JPH0673514A - Annealing method of metal foil and winding core used therefor - Google Patents

Abstract

PURPOSE:To reduce the dispersion of temps. between coils and in the coils and to efficiently anneal a metal foil at the optional temp. by winding the metal foil in coiled state heating with heat conduction from a winding core side of this coil. CONSTITUTION:At the time of annealing the metal foil wound in the coiled state, the heat treatment is executed by heating with the heat conduction from the winding core side of this coil. As this heating means, e.g. a method for embedding a sheath heater 1 into the winding core 2 and connecting with a power source 3 or a method for inserting an infrared tubular heater into the winding core and electrically inserting the winding core directly energizing, or further, a method for closely inserting a cylindrical cartridge heater in the winding core, etc., is provided. Further, a uniform heating in the heated annealing furnace by covering the outer surface or the side surface of the coil with a flat exothermic body or by an auxiliary means for executing in a heat insulating chamber, etc., is preferable for this heating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an annealing method for degreasing and annealing a rolled metal foil, and more particularly to an annealing method effective in vacuum annealing and a coil core suitable for use in the annealing method.

[0002]

2. Description of the Related Art Metal foil has metallic luster and conductivity,
It has excellent barrier properties against gas and moisture, light shielding properties, and is widely used in decorative materials, conductive materials, packaging materials, machine materials, etc., and soft, ductile metals such as aluminum, copper, gold, and silver are used as metal foils. Widely used. In particular, since aluminum is used in large quantities as the main component of metal foil, the following aluminum foil (aluminum in the present invention means both aluminum and aluminum alloy, and foil is thinner than about 2 mm even if it is 200 μm or more) If the material is a plate-shaped material, this is included.) Will be described as a representative, but the same can be applied to other metals.

Annealing of an aluminum foil is generally carried out by winding a rolled aluminum foil into a coil, placing the coil (aluminum foil wound into a coil) in a heating furnace (annealing furnace), and heating the entire furnace. Annealing and rolling oil are removed.

The heat transfer from the heating furnace to the coil at this time is due to convection and radiation from the heating means.
In particular, when performing vacuum annealing, there is no gas convection, so there is no choice but to rely only on radiation, and many problems arise.

For example, (1) In the case of heat-treating a plurality of coils at one time, if the positional relationship of each coil is not proper, a shadow portion will be generated from the heating means, and between the coils and within one coil. The temperature tends to be uneven. (2) Of the amount of heat supplied for heat treatment, the amount of heat supplied to the coil by heat transfer due to radiation is a small part of it, and most of it is spent for raising the temperature and radiating heat of the furnace itself, resulting in low thermal efficiency. . (3) It is difficult to control the temperature of the coil because the time lag from the start of the heating of the heating furnace to the start of the heating of the coil is large. (4) When the coil is heated only by radiation or by convection and radiation, it is gradually heated from the outside of the coil, so that the outside of the aluminum foil expands due to thermal expansion and the coil winding loosens. The heat transfer due to the contact between the layers increases the heat transfer resistance due to the formation of a minute gap between the foil layers, and the temperature becomes nonuniform between the inner and outer layers of the coil. There was such a problem.

As a result, the removal of rolling oil becomes insufficient,
Since it causes troubles in subsequent printing and lamination, it is unavoidable to remove the rolling oil by carrying out a heat treatment for a long time as a countermeasure, and this heat treatment process has become a bottleneck in the aluminum foil manufacturing process. .

[0007]

DISCLOSURE OF THE INVENTION According to the present invention, in the step of heat-treating a metal foil wound in a coil shape, (1) variations in temperature between each coil and within each coil are eliminated, and the treatment temperature of each coil is Control arbitrarily. (2) Energy efficiency is improved, especially in vacuum annealing. The purpose of the invention is to develop a method of annealing a metal foil that can be used, and a means that enables it.

[0008]

DISCLOSURE OF THE INVENTION The present invention is a method for annealing a metal foil and a method for annealing a metal foil, characterized in that, in heat treatment of a metal foil wound in a coil shape, the core side of the coil is heated by heat conduction. The above object was achieved by developing a core for a metal foil coil, which is characterized in that a heating means is incorporated in the core when the core is wound and heat-treated.

In the present invention, examples of the metal foil include soft and malleable metals such as aluminum and copper, precious metals such as gold and silver, and metals such as iron. Among them, the soft and malleable metals such as aluminum and copper are preferable. Rolled foil (about 2
A metal plate material thinner than mm is suitable.

In the so-called batch annealing in which the metal foil, for example, an aluminum foil is heat-treated while being wound in a coil on a winding core, in the present invention, a heating means is provided on the winding core around which the aluminum foil is wound to heat the batch annealing. The core is heated and this heat is heated as uniformly as possible by the heat conduction of the aluminum foil.

The winding core may be an iron or aluminum pipe, and as the heating means, (1) a sheath heater is embedded in the pipe. (2) Insert the infrared tubular heater into the center of the winding core. (3) The surface of the core is insulated and the core is directly energized. (4) Insert the cartridge heater into the core so as to be in close contact with the inner surface of the pipe. The above method or a method of passing a heating medium (liquid or gas) through the core may be adopted as appropriate depending on the processing conditions of the target metal foil, the site conditions, and the like.

At this time, in order to make the temperature of the surface of the pipe uniform, the surface of the winding core is made of metal such as copper having good heat conductivity, or the amount of heat radiation is larger at both ends than the center of the coil, or in the width direction of the foil. When the winding force is different and the thermal resistance becomes non-uniform, it is also a good method to control the amount of heat generation by making the winding pitch of the heater sparse in the central part and making both ends dense.

Further, in order to reduce the heat radiation amount of the heat treatment, reduce the heat loss, and facilitate the control of the temperature of the entire coil, heat treatment is performed in a conventional annealing furnace or a heat insulating chamber as an auxiliary means of heating, or A planar heating element may be adhered to and heated on the outer and side surfaces of the coil. Even when external heating is not performed, it is necessary to shield the coil surface from the outside air with a heat-resistant woven fabric such as glass fiber or rock wool except in vacuum annealing.

The conditions such as heat treatment temperature and heat treatment time vary depending on the material of the metal foil to be treated, the required degree of annealing, the size of the coil, etc. and are not constant, but for aluminum foil, they are shorter than those for batch annealing. ˜450 ° C., several hours to several tens hours.

[0015]

The present invention is characterized in that, when the metal foil is heat-treated while being wound into a coil, the core itself is heated and the temperature of the core is heat-conducted from the inside of the coil to heat the entire coil.

It is not necessary to limit the heating means of the core itself, but in consideration of easiness of production and certainty of temperature control, it is preferable to use a sheath heater embedded in the core (see FIGS. 1 and 2). ).

The aluminum foil wound into a coil by a usual method expands thermally as the central winding core itself is heated, contrary to the case where it is heated from the outside, and the degree of adhesion with the outer aluminum foil is increased. The heat conductivity is greatly improved.
Furthermore, the aluminum foil of the inner layer expands and the degree of adhesion with the aluminum foil of the outer layer increases, so that the thermal conductivity can be maintained high.

This is because it is not necessary to consider the shadow of radiation in a vacuum heating furnace that relies only on radiant heating without convection of air in the heating furnace, and since it is heating by heat conduction, it has good thermal conductivity such as aluminum and copper. There is a merit that it is not necessary to consider the reflection of radiation in metals such as silver.

When the winding diameter of the coil is large or the temperature difference from the outside air temperature is large, external heating may be used together. Even in such a case, when the heating means of the core is used, even if the heat treatments are collectively performed, it is possible to heat-treat a plurality of coils without variations, and conversely, it is possible to control each coil independently under each condition. Is.

[0020]

EXAMPLE As shown in FIG. 1, a groove is provided in the circumferential direction on a winding core 2 of an aluminum pipe having an outer diameter of 80 mmφ, and a 3.2 mm sheath heater 1 is wound at a pitch of 20 mm. As shown in FIG. Embedded in. This core has a width of 500
mm, 100 μm thick aluminum foil wrapped 100 m thick
Put one coil wound to a thickness of m into the vacuum chamber,
Heating was not performed from the outside, and only the heater of the core was used for heating at a temperature rising rate of 50 ° C./hr and a heat treatment temperature of 400 ° C. × 2 hours.

Because of the heating by the heater closely attached to the foil,
The curtailment became smaller, and the target heating profile was used as it was for the heater heating program, but as shown in FIG. 3, the foil body could be heated almost as targeted. In addition, since the foil is heated from the inside of the foil, the foil inside becomes hot and stretches first, so the force that makes the winding more tight acts and the resistance to heat transfer to the outside becomes smaller, and the center of the foil is wound. The temperature difference between the outer circumference and the outer circumference was 15 ° C.

(Comparative Example) A coil of the same aluminum foil as that of Example 1 was prepared except that a simple aluminum pipe having a diameter of 80 mm and having no heating means was used as the winding core. The coil was placed in a vacuum chamber used in Example 1 which can be heated by an electric heater from the outside, and the coil was evacuated and electrically heated from the outside. In order to make the coil temperature have the target heating profile shown in FIG. 4, it was necessary to consider a time lag with the heater and to make a heater program such as the heater heating program of FIG. At this time, the temperature of the foil body was S-shaped with respect to the target profile, and the temperature was overheated by 50 ° C. from the target value.
Further, a maximum temperature difference of 30 ° C. (about twice as much as that of the method of the present invention) occurred between the center and the outer peripheral portion of the foil.

Since the foil is heated from the outside, the foil wound on the outside is first heated to a high temperature and is loosened due to thermal expansion, so that a minute gap is generated at the overlapping interface of the foils or the contact degree is high. It is considered that the heat resistance increases due to weakening.

[0024]

EFFECT OF THE INVENTION By providing a heating means on the core and annealing the metal foil by heating the metal foil by heat conduction from the center of the coil (core), (1) when simultaneously annealing a plurality of coils together, Since all the coils can be heated under the same conditions, it is possible to eliminate temperature variations among the individual coils, and to independently control the temperature rising conditions for the individual coils. (2) Since it is not necessary to heat the entire periphery such as in an annealing furnace, heat loss can be reduced and required energy can be reduced. (3) Since the heat transfer is excellent, the time lag of temperature rise is reduced, and the temperature control of the coil is easy. (4) Since the heating is performed from the winding core, the resistance of the heat conduction in the radial direction is reduced and the variation in the coil is reduced. (5) Especially in vacuum annealing in which heat conduction by convection is not possible, there is no need to consider radiation, so there is no problem with the positional relationship of the coils or shadows, and thermal efficiency can be kept high.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a winding core in which a sheath heater is embedded.

FIG. 2 is an enlarged cross-sectional view of an embedded portion of a sheath heater.

FIG. 3 is a temperature rising curve of vacuum annealing according to the method of the present invention.

FIG. 4 is a temperature rising curve of vacuum annealing according to a conventional method.

[Explanation of symbols]

 1 Sheath heater 2 Core 3 Power supply 4 Silver low

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuo Otsuka 6-224 Kaiyamacho, Sakai City, Osaka Prefecture Showa Aluminum Co., Ltd.

Claims (5)

[Claims] 1. A method for annealing a metal foil, which comprises heating the coil-shaped metal foil by heat conduction from the winding core side of the coil. 2. The heating means includes (1) heating means in which a heater is embedded in a winding core, (2) heating means in which an infrared tubular heater is inserted in the winding core, and (3) heating in which electricity is directly applied to an electrically insulated winding core. Means (4) The method for annealing a metal foil according to claim 1, wherein any one of (4) a heating means in which a cylindrical cartridge heater is inserted into the winding core in a close contact state is used. 3. The heating step comprises: (1) heating in a heated annealing furnace; (2) heating from both sides of the coil while the outer surface and / or side surface of the coil are covered with a planar heating element (3) heat insulation The method for annealing a metal foil according to claim 1, wherein the heating is performed by placing a coil in a room and heating. 4. A winding core for a metal foil coil, wherein a heating means is built in the winding core when the metal foil is wound in a coil shape and heat-treated. 5. As heating means, (1) heating means in which a heater is embedded in a winding core (2) heating means in which an infrared tubular heater is inserted in the winding core (3) heating in which electricity is directly applied to an electrically insulated winding core Means (4) The core for a metal foil coil according to claim 4, wherein any one of heating means in which a cylindrical cartridge heater is inserted into the core in a close contact state is used.