JPH11179428A - Method and apparatus for hot bending of steel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily obtain a target finishing shape even when steel bending charastics are dispersed, by working steel into a target shape through repeated heating/cooling of a plurality of times while measuring shapes of steel. SOLUTION: A displacement meter 4 is moved by a displacement meter shifting mechanism 5, horizontalness of an upper flange of a wide-flange shape 1 is measured, and then squareness between a web and a flange is calculated. Based on the result of the calculated squareness and a preliminarily fixed work shop control criterion, a bending position and a bending amount are calculated. Based on the calculation result, a heater shifting mechanism 3 is controlled and a burner position is fixed, and after that local heating of the wide-flange shape is executed with the burner. After retreat of the heater shifting mechanism 3, the displacement meter shifting mechanism 5 is moved and the horizontalness of the flange of the wide-flange shape 1 is measured by the displacement meter 4. In the case that the horizontalness of the flange does not attain to a target value, the previous process is repeated again. In the case hat the target value is attained, the treatment is completed and the wide-flange shape is carried away.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to heat processing of steel materials and steel structures, and is also applicable to heat straightening.

[0002]

2. Description of the Related Art Generally, when a steel material used for a ship, a bridge or the like is bent, it is often performed by local heating. This bending by local heating is performed by applying local heating to a predetermined position of a flat plate-shaped steel material or a steel material primarily processed by a press, and utilizing the in-plane shrinkage and angular deformation of the steel material due to the generated plastic strain. It creates the original shape. In addition, this local heating technique is also used for the straightening treatment of steel materials. For example, shape defects that occur when rolling or welding an H-section steel, in particular, the flange surface is bent without being orthogonal to the web. It is also used to correct the flange surface so that the flange surface is perpendicular to the web when the defect occurs.

In the above-described bending by local heating, the amount of in-plane shrinkage and the amount of angular deformation are determined not only by the steel composition and structure but also by the heating position, direction and heating conditions of the local heating. Conditions are important parameters.
At the current processing site, in order to correct and deform from the initial shape to the target shape, the heating position is determined by the skilled worker's intuition and skill while detecting the deviation from the target shape by temporarily arranging a plurality of bending mold plates on the steel material. In fact, the direction, the heating conditions are determined.

However, in recent years, problems such as the aging of these skilled workers and the accompanying decrease in the number of workers have become more prominent. Therefore, in view of the above situation, a technique has recently been proposed in which local heating work requiring skill can be performed without requiring special skills, and the processing ability can be improved.

For example, in Japanese Patent Application Laid-Open No. 7-75835, the finite element method is used, first, geometric information of an initial shape and a target shape is input, and mesh division of the finite element method is performed based on the initial shape. Then, the divided shape is mapped onto the target shape, the target specific strain distribution is calculated by forcibly deforming from the initial shape to the target shape, and the obtained target specific strain distribution is arranged in a plurality of heating lines. Alternatively, it is expressed by the generated eigenstrain generated by adjusting the heating conditions, and at this time, the heating conditions and the generated eigenstrain for the combination of the heating device and the work material obtained by introducing an experimental, analytical, or similarity rule Then, for each element, the combination of heating intensity and heating direction,
After calculating and displaying the heating line interval, the elasticity simulation was performed to confirm the bent shape by applying the generated intrinsic strain obtained when the heating condition was given to the initial condition, and then the metal plate It is disclosed that a bending process is performed (line 11 from the bottom of the third row to row 6 from the top of the fourth row).

By applying the present invention, it is possible to predict in advance how the target shape will be achieved, and to heat a predetermined position in a predetermined direction for a predetermined time using a stationary heat source under the obtained heating conditions. It is often said that it is not necessary to rely on a skilled engineer (lines 15 to 18 from the fourth row). Further, by heating the metal plate locally by a step heating method of continuously heating for a certain period of time while the heater having the elongated linear or rectangular heating unit is stationary,
Stationary heating results in a simpler operation or automation device than a local heating system that uses a moving heat source for continuous local heating. Line 21).

[0007]

However, the prior art shown above is not applicable to the processing of thick plates such as shipbuilding, but is applied to the processing of steel structures, particularly long ones such as H-shaped steel. Has a problem. That is, steel structures use various types of steel materials, so the high-temperature characteristics of each steel material, such as temperature-dependent yield stress, temperature-dependent thermal expansion coefficient, or internal stress generated in the steel material manufacturing process, are larger than steel materials. Due to the variation, even if the same heating conditions are applied, the distortion that occurs, that is, the amount of bending greatly varies in each steel material, and there is a problem that it is difficult to obtain a target shape with good dimensional accuracy. This problem is serious for long objects having a large range.

[0008] The present invention provides a moving heating method in which the bending characteristics of the processed steel material are varied, and even when the processing amount is large and the range is wide, the target heating shape can be easily obtained. An object of the present invention is to provide a method and apparatus for applying a heating bending method.

[0009]

The present inventors investigated the relationship between the temperature distribution and the stress distribution in local heating using a moving heater, and found the hysteresis of the repetitive strain when the same line was repeatedly heated. As a result of examining the progress of ratchet distortion accumulated by the hysteresis, the following findings were obtained.

That is, as shown in FIG. 2A, considering the state of heating by a heater that moves in the direction A and performs local heating linearly, when the heater approaches a certain point, the temperature rapidly increases. Rises to the highest temperature when passing through the heater, and gradually cools down after passing.From the viewpoint of the transitional temperature distribution when the heater is located at a certain point, as shown in the figure, An oblong temperature distribution having a long diameter in the local heating direction is obtained.

As shown in FIG. 2 (b), in this temperature distribution, in the portion where the temperature suddenly changes due to the approach or passage of the heater, the tensile stress is applied immediately before the heating from point a to point b, and d is applied from point c to d. Compressive stress is generated in the rapidly heated portion up to the point. As a result, compressive plastic strain is left, and after cooling, FIG.
As shown schematically in (c), bending occurs in the steel material. However, in the cooling process after the point d, since the temperature gradient is very gentle, internal stress is not generated enough to generate tensile plastic strain enough to offset the compressive strain.

FIG. 3 shows the relationship between the stress σ and the strain ε from the point a to the point d. In FIG. 3, the horizontal axis indicates strain ε and the vertical axis indicates stress σ. The upper diagram shows the hysteresis, and the lower diagram shows the ratchet distortion accumulated by repeated heating. Here, assuming that σb is the tensile stress and σc is the compressive stress generated in the sudden temperature change portion, the strength generally decreases at high temperatures, so the yield stress σ when the compressive stress is applied is
Since yc is smaller than the yield stress .sigma.yb when a tensile stress is applied, the hysteresis follows the path of a.fwdarw.b.fwdarw.c.fwdarw.d shown by the solid line, and generates a residual strain .epsilon.1 without closing. This ε1
Causes the bending shown in FIG. 2C as described above,
The corner deforms concavely.

When the local heating is repeated, the second hysteresis starts at the point d of the first time, and a2 → b2 → c2 →
Following the path of d2, a new cumulative residual strain .epsilon.2 is generated. Here, since ε1 and ε2 depend on the heating condition and the steel material, it is expected that ε1 ≒ ε2 under the same heating condition for the same steel material. Then, based on the above findings, the present inventor has found that by repeatedly performing local heating, the accumulated strain amount is increased, and finally, a target machining amount (angular deformation amount θ) can be obtained.

In view of the above, in the present invention, in heating and bending a steel material in which deformation is caused by locally heating the steel material, heating and cooling are repeated a plurality of times while measuring the shape of the steel material. The above problem has been solved by a method of heating and bending a steel material, which is characterized by processing a steel material into a target shape. Here, the cooling includes natural cooling.

Here, the act of "measuring the shape of the steel" includes the act of measuring the amount of deformation of the steel. At that time, it has been found that it is preferable to keep the heating temperature and the cooling temperature constant at least in at least a part of the repetition of the heating and cooling operations.

In any one of the plurality of repetitions of the heating / cooling, the deformation amount δ of the steel material by one heating / cooling and the deformation amount Δ of the steel material required to obtain the target shape are obtained. Is measured, the required number of remaining repetitions is calculated from the value of Δ / δ, and heating and cooling are repeated at the same heating temperature and cooling temperature as the number of times δ is measured, by the calculated number of remaining repetitions, It has been found that this method is suitable as a method for heating and bending steel with high precision.

Further, it has been found that setting the deformation amount δ to a value equal to or smaller than the allowable error range of the target shape is suitable as a method of heating and bending a steel material with high accuracy. Next, as a heating and bending apparatus for a steel material of the present invention, heating means for locally heating a predetermined position of the steel material,
A heating means moving mechanism for moving the heating means in a predetermined pattern, a measuring means for measuring at least one of the shape and the deformation amount of the steel material, and moving the measuring means following the movement pattern of the heating means It has been found that the provision of the measuring means moving mechanism is suitable for solving the above problem. The content of "following the movement pattern of the heating means" will be described later in detail, but does not refer to synchronization in terms of time or position. It refers to moving to measure later.

Preferably, the apparatus further comprises a heating means, a heating means moving mechanism, a measuring means, and a control means for automatically controlling the measuring means moving mechanism according to a predetermined algorithm. Further, it is preferable to have a cooling unit that locally cools the back surface of the heating unit of the steel material, and a cooling unit moving mechanism that moves the cooling unit in synchronization with a movement pattern of the heating unit, and the control unit further includes: Preferably, the cooling means and the cooling means moving mechanism are also controlled.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of a heating bending apparatus according to the present invention. The heating bending apparatus shown in FIG.
Is shown as an example of an apparatus configuration suitable for correcting the squareness of the flange surface of the H-section steel 1 placed on the web. The present apparatus comprises a heater 2, a heater moving mechanism 3 capable of controlling a heating position and / or a heating direction of the heater 2 and movable for local heating, and an H-shaped steel 1 as a steel material. And a displacement meter moving mechanism 5 for moving the displacement meter 4 along the flange surface of the H-shaped steel 1. Also,
If necessary, a cooler 6 for cooling the back surface of the heating section of the H-section steel 1 is provided in the displacement meter moving mechanism 5 so as to be able to move in synchronization with the movement of the heater 2. Here, the cooler 6
Has the function of suppressing the variation in the heating bending deformation by suppressing the temperature rise on the back surface of the heating section.

Here, the heater 2, the displacement gauge 4, and the cooler 6
May be moved by one integrated moving mechanism. Further, the cooler 6 may not be provided along with the displacement meter moving mechanism, but a cooler moving mechanism may be independently provided. In this case, the structure of the cooler moving mechanism may be the same as that of the displacement meter moving mechanism. In FIG. 1, the cooling of the heating unit is performed by heat transfer cooling by air radiation and back surface cooling. However, only cooling to the atmosphere may be performed, and if necessary, a cooler 12 (hereinafter, referred to as a cooling unit) for directly cooling to the heating unit side. A heating unit direct cooling cooler, not shown), and a heating unit direct cooling cooler moving mechanism 13 for moving the heating unit direct cooling cooler 12 after the movement of the heating unit. (Not shown) may be additionally provided. These structures as the cooler and the moving mechanism have the same structure as the cooler 6 and the moving mechanism 5 (also used as the displacement gauge moving mechanism) for the back surface, except that it is preferable to install the cooler and the moving mechanism on the heating surface side. Good. By adding the heating unit direct cooling means, the heating unit can be cooled quickly and the cooling temperature can be controlled with high precision.

FIG. 1 shows a heating and bending apparatus in which peripheral parts such as a control device and utilities are omitted. Here, the displacement meter 4 may be a distance meter or an image sensor. Hereinafter, in FIG. 1, the operation of the heating bending process in the case where the heater 2 is a burner and the cooler 6 is a water-cooled nozzle will be described in the order of steps.

Step 1: The H-section steel 1 is loaded on the table 7 with the web vertically controlled in attitude. Step 2: The displacement meter 4 is moved by the displacement meter moving mechanism 5,
The horizontality of the upper flange of the H-section steel 1 is measured. By performing this measurement, the perpendicularity between the web and the flange is calculated.

Step 3: The bending position and the bending amount are calculated based on the result of the calculated squareness and a predetermined factory management standard. Step 4: The heater moving mechanism 3 is controlled based on the calculated bending position and bending amount, and after positioning the burner, the H-section steel 1 is locally heated by the burner. Here, if necessary, the displacement meter moving mechanism 5 provided with the cooler 6 moves in synchronization with the heater moving mechanism 3 to cool the back surface of the heating section of the H-section steel 1. In the case of the H-shaped steel, the local heating is usually performed while moving the heater horizontally in a cotton-like manner, but it is needless to say that the operation is not limited to such a linear operation. Further, it goes without saying that in order to correct the variation in the deformation of the shape of the H-shaped steel in the longitudinal direction, the operation of the heater may be stopped or the heating conditions may be changed in a part of the linear heating. .

Step 5: After retreating the heater moving mechanism 3,
The displacement meter moving mechanism 5 moves, and the displacement meter 4 measures the flatness of the flange of the H-beam 1. The levelness measurement may be performed after one linear heating is completed, or even during the linear heating, the heater is sufficiently away from the heater and the heating part near the measurement point is cooled, and there is a risk of leveling error. It may be performed at the time when the number becomes low.

Step 6: If the horizontality of the flange has not reached the target value, steps 3 to 5 are repeated again. If the target value has been reached, the process is completed and the H-beam 1 is carried out. The above series of operations are automatically controlled and executed by a control device (not shown). Here, the levelness measurement in step 5 is as follows:
The heating is performed after the heating section of the H-section steel 1 has dropped to a predetermined temperature. This is to measure the amount of residual deformation generated by the heat treatment as accurately as possible. That is, since the internal stress increases with the temperature drop and the amount of deformation increases, the levelness is preferably measured near the operating temperature (usually normal temperature). Therefore, it is usually sufficient to set the cooling temperature to 300 ° C. or less, where the amount of deformation does not change much from the ordinary temperature. Whether the temperature has dropped to the predetermined temperature may be grasped in advance based on the operation data of the natural cooling time, or may be monitored by a temperature sensor (not shown).

In this repetitive heating, at least the surface temperature of the steel material switches between the high temperature level and the low temperature level, and heating is performed. By doing so, the correction amount in one local heating can be accurately grasped, and accurate bending correction can be performed. Here, the term “constant” attained temperature (cooling temperature) at the low-temperature level means that, from the above-mentioned purpose, the variation in the measured amount of deformation is suppressed to a fluctuation in a temperature range that does not occur due to an error. The expression that the ultimate temperature (heating temperature) at the high temperature level is “constant” means that the variation in the temperature range in which the amount of deformation caused by heating is substantially constant is suppressed.

In one of the heating and cooling cycles in which the heating temperature and the cooling temperature are constant, the deformation amount δ due to one heating and cooling is measured, and the remaining deformation amount Δ required at that time is calculated as δ. , The remaining number of times of processing can be calculated. In this application, for example, a target processing degree can be efficiently obtained by the following algorithm. (1) (From the first cycle) Deformation amount δ and Δ / δ (rounded down to the decimal point, the same applies hereinafter) are calculated, and case A: Δ / δ is an appropriate value and the target value ± tolerance at the Δ / δ time When entering, the heating / cooling is repeated a predetermined number of times (Δ / δ times) under the same conditions as the cycle, and the heating processing is completed. It may be performed at any time). case B: When Δ / δ is a large value (that is, δ is too small), the next heating temperature is set to a predetermined value (for example, 10
0 ° C). caseC: If the difference exceeds the target value ± tolerance at the Δ / δ time, set the next heating temperature to a predetermined value (for example, 100 ° C).
Just lower. (2) For cases B and C, measure the deformation amount again next time (1) c
Judge ase AC. Hereinafter, measurement and determination are repeated in the same manner. (3) If case B and case C are repeated alternately in (2), the amount of change in the heating temperature is reduced.

By incorporating such an algorithm into the control system, the target shape can be automatically achieved. In the above algorithm, case A and
If, instead of case C, case A ': Δ / δ is an appropriate value and δ is a value equal to or less than an allowable error range (allowable maximum value-allowable minimum value), heating / cooling is performed under the same conditions as the cycle. A predetermined number of times (Δ / δ
Times) Repeat to end the heating processing. caseC ': If δ is larger than the allowable error range (allowable maximum value-allowable minimum value), the next heating temperature is lowered by a predetermined value (for example, 100 ° C.). May be used. If δ is less than the allowable error range,
This is because it can be expected to fall within the target value ± tolerance at the Δ / δ time.

The “proper value” in case A varies depending on the application, but generally within 10 times from the viewpoint of work efficiency.
It is preferable that the number is at most 20 times. Further, as an application, under processing conditions in which the deformation amount is large and the allowable error range is small, first, a "temporary allowable error range" larger than the original allowable error range is set, and with a relatively large δ,
Processing is performed to within the tentative allowable error range by the above algorithm. Then, with the smaller δ, processing can be performed by the above algorithm to within the true allowable error range. It is needless to say that the “temporary allowable error range” is set so as not to include excessive machining beyond the original allowable error range. In this way, approach to target value is 2
By dividing into stages or, if necessary, further stages, it is possible to efficiently perform extremely large deformation and high precision bending.

In order to correct the variation in the deformation of the shape of the H-section steel in the longitudinal direction, a process of stopping the operation of the heater or changing the heating condition in a part of the linear heating is performed. Has already been mentioned. In order to provide the above-mentioned algorithm with such a function of correcting variation, for example, when calculating Δ / δ, Δ / δ is calculated for each longitudinal position, and in a portion where the required number of processes is smaller than other portions, This can be easily realized by stopping heating only that portion during the excessive number of heat treatments. Of course, the heating temperature or the like may be changed instead of the number of times of heating.

FIG. 6 exemplifies a block diagram of a control system capable of automatically controlling the heating bending in accordance with, for example, the above algorithm. FIG. 6A is an example of a control system suitable for the heating bending apparatus illustrated in FIG. In this example, the controller 8 includes a main controller 9 and a heating / cooling controller 10a. The main controller 9 manages the heating / bending processing cycle of the above steps 1 to 6, sets the heating temperature of the next step according to the above algorithm, and sends a heating temperature command to the heating / cooling controller 10a. The heating / cooling temperature controller 10a provides the necessary heating power of the heater (such as the amount of gas in the gas burner),
A heater moving speed and the like are calculated to control the heater 2 and the heater moving mechanism 3, and a cooling condition corresponding to the heating condition is calculated to move the cooler 6 and the displacement meter that also serves as the cooler moving mechanism. The mechanism 5 is controlled. In this cycle management, the cooling temperature of the heating unit is managed by the time until the displacement measurement is performed.

At the time of displacement measurement, the main controller 9 controls the displacement meter moving mechanism and receives displacement information at a predetermined position. The main controller 9 converts the obtained displacement information into a deformation amount,
The condition of the next heating bending cycle is determined by, for example, the algorithm described above. Fig. 6 (b) shows the cooler moving mechanism.
15 is a configuration example of a control system in a case where 15 is configured independently of the displacement meter moving mechanism 5.

FIG. 6C shows an example of the configuration of a control system having no cooler 6 for cooling the back surface of the heating section. The operation is almost equivalent to the case where the cooler 6 is not operated by the control system of FIG. Fig. 6 (d) shows a cooler for direct cooling of the heating section.
This is an example of a control system in the case where a cooling unit moving mechanism 13 for directly cooling a heating unit is provided. In this example, a heating unit direct cooling controller 11 is separately provided to control the heating unit direct cooling cooler 12 and the heating unit direct cooling cooler moving mechanism 13 according to the cooling temperature specified by the main controller 6. Here, the cooler 6 for backside cooling and the like and the control thereof are omitted, but it is of course possible to use the backside cooling together with the backside cooling without any problem.

In the above example, the main functions of the control system and the heating management are configured separately by the controllers.
Needless to say, it is not necessary to divide them in this way, and the control sharing of each controller does not need to be limited to the above-mentioned division.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A heating and bending apparatus shown in FIG.
And the displacement meter 4 were arranged in the positional relationship shown in FIG. 4, and the heating bending of the H-shaped steel was experimentally performed. Here, heater 2
As shown in FIG. 4 (a), a heater was disposed at a position 30 mm from the web surface and 25 mm from the lower surface of the flange, and was locally heated. The displacement meter 4 was fixed to the end so as to measure the displacement of the upper part of the flange surface on the burner side, and was arranged. Heater 2
Reciprocates in the longitudinal direction of the H-section steel 1 as shown in FIG. 4 (b), and local heating is performed. Here, no cooler is used.

The H-shaped steel applied was SM490Y H620 × 310 ×
It is 15 × 25 × 2500. In other words, web height 620mm, web thickness 15mm, flange width 310mm, flange thickness 25mm, length 25
It is an H-shaped steel of 00 mm. The heating rate of the heater is set to 600 mm / min, and the H-shaped steel is locally heated by reciprocating in a range of 1500 mm from the end in the longitudinal direction. The local heating is performed at a pitch of 5 minutes, and the heating is performed 7 round trips.

FIG. 5 shows the result of the bending by the local heating. The target value of the maximum temperature in this local heating is 750 ° C., and the minimum temperature is 295 ° C. FIG. 5 shows a state in which the deformation amount is cumulatively increased with this temperature change. The heating temperature by the local heating is substantially stable after the third time, and the maximum temperature and the minimum temperature are substantially constant.
At this time, the required processing amount, which is the amount of deformation (Δ) of the steel material, is 2.0 mm, and the processing amount after heating six times is about 1.6 mm.
0.4mm has not been reached. The deformation (δ) obtained in the sixth cycle is already stable and about 0.3 mm, so if the heating is applied only once (the seventh time), 1.9 mm
However, when the seventh straightening operation is completed, a processing amount of about 1.9 mm is obtained after air cooling.

This correction amount is sufficiently smaller than the range (target ± 0.2 mm) that is often required for quality assurance, and it has been confirmed that the correction can be performed with high accuracy.

[0039]

According to the present invention, accurate heating and bending can be easily performed. In addition, the amount of deformation per heating can be stabilized, and more accurate heating bending can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a configuration of a heating bending apparatus according to the present invention.

FIG. 2 is an explanatory diagram schematically illustrating a temperature distribution and a stress distribution of local heating, and FIG. 2A is an explanatory diagram illustrating a temperature distribution as contour lines. (B) is an explanatory view showing a stress distribution generated by the temperature gradient. (C) is explanatory drawing which shows typically the deformation | transformation of the steel material generate | occur | produced by the stress.

FIG. 3 is an explanatory diagram showing the progress of ratchet distortion accumulated by hysteresis of repeated distortion.

FIG. 4 is an explanatory diagram showing a positional relationship between a displacement meter and a burner with respect to an H-section steel, and (a) is an explanatory diagram viewed from the front. (B) is explanatory drawing seen from the side surface.

FIG. 5 is an experimental graph showing a state in which a steel material is temporally accumulated and deformed by repeated local heating.

FIG. 6 is a block diagram of a control system capable of automatically controlling a heating bending process. FIG. 6A is a configuration example of a control system suitable for a heating bending device, and FIG. (C) is a configuration example of a control system without a cooler for cooling the rear surface of the heating unit, and (d) is a configuration example of a control system when configured independently of the displacement meter moving mechanism. Is a configuration example of a control system in a case where a cooler for direct cooling of the heating unit and a cooler moving mechanism for direct cooling of the heating unit are provided.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 H-shaped steel 2 Heater 3 Heater moving mechanism 4 Displacement gauge 5 Displacement gauge moving mechanism 6 Cooler 7 Mounting stand 8 Controller 9 Main controller 10a Heating / cooling controller 10b Heating controller 11 Heating part direct cooling controller 12 Heating part direct cooling Cooler 13 Cooler moving mechanism for direct cooling of heating section 15 Cooler moving mechanism

Claims (8)

[Claims] 1. A heating and bending process for a steel material that locally deforms by heating the steel material, the heating and cooling of the steel material is repeated a plurality of times while measuring the shape of the steel material to obtain a target shape of the steel material. A method for hot bending a steel material, characterized by processing. 2. The method according to claim 1, wherein the heating temperature and the cooling temperature are kept constant in at least a part of the repeated heating and cooling. 3. A deformation amount δ of a steel material by one heating / cooling and a deformation amount Δ of a steel material required to obtain a target shape in any one of the above-mentioned repetitions of heating / cooling. Is measured, and the required number of remaining repetitions is calculated from the value of Δ / δ.
The heating and bending method according to claim 2, wherein heating and cooling are repeated at the same heating temperature and cooling temperature as the time when δ was measured. 4. The method according to claim 3, wherein the deformation amount δ is a value equal to or smaller than an allowable error range of a target shape. 5. A heating means for locally heating a predetermined position of a steel material, a heating means moving mechanism for moving the heating means in a predetermined pattern, and measuring at least one of a shape and a deformation amount of the steel material. An apparatus for heating and bending a steel material, comprising: a measuring means; and a measuring means moving mechanism for moving the measuring means following the movement pattern of the heating means. 6. A control device for automatically controlling the heating means, the heating means moving mechanism, the measuring means, and the measuring means moving mechanism according to a predetermined algorithm.
A heating and bending apparatus for a steel material according to claim 5. 7. A cooling means for locally cooling a back surface of a heating section of a steel material, and a cooling means moving mechanism for moving the cooling means in synchronization with a movement pattern of the heating means. A heating bending apparatus for steel material according to claim 5. 8. A cooling means for locally cooling a back surface of a heating section of a steel material, and a cooling means moving mechanism for moving the cooling means following a movement pattern of the heating means, wherein the control means is provided. 7. The apparatus according to claim 6, wherein the cooling means and the cooling means moving mechanism are also controlled.