JP5073931B2 - Two-piece can and manufacturing method thereof, and steel plate for two-piece can - Google Patents

Description

  The present invention relates to a two-piece can used as a container for various sprays such as an aerosol metal container.

  For example, in the field of metal containers for aerosols, there are roughly three-piece cans and two-piece cans. A three-piece can is a can body in which a rectangular flat plate is joined in a cylindrical shape, and a can bottom and a can lid (dome top) are attached. When used for spraying, a mounting cap provided with an injection valve is attached to the dome top (hereinafter referred to as an injection valve when referred to as a mounting cap in the present invention), including the mounting cap. In this case, the component member is composed of four elements. However, since beverage cans and food cans having a can body joined in a cylindrical shape are widely referred to as three-piece cans, the present invention can follow the above structure. Is called a three-piece can.

  On the other hand, a two-piece can has a diameter reduced at the opening end side of a can body formed into a bottomed cylinder, and a mounting cap is attached. In spray applications, the component is a single can body except for the mounting cap, so the can body itself may be called a one-piece can or monoblock can, but in beverage cans and food cans, it is formed into a bottomed cylinder. Since a thing provided with a can body is called two pieces widely, in the present invention, a can body having this structure is called a two piece can.

  The 2-piece can is a seamless can body, and the diameter of the 2-piece can is reduced in a continuous shape flowing from the can body to the mounting cap. Excellent. For this reason, two-piece cans are widely used in applications where the appearance of the package is important due to the nature of the product, such as fragrances, antiperspirants, hair styling agents, and the like. The cross-sectional shape of a two-piece can conventionally used is shown in FIGS. 1 shows that the cross-sectional shape of the bead portion is an arc shape, and FIG. 2 shows that the cross-sectional shape of the bead portion is a vertically long ellipse.

  The material used for the three-piece can and the two-piece can is a steel plate for the three-piece can, and aluminum for the two-piece can shown in FIGS. Aluminum is used as the material of the two-piece can because aluminum has better corrosion resistance than steel plate, so corrosion resistance to the contents and rust generation on the outside when the aerosol can is placed in a humid environment This is because it is difficult to become a problem. In contrast, steel sheets are high in strength and inexpensive. Therefore, when a steel plate is used for an aerosol can that requires high pressure strength, the thickness of the can body can be reduced while providing sufficient can body strength, and the material cost can be reduced. From the above points, a two-piece can using a steel plate with improved corrosion resistance has been demanded, and an attempt has been made to use a steel plate with improved corrosion resistance for a two-piece can.

  For example, as a method of obtaining a two-piece aerosol can using a steel plate with improved corrosion resistance, Patent Document 1 discloses a method of coating a steel sheet surface with a metal having high corrosion resistance, and Patent Document 2 discloses a method of coating the steel sheet surface with a coating film. Patent Document 3 discloses a method for coating, in which a method for coating a steel sheet surface with a film is disclosed.

  In addition, since aluminum is softer than a steel plate, for example, methods such as impact molding, drawing-redrawing, drawing-redrawing-ironing to obtain the shape of an aerosol can specified in Non-Patent Document 1. In the case of aluminum, it is relatively easy to form a bottomed cylindrical can body, further reduce the diameter of the opening end and process it into the shape of an aerosol can. In particular, in an aerosol can, a mounting cap is attached to the opening end portion of the can body, so that it is necessary to form a bead portion. When a steel plate having a work hardening degree higher than that of aluminum is used, cracks are likely to occur due to insufficient ductility when forming the bead part by curling, and it becomes very difficult to form the bead part.

In order to avoid such processing difficulties, Patent Documents 1, 5, and 6 disclose a method of providing a bead portion on the bottom side of the can, and Patent Document 7 discloses a method of improving the method of forming the bead portion. ing.
Japanese Unexamined Patent Publication No. 63-168238 JP-A-9-39975 Japanese Unexamined Patent Publication No. 1-228567 Japanese Patent Laid-Open No. 10-24973 Japanese Unexamined Patent Publication No. 64-62232 JP 2004-276068 A Japanese Patent Laid-Open No. 50-129474 Federation of European Aerosol Association Standard No.215, No.219, No.220

  Patent Document 1 that coats the surface of a steel plate with a metal having high corrosion resistance discloses a technique for avoiding rust at the bottom of a two-piece aerosol can that has been drawn and ironed by using an aluminum-coated steel plate. According to this method, there is a possibility that rust can be avoided at the bottom of the can with a low degree of processing. However, since the aluminum coating is damaged in the can body portion that has been drawn and ironed, the occurrence of rust is a concern. Patent Document 1 discloses a method of providing a bead portion on the opening end side of a can body made of a bottomed cylinder and a method of providing a bead portion on the bottom side of the can, but formation of a bead portion which is difficult with the conventional method. Is not described in particular.

  Patent Document 2 which is a method of coating a steel sheet surface with a coating film discloses a technique related to an inner surface coated metal container provided with a cured polyamideimide coating film. Although this technology is said to be able to use a steel plate as a material when used in a two-piece aerosol can, the examples relating to the steel plate are only related to a three-piece can with a low workability, and The corrosion resistance when processed into a high two-piece can is not described sufficiently, and the effect is unknown. The specification also states that this technique may be applied to a molded can body or may be applied to a metal plate before forming and processed later. However, even if it is applied to a two-piece can using aluminum shown in the examples, a coating film is formed after forming the can body, but it is applied to the metal plate before forming. An embodiment in which a film is formed and processed is not specifically shown. Therefore, as a result of the study by the present inventors, when a steel sheet coated with a heat-cured coating film is processed into a two-piece aerosol can having a high workability, the coating film is damaged by the processing, and sufficient corrosion resistance is obtained. was there. Further, only the two-piece can using aluminum is shown in the examples, and there is no disclosure regarding forming a bead portion using a steel plate.

  From the viewpoint of corrosion resistance, a method of covering the steel sheet surface with a film is promising. Patent Document 3 discloses a technique for obtaining an aerosol can using a steel plate laminated with a biaxially stretched film of polyethylene terephthalate. According to this technique, since the can body after drawing is covered with an undamaged laminate film, the corrosion resistance is excellent. However, the corrosion resistance of the can body obtained by this technology is maintained because the opening end of the can body is not reduced in diameter as shown in the examples and is defined in Non-Patent Document 1. No consideration has been given to corrosion resistance when applied to cans processed to the shape of aerosol cans. Similarly, it is not assumed that the bead is formed after the diameter of the can body is reduced.

  Patent Document 4 discloses a technique related to an aerosol can obtained by drawing a steel sheet obtained by laminating a composite film in which a polypropylene resin layer is laminated on both surfaces of a vinylidene chloride resin layer via an acid-modified polyolefin resin. Since this technique uses a steel sheet laminated with a film, it is considered that a can body excellent in corrosion resistance can be obtained. However, with regard to the drawing method, it is said that only an aerosol can with a 45 mm diameter × 120 mm high shape was obtained in the example, no specific processing method is described, and in particular, the opening end of the can body is reduced in diameter. There is no disclosure regarding the corrosion resistance and the formation of the bead part.

  Since it is difficult to form the bead portion at the opening end of the bottomed cylinder as described above, Patent Documents 1, 5, and 6 disclose a method of providing the bead portion on the bottom side of the can. The can bottom portion is a portion having a low degree of processing even during drawing, and since the work hardening of the material is small and the ductility is hardly deteriorated, it is relatively easy to form a bead portion in this portion. However, in this method, since the bottom of the can of another member is attached to the can body by tightening, the beauty of the two-piece can is lost, and this is not always a preferable method.

  Patent Document 7 discloses a method in which roll processing is performed from the diameter reduction on the opening end side of the can body to the formation of the bead portion. It is considered that the use of sequential deformation processing by roll processing is effective for forming itself because it is easy to avoid cracking of the bead portion. However, because of the sequential deformation, the rolling process is slow, and if a wide area including the reduced diameter part is rolled as in Patent Document 7, a long processing time is required, and the productivity of the can body deteriorates. There's a problem. Moreover, when a wide area like Patent Document 7 is rolled on a laminated steel sheet advantageous in terms of corrosion resistance and with a high degree of workability, there is a problem that the film is damaged by a roll machining tool.

  As described above, there has been no conventional method for forming a bead portion after reducing the diameter of a bottomed cylindrical can body using a laminated steel plate. Furthermore, when the cross-sectional shape of the bead portion is not a simple arc shape but a vertically long ellipse shape, it is more difficult to form the bead portion. Conventionally, when forming a bead portion having a vertically elliptical cross-sectional shape as shown in FIG. 2, a circular bead portion is formed by curling as a first step, and then as a second step. Has been reshaped into the desired oblong shape. FIG. 3 shows a conventional method for forming a vertically long elliptical bead portion. According to FIG. 3, the curvature radius of the first stage curl processing needs to be larger than the curvature of the vertically long ellipse, and the degree of processing at the tip of the curled portion increases, so that the portion tends to crack.

  In view of such circumstances, the present invention aims to obtain a two-piece can with sufficient strength of a can body and excellent corrosion resistance by using a laminated steel plate that is high in strength and relatively inexpensive and excellent in corrosion resistance. It is an object of the present invention to provide a molding method that can easily produce a two-piece can without cracking.

  As a result of researches to solve the above problems, the present invention has been completed by the following features. First, as a raw material for a two-piece aerosol can, a laminated steel plate having high strength, relatively low cost, and excellent corrosion resistance was used, so that the can body strength of the two-piece can was sufficient and the cost was low. And the formation of the bead part, which was difficult when using a steel plate as a raw material for a two-piece can, especially the forming when the cross-sectional shape of the bead part is not a simple arc shape, improved the structure of the bead part and the forming method Made it possible.

The present invention has been made based on the above findings, and the gist thereof is as follows.
[1] A two-piece can having a laminated steel plate as a raw material and having a bottomed cylindrical can body portion, the can body portion being reduced in diameter to a diameter smaller than the can body diameter,
And satisfies the following formulas (1) and (2),
Further, a two-piece can characterized in that a bead portion is formed on the opening side of the can body portion by curling the tip of the opening in the shape of an ellipse in cross section on the outside of the can.
1.5 ≦ h / (R−r) (1)
d / R ≦ 0.25 (2)
However, h: Height from can bottom to opening tip, R: Circular blank position radius, r: Bottom radius, d: Radius of opening tip [2] In [1], the bead portion is the opening A two-piece can characterized by being formed so that b1 / d ≦ 1.4 with respect to the radius d of the tip and the outer diameter b1 of the bead.
[3] The two-piece can according to [1] or [2], wherein the laminated steel plate is a steel plate coated with a polyester resin.
[4] In the above [3], the polyester resin is obtained by condensation polymerization of a dicarboxylic acid component and a diol component,
Furthermore, the dicarboxylic acid component is based on terephthalic acid,
The two-piece can characterized in that the diol component is mainly composed of ethylene glycol and / or butylene glycol.
[5] The organic resin coated on the laminated steel sheet contains the polyester resin according to [4] as a main phase, and the subphase contains a resin that is incompatible and has a Tg of 5 ° C. or less. 2 piece can.
[6] The two-piece can according to [5], wherein the resin contained as a subphase is a resin selected from the following.
Polyethylene, its acid-modified product, or ionomer polypropylene, its acid-modified product, or ionomer [7] A laminated steel sheet coated with an organic resin film, the two-piece can according to any one of [1] to [6] A laminated steel plate for a two-piece can, which is used for forming a steel sheet.
[8] A laminated steel plate is used as a material,
Forming a cylindrical can body with a bottom by drawing a circular blank multiple times,
The can body opening is reduced in diameter so as to be equal to or less than the can body diameter and satisfy the following formulas (1) and (2):
Furthermore, the opening end side of the can body portion is curled in a cross-sectional arc shape on the outside of the can to form a first curled portion, and then the opening end side of the first curled portion is pressed from above toward the bottom of the can. To form a second curled portion having a vertically long elliptical cross section.
1.5 ≦ h / (R−r) (1)
d / R ≦ 0.25 (2)
Where, h: height from the bottom of the can to the opening tip, R: radius of the circular blank position, r: radius of the bottom, d: radius of the opening tip [9] [8], the radius d of the opening tip And forming the bead part so that b1 / d ≦ 1.4 with respect to the outer diameter b1 of the bead part.
[10] The method for forming a two-piece can according to [8] or [9], wherein the laminated steel plate is a steel plate coated with a polyester resin.
[11] In the above [10], the polyester resin is obtained by condensation polymerization of a dicarboxylic acid component and a diol component,
Furthermore, the dicarboxylic acid component is based on terephthalic acid,
The method for forming a two-piece can, wherein the diol component is mainly composed of ethylene glycol and / or butylene glycol.
[12] The organic resin coated on the laminated steel sheet contains the polyester resin described in [11] as a main phase, and the subphase contains a resin that is incompatible and has a Tg of 5 ° C. or less. A method for forming a two-piece can.
[13] The method for forming a two-piece can according to [12], wherein the resin contained as a subphase is a resin selected from the following.
Polyethylene, its acid-modified product, or ionomer polypropylene, its acid-modified product, or ionomer

  According to the present invention, a two-piece can can be easily manufactured using a laminated steel plate as a raw material without causing cracks. And since the laminated steel plate excellent in corrosion resistance is used as a raw material, the obtained two-piece can is excellent in strength and excellent in corrosion resistance. Furthermore, the steel plate can be applied to the two-piece can, which has been difficult in the past, and the can cost can be reduced. In addition, the two-piece can of the present invention can easily form a bead portion necessary for attaching a mounting cap to the opening end of the can body, and is optimal as an aerosol can, for example.

  Hereinafter, the two-piece can of the present invention, the forming method thereof, and the steel plate for the two-piece can will be described in detail.

  First, the laminated steel plate used as a raw material in the present invention will be described.

  An object of the present invention is to obtain an inexpensive two-piece can having sufficient corrosion resistance and strength as a can body. Therefore, the material used for forming the two-piece can of the present invention is a laminated steel plate coated with an organic resin film excellent in workability and corrosion resistance in order to achieve the above-described object.

The type of the steel plate used in the present invention is not particularly limited as long as it can be formed into a desired shape, but the following components and manufacturing methods are preferable.
(1) Using low carbon steel having a C content of about 0.01 to 0.10% and recrystallized by box annealing.
(2) A low carbon steel having a C content of about 0.01 to 0.10% and recrystallized by continuous annealing.
(3) Recarbonized and over-aged by continuous annealing using low carbon steel with C content of about 0.01-0.10%.
(4) A low carbon steel having a C content of about 0.01 to 0.10%, which is subjected to secondary cold rolling (DR) after recrystallization annealing by box annealing or continuous annealing.
(5) An ultra-low carbon steel with a C content of approximately 0.003% or less and IF steel with a strong solid solution C-fixing element such as Nb, Ti, etc., and recrystallized by continuous annealing.
The mechanical properties of the steel sheet are not particularly defined as long as they can be formed into the desired shape, but the yield strength YP is about 220 MPa or more and 580 MPa or less in order to impair workability and maintain sufficient can body strength. It is desirable to use those. The r value that is an index of plastic anisotropy is desirably 0.8 or more, and the in-plane anisotropy Δr of the plastic anisotropy r value is desirably 0.7 or less in absolute value. The plate | board thickness of a steel plate can be suitably set from the shape of the target can and required can body strength. From the viewpoint of suppressing an increase in the cost of the steel plate itself and the can body, it is desirable to use approximately 0.15 to 0.4 mm.

And as for the said steel plate, it is desirable to use the surface treatment steel plate which gave various surface treatments to the surface. In particular, a surface-treated steel sheet (so-called TFS) or the like in which a two-layer coating composed of metallic chromium as the lower layer and chromium hydroxide as the upper layer is formed is optimal. The amount of adhesion of the metal chromium layer and chromium hydroxide layer of TFS is not particularly limited. However, in terms of Cr, both are 70 to 200 mg / m ² for the metal chromium layer and 10 to 30 mg / cm for the chromium hydroxide layer. A range of ² is desirable.

  Moreover, it is as follows about the organic resin film coat | covered on a steel plate.

  The organic resin film constituting the laminated steel sheet used in the present invention is preferably as follows for the purpose of eliminating the possibility of film damage due to processing as much as possible.

  For example, as an organic resin, polyester is more preferable because it has an excellent balance of elongation characteristics and strength characteristics necessary for processing. The polyester resin is obtained by condensation polymerization of a carboxylic acid component and a diol component. The dicarboxylic acid component is mainly composed of terephthalic acid, and the diol is mainly composed of ethylene glycol and / or butylene glycol. preferable. Further, when terephthalic acid is the main component as the dicarboxylic acid component, it is possible to include an isophthalic acid component as the other copolymerization component. When the diol component is mainly composed of ethylene glycol and / or butylene glycol, it can also contain diethylene glycol and cyclohexanediol as other copolymerization components. Furthermore, a resin having such a polyester resin as the main phase and an incompatible and Tg of 5 ° C. or less can be used as the subphase. In this case, the subphase is preferably selected from at least one selected from polyethylene, polypropylene, and / or acid-modified products thereof, or ionomers.

  In implementing this patent, additives such as pigments, lubricants and stabilizers may be added to the resin composition specified in this patent, or other functions may be added to the resin layer specified in this patent. You may arrange | position the resin layer which has these in an upper layer or an intermediate | middle layer.

  The method of laminating to the steel plate is not particularly limited, but is appropriately selected such as a thermocompression bonding method in which a biaxially stretched film or an unstretched film is thermocompression bonded, and an extrusion method in which a resin layer is directly formed on the steel plate using a T die. It has been confirmed that sufficient effects can be obtained.

The two-piece can of the present invention is made of the above laminated steel plate, and a circular blank is drawn a plurality of times to form a bottomed cylindrical can body, and then the opening side of the can body portion is defined as the can body. It is formed by reducing the diameter so as to satisfy the following formulas (1) and (2), and further forming a bead portion. In particular, in the present invention, when forming the bead portion, the opening tip side of the can body portion is curled in a cross-sectional arc shape outside the can to form a first curled portion, and then the opening tip including the first curled portion. By pressing the side from above in the direction of the bottom of the can, a bead portion having an oblong cross section is formed.
1.5 ≦ h / (R−r) (1)
d / R ≦ 0.25 (2)
However, h: Height from the bottom of the can to the opening tip, R: Circular blank position radius, r: Bottom radius, d: Radius of the opening tip The forming method is described in detail below.

Forming a bottomed cylindrical can body In order to form a bottomed cylindrical can body using a laminated steel plate as a raw material, a method of obtaining a predetermined height using a circular blank by drawing a plurality of times is suitable. . The number of times of drawing and the drawing ratio in a plurality of drawing processes can be selected as appropriate. In order to simplify the molding process, it is desirable to perform the drawing with a small number of times of drawing, but on the other hand, a low drawing rate, that is, severe processing is required. In order to simplify the molding process, a number of drawing times of 10 or less is desirable. The drawing ratio is desirably 0.4 or more when the first drawing is performed from the circular blank, and 0.5 or more in the subsequent drawing (redrawing) processing.

  Although the drawing in the present invention is based on drawing a plurality of times, a method of performing drawing-ironing with further ironing can be employed. Also, in multiple drawing processes, thinning drawing process that reduces the plate thickness by using bending / unbending deformation at the drawing die shoulder while applying back tension by wrinkle pressing force, and ironing this It is possible to adopt a method such as thinning drawing and ironing which uses processing together.

  Furthermore, the lubrication conditions influence the drawing process. The laminated steel sheet has a function of improving lubricity because the coated film is flexible and the surface is smooth. For this reason, it is not necessary to use a lubricant in the drawing process, but it is desirable to use a lubricant when the drawing rate is lowered. The type of lubricant can be selected as appropriate.

Further, along with the drawing process, the side wall thickness of the can body changes with respect to the original thickness. When the plate thickness change is expressed as the average plate thickness change rate t / t ₀ using the average plate thickness t and the original plate thickness t ₀ over the entire can height, t / t ₀ > 1 in the drawing-redrawing process. T / t ₀ <1 in drawing-ironing processing, thinning drawing processing, thinning drawing-ironing processing, and the like. Considering the damage of the laminated steel sheet due to processing, the average thickness change rate is preferably in the range of 0.5 <t / t ₀ <1.5.

For example, in an aerosol can, in order to attach a mounting cap to the opening of the can body, it is necessary to reduce the diameter of the opening end to a diameter smaller than the diameter of the cylinder. The degree of processing of the diameter reduction at this time can adopt the degree of processing to obtain a predetermined diameter necessary for attaching the mounting cap, but from the viewpoint of eliminating film damage as much as possible, the radius r of the can body, the diameter reduction It is desirable that d / r> 0.3 with respect to the radius d of the rear opening end, and more desirably, d / r> 0.4. The diameter reduction method includes a die neck method in which the opening end is pressed against an internally tapered die to reduce the diameter, and a rotating tool is pressed toward the can barrel opening end inward in the can cylinder radial direction to reduce the diameter. A method such as a spin neck method can be employed. From the viewpoint of eliminating film damage as much as possible, the die neck method is suitable. In the die-neck method, it is desirable to perform a process in which the range from the radius r of the can body to the radius d after the final diameter reduction is divided into a plurality of stages. At this time, if the degree of processing per process is large, the risk of wrinkling during diameter reduction increases, so the diameter reduction ratio (diameter after diameter reduction / diameter before diameter reduction) should be 0.9 or more. Is desirable. The laminated steel sheet has a function of improving lubricity because the coated film is flexible and the surface is smooth. For this reason, it is not necessary to use a lubricant in particular in the diameter reduction processing, but it is desirable to use a lubricant from the viewpoint of eliminating damage to the film due to sliding with the tool as much as possible. The type of lubricant can be selected as appropriate.

In addition, it is necessary to shape | mold so that the workability after diameter reduction processing may satisfy | fill following formula (1) and (2) here.
1.5 ≦ h / (R−r) (1)
d / R ≦ 0.25 (2)
However, h: Height from the bottom of the can to the opening tip, R: Circular blank position radius, r: Bottom radius, d: Radius of the opening tip First, height h to the opening end, bottom radius r, circular The blank position radius R is 1.5 ≦ h / (R−r). FIG. 4 shows the relationship between the can sizes.

  In actual drawing, drawing is performed from a circular blank having an initial blank radius R 'larger than the circular blank position radius R defined in the present application. The member between R and R ′ is removed by trimming. Here, h / (R−r) is an index representing the average elongation in the can height direction of the laminated steel sheet before and after forming.

  Next, d / R ≦ 0.25 with respect to the radius d of the opening tip and the circular blank position radius R. This is an index representing shrinkage in the circumferential direction of the laminated steel sheet before and after forming at the opening tip.

As described above, in order to form a bottomed cylindrical can body using a laminated steel plate as a raw material, a method of obtaining a predetermined height by drawing a circular blank a plurality of times is suitable. At this time, in order to obtain the shape of the aerosol can described in Non-Patent Document 1, and in order to avoid damage to the laminated steel sheet due to processing, the average thickness change rate is in the range of 0.5 <t / t ₀ <1.5. Therefore, it is necessary that h / (R−r) ≧ 1.5 and d / R ≦ 0.25.

Trimming after diameter reduction In processing where the opening side of the bottomed cylindrical can body is reduced to a diameter smaller than the diameter of the can body, the material is compressed in the circumferential direction. May occur. This unevenness has a risk of becoming a starting point of cracking in the subsequent curling for forming the bead portion. Therefore, it is effective from the point of prevention of cracking that the opening end portion which has been uneven in advance is cut out by trim processing to be a flat opening end portion. That is, by performing the trim processing after the diameter reduction, it is possible to avoid problems such as cracks at the time of forming the bead part.

In the present invention, in the present invention, the bead portion is curled in an arc shape in cross section on the outside of the can, and then the open tip portion of the curled portion is pressed from above in the direction of the bottom of the can so as to have an elliptical cross section. A feature is that a bead portion is formed. This is the most important requirement of the present invention. As a result, the bead portion is formed without cracking, and the formed bead portion has a vertically long cross section, so that the mounting cap can be clinched and fixed to the can body. As a result, it will fully function.

  When a steel sheet is can-formed with a very high degree of processing as in the prior art, the steel sheet is cured by work hardening and the ductility is deteriorated. Therefore, when the opening end is curled to form the bead portion, the opening end is cracked, and the bead portion cannot be formed after the bottomed cylindrical can body is reduced in diameter. .

  Therefore, in the present invention, when forming a vertically elongated elliptical bead section at the opening tip, a curl section having an arcuate section is formed, and then the opening tip of the curled section is pressed from above toward the bottom of the can. And found out a method of forming a bead portion having an oblong cross section. The forming process and shape of the bead portion according to the present invention are shown in FIG. According to FIG. 5, the first curl portion having a circular arc shape is formed by curling with a small curvature so that the opening end portion is not cracked, and then the opening tip portion of the first curl portion is the bottom portion of the can Press from above in the direction. The important point here is that the bead portion is formed by curling with a small curvature so that cracks do not occur at the opening end. In the case of forming a bead portion having a cross-sectional shape of a vertically long ellipse, conventionally, the arc-shaped bead portion is formed by curling as the first step, and then the second step is reshaped into the target vertically long oval shape. Molding. At this time, the radius of curvature of the first-stage curl processing needs to be larger than the curvature of the vertically long ellipse, and the degree of processing at the tip of the curl portion increases, so that the portion is more likely to crack. However, in the present invention, the first curl portion is formed by curling with a small curvature so that the opening end portion is not cracked. Therefore, in the conventional method, the arc-shaped bead portion is curled as the first step. Thus, it is possible to avoid cracks that occur when molding.

  In the present invention, when the first curl portion is formed, curl processing with a small curvature that does not cause cracking in the curl processing is performed. Specifically, the curling is preferably performed so that b1 / d ≦ 1.4 with respect to the radius d of the opening tip after the diameter reduction and the outer diameter b1 of the upper bead. When b1 / d> 1.4, cracks are likely to occur.

  The curling method can be either a die curl method in which the end of the can body is pressed against a curl die having an arcuate curved surface at the base of the cylindrical insert, or the end of the can body is pressed against a roll having an arcuate curved surface. A spinning method can be employed. As a representative example, an outline of molding by the die curl method is shown in FIG.

  As shown in FIG. 7, a method of pressing the first curled portion further by the curling method or the spinning method can be adopted as a method of pressing the opening tip of the first curled portion from above in the direction of the bottom of the can. . The curvature of the curved surface portion of the curl die used at this time can be the same as that used when forming the first curled portion. In order to reduce the pressing force of the curl die, it is also effective to make the curvature larger than the curvature at the time of forming the first curled portion. On the other hand, when the first curled portion is further pressed as shown in FIG. 8, the strength of the bead portion is increased by providing a circular arc-shaped portion formed by the first curl in the vertically elongated ellipse cross section. In addition, there is an advantage that the work of clinching the mounting cap to the bead portion becomes easy. In addition, after pressing a 1st curl part, a rotary roll can be further pressed from the outer side of a can body radial direction, and the cross-sectional shape of the whole bead part can also be adjusted.

  As shown in FIG. 6, the bead portion has a structure intended to clinching and fixing the mounting cap to the can body. Therefore, in the present invention, the cross-sectional shape of the bead portion is a vertically long oval shape. .

  Although the two-piece can of the present invention is obtained as described above, heat treatment and other processing during the processing steps described below can be performed as necessary.

Heat treatment in the middle of processing steps In the present invention, it is effective to further perform heat treatment in the middle of a series of processing steps as a method for further reducing the risk of film damage. That is, it is because the risk of film peeling in the subsequent processing is reduced by relaxing the stress accompanying the strain applied to the film in the processing by heat treatment. The heat treatment conditions for this purpose include a heat treatment at a temperature higher than the glass transition point of the film and a melting point + 30 ° C., and more preferably 150 ° C. or higher and a melting point + 20 ° C. or lower for the polyester film specified in this patent. ing. Furthermore, it is desirable to rapidly cool to a temperature below the glass point transfer of the film within 30 seconds immediately after the heat treatment, more preferably within 10 seconds. The purpose of the heat treatment is to relieve internal stress, and therefore heat treatment is required under conditions that relieve internal stress. From this point of view, the glass transition point is set as the lowest temperature at which internal stress can be relaxed, and this is the lower limit of this regulation. Further, for the polyester resin of the present invention, 150 ° C. is set as a lower limit value of a desirable heat treatment temperature. This is the lower limit of the temperature at which processing can be performed for a short time with respect to relaxation of internal stress. That is, if the glass transition point or higher, internal stress can be relieved, but if it is 150 ° C. or higher, processing in a short time is possible. The upper limit of the heat treatment temperature is defined in consideration of degradation due to thermal decomposition of the resin. If the melting point is in the range of + 30 ° C., preferably + 20 ° C., resin degradation due to thermal decomposition is not a problem.
The heat treatment method is not particularly limited, and it has been confirmed that the same effect can be obtained with an electric furnace, a gas oven, an infrared furnace, an induction heater, or the like. Further, the heating rate and the heating time may be appropriately selected according to the effect, but the higher the heating rate, the more efficient, and the standard heating time is about 15 to 60 seconds, but is limited to this range What is necessary is just to select suitably according to an effect rather than a thing.

Other Processing The aerosol can targeted by the present invention requires a pressure strength of 15 kgf / cm ² or more in order to fill with a propellant. It is necessary to pay particular attention to the bottom of the can against the pressure increase inside the can. The pressure inside the bottomed cylindrical can body acts on the side wall of the can body portion in the direction of expanding the can body in the circumferential direction. However, the can body member is sufficiently work-hardened by drawing and is not deformed by the action of the internal pressure. It is the bottom of the can that needs to consider the effect of internal pressure. Since the inner pressure acts on the bottom of the can with the outer edge being constrained by the can body, when the inner pressure is high, the can bottom is deformed toward the outside of the can. In order to suppress deformation of the bottom of the can due to internal pressure, a method of increasing the strength of the member by increasing the thickness of the bottom of the can is effective, and in addition, the shape is a dome shape that is recessed inside the can body Is suitable.

  In addition, the structure of the bead part designated by this invention is not limited to the case where the material of a can body uses a laminated steel plate, It can apply also when using another raw material.

Example 1
A steel sheet obtained by laminating 0.025 mm polyethylene terephthalate film on both sides of TFS using a low-carbon steel cold-rolled steel sheet with a thickness of 0.20 mm obtained by continuous annealing, and an initial blank radius R '= 42 mm. Then, drawing was performed with a drawing ratio of about 0.6. Next, redrawing with a drawing ratio of about 0.8 was performed four times to form a bottomed cylindrical can body having a can body radius r = 11 mm. After forming the dome part that is depressed inside the can body at the bottom of the can by overhanging, heat treatment is applied to the can body at 220 ° C for 30 seconds, and the opening end of the can body is trimmed, and then the die neck method is used to reduce the size. The diameter reduction processing was performed to the opening radius d = 7.5 mm after the diameter reduction by performing the diameter reduction processing with a diameter ratio of about 0.95 a plurality of times. The opening tip after the diameter reduction was further trimmed to form a can body having a height h = 65.5 mm from the bottom of the can. At this time, the circular blank position radius R = 40.3 mm, the processing degree d / R = 0.19 in the circumferential direction defined in the present invention, and the processing degree h / (R−r) = 2.24 in the height direction.

  A first curl portion was formed on the can body by a die curl method in which a curl die having an arcuate curved surface portion having a radius of 1.0 mm is pressed on the base portion of the cylindrical insert by a die curl method. At this time, the tip end radius b1 = 9 mm of the outer diameter of the curl portion was set to b1 / d = 1.3. Furthermore, the top end side of the opening of the first curl portion is viewed from the top in the direction of the bottom of the can by a die curling method in which the end of the can body opening is pressed against a curl die having an arc-shaped curved surface with a radius of 1.25 mm at the base of the cylindrical insert. The outer diameter b2 of the bead portion was set to 10 mm. At this time, the bead height, which is the height from the upper end to the lower end of the bead portion, was set to 4 mm.

In the above molding process, no cracks occurred during the molding of the bead portion. Further, as a result of storing the molded can body at 50 ° C. and 98% RH for 1 month, no rust was generated. As described above, the can body according to the present invention did not generate cracks in forming the bead portion, and exhibited sufficient corrosion resistance even in a humid environment.
(Comparative example)
In addition, a low carbon steel cold-rolled steel plate with a thickness of 0.20 mm obtained by the continuous annealing method is used as a base plate, and a steel plate obtained by laminating 0.025 mm polyethylene terephthalate film on both sides of the TFS by the heat-sealing method, the initial blank radius R After forming a = 42 mm circular blank, drawing was performed at a drawing ratio of about 0.6. Next, redrawing with a drawing ratio of about 0.8 was performed four times to form a bottomed cylindrical can body having a can body radius r = 11 mm. After forming the dome part that is depressed inside the can body at the bottom of the can by overhanging, heat treatment is applied to the can body at 220 ° C for 30 seconds, and the opening end of the can body is trimmed, and then the die neck method is used to reduce the size. The diameter reduction processing was performed to the opening radius d = 7.5 mm after the diameter reduction by performing the diameter reduction processing with a diameter ratio of about 0.95 a plurality of times. The opening tip after the diameter reduction was further trimmed to form a can body having a height h = 72 mm from the bottom of the can. After further trimming the opening tip after diameter reduction, the tip end radius is pressed by a die curl system that presses the can barrel opening end against a curl die having an arc-shaped curved surface with a radius of 2.1 mm at the base of the cylindrical insert. Curling was performed so that b3 = 11.7 mm. At this time, a crack occurred at the open end of the can body, and the bead portion could not be formed.

  The two-piece can of the present invention is optimal as a two-piece aerosol can because of its excellent performance. In addition to the two-piece aerosol can, it is also suitable for applications requiring can body strength, corrosion resistance, appearance, and low cost.

It is the side and longitudinal cross-sectional view about the conventional 2 piece can made from aluminum. It is the side and longitudinal cross-sectional view about the conventional 2 piece can made from aluminum. It is a figure which shows the formation method of a bead part about the conventional 2 piece can. It is a figure which shows the relationship of the can body size of this invention. It is a figure which shows a bead part about the 2 piece can of this invention. It is the side and longitudinal cross-sectional view which show the state which clinched the mounting cap to the bead part about the 2 piece can of this invention. It is a figure which shows the shaping | molding method of the bead part by a die curl system. It is a figure which shows a bead part about the 2 piece can of this invention.

Explanation of symbols

1 Can body 2 Mounting cap 3 Valve for injection 4 Bead part 5 Circular blank before processing 6 Curl die

Claims (13)

The laminated steel sheet as a material, have a bottomed cylindrical can body portion, a two-piece can with a mounting cap, the can body is reduced in diameter the opening side to a diameter smaller than the can body diameter And
And satisfies the following formulas (1) and (2),
Furthermore, on the opening side of the can body,
Before the mounting cap is attached , a bead portion is formed by curling the tip of the opening to the outside of the can in the shape of a vertically elongated ellipse. The bead portion has a first curled portion having a circular arc shape in cross section and a second elliptical cross section. A two-piece can comprising a curl portion.
1.5 ≦ h / (R−r) (1)
d / R ≦ 0.25 (2)
However, h: Height from the bottom of the can to the opening tip, R: Circular blank position radius, r: Bottom radius, d: Radius of the opening tip 2. The two-piece can according to claim 1, wherein the bead portion is formed to satisfy b1 / d ≦ 1.4 with respect to a radius d of the opening tip portion and an outer diameter b1 of the bead portion. The two-piece can according to claim 1 or 2, wherein the laminated steel plate is a steel plate coated with a polyester resin. The polyester resin is obtained by condensation polymerization of a dicarboxylic acid component and a diol component,
Furthermore, the dicarboxylic acid component is based on terephthalic acid,
The two-piece can according to claim 3, wherein the diol component contains ethylene glycol and / or butylene glycol as a main component. The organic resin coated on the laminated steel sheet is a two-piece can characterized in that the polyester resin according to claim 4 is used as a main phase, and the subphase contains a resin that is incompatible and has a Tg of 5 ° C or lower. . The two-piece can according to claim 5, wherein the resin contained as a subphase is a resin selected from the following.
Polyethylene, its acid-modified product, or ionomer polypropylene, its acid-modified product, or ionomer A laminated steel sheet coated with an organic resin film, wherein the two-piece can laminated steel sheet is used for forming the two-piece can according to any one of claims 1 to 6. A laminated steel plate is used as a raw material, and a circular blank is drawn multiple times to form a bottomed cylindrical can body, and the opening of the can body is equal to or less than the diameter of the can body, and the following formula (1) and formula The diameter is reduced so as to satisfy (2), and further, the front end side of the can body is curled in a cross-sectional arc shape outside the can before attaching the mounting cap to form a first curled portion, By pressing the opening front end side of the first curl portion in the direction of the bottom of the can from above, the cross-sectionally elongated ellipse is provided with a cross-sectional arc-shaped portion formed by the first curl in the cross-sectionally elongated ellipse. A method for forming a two-piece can, comprising forming a second curled portion having a shape.
1.5 ≦ h / (R−r) (1)
d / R ≦ 0.25 (2)
However, h: Height from the bottom of the can to the opening tip, R: Circular blank position radius, r: Bottom radius, d: Radius of the opening tip 9. The method for forming a two-piece can according to claim 8, wherein the bead portion is formed such that b1 / d ≦ 1.4 with respect to the radius d of the opening tip portion and the outer diameter b1 of the bead portion. The method for forming a two-piece can according to claim 8 or 9, wherein the laminated steel plate is a steel plate coated with a polyester resin. The polyester resin is obtained by condensation polymerization of a dicarboxylic acid component and a diol component, and the dicarboxylic acid component is mainly composed of terephthalic acid,
The method for forming a two-piece can according to claim 10, wherein the diol component contains ethylene glycol and / or butylene glycol as a main component. The two-piece can characterized in that the organic resin coated on the laminated steel sheet contains the polyester resin according to claim 11 as a main phase and a subphase containing a resin that is incompatible and has a Tg of 5 ° C or less. Molding method. The method for forming a two-piece can according to claim 12, wherein the resin contained as a subphase is a resin selected from the following.
Polyethylene, its acid-modified product, or ionomer polypropylene, its acid-modified product, or ionomer

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