JP2023102644A - Bottle-shape can, and roughly-shaped material for bottle-shape can - Google Patents

Abstract

To provide a bottle-shape can capable of reducing thickness or weight, that prevents a problem from occurring during opening of a cap, even when performing roll-on capping; and to provide a roughly-shaped material therefor.SOLUTION: There is provided a bottle-shape can 1 made from an aluminum alloy, whose cylindrical neck part 5 is continuously formed at an upper end central part of a shoulder part 4 with a tip part of the neck part 5 made to be a curl part 7, whose male screw part 8 is formed at a lower side portion of the curl part 7 out of the neck part 5, and whose protrusion bead part 9 is formed at a lower side portion of the male screw part 8, while the shoulder part 4 whose diameter gradually becomes smaller is continuously connected to a cylindrical trunk part on an upper side. The curl part 7 has an inner diameter of 30 mm or more. A height as a size measured in an axial direction of the curl part 7 is 1.9 mm or more and 2.0 mm or less. A thickness as a size measured in a radial direction of the curl part 7 is 1.2 mm or more and 1.4 mm or less. A wall thickness t7 of the curl part 7 is thicker than a wall thickness t8 of the male screw part 8.SELECTED DRAWING: Figure 4

Description

TECHNICAL FIELD The present invention relates to a bottle-shaped metal can made of aluminum alloy, and more particularly to a so-called resealable bottle-shaped can with a cap attached by a screw, and a raw material used to manufacture the bottle-shaped can.

An example of this type of bottle-type can is described in Patent Document 1. The bottle-type can described in Patent Document 1 is a so-called two-piece can in which a body and a bottom are integrally formed by drawing and ironing a thin metal plate, and a male threaded portion is formed in the neck (or neck) that is provided continuously from the upper part of the body. The portion on the tip side from the male screw portion is the mouth portion, and the edge portion (peripheral edge portion) thereof is curled outward. In addition, a bead portion that protrudes outward in a band shape is formed in a portion that continues to the lower side of the threaded portion.

The cap that seals this bottle-shaped can is attached by a method called roll-on capping. That is, a simple cylindrical cap rough shape having approximately the same diameter as the mouth and neck is put on the mouth and neck, and the corner of the cap rough is pressed against the opening end of the curled mouth. At the same time, the lower end portion of the cap rough-shaped member (the lower end portion of the Pilfer proof band portion) is squeezed and deformed so as to embrace the bead portion from below. Therefore, during this roll-on capping, a pressing force (referred to as plugging force) is applied to the mouth and neck from above. If the bottle-shaped can is made thinner in order to reduce the weight and the amount of material used, the strength of the neck portion and the portion extending from the neck portion to the body portion is reduced, and there is a risk of buckling due to the aforementioned plugging force. In order to solve such a problem, the bottle-type can described in Patent Document 1 processes the portion connected to the lower side of the bead portion so that the cross-sectional shape thereof forms an "S" shape, thereby increasing the rigidity or strength of the portion where buckling is likely to occur.

Japanese Patent No. 6817106

Briefly explaining the above roll-on capping, FIG. 1 schematically shows a state in which general roll-on capping is performed. A bottle-shaped can 100, which is an object to be capped, has a shoulder portion 102 connected to the upper side of its body portion 101. The shoulder portion 102 is a tapered or dome-shaped portion whose upper side is drawn, and is formed by drawing a portion connected to the body portion 101 . A mouth and neck portion 103 is continuous with the upper end portion of the shoulder portion 102 . An axially intermediate portion of the mouth/neck portion 103 is threaded to form a male thread portion 104 . The upper end of the mouth and neck portion 103 is open and serves as a mouth portion, and the peripheral portion thereof is curled outward to form a curl portion 105 . Further, a bead portion 106 is formed on the lower side of the screw portion 104 so as to protrude outward in a strip shape. Note that the bead portion 106 is sometimes called a turnip portion because of its shape.

A cap rough shape member 107 attached to the mouth/neck portion 103 has a simple cylindrical shape (cap shape) having a bottom portion (or a top plate portion) and covers the mouth/neck portion 103 from above. The cap rough shape member 107 is pressed from above toward the curled portion 105 by the pusher block 108 , and at the same time, the corner portion of the cap rough shape member 107 is crushed so as to be in close contact with the curled portion 105 . On the other hand, a thread forming roll 109 is arranged on the outer peripheral side of the male threaded portion 104, and the thread forming roll 109 revolves while pressing the cylindrical portion of the cap raw material 107 against the male threaded portion 104, and in this way, the cylindrical portion of the cap raw material 107 is processed into an internal thread along the male threaded portion 104. In parallel with the threading, the hem tightening roll 110 pushes the lower end portion of the cap rough shape member 107 toward the lower side of the bead portion 106, and as a result, the portion corresponding to the Pilfer proof band wraps the bead portion 106 from below and engages.

When roll-on capping is performed in this way, the pusher block 108 presses the cap rough shape member 107 from above, so that a so-called plugging force is applied downward to the bottle-shaped can 100, which causes buckling. In the invention described in Patent Document 1, the buckling strength is increased by forming the above-described "S"-shaped cross section. However, the mouth/neck portion 103 is subjected to a radially inward load as a result of threading by the thread forming roll 109 , and the load acts to crush the mouth/neck portion 103 . FIG. 2 explains the situation, three thread forming rolls 109 are arranged at equal intervals on the outer peripheral side of the mouth/neck portion 103, so that the portion of the mouth/neck portion 103 pushed by the thread forming rolls 109 bends inward, and the portion between these portions bends outward as shown by the dashed line in FIG. The bent portion sequentially moves in the revolution direction of the thread forming roll 109 as the thread forming roll 109 revolves in the direction indicated by the arrow in FIG. When the thread forming roll 109 is separated from the mouth/neck portion 103 in the radial direction after the threading is completed, the deformation occurring in the mouth/neck portion 103 at that time remains as it is, or the deformation after a slight springback remains in the mouth/neck portion 103. This deformation is sometimes referred to as oval deformation because the neck portion 103 is slightly elliptical. Therefore, in the bottle-shaped can 100 with such deformation, when the cap is turned to be opened, rubbing occurs between the cap and the neck portion when the short axis of the ellipse passes over the long axis. In addition, the cap is tilted over the mouth and neck portion 103, and as a result, the degree of close contact between the sealing material on the inner surface of the cap and the curled portion 105 may be impaired, and the contents may leak out. Conventionally, as described in Patent Document 1, countermeasures against the plugging force during roll-on capping have been studied, but the oval deformation of the mouth and neck has not been studied, and there is still room for improvement.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a bottle-type can and a rough shape thereof which can be made thin or light in weight and which can be opened without defects even when roll-on capping is performed.

In order to achieve the above object, the present invention is made of an aluminum alloy, in which a shoulder portion whose diameter gradually decreases upward is continuously formed on the upper end side of a cylindrical body portion, a cylindrical mouth and neck portion is continuously formed in the center of the upper end of the shoulder portion, the tip portion of the mouth and neck portion is formed as a curl portion that bends outward, and a male screw portion is formed in a lower portion of the curl portion of the mouth and neck portion, and a bead portion that protrudes outward is formed in a lower portion of the male screw portion. In the bottle-shaped can, the inner diameter of the curled portion is 30 mm or more, the height of the curled portion measured in the axial direction is 1.9 mm or more and 2.0 mm or less, the thickness of the curled portion measured in the radial direction is 1.2 mm or more and 1.4 mm or less, and the wall thickness of the curl portion is thicker than the wall thickness of the male screw portion.

The bottle-type can of the present invention may further include a cap screw-fitted to the male threaded portion, wherein the cap detachably includes a band portion that wraps and engages the bead portion, and the difference between the major axis diameter and the minor axis diameter of the outer diameter of the bead portion may be 0.3 mm or less when the cap is rotated with respect to the mouth/neck portion to detach the band portion and be pulled out from the male threaded portion.

In the bottle-type can of the present invention, the wall thickness of the male screw portion may be 0.28 mm or more and 0.31 mm or less.

Further, the present invention relates to the manufacture of a bottle-type can made of aluminum alloy, in which a shoulder portion whose diameter gradually decreases toward the upper side is continuously formed on the upper end side of a cylindrical body portion, a cylindrical mouth-neck portion is continuously formed in the center of the upper end of the shoulder portion, the tip portion of the mouth-neck portion is formed as a curled portion that bends outward, a male screw portion is formed in a lower portion of the curl portion of the mouth-neck portion, and a bead portion that protrudes outward is formed in a lower portion of the male screw portion. A rough shaped material for a bottle-shaped can used, comprising: a cylindrical body corresponding to the body; a cylindrical shoulder corresponding to the shoulder provided continuously above the body corresponding to the body; a cylindrical neck corresponding to the mouth and neck provided continuously above the shoulder corresponding to being processed to the mouth and neck; It is characterized by being thicker than the wall thickness of the portion corresponding to the mouth and neck portion.

In the blank for a bottle-type can according to the present invention, the wall thickness of the portion corresponding to the neck portion may be thicker than the wall thickness of the portion corresponding to the body portion.

The bottle-shaped can according to the present invention is a metal can having a curl portion with an inner diameter of 30 mm or more. In addition, since the male screw portion and the bead portion are provided, the cap is attached to the mouth and neck portion by roll-on molding and sealed. Therefore, in terms of shape, the external thread portion is likely to be deformed by the radial forming load during roll-on forming (capping). On the other hand, since the height of the curled portion is 1.9 mm or more and 2.0 mm or less, the thickness of the curled portion is 1.2 mm or more and 1.4 mm or less, and the wall thickness of the curled portion is thicker than that of the male threaded portion, the rigidity of the curled portion is sufficiently high. be done. On the other hand, even if the male threaded portion is deformed in the radial direction by forming (thread forming) into a shape that follows the male threaded portion, the deformation is limited by the highly rigid curled portion. That is, by providing the curled portion, which is thicker and more rigid than the male threaded portion, adjacent to the male threaded portion, deformation of the male threaded portion due to capping can be prevented or suppressed. That is, in the present invention, the deformation of the male threaded portion is prevented or suppressed by devising the structure of the curled portion adjacent thereto without changing the structure of the male threaded portion. As a result, when the cap is turned to be opened, the cap can be turned smoothly or without causing a so-called catching, and a bottle-shaped can with no defects in opening performance can be obtained. In addition, since the thickness of the externally threaded portion can be reduced, the weight of the bottle-type can can be reduced, and material consumption can be suppressed, thereby reducing the load on the global environment.

In the present invention, the difference between the long axis diameter (maximum outer diameter) and the short axis diameter (minimum outer diameter), which is the amount of deformation of the bead portion after the cap is removed, is 0.3 mm or less when the cap is opened for the first time.

Furthermore, according to the preformed material according to the present invention, when the portion corresponding to the shoulder portion and the portion corresponding to the mouth/neck portion are formed into a predetermined shoulder portion and mouth/neck portion by, for example, drawing and ironing with respect to the portion corresponding to the body portion, and the tip portion of the mouth/neck portion is formed into a curled portion, the wall thickness of each portion is maintained as it is, or even if it changes, the wall thickness relationship is maintained. Therefore, even if the overall wall thickness is reduced, the wall thickness of the curled portion can be made thicker than the wall thickness of the male threaded portion, and as a result, even if roll-on capping is performed, deformation of the male threaded portion can be prevented or suppressed by the curled portion to obtain a bottle-shaped can with no defects in opening performance.

It is an explanatory view for explaining roll-on capping. FIG. 4 is a schematic diagram for explaining the relative positions of the thread forming rolls and the deformed state of the mouth and neck during roll-on capping. 1 is a front view showing an example of a bottle-type can according to the present invention; FIG. It is a partial cross-sectional view showing an enlarged mouth and neck portion. It is a schematic diagram for demonstrating the deformation amount (distortion amount) of a curl part. 1 is a cross-sectional view showing an example of a coarse shaped material according to the present invention; FIG. (A) is a cross-sectional view showing a state in which a rough shaped material is drawn and ironed to form a shoulder portion and a mouth/neck portion, and (B) is a partial cross-sectional view showing an enlarged view of the mouth/neck portion. (A) is a cross-sectional view showing a part of the rough-shaped material used in Comparative Example 1, and (B) is a cross-sectional view showing a part of the rough-shaped material used in Comparative Example 2;

The invention will now be described with reference to embodiments shown in the drawings. It should be noted that the embodiment described below is merely an example of implementing the present invention, and does not limit the present invention.

FIG. 3 shows an example of a bottle-type can 1 according to the present invention, which is mainly configured as a beverage can. This bottle-type can 1 is a so-called two-piece can made of aluminum alloy, and has a body part 2 and a bottom part 3 integrally formed, for example, by drawing and ironing a thin aluminum plate and gradually drawing the open end side. The body portion 2 is cylindrical, and a shoulder portion 4 is provided continuously on the upper side thereof. The shoulder portion 4 is a portion connected to the mouth/neck portion 5, which will be described later, and has a tapered or domed shape with a gradually decreasing diameter on the upper side.

A mouth/neck portion 5 is formed so as to continue from the central portion of the tip of the shoulder portion 4 . The mouth/neck portion 5 is a portion for attaching a cap C and for a mouth portion 6 that serves as a spout or a spout for drinking, and has a cylindrical shape. FIG. 4 shows a vertical cross section of part of the mouth/neck portion 5. The mouth portion 6, that is, the tip portion of the mouth/neck portion 5 is curled to form a curled portion 7 by bending it outward. A thread groove is formed in a portion connected to the lower side of the curled portion 7 , and this portion serves as a male threaded portion 8 . Further, a band-shaped bead portion 9 projecting outward is formed immediately below the male screw portion 8 . The bead portion 9 is a portion similar to the bead portion 106 shown in FIG. 1, and is a convex portion around which the pilfer proof band (band portion) B is wound.

The bottle-type can 1 shown in FIG. 3 is a metal can with a wide mouth portion 6, and the inside diameter D of the curl portion 7, which is the mouth portion 6, is 30 mm or more. One example is a wide-mouthed bottle type can with a nominal diameter of φ38. Note that the outer diameter of the body portion 2 is 66 mm (φ66). The curled portion 7 has a height H of 1.9 mm or more and 2.0 mm or less, and a thickness W of the curled portion 7 of 1.2 mm or more and 1.4 mm or less. As for the wall thickness, the male threaded portion 8 is thinned in order to reduce the material and the weight of the bottle-type can 1, and the wall thickness t8 is set to 0.28 mm or more and 0.31 mm or less, and the wall thickness t7 of the curl portion 7 is set to be thicker (for example, about 0.33 mm). The wall thickness t8 of the male threaded portion 8 is the thickness measured at a nearly flat portion, for example, the wall thickness at the lower end portion of the male threaded portion 8 (the boundary portion with the bead portion 9). The wall thickness t7 of the curled portion 7 is the wall thickness of the inner peripheral wall of the mouth portion 6. As shown in FIG. Furthermore, the wall thicknesses t7, t8 given here are average values and may deviate locally from these dimension ranges.

Here, the reason why the lower limit of the wall thickness t8 of the male threaded portion 8 is set to 0.28 mm is that if the thickness is thinner than that, the strength of the male threaded portion 8 is insufficient and excessive deformation occurs. Also, the distance from the upper curled portion 7 is short, and it is difficult to set a large wall thickness difference in such a short distance. On the other hand, the reason why the upper limit of the wall thickness t8 of the male threaded portion 8 is set to 0.31 mm is that if it is thicker than 0.31 mm, it is effective in preventing deformation (distortion) of the male threaded portion 8, but the purpose of reducing the material amount by thinning the male threaded portion 8 cannot be achieved.

Also in the bottle-type can 1 according to the present invention, the cap C is attached by the roll-on capping described above with reference to FIG. In this case, as shown in FIG. 2, the male screw portion 8 is deformed or bent, and the curled portion 7 is distorted accordingly. The bottle-type can 1 described above is configured such that the amount of deformation or strain of the curled portion 7 (these are collectively referred to as the amount of deformation) falls within the following range. That is, when the cap C is attached, the curled portion 7 is covered with the cap and the amount of deformation cannot be measured. Further, since the deformation of the curled portion 7 that becomes a problem is the aforementioned oval deformation, the difference between the major axis diameter and the minor axis diameter is taken as the amount of deformation. The major axis diameter d1 is the largest (longest) diameter after being deformed into an elliptical shape, as indicated by the dashed line in FIG. 5, and the minor axis diameter d2 is the smallest (shortest) diameter measured in the direction orthogonal to the major axis. The bottle-shaped can 1 according to the present invention is constructed such that the difference between the major axis diameter d1 and the minor axis diameter d2 is 0.3 mm or less. In other words, the wall thickness t7 of the curled portion 7 is set to an appropriate wall thickness within the above-described dimension range so that the difference between the major axis diameter d1 and the minor axis diameter d2 is 0.3 mm or less and according to the screw forming load during roll-on capping.

The bottle-type can 1 according to the present invention can be manufactured by drawing and ironing an aluminum alloy thin plate as a raw material. FIG. 6 is a cross-sectional view showing the blank 10 during its manufacturing process with the wall thickness exaggerated. The raw material 10 shown here is a so-called intermediate material in which a thin aluminum alloy plate is formed into a cylindrical shape with a bottom and the upper end opening is trimmed. A portion corresponding to the trunk portion 2A to be processed into the trunk portion 2 is formed in the lower portion from the center portion in the vertical direction. A portion connected to the upper side of the trunk portion corresponding portion 2A is the shoulder portion 4A to be processed into the shoulder portion 4. A portion having the same shape as the shoulder portion 4A and continuing to the shoulder portion 4A is the mouth/neck portion 5A to be processed into the mouth/neck portion 5. The portion from the mouth/neck portion 5A to the upper end opening is outside. A portion 7A corresponding to the curled portion is curled to form the curled portion 7 described above. The outer diameters of these portions are substantially the same, but the wall thicknesses are different, and the wall thickness t7A of the portion corresponding to the curl portion 7A is thicker than the wall thickness t5A of the portion corresponding to the mouth and neck portion 5A. The wall thickness t5A of the mouth-and-neck portion 5A and the wall thickness t4A of the lower shoulder portion 4A are the same, and the wall thickness t2A of the lower torso portion 2A is thinner than the wall thickness t4A of the shoulder portion 4A.

The shoulder portion 4A is drawn or ironed to be formed into a tapered or domed shape with a smaller diameter toward the upper side. Further, the portion corresponding to the mouth/neck portion 5A, which is the subsequent portion, is formed into a cylindrical shape, and the portion corresponding to the curl portion 7A is formed into a cylindrical shape having a diameter smaller than that of the portion corresponding to the mouth/neck portion 5A. The shape after such processing is shown in cross section in FIG. In addition, (A) of FIG. 7 is a cross-sectional view of the whole, and (B) is a partial cross-sectional view. Also in these figures, the wall thickness of each portion is exaggerated. As shown in FIG. 7, the wall thickness of each part may change somewhat from the wall thickness of the blank 10 shown in FIG. 6 due to processing, but the mutual difference in wall thickness is maintained. Then, the portion corresponding to the mouth/neck portion 5A is subjected to screw forming processing and bead portion forming processing, and the portion corresponding to the curl portion 7A is subjected to outward curling processing to form the bottle-shaped can 1 shown in FIG. Therefore, the wall thickness of each portion of the blank 10 is set within the range of the wall thickness of each portion of the bottle-shaped can 1 after the above-described drawing or ironing.

The wall thickness of each portion can be adjusted by stepwise increasing the wall thicknesses such that the wall thickness t2A of the portion corresponding to the body portion 2A is the thinnest, the wall thicknesses t4A and t5A of the portion corresponding to the shoulder portion 4A and the mouth/neck portion 5A are made slightly thicker, and the wall thickness t7A of the portion corresponding to the curl portion 7A is maximized. As another method, it is also possible to adjust the clearance in the mold for molding the portion 5A corresponding to the mouth/neck portion and the portion 7A corresponding to the curl portion, and make the wall thickness t7A of the portion 7A corresponding to the curl portion thicker than the wall thickness t5A of the portion 5A corresponding to the mouth/neck portion by utilizing the change in material thickness accompanying the drawing of the portion 7A corresponding to the curl portion.

In the bottle-type can 1 according to the present invention described above, the cap C can be attached to the mouth/neck portion 5 by the roll-on capping described above. In this case, screw forming is performed to screw the cap onto the male thread portion 8 described above. Further, a load that deforms the curled portion 7 is applied to the curled portion 7 by being dragged by the deformation of the male screw portion 8 . The male screw part 8 is made thin to reduce the amount of material or light weight, and its rigidity is reduced accordingly, but the curl part 7 has a wall thickness thicker than that of the male screw part 8 and its rigidity is large, so that the amount of deformation is reduced. In addition, when the load is removed at the end of machining, springback easily restores the normal circular shape. As a result, the curled portion 7 maintains its normal shape or a shape close to it.

Also, although the male threaded portion 8 undergoes deformation (deformation as shown in FIG. 2) during screw forming in the roll-on capping of the forming process, even if the amount of deformation increases somewhat due to the thinning, the male threaded portion 8 itself not only attempts to return to a regular cylindrical shape by springback, but also the deformation and residual deformation of the male threaded portion 8 is eliminated or suppressed by the curl portion 7 which maintains the regular shape or a shape close to it. As a result, in the bottle-type can 1 of the present invention, the aforementioned so-called oval deformation of the male threaded portion 8 is suppressed, so that the cap C rotates smoothly without being caught when unsealed, and the so-called unsealability is improved.

Examples and comparative examples conducted to confirm the effects of the present invention are shown below.

[Example]
A blank was cut out from an aluminum alloy thin plate coil, and the blank was drawn and ironed to form a cylindrical raw material with an outer diameter of 66 mm (φ66). Further, the portion corresponding to the mouth and neck portion was subjected to screw processing, and the opening portion was curled to a curl height of 1.9 to 2.0 mm and a thickness of 1.2 to 1.4 mm to obtain a bottle-shaped can. The produced bottle-shaped cans had two kinds of diameters, namely φ33 (inner diameter of curled portion: 25.05 mm) and φ38 (inner diameter of curled portion: 31.07 mm). The wall thickness of the external thread is 0.31 mm and the wall thickness of the curl is 0.33 mm. Note that FIG. 1 shown above shows a wide-mouthed bottle type can with a nominal diameter of 38 mm.

Bottle-type cans having two types of calibers were filled with water, caps were put on the caps, screws were rolled-on, and the caps were crimped to seal the bottle-type cans. Then, one day later, the cap was opened by hand, and a hand feel test and circular strain measurement of the curl portion (curl portion outer diameter average strain amount) were performed for 10 cans each. Circular distortion was measured by rotating the outer diameter of the curled portion by 20° and optically measuring it with a laser measuring instrument, and measuring the difference (max-min) between the maximum outer diameter and the minimum outer diameter. The results are summarized in Table 1. In Table 1, the term “openability” means that when the portion with the smallest inner diameter of the cap crosses over the portion with the largest outer diameter of the male threaded portion in the rotational direction, the cap and the male threaded portion rub against each other to create a resistance and rubbing noise. On the other hand, the "x" mark indicates that resistance or rubbing noise can be clearly perceived, and the product is evaluated as unacceptable.

[Comparative Example 1]
The shape as a whole was the same as that of the embodiment of the present invention, and the wall thickness of the male threaded portion was the same as that of the curled portion. FIG. 8(A) is a cross-sectional view showing a part of the blank 20 used in Comparative Example 1. The wall thickness t25 of the portion corresponding to the mouth/neck portion 25 processed into the male thread portion and the wall thickness t27 of the portion corresponding to the curl portion 27 processed into the curl portion are each 0.33 mm, and the respective wall thicknesses are maintained substantially as they are after molding into the bottle-shaped can. The bottle-shaped can of Comparative Example 1 has a conventional structure.

The bottle-type can of Comparative Example 1 was filled with water, and the same processing as in the above-described example, such as attaching a cap by roll-on processing and sealing, was performed to test the opening property. The results are shown in Table 1.

[Comparative Example 2]
The overall shape is the same as that of the embodiment of the present invention, and the overall thickness is reduced with the intention of reducing weight and materials, and the wall thickness of the male threaded portion and the wall thickness of the curled portion are set to the same thickness of 0.31 mm. That is, FIG. 8B is a cross-sectional view showing a part of the blank 30 used in Comparative Example 2. The wall thickness t35 of the portion corresponding to the mouth/neck portion 35 processed into the male thread portion and the wall thickness t37 of the portion corresponding to the curl portion 37 processed into the curled portion are each 0.31 mm, and the respective wall thicknesses are maintained substantially as they are after molding into the bottle-shaped can. The bottle-type can of Comparative Example 2 is obtained by thinning the overall thickness of the conventional bottle-type can to reduce the weight.

The bottle-type can of Comparative Example 2 was filled with water, and the same processing as in the above-described example, such as attaching a cap by roll-on processing and sealing, was performed to test the opening property. The results are shown in Table 1.

From the results shown in Table 1, it was found that the distortion of the curled portion after capping tends to increase as the diameter of the curled portion increases. This is thought to have occurred because the positions of the roll-on processing rolls are arranged as shown in FIG. 2 above, and the three rolls rotate the outer periphery of the mouth and neck, so that the larger the diameter, the longer the distance between the thread forming rolls, and as the thread forming rolls revolved, the material was gathered in the direction of revolution, and the larger the diameter, the greater the strain. In addition, in the roll-on process, the curled portion is pressed against the cap by the pressure block as described above, and in this state, the curled portion retains a substantially circular shape. In other words, although the curled portion is dragged and deformed by the male threaded portion, it is considered that the deformation of the male threaded portion is suppressed by the rigidity of the curled portion acting as a resistance.

In the embodiment of the present invention, the wall thickness of the curl portion is thicker than the wall thickness of the male thread portion to maintain rigidity. That is, the curl portion outer diameter average strain amount is less than 0.3 mm. On the other hand, in Comparative Example 2, the curl outer diameter average strain amount is less than 0.3 mm for cans with a caliber (curl portion inner diameter) of φ33 smaller than 30 mm, but the curl outer diameter average strain amount increases to 0.36 mm for a so-called wide-mouthed can with a caliber (curl portion inner diameter) of 31.07 mm. Due to the magnitude of the distortion of the curled portion, in the examples of the present invention, the opening property is good, whereas in the wide-mouthed bottle-shaped can of Comparative Example 2, when the cap is turned in the opening direction, resistance due to rubbing occurs, and the opening property deteriorates. The bottle-type can of Comparative Example 1 had a small amount of average strain on the outer diameter of the curled portion and had good opening properties, but it cannot contribute to the reduction of materials or weight reduction.

As described above, even if the curl portion outer diameter average strain amount is 0.29 mm, the opening property is good, but if it is 0.36 mm, the opening property deteriorates and the product is unacceptable. Therefore, in the present invention, the curl portion strain amount (the difference between the major axis diameter and the minor axis diameter when oval deformation) is 0.3 mm or less when the cap is opened for the first time after roll-on capping.

Although not specifically described in Table 1, when the buckling strength was measured, both Examples and Comparative Examples 1 and 2 showed strength of 1275 N or more, which is the standard, and there was no problem in terms of strength.

As mentioned above, the present invention is not limited to the above-described embodiments, and therefore the above-described specific values for each wall thickness are merely examples, and the present invention may have wall thicknesses different from those values. In any case, the wall thickness may be within a range that satisfies the buckling strength determined by design, and the structure described in the claims may be provided within that range.

1 bottle-shaped can 2 trunk 2A trunk 3 bottom 4 shoulder 4A shoulder 5 mouth/neck 5A mouth/neck 6 mouth 7 curl 7A curl 8 male screw 9 bead 10 raw material 108 pusher block 109 screw forming roll 110 hem tightening roll B pilfer proof band C Cap D Inner diameter H Height W Thickness d1 Major axis diameter d2 Minor axis diameter t2A, t4A, t5A, t7A, t7, t8 Wall thickness

Claims (5)

A bottle-type can made of an aluminum alloy, wherein a shoulder portion whose diameter gradually decreases on the upper end side of a cylindrical body portion is continuously formed, a cylindrical mouth/neck portion is continuously formed at the center of the upper end of the shoulder portion, and the tip portion of the mouth/neck portion is formed as a curled portion that curves outwardly, a male screw portion is formed in a portion below the curl portion of the mouth/neck portion, and a bead portion projecting outward is formed on the lower portion of the male screw portion.
The inner diameter of the curled portion is 30 mm or more,
The height, which is the dimension measured in the axial direction of the curled portion, is 1.9 mm or more and 2.0 mm or less,
The thickness, which is the dimension measured in the radial direction of the curled portion, is 1.2 mm or more and 1.4 mm or less,
A bottle-type can, wherein the wall thickness of the curled portion is thicker than the wall thickness of the male threaded portion. The bottle-type can according to claim 1,
further comprising a cap screw-fitted to the male threaded portion;
The cap is detachably provided with a band portion that wraps and engages the bead portion,
A bottle-shaped can characterized in that the difference between the major axis diameter and the minor axis diameter of the outer diameter of the bead portion is 0.3 mm or less when the cap is rotated with respect to the neck portion to detach the band portion and is pulled out from the male screw portion. In the bottle-type can according to claim 1 or 2,
A bottle-type can, wherein the wall thickness of the male threaded portion is 0.28 mm or more and 0.31 mm or less. A shoulder portion whose diameter is gradually reduced on the upper side is continuously formed on the upper end side of a cylindrical body portion, and a cylindrical mouth/neck portion is continuously formed at the center of the upper end of the shoulder portion. In rough shape materials for
a cylindrical trunk-corresponding portion processed into the trunk;
a cylindrical shoulder-corresponding portion provided continuously on the upper side of the body-corresponding portion and processed into the shoulder portion;
a cylindrical mouth-and-neck portion corresponding to the mouth-and-neck portion continuously provided above the shoulder-like portion;
a cylindrical curled portion corresponding to the curled portion, which is the upper end portion of the portion corresponding to the mouth and neck portion;
A rough shaped material for a bottle-type can, wherein the wall thickness of the portion corresponding to the curl portion is thicker than the wall thickness of the portion corresponding to the mouth/neck portion. In the rough shape material for bottle-type cans according to claim 4,
A rough shaped material for a bottle-type can, wherein the wall thickness of the portion corresponding to the mouth/neck portion is thicker than the wall thickness of the portion corresponding to the body portion.