JPS61159221A - Camber straightening method of double layer cladding metal sheet - Google Patents

Abstract

PURPOSE:To control the camber generation in the room temp. of various kinds double layer cladding metal sheets by deciding with using an equation the temp. difference in both metallic sheets based on the factor to influence a camber generation before the hot straightening or during the hot straightening of a double layer cladding metallic sheet. CONSTITUTION:A hot straightening is performed by causing the temp. difference DELTAT shown by equation I between both metals by forcibly cooling the metal side of larger shrinkage before the hot straightening of during the hot straightening of a double layer cladding metal sheet. It is taken in the equation that DELTAalpha: difference in the linear expansion coefficient of both metals, a: cladding ratio (thickness of cladding material/total thickness of plate), T0: inlet side temp. deg.C of hot straightening, -alpha: average linear expansion coefficient of both metals.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for straightening warpage of a two-layer clad metal plate.

[Prior Art] Conventionally, when manufacturing a two-layer clad metal plate such as a two-layer clad steel plate where the laminating material is stainless steel, cupronickel, etc. and the material is carbon steel, there is a difference in linear expansion coefficient of the art materials. There was a problem in that there was a difference in the amount of thermal shrinkage between the two materials after straightening with a hot leveler, and after cooling to room temperature, warping occurred with the member with the larger amount of shrinkage on the inside.

In response to this, the present inventors have developed a method for straightening the warpage of double-layer clad steel sheets as shown in Japanese Patent Application Laid-Open No. 59-42122, and have achieved
I have achieved results.

That is, the method according to JP-A-59-42122 is as follows:
By forcibly cooling the steel plate side with a larger amount of heat shrinkage before or during hot straightening, a temperature difference is created between the side of the steel plate with a smaller amount of heat shrinkage, and the same amount of warp as after cooling is created in advance. This method makes it possible to prevent the steel plate from warping after being cooled to room temperature by flattening the steel plate using a hot leveler or the like.

According to this method, the steel plate immediately after hot straightening will be warped in the opposite direction due to soaking, but after that, this warp will decrease due to the difference in the amount of heat shrinkage during cooling, and at room temperature At times, a nearly flat state can be obtained. Therefore, it is possible to reduce the burden of cold straightening after cooling and to omit the cold straightening process.

[Problems to be solved by the invention] However, the two-layer clad steel plate that actually undergoes straightening,
It is not a single type of thing, but a plate thickness, plate width, cladding ratio (=
The material of the laminate (laminated material thickness/plate thickness) and the material of the laminate are variously different. Therefore, when carrying out the method according to JP-A-59-42122, when straightening a steel plate by simply creating a temperature difference between the front and back surfaces, although there are cases where the warpage is completely eliminated, the amount of warpage correction is insufficient. Problems arise such as there are cases where warpage remains, and cases where the amount of warpage correction is too large and warpage occurs in the opposite direction.

The present invention calculates the necessary and appropriate temperature difference to straighten various two-layer clad metal plates so that they are flat at room temperature, and reliably prevents warping of the metal plates at room temperature.
- The purpose is to provide a method that makes it possible.

[Means for Solving the Problems] The present invention provides a method for straightening warpage of a two-layer clad metal plate consisting of a base material and a laminate, in which heat shrinkage is performed before or during hot straightening of the two-layer clad metal plate. By forcing the metal side with the larger amount to cool, the following temperature difference Δ is created between the two metals.
T, that is, △T= J (△α, a, a, To) However, 608 Difference in linear expansion coefficient of both metals a: Cladding ratio (thickness of laminated material/total thickness of plate) T0: Hot straightening entry side Temperature (°C) Hot straightening is performed by bringing about the average coefficient of linear expansion of the metal.

[Function] According to the present invention, the temperature difference to be applied to the two-layer clad metal plate is determined based on changes in factors that affect the occurrence of warpage of the two-layer clad metal plate, and the room temperature of various two-layer clad metal plates is determined. This makes it possible to reliably suppress the occurrence of warpage in.

[Example] Figures 1 (A) to (D) show plates with a thickness of 20 mm and a width of 300 mm.
A stainless clad steel plate of 0.011m was selected as a representative example of a two-layer clad metal plate, and the difference Δα in the II expansion coefficient of the base metal made of carbon steel and the laminated metal made of stainless steel, and the average linear expansion of both metals were determined. Among the four conditions: ratio i, cladding ratio (thickness of cladding material/total thickness of plate) a, and hot straightening entrance temperature TO, for the material where one condition is changed with the other conditions as the standard condition. 2 shows the results of hot straightening using the apparatus shown in FIG. 2 while changing the temperature difference ΔT between the front and back surfaces of both metals using a water cooling apparatus. Note that the standard conditions are Δα=Q, 4X10(
1/'C), a= L, S xlO(1/'0), a=
0.3, T0: 400°C. In the figure, the "x" mark indicates that there is warpage at room temperature (warp with metal with a large coefficient of linear expansion on the inside), and the mark "10" indicates that there is reverse warpage (warp with a large coefficient of linear expansion) at room temperature. This indicates that there is a warpage (with the metal facing outward), and the "0" mark indicates that it is approximately flat at room temperature. As can be seen from Figure 1, in order to make the final amount of warpage at room temperature zero, the temperature difference △T between the front and back surfaces applied during hot straightening must be adjusted according to the following (1).
It must be given as a function shown in the formula.

ΔT=1(Δα, τ, a, To)...(1)
Difference in coefficient of linear expansion of 608 metals, average of 52 metals! ! Expansion coefficient a: Cladding ratio (thickness of laminated material/total thickness of plate) TO: Hot straightening entrance temperature For example, when estimating the function of equation (1) from Fig. 1 (A) to (D), ΔT=, Δα (temperature difference is proportional to the linear expansion coefficient difference between both metals) = to 21/a (temperature difference is reversible to the average linear expansion coefficient of both metals) = k3a (1a) (temperature difference is expressed as a quadratic function of the cladding ratio) = K4 T O (the temperature difference is proportional to the hot straightening entrance temperature) (4 is a proportionality constant for k+ ~), so 1
Expressed using two equations, the following equation (2) is obtained.

△T=ko 5-=fa a (1-a) *To-
(2) Here, ko for making the steel plate substantially flat at room temperature has a value of "4 to 6" from FIG.

However, ko in the range where the effect of this method exists, that is, the range in which the final amount of warpage can be made smaller than the final amount of warpage when this method is not used at all, may be a value of "1 to 11". Note that the above equation (2) is just a 1 composed of each factor.
A method of controlling the temperature difference using an equation including these factors in addition to this equation is included within the scope of the method of the present invention.

Note that FIGS. 1(A) to (D) are for stainless clad steel plates as representative examples of two-layer clad metal plates; however, according to the present inventor, FIGS. 1(A) to (D) D
) is widely recognized to hold true in general two-layer clad metal plates.

Further, in FIG. 2, 1 is a clad steel plate, 2 is a hot leveler roll, and 3 is a cooling device.

Hereinafter, specific implementation results for stainless clad steel will be explained. Plate thickness 20III11, plate width 3000
A conventional method of hot straightening stainless clad steel with a mm clad ratio of 10.30.50% using the apparatus shown in Figure 2 to maintain a constant temperature difference between the front and back surfaces regardless of the clad ratio; Using the relational expression shown in equation (2), which is one of the estimation functions of equation (1), the temperature difference between the front and back surfaces is controlled to perform hot straightening. I made a comparison. In the conventional method, the temperature at the entrance of the hot leveler was 700°C, but with cladding ratios of 10 and 30.50%, hot straightening was performed at 500°C on the stainless steel side and 800°C on the carbon steel side by cooling the stainless steel side on one side. It ended and became flat. On the other hand, in the method of the present invention,
The temperature difference between the front and back surfaces is controlled according to equation (2), and at a cladding ratio of 10%, the stainless steel side is 580°C and the carbon steel side is 580°C.
□ At 820°C and 30% cladding ratio, hot straightening is completed at 500°C on the stainless steel side and 600°C on the carbon steel side. At 50% cladding ratio, hot straightening is completed at 460°C on the stainless steel side and 580°C on the carbon steel side. It became flat. Changes in the amount of warpage over time after straightening and the temperature difference between the front and back surfaces of the steel sheet immediately after straightening are shown in FIG. 3 for the method of the present invention and in FIG. 4 for the conventional method. In the conventional method, the temperature difference between the front and back surfaces during straightening of each steel plate was the same, so the amount of warpage caused by soaking the front and back surfaces (the amount of warpage after about 1 minute in the figure) was also different for the three cladding ratios. They are approximately the same - and the amount of warpage is approximately 180 am. However, the subsequent change in warpage due to the difference in thermal expansion coefficient between stainless steel and carbon steel differs depending on the cladding ratio, and the final amount of warpage was approximately zero at a cladding ratio of 30%, but when the cladding ratio At 1O%, 1001 of the warpage caused by single-sided cooling straightening remains, and at a cladding ratio of 50%, the warpage due to the difference in thermal expansion coefficient between the two steel materials is large, and the warpage in the opposite direction from the top is 35mm. Occurred.

On the other hand, in the method of the present invention, the temperature difference between the front and back surfaces is changed depending on the cladding ratio, so the amount of warpage caused by soaking the steel materials on the front and back surfaces (the amount of warping after about 1 minute in the figure) is less than 1 minute after the cladding ratio.
The warpage amount is 70 mm at 0%, 180 mm at 30% cladding ratio, and 210 mm at 50% cladding ratio. Therefore, the final amount of warpage was approximately zero regardless of the cladding ratio.

According to the present invention, as is clear from the above-mentioned practical results, by controlling the temperature difference between the front and back surfaces using the relational expression (2) and hot straightening, the plate thickness cladding ratio (- Laminated material thickness/plate thickness) Even if the materials of the laminated materials, the straightening start temperature, etc. are different, it is possible to obtain a flat two-layer clad steel plate without warping after cooling. For this reason, it has become possible to omit the cold straightening process that is performed after cooling for all two-layer clad steel plates.

It is clear that the present invention can be applied to two-layer clad metal plates made of any combination of different metals having different coefficients of thermal expansion in principle, and is not limited to clad steel plates.

[Effects of the Invention] As described above, the present invention provides a method for straightening warpage of a two-layer clad metal plate consisting of a base material and a laminated material, in which hot straightening of a two-layer clad metal plate or heat straightening during hot straightening is performed. By forcedly cooling the metal side with a large amount of contraction, the following temperature difference ΔT between the two metals, that is, ΔT = 1 (Δα, 10,000, a, To), where Δα; linear expansion of both metals Difference in rate a: Cladding ratio (thickness of laminate/total thickness of plate) TO: Hot straightening entry temperature (°C) Hot straightening is performed by creating the average m and w elongation of each two metals. This is how it was done. Therefore, it is possible to calculate the necessary and appropriate temperature difference to straighten various two-layer clad metal plates so that they are flat at room temperature, and to reliably prevent the metal plates from warping at room temperature. Become.

[Brief explanation of the drawing]

Figure 1 (A) is a diagram showing the relationship between the linear expansion coefficient difference between the two metals, the temperature difference between the front and back surfaces, and the final warpage, and Figure 1 (B) is the relationship between the average linear expansion coefficient of both metals and the temperature between the front and back surfaces. A diagram showing the relationship between the differential cladding ratio, the temperature difference between the front and back surfaces, and the final warpage; FIG. 1 (D) is a diagram showing the relationship between the hot straightening entrance temperature, the temperature difference between the front and back surfaces, and the final warpage; Fig. 2 is a schematic diagram showing the straightening device used in the implementation of the present invention, Fig. 3 (A) is a diagram showing the change over time in the amount of warpage after correction by the method of the present invention, and Fig. 3 (B) is a diagram showing the straightening device used in the practice of the present invention. Diagram showing the temperature difference between the front and back surfaces after straightening by the invention method, Figure 4 (A
) is a diagram showing the change over time in the amount of warpage after straightening by the conventional method, and FIG. 4(B) is a diagram showing the temperature difference between the front and back surfaces during straightening by the conventional method. 1... Clad steel plate, 2... Hot leveler roll, 3... Cooling device. Agent Patent Attorney Osamu Shiokawa Figure 1 (A) Figure 1 (B) Average of both metals Tosho Zhang Jiyaku Figure 1 (C) Both cladding materials (all of the electrical panel of the laminated material, 1) cL Early drawing 1 (
D) Both hot straightening entrance temperature TO (''C) Figure 2 Figure 3 (A) Hours (minutes) Figure 3 CB) Lunar baldness itJ To 20 30 40 S. Figure 4 (A) Hours 8t (minutes) Figure 4 CB) Light T t J1

Claims (1)

[Claims] (1) In a method for straightening warpage of a two-layer clad metal plate consisting of a base material and a laminate material, by forcibly cooling the metal side with a large amount of heat shrinkage before or during hot straightening of the two-layer clad metal plate. , the temperature difference ΔT shown below between both metals,
That is, ΔT=f (Δα, @α@, a, T_0) where, Δα: Difference in coefficient of linear expansion of both metals a: Cladding ratio (thickness of laminate/total thickness of plate) T_0: Hot straightening entrance temperature (°C) @α@: A method for straightening warpage of a two-layer clad metal, characterized by performing hot straightening by creating an average linear expansion coefficient of both metals.