JP5954300B2 - Clad metal plate manufacturing method and manufacturing apparatus - Google Patents

Description

  The present invention relates to a clad metal plate manufacturing method and a manufacturing apparatus for manufacturing a clad metal plate by sandwiching two sets of clad metal plates in a vertically symmetrical manner.

  In recent years, metal plates have been used as members of huge buildings such as bridges, buildings, ships, and marine structures. For this reason, the metal plate is required to have high corrosion resistance and corrosion resistance in order to ensure the safety of the building. For example, in offshore wind power generators that are showing increasing demand due to recent energy problems, a metal plate formed in a pipe shape is used as a structural member of the tower portion. Since the tower part has a structure based on the seabed, the metal plate always has a part in contact with seawater. For example, a stainless steel plate is used as a metal plate as a countermeasure against corrosion of the metal plate by seawater. However, if the entire tower portion is manufactured from the stainless steel plate, the cost increases.

  Therefore, metal plate manufacturers have reduced the use of parts that require corrosion resistance, such as parts that come in contact with seawater, that is, the outer peripheral part of the pipe is a stainless steel plate, and the inner peripheral part of the pipe that does not contact seawater is an inexpensive metal plate. We are trying to reduce costs. In this case, a clad pipe is used in which a clad metal plate formed by superposing two kinds of metal plates, a stainless steel plate and a metal plate, is formed into a pipe shape. The clad metal plate is manufactured through a process of rolling, cooling, and hot straightening by joining two kinds of metal plates made of a laminated material and a base material by vacuum welding or explosion bonding. Further, when the flatness of the clad metal plate after hot straightening is poor, cold straightening is performed.

  By the way, if the physical properties such as the yield stress and the linear expansion coefficient of the two types of metal plates forming the clad metal plate are different, shape defects such as warpage may occur during rolling or cooling. For this reason, a clad metal plate called a sand clad is used to manufacture a clad metal plate in which a clad metal plate obtained by superposing two kinds of metal plates as a set and the two sets of clad metal plates are vertically symmetrically arranged in a sandwich shape. Manufacturing methods may be used.

  When shipping a clad metal plate manufactured by sand clad, it is necessary to peel the sand clad metal plate in order to return it to a set of clad metal plates. The clad metal plate may be warped due to the residual stress distribution. If the height of the warp exceeds the shape inspection standard, re-correction of the clad metal plate is required, which causes problems such as an increase in manufacturing cost and delay in delivery. Here, the mechanism in which the residual stress that causes warping of the clad metal plate after peeling occurs in the manufacturing stage is as follows.

  That is, the clad metal plate thermally shrinks until the temperature of the clad metal plate after hot straightening reaches room temperature. Since the amount of thermal contraction of the clad metal plate varies depending on the linear expansion coefficient, in the case of a clad metal plate in which two metal plates having different linear expansion coefficients are overlapped, a residual stress is generated according to the amount of thermal contraction. For this reason, when manufacturing a clad metal plate in which two types of metal plates are joined, warpage due to residual stress or residual stress always occurs.

  From such a background, Patent Document 1 describes the linear expansion coefficient as the temperature difference between the upper and lower surfaces necessary to make the amount of warpage of a set of clad metal plates, which are a combination of two types of metal plates, at room temperature zero. It is calculated by the difference, the thickness of the base material and the laminated material, and the temperature on the hot correction inlet side, and the water flow density of the water cooling and cooling device provided in the hot straightening machine is controlled. A method of manufacturing a clad metal plate that prevents warping is described.

Japanese Patent Publication No.2-4374

  However, in a state where two sets of clad metal plates are vertically symmetrical and sandwiched, the upper and lower surfaces are the same metal plates and have the same linear expansion coefficient. It is not possible to apply temperature control according to the linear expansion coefficient of the type of metal plate. That is, according to the method described in Patent Document 1, it is not possible to prevent each clad metal plate from being warped when two sets of clad metal plates are peeled one by one.

  The present invention has been made to solve the above-described problems, and can suppress the occurrence of warpage in each clad metal plate when two sets of clad metal plates are peeled one by one. It aims at providing the manufacturing method and manufacturing apparatus of a clad metal plate.

In order to solve the above-described problems and achieve the object, a method for manufacturing a clad metal plate according to the present invention includes a set of clad metal plates in which a base material and a laminated material, which are two different types of metal plates, are overlapped, A method for manufacturing a clad metal plate, in which two sets of clad metal plates are symmetrically rolled, cooled, hot straightened, and cold straightened and then separated into two sets of clad metal plates. Then, when cold-correcting two sets of clad metal plates using a roller leveler, the thicknesses f _B and t _{C of the} base material and the laminated material are calculated as 2 using the function f shown in the following formula (1). Calculating a plastic deformation rate η in the second roll, and cold-correcting the two sets of clad metal plates so that the plastic deformation rate in the second roll becomes the calculated plastic deformation rate η. Features.

The method for producing a clad metal plate according to the present invention, in the above invention, when cold-correcting two sets of clad metal plates using a roller leveler, using the function f shown in the following formula (2), Plate thickness t _B , t _C , yield stress σ _{e, B} , σ _{e, C} , linear expansion coefficient α _B , α _C , Young's modulus E _B , E _C , and two sets of clad after hot correction The plastic deformation rate η in the second roll is calculated from the upper surface temperature T _SUR of the metal plate, and the two sets of clad metal plates are set so that the plastic deformation rate in the second roll becomes the calculated plastic deformation rate η. It includes the step of cold straightening.

In order to solve the above-described problems and achieve the object, the clad metal plate manufacturing apparatus according to the present invention includes a set of clad metal plates in which a base material and a laminated material, which are two different types of metal plates, are overlapped, A clad metal plate manufacturing apparatus for manufacturing a clad metal plate by separating the two sets of clad metal plates symmetrically in the vertical direction, rolling, cooling, hot straightening, and cold straightening, and separating them into two sets of clad metal plates Then, when cold-correcting two sets of clad metal plates using a roller leveler, the thicknesses f _B and t _{C of the} base material and the laminated material are calculated as 2 using the function f shown in the following formula (3). Means for calculating the plastic deformation rate η in the second roll and cold-correcting the two sets of clad metal plates so that the plastic deformation rate in the second roll is equal to the calculated plastic deformation rate η. Features.

  According to the method and apparatus for manufacturing a clad metal plate according to the present invention, it is possible to suppress the occurrence of warpage in each clad metal plate when two sets of clad metal plates are peeled one by one.

FIG. 1 is a cross-sectional view showing a configuration of a clad metal plate. FIG. 2 is a cross-sectional view showing the configuration of the sand clad metal plate. FIG. 3A is a front view showing the configuration of the roller leveler. FIG. 3B is a side view showing the configuration of the roller leveler. FIG. 4 is a diagram showing an example of a residual stress distribution in the thickness direction of the sand clad metal plate. FIG. 5 is a diagram showing an example of the relationship between the plastic deformation rate during correction of the sand clad metal plate and the warp height of the clad metal plate generated when the sand clad metal plate is peeled off. FIG. 6A is a diagram showing an example of a residual stress distribution in the thickness direction in the state of a sand clad metal plate when corrected at a plastic deformation rate of 70%. FIG. 6B is a diagram illustrating an example of a residual stress distribution of the upper half of the clad metal plate when corrected with a plastic deformation rate of 70%. FIG. 7A is a diagram showing an example of a residual stress distribution in the thickness direction in the state of a sand clad metal plate when corrected at a plastic deformation rate of 50%. FIG. 7B is a diagram illustrating an example of a residual stress distribution of the upper half clad metal plate when corrected at a plastic deformation rate of 50%.

  Warpage that occurs when two sets of clad metal plates, that is, sand clad metal plates are peeled off, is caused by the difference in linear expansion coefficient between the two types of metal plates that form the clad metal plate in the cooling process of the sand clad metal plate. This is due to the residual stress distribution in the direction. As shown in FIG. 1, the clad metal plate is formed by joining two types of metal plates made of a base material 1 and a laminated material 2 by vacuum welding or explosion bonding, rolling, cooling, hot straightening and cooling. It means a metal plate manufactured through a process such as straightening. In addition, the sand clad metal plate means a pair of clad metal plates that are sandwiched in a vertically symmetrical manner as shown in FIG.

  As a method of reducing the residual stress in the plate thickness direction of a metal plate, correction using a roller leveler is generally used, and it has been conventionally known that the amount of residual stress can be reduced by correcting with a high plastic deformation rate η. ing. Here, the plastic deformation rate η is the ratio of the plastic deformation area in the thickness direction of the metal plate when bending is applied by the second leveling roll from the entry side of the roller leveler, and the degree of bending at the roller leveler is expressed as follows. It is an index generally used as an index to represent.

  The roller leveler means an apparatus configured as shown in FIGS. 3A and 3B. 3A and 3B are a front view and a side view showing the configuration of the roller leveler, respectively. As shown in FIGS. 3A and 3B, the roller leveler 10 has a plurality of upper and lower leveling rolls 11U and 11D arranged in a staggered manner in the vertical direction along the pass line through which the steel sheet S passes, and the upper and lower leveling rolls 11U, The shape defect of the steel sheet S is corrected by repeatedly bending with 11D.

  The upper and lower leveling rolls 11U and 11D are supported by upper and lower backup rolls 12U and 12D, respectively, and the upper and lower backup rolls 12U and 12D are supported by integral upper and lower frames 13U and 13D. A plurality of wedges 14 are provided on the upper frame 13U along the width direction of the upper and lower leveling rolls 11U and 11D. The wedge 14 adjusts the amount of reduction in the width direction of the upper and lower leveling rolls 2U and 2D independently in order to adjust the deflection generated in the width direction of the upper and lower leveling rolls 11U and 11D by the correction reaction force.

  When the steel plate S is corrected using the roller leveler 10, the upper leveling roll 11U or the lower leveling roll 11D is tilted together with the frame, and the interval between the upper and lower leveling rolls 11U, 11D on the outgoing side is the upper and lower leveling rolls. The steel plate S is passed in a state narrower than the distance between 11U and 11D. The amount of reduction by the upper and lower leveling rolls 11U and 11D on the entry side and the exit side can be individually set by the entry and exit hydraulic cylinders 15 attached to the upper part of the roller leveler 10.

  However, in the case of a metal plate that has a non-uniform residual stress distribution in the thickness direction, such as a sand clad metal plate, the residual stress distribution that does not warp after correction may not be obtained depending on the magnitude of the plastic deformation rate η Therefore, it is not appropriate to simply correct based only on the plastic deformation rate η. Therefore, the inventors of the present invention calculated the residual stress after correction when a sand clad metal plate having residual stress before correction was corrected with various plastic deformation ratios η using a leveler analysis model, The warp height of the clad metal plate after peeling the metal plate was evaluated. The leveler analysis model used in this calculation is a slit model in which elements are divided in the plate thickness direction and plate width direction, and is used to analytically solve the repeated bending deformation behavior of each element. Stress is calculated and converted to warp height.

  As an example of the calculation, the table below shows the plate thickness, yield stress, Young's modulus, linear expansion coefficient, the upper surface temperature of the clad metal plate after hot straightening, and the interface temperature between the base material and the laminated material, respectively. The residual stress distribution in the plate thickness direction was calculated when the metal plate under this condition was at room temperature (25 ° C.). The calculation results are shown in FIG. Here, in FIG. 4, the plus sign residual stress indicates the tensile residual stress, and the minus sign residual stress indicates the compressive residual stress. Then, the residual stress after correction of the sand clad metal plate was calculated using the calculated residual stress in the thickness direction as input data, and the warp height of the clad metal plate was calculated from the residual stress distribution of the clad metal plate after peeling. .

  FIG. 5 shows the warpage height of the clad metal plate that occurs when the sand clad metal plate after correction is peeled off when it is corrected at various plastic deformation rates η. As shown in FIG. 5, the warp height of the clad metal plate generated after peeling differs depending on the plastic deformation rate η, and the plastic deformation rate η of 70% or 80% that has been considered to be effective for reducing the residual stress until now. Then, a large warp of 44 mm / 5 m or more (44 mm warp height per 5 m plate length) occurred. Further, it was confirmed that there is a plastic deformation rate η (about 50% in the example of FIG. 5) that minimizes the warp height.

  FIG. 6A shows the residual stress distribution in the thickness direction in the state of the sand clad metal plate when corrected with a plastic deformation rate of 70% at which the warp height after peeling becomes 44 mm / 5 m, and FIG. The residual stress distribution of the clad metal plate of the upper half of the sand clad metal plate is shown later. Further, FIG. 7A shows the residual stress distribution in the thickness direction in the state of the sand clad metal plate when the warp height after peeling is 1 mm / 5 m and the plastic deformation rate is corrected to 50% which is the minimum in all conditions. FIG. 7B shows the residual stress distribution of the clad metal plate in the upper half of the sand clad metal plate after peeling.

  Warpage of the clad metal plate after peeling is caused by residual stress distribution. When a sand clad metal plate having a residual stress distribution as shown in FIG. 4 is peeled off, taking the upper half of the sand clad metal plate as an example, the residual stress distribution of the upper surface is tensile residual stress and the lower surface is compressive residual stress. Therefore, the clad metal plate after peeling becomes warped. In order to prevent warpage of a clad metal plate having such a residual stress distribution, a large bending strain is applied to the sand clad metal plate, and the center of the plate thickness where a large compressive residual stress is applied is yielded to remain. What is necessary is just to make stress as small as possible. However, in the correction by the roller leveler, the maximum value of the plastic deformation rate η is about 80 to 70% due to restrictions such as load resistance. For this reason, a bending strain cannot be applied to the center portion of the plate thickness, and a residual stress almost equal to that before correction remains in the center portion of the plate thickness.

  Therefore, as a result of intensive studies, the inventors of the present invention have made a residual stress warpage by applying a tensile residual stress of the same magnitude in the vicinity of the region where the compressive residual stress distribution is acting. It has been found that the influence on can be counteracted. Then, the inventors of the present invention analyze the residual stress after correction in consideration of this knowledge, and in this calculation example, the warp height of the clad metal plate is set by setting the plastic deformation rate to 50%. I was able to minimize it. On the other hand, when the plastic deformation rate is set to 70%, the region in which the tensile residual stress is applied is small in the vicinity of the region in which the compressive residual stress is applied, resulting in a large warp in the clad metal plate. It became. From these results, the best mode for setting the roller leveler correction condition so that the warp does not occur when the sand clad metal plate is peeled or the warp height is minimized has been conceived.

In order to apply this knowledge to actual operations, the residual stress (in the case of this calculation example, compressive residual stress) acting on the laminated material is applied to the base metal by the same distance in the thickness direction as the residual stress ( In the case of this calculation example, a desired residual stress distribution can be obtained by applying a residual tensile stress) and leaving the residual stress that was held before correction. In other words. It is necessary to set correction conditions so that bending strain is not applied to the base material region within the same range of distance in the thickness direction as the residual stress acting on the laminated material. That is, the plastic deformation rate η may be determined using the function f shown in the following mathematical formula (3). Here, in Equation (3), t _B is the thickness of the base metal, t _C denotes the thickness of the mating member.

However, the optimum plastic deformation rate η is expressed by Equation (4) according to the thickness of the base material and the laminated material, the yield stress, the linear expansion coefficient, the Young's modulus, and the upper surface temperature of the sand clad metal plate after hot straightening. The plastic deformation rate η determined by the function f shown may be slightly different. For this reason, it becomes possible to calculate the optimum plastic deformation rate η by adding correction to the plastic deformation rate η determined by the function f shown in Equation (4) according to the conditions of these sand clad metal plates, A clad metal plate that does not warp after peeling can be produced. That is, the plastic deformation rate η for preventing the clad metal plate from being warped can be expressed by a function f shown in the following formula (5). Here, in Equation (5), σ _e is the yield stress, α is the linear expansion coefficient, E is the Young's modulus, T _SUR is the upper surface temperature of the sand clad metal plate, the subscript B is the base material, and the subscript C is Represents laminated material.

  From the above, the flow of the manufacturing method of the clad metal plate according to the present invention is as follows. That is, in the method for producing a clad metal plate according to the present invention, first, the thickness, yield stress, Young's modulus, linear expansion coefficient, and sand clad after hot correction of the two types of metal plates forming the clad metal plate. Using the upper surface temperature of the metal plate, a plastic deformation rate η that minimizes the warpage that occurs when the two sets of clad metal plates are peeled after correction is calculated. Then, the second reduction amount from the entrance side of the roller leveler is set so that the plastic deformation rate during correction becomes the calculated plastic deformation rate η, and the sand clad metal plate is passed through the roller leveler. As a result, a clad metal plate that does not undergo treatment when peeled or has a small warp height can be produced.

  Applying the manufacturing method of the present invention and the conventional manufacturing method, a sand clad metal plate manufactured by combining clad metal plates made of two types of metal plates having different linear expansion coefficients is corrected, and the sand clad metal plate is peeled off. The warp height of the clad metal plate after measurement was measured. The metal plate used for the test has carbon steel as the base material and titanium alloy as the laminated material, and has physical property values shown in Table 2 below. Then, these metal plates were vacuum welded, and two sets of clad metal plates were combined to form a sand clad metal plate, and a clad metal plate was manufactured through processes of rolling, cooling, hot straightening, cold straightening, and peeling. The temperature of the metal plate after hot straightening was 347 ° C. for the base material. Here, the plate | board thickness of the laminated material and base material which are shown in Table 2 has shown each thickness in the clad metal plate after peeling.

  Next, after naturally cooling the sand clad metal plate to room temperature, a plastic deformation rate of 50% (Example 1), in which the warp height after peeling is predicted to be minimum from the above formula (5), the above formula. The sand clad metal plate was corrected at a plastic deformation rate of 65% (Example 2) calculated from (4) and a plastic deformation rate of 70% (Comparative Example) for comparison. After the correction, the sand clad metal plate was peeled into a pair of clad metal plates by gas cutting, and then the clad metal plate was placed on a surface plate, and the warp height of the clad metal plate was measured using a scale. Table 3 below shows the warpage height after peeling of the sand clad metal plate corrected at each plastic deformation rate.

  As shown in Table 3, the warp height of the clad metal plate after peeling was 1 mm / 5 m (plate length) under the condition of the plastic deformation rate of 50% in Example 1 where the warp height was predicted to be minimized by calculation. The warp height of the clad metal plate after peeling is 3 mm / 5 m (3 mm warp height per 5 m plate length), which satisfies the shape inspection standard. It was. On the other hand, under the condition of a plastic deformation rate of 70%, the warp height of the clad metal plate after peeling was as large as 44 mm / 5 m (44 mm per 5 m plate length), and did not satisfy the shape inspection standard. . From the above, it was confirmed that the warp height of the clad metal plate after peeling the sand clad metal plate can be reduced by the production method of the present invention.

  As mentioned above, although the embodiment to which the invention made by the present inventors was applied has been described, the present invention is not limited by the description and the drawings constituting a part of the disclosure of the present invention according to this embodiment. What comprised each component suitably was also included in this invention. That is, other embodiments, examples, operation techniques, and the like made by those skilled in the art based on this embodiment are all included in the scope of the present invention.

10 Roller Leveler 11U Upper Leveling Roll 11D Lower Leveling Roll 12U Upper Backup Roll 12D Lower Backup Roll 13U Upper Frame 13D Lower Frame 14 Wedge 15 Hydraulic Cylinder S Steel Plate

Claims (3)

Rolling, cooling, hot straightening, and cold straightening were performed with a pair of clad metal plates in which two different types of metal plates, ie, a base metal and a laminated material, were superposed, and the two pairs of clad metal plates were vertically symmetrical. Thereafter, a clad metal plate manufacturing method for manufacturing a clad metal plate by separating into two sets of clad metal plates,
When cold-correcting two sets of clad metal plates using a roller leveler, the second roll from the thicknesses t _B and t _{C of the} base material and the laminated material using the function f shown in the following formula (1) And a step of cold-correcting two sets of clad metal plates so that the plastic deformation rate η of the second roll is equal to the calculated plastic deformation rate η. A method for producing a metal plate.

When cold-correcting two sets of clad metal plates using a roller leveler, the thicknesses t _B and t _{C of} the base material and the laminated material, yield stress σ _{e, B} , σ _{e, C} , linear expansion coefficients α _B , α _C , Young's modulus E _B , E _C , and plastic deformation in the second roll from the top surface temperature T _SUR of the two sets of clad metal plates after hot correction The method includes the step of cold-correcting the two sets of clad metal plates so that the rate η is calculated and the plastic deformation rate at the second roll is equal to the calculated plastic deformation rate η. The manufacturing method of the clad metal plate of description.

Rolling, cooling, hot straightening, and cold straightening were performed with a pair of clad metal plates in which two different types of metal plates, ie, a base metal and a laminated material, were superposed, and the two pairs of clad metal plates were vertically symmetrical. Thereafter, a clad metal plate manufacturing apparatus for manufacturing a clad metal plate by separating into two sets of clad metal plates,
When cold-correcting two sets of clad metal plates using a roller leveler, the second roll from the thicknesses t _B and t _{C of the} base material and the laminated material using the function f shown in the following formula (3) And a means for cold-correcting two sets of clad metal plates so that the plastic deformation rate η of the second roll is equal to the calculated plastic deformation rate η. Metal plate manufacturing equipment.

Images