JPH0635014B2 - Metal foil shape correction method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for correcting the shape of a metal foil, and more particularly to a method capable of effectively preventing oxidation of the rolled metal foil when correcting the flatness of the rolled metal foil. Is.

(Background Art) Recently, a foil material made of tungsten, molybdenum, an alloy thereof, or the like having a thickness of about 50 μm or less has been used for electronic device parts and the like. Since these materials are generally extremely hard, the flatness of the target foil material after being rolled is corrected, that is, the undulation in the plate thickness direction of both side edges of the strip-shaped foil material (ear wave). ), It can hardly be corrected by using a roller leveler or a tension leveler for normal plate material correction. Method has been adopted.

By the way, as a method of such tension annealing, for example, the foil material sent from the rewinding roll is allowed to pass through the bridle roll group on the entry side, and then continuously run in a long heating furnace, and then the exit side. It is known that a rewind roll is wound up through a group of bridal rolls, in which a foil material is subjected to a frictional force between the wound bridging rolls on the input side and the bridging roll on the output side. It will be possible to proceed at the same speed as the peripheral speed of the bridal roll, but at that time, by setting the peripheral speed of the exit side bridal roll to be slightly higher than the peripheral speed of the entrance side bridal roll, Corresponding elongation deformation is given to the foil material, that is, the foil material is subjected to elongation deformation in the heated state in the furnace, and its flatness is corrected. It has become as to be.

Further, the applicant of the present invention has previously proposed, as Japanese Patent Application No. 61-62566, to a predetermined metal foil material in order to solve the problem of the reduction of the correction yield of the foil material in the tension annealing using the bridal roll. Then, a new method was proposed in which hot tensile deformation was sequentially applied in the longitudinal direction so that the straightening operation was finally performed over the entire length. That is, after the foil material is chucked at both ends in the longitudinal direction, a tensile force is applied to the foil material, while the furnace length is shorter than between the chucking portions, and a part of the foil material is surrounded and heated. The heating furnace is moved in the longitudinal direction along the foil material to sequentially apply hot tensile deformation to the foil material.

However, in these shape correction methods by tension annealing, the metal foil material is likely to be heated in an oxidizing atmosphere such as the atmosphere or is exposed to such a state, and therefore the foil material is oxidized. Therefore, there is a problem that the quality or the characteristic is deteriorated. In any of these methods, the heating furnace cannot be made completely closed, so that the atmosphere inside the furnace becomes an oxidation incomplete atmosphere, and therefore the foil is not exposed in such an atmosphere. This is because the material will be heated. For example, the furnace type is generally a half type, and particularly in the tension annealing method proposed by the applicant of the present application, the furnace length is extremely short (500 to 1000 m).
m) etc., the sealing at the opening will be incomplete, so it is extremely difficult to prevent the oxidation of the foil material even if a reducing or inert atmosphere gas is flown into the furnace. It becomes.

However, as one method of preventing the oxidation of the foil material, there is a method of applying an antioxidant to the surface of the foil material in advance, as the antioxidant, commercially available products or water glass, or such water glass It has been clarified that Al ₂ O ₃ powder and the like are mixed and applied, but such a method has an incomplete antioxidation function itself or has poor compatibility with the foil surface. There is a problem that uneven coating may occur and local oxidation may occur, and in order to remove the antioxidant after tension annealing, a strong acid, for example, in the case of water glass, 37.5% concentrated nitric acid (HNO ₃ ) And 37.5% concentrated hydrogen fluoride (HF) mixed acid solution and the like, there is an inherent problem that treatment with a highly dangerous solution is required.

(Structure of the Invention) Here, the present invention has been made in view of such circumstances, and an object thereof is to provide an antioxidant method which addresses the above problems, More specifically, it is a method of applying an antioxidant, which has a uniform coating property, substantially prevents oxidation, and can easily remove the antioxidant after tension annealing (shape correction). Is to provide.

Then, in order to achieve such an object, in the present invention, by subjecting the metal foil to be corrected to heat treatment by applying a predetermined tensile force under the condition of being exposed to an oxidizing atmosphere. For shape correction, (a) a step of applying a 55 to 70% aqueous solution of water glass on the surface of the metal foil, and (b) a metal foil coated with the aqueous solution of water glass at room temperature for 3 to 8 hours. , A drying process,
(C) Immediately after the drying treatment, a step of applying the shape correcting operation, and (d) a step of boiling the shape-corrected metal foil in boiling water to remove water glass on the surface of the metal foil. It is characterized in that it is configured to include and.

As described above, in the present invention, water glass is used as an antioxidant, and it is used as a solution with water to ensure uniform applicability on the foil surface by optimizing the concentration, and after application. By optimizing the drying operation, it is possible to remove the water glass after tension annealing only by boiling with hot water, thereby achieving effective oxidation prevention of the foil material to be tension annealed, It was possible to easily and easily prevent the water glass (antioxidant) used from using, without using a strong acid solution having a great risk.

The shape correction operation to which the present invention is advantageously applied is such that both ends of the metal foil are chucked, and a predetermined tensile force is applied, while the length is shorter than the length between the chucking portions. By using a heating furnace capable of surrounding and heating a part of the metal foil, the metal foil is sequentially heat-treated in its chucking direction by its relative movement with respect to the metal foil to heat the metal foil. It is carried out by imparting a tensile tensile deformation.

(Specific Description of Configuration) By the way, as the metal foil to which the shape correcting method according to the present invention is applied, all metal foil materials that are exposed to an oxidizing atmosphere and oxidized during shape correction by tension annealing are targeted. However, in this case, it is particularly hard to use a material other than tension anneal, such as a tension leveler, whose shape cannot be corrected. Those that cannot form a standard foil are mainly targeted, for example, Tungten foil, molybdenum foil, tungsten-molybdenum alloy foil, and the like. It should be noted that such a metal foil is generally used as a short foil material having a length of about 10 to 20 m.

Then, such a short metal foil is advantageously shape-corrected according to a correction method as shown in FIG. That is, in FIG. 1, the short metal foil 2 is
One end of the straightening machine bed 4 is fixed at one end by tightening through the chuck 6, while the other end is fixed at the slide head 10 by tightening through the chucking 8. Can be set. Then, the slide head 10 is pulled in the direction of the arrow A by a pulling means (not shown) such as hydraulic pressure so that a predetermined pulling force is applied to the metal foil 2. On the other hand, the half-divided heating furnace 12 in a vertically divided form is set on the slide rail surface 18 of the bed 4 via the furnace bases 14 and 16 and is movable in the left-right direction in the drawing. In addition, this half furnace 12
The rail surface 20 of the furnace base 16 enables the slide in the direction perpendicular to the paper surface.

Therefore, in the apparatus having such a structure, first, the heating furnace 12 is heated to a predetermined temperature at a position retracted from the position of the foil material 2 in a direction perpendicular to the paper surface, and then the half-opening is performed. Then, the metal foil 2 is slid on the slide rail surface 20 to a position where it is wrapped in the furnace, then the half furnace 12 is closed, and then the furnace 12 is slid on the slide rail surface 18, as shown in the drawing. By moving the metal foil 2 in the left-right direction, the shape of the metal foil 2 is straightened over its entire length while being partially heated in the lengthwise direction. That is, in this way, it is possible to sequentially apply partial heating to the metal foil 2 to which a constant tension is applied over the entire length, and to give a heating history to the entire length, and This heating and pulling operation (tension annealing) corrects the shape of the metal foil.

By the way, according to the present invention, a 55-70% aqueous solution of water glass is previously applied to the surface of the metal foil 2 which is subjected to the shape correction by the tension annealing method. In addition, the water glass concentration in this water glass aqueous solution must be optimized in order to ensure uniform coating property on the surface of the metal foil 2. In the present invention, the concentration is 55 to 70% (weight basis). ) Will be limited to. If the water glass concentration is less than 55%, the compatibility with the surface of the metal foil becomes poor, and a portion that is not sufficiently covered with water glass remains, causing a problem of oxidation of the portion. When the concentration exceeds, the coating thickness with water glass tends to be excessive, and when heated rapidly, foaming is remarkable, which causes problems such as a large number of minute areas being oxidized. is there.

In applying the aqueous solution of water glass having such a concentration to the metal foil 2, various known coating methods can be appropriately adopted, and examples thereof include a dipping method and a brush coating method.
A method such as a spray method will be appropriately selected.

In addition, the metal foil 2 thus coated with water glass in an aqueous solution having a predetermined concentration is subjected to a drying operation for 3 to 8 hours at room temperature. Also, optimization of this drying condition is an important technical matter in the present invention, and removal of water glass after tension annealing can be performed only by a simple removal operation by boiling. The conditions for drying at room temperature without drying are adopted, and the drying time must be 8 hours or less. In addition, if the drying time is less than 3 hours, the drying becomes insufficient, which causes inconvenience such as outflow during handling, and the formed water glass film is peeled off due to contact with other objects to cause local oxidation. Therefore, the drying time needs to be at least 3 hours or more, because it causes problems such as that.

The thus-dried metal foil 2 is immediately heat-treated by a device as shown in FIG. 1 under a predetermined tensile force.
A predetermined shape correction operation is performed by tension annealing. However, the shape correction operation to which the method of the present invention is applied is by no means limited to the method shown in FIG. 1 and may be applied to other shape correction methods by tension annealing. Needless to say. Further, in the apparatus having the structure as shown in FIG. 1, it is possible to fix the heating furnace (12) and move the bed (4) side.

Further, the metal foil 2 subjected to such a shape correction operation is removed from the apparatus and then subjected to boiling treatment in boiling water to remove water glass present on the surface of the metal foil 2. Will be done. In particular, in the present invention,
As described above, the concentration of the aqueous solution of water glass to be applied is optimized, and since the drying treatment conditions of the applied metal foil are also optimized, without using a dangerous strong acid solution, simply The water glass on the surface of the metal foil 2 can be effectively removed only by the boiling treatment.

(Examples) Examples of the present invention will be shown below to clarify the present invention more specifically, but the present invention is not limited by the description of the examples. Needless to say.

In addition to the following embodiments, the present invention includes various changes and modifications based on the knowledge of those skilled in the art without departing from the spirit of the present invention, in addition to the above specific description.
It should be understood that improvements and the like can be added.

First, as a metal foil to be straightened, a sample of pure tungsten having a plate thickness of 25 μm, a plate width of 70 mm and a length of 3 m was used. Further, as the antioxidant, a commercially available antioxidant for steel materials (turbid solution in water: commercial product A) and various water glass aqueous solutions having a concentration of 40% to 100% were used.

Then, the pure tungsten foil material was dipped in each antioxidant aqueous solution, then pulled up and dried in the atmosphere at room temperature for various drying times of 1 to 24 hours.

Next, each of the dried various kinds of the antioxidant coated foils was set in the apparatus shown in FIG. 1 and subjected to a tension annealing treatment at a tension of 90 kgf / mm ² and a temperature of 800 ° C., respectively. After that, it is immersed in boiling water at 100 ° C. and boiled for 5 minutes to remove the antioxidant adhering to the surface of the straightened foil material, and then dried and dried on the foil surface. The area ratio (per 1 m of foil length) of the remaining surface-oxidized portion and the presence or absence of the remaining glass particles were visually measured with a loupe (× 20).

Then, based on the measurement, the result of the drying time of 5 hours is shown in FIG. 2 as the area ratio of the oxidized portion remaining in black brown on the foil surface after the tension annealing. In addition, when the commercially available antioxidant A was applied, it was found that oxidation was caused over the entire surface of the foil material, and it was found that there was no effect. Further, it was confirmed that when the concentration of the aqueous solution of water glass was less than 55%, the compatibility with the foil surface was poor, and a portion that was not sufficiently covered remained and that portion was oxidized. On the other hand, when the concentration of water glass exceeds 70%, the coating thickness tends to be excessive, and rapid heating causes remarkable foaming, which causes a large number of minute area oxidations. Therefore, the concentration of water glass that can completely prevent oxidation is 55 to 70%.
Was found to be appropriate.

Further, FIG. 3 shows the results of an examination of the presence or absence of water glass particles remaining on the foil surface of a foil material coated with 60% and 70% aqueous solutions of water glass. In FIG. 3, “existence” means that the glass particles can be seen visually by shining, and “extreme amount” means that the glass particles can be seen by shining with x20 loupe.

As is clear from the results of FIG. 3, when the drying time is 8 hours or less, even if water glass remains, there is a very small amount, and there is almost no problem in using as a foil, but even if it is 10 hours or more In that case, the residual amount increases, and it is recognized that some kind of support is required for use.

(Effects of the Invention) As is apparent from the above description, according to the present invention, when correcting the shape of a metal foil material exposed to an oxidizing atmosphere, a uniform water glass (antioxidant) is formed on the surface of the metal foil. The film is formed to achieve complete oxidation prevention of the metal foil during heating, and after heating, the water glass can be removed by simple boiling. It can be advantageously carried out without causing any problem of oxidation of the metal foil.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view showing an example of a shape correcting device used in the present invention, and FIGS. 2 and 3 respectively show
3 is a graph showing the relationship between the water glass concentration and the oxidized partial area obtained in Examples, and a graph showing the relationship between the drying time and the residual amount of water glass. 2: Metal foil, 4: Straightener bed 6, 8: Chuck, 10: Slide head 12: Heating furnace, 14, 16: Furnace stand 18, 20: Slide rail surface

Claims (2)

[Claims] 1. When the metal foil to be straightened is subjected to a heat treatment by being subjected to a predetermined tensile force under the condition of being exposed to an oxidizing atmosphere, the shape of the metal foil is corrected. A step of applying a 55-70% aqueous solution of water glass, b) a step of drying the metal foil coated with the aqueous solution of water glass at room temperature for 3 to 8 hours, and c) after the drying treatment. Immediately, a step of applying the shape correcting operation, and d) a step of boiling the shape-corrected metal foil in boiling water to remove water glass on the surface of the metal foil are configured. A method for correcting the shape of a metal foil, characterized by: 2. The shape correcting operation chucks both ends of the metal foil to exert a predetermined tensile force on the metal foil, and a part of the metal foil in a length shorter than a length between the chucking portions. A heating furnace capable of surrounding and heating the metal foil is used to sequentially heat the metal foil in its chucking direction by its relative movement with respect to the metal foil to impart hot tensile deformation to the metal foil. The method for correcting the shape of a metal foil according to claim 1, wherein the method is carried out.