JPS61193703A - Preventing method for camber of two-layers clad metallic plate - Google Patents

Abstract

PURPOSE:To straighten surely the camber of a two-layers clad metallic plate consisting of a base metal and cladding metal by cooling forcibly the metal side of the metallic plate where the rate of thermal shrinkage is larger upon ending of the rolling of said plate then straightening the plate by rolls. CONSTITUTION:A radiation thermometer 12 measures the temp. on the top and bottom surfaces of the clad steel plate 1 upon ending of the rolling of the plate 1 by a rolling mill 10 and the result thereof is transmitted to a controller 15. The controller 15 detects the rate of the thermal shrinkage arising in the base metal of the base metal temp. Tc during the time until said metal attains the ordinary temp. according to the coefft. of linear expansion on the base of the base metal temp. Tc of the plate 1 and determines the cladding metal temp. Ts of the cladding metal at which the rate of thermal expansion equal to such rate of the thermal expansion arises until the cladding metal attains the ordinary temp. The controller calculates further the cooling water flow rate and work roll speed necessary for cooling forcibly the metallic side where the rate of the thermal shrinkage is higher so as to generate the temp. difference Tc-Ts between the base metal and cladding metal of the plate 1. A flow rate control valve 14 and work rolls 10A are driven and controlled in accordance with the result of such calculation by which the straightening of the clad steel plate 1 is repeated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for preventing warpage of a 2N clad metal plate.

[Prior Art] Even if a two-layer clad steel plate, etc. made of a composite material such as stainless steel or cupronickel and a base material such as carbon steel is flat at the end of rolling, as the temperature of the steel plate decreases thereafter, Distortion or warping occurs in the width direction and length direction of the board. That is, as shown in FIG. 2, the clad steel plate 1 is made up of two plate materials IA and IB having different coefficients of linear expansion. Therefore, when the steel plate 1 undergoes a cooling process, the steel plate 1 is bent so that the plate material IA, which has a large coefficient of linear expansion and a large amount of shrinkage, is on the inside, causing distortion or warping.

In response to this problem, the present applicant has proposed a method for straightening the warpage of a two-layer clad steel sheet as disclosed in Japanese Patent Application Laid-Open No. 59-42122, and has achieved results.

That is, the method according to JP-A-59-42122 is as follows:
When straightening a rolled clad steel plate in a hot straightening machine, by forcibly cooling the steel plate side with a large amount of heat shrinkage before or during hot straightening, the temperature difference between the side of the steel plate with a large amount of heat shrinkage and the side of the steel plate with a small amount of heat shrinkage is created. This causes a state in which the same amount of warpage as after cooling occurs, and then the product in this state is flattened using a hot leveler or the like, thereby making it possible to prevent warpage after cooling to room temperature.

[Problems to be Solved by the Invention] However, in reality, the clad steel sheet warps immediately after rolling is completed. Therefore, while the steel plate is being delivered from the rolling mill to the hot straightening machine, there are problems such as bumps between the conveyor table rollers due to the above-mentioned warping, roller flaws due to such troubles, and frequent downtime. arise.

An object of the present invention is to perform reliable warpage correction immediately after rolling is completed.

[Means for Solving the Problems] The key to preventing warping of a two-layer clad metal plate according to the present invention is to thermally shrink the two-layer clad metal plate consisting of a base material and a laminate material after rolling the metal plate. By forcing the metal side with the larger amount to cool, the metal plate is heated to +E by the rolls of a rolling mill under conditions that create a temperature difference between the two metals corresponding to the difference in linear expansion coefficients of both metals. It was designed to do so.

[Function] According to the present invention, a rolling mill is used as a straightening means, and the metal side having a large amount of heat shrinkage is forcibly cooled before or during straightening by the rolling mill, so that the same amount of warpage as after cooling is realized in advance. By flattening this 7g product with the rolls of a rolling mill under such conditions, it becomes possible to reliably straighten the warpage immediately after rolling is completed.

[Embodiment] FIG. 1 is a control system diagram showing an embodiment of the present invention. In FIG. 1, 10 is a rolling mill, IOA is a work roll,
IOB is a backup roll, and ll is a table roller. Radiation thermometers 12 are installed at the entrance and exit sides of the rolling @ 10 to measure the temperature of the upper and lower surfaces of the clad steel plate l.
are installed before and after the rolling mill 10, and a ladder 1 is connected to a sprayer that supplies cooling water to the upper and lower surfaces of the clad steel plate 1.
3 is installed. 14 is a flow control valve that adjusts the amount of cooling water supplied from the spray header 13, and 15 is a controller to be described later.

After the rolling of the clad steel plate 1 by the rolling mill IO is completed,
The radiation thermometer 12 measures the temperature of the upper and lower surfaces of the clad steel plate l, and transmits the measurement results to the controller 15. Controller 15
is the base material temperature T of the clad steel plate 1, as shown in FIG.
Based on c, this!・Ascertain the amount of thermal contraction ΔεC that occurs while the base material at J material temperature Tc reaches room temperature according to the coefficient of linear expansion, and calculate the thermal acid 1i equivalent to this thermal contraction fΔεC! The laminate material temperature Ts of the laminate material that will occur until the amount ΔεS reaches room temperature is determined. Furthermore, the controller 15 controls the temperature difference (
The amount of cooling water and work roll speed (cooling time) required to forcibly cool the metal side with a large amount of thermal contraction so that Tc-Ts) occurs between the base material and the laminate of the clad steel sheet 1.
Calculate. The controller 15 drives and controls the flow rate control valve 14 and the work roll IOA based on the calculation result described in , so that the base material is at a temperature Tc and the laminated material is at a temperature Ts.
The work roll IOA is driven in reverse while the clad steel plate 1 is restrained by the work roll IOA, and the straightening of the clad steel plate 1 by the work roll 10A is repeated.

Here, since the clad steel plate l that is straightened as described above has already been finished to the product thickness, the work roll IOA
The straightening is performed under conditions where the roll opening degree of the work roll IOA is set to a total thickness of about 12 to 3 mm of the clad steel plate l without applying any rolling reduction.

In addition, there is a temperature difference (T c - Ts) between the base material and the laminated material.
The forced cooling to produce this may be completed before the restraint straightening of the clad steel plate 1 by the work roll IOA, or may be completed during the restraint straightening of the clad steel plate 1 by the work roll IOA.

According to the above embodiment, the rolling mill 10 is used as a straightening means, and the metal side having a large amount of heat shrinkage is forcibly cooled before or during straightening by the rolling mill 10, so that the same amount of warpage as after cooling is prevented. By straightening the workpiece in this state to be flat with the work roll IOA under the actual state, it becomes possible to reliably straighten the warp immediately after rolling is completed. This makes it possible to prevent subsequent warpage, and to avoid troubles such as bumping between conveyor table rollers during line conveyance.

Hereinafter, specific implementation results of the present invention will be explained. The laminated material is stainless steel, the base material is carbon steel, and the total thickness of the plate is 20 mm.
m+a, cladding ratio (thickness of laminate/total thickness of board) 30%
The present invention was applied to a stainless clad steel plate. That is, immediately after hot rolling the stainless clad steel sheet, a temperature difference corresponding to the difference in the amount of heat shrinkage between the base material and the laminate is applied between the two metals, and the steel sheet is reverse restrained by rolling rolls. Corrected. At this time, since the rolling end temperature of the steel plate was 700°C, it became clear from Figure 3 that the temperature difference between the base material and the laminate should be set to 12G''0. As shown in Figure 1,
The roll opening of the rolling mill was set to 22 layers, and while only the stainless steel side of the clad steel plate was cooled by spray lag, correction was performed by reverse restraint of 3 baths. As a result of the above-mentioned correction, the occurrence of subsequent warpage could be suppressed to almost zero, and it was recognized that the present invention is extremely effective in preventing warpage of clad steel sheets.

[Effects of the Invention] As described above, the method for preventing warping of a two-layer clad metal plate according to the present invention reduces the amount of heat shrinkage of the two-layer clad metal plate consisting of a base material and a laminate after the rolling of the metal plate is completed. The metal plate is straightened by the rolls of a rolling mill under a condition where the larger metal side is forcedly cooled to create a temperature difference between the two metals corresponding to the difference in linear expansion coefficients of the two metals. It is.

Therefore, it is possible to reliably straighten the warp immediately after rolling is completed.

[Brief explanation of the drawing]

Fig. 1 is a control system diagram showing one embodiment of the present invention, Fig. 2 is an end view showing the state of warping of a two-layer clad steel plate, and Fig. 3 is a heat treatment of the base material and laminated material of the two-layer clad metal plate. FIG. 3 is a diagram showing the difference in shrinkage amount. l... Clad steel plate, IA, IB... Plate material, lO・
...Rolling mill, IOA...Work roll, 12...Radiation thermometer, 13...Ladder to spray, 14...Flow control valve, 15...Controller. Agent Patent Attorney Osamu Shiokawa Figure 1 1 ----') 5 ! IfI I
3-=----Spray-) Goo 1 rolling----
-Rolling tower +4-----First flow control valve +0
A----Work roll + 5-=-1 controller + 2-------1 radiation thermometer 2nd figure Δε (%) Temperature

Claims (1)

[Claims] (1) After rolling a two-layer clad metal plate consisting of a base material and a laminate material, by forcibly cooling the metal side of the metal plate with a large amount of thermal contraction, the coefficient of linear expansion of both metals can be reduced between the two metals. A method for preventing warpage of a two-layer clad metal plate, in which the metal plate is straightened by the rolls of a rolling mill under conditions that produce a temperature difference corresponding to the temperature difference.