JP2748856B2 - Iron drawn iron can - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drawn ironing can made of steel, and more particularly, to a sealable, corrosion-resistant lid-tightened part having a small-diameter necked-in opening for a tightening opening. The present invention relates to a steel drawn and ironed can excellent in combination with flange crack resistance.

[0002]

2. Description of the Related Art A can body obtained by subjecting a metal material to a drawing and redrawing process between a punch and a die, and further ironing, has a seam at a connecting portion between a can body and a can body and a can bottom. It has the advantages of good appearance, no need for operations such as bottom cover winding and seam formation, and a thinner can body side wall that requires less metal material. From
Widely used for applications such as beverage canning.

[0003] Such two-piece cans are used for contents such as beer and carbonated beverages having autogenous pressure, cans filled with nitrogen, and canned by heat sterilization. Corrosion is required. Aluminum is a material with excellent workability and has the advantage that it can be highly thinned. However, compared to steel, aluminum has a strength that is one-third. Since steel is inferior in corrosion resistance to steel, steel cans are still used for applications requiring heat sterilization and for contents containing corrosive components.

In the case of a two-piece can, it is necessary to wind and tighten the easy-open lid at the flange portion at the upper part of the can body. In order to improve the appearance of the can body so as to be inside the outer periphery of the can body, neck-in processing is performed on the upper part of the can body to narrow the mouth to a small diameter. The neck-in processing has recently been required to be more advanced, that is, reduced to a smaller diameter by multi-step processing.

[0005]

However, in the case of a drawn and ironed can made of steel, reducing the thickness of the can body, including the neck-in processed portion, requires reduction in weight and cost of the can. Desirably, it has been found that such a thinned drawn ironed can often results in poor sealing performance of the wound portion and reduced corrosion resistance.

The inventors of the present invention have investigated the cause, and as a result, the above-mentioned poor sealing performance and reduced corrosion resistance are caused by the occurrence of wrinkles in the neck portion and the flange portion during neck-in processing. It was found out that cracks (flange cracks) were generated during the flange processing and the winding processing from the starting point. The occurrence of the wrinkles becomes more remarkable as the thickness of the neck-in start portion or the vicinity thereof becomes smaller, and tends to become more remarkable as the drawing ratio at the time of neck-in processing becomes larger.

Accordingly, an object of the present invention is to produce wrinkles during neck-in processing, flange processing, and the like, while the thickness of the neck-in processing part is thin and the winding opening is neck-in processed to a small diameter. An object of the present invention is to provide a steel drawn and ironed can that prevents flange cracks (flange cracks) during the tightening process and, as a result, has an excellent combination of sealing performance and corrosion resistance of a lid-tightened portion.

[0008]

According to the present invention, there is provided a steel drawn and ironed can which is formed by drawing and ironing a steel plate and necking in a small-diameter opening portion.
The aperture ratio is 15% or more, the plate thickness at or near the neck-in start portion is in the range of 100 to 135 μm, and the micro-Vickers hardness (Y) at or near the neck-in start portion and the inside of the bottom grounding portion. 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) The present invention provides a steel drawn and ironed can excellent in sealing performance, corrosion resistance of a wrapped portion of a lid, and resistance to flange cracks, which is within the range.

[0009]

Each measurement according to the present invention is performed by the following method. 1) Method of measuring micro-Vickers hardness (Y) of neck-in start part The micro-Vickers hardness (Y) of the neck-in start part is:
With respect to the neck-in start portion, eight cross-sectional micro-Vickers hardnesses (load 50 g, 30
S) and indicate the average value. 2) Measurement method of micro Vickers hardness (X) inside the bottom contact part The micro Vickers hardness (X) inside the bottom contact part is measured at every 45 ° in the circumferential direction of the can for the dome side arc-shaped part near the bottom contact part. The micro Vickers hardness at a cross section at eight points (load 50 g, 30 seconds) is measured and the average value is shown. 3) Method of measuring the thickness of the neck-in start portion The thickness of the neck-in start portion is determined by measuring the thickness of only the metal at 10 points in the circumferential direction of the can after peeling the inner and outer resin coatings of the neck-in start portion. The average value is shown. 4) Measuring of the squeezing rate The squeezing rate (%) is defined as in the following equation (3). Mouth drawing ratio (%) = ((inner diameter of can body-inner diameter of tightening portion) x 100) / inner diameter of can body ... (3)

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

Conventionally, in a drawn and ironed can, it is of course known that the thickness of the can body is reduced to the above-mentioned thickness by ironing. However, in a portion where neck-in processing or flange processing is performed, a flange free from wrinkles and cracks is formed. In order to form the portion, the degree of ironing of the portion was intentionally reduced, and the thickness thereof was generally about 140 μm.

On the other hand, in the present invention, a high ironing process is also applied to a portion where neck-in processing or flange processing is performed, and this portion is also made thinner, thereby reducing the weight of the can and reducing the material cost of the can. It is also aimed at reducing.

The reason why the plate thickness is limited to 100 to 135 μm is that the plate thickness at the neck-in start portion or in the vicinity thereof is 100 μm.
If it is less than μm, even if the requirements of the hardness of the can body described below satisfy the relationship of the present invention, when the mouth drawing ratio is 15% or more, the neck portion and the flange portion are formed at the time of necking and flanging. Defects such as wrinkles and microcracks occur, and the sealing performance, the corrosion resistance of the lid-tightened portion, and the resistance to flange cracking are reduced.

On the other hand, when the thickness of the neck-in start portion or the vicinity thereof exceeds 135 μm, defects during neck forming and flange forming with an opening ratio of 15% or more are generally small.
Good sealing performance, corrosion resistance of the lid winding part, and resistance to flange cracking, but the difference in plate thickness between the neck-in processing part and the can body part causes a step, and the can comes off from the punch during ironing. Property (strip-out property) worsens,
If the thickness of the neck-in processed part is large, the forming load during neck forming is large, so the can body is likely to buckle, the thickness of the can body cannot be reduced, and the amount of metal used in the can body increases, so economically The drawbacks are that it is disadvantageous, that the transportation cost is high due to the heavy weight of the can, and that it feels heavy when drinking and is disadvantageously intuitive.

The reason why the mouth drawing ratio is specified to be 15% or more is that the diameter of the easy-open lid to be wound around the can body is reduced, the cost of the lid is reduced, and the appearance characteristics of the whole can, particularly stability, etc. It is for improving.

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

Please refer to FIG. FIG. 1 shows the micro Vickers hardness (X) on the inner side of the bottom contact portion on the horizontal axis, and the micro Vickers hardness (Y) on the neck-in starting portion or in the vicinity thereof on the vertical axis. Evaluation of corrosion resistance and flange crack resistance was evaluated as excellent (○),
These are plotted as good (△) and bad (×).

According to the results shown in FIG. 1, a straight line X + Y = 4
In the region above 30 and Y = 240, poor sealing,
Corrosion of the lid winding portion, flange cracks, etc. occur, but in the region below these straight lines, these defects are effectively eliminated, and in particular, the straight lines X + Y = 410 and Y = 230
In the following areas, it is apparent that a drawn and ironed steel can be obtained which is particularly excellent in the combination of the sealing property, the corrosion resistance of the lid-wrapped portion, and the resistance to flange cracking.

If the value of (X + Y) is greater than 430,
The necking and the flange portion are apt to generate wrinkles due to the necking process, and cracks (flange cracks) are generated at the time of the flange processing starting from the wrinkles, so that the number of in-line reject cans increases and productivity decreases. Also, even if it does not break even during flange processing, if there is a large wrinkle in the flange part, the unevenness of the wrinkle part is large,
When it comes in contact with the lid when filling the contents, it rubs locally on the inner surface of the lid, the coating film is broken and the metal is exposed, so it is corroded by the filled contents, and in extreme cases, it becomes pitting corrosion, and the dissolved metal The flavor of the contents is deteriorated by the ions. In addition, the wrinkled portion of the flange is liable to become a flange crack at the time of double winding, which causes a reduction in sealing performance. In addition, wrinkles generated in the neck portion have a poor appearance, which leads to a reduction in commercial value of the can.

It should be understood that the absolute value (Y) of the micro-Vickers hardness at or near the neck-in start is also important. That is, the value of (X + Y) is 4
Even if it is 30 or less, there is a range in which the neck formability is poor, and the sealability, the corrosion resistance of the lid winding portion, and the flange crack resistance are inferior due to wrinkles and cracks in the flange portion and the neck portion. Although the reason for this is not clear, even if the hardness of the neck-in processed part is the same, the sealing property depends on the method of work hardening (depending on the type of steel base material) when the original sheet is drawn and iron-formed.
It is thought that there is a difference in corrosion resistance and flange crack resistance of the lid winding part. This relationship applies to the region where the micro Vickers hardness (X) inside the bottom contact portion is 190 or less.

According to the present invention, as described above, while the thickness of the neck-in processing portion is thin and the diameter of the fastening opening portion is reduced to a small diameter, generation of wrinkles during neck-in processing and flange processing In addition, a flange crack (flange crack) at the time of winding and clamping is prevented, and as a result, a drawn and ironed can made of steel having an excellent combination of sealing performance and corrosion resistance of a lid-tightened portion can be obtained.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION

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

In the upper part of the side wall portion, a multi-stage (four in the specific example shown in the figure) neck-in processing portion 5 is formed so as to gradually reduce the diameter. A winding flange 6 is connected to the upper part to form a mouth portion 7 having a reduced diameter. The neck-in processing portion 5 has a multi-stage shape and a smooth shape.

The bottom portion 2 has a tapered outer peripheral portion 8 whose diameter decreases downward, a ground contact portion 9, a tapered inner peripheral portion 10 which rises rapidly from the ground contact portion, and an inner peripheral portion. The dome portion 11 is connected to the dome portion to prevent deformation of the bottom and improve the self-standing 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 mouth drawing ratio R is represented by the formula R = (D−d) / D × 100. The aperture ratio is as high as 15% or more, preferably 16.0 to 24.0%.

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

FIG. 3 is an enlarged view of the thickness distribution of the can body before neck-in processing. In the conventional drawn and ironed can, even though the body side wall portion 4 is ironed to a considerably thin thickness (thickness t _S ), the neck-in processed portion 12 is formed via the tapered portion 13 whose thickness increases upward. It is formed to be quite 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 processing part 12 has a tapered part 13.
Even though they are connected via a thin film, the degree of the increase in the thickness is considerably small.

In the drawn 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 similar to that of a general drawn and ironed can, or in the range of 50 to 75 μm which is thinner. By reducing the thickness of t _P , the forming load during necking can be reduced, the thickness of the can body plate that could not be achieved due to buckling can be reduced, and the weight of the container can be reduced. . For example, t _{P is set} to 100 to 130.
Assuming μm, t _S can be set to 50 to 75 μm. From another viewpoint, the thickness difference (t _p / t _s ) between the neck-in processed portion and the can body is 50 to 60 μm in the conventional one.
Is in the range of 20 to 60 μm. Thus the t _p by thinning, it is possible to reduce the level difference, it is possible to improve the demolding from the punch the can body after the drawing and ironing.

In the neck-in processing in the present invention, a method such as a die neck, a spin neck, and a squeeze neck can be used. In the case of the die neck, it is performed in a multi-stage shape (generally, a four-stage to seven-stage shape in which the aperture ratio in one stage is about 2 to 4%) or a smooth shape. In the case of the spin neck, the final shape is a smooth shape, but it is also possible to perform the spin neck after performing a certain amount of aperture at the die neck, or to perform the spin neck in one or several stages.

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

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

The bottom shape of the drawn ironing can of the present invention is formed by bottoming out a flat bottom with a mold during or at the end of the drawing ironing process. Shape and dimensions of the bottom, considering the stackable property and internal pressure resistance is stackability of the can and the can, it is common that the diameter of the ground portion (d _u) is about 5~10mm smaller than Futa径. Further, the height (HB) of the dome portion from the ground portion is about 20% of the diameter (d _u ) of the ground portion.

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

In general, the hardness of a steel material is affected by both the hardness of the material itself and the work hardening of the material. That is, the hardness of the cold-rolled steel sheet is undoubtedly such that if the cold-rolling rate increases, the hardness tends to increase. In addition, there are those whose hardness is remarkably increased and those whose hardness is relatively small as the rolling reduction is increased, and the hardening characteristics thereof are various. Factors affecting the hardness include components (the amount of interstitial solid solution elements such as carbon and nitrogen, and the amount of substitutional solid solution elements such as manganese and phosphorus), and precipitates (the amount of carbides and nitrides such as cementite). And distribution state), crystal grain size, etc., hot rolling conditions, annealing conditions, overage treatment, secondary cold rolling amount,
It is well known that the properties of steel greatly change due to such factors. In the can making process, heat treatments such as washing and drying and baking of paint are indispensable, but the effects of age hardening in these heat treatments cannot be ignored.

As shown in the example described later, cold rolling 20%
The cross-sectional micro Vickers hardness after heat treatment at 210 ° C. for 5 minutes is 170 or less, and the cross-sectional micro Vickers hardness after cold rolling 70% and heat treatment at 210 ° C. for 5 minutes is 210 or less. A cold rolled steel sheet having the following characteristics was found to be suitable for the purpose of the present invention.

The cold-rolled steel sheet serving 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, particularly 0.01% by weight.
To 0.06% by weight is desirable. As the 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 the balance consisting of unavoidable impurities and iron are particularly suitable. . In ultra-low carbon steel, the carbon content is generally 0.0005 to 0.5%.
008% by weight, especially 0.0005 to 0.004% by weight
Is desirable. Other components have a manganese content of 0.05 to 0.60% by weight and an aluminum content of 0.0
Particularly suitable are those containing 1 to 0.15% by weight, with the balance consisting of unavoidable impurities and iron, and those containing 0.0005 to 0.04% by weight of Nb and / or Ti. Generally, as for the steel in the present invention, a steel having a low solid solution carbon is desirable. The reason is,
This is because solid-solution carbon has a large effect on work hardening as well as the original sheet hardness. When the amount of solid solution carbon is large, both X and Y increase,
Defects are easy to appear in sealing performance. That is, by using steel of these components and lowering the solute carbon, characteristics as in the examples can be obtained.

The average crystal grain size of the cold-rolled steel sheet also has an important effect on its hardness, and the steel having a larger grain size is generally softer. 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.

The steel material used in the present invention is preferably made of a surface-treated steel sheet from the viewpoint of corrosion resistance and workability. As the surface-treated steel sheet, after cold-rolled steel sheet is annealed, temper-rolled or It is possible to use one subjected to one or more surface treatments such as secondary cold rolling and surface treatment such as zinc plating, tin plating, nickel plating, electrolytic chromic acid treatment, and chromic acid treatment.

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

Another example of a preferred surface-treated steel sheet is an electrolytic chromic acid-treated steel sheet, particularly a chromium metal layer of 10 to 200 mg / m ² and a chromium oxide layer of 1 to 50 mg / m ² (in terms of chromium metal). This is excellent in combination of coating film adhesion and corrosion resistance. The original thickness of the steel plate is the same as that of a general steel drawn and ironed can, and a thickness of 0.24 to 0.32 mm can be used. In addition, a 0.17 to 0.23 mm thinner than the conventional one can be used. In this case, the weight is excellent and the economy is high. If the thickness of the neck-in portion is the same, the processing amount from the original plate is small. The hardness at the in-start portion can be made smaller.

Still another example is aluminum plating,
An aluminum-coated steel sheet subjected to aluminum pressure welding or the like is used. A tinplate obtained by laminating a thermoplastic resin on the inner surface side of the can is also used.

[Drawing and ironing] The drawing and ironing of a steel material can be performed by a method known per se.
That is, this steel material is sheared into a disk shape or the like and subjected to one-stage or multi-stage drawing between a drawing punch and a drawing die. Draw forming can be performed by pre-drawing into a large-diameter shallow cup and deep-drawing into a small-diameter deep-draw cup. In this deep-drawing process, the upper part of the cup side wall is used to make the wall thickness uniform. Light ironing may be added to the part. In drawing, a lubricant may be applied to the material. Of course, drawing can be performed at room temperature, but it is also possible to perform processing at a temperature slightly higher than room temperature.

At the time of drawing, the following formula (4) Is preferably in the range of 1.2 to 2.0, especially 1.3 to 1.9. Is generally 1.1 to 1.6, especially 1.15
It is preferably in the range of 1.5 to 1.5.

During drawing and re-pressing, various lubricants such as liquid paraffin, synthetic paraffin, edible oil, hydrogenated edible oil, palm oil, various natural waxes, polyethylene wax, and synthetic esters are applied to a steel plate or a cup. It is preferable to perform molding. The amount of the lubricant applied varies depending on the type, but generally ranges from 0.1 to 10
mg / dm ^2, good especially in the range of 0.2 to 5 mg / dm ^2, the application of the lubricant, which is performed by spray coating or roll coating to the surface in a molten state.

The drawn or redrawn cup is subjected to one or more stages of ironing using a combination of an ironing punch and an ironing die. At the time of ironing, by making the clearance between the ironing punch and the ironing die smaller than the thickness of the cup side wall, this side wall is stretched and thinned.

The following equation (6): R _I = (t _b −t _s ) / t _b × 100 (6) where t _b is the thickness of the steel material before ironing, and t _s is the thickness after ironing. The thickness of the steel material,
In ironing ratio defined (R _I) is 2 to 60% by ironing of one step, there is desirable in the range of 20 to 85% in ironing as a whole.

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

After the ironing, the cup is preferably bottomed to form a dome at the bottom. Further, at the time of ironing, in order to lubricate and cool the ironing die and the side wall to be processed, it is preferable to perform the processing by spraying an aqueous coolant onto the processing portion. As the aqueous coolant, those obtained by dispersing and emulsifying the above-described lubricant together with a surfactant in an aqueous medium are used. Alternatively, a water-soluble coolant such as a synthetic ester is used.

[Post-treatment]
After removing from the punch, perform pretreatment such as degreasing and washing,
Subsequently, a post-treatment such as a surface treatment can be performed. Examples of the surface treatment include a phosphoric acid treatment, a chromic acid treatment, a zirconic acid treatment, and a treatment with a water-soluble polymer such as tannic acid or an acrylic resin, which improve the corrosion resistance of the can and also improve the adhesion with the paint. Can be The surface treatment of the drawn and ironed can is easily performed by spraying the can with a treatment liquid. 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 a thermosetting or thermoplastic resin: for example, a modified epoxy coating such as a phenol-epoxy coating or an amino-epoxy coating; for example, vinyl chloride-vinyl acetate copolymer, chloride Vinyl-vinyl acetate copolymer partially saponified, vinyl chloride-vinyl acetate-maleic anhydride copolymer, epoxy-modified,
Vinyl or modified vinyl paints such as epoxyamino-modified or epoxyphenol-modified vinyl paints; acrylic resin-based paints; synthetic rubber-based paints such as styrene-butadiene-based copolymers, etc., alone or in combination of two or more. You. In terms 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 may be 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. Apply to metal material in form. Of course, if the resin coating is thermosetting, the coating is baked if necessary.

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

In the steel drawn ironing can of the present invention, a water-based paint can be used. In other words, spray coating is generally used for forming the inner surface protective coating, but when using a water-based coating, there is no problem of volatilization of the solvent into the atmosphere, and there are advantages in terms of environmental protection and pollution prevention. Can be The water-based paint contains a carboxyl group-containing acrylic resin component and an epoxy resin component as at least a part of the 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 emulsified thermosetting aqueous coating composition in which the film-forming resin component is present in the form of O / W emulsion particles is preferably used.

The baking of the paint varies depending on the kind of the paint, but is generally carried out at a temperature of 180 to 210 ° C. for 30 minutes.
For about 120 seconds. A hot air circulation furnace, an infrared heating furnace, or the like can be used for baking the paint.

[Neck-in processing] According to the present invention, neck-in processing is performed on the painted can body thus obtained.
In the neck-in processing, as already pointed out, the mouth drawing rate is 1
It is performed in one step or in multiple steps so as to be 5% or more. At this time, it has already been pointed out that it is important that the micro-Vickers hardness at the neck-in start portion or in the vicinity thereof is in a range satisfying the above formulas (1) and (2). A die drawing, a roller drawing or a spatula drawing can be used for the mouth drawing. Subsequent to neck-in processing, flange processing or the like is performed using a flange die or a spin roll to obtain a final can body. In the case where the neck-in process is a roller drawing, a flange is usually formed at the same time.

[0056]

The present invention will be described in more detail with reference to the following examples.

The measurement and evaluation were performed 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 canned and drawn iron 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 wrapped part of the lid The drawn iron can 10 after passing through a flange crack detector
Fill and wind Coca-Cola into a can using a standard method, and heat to 37 ° C.
After being stored in an upright position (the lid is in the upward direction), the number of corrosion points on the can body side of the lid-tightened portion was examined and expressed as the number of corrosion points per can. 3) Sealing evaluation Drawing and ironing can 1 after passing through flange crack detector
000 cans filled with Coca-Cola by standard method
After one year of storage, the number of cans in which the liquid leaked from the closed part of the lid was checked.

[Example 1-1] The cross-sectional micro Vickers hardness was 175 when subjected to a heat treatment at 210 ° C for 5 minutes after cold rolling was performed at 20%, and 210 ° C after 70% cold rolling.
Tin plating on an ultra-low carbon (0.0015 wt% carbon content, box-type annealed) steel sheet having a thickness of 0.220 mm and a micro Vickers hardness of 182 when subjected to heat treatment for 2.8 minutes. /2.8 tin-plated steel sheet (tinplate)
Was manufactured. After blanking this steel sheet to a blank diameter of 142 mm, forming a cup with the first drawing (drawing ratio 1.6), redrawing (drawing ratio 1.3) and ironing (3 steps)
And dome molding, and the thickness of the neck-in start portion is set to 0.
A drawn and ironed cup with a can body inner diameter of 65.8 mm, which is 130 mm, is trimmed to a can height of 123 mm, washed and dried, printed on the outer surface, heated and baked, then spray-coated on the inner surface and heated and baked. After that, the neck equivalent portion was reduced to an inner diameter of 52.4 mm (mouth drawing ratio: 20.4%) by a mouth drawing process of a six-stage neck shape by a die neck method, followed by flanging and spray coating the inner surface again. It was heated and baked to produce a drawn and ironed can.

With respect to the drawn and ironed can thus obtained, the micro-Vickers hardness (Y) at the neck-in start portion and the micro-Vickers hardness (X) at the inside of the bottom contact portion were obtained.
Value (X + Y) of the micro-Vickers hardness (Y) of the neck-in start part, the measured value of the neck-in start part plate thickness, the mouth drawing ratio, etc. The number of out cans was evaluated by flange cracking at the time. Table 1 shows the results.

[Examples 1-2 to 1-6, Comparative Examples 1-1 to 1]
1-3] Examples 1-2, 1-3, 1-4, 1-5, 1-
6, Comparative Examples 1-1, 1-2, and 1-3 correspond to (cold rolling 20
%, The cross-sectional micro Vickers hardness when heat-treated at 210 ° C. for 5 minutes, and 210 ° C. after 70% cold rolling.
The cross-sectional micro Vickers hardness after heat treatment for 5 minutes) was (183, 202) and (170, 21), respectively.
0), (198, 201), (170, 213), (1
96, 217), (201, 212), (171, 22)
2), a plate thickness of 0.220 having characteristics of (220, 251)
Example 1 except that a tin-plated steel plate (tinplate) of E2.8 / 2.8 was tin-plated on a steel plate of 2.5 mm.
In the same manner as in -1, a drawn and ironed can was prepared. At this time, the steel sheet is an ultra-low carbon (0.0022% by weight of carbon, continuous annealing) steel sheet, a low carbon (0.037% by weight of carbon, continuous annealing) steel sheet, and an extremely low carbon (0.0032% by weight of carbon). %, 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, extremely low carbon (carbon amount 0.0044% by weight) , Continuous annealing) steel plate, extremely low carbon (carbon content 0.0032)
Weight%, continuous annealing) steel sheet and low carbon (carbon content 0.051% by weight, continuous annealing) steel sheet. 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 contact portion, and the neck-in start portion Addition value of micro Vickers hardness (Y) (X +
Y), measured values of the neck-in starting portion plate thickness, the mouth drawing ratio, etc., the evaluation of the sealing performance, the evaluation of the corrosion resistance of the lid-tightened portion, and the evaluation of the number of out-cans due to flange cracks during can-making. Table 1 shows the results.

[Example 2-1] An extremely low carbon (0.0015% by weight of carbon, box-shaped annealed) steel sheet having the same (rolling-hardness) characteristics as that of Example 1-1 and having a thickness of 0.220 mm was prepared. Tin plating was performed to produce a tin-plated steel sheet (tinplate) of E2.8 / 2.8. After blanking this steel plate to a blank diameter of 142 mm, forming a cup with the first drawing (drawing ratio 1.6), redrawing (drawing ratio 1.3), ironing (3 steps) and dome forming, and neck-in After forming a drawn ironing cup having a can body inner diameter of 65.8 mm with a starting plate thickness of 0.100 mm, trimming the can to a height of 123 mm, washing and drying, printing the outer surface and heating and baking The inner surface is spray-painted and baked, and then the neck equivalent portion is reduced to an inner diameter of 60.0 mm (mouth drawing rate: 8.8%) by a two-necked mouth drawing process using a die neck method. The roll neck method is used to perform a smooth diameter reduction of 52.4 mm (the inner diameter of the first stage is 56.2 mm, the total opening ratio is 20.4%) and flanging processing, spray coating the inner surface again and heat bake, Aperture Ironing was produced cans.

With respect to the drawn and ironed can thus obtained, the micro-Vickers hardness (Y) at the neck-in start portion, the micro-Vickers hardness (X) inside the bottom contact portion and the neck-in hardness were determined in the same manner as in Example 1-1. Addition value (X + Y) of micro Vickers hardness (Y) at the start part, measured values such as neck-in start part thickness, mouth drawing ratio, sealing performance evaluation, corrosion evaluation of lid-tightened part, flange during can-making The number of out cans by cracking was evaluated. Table 1 shows the results.

[Comparative Example 2-1] A drawn and ironed can was manufactured in the same manner as in Example 2-1 except that the thickness of the neck equivalent portion was 0.095 mm. 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 contact portion, and the neck-in start portion Addition value of micro Vickers hardness (Y) (X +
Y), measured values such as the plate thickness at the neck-in start portion, the mouth drawing ratio, etc., the evaluation of sealing performance, the evaluation of the corrosion resistance of the lid-tightened portion, and the evaluation of the number of out-cans due to flange cracks during can-making. Table 1 shows the results.

Example 3-1 A very low carbon (0.0015% by weight of carbon, box-type annealed) steel sheet having the same (rolling-hardness) characteristics as that of Example 1-1 and having a thickness of 0.220 mm was formed. Tin-plated E2.8 / 2.8 tin-plated steel plate (tinplate) is manufactured by tin plating, and the neck equivalent part is 54.90 mm in inner diameter by a five-necked neck drawing process using a die neck method (mouth drawing ratio: 16.10 mm). Except that the diameter was reduced to 6%), a drawn and ironed can was produced in the same manner as in Example 1-1.

With respect to the drawn and ironed can thus obtained, the micro-Vickers hardness (Y) at the neck-in start portion, the micro-Vickers hardness (X) inside the bottom contact portion, and the neck-in were determined in the same manner as in Example 1-1. Addition value (X + Y) of micro-Vickers hardness (Y) at the start, measured values such as plate thickness at the neck-in start, mouth drawing ratio, etc. The number of out cans was evaluated by flange cracking. Table 1 shows the results.

[Embodiment 3-2] A neck-equivalent portion was formed by a two-neck neck drawing process using a die neck method and an inner diameter of 60.0 m.
m (mouth drawing rate 8.8%), and then reduced to a smooth inner diameter of 50.0mm (first-stage 55.0mm, total mouth drawing rate 24.0%) by a two-stage roll neck method. A wrung and ironed can was produced in the same manner as in Example 3-1 except that the procedure was performed.

With respect to the drawn ironing can thus obtained, the micro-Vickers hardness (Y) at the neck-in start portion, the micro-Vickers hardness (X) inside the bottom contact portion and the neck-in hardness were determined in the same manner as in Example 1-1. Addition value (X + Y) of micro-Vickers hardness (Y) at the start, measured values such as plate thickness at the neck-in start, mouth drawing ratio, etc. The number of rejects due to flange cracks was evaluated. Table 1 shows the results.

Example 3-3 A drawn and ironed can was manufactured in the same manner as in Example 3-2, except that the thickness of the neck-in start portion was set to 0.100 mm. 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 contact portion, and the neck-in start portion Addition value of micro Vickers hardness (Y) (X +
Y), measured values such as the plate thickness at the neck-in start portion, the mouth drawing ratio, etc., the evaluation of the sealing performance, the evaluation of the corrosion resistance of the lid-tightened portion, and the evaluation of the number of rejects due to flange cracks during can-making were performed. Table 1 shows the results.

[0069]

[Table 1]

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

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

An example and a comparative example are shown in FIG. The rating criteria of ○ △ × are as follows.

[0073]

As described above, according to the present invention, while the thickness of the neck-in processing portion is thin and the diameter of the winding-in opening portion is reduced to a small diameter, wrinkles during neck-in processing can be prevented. Flange cracks (flange cracks) at the time of flange processing and winding processing are prevented, and as a result, a drawn and ironed steel can excellent in combination of sealing performance and corrosion resistance of the lid-tightened 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 pull out from the punch after ironing, so there are many advantages in terms of workability. Achieved.

[Brief description of the drawings]

FIG. 1 Micro-Vickers hardness (X) inside the bottom contact part
The horizontal axis indicates the micro-Vickers hardness (Y) at or near the neck-in starting point, and the vertical axis indicates the evaluation of the sealability, corrosion resistance and flange crack resistance of the final drawn and ironed can. ), Good (△) and bad (×).

FIG. 2 is a partial cross-sectional side view showing an example of the drawn and ironed can of the present invention.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Drawing ironing can 2 Bottom part 3 Body part 4 Side wall part 5 Neck-in processing part 6 Flange for tightening 7 Reduced diameter mouth 8 Tapered outer peripheral part 9 Grounding part 10 Tapered inner peripheral part 11 Dome part 12 Neck In processing part 13 Taper part

Claims (6)

(57) [Claims] 1. A steel drawn and ironed can which is formed by drawing and ironing a steel plate and necking in a small-diameter opening for a winding, the mouth drawing rate is 15% or more, 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 contact portion are within the ranges defined by the formulas X + Y ≦ 430 and Y ≦ 240. A drawn and ironed steel can with excellent sealing properties, corrosion resistance of the lid winding part, and flange crack resistance. 2. A steel drawn and ironed can which is formed by drawing and ironing a steel plate and necking in a small-diameter opening for a winding, wherein the mouth drawing rate is 15% or more, and 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 contact portion are within the ranges defined by the expressions X + Y ≦ 410 and Y ≦ 230. A drawn and ironed steel can with excellent sealing properties, corrosion resistance of the lid winding part, and flange crack resistance. 3. The drawn and ironed steel can according to claim 1, wherein the steel plate is an ultra-low carbon steel plate and has a carbon content of 0.0005 to 0.0080% by weight. 4. The steel plate according to claim 1, wherein the steel plate is a low carbon steel plate, and the carbon content is 0.010 to 0.060% by weight.
Steel drawn ironing can. 5. A neck-in start portion having a thickness of 100 to 13
5. The drawn and ironed steel can according to claim 3, wherein the thickness is 0 μm and the thickness of the can body is 50 to 75 μm. 6. The steel sheet having an original thickness of 0.17 to 0.1 mm.
The steel drawn and ironed can according to claim 5, which is 23 mm.