually or by NC is performed according to the heating method determined in step 6 and displayed in step 7 (step 9).

[0017] The metal plate is given a generated intrinsic strain by the heating method determined in the steps 1 to 9 so that the metal plate can be bent into a target shape.

The details will be described below.

Steps 1 to 3 correspond to steps I and II in FIG.

In step 4, the proper intrinsic strain distribution suitable for the processing method is obtained by appropriate selection of the mapping method when forcibly deforming, and the contraction allowance accompanying the mapping method and the processing method can be determined. The simplest example of a method for quantitatively obtaining the shrinkage margin required in the bending process will be described. First, in order to eliminate a portion of in-plane elongation strain, for example, x, y of a metal plate P shown in FIG. A contraction strain having an absolute value equal to the maximum elongation strain in both directions is applied uniformly to the entire plate, that is, to all elements. This uniform addition is equivalent to adding a specific correction to the mapping method from the initial shape to the target shape without considering the shrinkage allowance. Thus, the shrinkage allowance in this case can be easily calculated in a uniform manner along each side as shown in FIG. 3 by multiplying the applied uniform strain by the length of the plate. As for the shrinkage due to bending, assuming that the bending component ratio under the selected heating condition is α, the maximum bending strain multiplied by 1 / α times the length of the plate becomes the shrinkage allowance (same uniform shrinkage). When distortion is applied). The overall shrinkage margin can be obtained by performing the same operation in the vertical and horizontal directions of the board. That, then ^{_{Δl x = ε mx max l x}} + ε bx max l x / α Δl y = ε my max l y + ε by max l y / α, when formulating a heating method of Step 5, realizing the desired intrinsic distortion In order to make the target intrinsic strain distribution of the metal plate P have six independent components (the in-plane strains ε ′ _xu , ε ′
_yu , γ _xyu and the in-plane strains ε ′ _xl , ε ′ _yl , γ _xyl ) of the lower surface, and then the intrinsic strain generated by one linear heating is shown in FIG.
(A) In-plane contraction amount δ _m (= (δ _mu + δ _ml ) / 2) and angular deformation φ (or α = (δ _u ) in the direction perpendicular to the heating line a as shown in the metal plate P in (B). −δ _l ) / (bending component ratio represented by (δ _u + δ _l )). This makes the above 6
The individual strain components can be realized by appropriately arranging a plurality of heating wires or adjusting heating conditions. That is, six conditional expressions for determining the arrangement, the direction, and the heating condition characteristic value of the plurality of heating lines are obtained from the six target intrinsic strain components.
For example, the intervals and directions of the heating wires when the two types of characteristic values of the generated intrinsic strain are given can be determined. In addition,
In the above, the intrinsic strain generated by one linear heating is δ
_The description has been given in terms of two characteristic values of _m and α. On the other hand, an equivalent external force P _L and an equivalent moment M _L required to cause a deformation equivalent to the contraction deformation in the heating line direction are added. If the generated intrinsic strains are aggregated by the total of four characteristic values and the same method is used as described above, the arrangement, direction, or heating conditions of the heating wire can be adjusted in consideration of the influence of shrinkage in the heating direction caused by heating. A generation characteristic distortion characteristic value can be determined.

Now, as one embodiment, for the above-mentioned plurality of heating wires, when the target eigenstrain is realized by two heating wires, that is, as shown in FIG.
The components (in-plane strains ε ′ _xu , ε ′ _yu , γ _xyu on the upper surface and in-plane strains ε ′ _xl , ε ′ _yl , γ _xyl on the lower surface) are _separated by two heating lines a and b having different characteristic values. The case of realization will be described. When the subscripts S and L are used to represent the respective heating lines a and b, the characteristic values (δ _mS , δ _mL , α _S , α _L ) of the four generated intrinsic strains under two heating conditions, The heating lines a and b are x
Angles θ _S , θ _L with the axes, two heating lines a, b
The heating method can be determined by eight parameters obtained by summing the heating line intervals d _S and d _L. In order to achieve the target intrinsic strain, the following six conditional expressions are imposed (however, in the case of both upper surface heating).

Ε ′ _xu = −δ _mS / d _S (1 + α _S ) sin ² θ _S −δ _mL / d _L (1 + α _L ) sin ² θ _L (1-1) ε ′ _yu = −δ _mS / d _S (1 + α _S ) cos ² θ _S −δ _mL / d _L (1 + α _L ) cos ² θ _L (1-2) γ _xyu = −δ _mS / d _S (1 + α _S ) sin 2θ _S −δ _mL / d _L (1 + α _L ) sin2θ _L (1-3) ε ′ _xl = −δ _mS / d _S (1-α _S ) sin ² θ _S −δ _mL / d _L (1-α _L ) sin ² θ _L (1-4) _{ε 'yl = -δ mS / d} S (1-α S) cos 2 θ S -δ mL / d L (1-α L) cos 2 θ L (1-5) γ xyl = -δ mS / d S (1−α _S ) sin 2θ _S −δ _mL / d _L (1−α _L ) sin 2θ _L (1-6) Therefore, two of the eight parameters can be freely selected. Even if designated, the target eigendistortion can be realized by selecting the remaining six parameters so that the above six conditional expressions are satisfied.

When all the eight parameters are determined, a specific heating method in the element is determined.
In this way, for example, when the heating conditions are determined for all 16 elements as shown in FIG. 6, the entire plate can be finished to the desired shape by repeatedly or intermittently heating them. Furthermore, δ _mS , δ _mL
And alpha _S, be adjusted by varying the heating conditions the size of the alpha _L, it is possible to perform the heating distance d _S, from fine smooth bending with narrowed d _L, until simple rough bending.

In this embodiment, for example, assuming that two types of heating devices are used, in FIG. 5, one heating is performed by linear heating (shown by a suffix S) by a gas flame, and the other heating is performed by another appliance ( (Indicated by a suffix L). It is assumed that the heating condition of another instrument is fixed, or the characteristic value data of the generated intrinsic strain is obtained only under a specific heating condition. Therefore, δ _mL and α _L of the eight parameters must be specified in advance. In this case, in order to achieve the target eigenstrain state, the aforementioned 6
The remaining six parameters θ _L , d _L , θ _S , d _S , δ _mS , and α _S are obtained from the conditional expressions (1-1) to (1-6). Among them, δ _mS and α _S are determined by the heating conditions of the gas flame. For example, it is necessary to determine the heating conditions Q and v so that δ _mS and α _S obtained using FIGS. 14 and 15 are obtained. Can be.

Next, FIG. 7 shows another embodiment in which the target eigenstrain is realized by a plurality of heating wires, in which the target eigenstrain is realized by three different heating wires a, b, and c. . The heating method is determined by twelve parameters, and six of the twelve parameters can be freely set in advance.

In the case of this embodiment, for example, the characteristic value δ _{mS of} the intrinsic strain generated by the three heating wires a, b, c,
Even when δ _mM , δ _mL , α _S , α _M , and α _L are fixed from the operation conditions of the apparatus, three heating line directions θ _S , θ _M ,
By properly selecting θ _L and the heating line intervals d _S , d _M , and d _L so as to satisfy the six conditional expressions, the target intrinsic strain can be achieved.

FIG. 8 shows still another embodiment in which a target intrinsic strain is realized by a plurality of heating wires, four heating wires a, b, and
The case where the target intrinsic distortion is realized by c and d is shown.

In this case, many implementation methods are conceivable. As an example, two types of heating conditions of the heating wires a and b are set, and two heating wires (each of which is mutually different) are set for each condition. Fixed angles ψ _S , ψ _L intersect each other), the heating method is δ _mS , δ _mL ,
1 of α _S , α _L , θ _S , θ _L , d _S1 , d _S2 , d _L1 , d _L2
It is determined by 0 parameters, and 4 parameters out of 10 can be freely set in advance.

In this embodiment, for example, the characteristic values δ _mL and α _{L of} the generated intrinsic strain corresponding to one of the heating conditions are specified, and only one of them is specified in the specified direction θ _L and the interval d.
_Assuming that the construction is performed at _L1 , this can be achieved by properly selecting the remaining parameters δ _mS , α _S , θ _S , d _S1 , d _S2 , and d _L2 so as to satisfy the six conditional expressions.

Next, a specific embodiment for obtaining a quantitative relationship between the heating condition in step 6 and the generated intrinsic strain will be described. (A) In the case of determining the generated intrinsic strain by giving a heating condition When a plate having a plate thickness h = 16 mm and a plate thickness h = 16 mm is linearly heated at a heat source moving speed v = 15 mm / sec using a gas flame having an input heat quantity of Q = 3815 cal / sec. An example of obtaining _δm and α will be described. In this case, the following material physical property values are used.

[0031] It is. β is a parameter proportional to the maximum temperature of the surface of the plate heated by the heat source, and ζ is a parameter corresponding to the heat source moving speed.

FIG. 14 shows a change in the amount of angular deformation due to the parameters β and ζ, and FIG. 15 shows a change in the amount of in-plane lateral contraction due to the parameters β and ζ. When reading the _m, it can be seen that the _{φ = 0.005 rad δ m = 0.001mm} . The angular deformation component ratio α is α = φh / 2δ _m = 40.

When the similarity rule of the thermal elasto-plastic deformation due to the moving heat source is introduced, the shape of the target plate and the width of the heat source are geometrically similar, and the material of the metal plate is the same, and the thermal and mechanical properties are the same. , The above parameters β, β
Is the same, it can be seen that the temperature distributions at the similarized time and position match, and similar deformation occurs.

As an application example of the similarity rule, FIGS.
Table 1 compares the calculation results in which specific numerical values are set for the two cases shown in FIG.

[0035]

[Table 1] In this example, an axially symmetric heat source is shown as shown in the figure, but various methods can be considered as the heat source. The method proposed here can be utilized corresponding to those heat source shapes.

Here, the plate thickness of 8 mm and the width of 30 mm in FIG.
A model having a thickness of 0 mm and a length of 300 mm is referred to as M8, and a model having a plate thickness of 16 mm, a width of 600 mm, and a length of 600 mm in FIG.

As can be seen from Table 1, the geometric shape is 2
In the case of double, in order to generate similar deformation, heat input Q
It should be understood that は must be twice and the heat source moving speed v must be 1/2 times.

FIGS. 10 and 11 show the heating line of each of the plates M8 and M16, the cross-sectional position at the center in the plate length direction, and the temperature history accompanying the movement of the heat source occurring on the front and back surfaces of the plates.

The vertical axis of the graph indicates the temperature of the section. The horizontal axis of the graph is the standardized relative time, but also corresponds to the position in the plate length direction. Τ = 0.5 is the center in the plate length direction (Y direction in FIG. 8), τ = 1 .0 is the end. β, ζ
It can be seen that the temperatures at the corresponding positions in M8 and M16 are equal.

FIG. 12 shows the history of the angular deformation caused by the movement of the heat source in the cross section at the center in the longitudinal direction of the plate on the heating wire of M8 and M16. The vertical axis is the deformation angle (radian), and the horizontal axis is the same as in FIGS.

FIG. 13 shows the history of contraction deformation in the width direction of the sheet at the center in the length direction of the plate on the heating wire of M8 and M16.

In FIGS. 12 and 13, the state of change with time and the difference in the amount of deformation itself when the heat source moving speed is fast (ζ = 4.4) and when it is slow (ζ = 1.9) are clearly seen. I can take it.

FIG. 14 is a graph showing the results of series calculations performed by changing β and ζ.

Β is 3.2 × 10 ³ (corresponding to the maximum temperature on the plate surface of about 445 ° C.) 4.4 × 10 ³ (corresponding to the maximum temperature of the plate surface of about 615 ° C.) 5.7 × 10 ³ ( (Corresponding to the maximum temperature of about 785 ° C. on the plate surface).

The vertical axis represents the amount of angular deformation (radian), and the horizontal axis represents ζ.
It can be seen that the larger the β (the higher the surface temperature), the greater the amount of angular deformation (corresponding to the heat source moving speed).

The dotted line connects points having the same Q / v (heat input amount per unit length). This shows that even if the heat input amount per unit length is the same, the deformation amount is different if the heat input speed is different.

FIG. 15 shows the relationship between the amount of shrinkage in the horizontal direction and the parameters in the cross section at the center in the longitudinal direction of the plate on the heating line.

The vertical axis is the amount of contraction, the horizontal axis is the same as in FIG. 14, and the dotted line is the same as in FIG.

FIG. 16 shows the relationship between the shrinkage strain in the width direction and the parameter at the center position in the width direction on the same cross section as in FIG. The amount of bending strain is represented by a difference in plastic strain between the plate surface and the center of the plate thickness. FIG.
14 can be considered as a figure that can be read unifiedly with the tendency shown in FIG.

FIG. 17 shows the relationship between bending deformation (radian) and lateral shrinkage (mm) when the degree of concentration of the distribution is changed, considering an axially symmetric heating source as shown in FIG. Assuming that heating is given as a forced heat flux q from the plate surface, q is an axisymmetric Gaussian distribution as

[0051]

(Equation 1) Here, r is the distance from the center of the heat source qmax: κ in the case of the heat flux at the center of the heat source is plotted on the horizontal axis. in this case,
κ represents the degree of spread of q (r). The larger κ is, the more concentrated, and the smaller κ, the more diffuse.

The relationship between q and Q is Q = πqmax / κ.

According to this graph, even when the heat input amount and the heating rate are the same, the deformation is different if the heat input distribution pattern of the heat source is different. That is, an important finding that the efficiency of bending is greatly changed is provided. (B) To determine the generated intrinsic strain by specifying the maximum temperature Determine the heat source moving speed for heating with the maximum temperature kept at 500 ° C or less under the same gas flame and plate thickness conditions as in (A). To determine the characteristic value of the generated intrinsic strain. As mentioned above, the temperature field is characterized by two parameters, β and ζ. FIG. 18 arranges the maximum temperatures T _s and _max of the plate surface on the vertical axis based on the calculation results of the temperature distribution in which β and ζ are systematically changed. In case (A), v
= 15 mm / sec, β = 4.4 × 10 ³ , ζ = 3.
It was 4. The maximum temperature at this time is about 600 from FIG.
° C. In order to lower the maximum temperature to 500 ° C., it is necessary to increase v and lower β. From the figure
In the range of> 3.0, it can be seen that T _s and _max hardly depend on ζ, so only β needs to be adjusted. v = 2
If 2.6 mm / sec, β = 3.6 × 10 ³ and T
_It can be seen that _s , _max = 500 ° C. At this time
Is

[0054]

(Equation 2) Becomes When these values of ζ and β are applied to FIGS. 14 and 15, angular deformation φ = 2 × 10 ⁻³ rad and lateral contraction δ _m = 0.5
It becomes about ^10-3 mm. (C) When Determining Heating Condition from Generated Eigenstrain When formulating a heating method, the characteristic value of the generated eigenstrain may not be able to be moved for some reason (for example, δ in the first embodiment of the heating method formulation method). _{mS, α S).} In this case, it is possible to know what heating conditions (Q, v) should be used for heating. It is assumed that the characteristic value of the generated intrinsic strain is specified as δ _m = 10 × 10 ⁻³ mm and α = 7.2 when the plate thickness is 16 mm. The angular deformation φ is φ = 2αδ _m / h = 9 × 10 ⁻³ (rad.).

In FIG. 19 where FIG. 14 is reprinted, a line parallel to the horizontal axis is drawn such that the angular deformation is 9 × 10 ⁻³ rad.
Similarly, in FIG. 20 in which FIG.
Draw a line parallel to the horizontal axis which is 0 × 10 ⁻³ mm. While changing the value of ζ, various lines parallel to the vertical axis are drawn, and a ζ position where β coincides between FIG. 19 and FIG. 20 at the intersection of the horizontal line and the vertical line is searched. As a result, when ζ = 2.1, the value of β at the intersection in both figures becomes equal, and β = approximately 5.2 × 10 ³ .

[0056]

(Equation 3) Therefore, a gas flame of 2805 cal / sec has a strength of 5.8 mm /
If linear heating is performed at a moving speed of sec, the required δ _m = 10 ×
10 ⁻³ mm, α = 7.2 will be achieved.

Steps 5 and 6 as described above
When bending the metal plate by the heating method determined in the above,
Given the required generated intrinsic strain, it can be bent into the target shape. In addition, if necessary, the intrinsic shape generated by heating by the heating method determined in the above steps 5 and 6 is given to the initial shape in step 8 and the elasticity of the bent shape is simulated and confirmed. Can be.

[0058]

As described above, according to the method of bending a metal plate by linear heating of the present invention, the following excellent effects can be obtained. (i) Since the target eigenstrain distribution in each element is calculated, and the target eigenstrain distribution in the obtained element is expressed by the generated eigenstrain generated by a plurality of heating wires,
In general, when the heating method is determined from the target shape or the target intrinsic strain, it is usually an inverse problem, and after sufficiently storing data of the deformation state or the generated intrinsic strain when various heating methods are given, From this, a procedure must be taken to find the heating method that best suits the purpose. However, according to the present invention, if a target shape is given, even a layman can find a bending method according to the flow shown in FIG. It has the effect, and even if the process for defining this heating method is adopted, if the characteristic value of the generated intrinsic strain to be given in the element is specified, the heating as shown in FIGS. It is necessary to provide a data bank that gives the relationship between the condition and the generated intrinsic strain. However, in the present invention, the number of heating lines is increased to increase the number of heating lines. Eg to characteristic values of the product-specific strain made it possible to achieve the desired intrinsic distortion just previously Known heating conditions). (ii) Since the intrinsic strain generated by the specific heating conditions includes the bending component and the in-plane component at the same time, the required generated intrinsic strain is obtained (that is, the required eigen-strain is equal to the value for each of the bending component and the in-plane component) Has the problem of having to solve the inverse problem to find the cause by knowing the result. In solving this problem, no matter what kind of transformation, that is, the generation eigendistortion is required, However, in the present invention, since a quantitative relationship between the heating condition and the generated intrinsic strain is given over a wide range, an appropriate heating condition when the generated intrinsic strain is given can be obtained. The optimal heating device can be designed as required. Furthermore, by introducing the similarity rule, it is possible to estimate large objects by model experiments with small dimensions, and to expand the application range of the calculation results when trying to find the intrinsic strain generated under various heating conditions. And the amount of calculation for accumulating quantitative data covering the whole and the amount of experiments can be greatly reduced. (iii) According to (i) and (ii) above, the linear heating and bending method, which had to rely on a skilled technician because it was a complicated phenomenon including many factors of trial and error, It is now possible to select the optimal processing method.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an embodiment of the method of the present invention.

FIGS. 2A and 2B show mapping from an initial shape to a target shape and forced deformation. FIG. 2A is a diagram of FEM mesh division, and FIG.

FIG. 3 is a diagram illustrating an example of how to set a shrinkage allowance.

4A and 4B show a state when linear heating is performed by one heating wire, wherein FIG. 4A is a perspective view of a plate, and FIG. 4B is a cross-sectional view of FIG.

FIG. 5 is a diagram illustrating an example of a case where a target intrinsic strain is realized by two heating wires under different heating conditions.

FIG. 6 is a schematic diagram of heating wire connection for each element in the case of FIG. 5;

FIG. 7 is a diagram showing an example in which a target intrinsic strain is realized by three heating wires under different heating conditions.

8 is a diagram corresponding to FIGS. 5 and 7 in the case where there are two types of heating conditions and two corresponding heating lines.

9A and 9B show an application example of the similarity rule. FIG. 9A is a perspective view of a model M8, and FIG. 9B is a perspective view of a model M16.

FIG. 10 is a diagram showing a comparison of temperature histories at corresponding positions of models M8 and M16 when parameter ζ = 4.4.

FIG. 11 is a diagram showing a comparison of temperature histories at corresponding positions of models M8 and M16 when parameter ζ = 1.9.

FIG. 12 is a diagram showing a comparison of temporal changes in angular deformation at corresponding positions of models M8 and M16.

FIG. 13 is a diagram showing a temporal change of the in-plane lateral contraction amount at the corresponding cross section of the models M8 and M16.

FIG. 14 is a diagram showing a change in the amount of angular deformation according to parameters β and ζ.

FIG. 15 is a diagram showing a change in an in-plane lateral contraction amount according to parameters β and ζ.

FIG. 16 shows parameters β and の of plastic strain in a central section.
FIG. 6 is a diagram showing a change due to

FIG. 17 is a diagram showing the influence of the spread of a heat source on deformation.

FIG. 18 is a diagram showing a change in maximum temperature with parameters β and ζ.

FIG. 19 is a diagram showing angular deformation and reading β from a parameter ζ.

FIG. 20 is a diagram showing reading of β from a lateral contraction and a parameter ζ.

FIG. 21 is a flowchart showing an embodiment of a method of bending a plate by linear heating, which has been recently filed.

FIGS. 22A and 22B show in-plane distortion components when forcibly deformed from an initial shape to a target shape, where FIG. 22A shows the initial shape, FIG. 22B shows the target shape, and FIG. It is an inner principal distortion vector diagram.

[Explanation of symbols]

 1 Step 1 2 Step 2 3 Step 3 4 Step 4 5 Step 5 6 Step 6 7 Step 7 8 Step 8 9 Step 9 a Heating wire b Heating wire c Heating wire d Heating wire P Metal plate

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Isao Negi 3-1-1-15 Toyosu, Koto-ku, Tokyo Ishikawa Shima-Harima Heavy Industries Co., Ltd. (72) Inventor Yukio Ueda 11-1 Mihogaoka, Ibaraki-shi, Osaka, Osaka University Welding Engineering Laboratory (72) Inventor Eiichi Murakawa 11-1 Mihogaoka, Ibaraki City, Osaka Prefecture Osaka University Welding Engineering Laboratory (72) Inventor Rashwan Ahmed Mohammed 11-1 Mihogaoka, Ibaraki City, Osaka Prefecture Osaka University Welding Engineering Research In-house (72) Inventor Yasuhisa Okumoto No. 1 Takaya Umenobe, Higashihiroshima City, Hiroshima Pref.

Claims (2)

(57) [Claims] In order to bend a metal plate from an initial shape to a final target shape, first, geometric information of the initial shape and the target shape is input, and mesh division by the finite element method is performed based on the initial shape. Then, the divided shape is mapped onto the target shape, then the target shape is forcibly deformed from the initial shape to calculate the target eigendistortion distribution, and the obtained target eigendistortion distribution is generated by a plurality of heating lines. In this case, the quantitative relation between the heating condition and the generated eigenstrain for the combination of the heating device and the workpiece is obtained by introducing a similarity rule, and then the The method for bending a metal plate by linear heating, comprising: connecting the above-described heating wires, determining and displaying the position, direction, and heating conditions of the heating wire of the entire plate, and then bending the metal plate. . 2. In order to bend a metal plate from an initial shape to a final target shape, first, geometric information of the initial shape and the target shape is input, and mesh division by the finite element method is performed based on the initial shape. Then, the divided shape is mapped onto the target shape, then the target shape is forcibly deformed from the initial shape to calculate the target eigendistortion distribution, and the obtained target eigendistortion distribution is generated by a plurality of heating lines. In this case, the quantitative relation between the heating condition and the generated eigenstrain for the combination of the heating device and the workpiece is obtained by introducing a similarity rule, and then the By connecting the above heating wires and determining and displaying the position, direction, and heating conditions of the heating wires of the entire plate, by applying the generated intrinsic strain determined when the heating conditions are given to the initial shape, Check the bent shape A method for bending a metal plate by linear heating, wherein the metal plate is bent after performing an elasticity simulation.