JPH0255619A - Straightening method for flatness of metallic plate - Google Patents

Abstract

PURPOSE:To strainghten the flatness of a metallic plate such as a stainless steel plated by using graphite plates free from strain at a high temperature as a surface plate and pressing the whole body of target metallic plate between an upper and a lower surface plate. CONSTITUTION:A target metallic plate 1 such as a stainless steel plate to be straightened in flatness using two graphite plates as the surface plates is arranged horizontally while it is inserted between the upper and the lower side. Besides, to remove the ununiformity of temperature by the place of the metallic plate, steel plates 4 excellent in thermal conductivity are put on both sides or on a single side of the target metallic plate 1. To prevent the steel plates 4 or the graphite plates 3 from seizing on the target metallic plate 1, heat- resistant thin sheets 2 having a thinly formed oxide film and containing Al or Si are put on both sides of the target metallic plate. Besides, all these materials are heated using heat-insulating material 5 uniformly at temperatures higher than the restoring temperature of the target metallic plate 1 to remove the strain at a flat state and then to be cooled. Consequently, the flatness of the metallic plate such as stainless steel plate can be straightened.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for correcting the flatness of a metal plate such as a stainless steel plate.

(Prior art and its problems) Stainless steel is often used as a press plate, and a plate with good flatness is therefore required.

In addition, plates with high flatness are often required for special processing methods of metal plates or as parts of precision equipment.

However, it is quite difficult to obtain a plate with good flatness. For example, polishing is difficult because it causes distortion due to polishing heat and changes in internal distortion, while rolling can only achieve a certain degree of flatness, and internal distortion remains in the plate thickness. In order to remove internal distortion and achieve flatness, it is possible to heat the plate to a high temperature and cool it after removing the distortion, but it is currently difficult to obtain a flat plate because it is difficult to cool the plate uniformly. It is.

The inventors considered that a flat plate could be obtained by removing distortion by heating in a flat state and then cooling distortion without generating it, and as a result of intensive research into a method to eliminate the occurrence of cooling distortion, the inventors discovered the method. Heading: This completes the invention.

(Structure of the Invention) The gist of the present invention is a method for straightening the flatness of a metal plate as follows.

1. Using two graphite plates as a surface plate, place the metal plate whose flatness is to be corrected horizontally so as to sandwich it from both the top and bottom sides.
To eliminate uneven temperature differences depending on the location of the plate, copper plates with good thermal conductivity are placed on both sides or one side of the target metal plate, and an oxide film is applied to prevent seizure between the copper plate or graphite plate and the target metal plate. A thin heat-resistant steel sheet containing An or St is layered on both sides of the target metal, and the whole is heated uniformly to a high temperature higher than the recovery temperature of the target metal plate using a heat insulating material. A method for straightening the flatness of metal plates such as stainless steel, which is characterized by cooling after removing distortion.

2. A graphite plate is placed horizontally as a surface plate, and in order to eliminate uneven temperature differences depending on the location of the plate, a copper plate with good thermal conductivity is placed on top or below this graphite plate, and on top of these, In order to prevent seizure between the copper plate or graphite plate and the target metal plate, place the target metal plate whose flatness is to be corrected between thin heat-resistant steel plates containing Al or Si on which a thin oxide film has been formed, and place the target metal plate to correct its flatness. After further placing small piece weights on the entire surface, the whole is heated uniformly to a high temperature above the recovery temperature of the target metal plate using a heat insulating material, and after removing distortion in a flat state, it is cooled. A method for straightening the flatness of metal plates such as stainless steel.

Hereinafter, the present invention will be explained with reference to the drawings.

One of the features of the present invention is that, in order to obtain flatness during high-temperature distortion removal, a graphite plate that does not produce distortion at high temperatures is used as a surface plate, and a method is adopted in which the entire target metal plate is pressed from above and below. be. That is, a graphite plate (3) with good flatness is used as the lower substrate, and the target plate whose flatness is to be corrected is placed on the upper and lower sides.
It can be sandwiched between two graphite plates (3) (Fig. 1), or it can be sandwiched between a lower graphite plate (3) and a large number of small flat pieces placed on the upper side (6).
The flatness is obtained by sandwiching the wafer and the wafer (Fig. 2).

A small block of heat-resistant steel or a heat-resistant brick is suitable as the small piece weight. By arranging many small pieces of weight over the entire surface, the load is applied uniformly to the target metal plate.

One of the other features of the present invention is that in order to eliminate unevenness in the temperature difference between the 5 objective metal plates, copper plates (4) with good thermal conductivity are placed on both the upper and lower sides of the objective metal plate (Fig. 1), or on one side. (Figure 2). By using a copper plate (4) having a larger area than the target metal plate (1), non-uniformity in temperature difference can be further reduced. The position of the copper plate (4) may be either between the graphite plate (3) and the target metal plate (1) or outside the graphite plate (3).

FIG. 4 shows an example of how distortion occurs when heating is performed without using a copper plate as shown in FIG. In other words, if a copper plate is not used, the temperature distribution of the plate wall during heating and cooling will be uneven, so the plate will not be flat after cooling, and the circumference of the 500 mm square plate will stretch and rise as much as 3 mm on the surface plate. occurred. For example, when 5US304 is heated, there is a temperature difference of 10°C between the center of the board width and the periphery, and if the flattened product in this state is cooled to room temperature and the temperature becomes the same, the temperature difference between the periphery and the center is 0.016%. A difference in length (calculated assuming that the coefficient of thermal expansion of SUS304 is 16xlO-6) occurs.

As an approximate solution, if we use Vitagoras' theorem to calculate the height y of the uplift on a board with a side of 500 mm as shown in Figure 5, we get: The height y of the uplift is approximately 4 mm. Therefore, in the case of Fig. 4, it is thought that there was a temperature difference of about 10°C between the periphery and the center.

In the present invention, by using a copper plate, it is possible to reduce the temperature difference in the width direction during heat retention and cooling of the target metal plate, but it is more preferable to use a copper plate as shown in FIGS. PurposeWhen metal plate (1), heat-resistant plate (2), copper plate (4), etc. are wrapped with heat insulating material (5) so that heat flows only in the thickness direction, distortion can be prevented from occurring, which is good. results.

Furthermore, one of the other features of the present invention is that A1 has a thin oxide film formed on its surface in order to prevent seizure between the copper plate (4) or the graphite plate (3) and the target metal plate (1). Alternatively, the target metal plate (1) is sandwiched between upper and lower heat-resistant steel thin plates (2) containing Si.

For example, when a 5US304 stainless steel plate (1) was sandwiched between upper and lower graphite plates (3) and heated in a vacuum,
The phenomenon of burning of 5US304 onto the graphite plate was observed,
8 to heat-resistant steel (18Cr-3,5Aj2) containing A1
When a temper color was prepared by heating in the air at 00° C. for 3 minutes and this was sandwiched between a graphite plate and 5US304 (Fig. 3), the seizure phenomenon could be eliminated. If you use a heat-resistant steel plate that contains 2% or more of A1 or Si by weight and generate an oxide film of aluminum oxide or silicon oxide that is difficult to peel off on the surface of the plate in advance, these will not react with the copper plate or graphite plate. This has the advantage of preventing burn-in. Heat-resistant steels include heat-resistant steels containing 2% or more of AJZ or Si, such as Fe-15 to 30% Cr-8 to 25%
Ni-2~3%Si and Fe-15~30%Cr-2~3
%Si or Fe-10~30%Cr-2~6%An or F
e-15~30%Cr-20~40%Ni-2~6%A
fi etc. is optimal. Further, the thickness of the heat-resistant steel plate is preferably 1 mm or less.

The heating method may be heating in the air, but since the target metal plate is oxidized and an additional descaling step is required, it is preferable to heat in vacuum or in an inert gas atmosphere. Further, the metal plate is not limited to stainless steel, and the method can also be applied to iron-based brass, nickel-based alloys, and the like.

The present invention has achieved remarkable results in correcting the flatness of metal plates by combining the above-mentioned three features. Next, the present invention will be specifically explained using examples.

(Example 1) Flatness correction of a thin plate of 5US304 sandwiching graphite from both sides As shown in Fig. 1, a thin plate (1) of 5US304 with a thickness of 1.5 mm and a square of 500 mm was heated to generate a temper color at 800°C. 18Cr-3,5A! Heat-resistant steel plate (2) (
2) from both sides, and a 10mm thick copper plate (
4) Place 15mm thick graphite plates (3) (3) on the outside of (4), and insulate the gaps between these plates (5).
Filled with. These sets were heated to 1000° C. for 30 minutes in a vacuum and then slowly cooled. After taking out from the vacuum furnace, 5U
When the S304 thin plate was placed on the surface plate, it came into close contact with the surface plate.

(Example 2) The number of 5US304 plates (1) in Example 1 was increased to three, four 18Cr-3,5Au heat-resistant steel plates (2) were set on both sides of each plate, and the same experiment as in Example 1 was conducted. When tested, all 5US304 plates were in close contact with the surface plate.

(Example 3) 5US6 produced in a factory on an annealing and pickling line at 1100°C
A 1.5 mm thick thin plate (1) of No. 31 was cut into 500 mm square pieces, and as shown in Fig. 1, a 18Cr-3,5 Au heat-resistant steel plate (2
) (2) from both sides and apply 10mmJ to the outside! X-sized copper plate (4) (4) and 15mmJ on the outside!
J-size graphite plates (3) (3) were placed, and the set was heated to 950°C in a vacuum for 30 minutes, cooled in a vacuum cooling chamber for 20 hours, taken out, and placed in a pool of liquid nitrogen in this state. It was soaked and left in the cooled state for 8 hours.

After charging this into the vacuum furnace again and keeping it at 510℃ for 60 minutes,
Air cooled. When the 5US631 plate subjected to the precipitation hardening treatment was placed on the surface plate, it came into close contact with the surface plate. Also, the hardness is H
v398 and was sufficiently cured.

(Example 4) As another application example of this method, an attempt was made to correct the flatness of a plate that had jumped up due to welding stress. 0.5mm thickness x 300mm
Two sheets of 5US304 with a diameter of 500 mm were stacked together and the periphery was seam welded. When this plate was placed on a surface plate, the entire circumference bounced 10 to 20 mm. Therefore, as shown in Figure 2, a copper plate (4) is placed on a graphite surface plate (3),
18Cr-3,5AI with temper color on it
Place the L heat-resistant steel plate (2) and place the seam welding plate (1) to be straightened.
), and on top of that another 18Cr-3,5AJ2 heat-resistant steel plate (2) with a temper color attached, and on top of that, a heat-resistant steel plate (6) with a thickness of 15 mm x 50 mm x 50 mm was placed as a weight in 10 rows x Arranged in 6 rows. Also, as shown in the figure, a heat insulating material (5) was placed around the area. 1 set of these
The sample was placed in a vacuum furnace at 000°C, heated, kept for 30 minutes, and slowly cooled. When the seam welded plate (1) was taken out and placed on a surface plate, it became almost flat, although there were some areas around it with gaps of 0.1 mm or less.

(Effects of the Invention) According to the present invention, remarkable effects can be obtained in flatness correction of metal plates such as stainless steel plates, as shown in the examples.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a set for carrying out the method of the present invention. FIG. 2 is a schematic diagram showing another example of a set. 3 to 5 are figures other than the present invention, and FIG. 3 is an explanatory diagram of anti-seizing. FIG. 4 is an explanatory diagram showing an example of a state in which distortion occurs. FIG. 5 is an explanatory diagram of an example of approximate calculation of the uplift height when distortion occurs. 1. Purpose metal plate 4. Copper plate 2, heat-resistant steel thin plate 5. Insulation material 3, graphite plate 6. 'f- of the small piece weight drawing
Book (no change in content),! j'1 Figure 2

Claims (1)

[Claims] 1. Two graphite plates are used as a surface plate, and the metal plate whose flatness is to be corrected is placed horizontally so as to sandwich it from both upper and lower sides,
To eliminate uneven temperature differences depending on the location of the plate, steel plates with good thermal conductivity are placed on both sides or one side of the target metal plate, and an oxide film is applied to prevent seizure between the copper plate or graphite plate and the target metal plate. A thin heat-resistant steel sheet containing Al or Si is stacked on both sides of the target metal, and the whole is heated uniformly to a high temperature above the recovery temperature of the target metal plate using a heat insulator, and then the sheet is heated in a flat state. A method for straightening the flatness of metal plates such as stainless steel, which is characterized by cooling after removing distortion. 2. A graphite plate is placed horizontally as a surface plate, and in order to eliminate uneven temperature differences depending on the location of the plate, a copper plate with good thermal conductivity is placed on top or below this graphite plate, and on top of these, In order to prevent seizure between the copper plate or graphite plate and the target metal plate, the target metal plate whose flatness is to be corrected is placed between thin heat-resistant steel plates containing Al or Si on which a thin oxide film is formed. After further placing small piece weights on the entire surface, the whole is heated uniformly to a high temperature above the recovery temperature of the target metal plate using a heat insulating material, and after removing distortion in a flat state, it is cooled. A method for straightening the flatness of metal plates such as stainless steel. 3. The method according to claim 1 or 2, wherein the target metal plate is precipitation hardening stainless steel after solution heat treatment.