JPH07267237A - Draw-ironed can made of steel - Google Patents

Abstract

PURPOSE:To prevent wrinkles at the time of neck processing, and cracking at the time of flange processing or seaming processing from occurrence, and improve the sealing property and corrosion resistance by specifying a mouth contraction percentage, plate thickness and micro-Vickers hardness of the starting part of a neck-in or its vicinity. CONSTITUTION:A draw-ironed can 1 has a side wall part 4 which is thinned by a stroke-processing, and a multi-stage neck-in processed part 5 on the top of the side wall part 4. Then, a flange 6 for seaming is connected to the top of the neck-in processed part 5, and a mouth part 7 with a smaller diameter is formed. This mouth contraction percentage is made 15% or higher, and a plate thickness at the neck-in start part P or its vicinity is specified in a range of 100-135mum. In addition, a micro-Vickers hardness Y at the neck-in start part P or its vicinity and a micro-Vickers hardness X at the inside of a bottom ground part Q are specified in a range which is specified by X+Y<=430 and Y<=240. By thinning the neck-in processed part 5, the can is made lighter, and the raw material cost is reduced. Also, a removing from a punch after stroking becomes easier, and the operatability is also improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel squeezing and ironing can, and more specifically, it has a tight sealing property, a corrosion resistance to a lid winding part and The present invention relates to a steel squeezed ironing can that has an excellent combination of flange crack resistance.

[0002]

2. Description of the Related Art A can body obtained by subjecting a metal material to a drawing-redrawing process between a punch and a die and an ironing process has a seam at a can body portion and a connecting portion between a can body portion and a can bottom portion. It has the advantages that it has a good appearance, does not require operations such as tightening the bottom lid and forming seams, and has a thinned can barrel side wall, which requires less metal material. From
Widely used for canned beverages.

Since such a two-piece can is used for contents such as beer and carbonated beverages having an autogenous pressure, nitrogen-filled cans, heat-sterilized cans and the like, pressure-resistant performance, impact resistance and resistance Corrosiveness is required. Aluminum is a material with excellent workability and has the advantage that it can be made extremely thin, but its strength is one-third that of steel, and it is suitable for foods containing corrosive components. Since steel has poorer corrosion resistance than steel, steel cans are still used for applications requiring heat sterilization and for contents containing corrosive components.

In a two-piece can, it is necessary to wind and fasten the flange portion on the upper portion of the can body with the easy open lid. However, the diameter of the expensive easy open lid is reduced to reduce the cost and the outer circumference of the winding portion. Neck-in processing is performed on the upper part of the can body to reduce the diameter of the mouth to a smaller diameter for the purpose of improving the appearance of the can body by making it inside the outer circumference of the can body. Recently, this neck-in processing is also required to be more sophisticated, that is, to be reduced to a smaller diameter by multi-step processing.

[0005]

However, in the squeezed and ironed can made of steel, reducing the thickness of the can body part including the neck-in processed part reduces the weight and cost of the can. Although desirable, it has been found that such a thinned and squeezed ironing can often results in poor sealing of the wound portion and reduced corrosion resistance.

As a result of investigating this cause, the inventors of the present invention have found that the above-mentioned poor sealing property and reduced corrosion resistance are caused by the generation of wrinkles in the neck portion and the flange portion during neck-in processing. It was found that cracks (flange cracks) occur during the flange processing and the winding tightening processing. The occurrence of wrinkles tends to become more prominent as the thickness at the neck-in start portion or in the vicinity thereof becomes smaller, and becomes more prominent as the aperture reduction ratio during neck-in processing increases.

Therefore, it is an object of the present invention to produce wrinkles during neck-in processing, flanging, and the like, while the neck-in processing portion has a thin wall and the tightening opening portion is neck-in processed to have a small diameter. It is an object of the present invention to provide a drawn and ironed can made of steel, in which flange cracks (flange cracks) at the time of winding processing are prevented and, as a result, excellent sealing performance and corrosion resistance of the lid winding portion are combined.

[0008]

According to the present invention, in a steel drawn and ironed can, which is formed by drawing and ironing a steel plate, and necking the winding mouth into a small diameter,
The aperture ratio is 15% or more, the thickness of the neck-in start portion or its vicinity is in the range of 100 to 135 μm, and the micro Vickers hardness (Y) and the bottom ground contact portion inside the neck-in start portion or its vicinity are The micro Vickers hardness (X) is defined by the formula: X + Y ≤430 (1), preferably X + Y ≤410 (1A), and Y ≤240 (2), preferably Y≤230 (2A). Provided is a steel squeezed ironing can which is excellent in sealing property, corrosion resistance in a lid-wound portion, and flange crack resistance, which is within the range.

[0009]

Each measurement according to the present invention is performed by the following method. 1) Method for measuring the micro Vickers hardness (Y) at the neck-in start portion The micro Vickers hardness (Y) at the neck-in start portion is
Regarding the neck-in start part, cross-section micro Vickers hardness (load 50g, 30
Second) and measure the average value. 2) Measuring method of micro-Vickers hardness (X) inside the bottom ground contacting part The micro Vickers hardness (X) inside the bottom grounding contact is measured every 45 ° in the can circumferential direction for the arc-shaped part on the dome side inside the bottom grounding contact. The cross-section micro Vickers hardness (load 50 g, 30 seconds) was measured at 8 points, and the average value is shown. 3) Neck-in start part plate thickness measurement method The neck-in start part plate thickness was measured by measuring the wall thickness of only the metal at 10 points in the can circumferential direction after peeling off the resin coating on the inner and outer surfaces of the neck-in start part. The average value is shown. 4) Measurement of aperture ratio The aperture ratio (%) is defined by the following equation (3). Squeeze rate (%) = ((can barrel inner diameter-rolling part inner diameter) x 100) / can barrel inner diameter ... (3)

The present invention relates to a steel drawn and ironed can which is formed by drawing and ironing a steel plate and necking-in the winding mouth portion to a small diameter. The thickness was reduced to 100 to 135 μm, which was not recognized in the past, and the aperture ratio was increased to 15% or more.

It has been well known that the body of a drawn and ironed can is thinned to the above-mentioned thickness by ironing, but in the portion where neck-in processing or flanging is performed, there is no wrinkle or crack-free flange. In order to form the portion, the degree of ironing of the above portion was purposely lowered, and the thickness thereof was generally set to about 140 μm.

On the other hand, in the present invention, a high ironing process is also applied to the neck-in process and the flange process, and this part is also thinned to reduce the weight of the can and reduce the material cost of the can. Is also aimed at reducing.

The plate thickness is limited to 100 to 135 μm because the plate thickness at the neck-in start portion and its vicinity is 100.
If it is less than μm, even if the requirements for the hardness of the can body described below satisfy the relationship of the present invention, if the necking ratio is 15% or more, the neck part and the flange part are formed in the necking and flanging molding. Defects such as wrinkles and micro cracks occur, and the sealing property, the corrosion resistance of the lid-wound portion, and the flange crack resistance deteriorate.

On the other hand, when the plate thickness at the neck-in start portion or in the vicinity thereof exceeds 135 μm, there are generally few defects during necking molding and flange molding with a draw ratio of 15% or more,
The sealability, corrosion resistance of the lid wrapping area, and flange crack resistance are good, but there is a step difference due to the large difference in plate thickness between the neck-in processing part and the body of the can, causing the can to fall out of the punch during ironing. Sex (strip-out property) deteriorates,
If the plate thickness of the neck-in processing part is large, the forming load during necking is large, so the can body is likely to buckle, the thickness of the can body cannot be reduced, and the metal usage of the can body increases, so it is economical. It has disadvantages such as being disadvantageous, the cost of transportation is high due to the weight of the can, and the feeling is disadvantageous because it feels heavy when drinking.

The mouth draw ratio is specified to be 15% or more. The reason is that the easy-open lid wound around the can body is reduced in diameter to reduce the cost of the lid, and the appearance characteristics of the whole canned food, especially the stability, etc. Is to improve.

In the present invention, in order to achieve the thinning of the neck-in processed portion and the improvement of the aperture reduction ratio, the micro Vickers hardness (Y) in the neck-in starting portion or in the vicinity thereof and the micro-Vickers inside the bottom grounding portion. It is a remarkable feature that the Vickers hardness (X) is within the range defined by the formulas X + Y ≦ 430, especially X + Y ≦ 410, and Y ≦ 240, especially Y ≦ 230.

Please refer to FIG. FIG. 1 shows the micro-Vickers hardness (X) inside the bottom ground contact portion as the horizontal axis and the micro-Vickers hardness (Y) at or near the neck-in start portion as the vertical axis. Evaluation of corrosion resistance and flange crack resistance is excellent (○),
The plots are good (Δ) and bad (×).

According to the result of FIG. 1, the straight line X + Y = 4
In the region above 30 and Y = 240, poor sealing,
In contrast to the corrosion of the lid-wound portion and the flange crack, these defects are effectively eliminated in the region below these straight lines, and in particular, the straight lines X + Y = 410 and Y = 230.
In the following areas, it is clear that a steel drawn and ironed can having a particularly excellent combination of sealing property, corrosion resistance of the lid-wound portion and flange crack resistance can be obtained.

If the value of (X + Y) is larger than 430,
Necking tends to cause wrinkles in the neck and flange portions, and cracks (flange cracks) occur at the time of flange processing starting from the wrinkles, increasing the number of in-line reject cans and reducing productivity. Even if it does not crack during flange processing, if there is a large wrinkle on the flange part, the unevenness of the wrinkle part will be large,
When it comes into contact with the lid when filling the contents, the inner surface of the lid is locally rubbed, the coating film is broken and the metal is exposed, so it is corroded by the filled contents. Ions may deteriorate the flavor of the contents. Further, the wrinkled portion of the flange is apt to be a flange crack during double winding, which causes a decrease in sealing performance. In addition, the wrinkles occurring in the neck portion have a poor appearance, which leads to a reduction in the commercial value of the can.

It should be understood that the absolute value of the micro Vickers hardness (Y) at or near the neck-in start is also important. That is, the value of (X + Y) described above is 4
Even if it is 30 or less, the neck formability is poor, and there is a range in which the sealability, the corrosion resistance of the lid-wound portion, and the flange crack resistance are inferior due to the wrinkles and cracks of the flange portion and the neck portion. The reason for this is not clear, but even if the hardness of the neck-in processed part is the same, due to the method of work hardening (depending on the type of steel base material) when drawing and ironing the original plate, the sealing performance,
It seems that there are differences in the corrosion resistance and flange crack resistance of the lid-wound portion. This relationship applies to a region where the micro Vickers hardness (X) inside the bottom ground contact portion is 190 or less.

According to the present invention, as described above, wrinkles are generated during the neck-in processing and flange processing is performed even though the thickness of the neck-in processed portion is thin and the tightening mouth portion is neck-in processed to have a small diameter. In addition, flange cracks (flange cracks) during winding tightening are prevented, and as a result, a steel drawn and ironed can having excellent sealing performance and corrosion resistance of the lid winding portion can be obtained.

[0022]

Preferred Embodiment of the Invention

[Drawing and ironing can] In FIG. 2 showing an example of the drawing and ironing can of the present invention, this drawing and ironing can 1 is formed by deep drawing (drawing-redrawing) of a steel plate such as tinplate and subsequent ironing, Broadly speaking, it consists of a bottom part 2 and a body part 3. The bottom portion 2 has substantially the same thickness as the base plate, and the body portion 3 has a side wall portion 4 which extends in the axial direction by drawing and is thinned by ironing.

A multi-step (four steps in the specific example shown in the figure) neck-in working part 5 is formed on the upper part of the side wall so that the diameter is gradually reduced. The winding fastening flange 6 is connected to the upper portion to form a reduced diameter mouth portion 7. The neck-in processing portion 5 is classified into a multi-stage shape and a smooth shape.

The bottom portion 2 has a tapered outer peripheral portion 8 whose diameter is reduced downward, a ground contact portion 9, a tapered inner peripheral portion 10 which rises sharply upward from the ground contact portion, and an inner peripheral portion. The dome portion 11 is connected to the bottom of the dome portion 11 to prevent the bottom from being deformed and improve the self-sustaining stability.

Assuming that the diameter of the side wall portion 4 of the body portion is D and the diameter of the mouth portion is d, the aperture reduction ratio R is represented by the equation R = (D−d) / D × 100. The aperture ratio is 15% or more, and preferably 16.0 to 24.0%, which is a high degree.

The neck-in start portion of the can body is shown in FIG.
In the present invention, the point P, that is, the neck-in processed portion of the first step is referred to. In the present invention, the plate thickness in the neck-in processed portion or in the vicinity thereof is in the range of 100 to 135 μm, preferably 110.
The thickness is extremely thin in the range of to 130 μm.

The distribution of the thickness of the can body before neck-in processing is enlarged and shown in FIG. In the conventional squeezed ironing can, even if the barrel side wall portion 4 is ironed to a considerably thin thickness (thickness t _S ), the neck-in processed portion 12 has a tapered portion 13 whose thickness increases upward. It is formed to be fairly thick (t _P ), and its thickness (t _P ) is generally 140 to 1
It is on the order of 50 μm. On the other hand, in the drawn and ironed can of the present invention, the neck-in processed portion 12 has the tapered portion 13
Even if they are connected via the, the degree of thickening is considerably small.

In the squeezed and ironed can of the present invention, the thickness (t _s ) of the body side wall portion is in the range of 75 to 90 μm, which is the same as that of a general squeezed and ironed can, or in the range of 50 to 75 μm, which is thinner. By making t _P thinner, the forming load at the time of necking can be made smaller, the can body plate thickness can be made thinner, which was not possible due to buckling, and the container can be made lighter. . For example, t _P is 100 to 130
With μm, t _S can be 50 to 75 μm. From another point of view, the thickness difference (t _p / t _s ) between the necked-in portion and the can body is 50 to 60 μm in the conventional case.
However, it is in the range of 20 to 60 μm. By making t _p thin as described above, the step can be reduced, and the can body can be easily removed from the punch after drawing and ironing.

For neck-in processing in the present invention, methods such as die neck, spin neck and squeeze neck can be used. In the case of a die neck, it is performed in a multi-step shape (generally a 4-step to 7-step shape in which the aperture ratio in one step is about 2 to 4%) or a smooth shape. In the case of the spin neck, the final shape is a smooth shape, but the spin neck may be performed after the die neck has been narrowed to some extent, or the spin neck may be performed in one step or in several steps.

In the present invention, in order to make the neck-in processed portion thin and improve the aperture ratio, the micro Vickers hardness (Y) at the neck-in start portion and its vicinity and the micro Vickers hardness (inside the bottom ground contact portion) ( X) is within the range defined by the formula X + Y ≦ 430, preferably X + Y ≦ 410, and Y ≦ 240, preferably Y ≦ 230.

The inside of the ground contact portion is the portion indicated by Q in FIG. 2, and the micro Vickers hardness of this inside contact portion Q is closely related to the workability of the steel material itself. The relationship between the micro Vickers hardness and the neck-in workability is as described in detail above. The materials used will be described in detail later.

The bottom shape of the drawn and ironed can of the present invention is formed by bottoming a flat bottom with a mold during or at the end of drawing and ironing. Regarding the shape and size of the bottom, the diameter (d _u ) of the grounding portion is generally smaller than the lid diameter by about 5 to 10 mm in consideration of stackability between cans and stackability and internal pressure resistance. Moreover, the height (HB) of the dome portion from the ground contact portion is about 20% of the diameter (d _u ) of the ground contact portion.

[Steel Material] The steel material used in the present invention is a surface-treated steel sheet having a cold-rolled steel sheet as a base material, and has a micro Vickers hardness (X) when formed into a drawn and ironed can.
And (Y) are within the above-mentioned range.

Generally, the hardness of a steel material is affected by both the hardness of the material itself and the work hardening that the material undergoes. That is, there is no doubt that the hardness of the cold-rolled steel sheet tends to increase as the cold rolling rate increases, but the hardness of the cold-rolled steel sheet is large or low even at a relatively low rolling rate. In addition, as the rolling rate increases, there are some with a remarkable increase in hardness and some with a relatively small increase in hardness, and their hardening characteristics vary widely. Factors that affect the hardness include the amount of components (the amount of interstitial solid solution elements such as carbon and nitrogen, the amount of substitutional solid solution elements such as manganese and phosphorus) and the amount of precipitates (such as cementite and other carbides and nitrides). Distribution state), grain size, etc., hot rolling conditions, annealing conditions, overaging treatment, secondary cold rolling amount,
It is well known that the characteristics of steel change greatly due to such factors. Further, in the can manufacturing process, heat treatments such as washing and drying and paint baking are indispensable, but the effect of age hardening in these heat treatments cannot be ignored.

As shown in the examples described later, cold rolling 20%
The micro Vickers hardness of the cross section after heat treatment at 210 ° C. for 5 minutes is 170 or less, and the micro Vickers hardness of the cross section after heat treatment at 210 ° C. for 5 minutes is 210 or less. It has been found that cold-rolled steel sheets having the following characteristics are suitable for the purpose of the present invention.

The cold-rolled steel sheet as the base material is preferably made of low carbon steel or ultra low carbon steel. In low carbon steel, the carbon content is generally 0.01 to 0.10% by weight, especially 0.01
To 0.06% by weight is desirable. As other components, those having a manganese content of 0.05 to 0.60% by weight, an aluminum content of 0.01 to 0.15% by weight, and a balance consisting of inevitable impurities and iron are particularly suitable. . Ultra-low carbon steel generally has a carbon content of 0.0005 to 0.
008% by weight, especially 0.0005 to 0.004% by weight
Is desirable. As other components, the manganese content is 0.05 to 0.60% by weight, and the aluminum content is 0.0.
It is particularly suitable that the content is 1 to 0.15% by weight and the balance consists of unavoidable impurities and iron, and that it contains 0.0005 to 0.04% by weight of Nb and / or Ti. Generally, regarding the steel in the present invention, a steel having a small amount of solute carbon is desirable. The reason is,
This is because solute carbon has a great influence on the work hardening as well as the hardness of the original plate. When the amount of solute carbon is large, both X and Y increase,
Defects are likely to occur in hermeticity. That is, it is possible to obtain the characteristics as in the embodiment by using the steels having these components and reducing the solid solution carbon.

The average crystal grain size in the cold-rolled steel sheet also has an important effect on its hardness, and the larger the grain size is, the generally softer the steel is. However, if the grain size is too large, necking becomes inhomogeneous. Average grain size is generally 8.0μ for low carbon steel
m or less, and 12.0 μm or less for ultra-low carbon steel is desirable.

The steel material used in the present invention is preferably a surface-treated steel sheet from the viewpoint of corrosion resistance and workability. As this surface-treated steel sheet, a cold-rolled steel sheet is annealed and then temper-rolled or Secondary cold rolling and one or more surface treatments such as zinc plating, tin plating, nickel plating, electrolytic chromic acid treatment, and chromic acid treatment can be used.

A preferred example of the surface-treated steel sheet is 0.7 to 15 g / m ² on the outer surface side of the can, particularly 0.7 to 5.6 g / m ^2.
m ^2, the can inner surface side is a tin plate having a tin plating amount of 0.0 to 15 g / m ^2, especially 0.0 to 5.6 g / m ^2. This tin plate may be a bright plate (reflow plate) having a tin-plated layer subjected to a melting treatment, or a mat plate (no reflow) having not been subjected to a melting treatment. In the former bright plate, a part of tin diffuses into the underlying iron to form a tin-iron alloy layer with the melting treatment,
This product is particularly excellent in corrosion resistance. The latter mat plate is one in which plated tin is attached in a granular form and is excellent in workability, that is, draw ironing workability. It is desirable that this tin plate has been subjected to chromate treatment, chromic acid / phosphoric acid treatment or phosphoric acid treatment so that the amount of chromium becomes 1 to 30 mg / m ^{2 in} terms of metal chromium.

Another example of a suitable surface-treated steel sheet is an electrolytic chromic acid-treated steel sheet, in particular, a metal chromium layer of 10 to 200 mg / m ² and a chromium oxide layer of 1 to 50 mg / m ² (metal chromium conversion). And is excellent in the combination of coating film adhesion and corrosion resistance. The base plate thickness of the steel plate is the same as that of a general steel drawn and ironed can, and a plate having a thickness of 0.24 to 0.32 mm can be used. Also, thinner than 0.17 to 0.23 mm can be used, and in this case it is lightweight and economical, and if the plate thickness of the neck-in part is the same, the processing amount from the original plate is smaller, so the neck The hardness of the in-start portion can be further reduced.

Still another example is aluminum plating,
An aluminum-coated steel plate subjected to aluminum pressure welding or the like is used. Further, a tin plate in which a thermoplastic resin is laminated on the inner surface side of the can is also used.

[Drawing and Ironing Forming] The drawing and ironing of the steel material can be carried out by a method known per se.
That is, this steel material is sheared into a shape such as a disk, and this is subjected to a single-stage or multi-stage drawing process between the drawing punch and the drawing die. The draw forming can be performed either by pre-drawing a large-diameter shallow cup or by deep-drawing a small-diameter deep-drawing cup. A slight ironing may be added to the part. A lubricant may be applied to the raw material at the time of drawing. Needless to say, the drawing process can be performed at room temperature, but the drawing process can be performed at a temperature slightly higher than room temperature.

In the above drawing process, the following formula (4) Generally, the aperture ratio defined by is preferably in the range of 1.2 to 2.0, particularly 1.3 to 1.9. The redrawing ratio defined in general is 1.1 to 1.6, especially 1.15.
It is preferably in the range of 1.5 to 1.5.

At the time of drawing and re-squeezing, various lubricants such as liquid paraffin, synthetic paraffin, edible oil, hydrogenated edible oil, palm oil, various natural waxes, polyethylene wax and synthetic ester are applied to a steel plate or a cup. It is better to carry out molding. The amount of lubricant applied varies depending on the type, but is generally 0.1 to 10
It is preferably in the range of mg / dm ² , particularly 0.2 to 5 mg / dm ² , and the lubricant is applied in the molten state by spray coating or roll coating on the surface.

The drawn or further redrawn cup is subjected to a single-stage or multi-stage ironing process using a combination of an ironing punch and an ironing die. During the ironing process, the clearance between the ironing punch and the ironing die is made smaller than the wall thickness of the cup side wall portion, whereby the side wall portion is stretched and thinned.

Formula (6) R _I = (t _b −t _s ) / t _b × 100 (6) In the formula, t _b is the thickness of the steel material before ironing, and t _s is after ironing. Is the thickness of the steel material,
The ironing rate (R _I ) defined by is preferably in the range of 2 to 60% in one step of ironing and 20 to 85% in the total ironing.

At the time of ironing, an ironing punch having a size and shape corresponding to FIG. 3 is used, and the thickness of the neck-in start portion or its vicinity is 100 to 135 μm and the micro Vickers hardness thereof satisfies the above formula. It goes without saying that ironing is performed.

After the ironing process is completed, the cup is preferably bottomed to form a dome on the bottom. Further, at the time of ironing, in order to lubricate and cool the ironing die and the side wall portion to be processed, it is preferable to spray an aqueous coolant on the processed portion for processing. As the aqueous coolant, the above-mentioned lubricant is dispersed in an aqueous medium together with a surfactant and emulsified. Alternatively, a water-soluble coolant such as synthetic ester is also used.

[Post-treatment] The obtained squeezed ironing cup is
After removing from the punch, perform pretreatment such as degreasing cleaning,
Then, a post-treatment such as surface treatment can be performed. Examples of this surface treatment include phosphoric acid treatment, chromic acid treatment, zirconic acid treatment, and treatment with a water-soluble polymer such as tannic acid and acrylic resin, which improve the corrosion resistance of the can and also improve the adhesion to the paint. To be The surface treatment of the squeezed and ironed can is easily performed by spraying the treatment liquid on the can. After the treatment, the can is washed with water, dried, and subjected to the following coating treatment.

As the protective coating, any protective coating composed of thermosetting and thermoplastic resins: modified epoxy coating such as phenol-epoxy coating, amino-epoxy coating and the like; vinyl chloride-vinyl acetate copolymer, chloride Vinyl-vinyl acetate copolymer partially saponified product, vinyl chloride-vinyl acetate-maleic anhydride copolymer, epoxy modified-,
Epoxyamino-modified or epoxyphenol-modified vinyl or modified vinyl coatings such as vinyl coatings; acrylic resin coatings; synthetic rubber coatings such as styrene-butadiene copolymers, or a combination of two or more thereof. It From the viewpoint of adhesion to steel and corrosion resistance, a paint containing an epoxy component as a part of the film-forming resin component is preferable.

These paints are used in the form of an organic solvent solution such as enamel or lacquer, or in the form of an aqueous dispersion or aqueous solution, such as roller coating, spray coating, dip coating, electrostatic coating, electrophoretic coating and the like. Shaped on metal material. Of course, when the resin paint is thermosetting, the paint is baked if necessary.

From the viewpoint of corrosion resistance and workability, the protective coating preferably has a thickness (dry state) of generally 2 to 30 μm, particularly 3 to 20 μm. Further, various lubricants may be contained in the coating film in order to improve the workability of the can after coating.

In the steel squeezed ironing can of the present invention, an aqueous paint can be used. That is, spray coating is generally used to form the inner surface protective coating, but using a water-based coating does not have the problem of solvent volatilization into the atmosphere, and is advantageous in terms of environmental protection and pollution prevention. To be The water-based coating material contains a carboxyl group-containing acrylic resin component and an epoxy resin component as at least a part of the coating film forming resin component, and the carboxyl group of the acrylic resin component is in the form of an ammonium salt or an amine salt. An emulsion thermosetting water-based coating composition in which the coating film forming resin component is present in the form of O / W emulsion particles is preferably used.

Although the baking of the paint varies depending on the kind of the paint, it is generally performed at a temperature of 180 to 210 ° C. for 30 hours.
It is performed for about 120 seconds. A hot air circulating furnace, an infrared heating furnace, or the like can be used for baking the paint.

[Neck-in Processing] According to the present invention, the thus-obtained coated can body is subjected to neck-in processing.
Neck-in processing, as already pointed out, has an aperture ratio of 1
It is carried out in one step or multiple steps so that it is 5% or more. At this time, it has already been pointed out that it is important that the micro Vickers hardness at or near the neck-in start portion is within a range that satisfies the above expressions (1) and (2). As the aperture stop, a die stop, a roller stop or a spatula stop can be used. Following neck-in processing, flange processing is performed using a flange die or a spin roll to obtain a final can body. When the neck-in processing is roller drawing, usually flange formation is also performed at the same time.

[0056]

The present invention will be described in more detail by the following examples.

The measurement and evaluation were carried out through Examples and Comparative Examples.
The evaluation was performed under the following conditions. 1) Number of out cans due to flange cracks during can making 1,000,000 cans of drawn and ironed cans were inspected with an inline flange crack detector, and evaluated by the number of out cans due to flange cracks. 2) Corrosion resistance evaluation of the lid-wound portion Squeeze iron can 10 after passing through the flange crack detector
Coca-Cola is filled and wound in 0 cans at 6 ℃ at 37 ℃
After storing it upright (with the lid facing upward), the corrosion score on the can body side of the lid winding part was investigated and expressed as the corrosion score per can. 3) Sealability evaluation Squeeze iron can 1 after passing through the flange crack detector 1.
Coca-Cola in 000 cans is filled and wound in a conventional manner at 37 ° C.
After storing it upside down for 1 year (with the lid facing down), the number of cans in which the liquid leaked from the lid winding part was checked.

[Example 1-1] The micro Vickers hardness of the cross section when heat-treated at 210 ° C for 5 minutes after cold rolling 20% was 175, and after cold rolling was 70% 210 ° C 5
Minute ultra-low carbon (0.0015 wt% carbon, box type annealed) steel sheet having a thickness of 0.220 mm and having a cross-sectional micro-Vickers hardness of 182, is tin-plated with E2.8. /2.8 tin-plated steel plate (tin)
Was manufactured. After blanking this steel plate to a blank diameter of 142 mm, after forming a cup with 1st drawing (drawing ratio 1.6), redrawing (drawing ratio 1.3) and ironing (3 steps)
And dome molding was performed, and the plate thickness at the neck-in start part was 0.
A squeezing and ironing cup with an inner diameter of 130 mm, which is 65.8 mm, is molded, trimmed to a height of 123 mm, washed, dried, printed on the outer surface, heat-baked, and then spray-painted on the inner surface and baked. After that, the neck equivalent part is reduced to an inner diameter of 52.4 mm (narrowing ratio of 20.4%) by a 6-step neck-shaped necking process using a die-neck method, then flanged, and the inner surface is spray-coated again. It was heated and baked to make a squeezed ironing can.

Regarding the drawn and ironed can thus obtained, the micro Vickers hardness (Y) at the neck-in start portion and the micro Vickers hardness (X) inside the bottom ground contact portion
And micro-Vickers hardness (Y) addition value at neck-in start part (X + Y), measured value of neck-in start part plate thickness, mouth draw ratio, etc., and evaluation of sealing property, corrosion resistance evaluation of lid wrapping part, can manufacturing The number of out cans was evaluated by the flange crack at that time. The results are shown in Table 1.

[Examples 1-2 to 1-6, Comparative examples 1-1 to 1-1]
1-3] Examples 1-2, 1-3, 1-4, 1-5, 1-
6, Comparative Examples 1-1, 1-2, 1-3, (cold rolling 20
% Vickers hardness after heat treatment at 210 ° C. for 5 minutes, cold rolling 70% at 210 ° C.
The cross-sectional micro Vickers hardness after heat treatment for 5 minutes is (183, 202) and (170, 21), respectively.
0), (198, 201), (170, 213), (1
96,217), (201,212), (171,22)
2), plate thickness 0.220 with characteristics of (220, 251)
Example 1 except that an E2.8 / 2.8 tin-plated steel plate (tin plate) was produced by tin-plating on a steel plate of mm.
A squeezed ironing can was produced in the same manner as in -1. The steel sheets at this time were ultra-low carbon (carbon content 0.0022% by weight, continuous annealing) steel sheet, low carbon (carbon content 0.037% by weight, continuous annealing) steel sheet, and ultra-low carbon (carbon content 0.0032 weight%). %, Continuous annealing steel sheet, low carbon (carbon content 0.032% by weight, continuous annealing) steel sheet, low carbon (carbon content 0.040% by weight, continuous annealing) steel sheet, ultra-low carbon (carbon content 0.0044% by weight) , Continuous annealing steel plate, ultra-low carbon (carbon content 0.0032)
% By weight, continuous annealed steel sheet, and low carbon (amount of carbon 0.051% by weight, continuous annealed) steel sheet. Regarding the drawn and ironed can thus obtained, in the same manner as in Example 1-1, the micro Vickers hardness (Y) at the neck-in start portion, the micro Vickers hardness (X) at the inside of the bottom ground contact portion, and the neck-in start portion Micro Vickers hardness (Y) addition value (X +
Y), measured values such as the plate thickness at the neck-in start part and the drawing ratio, the sealing property evaluation, the corrosion resistance evaluation at the lid winding part, and the number of out cans due to flange cracks during can making were evaluated. The results are shown in Table 1.

Example 2-1 On an extremely low carbon (0.0015 wt% carbon amount, box-type annealed) steel sheet having a plate thickness of 0.220 mm and having the same (rolling-hardness) characteristics as in Example 1-1. Tinning was performed to produce an E2.8 / 2.8 tinned steel plate (tin plate). After blanking this steel plate to a blank diameter of 142 mm, after forming a cup with 1st drawing (drawing ratio 1.6), redrawing (drawing ratio 1.3), ironing (3 steps) and dome forming, neck-in After forming a squeezing and ironing cup with a can body inner diameter of 65.8 mm having a plate thickness of 0.100 mm at the starting portion, trimming so that the can height becomes 123 mm, washing and drying, printing the outer surface and heating and baking. , The inner surface is spray-painted and heat-baked, and then the neck equivalent part is reduced to an inner diameter of 60.0 mm (narrowing ratio of 8.8%) by a necking process with a two-step neck shape using a die-neck method. Roll-neck type smooth inner diameter 52.4mm (first step inner diameter 56.2mm, total aperture reduction ratio 20.4%) diameter reduction and flanging processing, spray coating the inner surface again and heat bake, Diaphragm Ironing was produced cans.

With respect to the drawn and ironed can thus obtained, in the same manner as in Example 1-1, the micro Vickers hardness (Y) at the neck-in start portion, the micro Vickers hardness (X) inside the bottom ground contact portion and the neck-in Micro Vickers hardness (Y) addition value (X + Y) at the start, measured values such as neck-in start part plate thickness, mouth draw ratio, etc., and sealability evaluation, lid wrapping part corrosion resistance evaluation, canning flange The number of out cans due to cracks was evaluated. The results are shown in Table 1.

[Comparative Example 2-1] A drawn and ironed can was produced in the same manner as in Example 2-1 except that the plate thickness of the neck-corresponding portion was 0.095 mm. Regarding the drawn and ironed can thus obtained, in the same manner as in Example 1-1, the micro Vickers hardness (Y) at the neck-in start portion, the micro Vickers hardness (X) at the inside of the bottom ground contact portion, and the neck-in start portion Micro Vickers hardness (Y) addition value (X +
Y), measured values such as the plate thickness at the neck-in start portion and the draw ratio, the sealing property evaluation, the corrosion resistance evaluation of the lid winding portion, and the number of out cans due to the flange crack at the time of can making were evaluated. The results are shown in Table 1.

Example 3-1 On an extremely low carbon (0.0015% by weight carbon content, box-type annealed) steel sheet having a plate thickness of 0.220 mm and having the same (rolling-hardness) characteristics as in Example 1-1. Tin-plated E2.8 / 2.8 steel plate (tin plated) is tin-plated, and the neck-corresponding part is die-necked with a five-step neck-shaped necking process to obtain an inner diameter of 54.90 mm (ringing ratio 16. A squeezed iron can was produced in the same manner as in Example 1-1, except that the diameter was reduced to 6%.

With respect to the drawn and ironed can thus obtained, in the same manner as in Example 1-1, the micro Vickers hardness (Y) at the neck-in start portion, the micro Vickers hardness (X) inside the bottom ground contact portion and the neck-in Measured values such as added value (X + Y) of micro Vickers hardness (Y) at the start portion, plate thickness at the neck-in start portion, mouth draw ratio, etc. The number of out cans was evaluated by the flange crack. The results are shown in Table 1.

[Embodiment 3-2] The neck-corresponding portion is die-necked and the inner diameter is 60.0 m when the necking is performed in a two-stage neck shape
After reducing the diameter to m (perforation rate 8.8%), the diameter is reduced to 50.0 mm (first step 55.0 mm, total aperture rate 24.0%) with a smooth shape using a two-stage roll neck system. A squeezed and ironed can was produced in the same manner as in Example 3-1 except for the above.

With respect to the drawn and ironed can thus obtained, in the same manner as in Example 1-1, the micro Vickers hardness (Y) at the neck-in start portion, the micro Vickers hardness (X) inside the bottom ground contact portion and the neck-in Measured values such as added value (X + Y) of micro Vickers hardness (Y) at the start portion, plate thickness at the neck-in start portion, mouth draw ratio, etc. The number of rejects due to the flange crack was evaluated. The results are shown in Table 1.

[Example 3-3] A drawn and ironed can was produced in the same manner as in Example 3-2 except that the plate thickness of the neck-in start portion was set to 0.100 mm. Regarding the drawn and ironed can thus obtained, in the same manner as in Example 1-1, the micro Vickers hardness (Y) at the neck-in start portion, the micro Vickers hardness (X) at the inside of the bottom ground contact portion, and the neck-in start portion Micro Vickers hardness (Y) addition value (X +
Y), the measured values such as the plate thickness at the neck-in start portion and the mouth-drawing ratio, the sealability evaluation, the lid-wrapping portion corrosion resistance evaluation, and the number of rejects due to flange cracks during can making were performed. The results are shown in Table 1.

[0069]

[Table 1]

Examples 1-1 to 1-6, 2-1, 3-1 to
3-3, from Comparative Examples 1-1 to 1-3 and 2-1, a steel drawn and ironed can formed by drawing and ironing a steel plate and necking the winding mouth into a small diameter. The drawing ratio is 15% or more, the plate thickness at the neck-in start portion is in the range of 100 to 135 μm, and the micro-Vickers hardness Y at the neck-in start portion and the micro-Vickers hardness X at the inside of the bottom ground contact portion are expressed by the formula X + Y ≦ 430. It can be seen that the steel drawn and ironed can, which is characterized by being in the range defined by Y ≦ 240, has excellent sealing property, less corrosiveness at the winding portion, and excellent flange cracking property during can making.

Further, it can be seen that the quality of these cans is particularly excellent within the range defined by X + Y ≦ 410 Y ≦ 230.

FIG. 1 shows an example and a comparative example. The evaluation criteria for ○ △ x are as follows.

[0073]

As described above, according to the present invention, wrinkles are generated during neck-in processing even though the thickness of the neck-in processing portion is thin and the tightening mouth portion is neck-in processed to have a small diameter. Flange cracks (flange cracks) at the time of flanging and winding are prevented, and as a result, a steel drawn and ironed can having excellent sealing performance and corrosion resistance of the lid winding portion can be obtained. In addition, by reducing the thickness of the neck-in processing part, it is possible to reduce the weight of the can and reduce the material cost, and it is easy to remove it from the punch after ironing, so there are many advantages in terms of workability as well. To be achieved.

[Brief description of drawings]

[Fig. 1] Micro Vickers hardness (X) inside the bottom ground contact part
Is the horizontal axis, and the vertical axis is the micro-Vickers hardness (Y) at or near the neck-in start portion and the vertical axis, and the final drawing and ironing can sealability, corrosion resistance at the lid-wrapping portion, and flange crack resistance are evaluated as excellent (○ ), Good (Δ) and bad (x).

FIG. 2 is a partial cross-sectional side view showing an example of the squeezed ironing can of the present invention.

FIG. 3 is an enlarged cross-sectional view showing an enlarged distribution of the thickness of the can body before neck-in processing.

[Explanation of symbols]

 1 Squeeze ironing can 2 Bottom part 3 Body part 4 Side wall part 5 Neck-in processing part 6 Clamping flange 7 Reduced diameter part 8 Tapered outer peripheral part 9 Grounding part 10 Taper inner peripheral part 11 Dome part 12 Neck IN processing part 13 Tapered part

Claims (6)

[Claims] 1. A steel drawn and ironed can obtained by drawing and ironing a steel plate and necking-in a winding mouth into a small diameter, wherein the draw ratio is 15% or more, and the neck-in starting part or The plate thickness in the vicinity is 100 to 135
μm, and the micro Vickers hardness (Y) at or near the neck-in start portion and the micro Vickers hardness (X) inside the bottom ground contact portion are within the ranges specified by the formulas X + Y ≦ 430 and Y ≦ 240. A steel squeezing and ironing can with excellent sealing performance, corrosion resistance at the lid wrapping area, and flange crack resistance. 2. A steel drawn and ironed can obtained by drawing and ironing a steel plate and necking-in a winding mouth into a small diameter, wherein the draw ratio is 15% or more, and the neck-in starting portion or The plate thickness in the vicinity is 100 to 135
μm, and the micro Vickers hardness (Y) at or near the neck-in start portion and the micro Vickers hardness (X) inside the bottom ground contact portion are within the ranges defined by the formulas X + Y ≦ 410 and Y ≦ 230. A steel squeezing and ironing can with excellent sealing performance, corrosion resistance at the lid wrapping area, and flange crack resistance. 3. The steel drawn and ironing can according to claim 1, wherein the steel plate is an ultra-low carbon steel plate and the carbon content is 0.0005 to 0.0080% by weight. 4. The steel plate is a low carbon steel plate, and the carbon content is 0.010 to 0.060% by weight.
Steel squeezing ironing can. 5. The neck-in starting portion has a plate thickness of 100 to 13.
The drawn and ironed can made of steel according to claim 3, having a thickness of 0 μm and a can body plate thickness of 50 to 75 μm. 6. The original thickness of the steel plate is 0.17 to 0.
The steel squeezed ironing can of claim 5 having a size of 23 mm.